Characterization of Dry-Air Aged Granules of Silver-Functionalized Silica Aerogel

This is a letter report to complete level 3 milestone "Assess aging characteristics of silica aerogels" for DOE FCRD program. Recently, samples of Ag0-functionalized silica aerogel were aged in flowing dry air for up to 6 months and then loaded with iodine. This dry-air aging simulated the impact of long-term exposure to process gases during process idling. The 6-month aged sample exhibited an iodine sorption capacity of 32 mass%, which was 9 mass % lower than that for an un-aged Ag0-functionalized silica aerogel. In an attempt to understand this decrease in sorption capacity, we characterized physical properties of the aged samples with Brunauer-Emmett-Teller (BET) nitrogen adsorption, X-ray diffraction (XRD), and high resolution scanning electron microscopy (SEM). The results showed no impact of aging on the aerogel microstructure or the silver nanoparticles in the aerogel, including their spatial distribution and morphology

The Nucleation and Growth of Calcium Oxalate Monohydrate on Self-Assembled Monolayers (SAMs)

A physical chemical approach was used to study calcium oxalate monohydrate (COM) nucleation and growth on various organic interfaces. Self-assembling monolayers (SAMs), containing derivatized organic functional groups, were designed to mimic various amino acid residues present in both urine and stone matrix macromolecules. Derivatized surfaces include SAMs with terminal methyl, bromo, imidazole, and thiazolidine-carboxylic acid functional groups. Pronounced differences in COM deposition were observed for the various interfaces with the imidazole and thiazolidine surfaces having the greatest effect and the methyl and bromo groups having little or no nucleating potential

Portable Analyzer Based on Microfluidics/Nanoengineered Electrochemical Sensors for In-situ Characterization of Mixed Wastes

Required characterizations of the DOE's transuranic (TRU) and mixed wastes (MW) before disposing and treatment of the wastes are currently costly and have lengthy turnaround. Research toward developing faster and more sensitive characterization and analysis tools to reduce costs and accelerate throughputs is therefore desirable. This project is aimed at the development of electrochemical sensors, specific to toxic transition metals, uranium, and technetium, that can be integrated into the portable sensor systems. This system development will include fabrication and performance evaluation of electrodes as well as understanding of electrochemically active sites on the electrodes specifically designed for toxic metals, uranium and technetium detection. Subsequently, these advanced measurement units will be incorporated into a microfluidic prototype specifically designed and fabricated for field-deployable characterizations of such species

Anthropogenic Disturbance and Population Viability of Woodland Caribou in Ontario

One of the most challenging tasks in wildlife conservation and management is to clarify how spatial variation in land cover due to anthropogenic disturbance influences wildlife demography and long‐term viability. To evaluate this, we compared rates of survival and population growth by woodland caribou (Rangifer tarandus caribou) from 2 study sites in northern Ontario, Canada that differed in the degree of anthropogenic disturbance because of commercial logging and road development, resulting in differences in predation risk due to gray wolves (Canis lupus). We used an individual‐based model for population viability analysis (PVA) that incorporated adaptive patterns of caribou movement in relation to predation risk and food availability to predict stochastic variation in rates of caribou survival. Field estimates of annual survival rates for adult female caribou in the unlogged ( x̄ = 0.90) and logged ( x̄ = 0.76) study sites recorded during 2010–2014 did not differ significantly (P \u3e 0.05) from values predicted by the individual‐based PVA model (unlogged:  x̄ = 0.87; logged:  x̄ = 0.79). Outcomes from the individual‐based PVA model and a simpler stage‐structured matrix model suggest that substantial differences in adult survival largely due to wolf predation are likely to lead to long‐term decline of woodland caribou in the commercially logged landscape, whereas the unlogged landscape should be considerably more capable of sustaining caribou. Estimates of population growth rates (λ) for the 2010–2014 period differed little between the matrix model and the individual‐based PVA model for the unlogged (matrix model  x̄ = 1.01; individual‐based model x̄ = 0.98) and logged landscape (matrix model x̄ = 0.88; individual‐based model x̄ = 0.89). We applied the spatially explicit PVA model to assess the viability of woodland caribou across 14 woodland caribou ranges in Ontario. Outcomes of these simulations suggest that woodland caribou ranges that have experienced significant levels of commercial forestry activities in the past had annual growth rates 0.96. These differences were strongly related to regional variation in wolf densities. Our results suggest that increased wolf predation risk due to anthropogenic disturbance is of sufficient magnitude to cause appreciable risk of population decline in woodland caribou in Ontario. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society

