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• 4121. [Article] Ammonia Volatilization from Nitrogen Fertilizers and Wastewater Reuse in the Columbia Basin

  Ammonia (NH₃) volatilization and loss from nitrogen (N) fertilizer in agriculture negatively impacts crops, farm profitability, human health and surrounding ecosystems where it is deposited. A significant ...

  Citation × Citation Citation Abstract Copy Title: Ammonia Volatilization from Nitrogen Fertilizers and Wastewater Reuse in the Columbia Basin Author: Del Moro, Sarah K. Ammonia (NH₃) volatilization and loss from nitrogen (N) fertilizer in agriculture negatively impacts crops, farm profitability, human health and surrounding ecosystems where it is deposited. A significant source of NH₃ volatilization occurs from surface application of urea on sandy soils with low pH buffering capacity such as those in the semi-arid Columbia Basin region of Oregon and Washington. Ammonia volatilization can be mitigated by using alternative N fertilizers to urea. Effluent from food processing and energy production industries is also used on cropland as an efficient method to conserve water and nutrients. However, NH₃ emissions from effluent application have not been quantified. The objectives of this study were to: (i) quantify NH₃-N loss from urea vs. alternative N fertilizer products in a micrometeorological field study and laboratory incubation experiment, and (ii) quantify NH₃ emissions from effluent applied to crops using an inverse-dispersion micrometeorological method. The fertilizers evaluated in field and laboratory trials included urea, polymer-coated urea, sulfur-coated urea, urea treated with urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)] and ammonium sulfate (AS). Mixed and fused N salts were also evaluated, including a blend of urea and AS and a blend of AS:ammonium nitrate (AN). A modified passive flux method was used to estimate NH₃-N loss from fertilizers in the field experiment for 33 d after application. In the lab incubation trial, NH₃ was collected in acid for 43 d after application. In the field trial, cumulative NH₃-N loss from urea was 47% of N applied. The alternative N fertilizers reduced NH₃-N loss in both the field and laboratory, with the exception of the fused urea:AS blend. The reduction of NH₃-N loss ranged from 19 to 68% vs. urea in the field, and 16 to 98% vs. urea in the laboratory. In the second study, a backward Lagrangian stochastic (bLS) model was used to calculate NH₃ emissions from alfalfa fields receiving effluent water (average 111 mg L⁻¹ total Kjeldahl N content) generated from a potato processor, a dehydrated onion processor, and a cogeneration plant. An ultraviolet-differential optical absorption spectrometer (UV-DOAS) and three-dimensional sonic anemometer were used to monitor NH₃ concentrations, wind speed, and temperature for 43 days downwind of the field. The average NH₃-N emission rate was 1.4 kg ha⁻¹ d⁻¹ when effluent was applied vs. 0.5 kg ha⁻¹ d⁻¹ during irrigation without effluent. The greatest average NH₃-N emission rate of 6.1 kg ha⁻¹ d⁻¹ resulted from alfalfa harvest. These studies provided insight of relative NH₃ loss among a variety of alternative N fertilizers to urea. Additional N mass balance research will be required to validate the accuracy of these NH₃ loss quantifications. Compared to urea, all of the alternative fertilizers significantly reduced NH₃-N loss, with greatest benefit resulting from NO₃⁻ and NH₄⁺ fertilizer forms (> 60% reduction vs. urea). The average NH₃-N emission rate of 1.4 kg ha⁻¹ d⁻¹ observed during effluent application was nearly three times the rate observed from irrigation without effluent. This study confirmed the potential of alternative N fertilizers to reduce NH₃ emission in agriculture in conditions favoring NH₃ volatilization. This study also confirmed the need to consider NH₃ loss when reusing effluent as a nutrient source for crops. Title: Ammonia Volatilization from Nitrogen Fertilizers and Wastewater Reuse in the Columbia Basin Author: Del Moro, Sarah K. Ammonia (NH₃) volatilization and loss from nitrogen (N) fertilizer in agriculture negatively impacts crops, farm profitability, human health and surrounding ecosystems where it is deposited. A significant source of NH₃ volatilization occurs from surface application of urea on sandy soils with low pH buffering capacity such as those in the semi-arid Columbia Basin region of Oregon and Washington. Ammonia volatilization can be mitigated by using alternative N fertilizers to urea. Effluent from food processing and energy production industries is also used on cropland as an efficient method to conserve water and nutrients. However, NH₃ emissions from effluent application have not been quantified. The objectives of this study were to: (i) quantify NH₃-N loss from urea vs. alternative N fertilizer products in a micrometeorological field study and laboratory incubation experiment, and (ii) quantify NH₃ emissions from effluent applied to crops using an inverse-dispersion micrometeorological method. The fertilizers evaluated in field and laboratory trials included urea, polymer-coated urea, sulfur-coated urea, urea treated with urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)] and ammonium sulfate (AS). Mixed and fused N salts were also evaluated, including a blend of urea and AS and a blend of AS:ammonium nitrate (AN). A modified passive flux method was used to estimate NH₃-N loss from fertilizers in the field experiment for 33 d after application. In the lab incubation trial, NH₃ was collected in acid for 43 d after application. In the field trial, cumulative NH₃-N loss from urea was 47% of N applied. The alternative N fertilizers reduced NH₃-N loss in both the field and laboratory, with the exception of the fused urea:AS blend. The reduction of NH₃-N loss ranged from 19 to 68% vs. urea in the field, and 16 to 98% vs. urea in the laboratory. In the second study, a backward Lagrangian stochastic (bLS) model was used to calculate NH₃ emissions from alfalfa fields receiving effluent water (average 111 mg L⁻¹ total Kjeldahl N content) generated from a potato processor, a dehydrated onion processor, and a cogeneration plant. An ultraviolet-differential optical absorption spectrometer (UV-DOAS) and three-dimensional sonic anemometer were used to monitor NH₃ concentrations, wind speed, and temperature for 43 days downwind of the field. The average NH₃-N emission rate was 1.4 kg ha⁻¹ d⁻¹ when effluent was applied vs. 0.5 kg ha⁻¹ d⁻¹ during irrigation without effluent. The greatest average NH₃-N emission rate of 6.1 kg ha⁻¹ d⁻¹ resulted from alfalfa harvest. These studies provided insight of relative NH₃ loss among a variety of alternative N fertilizers to urea. Additional N mass balance research will be required to validate the accuracy of these NH₃ loss quantifications. Compared to urea, all of the alternative fertilizers significantly reduced NH₃-N loss, with greatest benefit resulting from NO₃⁻ and NH₄⁺ fertilizer forms (> 60% reduction vs. urea). The average NH₃-N emission rate of 1.4 kg ha⁻¹ d⁻¹ observed during effluent application was nearly three times the rate observed from irrigation without effluent. This study confirmed the potential of alternative N fertilizers to reduce NH₃ emission in agriculture in conditions favoring NH₃ volatilization. This study also confirmed the need to consider NH₃ loss when reusing effluent as a nutrient source for crops. Close

• 4122. [Article] Emerging infectious disease in lentic environments : the ecology and biogeography of the amphibian chytrid fungus Batrachochytrium dendrobatidis, with perspectives on water quality, limnology, and chemical contaminants

  Biodiversity losses in terrestrial, freshwater, and marine systems are accelerating at a global scale and the most threatened vertebrate taxa are those associated with freshwater habitats. The causes of ...

