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• 41. [Article] Understanding the Joint Behavior of Temperature and Precipitation for Climate Change Impact Studies

  The multiple downscaled-scenario products allow us to assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Probabilistic assessments of both climatic ...

  Citation × Citation Citation Abstract Copy Title: Understanding the Joint Behavior of Temperature and Precipitation for Climate Change Impact Studies Author: Rana, Arun, Moradkhani, Hamid, Qin, Yueyue Year: 2016 The multiple downscaled-scenario products allow us to assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Probabilistic assessments of both climatic variables help better understand the interdependence of the two, and thus in-turn help in assessing the future with confidence. In the present study, we use ensemble of statistically downscaled precipitation and temperature from various models. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State University. The multi-model ensemble of both precipitation and temperature is evaluated for dry and wet periods for 10 sub-basins across Columbia River Basin (CRB). Thereafter, Copula is applied to establish the joint distribution of two variables on multi-model ensemble data. The joint distribution is then used to estimate the change in trends of said variables in future, along with estimation of the probabilities of the given change. The joint distribution trends varies, but certainly positive, for dry and wet periods in sub-basins of CRB. Dry season, generally, is indicating a higher positive change in precipitation than temperature (as compared to historical) across sub-basins with wet season inferring otherwise. Probabilities of changes in future, as estimated from the joint distribution indicate varied degrees and forms during dry season whereas the wet season is rather constant across all the sub-basins. Title: Understanding the Joint Behavior of Temperature and Precipitation for Climate Change Impact Studies Author: Rana, Arun, Moradkhani, Hamid, Qin, Yueyue Year: 2016 The multiple downscaled-scenario products allow us to assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Probabilistic assessments of both climatic variables help better understand the interdependence of the two, and thus in-turn help in assessing the future with confidence. In the present study, we use ensemble of statistically downscaled precipitation and temperature from various models. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State University. The multi-model ensemble of both precipitation and temperature is evaluated for dry and wet periods for 10 sub-basins across Columbia River Basin (CRB). Thereafter, Copula is applied to establish the joint distribution of two variables on multi-model ensemble data. The joint distribution is then used to estimate the change in trends of said variables in future, along with estimation of the probabilities of the given change. The joint distribution trends varies, but certainly positive, for dry and wet periods in sub-basins of CRB. Dry season, generally, is indicating a higher positive change in precipitation than temperature (as compared to historical) across sub-basins with wet season inferring otherwise. Probabilities of changes in future, as estimated from the joint distribution indicate varied degrees and forms during dry season whereas the wet season is rather constant across all the sub-basins. Close

• 42. [Article] Interactive Physiological Responses of Nile Tilapia to Salinity- and Temperature-induced Stress: Quantifying the Regulation of Apoptosis and Cell Cycle Arrest in Oreochromis Niloticus

  Nile tilapia provide an ideal model to study the accumulation of climate change-induced stressors due to their habitat in tropical freshwater systems that are susceptible to salt water invasion and temperature ...

