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https://www.readbyqxmd.com/read/29241135/characterization-of-uranium-redox-state-in-organic-rich-eocene-sediments
#1
Susan A Cumberland, Barbara Etschmann, Joël Brugger, Grant Douglas, Katy Evans, Louise Fisher, Peter Kappen, John W Moreau
The presence of organic matter (OM) has a profound impact on uranium (U) redox cycling, either limiting or promoting the mobility of U via binding, reduction, or complexation. To understand the interactions between OM and U, we characterised U oxidation state and speciation in nine OM-rich sediment cores (18 samples), plus a lignite sample from the Mulga Rock polymetallic deposit in Western Australia. Uranium was unevenly dispersed within the analysed samples with 84% of the total U occurring in samples containing >21 wt % OM...
December 5, 2017: Chemosphere
https://www.readbyqxmd.com/read/29236329/predicting-the-bioavailability-of-sediment-bound-uranium-to-the-freshwater-midge-chironomus-dilutus-using-physicochemical-properties
#2
Sarah E Crawford, Stephen Lofts, Karsten Liber
Assessment of uranium (U)-contaminated sediment is often hindered by the inability to accurately account for the physicochemical properties of sediment that modify U bioavailability. The goal of this research was to determine whether sediment-associated U bioavailability could be predicted over a wide range of conditions and sediment properties using simple regressions and a geochemical speciation model, the Windermere Humic Aqueous Model (WHAM7). Data from U-contaminated field sediment bioaccumulation tests, along with previously published bioaccumulation studies with U-spiked field and formulated sediments were used to examine the models...
December 13, 2017: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/29230457/influence-of-macroscopic-defects-on-the-corrosion-behavior-of-u-0-79-wt-ti-alloy-in-sodium-chloride-solution
#3
Dingzhou Cai, Ming Wang, Yiming Ren, Shanli Yang, Ge Sang, Yingru Li
Uranium alloys containing a low concentration of titanium have received wide attention due to their greatly enhanced corrosion resistance and outstanding mechanical performances. Herein, we investigated the effect of macroscopic defects on the corrosion behavior of U-0.79 wt%Ti (denoted as U-Ti) alloy in 0.01 M NaCl solution using traditional electrochemical testing technologies and a novel scanning electrochemical composite probe (SECP). The results demonstrate that pitting corrosion occurs rapidly on the alloy surface due to macroscopic defects...
December 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29223802/proteogenomic-insights-into-uranium-tolerance-of-a-chernobyl-s-microbacterium-bacterial-isolate
#4
Gallois Nicolas, Alpha-Bazin Béatrice, Ortet Philippe, Barakat Mohamed, Piette Laurie, Long Justine, Berthomieu Catherine, Armengaud Jean, Chapon Virginie
Microbacterium oleivorans A9 is a uranium-tolerant actinobacteria isolated from the trench T22 located near the Chernobyl nuclear power plant. This site is contaminated with different radionuclides including uranium. To observe the molecular changes at the proteome level occurring in this strain upon uranyl exposure and understand molecular mechanisms explaining its uranium tolerance, we established its draft genome and used this raw information to perform an in-depth proteogenomics study. High-throughput proteomics were performed on cells exposed or not to 10μM uranyl nitrate sampled at three previously identified phases of uranyl tolerance...
December 6, 2017: Journal of Proteomics
https://www.readbyqxmd.com/read/29220714/mapping-of-radiation-anomalies-using-uav-mini-airborne-gamma-ray-spectrometry
#5
Ondřej Šálek, Milan Matolín, Lubomír Gryc
Localization of size-limited gamma-ray anomalies plays a fundamental role in uranium prospecting and environmental studies. Possibilities of a newly developed mini-airborne gamma-ray spectrometric equipment were tested on a uranium anomaly near the village of Třebsko, Czech Republic. The measurement equipment was based on a scintillation gamma-ray spectrometer specially developed for unmanned aerial vehicles (UAV) mounted on powerful hexacopter. The gamma-ray spectrometer has two 103 cm3 BGO scintillation detectors of relatively high sensitivity...
December 5, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29216427/a-novel-micro-emulsion-phase-transition-towards-the-elucidation-of-third-phase-formation-in-spent-nuclear-fuel-reprocessing
#6
Junju Mu, Ryuhei Motokawa, Kazuhiro Akutsu, Shotaro Nishitsuji, Andrew J Masters
We present evidence that the organic/third phase transition, as may be observed in the Plutonium Uranium Reduction EXtraction process (PUREX) at high metal loading, is an unusual transition between two isotropic, bi-continuous micro-emulsion phases. As this system contains so many components, however, we seek first to investigate the properties of a simpler system, viz. the related metal-free, quaternary system of water/n-dodecane/nitric acid/tri-butyl phosphate (TBP). Under appropriate conditions, this system exhibits three coexisting phases, namely the light organic phase, the third phase and the aqueous phase...