  Citation × Citation Citation Abstract Copy Title: Emerging infectious disease in lentic environments : the ecology and biogeography of the amphibian chytrid fungus Batrachochytrium dendrobatidis, with perspectives on water quality, limnology, and chemical contaminants Author: Chestnut, Tara Biodiversity losses in terrestrial, freshwater, and marine systems are accelerating at a global scale and the most threatened vertebrate taxa are those associated with freshwater habitats. The causes of biodiversity losses are often complex and include synergistic effects of natural and human-induced stressors, such as habitat loss and fragmentation, urbanization, invasive species, contaminants, global climate change, and emerging infectious diseases. In the last 35 years, the amphibian extinction rate has been estimated to exceed 105 times the baseline expected rate for all species and in the USA, the number of occupied amphibian sites has been reported to be declining by 3.7% per year. Among the many threats to amphibians, the role of disease in population declines has been recognized increasingly over the last two decades. Numerous amphibian diseases have been identified and attributed to mass mortality events. Chytridiomycosis, the emerging infectious disease caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated as a causal agent in many recent global amphibian population declines and extinctions. To understand the pathology and conservation implications of Bd, a greater understanding of its ecology, life history, and distribution in the wild is of paramount importance. Although it has an impact on the persistence of selected amphibian populations around the world, the full scope of the effects of chytridiomycosis on global amphibian population declines are not well understood. Most Bd research efforts have focused on Bd in amphibian hosts per se, with little attention to understand the environmental associations and dynamics of free-living Bd outside of the amphibian host. In particular, information on Bd responses to climatic variation outside of hosts is a research gap. Furthermore, as a microorganism within an aquatic environment, studies are lacking of potential water quality associations, how Bd may interact with other members of their biological communities, and how Bd responses to chemical contaminants found in aquatic environments. My research begins to fill these gaps by studying the basic ecology of free-living Bd in field settings, and investigating factors that may influence its distribution at a landscape scale, occurrence at a regional scale, and detection at a site scale. Herein, I describe spatial and temporal patterns in the detection and density of free-living Bd in aquatic habitats in two different geographic regions of the United States, Alaska (Chapter 2) and Oregon (Chapter 3). The Alaska work examines Bd ecology at the northernmost extent of amphibian occurrence in North America, where climate associations may be particularly relevant and where Bd occurrence may be representative of one of the most novel pathogen-host systems in the world. I also describe (Chapter 2) experimental results of Bd and amphibian response to extreme cold temperatures they may experience in continental settings, at high elevations, and at high latitudes. My Oregon studies (Chapter 3) focus on multivariate associations of free-living Bd occurrences with a suite of aquatic environmental factors, both abiotic and biotic in nature. In Chapter 4, I describe how amphibians and Bd respond to agricultural chemicals (fungicides) that they may be exposed to in field settings. These results are specific to Bd, but might also warrant consideration as fungicidal treatments for a newly described chytrid affecting salamanders; both of these amphibian chytrids have been detected in captive animals and solutions to treat trade animals for the pathogen are gaining relevancy. Finally, in Chapter 5, I reflect upon the journey of conservation biologists and herpetologists for 25 years of amphibian decline research, with global losses becoming widely recognized in 1989. In this context, my research significantly advances understanding of the geographic distribution and ecology of one potential threat factor to amphibian populations on Earth, Batrachochytrium dendrobatidis. The factors that I report to both promote or limit free-living Bd distribution and abundance will further inform pathogen dynamics research. Title: Emerging infectious disease in lentic environments : the ecology and biogeography of the amphibian chytrid fungus Batrachochytrium dendrobatidis, with perspectives on water quality, limnology, and chemical contaminants Author: Chestnut, Tara Biodiversity losses in terrestrial, freshwater, and marine systems are accelerating at a global scale and the most threatened vertebrate taxa are those associated with freshwater habitats. The causes of biodiversity losses are often complex and include synergistic effects of natural and human-induced stressors, such as habitat loss and fragmentation, urbanization, invasive species, contaminants, global climate change, and emerging infectious diseases. In the last 35 years, the amphibian extinction rate has been estimated to exceed 105 times the baseline expected rate for all species and in the USA, the number of occupied amphibian sites has been reported to be declining by 3.7% per year. Among the many threats to amphibians, the role of disease in population declines has been recognized increasingly over the last two decades. Numerous amphibian diseases have been identified and attributed to mass mortality events. Chytridiomycosis, the emerging infectious disease caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated as a causal agent in many recent global amphibian population declines and extinctions. To understand the pathology and conservation implications of Bd, a greater understanding of its ecology, life history, and distribution in the wild is of paramount importance. Although it has an impact on the persistence of selected amphibian populations around the world, the full scope of the effects of chytridiomycosis on global amphibian population declines are not well understood. Most Bd research efforts have focused on Bd in amphibian hosts per se, with little attention to understand the environmental associations and dynamics of free-living Bd outside of the amphibian host. In particular, information on Bd responses to climatic variation outside of hosts is a research gap. Furthermore, as a microorganism within an aquatic environment, studies are lacking of potential water quality associations, how Bd may interact with other members of their biological communities, and how Bd responses to chemical contaminants found in aquatic environments. My research begins to fill these gaps by studying the basic ecology of free-living Bd in field settings, and investigating factors that may influence its distribution at a landscape scale, occurrence at a regional scale, and detection at a site scale. Herein, I describe spatial and temporal patterns in the detection and density of free-living Bd in aquatic habitats in two different geographic regions of the United States, Alaska (Chapter 2) and Oregon (Chapter 3). The Alaska work examines Bd ecology at the northernmost extent of amphibian occurrence in North America, where climate associations may be particularly relevant and where Bd occurrence may be representative of one of the most novel pathogen-host systems in the world. I also describe (Chapter 2) experimental results of Bd and amphibian response to extreme cold temperatures they may experience in continental settings, at high elevations, and at high latitudes. My Oregon studies (Chapter 3) focus on multivariate associations of free-living Bd occurrences with a suite of aquatic environmental factors, both abiotic and biotic in nature. In Chapter 4, I describe how amphibians and Bd respond to agricultural chemicals (fungicides) that they may be exposed to in field settings. These results are specific to Bd, but might also warrant consideration as fungicidal treatments for a newly described chytrid affecting salamanders; both of these amphibian chytrids have been detected in captive animals and solutions to treat trade animals for the pathogen are gaining relevancy. Finally, in Chapter 5, I reflect upon the journey of conservation biologists and herpetologists for 25 years of amphibian decline research, with global losses becoming widely recognized in 1989. In this context, my research significantly advances understanding of the geographic distribution and ecology of one potential threat factor to amphibian populations on Earth, Batrachochytrium dendrobatidis. The factors that I report to both promote or limit free-living Bd distribution and abundance will further inform pathogen dynamics research. Close

• 4123. [Article] Improving Projections of Tidal Marsh Persistence under Climate Change with Remote Sensing and Site-Specific Data

  Tidal marshes are dynamic ecosystems that are threatened by climate change and sea-level rise. To characterize baseline condition and historic climate sensitivities, and improve projections into the future, ...

  Citation × Citation Citation Abstract Copy Title: Improving Projections of Tidal Marsh Persistence under Climate Change with Remote Sensing and Site-Specific Data Author: Buffington, Kevin John Tidal marshes are dynamic ecosystems that are threatened by climate change and sea-level rise. To characterize baseline condition and historic climate sensitivities, and improve projections into the future, new methods are required that integrate data from the field and remote sensing platforms. Marsh elevation response models can be calibrated with site-specific data to determine the vulnerability of a marsh to sea-level rise and help guide management decisions. Elevation models are sensitive to initial elevation, the rate of accretion, and aboveground biomass. The overarching goal of this dissertation was to develop techniques to improve these important model inputs and evaluate the range of spatial and temporal variation. Light detection and ranging (lidar) is an invaluable tool for collecting elevation data, however dense vegetation prevents the accurate measurement of the tidal marsh surface. In Chapter 2, I describe the development of a technique to calibrate lidar digital elevation models with survey elevation data using readily available multispectral aerial imagery from the National Agricultural Inventory Program (NAIP). Using survey elevation data across 17 Pacific Coast tidal marshes, I demonstrated the utility of the Lidar Elevation Adjustment with NDVI (LEAN) technique to account for the positive bias in lidar due to vegetation. LEAN reduced error from an average of 23.1 cm to 7.2 cm root mean squared error and removed the positive bias caused by vegetation. This increase in accuracy will facilitate more accurate assessments of current and future vulnerability to sea-level rise. The phenology of aboveground biomass in tidal marsh plants in relation to climate variation has not been explored in the Pacific Northwest (PNW). In Chapter 3 I explain how I leveraged the Landsat archive and cloud computing capabilities to assess how Tasseled Cap Greenness (TCG, a proxy for aboveground biomass) in three PNW tidal marshes has responded to recent variation in climate to characterize sensitivity to climate change. Through analysis of over 3700 Landsat images obtained from 1984-2015, I found increased annual precipitation resulted in a higher peak TCG, while warmer May temperatures resulted in an earlier day of peak TCG. These results also demonstrate how time-series analysis of remote sensing data can be used to examine the sensitivity of tidal marsh plants to climate variability and directional change. The range of variation in tidal marsh accretion rates has not been characterized across the PNW. For Chapter 4, I collected and analyzed twenty-two soil cores from eight estuaries to estimate historic accretion rates with radioisotope dating techniques and evaluated the amount and source of variation across estuaries. I found that tidal marshes across the PNW had accretion rates greater than the current rate of sea-level rise, ranging from 2.3 – 7.3 mm yr⁻¹. Using a watershed-scale analysis, I found that long-term average annual fluvial discharge was the top predictor of tidal marsh accretion rates. Additionally, I found that calibrating the Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) with accretion rate data from nearby estuaries can result in uncertainties of up to 41% (50 cm) after 100 years. Finally, in Chapter 5, I demonstrate that a range of 62 cm of error is possible in WARMER models after a 100 year simulation when both uncorrected lidar and non-local accretion rates are used, fundamentally changing the interpretation of the results. Altogether, this dissertation illustrates the importance of collecting site-specific wetland vegetation and elevation data and demonstrates how lidar and multispectral remote sensing data can be leveraged to improve our understanding of how climate variability and change impacts coastal ecosystems. Title: Improving Projections of Tidal Marsh Persistence under Climate Change with Remote Sensing and Site-Specific Data Author: Buffington, Kevin John Tidal marshes are dynamic ecosystems that are threatened by climate change and sea-level rise. To characterize baseline condition and historic climate sensitivities, and improve projections into the future, new methods are required that integrate data from the field and remote sensing platforms. Marsh elevation response models can be calibrated with site-specific data to determine the vulnerability of a marsh to sea-level rise and help guide management decisions. Elevation models are sensitive to initial elevation, the rate of accretion, and aboveground biomass. The overarching goal of this dissertation was to develop techniques to improve these important model inputs and evaluate the range of spatial and temporal variation. Light detection and ranging (lidar) is an invaluable tool for collecting elevation data, however dense vegetation prevents the accurate measurement of the tidal marsh surface. In Chapter 2, I describe the development of a technique to calibrate lidar digital elevation models with survey elevation data using readily available multispectral aerial imagery from the National Agricultural Inventory Program (NAIP). Using survey elevation data across 17 Pacific Coast tidal marshes, I demonstrated the utility of the Lidar Elevation Adjustment with NDVI (LEAN) technique to account for the positive bias in lidar due to vegetation. LEAN reduced error from an average of 23.1 cm to 7.2 cm root mean squared error and removed the positive bias caused by vegetation. This increase in accuracy will facilitate more accurate assessments of current and future vulnerability to sea-level rise. The phenology of aboveground biomass in tidal marsh plants in relation to climate variation has not been explored in the Pacific Northwest (PNW). In Chapter 3 I explain how I leveraged the Landsat archive and cloud computing capabilities to assess how Tasseled Cap Greenness (TCG, a proxy for aboveground biomass) in three PNW tidal marshes has responded to recent variation in climate to characterize sensitivity to climate change. Through analysis of over 3700 Landsat images obtained from 1984-2015, I found increased annual precipitation resulted in a higher peak TCG, while warmer May temperatures resulted in an earlier day of peak TCG. These results also demonstrate how time-series analysis of remote sensing data can be used to examine the sensitivity of tidal marsh plants to climate variability and directional change. The range of variation in tidal marsh accretion rates has not been characterized across the PNW. For Chapter 4, I collected and analyzed twenty-two soil cores from eight estuaries to estimate historic accretion rates with radioisotope dating techniques and evaluated the amount and source of variation across estuaries. I found that tidal marshes across the PNW had accretion rates greater than the current rate of sea-level rise, ranging from 2.3 – 7.3 mm yr⁻¹. Using a watershed-scale analysis, I found that long-term average annual fluvial discharge was the top predictor of tidal marsh accretion rates. Additionally, I found that calibrating the Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) with accretion rate data from nearby estuaries can result in uncertainties of up to 41% (50 cm) after 100 years. Finally, in Chapter 5, I demonstrate that a range of 62 cm of error is possible in WARMER models after a 100 year simulation when both uncorrected lidar and non-local accretion rates are used, fundamentally changing the interpretation of the results. Altogether, this dissertation illustrates the importance of collecting site-specific wetland vegetation and elevation data and demonstrates how lidar and multispectral remote sensing data can be leveraged to improve our understanding of how climate variability and change impacts coastal ecosystems. Close