  Citation × Citation Citation Abstract Copy Title: Interactive Physiological Responses of Nile Tilapia to Salinity- and Temperature-induced Stress: Quantifying the Regulation of Apoptosis and Cell Cycle Arrest in Oreochromis Niloticus Author: McGuire, Charlee Year: 2017 Nile tilapia provide an ideal model to study the accumulation of climate change-induced stressors due to their habitat in tropical freshwater systems that are susceptible to salt water invasion and temperature fluctuation due to sea level rise. This study investigates the physiological responses of Nile tilapia to salinity- and temperature-induced stress to identify the interactive effects of simultaneous stressors on the cell cycle. Proteins indicative of cell cycle activity and arrest were quantified in the tissues of Nile tilapia exposed to various environmental conditions varying by temperature and salinity. Dot Blotting was utilized to measure Gadd45 while Western Blotting was used to confirm the identity of the protein. Results from previous investigations in the Buckley lab were also utilized to compare the expression patterns of Gadd45 to relevant cell activity proteins p53 and PCNA. Of the three proteins under scrutiny, a significant change in expression of p53 was observed for the interaction of salinity- and temperature- induced stress, while full strength saltwater treatment alone was found to have a significant impact on the expression of p53, Gadd45 and PCNA. These findings can be used in collaboration with existing studies to describe the coordination of apoptotic pathways in Nile tilapia and other non-mammalian species, as well as to create policy on how to conserve this important species effectively both in the wild and in fisheries for aquaculture, commercial and public health initiatives in response to global climate change. Title: Interactive Physiological Responses of Nile Tilapia to Salinity- and Temperature-induced Stress: Quantifying the Regulation of Apoptosis and Cell Cycle Arrest in Oreochromis Niloticus Author: McGuire, Charlee Year: 2017 Nile tilapia provide an ideal model to study the accumulation of climate change-induced stressors due to their habitat in tropical freshwater systems that are susceptible to salt water invasion and temperature fluctuation due to sea level rise. This study investigates the physiological responses of Nile tilapia to salinity- and temperature-induced stress to identify the interactive effects of simultaneous stressors on the cell cycle. Proteins indicative of cell cycle activity and arrest were quantified in the tissues of Nile tilapia exposed to various environmental conditions varying by temperature and salinity. Dot Blotting was utilized to measure Gadd45 while Western Blotting was used to confirm the identity of the protein. Results from previous investigations in the Buckley lab were also utilized to compare the expression patterns of Gadd45 to relevant cell activity proteins p53 and PCNA. Of the three proteins under scrutiny, a significant change in expression of p53 was observed for the interaction of salinity- and temperature- induced stress, while full strength saltwater treatment alone was found to have a significant impact on the expression of p53, Gadd45 and PCNA. These findings can be used in collaboration with existing studies to describe the coordination of apoptotic pathways in Nile tilapia and other non-mammalian species, as well as to create policy on how to conserve this important species effectively both in the wild and in fisheries for aquaculture, commercial and public health initiatives in response to global climate change. Close

• 43. [Article] Utilizing Humidity and Temperature Data to Advance Monitoring and Prediction of Meteorological Drought

  The fraction of land area over the Continental United States experiencing extreme hot and dry conditions has been increasing over the past several decades, consistent with expectation from anthropogenic ...

  Citation × Citation Citation Abstract Copy Title: Utilizing Humidity and Temperature Data to Advance Monitoring and Prediction of Meteorological Drought Author: Behrangi, Ali, Loikith, Paul C., Fetzer, Eric J., Nguyen, Hai M., Granger, Stephanie L. Year: 2015 The fraction of land area over the Continental United States experiencing extreme hot and dry conditions has been increasing over the past several decades, consistent with expectation from anthropogenic climate change. A clear concurrent change in precipitation, however, has not been confirmed. Vapor pressure deficit (VPD), combining temperature and humidity, is utilized here as an indicator of the background atmospheric conditions associated with meteorological drought. Furthermore, atmospheric conditions associated with warm season drought events are assessed by partitioning associated VPD anomalies into the temperature and humidity components. This approach suggests that the concurrence of anomalously high temperature and low humidity was an important driver of the rapid development and evolution of the exceptionally severe 2011 Texas and the 2012 Great Plains droughts. By classification of a decade of extreme drought events and tracking them back in time, it was found that near surface atmospheric temperature and humidity add essential information to the commonly used precipitation-based drought indicators and can advance efforts to determine the timing of drought onset and its severity. Title: Utilizing Humidity and Temperature Data to Advance Monitoring and Prediction of Meteorological Drought Author: Behrangi, Ali, Loikith, Paul C., Fetzer, Eric J., Nguyen, Hai M., Granger, Stephanie L. Year: 2015 The fraction of land area over the Continental United States experiencing extreme hot and dry conditions has been increasing over the past several decades, consistent with expectation from anthropogenic climate change. A clear concurrent change in precipitation, however, has not been confirmed. Vapor pressure deficit (VPD), combining temperature and humidity, is utilized here as an indicator of the background atmospheric conditions associated with meteorological drought. Furthermore, atmospheric conditions associated with warm season drought events are assessed by partitioning associated VPD anomalies into the temperature and humidity components. This approach suggests that the concurrence of anomalously high temperature and low humidity was an important driver of the rapid development and evolution of the exceptionally severe 2011 Texas and the 2012 Great Plains droughts. By classification of a decade of extreme drought events and tracking them back in time, it was found that near surface atmospheric temperature and humidity add essential information to the commonly used precipitation-based drought indicators and can advance efforts to determine the timing of drought onset and its severity. Close

• 44. [Article] Micrometeorological Simulations to Predict the Impacts of Heat Mitigation Strategies on Pedestrian Thermal Comfort in a Los Angeles Neighborhood

  The urban heat island impacts the thermal comfort of pedestrians in cities. In this paper, the effects of four heat mitigation strategies on micrometeorology and the thermal comfort of pedestrians were ...

