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https://www.readbyqxmd.com/read/29455528/uranyl-to-uranium-iv-conversion-through-manipulation-of-axial-and-equatorial-ligands
#1
Nicola L Bell, Brian Shaw, Polly L Arnold, Jason B Love
The controlled manipulation of the axial oxo and equatorial halide ligands in the uranyl dipyrrin complex, UO2Cl(L) allows the uranyl reduction potential to be shifted by 1.53 V into the range accessible to naturally occurring reductants that are present during uranium remediation and storage processes. Abstraction of the equatorial halide ligand to form the uranyl cation causes a 780 mV positive shift in the UV/UIV reduction potential. Borane-functionalization of the axial oxo groups causes the spontaneous homolysis of the equatorial U-Cl bond and a further 750 mV shift of this potential...
February 18, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29453264/bacterial-community-shift-and-coexisting-coexcluding-patterns-revealed-by-network-analysis-in-a-bioreduced-uranium-contaminated-site-after-reoxidation
#2
Bing Li, Wei-Min Wu, David B Watson, Erick Cardenas, Yuanqing Chao, D H Phillips, Tonia Mehlhorn, Kenneth Lowe, Shelly D Kelly, Pengsong Li, Huchun Tao, James M Tiedje, Craig S Criddle, Tong Zhang
A site in Oak Ridge, Tennessee, USA, has sediments that contain >3% iron oxides and is contaminated with uranium (U). The U(VI) was bioreduced to U(IV) and immobilized in situ through intermittent injections of ethanol. Then it was allowed to reoxidize via the invasion of low-pH (3.6-4.0), high-nitrate (up to 200 mM) groundwater back into the reduced zone for 1,383 days. To examine the biogeochemical response, high-throughput sequencing and network analysis were applied to characterize bacterial population shifts, as well as co-occurrence and co-exclusion patterns among microbial communities...
February 16, 2018: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29453061/effect-of-u-vi-aqueous-speciation-on-the-binding-of-uranium-by-the-cell-surface-of-rhodotorula-mucilaginosa-a-natural-yeast-isolate-from-bentonites
#3
Margarita Lopez-Fernandez, Maria Romero-González, Alix Günther, Pier L Solari, Mohamed L Merroun
This study presents the effect of aqueous uranium speciation (U-hydroxides and U-hydroxo-carbonates) on the interaction of this radionuclide with the cells of the yeast Rhodotorula mucigilanosa BII-R8. This strain was isolated from Spanish bentonites considered as reference materials for the engineered barrier components of the future deep geological repository of radioactive waste. X-ray absorption and infrared spectroscopy showed that the aqueous uranium speciation has no effect on the uranium binding process by this yeast strain...
February 9, 2018: Chemosphere
https://www.readbyqxmd.com/read/29453051/hno-3-modified-biochars-for-uranium-vi-removal-from-aqueous-solution
#4
Jie Jin, Shiwei Li, Xianqiang Peng, Wei Liu, Chenlu Zhang, Yan Yang, Lanfang Han, Ziwen Du, Ke Sun, Xiangke Wang
The HNO 3 treatment was used to chemically modify the biochars produced from wheat straw (WH) and cow manure for U(VI) removal from aqueous solution. Macroscopic experiments proved that the enrichment of U(VI) on the biochars was regulated by surface complexation and electrostatic interactions. FTIR and XPS analyses confirmed that the highly efficient adsorption of U(VI) was due to the carboxyl groups on the biochar surfaces. The reducing agents of the R-CH 2 OH groups facilitated U(VI) adsorption on the untreated biochars...