December 7, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29215327/factors-modifying-the-radon-related-lung-cancer-risk-at-low-exposures-and-exposure-rates-among-german-uranium-miners
#7
M Kreuzer, C Sobotzki, M Schnelzer, N Fenske
It is still not fully understood whether and how factors such as time, age and smoking modify the relationship between lung cancer and radon at low exposures and exposure rates. Improved knowledge is necessary for the dose conversion of radon in working level month (WLM) into effective dose, as currently discussed by the International Commission on Radiological Protection (ICRP). An update of the German uranium miner cohort study (n = 58,974 men) with a 10-year extension of mortality follow-up (1946-2013) was used to further examine this issue...
December 7, 2017: Radiation Research
https://www.readbyqxmd.com/read/29211078/a-hydrolytically-stable-uranyl-organic-framework-for-highly-sensitive-and-selective-detection-of-fe3-in-aqueous-media
#8
Wei Liu, Jian Xie, Linmeng Zhang, Mark A Silver, Shuao Wang
We present a depleted uranium-based metal organic framework, UO2(C8H3O6N)·DMF, that exhibits highly sensitive and selective detection towards Fe3+ ions in aqueous media with an extremely low detection limit of 6.3 ppb. This work offers insight into exploring the potential applications of actinide-based metal organic frameworks in the area of chemical sensing with intrinsic advantages of high selectivity and sensitivity.
December 6, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29202372/groundwater-chemistry-and-radon-222-distribution-in-jerba-island-tunisia
#9
Faten Telahigue, Belgacem Agoubi, Fayza Souid, Adel Kharroubi
The present study integrates hydrogeological, hydrochemical and radiogenic data of groundwater samples taken from the Plio-Quaternary unconfined aquifer of Jerba Island, southeastern Tunisia, in order to interpret the spatial variations of the groundwater quality and identify the main hydrogeochemical factors responsible for the high ion concentrations and radon-222 content in the groundwater analysed. Thirty-nine groundwater samples were collected from open wells widespread on the island. Physical parameters (EC, pH, TDS and T °) were measured, major ions (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, NO3- and HCO3-) were analysed and 222Rn concentrations were determined using a RAD7-H2O...
December 1, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29199369/hydraulic-connection-affects-uranium-distribution-in-the-gas-hure-salt-lake-qaidam-basin-china
#10
Jibin Han, Hongchen Jiang, Jianxin Xu, Syed Asim Hussain, Xiaolong Yuan, Xiwei Qin
The widespread hydraulic connection is necessary for the formation of a salt lake. However, only limited studies have ever been carried out to investigate the influence of the hydraulic connection on the distribution of elements around certain salt lake. In this study, a total of 66 water samples (including river water, stream water, spring water, brine, intercrystalline brine, well water, and drilling brine) were collected around the Gas Hure salt lake (GSKLH) to investigate the relationship between hydraulic connection and uranium (U) distribution via hydrochemistry and isotope (234U/238U, δ11B) techniques...
December 3, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29196691/evidence-for-single-metal-two-electron-oxidative-addition-and-reductive-elimination-at-uranium
#11
Benedict M Gardner, Christos E Kefalidis, Erli Lu, Dipti Patel, Eric J L McInnes, Floriana Tuna, Ashley J Wooles, Laurent Maron, Stephen T Liddle
Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition...
December 1, 2017: Nature Communications
https://www.readbyqxmd.com/read/29195123/uranium-vi-sorption-complexes-on-silica-in-the-presence-of-calcium-and-carbonate
#12
Alaaeldine Sh Saleh, Jun-Yeop Lee, Yongheum Jo, Jong-Il Yun
Uranium sorption on minerals and related solids depends to a large degree on its aqueous speciation. The present work attempts to understand the U(VI) sorption behavior on silica under environmentally relevant conditions, i.e. at neutral to weakly alkaline pH and in the presence of dissolved calcium and carbonate. Under these conditions, Ca(UO2)(CO3)32- and Ca2(UO2)(CO3)3(aq) complexes emerge as the dominant aqueous U(VI) species. The U(VI) sorption affinity was measured as a function of contact time, solution pH, and humic acid...
November 28, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29193373/solid-state-structure-of-tris-cyclopentadienide-uranium-iii-and-plutonium-iii
#13
Christos Apostolidis, Michal Dutkiewicz, Attila Kovacs, Olaf Walter
The organometallic tris-cyclopentadienide actinide(III) (AnCp₃) complexes have been reported first about 50 years ago. Up to now however only the NpCp₃ solid state structure has been studied. Here we report on the solid state structures of UCp₃ and PuCp₃ which are isostructural to their Np analogue. The structural models are supported by theoretical calculations and compared to their lanthanide analogues. The observed trends in changes of bond lengths might be indicator for an increased covalency in the bonding in the tris-cyclopentadienide actinide(iii) complexes (AnCp₃) compared to their lanthanide homologues...