  Citation × Citation Citation Abstract Copy Title: Micrometeorological Simulations to Predict the Impacts of Heat Mitigation Strategies on Pedestrian Thermal Comfort in a Los Angeles Neighborhood Author: Taleghani, Mohammad, Sailor, David J., Ban-Weiss, George A. Year: 2016 The urban heat island impacts the thermal comfort of pedestrians in cities. In this paper, the effects of four heat mitigation strategies on micrometeorology and the thermal comfort of pedestrians were simulated for a neighborhood in eastern Los Angeles County. The strategies investigated include solar reflective ‘cool roofs’, vegetative ‘green roofs’, solar reflective ‘cool pavements’, and increased streetlevel trees. Aseries of micrometeorological simulations for an extreme heat day were carried out assuming widespread adoption of each mitigation strategy. Comparing each simulation to the control simulation assuming current land cover for the neighborhood showed that additional street-trees and cool pavements reduced 1.5mair temperature, while cool and green roofs mostly provided cooling at heights above pedestrian level. However, cool pavements increased reflected sunlight from the ground to pedestrians at a set of unshaded receptor locations. This reflected radiation intensified the mean radiant temperature and consequently increased physiological equivalent temperature (PET) by 2.2 °Cduring the day, reducing the thermal comfort of pedestrians. At another set of receptor locations that were on average 5mfrom roadways and underneath preexisting tree cover, cool pavements caused significant reductions in surface air temperatures and small changes in mean radiant temperature during the day, leading to decreases in PET of 1.1 °C, and consequent improvements in thermal comfort. For improving thermal comfort of pedestrians during the afternoon in unshaded locations, adding street trees was found to be the most effective strategy. However, afternoon thermal comfort improvements in already shaded locations adjacent to streets were most significant for cool pavements. Green and cool roofs showed the lowest impact on the thermal comfort of pedestrians since they modify the energy balance at roof level, above the height of pedestrians. Title: Micrometeorological Simulations to Predict the Impacts of Heat Mitigation Strategies on Pedestrian Thermal Comfort in a Los Angeles Neighborhood Author: Taleghani, Mohammad, Sailor, David J., Ban-Weiss, George A. Year: 2016 The urban heat island impacts the thermal comfort of pedestrians in cities. In this paper, the effects of four heat mitigation strategies on micrometeorology and the thermal comfort of pedestrians were simulated for a neighborhood in eastern Los Angeles County. The strategies investigated include solar reflective ‘cool roofs’, vegetative ‘green roofs’, solar reflective ‘cool pavements’, and increased streetlevel trees. Aseries of micrometeorological simulations for an extreme heat day were carried out assuming widespread adoption of each mitigation strategy. Comparing each simulation to the control simulation assuming current land cover for the neighborhood showed that additional street-trees and cool pavements reduced 1.5mair temperature, while cool and green roofs mostly provided cooling at heights above pedestrian level. However, cool pavements increased reflected sunlight from the ground to pedestrians at a set of unshaded receptor locations. This reflected radiation intensified the mean radiant temperature and consequently increased physiological equivalent temperature (PET) by 2.2 °Cduring the day, reducing the thermal comfort of pedestrians. At another set of receptor locations that were on average 5mfrom roadways and underneath preexisting tree cover, cool pavements caused significant reductions in surface air temperatures and small changes in mean radiant temperature during the day, leading to decreases in PET of 1.1 °C, and consequent improvements in thermal comfort. For improving thermal comfort of pedestrians during the afternoon in unshaded locations, adding street trees was found to be the most effective strategy. However, afternoon thermal comfort improvements in already shaded locations adjacent to streets were most significant for cool pavements. Green and cool roofs showed the lowest impact on the thermal comfort of pedestrians since they modify the energy balance at roof level, above the height of pedestrians. Close

• 45. [Article] A Statistical Investigation of Lower Columbia River Water Temperature, 1915-2003

  The Columbia River is home to anadromous salmon populations that migrate upriver every year to spawn. These fish require cool water temperatures (Tw) to survive. In recent years, high summer Tw in the ...