February 7, 2018: Bioresource Technology
https://www.readbyqxmd.com/read/29450422/remarkable-structural-effects-on-the-complexation-of-actinides-with-h-phosphonates-a-combined-experimental-and-quantum-chemical-study
#5
Aditi Chandrasekar, Brahmmananda Rao C V S, Mahesh Sundararajan, Tapan K Ghanty, N Sivaraman
The structural effects of the carbon chain on the extraction of actinides by organo-phosphorus extractants have been examined experimentally and by computation. Branched butyl H-phosphonates and their linear chain isomer, n-butyl H-phosphonate (DBHP), were synthesised and characterised using IR, NMR and GC-MS techniques. Their physical properties viz. viscosity, density and aqueous solubility have been examined. DBHP, Di-iso-butyl H phosphonate (DiBHP) and Di-sec-butyl H phosphonate (DsBHP) were employed for the extraction of uranium and americium ions from nitric acid...
February 16, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29448175/metals-in-mangrove-ecosystems-and-associated-biota-a-global-perspective
#6
REVIEW
Rasika Kulkarni, Deepti Deobagkar, Smita Zinjarde
Mangrove forests prevalent along the intertidal regions of tropical and sub-tropical coastlines are inimitable and dynamic ecosystems. They protect and stabilize coastal areas from deleterious consequences of natural disasters such as hurricanes and tsunamis. Although there are reviews on ecological aspects, industrial uses of mangrove-associated microorganisms and occurrence of pollutants in a region-specific manner, there is no exclusive review detailing the incidence of metals in mangrove sediments and associated biota in these ecosystems on a global level...
February 12, 2018: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/29448060/a-rapid-method-for-the-sequential-separation-of-polonium-plutonium-americium-and-uranium-in-drinking-water
#7
B Lemons, H Khaing, A Ward, P Thakur
A new sequential separation method for the determination of polonium and actinides (Pu, Am and U) in drinking water samples has been developed that can be used for emergency response or routine water analyses. For the first time, the application of TEVA chromatography column in the sequential separation of polonium and plutonium has been studied. This method utilizes a rapid Fe +3 co-precipitation step to remove matrix interferences, followed by plutonium oxidation state adjustment to Pu 4+ and an incubation period of ~ 1 h at 50-60 °C to allow Po 2+ to oxidize to Po 4+ ...
February 6, 2018: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29443101/methods-for-analyzing-the-impacts-of-natural-uranium-on-in-vitro-osteoclastogenesis
#8
Tatiana Gritsaenko, Valérie Pierrefite-Carle, Gaëlle Creff, Claude Vidaud, Georges Carle, Sabine Santucci-Darmanin
Uranium has been shown to interfere with bone physiology and it is well established that this metal accumulates in bone. However, little is known about the effect of natural uranium on the behavior of bone cells. In particular, the impact of uranium on osteoclasts, the cells responsible for the resorption of the bone matrix, is not documented. To investigate this issue, we have established a new protocol using uranyl acetate as a source of natural uranium and the murine RAW 264.7 cell line as a model of osteoclast precursors...
January 30, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29443009/radon-in-brazilian-underground-mines
#9
Anna Luiza Marques Ayres da Silva, Sérgio Médici Eston, Wilson Siguemasa Iramina, Diego Diegues Francisca
Radon is a chemically inert noble radioactive gas found in several radioactive decay chains. In underground mines, especially those that contain or have contained ores associated with uranium-bearing minerals, workers might be exposed to high levels of radon and its decay products (RDP). This work aimed to investigate whether the exposure of workers to radon gas and its progeny has been evaluated in Brazilian non-uranium and non-thorium underground mines. If so, the results and control measures undertaken or recommended to maintain the concentrations under Brazilian occupational exposure limits (OELs) were documented...
February 14, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29433000/unrefined-humic-substances-as-a-potential-low-cost-amendment-for-the-management-of-acidic-groundwater-contamination
#10
Hansell Gonzalez-Raymat, Vasileios Anagnostopoulos, Miles Denham, Yong Cai, Yelena P Katsenovich
The present study explores a novel application of Huma-K, a commercially available, unrefined humic substance, as a promising low-cost source of organic matter for in situ remediation of contaminated acidic groundwater plumes. This can be achieved by creating a humic-rich coating on the surface of minerals which can enhance the sorption of contaminants from groundwater. Huma-K was characterized by means of scanning electron microscopy equipped with energy dispersive spectroscopy, Fourier-transform infrared analysis, and potentiometric titrations...