• 4124. [Article] A comparison of modeling schemes for mapping daily evapotranspiration at high resolution using remote sensing

  Evapotranspiration (ET) is an important component of the hydrologic cycle that transfers large quantities of water vapor away from Earth's surface into the atmosphere. In addition to having agricultural ...

  Citation × Citation Citation Abstract Copy Title: A comparison of modeling schemes for mapping daily evapotranspiration at high resolution using remote sensing Author: Ring, Theresa Evapotranspiration (ET) is an important component of the hydrologic cycle that transfers large quantities of water vapor away from Earth's surface into the atmosphere. In addition to having agricultural water management applications, including monitoring water rights compliance and irrigation scheduling, estimating ET is also important to quantify water used by other landscapes for soil-vegetation-atmosphere-transfer (SVAT) modeling schemes. This can only be done by estimating ET at large scales and this is most efficiently achieved by remote sensing. Daily ET was retrieved from two remote sensing modeling schemes: a) Reconstructed METRIC: Mapping EvapoTranspiration at high Resolution with Internalized Calibration (R-METRIC) that uses thermal band data from the Landsat 8 satellite; and b) Fusion: ALEXI/DisALEXI (Atmosphere-Land EXchange Inverse/Disaggregated ALEXI) and STARFM (Spatial and Temporal Adaptive Reflectance Fusion Model) that combines GOES (Geostationary Operational Environmental Satellite), MODIS (Moderate-resolution Imaging Spectroradiometer) and Landsat 8. High resolution, daily ET was mapped over two predominately wooded or forested, water stressed study locations at Tonzi Ranch in California and Metolius Forest in Oregon for the summer months of 2013. Both sites have established networks of eddy covariance instruments that acquire high temporal resolution moisture flux data. Instantaneous surface energy fluxes estimated by R-METRIC at the Tonzi study site showed reasonable agreement with in situ measurements over the flux tower footprint with relative errors (RE) less than 15% for all fluxes except latent heat (λET) which showed RE = 31%. Validation at the Vaira and Metolius towers showed similar results with the exception of significantly overestimating λET (RE = 297%) at Vaira and soil heat flux at Metolius (RE = 169%). DisALEXI showed good agreement for solar and net radiation (RE < 13%) at all sites. Significant overestimations of λET (RE up to 540%) and underestimations of sensible heat (RE up to 65%) were produced at each site. Additionally, soil heat flux at Metolius showed errors up to 167%. While daily ET at Tonzi modeled with R-METRIC agreed well with observed measurements, modeled values of daily ET were significantly overestimated at Vaira (RE = 395%). DisALEXI showed severe overestimations of daily ET at both Tonzi and Vaira (RE = 428 and 596%, respectively). It should be noted that the observed daily ET at these sites is very low compared to the sensible heat flux which leads to the unexpectedly high error. At Metolius, the two models produced comparable results though they both overestimated the observed daily ET. Because daily ET was overestimated, the seasonal cumulative ET was also overestimated at all sites by both models with the exception of R-METRIC over Tonzi. Surface and evaporative fluxes retrieved from the two models were also inter-compared over the different land cover types in the scenes. As both schemes were specifically developed for use over agricultural lands, they agree reasonably well with measurements when used over that land cover type. When applied over other land covers, specifically forests, grassland and shrubs, the daily ET showed greater discrepancies. The results of this study suggest that the current version of the Fusion scheme estimates much higher ET than actually occurs at all three tower locations at both instantaneous and daily scales. This likely results from the ALEXI processing step in which the air temperature for input into DisALEXI is found. Though relatively easy for the user to implement this model, until that step is debugged, it remains unclear how accurate it may be over non-agricultural environments. R-METRIC shows good agreement at the instantaneous scale but more discrepancy at the daily scale. Unlike the Fusion scheme, R-METRIC requires user discretion in order to calibrate it to the study site and is therefore subject to user bias. Though both models have proven their utility over agricultural fields, the water stressed conditions at both sites present a challenging yet important environment that needs improved accuracy in both models. Title: A comparison of modeling schemes for mapping daily evapotranspiration at high resolution using remote sensing Author: Ring, Theresa Evapotranspiration (ET) is an important component of the hydrologic cycle that transfers large quantities of water vapor away from Earth's surface into the atmosphere. In addition to having agricultural water management applications, including monitoring water rights compliance and irrigation scheduling, estimating ET is also important to quantify water used by other landscapes for soil-vegetation-atmosphere-transfer (SVAT) modeling schemes. This can only be done by estimating ET at large scales and this is most efficiently achieved by remote sensing. Daily ET was retrieved from two remote sensing modeling schemes: a) Reconstructed METRIC: Mapping EvapoTranspiration at high Resolution with Internalized Calibration (R-METRIC) that uses thermal band data from the Landsat 8 satellite; and b) Fusion: ALEXI/DisALEXI (Atmosphere-Land EXchange Inverse/Disaggregated ALEXI) and STARFM (Spatial and Temporal Adaptive Reflectance Fusion Model) that combines GOES (Geostationary Operational Environmental Satellite), MODIS (Moderate-resolution Imaging Spectroradiometer) and Landsat 8. High resolution, daily ET was mapped over two predominately wooded or forested, water stressed study locations at Tonzi Ranch in California and Metolius Forest in Oregon for the summer months of 2013. Both sites have established networks of eddy covariance instruments that acquire high temporal resolution moisture flux data. Instantaneous surface energy fluxes estimated by R-METRIC at the Tonzi study site showed reasonable agreement with in situ measurements over the flux tower footprint with relative errors (RE) less than 15% for all fluxes except latent heat (λET) which showed RE = 31%. Validation at the Vaira and Metolius towers showed similar results with the exception of significantly overestimating λET (RE = 297%) at Vaira and soil heat flux at Metolius (RE = 169%). DisALEXI showed good agreement for solar and net radiation (RE < 13%) at all sites. Significant overestimations of λET (RE up to 540%) and underestimations of sensible heat (RE up to 65%) were produced at each site. Additionally, soil heat flux at Metolius showed errors up to 167%. While daily ET at Tonzi modeled with R-METRIC agreed well with observed measurements, modeled values of daily ET were significantly overestimated at Vaira (RE = 395%). DisALEXI showed severe overestimations of daily ET at both Tonzi and Vaira (RE = 428 and 596%, respectively). It should be noted that the observed daily ET at these sites is very low compared to the sensible heat flux which leads to the unexpectedly high error. At Metolius, the two models produced comparable results though they both overestimated the observed daily ET. Because daily ET was overestimated, the seasonal cumulative ET was also overestimated at all sites by both models with the exception of R-METRIC over Tonzi. Surface and evaporative fluxes retrieved from the two models were also inter-compared over the different land cover types in the scenes. As both schemes were specifically developed for use over agricultural lands, they agree reasonably well with measurements when used over that land cover type. When applied over other land covers, specifically forests, grassland and shrubs, the daily ET showed greater discrepancies. The results of this study suggest that the current version of the Fusion scheme estimates much higher ET than actually occurs at all three tower locations at both instantaneous and daily scales. This likely results from the ALEXI processing step in which the air temperature for input into DisALEXI is found. Though relatively easy for the user to implement this model, until that step is debugged, it remains unclear how accurate it may be over non-agricultural environments. R-METRIC shows good agreement at the instantaneous scale but more discrepancy at the daily scale. Unlike the Fusion scheme, R-METRIC requires user discretion in order to calibrate it to the study site and is therefore subject to user bias. Though both models have proven their utility over agricultural fields, the water stressed conditions at both sites present a challenging yet important environment that needs improved accuracy in both models. Close

• 4125. [Article] Seasonal life history of Oncorhynchus mykiss in the South Fork John Day River Basin, Oregon

  Understanding seasonal changes in growth, survival, and movement rates is crucial to salmonid management. These life history characteristics provide a context for evaluation of management actions. We evaluated ...