  Citation × Citation Citation Abstract Copy Title: A Statistical Investigation of Lower Columbia River Water Temperature, 1915-2003 Author: Overman, Corina Christina Mae Year: 2017 The Columbia River is home to anadromous salmon populations that migrate upriver every year to spawn. These fish require cool water temperatures (Tw) to survive. In recent years, high summer Tw in the Columbia River has caused increased mortality of salmon. Different possible explanations for increased Tw include climate change, deforestation, and decreased summertime streamflow (Q) due to dams. In this study, robust linear regression models of Tw based on air temperature (Ta) and Q were developed to examine the change in Tw over time. The data was separated into an historical period (1938-1956) and a modern period (1977-2003). Seasonal regression models were used for May through October (summer) and November through April (winter) for each period. Comparison of these models showed that Tw has become less sensitive to recent atmospheric heating and cooling. By contrast, analysis suggested that Tw has become more sensitive to variations in Q. Of the 1.5ºC increase in maximum summertime Tw, approximately 1.3ºC was due to dams and reservoir management based on changes in regression coefficients and average Q. A smaller, 0.2ºC change was estimated to be caused by increasing Ta since the mid-20th century. While average maximum Tw has increased, both the statistical model and data suggest that the variability in Tw from its climatological average has decreased, probably due to reservoir management. Title: A Statistical Investigation of Lower Columbia River Water Temperature, 1915-2003 Author: Overman, Corina Christina Mae Year: 2017 The Columbia River is home to anadromous salmon populations that migrate upriver every year to spawn. These fish require cool water temperatures (Tw) to survive. In recent years, high summer Tw in the Columbia River has caused increased mortality of salmon. Different possible explanations for increased Tw include climate change, deforestation, and decreased summertime streamflow (Q) due to dams. In this study, robust linear regression models of Tw based on air temperature (Ta) and Q were developed to examine the change in Tw over time. The data was separated into an historical period (1938-1956) and a modern period (1977-2003). Seasonal regression models were used for May through October (summer) and November through April (winter) for each period. Comparison of these models showed that Tw has become less sensitive to recent atmospheric heating and cooling. By contrast, analysis suggested that Tw has become more sensitive to variations in Q. Of the 1.5ºC increase in maximum summertime Tw, approximately 1.3ºC was due to dams and reservoir management based on changes in regression coefficients and average Q. A smaller, 0.2ºC change was estimated to be caused by increasing Ta since the mid-20th century. While average maximum Tw has increased, both the statistical model and data suggest that the variability in Tw from its climatological average has decreased, probably due to reservoir management. Close

• 46. [Article] 3D Numerical Temperature Model Development and Calibration for Lakes and Reservoirs: A Case Study

  A 3D hydrodynamic and temperature numerical model was developed and calibrated for Lake Chaplain, Washington, USA. The governing equations are the continuity equation, free surface equation, momentum equation, ...