Landscape-Level Wolf Space Use is Correlated With Prey Abundance, Ease of Mobility and the Distribution of Prey Habitat

Predator space use influences ecosystem dynamics, and a fundamental goal assumed for a foraging predator is to maximize encounter rate with prey. This can be achieved by disproportionately utilizing areas of high prey density or, where prey are mobile and therefore spatially unpredictable, utilizing patches of their prey\u27s preferred resources. A third, potentially complementary strategy is to increase mobility by using linear features like roads and/or frozen waterways. Here, we used novel population-level predator utilization distributions (termed localized density distributions ) in a single-predator (Wolf), two-prey (moose and caribou) system to evaluate these space-use hypotheses. The study was conducted in contrasting sections of a large boreal forest area in northern Ontario, Canada, with a spatial gradient of human disturbances and predator and prey densities. Our results indicated that wolves consistently used forest stands preferred by moose, their main prey species in this part of Ontario. Direct use of prey-rich areas was also significant but restricted to where there was a high local density of moose, whereas use of linear features was pronounced where local moose density was lower. These behaviors suggest that Wolf foraging decisions, while consistently influenced by spatially anchored patches of prey forage resources, were also determined by local ecological conditions, specifically prey density. Wolves appeared to utilize prey-rich areas when regional preferred prey density exceeded a threshold that made this profitable, whereas they disproportionately used linear features that promoted mobility when low prey density made directly tracking prey distribution unprofitable

Selection for Forage and Avoidance of Risk by Woodland Caribou (Rangifer Tarandus Caribou) at Coarse andLocal Scales

The relationship between selection at coarse and fine spatiotemporal spatial scales is still poorly understood. Some authors claim that, to accommodate different needs at different scales, individuals should have contrasting selection patterns at different scales of selection, while others claim that coarse scale selection patterns should reflect fine scale selection decisions. Here we examine site selection by 110 woodland caribou equipped with GPS radio‐collars with respect to forage availability and predation risk across a broad gradient in availability of both variables in boreal forests of Northern Ontario. We tested whether caribou selection for forage and avoidance of risk was consistent between coarse (seasonal home range) and fine scales of selection. We found that local selection patterns predicted coarse scale selection patterns, indicating a close relationship between the drivers of selection at both spatial scales

ACTINIDE-SPECIFIC INTERFACIAL CHEMISTRY OF MONOLAYER COATED MESOPOROUS CERAMICS

The objective of this program was to design, synthesize, and evaluate high-efficiency, high-capacity sorbent materials capable of selectively sequestering actinides and other radionuclides from complex aqueous mixtures. One of the central goals of this project was to understand the fundamental interfacial science required to develop novel mesoporous materials coated with organized monolayers of rationally designed ligands, custom-tailored for binding specific actinide cations. This capability addresses waste management by separation of actinides, a central concern of high-level waste (HLW) management at several DOE sites

Environmental Application of Nanomaterials

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Actinide-Specific Interfacial Chemistry of Monolayer Coated Mesoporous Ceramics

The objective of this program is to design, synthesize, and evaluate high-efficiency, high-capacity sorbent materials capable of selectively sequestering actinides from complex aqueous mixtures. One of the central goals of this project is to understand the fundamental interfacial science required to develop novel mesoporous materials coated with organized monolayers of rationally designed ligands, custom-tailored for binding specific actinide cations. This capability addresses waste management by separation of actinides, a central concern of high-level waste (HLW) management at several DOE sites. PNNL has developed self-assembled monolayers on mesoporous supports (SAMMS) as a superior method of mercury and heavy metal sequestration. SAMMS has proven to be orders of magnitude faster and more effective than existing mercury-scavenging methods. This project builds on the SAMMS concept and extends the interfacial chemistry of monolayer-coated mesoporous materials to study the requirements of selective binding of actinides. The need exists in the management of DOE's HLW to be able to selectively and completely remove the actinides so that HLW volume can be minimized and the nonradioactive components can be segregated and disposed of as low-level waste (LLW). In addition, the short-term risk assessment for tank closure requires a complete and accurate accounting of actinide speciation. These needs dictate the development of selective and efficient separation of actinides from complex waste streams so as to minimize HLW volume, reduce waste management costs, and enhance long-term stability of the HLW form