  Citation × Citation Citation Abstract Copy Title: Seasonal life history of Oncorhynchus mykiss in the South Fork John Day River Basin, Oregon Author: Tattam, Ian A. Understanding seasonal changes in growth, survival, and movement rates is crucial to salmonid management. These life history characteristics provide a context for evaluation of management actions. We evaluated the life history of individually marked Oncorhynchus mykiss gairdneri in the South Fork John Day River basin in Northeastern Oregon. This thesis focuses on Murderers and Black Canyon creeks, two tributaries to the South Fork John Day. These are semi-arid, mid elevation basins with naturally reproducing populations of summer steelhead and redband trout (both O. mykiss). Summer steelhead populations in this basin have declined from historic abundances, and are protected under the Endangered Species Act. In Chapter 2, we evaluate life history variation in Murderers Creek during four consecutive seasons. Growth rate varied significantly with season (F[subscript 3,88] = 62.56, P < 0.0001), with most growth occurring during spring. Location and season interacted F[subscript 6,88] = 4.45, P < 0.001) to influence individual growth rates. As a result, regions of high growth potential shifted up and down-stream seasonally. However, we found low rates of O. mykiss movement (<3%) in Murderers Creek during summer, suggesting that individuals did not track resource availability at a large scale. Apparent survival rate varied among reaches, but was consistently higher in the upstream most reach compared to the two lowermost reaches. Survival rates were similar between summer and fall, indicating that declining fall temperatures did not increase mortality. A shift in population distribution occured during fall (September through December), as some O. mykiss emigrated from tributaries into the mainstem South Fork John Day River. In Chapter 3, we investigate differences in fall life history between and within tributaries. A significantly greater proportion of O. mykiss emigrated from Murderers Creek compared to Black Canyon Creek during two consecutive years (P < 0.001 for both years). There were no significant differences in proportion of emigrants between years within either stream (P > 0.10 for both streams). In Murderers Creek, odds of emigration were related to stream reach of summer residence. Odds of fall emigration were also significantly and positively related to body length in fall and growth rate during summer. This suggests that competitive dominants volitionally emigrated from Murderers Creek during fall. After emigration, O. mykiss dispersed primarily further downstream into the Mainstem John Day River. Radio-telemetry indicated that the majority of fall emigrants occupied a < 6 km section of the Mainstem John Day River. Fall emigrants had growth rates during their winter niche shift that were significantly (P < 0.001) higher than those of individuals remaining in tributaries. This study underscores the need to monitor during all seasons to accurately characterize habitat quality. Life history patterns are an important population response to environmental change. This thesis provides an ecological context for monitoring recovery of O. mykiss populations in the South Fork John Day River basin. Title: Seasonal life history of Oncorhynchus mykiss in the South Fork John Day River Basin, Oregon Author: Tattam, Ian A. Understanding seasonal changes in growth, survival, and movement rates is crucial to salmonid management. These life history characteristics provide a context for evaluation of management actions. We evaluated the life history of individually marked Oncorhynchus mykiss gairdneri in the South Fork John Day River basin in Northeastern Oregon. This thesis focuses on Murderers and Black Canyon creeks, two tributaries to the South Fork John Day. These are semi-arid, mid elevation basins with naturally reproducing populations of summer steelhead and redband trout (both O. mykiss). Summer steelhead populations in this basin have declined from historic abundances, and are protected under the Endangered Species Act. In Chapter 2, we evaluate life history variation in Murderers Creek during four consecutive seasons. Growth rate varied significantly with season (F[subscript 3,88] = 62.56, P < 0.0001), with most growth occurring during spring. Location and season interacted F[subscript 6,88] = 4.45, P < 0.001) to influence individual growth rates. As a result, regions of high growth potential shifted up and down-stream seasonally. However, we found low rates of O. mykiss movement (<3%) in Murderers Creek during summer, suggesting that individuals did not track resource availability at a large scale. Apparent survival rate varied among reaches, but was consistently higher in the upstream most reach compared to the two lowermost reaches. Survival rates were similar between summer and fall, indicating that declining fall temperatures did not increase mortality. A shift in population distribution occured during fall (September through December), as some O. mykiss emigrated from tributaries into the mainstem South Fork John Day River. In Chapter 3, we investigate differences in fall life history between and within tributaries. A significantly greater proportion of O. mykiss emigrated from Murderers Creek compared to Black Canyon Creek during two consecutive years (P < 0.001 for both years). There were no significant differences in proportion of emigrants between years within either stream (P > 0.10 for both streams). In Murderers Creek, odds of emigration were related to stream reach of summer residence. Odds of fall emigration were also significantly and positively related to body length in fall and growth rate during summer. This suggests that competitive dominants volitionally emigrated from Murderers Creek during fall. After emigration, O. mykiss dispersed primarily further downstream into the Mainstem John Day River. Radio-telemetry indicated that the majority of fall emigrants occupied a < 6 km section of the Mainstem John Day River. Fall emigrants had growth rates during their winter niche shift that were significantly (P < 0.001) higher than those of individuals remaining in tributaries. This study underscores the need to monitor during all seasons to accurately characterize habitat quality. Life history patterns are an important population response to environmental change. This thesis provides an ecological context for monitoring recovery of O. mykiss populations in the South Fork John Day River basin. Close

• 4126. [Article] The Application of Brine Injection Technology to Improve Quality of Pacific whiting (Merluccius productus) Fillets

  Existing research reports the importance of brine injection technology in enhancing the quality of muscle products such as poultry, beef, and pork. In fish, the utilization of brine injection technology ...

