The Experts below are selected from a list of 5295 Experts worldwide ranked by ideXlab platform
M. Duignan - One of the best experts on this subject based on the ideXlab platform.
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Resorcinol-Formaldehyde Ion Exchange Resin Chemistry for High Level Waste Treatment -10161
2020Co-Authors: M. Duignan, Charles A NashAbstract:ABSTRACT A principal goal at the Savannah River Site is to safely dispose of the large volume of liquid nuclear waste held in many storage tanks. In-tank ion exchange technology is being considered for cesium removal using a polymer Resin made of resorcinol formaldehyde that has been engineered into microspheres. The waste under study is generally lower in potassium and organic components than Hanford waste; therefore, the Resin performance was evaluated with actual dissolved salt waste. The ion exchange performance and Resin Chemistry results are discussed
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RESORCINOL-FORMALDEHYDE ION EXCHANGE Resin Chemistry FOR HIGH LEVEL WASTE TREATMENT
Waste Management, 2010Co-Authors: C. Nash, M. DuignanAbstract:A principal goal at the Savannah River Site is to safely dispose of the large volume of liquid nuclear waste held in many storage tanks. In-tank ion exchange technology is being considered for cesium removal using a polymer Resin made of resorcinol formaldehyde that has been engineered into microspheres. The waste under study is generally lower in potassium and organic components than Hanford waste; therefore, the Resin performance was evaluated with actual dissolved salt waste. The ion exchange performance and Resin Chemistry results are discussed.
C. Nash - One of the best experts on this subject based on the ideXlab platform.
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RESORCINOL-FORMALDEHYDE ION EXCHANGE Resin Chemistry FOR HIGH LEVEL WASTE TREATMENT
Waste Management, 2010Co-Authors: C. Nash, M. DuignanAbstract:A principal goal at the Savannah River Site is to safely dispose of the large volume of liquid nuclear waste held in many storage tanks. In-tank ion exchange technology is being considered for cesium removal using a polymer Resin made of resorcinol formaldehyde that has been engineered into microspheres. The waste under study is generally lower in potassium and organic components than Hanford waste; therefore, the Resin performance was evaluated with actual dissolved salt waste. The ion exchange performance and Resin Chemistry results are discussed.
J Fisher - One of the best experts on this subject based on the ideXlab platform.
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multiple initiators and dyes for continuous digital light processing cdlp additive manufacture of resorbable bone tissue engineering scaffolds a new method and new material to fabricate resorbable scaffold for bone tissue engineering via continuous digital light processing
Virtual and Physical Prototyping, 2014Co-Authors: David Dean, Eric J Mott, Xinyi Luo, Mallory Busso, Martha O Wang, Charlotte E Vorwald, Ali Siblani, J FisherAbstract:The formulation of resorbable polymer Resins for light-based additive manufacturing of tissue engineered scaffolds goes beyond Resin Chemistry. There are at least four parameters that allow the transition from individual layer curing to 3D printing; they are: layer thickness, overcuring, step size, and inter-layer binding. Overcuring is the thickness of the layer minus step size. Overcuring distance limits surface feature resolution in the between-layer direction. Strength is an indication of crosslinking density and a function of inter-layer binding or ‘stitching’. 3D printed scaffolds must be sufficiently strong to endure cleaning of unpolymerised polymer from internal pore spaces without deforming. We report our study of the effect of exposure time on strength and layer thickness while holding step size constant. Increased overcuring dramatically increases scaffold strength. High resolution implants depend on sufficient energy from the light source and a well-tuned Resin consisting of: polymer, initiat...
Sharon M Hood - One of the best experts on this subject based on the ideXlab platform.
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growth and defense characteristics of whitebark pine pinus albicaulis and lodgepole pine pinus contorta var latifolia in a high elevation disturbance prone mixed conifer forest in northwestern montana usa
Forest Ecology and Management, 2021Co-Authors: Nickolas E Kichas, Sharon M Hood, Amy M Trowbridge, Kenneth F Raffa, Shealyn C Malone, Richard G Everett, David B Mcwethy, Gregory T PedersonAbstract:Abstract Recent, widespread tree mortality in the western U.S. resulting from changes in climate, pathogens, insect activity, and forest management practices has led to concerns for many ecologically and culturally important species. Within conifers, Resin-based defenses have long been recognized as a primary defense mechanism against a variety of insects and pathogens. OleoResin produced by trees contain complex mixtures of terpenoids that have numerous insecticidal and fungicidal properties. Research has also identified links between Resin duct characteristics and increased probability of survival during bark beetle outbreaks. Whitebark pine (Pinus albicaulis) is a culturally significant high elevation species that provides numerous ecological services within subalpine and alpine ecosystems. Whitebark pine has co-evolved with a suite of biotic and abiotic disturbances. Individual trees allocate resources towards growth and Resin-based defenses, making it a good candidate species to evaluate growth and defense relationships and tradeoffs. In this study we compared constitutive Resin Chemistry, tree growth and Resin duct anatomy between similarly aged whitebark and lodgepole pine (P. contorta var latifolia) growing in proximity within a disturbance-prone, mixed-conifer forest in northwestern Montana. These two host species have varying degrees of historical exposure to mountain pine beetle. Our research yields four important findings. First, we did not find evidence of a tradeoff between tree growth and tree defenses (Resin duct morphology and Resin Chemistry). This suggests that trees growing under favorable field conditions can experience high growth rates and still allocate ample resources towards defense. Second, we found that Resin ducts and constitutive mono- and sesqui- terpenes were not correlated in lodgepole pine while duct production and area were positively related to constitutive monoterpenes, and duct size and area were positively related to constitutive sesquiterpenes, in whitebark pine. The lack of distinct, consistent relationships between these defensive features suggests that both whitebark and lodgepole pine trees present beetles with numerous, complex combinations of Resin-based defenses. Third, based on constitutive terpene profiles, bark beetles are more likely to enter lodgepole pine but more likely to successfully elicit mass attacks in whitebark pine, which agrees with beetle attack and success patterns observed in the field. Fourth, overstory competition, particularly by Engelmann spruce (Picea engelmannii), can influence tree defenses, specifically by reducing constitutive terpene concentrations in lodgepole and whitebark pine. Competitive tree interactions could lead to altered bark beetle-conifer interactions as host and nonhost species migrate in response to changing climate. Our results suggest that strategies designed to support whitebark pine populations can benefit from better understanding interactions among growth, competition and physical and chemical defenses in response to multiple disturbance.