November 28, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29191559/identifying-radon-priority-areas-and-dwellings-with-radon-exceedances-in-bulgaria-using-stored-cd-dvds
#14
D Pressyanov, I Dimitrova, K Mitev, S Georgiev, D Dimitrov
The implementation of the 2013/59/EURATOM directive in the part related to radon exposure imposes challenges for radon measurement methodology and radon survey design. Among them is the need to have estimates (preferably direct) of the annual average radon concentrations, which can be directly compared to the recommended reference levels. On this basis, the surveys should make possible the identification of dwellings with indoor radon above the reference levels and "radon priority areas" where significant proportion of the dwellings falls in this category...
November 27, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29182330/highly-efficient-interception-and-precipitation-of-uranium-vi-from-aqueous-solution-by-iron-electrocoagulation-combined-with-cooperative-chelation-by-organic-ligands
#15
Peng Li, Bao Zhun, Xuegang Wang, Ping Ping Liao, Guanghui Wang, Lizhang Wang, Yadan Guo, Weimin Zhang
A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0-18.52 μmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups, hydrophobically/hydrophiliclly would realize precuring of uranyl ion at pH<3.0, and a following iron-electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium (VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs...
November 28, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29177200/spatial-distribution-of-uranium-in-mice-kidneys-detected-by-laser-ablation-inductively-coupled-plasma-mass-spectrometry
#16
Venessa Jim, Corinne LaViolette, Margaret M Briehl, Jani C Ingram
The aim of the study is to better understand where uranium deposits in mice kidneys. The spatial distribution of uranium was examined in the kidneys of C57BL/6 mice using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Mice were exposed to varying levels of uranyl nitrate in their drinking water. Calibration standards were developed to allow for semi-quantitative measurement of uranium in the cortical and medullary regions of mice kidney by LA-ICP-MS. Scanning electron microscopy was used to image the ablation patterns on the kidney...
June 2017: Journal of Applied Bioanalysis
https://www.readbyqxmd.com/read/29167759/study-on-bioremediation-of-lead-by-exopolysaccharide-producing-metallophilic-bacterium-isolated-from-extreme-habitat
#17
Debajit Kalita, S R Joshi
Lead released from manufacturing factories, recycling plants, automobile company and landfill leachate is abundantly found in wastewater. An efficient bioremediating agent for lead removal from wastewater is expected to ease the ever increasing problem. The present study reports Pseudomonas sp. W6 isolated from extreme habitat of hot water spring of North-East India evaluated for its Lead biosorption property. The bacterium showed capacity to resist 1.0 mM lead in both solid and liquid minimal media. Epifluorescence microscopy reveal the viability of bacterial cells under metal stress condition...
December 2017: Biotechnology Reports
https://www.readbyqxmd.com/read/29167433/repeated-storage-of-respired-carbon-in-the-equatorial-pacific-ocean-over-the-last-three-glacial-cycles
#18
A W Jacobel, J F McManus, R F Anderson, G Winckler
As the largest reservoir of carbon exchanging with the atmosphere on glacial-interglacial timescales, the deep ocean has been implicated as the likely location of carbon sequestration during Pleistocene glaciations. Despite strong theoretical underpinning for this expectation, radiocarbon data on watermass ventilation ages conflict, and proxy interpretations disagree about the depth, origin and even existence of the respired carbon pool. Because any change in the storage of respiratory carbon is accompanied by corresponding changes in dissolved oxygen concentrations, proxy data reflecting oxygenation are valuable in addressing these apparent inconsistencies...
November 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/29165997/materials-for-the-recovery-of-uranium-from-seawater
#19
Carter W Abney, Richard T Mayes, Tomonori Saito, Sheng Dai
More than 1000× uranium exists in the oceans than exists in terrestrial ores. With nuclear power generation expected to increase over the coming decades, access to this unconventional reserve is a matter of energy security. With origins in the mid-1950s, materials have been developed for the selective recovery of seawater uranium for more than six decades, with a renewed interest in particular since 2010. This review comprehensively surveys materials developed from 2000-2016 for recovery of seawater uranium, in particular including recent developments in inorganic materials; polymer adsorbents and related research pertaining to amidoxime; and nanostructured materials such as metal-organic frameworks, porous-organic polymers, and mesoporous carbons...
November 22, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/29165807/arabidopsis-thaliana-plants-challenged-with-uranium-reveal-new-insights-into-iron-and-phosphate-homeostasis
#20
Serge Berthet, Florent Villiers, Claude Alban, Nelson B C Serre, Jacqueline Martin-Laffon, Sylvie Figuet, Anne-Marie Boisson, Richard Bligny, Marcel Kuntz, Giovanni Finazzi, Stéphane Ravanel, Jacques Bourguignon
Uranium (U) is a naturally occurring radionuclide that is toxic to plants. It is known to interfere with phosphate nutrition and to modify the expression of iron (Fe)-responsive genes. The transporters involved in the uptake of U from the environment are unknown. Here, we addressed whether IRT1, a high-affinity Fe(2+) transporter, could contribute to U uptake in Arabidopsis thaliana. An irt1 null mutant was grown hydroponically in different conditions of Fe bioavailability and phosphate supply, and challenged with uranyl...
November 22, 2017: New Phytologist
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