  Citation × Citation Citation Abstract Copy Title: The Application of Brine Injection Technology to Improve Quality of Pacific whiting (Merluccius productus) Fillets Author: Harikedua, Silvana Dinaintang Existing research reports the importance of brine injection technology in enhancing the quality of muscle products such as poultry, beef, and pork. In fish, the utilization of brine injection technology is well-known for delivering marinade ingredients for salted or smoked fish production. Until now, there has been limited published scientific evidence on the incorporation of brine ingredients containing protease inhibitors to improve the quality of fresh or frozen fish fillets. Thus, the studies presented in this thesis focused on improving the quality of Pacific whiting (Merluccius productus) fillets through brine injection technology. Pacific whiting fillets are not considered desirable in the U.S. market because their meat is easily softened during slow cooking. The first study explored whether multi-needle injection technology is applicable to the improvement of Pacific whiting raw fillet quality. Color, texture, rancidity, moisture and protein were determined to understand how brine treatments affected appearance, oxidative stability and composition of the fillets. The impact of brine ingredients on myofibril protein was evaluated by gel electrophoresis. All brines were formulated with a base solution (3% sodium tripolyphosphate and 3% salt). Treatments consisted of base brine (B), base brine + 3% egg white (B[subscript EW]), and base brine + 0.1% xanthan gum+ 3% dried potato extract (B[subscript PE]). Ten fillets were injected per treatment and a 10% brine uptake was targeted for all fillets. Actual brine incorporation was 12.35 ± 2.28%. The lightness (L*) value of raw fillets indicated that B[subscript EW] and B[subscript PE] were darker than C and B (P < 0.05). Breaking strength demonstrated higher variability in non-injected samples than in injected samples. Enzyme assays showed no differences between all treatments when it was tested using buffer at pH 5.5 (P = 0.06). SDS-PAGE analysis showed minor changes in myofibril proteins between injected fillets and non-injected fillets. The second study aimed to evaluate the brine effectiveness in inhibiting protease activity in the fillet through heating. Control samples included non-injected (NI) fillets and fillets injected with water (W) only. For all other treatments, brines contained 3% (w/w) salt and sodium tripolyphosphate as a base brine (B). Additional, brine treatments with egg white were a combination of the base brine (B) with either 1, 2 or 3% egg white (B[subscript 1EW], B[subscript 2EW], B[subscript 3EW]). For potato extract, 0.1% xanthan gum was added to the base brine to aid in its suspension (BXG). Potato extract was added to B[subscript XG] at similar levels as egg white (B[subscript 1PE], B[subscript 2PE], B[subscript 3PE]). Previously frozen butterfly fillets were tempered to 2.0 ± 1.0 °C, injected with a selected treatment, vacuum packaged and immediately cooked in either one of two different heating conditions. Vacuum packed fillets were either submerged in water at 90 °C for 20 min to achieve a final internal temperature 62.8 °C (145 °F) or submerged in a 60 °C water bath for 30 min and then immediately transferred to a 90 °C water bath for 20 minutes. The pH, moisture, crude protein, total extractable protein, total non-extractable protein, texture profile analysis, and SDS-PAGE electrophoretic pattern in cooked fillets were determined. For TPA measurements, an uninjected cod sample was used as a reference sample. Compositional analysis determined the cooked NI fillet was less moist than all injected samples (P < 0.05), suggesting TPA attributes would be higher than injected samples, which was confirmed. Protein patterns from SDS-PAGE electrophoresis indicated that the myosin bands were slightly diminished when fillets were heated at 60 °C prior to cooking at 90 °C for all treatments, except in fillets containing egg white or potato extract ingredients, suggesting these treatments provided some protection to myofibrillar structure. Fillets cooked using the challenge heat treatment were significantly (P < 0.05) softer than those cooked using the sous vide for all TPA attributes. Additionally, future research considerations that would benefit the applicability of the injection process to fillet quality improvement should include determining the appropriate fish size to target for the injection process, the shelf life of injected fillets during frozen or refrigerated storage, and consumer acceptance of the injected fillets. Title: The Application of Brine Injection Technology to Improve Quality of Pacific whiting (Merluccius productus) Fillets Author: Harikedua, Silvana Dinaintang Existing research reports the importance of brine injection technology in enhancing the quality of muscle products such as poultry, beef, and pork. In fish, the utilization of brine injection technology is well-known for delivering marinade ingredients for salted or smoked fish production. Until now, there has been limited published scientific evidence on the incorporation of brine ingredients containing protease inhibitors to improve the quality of fresh or frozen fish fillets. Thus, the studies presented in this thesis focused on improving the quality of Pacific whiting (Merluccius productus) fillets through brine injection technology. Pacific whiting fillets are not considered desirable in the U.S. market because their meat is easily softened during slow cooking. The first study explored whether multi-needle injection technology is applicable to the improvement of Pacific whiting raw fillet quality. Color, texture, rancidity, moisture and protein were determined to understand how brine treatments affected appearance, oxidative stability and composition of the fillets. The impact of brine ingredients on myofibril protein was evaluated by gel electrophoresis. All brines were formulated with a base solution (3% sodium tripolyphosphate and 3% salt). Treatments consisted of base brine (B), base brine + 3% egg white (B[subscript EW]), and base brine + 0.1% xanthan gum+ 3% dried potato extract (B[subscript PE]). Ten fillets were injected per treatment and a 10% brine uptake was targeted for all fillets. Actual brine incorporation was 12.35 ± 2.28%. The lightness (L*) value of raw fillets indicated that B[subscript EW] and B[subscript PE] were darker than C and B (P < 0.05). Breaking strength demonstrated higher variability in non-injected samples than in injected samples. Enzyme assays showed no differences between all treatments when it was tested using buffer at pH 5.5 (P = 0.06). SDS-PAGE analysis showed minor changes in myofibril proteins between injected fillets and non-injected fillets. The second study aimed to evaluate the brine effectiveness in inhibiting protease activity in the fillet through heating. Control samples included non-injected (NI) fillets and fillets injected with water (W) only. For all other treatments, brines contained 3% (w/w) salt and sodium tripolyphosphate as a base brine (B). Additional, brine treatments with egg white were a combination of the base brine (B) with either 1, 2 or 3% egg white (B[subscript 1EW], B[subscript 2EW], B[subscript 3EW]). For potato extract, 0.1% xanthan gum was added to the base brine to aid in its suspension (BXG). Potato extract was added to B[subscript XG] at similar levels as egg white (B[subscript 1PE], B[subscript 2PE], B[subscript 3PE]). Previously frozen butterfly fillets were tempered to 2.0 ± 1.0 °C, injected with a selected treatment, vacuum packaged and immediately cooked in either one of two different heating conditions. Vacuum packed fillets were either submerged in water at 90 °C for 20 min to achieve a final internal temperature 62.8 °C (145 °F) or submerged in a 60 °C water bath for 30 min and then immediately transferred to a 90 °C water bath for 20 minutes. The pH, moisture, crude protein, total extractable protein, total non-extractable protein, texture profile analysis, and SDS-PAGE electrophoretic pattern in cooked fillets were determined. For TPA measurements, an uninjected cod sample was used as a reference sample. Compositional analysis determined the cooked NI fillet was less moist than all injected samples (P < 0.05), suggesting TPA attributes would be higher than injected samples, which was confirmed. Protein patterns from SDS-PAGE electrophoresis indicated that the myosin bands were slightly diminished when fillets were heated at 60 °C prior to cooking at 90 °C for all treatments, except in fillets containing egg white or potato extract ingredients, suggesting these treatments provided some protection to myofibrillar structure. Fillets cooked using the challenge heat treatment were significantly (P < 0.05) softer than those cooked using the sous vide for all TPA attributes. Additionally, future research considerations that would benefit the applicability of the injection process to fillet quality improvement should include determining the appropriate fish size to target for the injection process, the shelf life of injected fillets during frozen or refrigerated storage, and consumer acceptance of the injected fillets. Close

• 4127. [Article] The Global Consumption Speeds of Premixed Large-Hydrocarbon Fuel/Air Turbulent Bunsen Flames

  Large-hydrocarbon fuels are used for ground and air transportation because of their high energy-density and will be for the foreseeable future. However, combustion of large-hydrocarbon fuels in a turbulent ...

  Citation × Citation Citation Abstract Copy Title: The Global Consumption Speeds of Premixed Large-Hydrocarbon Fuel/Air Turbulent Bunsen Flames Author: Fillo, Aaron Jesse Large-hydrocarbon fuels are used for ground and air transportation because of their high energy-density and will be for the foreseeable future. However, combustion of large-hydrocarbon fuels in a turbulent environment is poorly understood and difficult to predict. The turbulent flame speed, which is the velocity at which a flame front propagates through a turbulent fuel and air mixture, is a key property in turbulent combustion. The turbulent flame speed can be used as a model input parameter for tur- bulent combustion simulations. However, turbulent flame speeds for large-hydrocarbon fuels are largely unknown. These values are needed to improve combustion models and enhance understanding of the physics and chemistry that control turbulent combustion of large-hydrocarbon fuels. The objective of this study is to measure the turbulent flame speed of large-hydrocarbon fuels and to identify key physics in the turbulent combustion of these fuels. This is motivated by the use of the turbulent flame speeds in modeling combustion in practical devices and the significant use of large-hydrocarbons in these devices. This research has broad implications for society and industry; both the Federal Aviation Administration and gas turbine engine companies have called for research on the turbulent flame speeds of large-hydrocarbon fuels. The turbulent flame speed in this work is defined as the global consumption speed, and is measured for three fuels on a turbulent Bunsen burner. The Reynolds number, turbulence intensity, preheat temperature, and equivalent ratio can be independently controlled using the burner. A conventional Jet-A fuel, known as A2, is used as a reference because of its common use in commercial and military aviation. A2 is compared to bi-modal and quadra-modal blends referred to as C1 and C5, respectively. These fuels are selected as they have similar heat releases and laminar flame speeds. Time-averaged line of site images of OH*, CH*, and CO₂* chemiluminescence are used to determine an the average flame front area. This flame area is used to determine the global consumption speed. The global consumption speed is measured for Reynolds number and equivalence ratio ranging between 5.000-10.000 and 0.7-1, respectively. Turbulence intensities are varied between 10% and 20% of the bulk flow velocity. The global consumption speed increases with turbulence intensity and Reynolds number for all fuels. Global consumption speeds for A2 and C5 match within 5% at all conditions. Conversely, the global consumption speed of C1 is up to 22% lower than A2 or C5. These results indicate the global consumption speed is sensitive to turbulent velocity fluctuations, bulk flow velocity, and fuel chemistry. These results together suggest the global consumption speed is additionally sensitive to flame stretch. Dimensional analysis is used to isolate and identify sensitivities of the global consumption speed to turbulent velocity fluctuations, bulk flow velocity, global stretch rate, and fuel chemistry. A clear sensitivity to fuel chemistry is observed and is affected by aromatic and alkane content. A2 and C5 have higher global consumptions speeds and increased stability; these fuels have shorter average hydrocarbon chain lengths and higher aro- matic content than C1. In addition, the global consumption speed is highly sensitive to turbulence intensity of the flow; the turbulent flame speed increases an average of 30% for all fuels between the minimum and maximum turbulence intensity cases. Results are attributed to a strong sensitivity of the global consumption speed to flame stretch and a strong coupling of turbulence and fuel chemistry effects. These conclusions agree with the available literature and provide a foundational understanding of the sensitivities of the global consumption speed for large-hydrocarbon fuels. Title: The Global Consumption Speeds of Premixed Large-Hydrocarbon Fuel/Air Turbulent Bunsen Flames Author: Fillo, Aaron Jesse Large-hydrocarbon fuels are used for ground and air transportation because of their high energy-density and will be for the foreseeable future. However, combustion of large-hydrocarbon fuels in a turbulent environment is poorly understood and difficult to predict. The turbulent flame speed, which is the velocity at which a flame front propagates through a turbulent fuel and air mixture, is a key property in turbulent combustion. The turbulent flame speed can be used as a model input parameter for tur- bulent combustion simulations. However, turbulent flame speeds for large-hydrocarbon fuels are largely unknown. These values are needed to improve combustion models and enhance understanding of the physics and chemistry that control turbulent combustion of large-hydrocarbon fuels. The objective of this study is to measure the turbulent flame speed of large-hydrocarbon fuels and to identify key physics in the turbulent combustion of these fuels. This is motivated by the use of the turbulent flame speeds in modeling combustion in practical devices and the significant use of large-hydrocarbons in these devices. This research has broad implications for society and industry; both the Federal Aviation Administration and gas turbine engine companies have called for research on the turbulent flame speeds of large-hydrocarbon fuels. The turbulent flame speed in this work is defined as the global consumption speed, and is measured for three fuels on a turbulent Bunsen burner. The Reynolds number, turbulence intensity, preheat temperature, and equivalent ratio can be independently controlled using the burner. A conventional Jet-A fuel, known as A2, is used as a reference because of its common use in commercial and military aviation. A2 is compared to bi-modal and quadra-modal blends referred to as C1 and C5, respectively. These fuels are selected as they have similar heat releases and laminar flame speeds. Time-averaged line of site images of OH*, CH*, and CO₂* chemiluminescence are used to determine an the average flame front area. This flame area is used to determine the global consumption speed. The global consumption speed is measured for Reynolds number and equivalence ratio ranging between 5.000-10.000 and 0.7-1, respectively. Turbulence intensities are varied between 10% and 20% of the bulk flow velocity. The global consumption speed increases with turbulence intensity and Reynolds number for all fuels. Global consumption speeds for A2 and C5 match within 5% at all conditions. Conversely, the global consumption speed of C1 is up to 22% lower than A2 or C5. These results indicate the global consumption speed is sensitive to turbulent velocity fluctuations, bulk flow velocity, and fuel chemistry. These results together suggest the global consumption speed is additionally sensitive to flame stretch. Dimensional analysis is used to isolate and identify sensitivities of the global consumption speed to turbulent velocity fluctuations, bulk flow velocity, global stretch rate, and fuel chemistry. A clear sensitivity to fuel chemistry is observed and is affected by aromatic and alkane content. A2 and C5 have higher global consumptions speeds and increased stability; these fuels have shorter average hydrocarbon chain lengths and higher aro- matic content than C1. In addition, the global consumption speed is highly sensitive to turbulence intensity of the flow; the turbulent flame speed increases an average of 30% for all fuels between the minimum and maximum turbulence intensity cases. Results are attributed to a strong sensitivity of the global consumption speed to flame stretch and a strong coupling of turbulence and fuel chemistry effects. These conclusions agree with the available literature and provide a foundational understanding of the sensitivities of the global consumption speed for large-hydrocarbon fuels. Close

