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1. Uranium mobility and accumulation along the Rio Paguate, Jackpile Mine in Laguna Pueblo, NM

   https://doi.org/10.1039/C6EM00612D  

   Blake, Johanna M.; De Vore, Cherie L.; Avasarala, Sumant; Ali, Abdul-Mehdi; Roldan, Claudia; Bowers, Fenton; Spilde, Michael N.; Artyushkova, Kateryna; Kirk, Matthew F.; Peterson, Eric; et al (January 2017, Environmental Science: Processes & Impacts)

   The mobility and accumulation of uranium (U) along the Rio Paguate, adjacent to the Jackpile Mine, in Laguna Pueblo, New Mexico was investigated using aqueous chemistry, electron microprobe, X-ray diffraction and spectroscopy analyses. Given that it is not common to identify elevated concentrations of U in surface water sources, the Rio Paguate is a unique site that concerns the Laguna Pueblo community. This study aims to better understand the solid chemistry of abandoned mine waste sediments from the Jackpile Mine and identify key hydrogeological and geochemical processes that affect the fate of U along the Rio Paguate. Solid analyses using X-ray fluorescence determined that sediments located in the Jackpile Mine contain ranges of 320 to 9200 mg kg −1 U. The presence of coffinite, a U( iv )-bearing mineral, was identified by X-ray diffraction analyses in abandoned mine waste solids exposed to several decades of weathering and oxidation. The dissolution of these U-bearing minerals from abandoned mine wastes could contribute to U mobility during rain events. The U concentration in surface waters sampled closest to mine wastes are highest during the southwestern monsoon season. Samples collected from September 2014 to August 2016 showed higher U concentrations in surface water adjacent to the Jackpile Mine (35.3 to 772 μg L −1 ) compared with those at a wetland 4.5 kilometers downstream of the mine (5.77 to 110 μg L −1 ). Sediments co-located in the stream bed and bank along the reach between the mine and wetland had low U concentrations (range 1–5 mg kg −1 ) compared to concentrations in wetland sediments with higher organic matter (14–15%) and U concentrations (2–21 mg kg −1 ). Approximately 10% of the total U in wetland sediments was amenable to complexation with 1 mM sodium bicarbonate in batch experiments; a decrease of U concentration in solution was observed over time in these experiments likely due to re-association with sediments in the reactor. The findings from this study provide new insights about how hydrologic events may affect the reactivity of U present in mine waste solids exposed to surface oxidizing conditions, and the influence of organic-rich sediments on U accumulation in the Rio Paguate. 

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2. Mapping the distribution of geogenic contaminants in bedrock from Colorado Plateau cores using continuous X-ray fluorescence spectroscopy

   Bebo, C; Tibbets, D; Chang; C; Pinella, M; Prabhakar, L (December 2023, Proceedings American Geophysical Union)

   OIsen, P (Ed.)

   The Navajo Nation is the largest Native American reservation in the United States and is located on the Colorado Plateau. Uranium (U) and Arsenic (As) are two predominantly geogenic contaminants found on the Colorado Plateau. These contaminants leech into groundwater aquifers through anthropogenic activities, but little information is known about the natural distribution of these contaminants. Heavy uranium and coal mining have caused elevated levels of U and As to infiltrate groundwater, however there is little research on the natural distribution of these elements in the regional bedrock and the extent to which they exist as exposure pathways in water, air, and soil. We used a robotic X-ray Fluorescence (XRF) machine, Minalyzer CS, to scan over 850 meters of cores that were collected in Petrified Forest National Park (PFNP) and generated a whole-rock geochemical profile with respect to depth and show the areas in the cores that have elevated levels of Uranium and Arsenic. We also sampled for Inductively Coupled Plasma Mass Spectrometry (ICPMS) to calibrate the concentrations of elements from our XRF scans. In conjunction with X-ray Diffraction (XRD) analysis to quantify mineralogy and Computed Tomography (CT) to quantify porosity/permeability, we are in the process of developing models for the integrated geologic history of the region and the processes responsible for the concentration and mobilization of these elements in bedrock. An understanding of these processes is essential for differentiating the exposure risk between geogenic and anthropogenic sources of U and As. 

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3. Room temperature synthesis of UO _2+x nanocrystals and thin films via hydrolysis of uranium( iv ) complexes

   https://doi.org/10.1039/D1QI01248G  

   Murillo, Jesse; Panda, Debiprasad; Chakrabarti, Subhananda; Hattori, Alex; Griego, Leonel; Chava, Venkata S.; Sreenivasan, Sreeprasad T.; Ramana, Chintalapalle V.; Fortier, Skye (January 2022, Inorganic Chemistry Frontiers)

   Methods for the straightforward, room temperature synthesis of UO 2+ x nanoparticles and thin films using solution processable, molecular uranium( iv ) compounds is described. Ultra-small uranium dioxide nanoparticles are synthesized from the hydrolysis of either U(ditox) 4 (ditox = − OCH t Bu 2 ) (1) or U(CH 2 SiMe 2 NSiMe 3 )[N(SiMe 3 ) 2 ] 2 (2) via addition of water to stirring solutions of the compounds in non-polar solvents to give UO 2 -1 and UO 2 -2, respectively. The structural characteristics of the uranium dioxide nanoparticles were characterized using powder X-ray diffraction (pXRD), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The pXRD results affirm the cubic fluorite structure expected for UO 2 nanoparticles. The nanocrystallinity of UO 2 -1 and UO 2 -2 were substantiated by bright-field HRTEM images and fast Fourier transform (FFT) patterns. The HRTEM analysis also shows the nanoparticles fall within the ultra-small regime possessing sizes of ∼3 nm with uniform distribution. Additionally, we demonstrate the versatility of 1 as a uranium dioxide precursor, showing that it can be readily sublimed onto glass or silicon substrates and subsequently hydrolyzed to give UO 2+ x thin films. 