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fortifying the forest thinning and burning increase resistance to a bark beetle outbreak and promote forest resilience
Ecological Applications, 2016Co-Authors: Sharon M Hood, Stephen Baker, Anna SalaAbstract:Fire frequency in low-elevation coniferous forests in western North America has greatly declined since the late 1800s. In many areas, this has increased tree density and the proportion of shade-tolerant species, reduced resource availability, and increased forest susceptibility to forest insect pests and high-severity wildfire. In response, treatments are often implemented with the goal of increasing ecosystem resilience by increasing resistance to disturbance. We capitalized on an existing replicated study of fire and stand density treatments in a ponderosa pine (Pinus ponderosa)-Douglas-fir (Pseudotsuga menziesii) forest in western Montana, U.S. that experienced a naturally occurring mountain pine beetle (MPB; Dendroctonus ponderosae) outbreak five years after implementation of fuels treatments. We explored whether treatment effects on tree-level defense and stand structure affected resistance to MPB. Mortality from MPB was highest in the denser, untreated control and burn-only treatments, with approximately 50% and 39%, respectively, of ponderosa pine killed during the outbreak, compared to almost no mortality in the thin-only and thin-burn treatments. Thinning treatments, with or without fire, dramatically increased tree growth and Resin ducts relative to control and burn-only treatments. Prescribed burning did not increase Resin ducts, but did cause changes in Resin Chemistry that may have affected MPB communication and lowered attack success. While ponderosa pine remained dominant in the thin and thin-burn treatments after the outbreak, the high pine mortality in the control and burn-only treatment caused a shift in species dominance to Douglas-fir. The high Douglas-fir component in the control and burn-only treatments due to 20th century fire exclusion, coupled with high pine mortality from MPB, has likely reduced resilience of this forest beyond the ability to return to a ponderosa pine-dominated system in the absence of further fire or mechanical treatment. Our results show treatments designed to increase resistance to high-severity fire in ponderosa pine-dominated forests in the Northern Rockies can also increase resistance to MPB, even during an outbreak. This study suggests that fuel and restoration treatments in fire-dependent ponderosa pine forests that reduce tree density increase ecosystem resilience in the short term, while the reintroduction of fire is important for long-term resilience. This article is protected by copyright. All rights reserved.
Susila V Anand - One of the best experts on this subject based on the ideXlab platform.
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effect of Resin Chemistry on depth of cure and cytotoxicity of dental Resin composites
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2014Co-Authors: Susila V Anand, Venkatesh BalasubramanianAbstract:Abstract New dental composite restorative materials are being introduced aiming to overcome the disadvantages of contemporary materials. Hence there is a need to analyze the critical properties of these composites to aid in clinical application. This study aims to comparatively analyze the degree of conversion (DC), residual reactivity (DBC/reactivity) and cytotoxicity of 2 composites based on different Resin Chemistry. Ceram X and Filtek P90 were used in the study to prepare disc shaped samples of 2 mm thickness and 4 mm diameter. The samples for cytotoxicity were cured for 40 s and those of Fourier Transform Infra-red Spectroscopy (FTIR) (DBC/reactivity and DC) for 5 s, 10 s, 20 s and 40 s, at an average intensity of 800 mW/cm2 with Quartz–Tungsten–Halogen (QTH) light. DC was calculated in 60–100 μm thick and 6 mm diameter samples. Double bonds concentration/reactivity was measured in approximately 80 μm thick sections prepared from the 2 mm thick discs using a hard tissue microtome. The cell viability was scored by Trypan blue exclusion staining technique at 24 h and 48 h. Both composites showed a progressive increase in double bonds/reactivity as the distance from curing probe increased which was inversely proportional to the curing time. The DC of Filtek P90 was 20% and 96% and that of Ceram X 33% and 50% at 5 s and 40 s, respectively. Ceram X showed statistically significantly higher cell viability score at both 24 h and 48 h than Filtek P90. The results were statistically analyzed using non-parametric Kruskal–Wallis, Mann–Whitney U and Wilcoxon Signed Ranks tests. Though DC plays an important role in biocompatibility of dental composites, other factors like elution may play a significant role and hence need further evaluation.