  Citation × Citation Citation Abstract Copy Title: 3D Numerical Temperature Model Development and Calibration for Lakes and Reservoirs: A Case Study Author: Al-Zubaidi, Hussein A. M., Wells, Scott A. Year: 2017 A 3D hydrodynamic and temperature numerical model was developed and calibrated for Lake Chaplain, Washington, USA. The governing equations are the continuity equation, free surface equation, momentum equation, and conservation equation of transport. The model employs the semi-implicit finite difference scheme to solve the governing equations and higher order schemes (QUICK and Quickest) for mass and heat transport in contrast to simpler but more diffusive first order UPWIND scheme. A unique feature of the 3D numerical solution of the model free surface equation is that the solution uses a tri-diagonal matrix form rather than a more common pentadiagonal matrix. The surface heat exchange and turbulence structure were based on the CE-QUAL-W2 model. Comparisons in water surface levels and temperature vertical profiles between model predictions and data were performed using different advective transport schemes. The model matched data with good error statistics. Title: 3D Numerical Temperature Model Development and Calibration for Lakes and Reservoirs: A Case Study Author: Al-Zubaidi, Hussein A. M., Wells, Scott A. Year: 2017 A 3D hydrodynamic and temperature numerical model was developed and calibrated for Lake Chaplain, Washington, USA. The governing equations are the continuity equation, free surface equation, momentum equation, and conservation equation of transport. The model employs the semi-implicit finite difference scheme to solve the governing equations and higher order schemes (QUICK and Quickest) for mass and heat transport in contrast to simpler but more diffusive first order UPWIND scheme. A unique feature of the 3D numerical solution of the model free surface equation is that the solution uses a tri-diagonal matrix form rather than a more common pentadiagonal matrix. The surface heat exchange and turbulence structure were based on the CE-QUAL-W2 model. Comparisons in water surface levels and temperature vertical profiles between model predictions and data were performed using different advective transport schemes. The model matched data with good error statistics. Close

• 47. [Article] Olivine Crystallization Depths within Kilauea's Lower East Rift Zone: The Use of Rehomogenized Melt Inclusions to Interpret Magma Transport, Storage, and Energetic Fountaining

  H2O and CO2 concentrations in olivine-hosted melt inclusions, assuming vapor saturation at the time of trapping, can be used to estimate crystallization depths for the olivine host. Estimating the true ...

  Citation × Citation Citation Abstract Copy Title: Olivine Crystallization Depths within Kilauea's Lower East Rift Zone: The Use of Rehomogenized Melt Inclusions to Interpret Magma Transport, Storage, and Energetic Fountaining Author: Tuohy, Robin Year: 2014 H2O and CO2 concentrations in olivine-hosted melt inclusions, assuming vapor saturation at the time of trapping, can be used to estimate crystallization depths for the olivine host. Estimating the true CO2 in melt inclusions is difficult, as much is lost to shrinkage bubbles, which form upon post-entrapment cooling and crystallization. Reheating olivine to temperatures above the melt inclusion trapping temperature and then quenching rapidly can restore CO2 to the glass because the CO2 in the bubble redissolves at high temperature. Previous work has established that olivine crystallization for the1959 Kilauea Iki eruption took place in the shallow summit reservoir, but crystallization depths have not been established for the rift extension of the eruption, at Kapoho. The new data presented here suggest that the most primitive Kilauea Iki component bypassed the summit reservoir for the east rift zone prior to the start of the eruption and was later erupted at Kapoho. Title: Olivine Crystallization Depths within Kilauea's Lower East Rift Zone: The Use of Rehomogenized Melt Inclusions to Interpret Magma Transport, Storage, and Energetic Fountaining Author: Tuohy, Robin Year: 2014 H2O and CO2 concentrations in olivine-hosted melt inclusions, assuming vapor saturation at the time of trapping, can be used to estimate crystallization depths for the olivine host. Estimating the true CO2 in melt inclusions is difficult, as much is lost to shrinkage bubbles, which form upon post-entrapment cooling and crystallization. Reheating olivine to temperatures above the melt inclusion trapping temperature and then quenching rapidly can restore CO2 to the glass because the CO2 in the bubble redissolves at high temperature. Previous work has established that olivine crystallization for the1959 Kilauea Iki eruption took place in the shallow summit reservoir, but crystallization depths have not been established for the rift extension of the eruption, at Kapoho. The new data presented here suggest that the most primitive Kilauea Iki component bypassed the summit reservoir for the east rift zone prior to the start of the eruption and was later erupted at Kapoho. Close

• 48. [Article] The Geography of Glaciers and Perennial Snowfields in the American West

  A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey ...