• 4128. [Article] Bioactive glass filled resin composites : mechanical properties and resistance to secondary tooth decay

  Dental resin composites are widely used in modern dentistry due to their aesthetic appearance. However, resin based restorations have inferior mechanical properties (fracture is the second reason for restorations ...

  Citation × Citation Citation Abstract Copy Title: Bioactive glass filled resin composites : mechanical properties and resistance to secondary tooth decay Author: Khvostenko, Dmytro Dental resin composites are widely used in modern dentistry due to their aesthetic appearance. However, resin based restorations have inferior mechanical properties (fracture is the second reason for restorations replacement) in comparison to alloy based composites and their antimicrobial properties still remain poor, leading to secondary tooth decay development on tooth-filling interface (which is the primary reason for restorations failure). In this work the Bioactive glass (BAG) was used as an antimicrobial filler. Experimental composites were prepared with 0-15 wt% BAG filler and 72-57 wt% silane treated silica glass, keeping a total filler content constant at 72 wt%. BAG composite's mechanical properties were examined, using 3-point bending beams for flexural strength measurement, pre-cracked compact-tension samples, C(T), for fracture toughness and fatigue crack growth evaluation. All mechanical properties were tested for different soaking treatments of the samples: 24 hours in DI water (all experiments) 2 months in sterile media (flexural test only) and 2 months in media with Streptococcus mutans bacteria (all experiemtns). All mechanical properties findings were compared to those ones of commercial Heliomolar composite. Main toughening mechanisms for BAG composites were evaluated post-test by SEM. The results showed that all mechanical properties for BAG composites were unaffected by increasing the filler content from 0 to 15 wt%. Moreover, all mechanical properties of BAG composites were significantly superior over Heliomolar composites. BAG composite's flexural strength properties were not affected by any of aging treatments and a slight decrease in fracture toughness and fatigue crack growth resistance was observed after 2 months soaking in media with bacteria. Main toughening mechanisms were related to BAG composite's increased filler, which resulted in more frequent crack deflection, and crack bridging at the crack tip and far away from it. In next phase of the research, a novel bioreactor and new test specimen type were developed, which allowed investigating the synergistic effect of cyclic loading and bacterial exposure on secondary tooth decay. The bioreactor was able to provide environment suitable for bacteria, similar to lab incubators. Teeth samples were machined into the disk shape (3 mm tall, 9 mm diameter), mainly consisting of dentin and the middle of sample was drilled and restored with 0 wt% BAG (0BAG) composite (2 mm deep, 5 mm diameter), introducing semi-circumferential gap between dentin and restoration of 10-30 microns. All samples were initially disinfected with 1% chloramine solution. Streptococcus mutans biofilm was grown over the samples and then they were placed in bioreactors and subjected to 1.5 Hz loading cycling at maximum load of 25% from breaking load and R=0.1 for 2 hours, followed by 4 hours resting at minimal load. The procedure was repeated for total of 2 weeks of an experiment, during which bacteria biofilm was constantly supplied with BHI media, carbon dioxide and 37oC temperature. After 2 weeks test, samples' biofilm viability was evaluated with live/dead staining kit and then, after fixing the biofilm on the samples in 4% gluteraldehyde, all samples were sectioned across the gap and stained with Gram Crysrtal Violet CAT+ dye , followed by fluorescence microscopy to reveal the depth of bacterial penetration down the gap. The depth of bacterial penetration of loaded samples was compared to one of non-loaded samples and results revealed a significantly deeper bacterial penetration for cyclically loaded samples versus non-loaded, thus, it was concluded that cyclic loading and bacterial exposure together aid secondary tooth decay propagation. In the last phase of this project the anti-microbial properties of BAG composites were evaluated. Using the same sample preparation technique and methods from the previous phase (except that now the composite was 15 wt% BAG, a.k.a 15BAG), we found out that bacterial penetration down the gap for 15BAG composite was significantly lower (almost 50% difference) in comparison to 0BAG composite, which made us confident to draw a conclusion that 15BAG composite possesses good antimicrobial properties and can be used for secondary tooth decay prevention. Title: Bioactive glass filled resin composites : mechanical properties and resistance to secondary tooth decay Author: Khvostenko, Dmytro Dental resin composites are widely used in modern dentistry due to their aesthetic appearance. However, resin based restorations have inferior mechanical properties (fracture is the second reason for restorations replacement) in comparison to alloy based composites and their antimicrobial properties still remain poor, leading to secondary tooth decay development on tooth-filling interface (which is the primary reason for restorations failure). In this work the Bioactive glass (BAG) was used as an antimicrobial filler. Experimental composites were prepared with 0-15 wt% BAG filler and 72-57 wt% silane treated silica glass, keeping a total filler content constant at 72 wt%. BAG composite's mechanical properties were examined, using 3-point bending beams for flexural strength measurement, pre-cracked compact-tension samples, C(T), for fracture toughness and fatigue crack growth evaluation. All mechanical properties were tested for different soaking treatments of the samples: 24 hours in DI water (all experiments) 2 months in sterile media (flexural test only) and 2 months in media with Streptococcus mutans bacteria (all experiemtns). All mechanical properties findings were compared to those ones of commercial Heliomolar composite. Main toughening mechanisms for BAG composites were evaluated post-test by SEM. The results showed that all mechanical properties for BAG composites were unaffected by increasing the filler content from 0 to 15 wt%. Moreover, all mechanical properties of BAG composites were significantly superior over Heliomolar composites. BAG composite's flexural strength properties were not affected by any of aging treatments and a slight decrease in fracture toughness and fatigue crack growth resistance was observed after 2 months soaking in media with bacteria. Main toughening mechanisms were related to BAG composite's increased filler, which resulted in more frequent crack deflection, and crack bridging at the crack tip and far away from it. In next phase of the research, a novel bioreactor and new test specimen type were developed, which allowed investigating the synergistic effect of cyclic loading and bacterial exposure on secondary tooth decay. The bioreactor was able to provide environment suitable for bacteria, similar to lab incubators. Teeth samples were machined into the disk shape (3 mm tall, 9 mm diameter), mainly consisting of dentin and the middle of sample was drilled and restored with 0 wt% BAG (0BAG) composite (2 mm deep, 5 mm diameter), introducing semi-circumferential gap between dentin and restoration of 10-30 microns. All samples were initially disinfected with 1% chloramine solution. Streptococcus mutans biofilm was grown over the samples and then they were placed in bioreactors and subjected to 1.5 Hz loading cycling at maximum load of 25% from breaking load and R=0.1 for 2 hours, followed by 4 hours resting at minimal load. The procedure was repeated for total of 2 weeks of an experiment, during which bacteria biofilm was constantly supplied with BHI media, carbon dioxide and 37oC temperature. After 2 weeks test, samples' biofilm viability was evaluated with live/dead staining kit and then, after fixing the biofilm on the samples in 4% gluteraldehyde, all samples were sectioned across the gap and stained with Gram Crysrtal Violet CAT+ dye , followed by fluorescence microscopy to reveal the depth of bacterial penetration down the gap. The depth of bacterial penetration of loaded samples was compared to one of non-loaded samples and results revealed a significantly deeper bacterial penetration for cyclically loaded samples versus non-loaded, thus, it was concluded that cyclic loading and bacterial exposure together aid secondary tooth decay propagation. In the last phase of this project the anti-microbial properties of BAG composites were evaluated. Using the same sample preparation technique and methods from the previous phase (except that now the composite was 15 wt% BAG, a.k.a 15BAG), we found out that bacterial penetration down the gap for 15BAG composite was significantly lower (almost 50% difference) in comparison to 0BAG composite, which made us confident to draw a conclusion that 15BAG composite possesses good antimicrobial properties and can be used for secondary tooth decay prevention. Close