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4. Comparing two extracellular additives to facilitate extended storage of red blood cells in a supercooled state

   https://doi.org/10.3389/fphys.2023.1165330  

   William, Nishaka; Isiksacan, Ziya; Mykhailova, Olga; Olafson, Carly; Yarmush, Martin L.; Usta, O. Berk; Acker, Jason P. (June 2023, Frontiers in Physiology)

   Background:Adenosine triphosphate (ATP) levels guide many aspects of the red blood cell (RBC) hypothermic storage lesions. As a result, efforts to improve the quality of hypothermic-stored red cell concentrates (RCCs) have largely centered around designing storage solutions to promote ATP retention. Considering reduced temperatures alone would diminish metabolism, and thereby enhance ATP retention, we evaluated: (a) whether the quality of stored blood is improved at −4°C relative to conventional 4°C storage, and (b) whether the addition of trehalose and PEG400 can enhance these improvements. Study Design and Methods:Ten CPD/SAGM leukoreduced RCCs were pooled, split, and resuspended in a next-generation storage solution (i.e., PAG3M) supplemented with 0–165 mM of trehalose or 0–165 mM of PEG400. In a separate subset of samples, mannitol was removed at equimolar concentrations to achieve a fixed osmolarity between the additive and non-additive groups. All samples were stored at both 4°C and −4°C under a layer of paraffin oil to prevent ice formation. Results:PEG400 reduced hemolysis and increased deformability in −4°C-stored samples when used at a concentration of 110 mM. Reduced temperatures did indeed enhance ATP retention; however, in the absence of an additive, the characteristic storage-dependent decline in deformability and increase in hemolysis was exacerbated. The addition of trehalose enhanced this decline in deformability and hemolysis at −4°C; although, this was marginally alleviated by the osmolarity-adjustments. In contrast, outcomes with PEG400 were worsened by these osmolarity adjustments, but at no concentration, in the absence of these adjustments, was damage greater than the control. Discussion:Supercooled temperatures can allow for improved ATP retention; however, this does not translate into improved storage success. Additional work is necessary to further elucidate the mechanism of injury that progresses at these temperatures such that storage solutions can be designed which allow RBCs to benefit from this diminished rate of metabolic deterioration. The present study suggests that PEG400 could be an ideal component in these solutions. 

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5. Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis

   https://doi.org/10.3389/fenvc.2023.1114807  

   Crowley, Brooke Erin; Bruff Simpson, Emily Michelle; Hammer, Sarah Jayne; Smith, Joshua Michael; Johnson, Thomas Martin (March 2023, Frontiers in Environmental Chemistry)

   Most researchers assume minimal impact of pretreatment on strontium isotope ratios ( 87 Sr/ 86 Sr) for bones and teeth, and methods vary tremendously. We compared 14 pretreatment methods, including no prep other than powdering enamel, ashing, soaking in water, an oxidizing agent (bleach or hydrogen peroxide) or acetic acid (0.1 M, 1.0 M, and 1.0 M buffered with calcium acetate), and a combination of these steps. We prepared and analyzed aliquots of powdered molar enamel from three proboscideans (one modern captive Indian elephant, Elephas maximus indicus ; one Pleistocene mastodon, Mammut americanum ; and one Miocene gomphothere, Afrochoerodon kisumuensis ). Each pretreatment was performed in triplicate and we measured 87 Sr/ 86 Sr, Sr concentration, and uranium (U) concentration, using the same lab space and instrumentation for all samples. Variability in 87 Sr/ 86 Sr and Sr and U concentrations was considerable across pretreatments. Mean 87 Sr/ 86 Sr across methods ranged from 0.70999 to 0.71029 for the modern tooth, 0.71458 to 0.71502 for the Pleistocene tooth, and 0.70804 to 0.70817 for the Miocene tooth. The modern tooth contained the least Sr and negligible U. The Pleistocene tooth contained slightly more Sr and measurable amounts of U, and the Miocene tooth had approximately 5x more Sr and U than the Pleistocene tooth. For all three teeth, variance in 87 Sr/ 86 Sr, Sr concentrations, and U concentrations among replicates was statistically indistinguishable across pretreatments, but there were apparent differences among pretreatments for the modern and Pleistocene teeth. Both contained relatively little Sr, and it is possible that small amounts of exogenous Sr from reagents, building materials or dust affected some replicates for some pretreatments. For the modern tooth, median 87 Sr/ 86 Sr varied considerably (but statistically insignificantly) across pretreatments. For the Pleistocene tooth, variability in median 87 Sr/ 86 Sr was also considerable; some pretreatments were statistically distinct but there were no obvious patterns among methods. For the Miocene tooth, variability in median 87 Sr/ 86 Sr was much smaller, but there were significant differences among pretreatments. Most pretreatments yielded 87 Sr/ 86 Sr and Sr concentrations comparable to, or lower than, untreated powder, suggesting selective removal of exogenous material with high 87 Sr/ 86 Sr. Further evaluation of the mechanisms driving isotopic variability both within and among pretreatment methods is warranted. Researchers should clearly report their methods and avoid combining data obtained using different methods. Small differences in 87 Sr/ 86 Sr could impact data interpretations, especially in areas where isotopic variability is low. 

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