  Citation × Citation Citation Abstract Copy Title: The Geography of Glaciers and Perennial Snowfields in the American West Author: Fountain, Andrew G., Glenn, Bryce, Basagic, Hassan J. Year: 2017 A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is estimated at ±9% for area and ±20% for volume. Two populations of G&PS were identified based on air temperature and precipitation. The larger is found in a maritime climate of the Pacific Northwest, characterized by warm winter air temperatures and high winter precipitation (~2100 mm). The other population is continental in climate, characterized by cold winter air temperatures, relatively low winter precipitation (~880 mm), and located at higher elevations elsewhere. The G&PS in the Pacific Northwest, especially in the Olympic Mountains, are particularly vulnerable to warming winter air temperatures that will change the phase of winter precipitation from snow to rain, further accelerating glacier shrinkage in the future. Comparison with a recent inventory suggests that the total G&PS area in the American West may have decreased by as much as 39% since the mid-20th century. Title: The Geography of Glaciers and Perennial Snowfields in the American West Author: Fountain, Andrew G., Glenn, Bryce, Basagic, Hassan J. Year: 2017 A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is estimated at ±9% for area and ±20% for volume. Two populations of G&PS were identified based on air temperature and precipitation. The larger is found in a maritime climate of the Pacific Northwest, characterized by warm winter air temperatures and high winter precipitation (~2100 mm). The other population is continental in climate, characterized by cold winter air temperatures, relatively low winter precipitation (~880 mm), and located at higher elevations elsewhere. The G&PS in the Pacific Northwest, especially in the Olympic Mountains, are particularly vulnerable to warming winter air temperatures that will change the phase of winter precipitation from snow to rain, further accelerating glacier shrinkage in the future. Comparison with a recent inventory suggests that the total G&PS area in the American West may have decreased by as much as 39% since the mid-20th century. Close

• 49. [Article] A Study of Microwave curing of Underfill using Open and Closed microwave ovens

  As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed ...

  Citation × Citation Citation Abstract Copy Title: A Study of Microwave curing of Underfill using Open and Closed microwave ovens Author: Thakare, Aditya Year: 2015 As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed up the manufacturing processes, new and novel approaches are trying to change certain aspects of it. Microwaves have been tried as an alternative to conventional ovens in the curing of the polymers used as underfills and encapsulants in integrated circuits packages. Microwaves however being electromagnetic waves have non uniform energy distribution in different settings, causing burning or incomplete cure of polymers. In this study, we compare the two main types of microwaves proposed to perform the task of curing the polymers. To limit the study and obtain comparable results, both microwaves were limited to propagate in a single mode, TE10. The first is a closed microwave cavity using air as the propagation medium, and the second is an open microwave oven with a PTFE cavity that uses an evanescent field to provide energy. The open air cavity was studied with different orientations of a substrate placed inside it so as to find the best case scenario in the curing process. This scenario was then compared with the best case scenario found for a sample cured in an evanescent field. This comparison yielded results showing an advantage of the open microwave in maximum field present, thus leading to higher localized energy absorption and temperatures in the substrate, however this case also lead to a higher temperature gradient. The substrate cured in the closed microwave has a lower temperature gradient, but also a lower maximum field which leads to slower cure. In the TE10 mode therefore, a closed microwave has an overall advantage as the heating process is only slightly slower than that of an open cavity, but the temperature gradient in this case is significantly lower. Title: A Study of Microwave curing of Underfill using Open and Closed microwave ovens Author: Thakare, Aditya Year: 2015 As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed up the manufacturing processes, new and novel approaches are trying to change certain aspects of it. Microwaves have been tried as an alternative to conventional ovens in the curing of the polymers used as underfills and encapsulants in integrated circuits packages. Microwaves however being electromagnetic waves have non uniform energy distribution in different settings, causing burning or incomplete cure of polymers. In this study, we compare the two main types of microwaves proposed to perform the task of curing the polymers. To limit the study and obtain comparable results, both microwaves were limited to propagate in a single mode, TE10. The first is a closed microwave cavity using air as the propagation medium, and the second is an open microwave oven with a PTFE cavity that uses an evanescent field to provide energy. The open air cavity was studied with different orientations of a substrate placed inside it so as to find the best case scenario in the curing process. This scenario was then compared with the best case scenario found for a sample cured in an evanescent field. This comparison yielded results showing an advantage of the open microwave in maximum field present, thus leading to higher localized energy absorption and temperatures in the substrate, however this case also lead to a higher temperature gradient. The substrate cured in the closed microwave has a lower temperature gradient, but also a lower maximum field which leads to slower cure. In the TE10 mode therefore, a closed microwave has an overall advantage as the heating process is only slightly slower than that of an open cavity, but the temperature gradient in this case is significantly lower. Close

• 50. [Article] Nanosilver Rainbow: A Rapid and Facile Method to Tune Different Colours of Nanosilver Through the Controlled Synthesis of Stable Spherical Silver Nanoparticles

  A rapid and simple one-pot reaction to synthesize stable, spherically shaped silver nanoparticles (AgNps) of different sizes producing distinct optical properties in aqueous solution at ambient temperature ...