• 4129. [Article] Studies on the inhibition of food-borne pathogens and spoilage bacteria by lactic acid starter cultures

  The ability of Streptococcus diacetilactis to inhibit a variety of food-borne pathogens and spoilage organisms in milk and broth cultures was demonstrated. Test organisms inhibited included Pseudomonas and ...

  Citation × Citation Citation Abstract Copy Title: Studies on the inhibition of food-borne pathogens and spoilage bacteria by lactic acid starter cultures Author: Daly, Charles The ability of Streptococcus diacetilactis to inhibit a variety of food-borne pathogens and spoilage organisms in milk and broth cultures was demonstrated. Test organisms inhibited included Pseudomonas and Alcaligenes species, Eschericia coli, Salmonella, Staphylococcus aureus, Clostridium perfringens and Vibrio parahaemolyticus. In general, approximately 99.0% and 99.9% inhibition was observed in milk and broth cultures, respectively. Streptococcus lactis, Streptococcus cremoris, Pediococcus cerevisiae and Lactobacillus plantarum also inhibited S. aureus in lactic broth. Possible practical applications of the observed inhibition were examined. S. diacetilactis prevented proteolysis in milk at 7. 5C by Pseudomonas fluorescens. S. aureus was inhibited greater than 99% in vanilla cream filling, ham sandwich spread, chicken gravy, soy milk and ground beef stored at 25C for 24 hr. Development of the Gram negative flora of ground beef was also inhibited greater than 99% after storage at 7.5C for 7 days. The mechanism of inhibition of S. aureus in lactic broth was examined with emphasis on the role of pH changes and acid production by S. diacetilactis. S. aureus did not grow in cell-free culture supernatants of S. diacetilactis grown in modified lactic broth (final pH 4.3 - 4.7). However, good growth was evident when the pH was adjusted towards neutrality. When the amounts of formic, acetic and lactic acids produced by S. diacetilactis were quantitatively determined and added to lactic broth, a similar pH dependent inhibition was observed. This inhibition was not as marked as that observed with cultures or cell-free supernatants of S. diacetilactis, suggesting that factors other than acid production were involved. Nutrient depletion and hydrogen peroxide did not contribute to the inhibition in this system. Enterotoxin B synthesis by S. aureus S6 and S. aureus ATCC 14458 was studied in Brain Heart Infusion broth (BHI) and N-Z Amine NAK broth (NAK). Toxin yields by S. aureus S6 were approximately 180 μg /ml and 100 μg/m1 in NAK and BHI, respectively at 30C and 150 rpm. Yields for strain 14458 were significantly lower. When the initial inoculum of S. aureus S6 was 4 x 10⁵ cells/ml, the addition of 0.5% glucose or 0.5% maltose initially repressed both toxin synthesis and the pH rise associated with toxin synthesis; however, after 72 hr of incubation, the pH rise and toxin produced were the same as occurred without added carbohydrate. Furthermore, addition of maltose, but not glucose, reduced the toxin yield of S. aureus ATCC 14458 by about 80% at 72 hr. When S. diacetilactis (initial inoculum 1 x 10⁷ cells/ml) was added to BHI containing 0. 5% glucose or 0. 5% maltose, no toxin synthesis or pH rise was observed when the initial inoculum of S. aureus was 4 x 10⁵ cells/ml. In plain BHI, no toxin was observed under these associative growth conditions and the pH remained constant at 6.6. Inhibition of toxin production in this system could be partially reversed by the addition of 0. 5% sodium pyruvate, sodium acetate or sodium succinate. When the initial inoculum of S. aureus was 4 x 10⁸ cells/ml, only partial or no inhibition of toxin production in the presence of S. diacetilactis (inoc ulum 1 x 10⁷ c ell s /m1) was observed. Substantial inhibition by S. diacetilactis was observed at this concentration when the medium was BHI + 0. 5% maltose but not when BHI + 0. 5% glucose was used. Inhibition of toxin production but not growth was evident in NAK + 1% glucose. Sodium citrate addition inhibited both growth and toxin production by S. aureus S6. The toxin yields of the S. aureus strains were greatly reduced when static incubation was used. Inhibition by S. diacetilactis was readily demonstrated under these conditions. Three commercially available starter cultures, Lactacel, Lactacel MC and Lactacel DS, were examined for their ability to control the growth of S. aureus during a simulated beaker sausage fermentation at 21C, 30C and 37C. Although differences between cultures were evident, all three gave greater than 99% inhibition after 50 hr of incubation at 30C and 37C. Inhibition was somewhat reduced (average of 97% at 50 hr) at 21C. Chemical acidulation with gluconodelta- lactone (0.75%) plus citric acid (0. 1 %) yielded good initial control in a similar process. However, on extended incubation up to 50 hr good growth of the pathogen occurred and the inhibition was only slight or none at this time for samples incubated at 30C and 37C; at 21C inhibition was approximately 97%. A combination of starter cultures and chemical acidulation gave approximately 99.99% inhibition of S. aureus at the three temperatures after 50 hr of incubation. Possible applications of these findings to the food industry are discussed. A greater role for the lactic acid bacteria in the area of food-safety is suggested. Title: Studies on the inhibition of food-borne pathogens and spoilage bacteria by lactic acid starter cultures Author: Daly, Charles The ability of Streptococcus diacetilactis to inhibit a variety of food-borne pathogens and spoilage organisms in milk and broth cultures was demonstrated. Test organisms inhibited included Pseudomonas and Alcaligenes species, Eschericia coli, Salmonella, Staphylococcus aureus, Clostridium perfringens and Vibrio parahaemolyticus. In general, approximately 99.0% and 99.9% inhibition was observed in milk and broth cultures, respectively. Streptococcus lactis, Streptococcus cremoris, Pediococcus cerevisiae and Lactobacillus plantarum also inhibited S. aureus in lactic broth. Possible practical applications of the observed inhibition were examined. S. diacetilactis prevented proteolysis in milk at 7. 5C by Pseudomonas fluorescens. S. aureus was inhibited greater than 99% in vanilla cream filling, ham sandwich spread, chicken gravy, soy milk and ground beef stored at 25C for 24 hr. Development of the Gram negative flora of ground beef was also inhibited greater than 99% after storage at 7.5C for 7 days. The mechanism of inhibition of S. aureus in lactic broth was examined with emphasis on the role of pH changes and acid production by S. diacetilactis. S. aureus did not grow in cell-free culture supernatants of S. diacetilactis grown in modified lactic broth (final pH 4.3 - 4.7). However, good growth was evident when the pH was adjusted towards neutrality. When the amounts of formic, acetic and lactic acids produced by S. diacetilactis were quantitatively determined and added to lactic broth, a similar pH dependent inhibition was observed. This inhibition was not as marked as that observed with cultures or cell-free supernatants of S. diacetilactis, suggesting that factors other than acid production were involved. Nutrient depletion and hydrogen peroxide did not contribute to the inhibition in this system. Enterotoxin B synthesis by S. aureus S6 and S. aureus ATCC 14458 was studied in Brain Heart Infusion broth (BHI) and N-Z Amine NAK broth (NAK). Toxin yields by S. aureus S6 were approximately 180 μg /ml and 100 μg/m1 in NAK and BHI, respectively at 30C and 150 rpm. Yields for strain 14458 were significantly lower. When the initial inoculum of S. aureus S6 was 4 x 10⁵ cells/ml, the addition of 0.5% glucose or 0.5% maltose initially repressed both toxin synthesis and the pH rise associated with toxin synthesis; however, after 72 hr of incubation, the pH rise and toxin produced were the same as occurred without added carbohydrate. Furthermore, addition of maltose, but not glucose, reduced the toxin yield of S. aureus ATCC 14458 by about 80% at 72 hr. When S. diacetilactis (initial inoculum 1 x 10⁷ cells/ml) was added to BHI containing 0. 5% glucose or 0. 5% maltose, no toxin synthesis or pH rise was observed when the initial inoculum of S. aureus was 4 x 10⁵ cells/ml. In plain BHI, no toxin was observed under these associative growth conditions and the pH remained constant at 6.6. Inhibition of toxin production in this system could be partially reversed by the addition of 0. 5% sodium pyruvate, sodium acetate or sodium succinate. When the initial inoculum of S. aureus was 4 x 10⁸ cells/ml, only partial or no inhibition of toxin production in the presence of S. diacetilactis (inoc ulum 1 x 10⁷ c ell s /m1) was observed. Substantial inhibition by S. diacetilactis was observed at this concentration when the medium was BHI + 0. 5% maltose but not when BHI + 0. 5% glucose was used. Inhibition of toxin production but not growth was evident in NAK + 1% glucose. Sodium citrate addition inhibited both growth and toxin production by S. aureus S6. The toxin yields of the S. aureus strains were greatly reduced when static incubation was used. Inhibition by S. diacetilactis was readily demonstrated under these conditions. Three commercially available starter cultures, Lactacel, Lactacel MC and Lactacel DS, were examined for their ability to control the growth of S. aureus during a simulated beaker sausage fermentation at 21C, 30C and 37C. Although differences between cultures were evident, all three gave greater than 99% inhibition after 50 hr of incubation at 30C and 37C. Inhibition was somewhat reduced (average of 97% at 50 hr) at 21C. Chemical acidulation with gluconodelta- lactone (0.75%) plus citric acid (0. 1 %) yielded good initial control in a similar process. However, on extended incubation up to 50 hr good growth of the pathogen occurred and the inhibition was only slight or none at this time for samples incubated at 30C and 37C; at 21C inhibition was approximately 97%. A combination of starter cultures and chemical acidulation gave approximately 99.99% inhibition of S. aureus at the three temperatures after 50 hr of incubation. Possible applications of these findings to the food industry are discussed. A greater role for the lactic acid bacteria in the area of food-safety is suggested. Close

• 4130. [Article] Transmission variation and loss of aphid transmissibility of bean yellow mosaic virus

  Several bean yellow mosaic virus (BYMV) strains, presumably not transmissible by aphids, were studied to determine the biological and environmental conditions which would possibly result in aphid transmission ...

  Citation × Citation Citation Abstract Copy Title: Transmission variation and loss of aphid transmissibility of bean yellow mosaic virus Author: Kamm, James A. Several bean yellow mosaic virus (BYMV) strains, presumably not transmissible by aphids, were studied to determine the biological and environmental conditions which would possibly result in aphid transmission of these strains. Investigations were made to study the effect of different aphid rearing conditions on the transmission frequency of BYMV. Also, the probing behavior of Myzus persicae (Sulzer) was studied in relation to transmission frequency of BYMV to test plants. Differences other than loss of transmissibility were found to account for the failure of aphids to transmit some BYMV strains. Five strains varied in ability to infect specific pea and bean varieties; all strains were aphid transmissible except BYMV III. BYMV I and II no longer produced systemic infection in Perfected Wales pea or Dwarf Horticultural bean although both strains produced local infection in inoculated leaves of Perfected Wales pea. Only BYMV y21 and III produced systemic infection in Dwarf Horticultural bean. The above changes in virus infectivity were attributed to virus mutation. Both Dwarf Horticultural bean and Perfected Wales pea are commonly used as differential hosts to identify legume viruses. BYMV and pea mosaic virus are distinguished only on the inability of pea mosaic virus to infect bean. Consequently, the validity of virus classification of legume viruses based on differential host reaction is questionable. In addition to the above variation, BYMV I and II required a high post-inoculation temperature to produce infection in Blue Lake bean; other strains were not affected under the same conditions. The host range of BYMV I, II, III, and IV was the same in the plants: Trifolium pretense L., Crotolaria spectabilis Roth., Trifolium subterranean L. variety Yarloop, Chenopodium amaranticolor Coste and Reyn., Glycine max (L.) Merr. variety Lincoln, Melilotus alba Desr., and Pisumm sativum L. variety Lincoln. BYMV III, maintained by mechanical transfer since 1963, was not transmitted to ten plant species in attempts with over 5000 aphids. Myzus persicae (Sulzer) failed to transmit BYMV III from five different species or varieties of source plants. This was interpreted as evidence that virus acquisition by aphids, due to the source plant, was not involved in loss of aphid transmissibility of BYMV III. Five aphid species and ten test plant species were used in an attempt to find a vector-host plant combination which would result in aphid transmission of BYMV III. Macrosiphm albifrons Essig and Acyrthosiphon pisum (Harris) finally transmitted BYMV III to Crotolaria spectabilis Roth. This was the first transmission of BYMV III after attempts with more than 5000 aphids. The return of aphid transmissibility in BYMV III could be explained only on the basis of virus mutation. Indirect evidence from two experiments suggested that aphid transmissible and non-transmissible forms of BYMV III were present in the stock culture when Macrosiphum albifrons first transmitted BYMV III. Aphids transmitted the isolate first transmitted by Macrosiphum albifrons at a higher frequency than the stock culture of BYMV III. A subsequent experiment indicated that almost any aphid would transmit BYMV III after return of aphid transmissibility. Transmission of BYMV IV by aphids reared on Chinese cabbage was compared to that of aphids reared on a chemically defined diet. The trend in frequency of transmission implied that aphids reared on the artificial diet were inferior in transmission of BYMV IV. The probing behavior of Myzus persicae on Pisum sativum and Phaseolus vulgaris was evaluated in relation to the transmission frequency of BYMV. Plant susceptibility of pea and bean was the same. Aphids made 40 percent more probes on bean than on pea in a 15 minute observation period. However, increased transmission to bean was not reflected by the greater number of probes. There was no evidence that transmission of BYMV was affected by observed differences in the probing behavior of Myzus persicae. Title: Transmission variation and loss of aphid transmissibility of bean yellow mosaic virus Author: Kamm, James A. Several bean yellow mosaic virus (BYMV) strains, presumably not transmissible by aphids, were studied to determine the biological and environmental conditions which would possibly result in aphid transmission of these strains. Investigations were made to study the effect of different aphid rearing conditions on the transmission frequency of BYMV. Also, the probing behavior of Myzus persicae (Sulzer) was studied in relation to transmission frequency of BYMV to test plants. Differences other than loss of transmissibility were found to account for the failure of aphids to transmit some BYMV strains. Five strains varied in ability to infect specific pea and bean varieties; all strains were aphid transmissible except BYMV III. BYMV I and II no longer produced systemic infection in Perfected Wales pea or Dwarf Horticultural bean although both strains produced local infection in inoculated leaves of Perfected Wales pea. Only BYMV y21 and III produced systemic infection in Dwarf Horticultural bean. The above changes in virus infectivity were attributed to virus mutation. Both Dwarf Horticultural bean and Perfected Wales pea are commonly used as differential hosts to identify legume viruses. BYMV and pea mosaic virus are distinguished only on the inability of pea mosaic virus to infect bean. Consequently, the validity of virus classification of legume viruses based on differential host reaction is questionable. In addition to the above variation, BYMV I and II required a high post-inoculation temperature to produce infection in Blue Lake bean; other strains were not affected under the same conditions. The host range of BYMV I, II, III, and IV was the same in the plants: Trifolium pretense L., Crotolaria spectabilis Roth., Trifolium subterranean L. variety Yarloop, Chenopodium amaranticolor Coste and Reyn., Glycine max (L.) Merr. variety Lincoln, Melilotus alba Desr., and Pisumm sativum L. variety Lincoln. BYMV III, maintained by mechanical transfer since 1963, was not transmitted to ten plant species in attempts with over 5000 aphids. Myzus persicae (Sulzer) failed to transmit BYMV III from five different species or varieties of source plants. This was interpreted as evidence that virus acquisition by aphids, due to the source plant, was not involved in loss of aphid transmissibility of BYMV III. Five aphid species and ten test plant species were used in an attempt to find a vector-host plant combination which would result in aphid transmission of BYMV III. Macrosiphm albifrons Essig and Acyrthosiphon pisum (Harris) finally transmitted BYMV III to Crotolaria spectabilis Roth. This was the first transmission of BYMV III after attempts with more than 5000 aphids. The return of aphid transmissibility in BYMV III could be explained only on the basis of virus mutation. Indirect evidence from two experiments suggested that aphid transmissible and non-transmissible forms of BYMV III were present in the stock culture when Macrosiphum albifrons first transmitted BYMV III. Aphids transmitted the isolate first transmitted by Macrosiphum albifrons at a higher frequency than the stock culture of BYMV III. A subsequent experiment indicated that almost any aphid would transmit BYMV III after return of aphid transmissibility. Transmission of BYMV IV by aphids reared on Chinese cabbage was compared to that of aphids reared on a chemically defined diet. The trend in frequency of transmission implied that aphids reared on the artificial diet were inferior in transmission of BYMV IV. The probing behavior of Myzus persicae on Pisum sativum and Phaseolus vulgaris was evaluated in relation to the transmission frequency of BYMV. Plant susceptibility of pea and bean was the same. Aphids made 40 percent more probes on bean than on pea in a 15 minute observation period. However, increased transmission to bean was not reflected by the greater number of probes. There was no evidence that transmission of BYMV was affected by observed differences in the probing behavior of Myzus persicae. Close