  Citation × Citation Citation Abstract Copy Title: Nanosilver Rainbow: A Rapid and Facile Method to Tune Different Colours of Nanosilver Through the Controlled Synthesis of Stable Spherical Silver Nanoparticles Author: Mendis, Pramujitha, de Silva, Rohini M., Nalin de Silva, K. M., Wijenayaka, Lahiru A., Jayawardana, Kalana, Yan, Mingdi Year: 2016 A rapid and simple one-pot reaction to synthesize stable, spherically shaped silver nanoparticles (AgNps) of different sizes producing distinct optical properties in aqueous solution at ambient temperature has been developed. Each system contains various sizes of silver nanoparticles showing rainbow colours with the peak wavelength of the absorption spectra ranging from 400 to 750 nm. Seven different colours of nano silver were developed through the controlled synthesis of spherical silver nanoparticles using silver nitrate as the metal precursor. Sodium borohydride was used as the main reducing agent and trisodium citrate and hydrazine sulphate were used as the stabilizing and auxiliary reducing agents respectively. The colour of the solution was controlled by varying the concentrations of reagents and the optimum conditions for all the colours are reported. Characterization of silver nanoparticles was carried out using UV-visible spectrophotometry and Transmission Electron Microscopy (TEM). Factors affecting the formation of different sizes of silver nanoparticles, such as silver nitrate concentration, reducing agent concentrations, reaction temperature and reaction pH are also reported. The stability of these coloured silver colloidal solutions was also investigated at different temperatures and the most stable temperature was found to be 4 °C, while the optimum pH to synthesize distinctively coloured silver nanoparticles was found to be in the range of 7–8. The outlined procedure provides a rapid, facile and reproducible synthetic route to spherical AgNps of varying size and ensuing optical properties. Thus, this method is certain to find value in the many applications where size tunability of AgNps is desired. Title: Nanosilver Rainbow: A Rapid and Facile Method to Tune Different Colours of Nanosilver Through the Controlled Synthesis of Stable Spherical Silver Nanoparticles Author: Mendis, Pramujitha, de Silva, Rohini M., Nalin de Silva, K. M., Wijenayaka, Lahiru A., Jayawardana, Kalana, Yan, Mingdi Year: 2016 A rapid and simple one-pot reaction to synthesize stable, spherically shaped silver nanoparticles (AgNps) of different sizes producing distinct optical properties in aqueous solution at ambient temperature has been developed. Each system contains various sizes of silver nanoparticles showing rainbow colours with the peak wavelength of the absorption spectra ranging from 400 to 750 nm. Seven different colours of nano silver were developed through the controlled synthesis of spherical silver nanoparticles using silver nitrate as the metal precursor. Sodium borohydride was used as the main reducing agent and trisodium citrate and hydrazine sulphate were used as the stabilizing and auxiliary reducing agents respectively. The colour of the solution was controlled by varying the concentrations of reagents and the optimum conditions for all the colours are reported. Characterization of silver nanoparticles was carried out using UV-visible spectrophotometry and Transmission Electron Microscopy (TEM). Factors affecting the formation of different sizes of silver nanoparticles, such as silver nitrate concentration, reducing agent concentrations, reaction temperature and reaction pH are also reported. The stability of these coloured silver colloidal solutions was also investigated at different temperatures and the most stable temperature was found to be 4 °C, while the optimum pH to synthesize distinctively coloured silver nanoparticles was found to be in the range of 7–8. The outlined procedure provides a rapid, facile and reproducible synthetic route to spherical AgNps of varying size and ensuing optical properties. Thus, this method is certain to find value in the many applications where size tunability of AgNps is desired. Close