February 9, 2018: Journal of Environmental Management
https://www.readbyqxmd.com/read/29431434/unexpected-magnetic-ordering-on-the-cr-substructure-in-ucr2si2c-and-structural-relationships-in-quaternary-u-cr-si-c-compounds
#11
Pierric Lemoine, Anne Vernière, Mathieu Pasturel, Gérard Venturini, Bernard Malaman
Previous experimental and theoretical studies revealed that carbon insertion into the RCr2Si2 compounds drastically affects the magnetic behavior, since chromium does not carry any magnetic moment in RCr2Si2C (R = Y, La-Sm, Gd-Er) compounds in contrast to RCr2Si2 (R = Y, Sm, Gd-Lu, Th) compounds. In this study, we report on the unexpected magnetic ordering of chromium atoms in the isotype quaternary UCr2Si2C compound. While specific heat and magnetic measurements suggest a Pauli paramagnetic behavior, neutron powder diffraction reveals an antiferromagnetic ordering of the chromium substructure at high temperature (TN > 300 K), while that of uranium remains nonmagnetically ordered down to 2 K...
February 12, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29428857/microbial-communities-associated-with-uranium-in-situ-recovery-mining-process-are-related-to-acid-mine-drainage-assemblages
#12
Thomas Coral, Michaël Descostes, Hélène De Boissezon, Rizlan Bernier-Latmani, Luiz Felippe de Alencastro, Pierre Rossi
A large fraction (47%) of the world's uranium is mined by a technique called "In Situ Recovery" (ISR). This mining technique involves the injection of a leaching fluid (acidic or alkaline) into a uranium-bearing aquifer and the pumping of the resulting solution through cation exchange columns for the recovery of dissolved uranium. The present study reports the in-depth alterations brought to autochthonous microbial communities during acidic ISR activities. Water samples were collected from a uranium roll-front deposit that is part of an ISR mine in operation (Tortkuduk, Kazakhstan)...
February 8, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29425915/toxicokinetic-and-toxicodynamic-of-depleted-uranium-in-the-zebrafish-danio-rerio
#13
Olivier Simon, Béatrice Gagnaire, Virginie Camilleri, Isabelle Cavalié, Magali Floriani, Christelle Adam-Guillermin
This study investigated the accumulation pattern and biological effects (genotoxicity and histopathology) to adult zebrafish (male and female) exposed to a nominal waterborne concentration of 20 μg L-1 of depleted uranium (DU) for 28 days followed by 27 days of depuration. Accumulation pattern showed that (i) DU accumulated in brain, (ii) levels in digestive tract were higher than those measured in gills and (iii) levels remained high in kidney, brain and ovary despite the 27 days of depuration period...
December 30, 2017: Aquatic Toxicology
https://www.readbyqxmd.com/read/29425784/the-reach-of-human-health-risks-associated-with-metals-metalloids-in-water-and-vegetables-along-a-contaminated-river-catchment-south-africa-and-mozambique
#14
Bettina Genthe, Thandi Kapwata, Wouter Le Roux, Jessica Chamier, Caradee Y Wright
BACKGROUND: Anthropogenic pollution was identified as an environmental problem of concern when, in 2008, dozens of crocodiles died in the Olifants River catchment near the border of South Africa and Mozambique. Given the close proximity of households to the river and their making use of river water, we aimed to determine to what extent water pollution has an impact on health of indigent communities in South Africa and Mozambique in the catchment area. METHODS: Water and vegetable samples were collected from the study areas...
February 1, 2018: Chemosphere
https://www.readbyqxmd.com/read/29424357/action-levels-for-airborne-uranium-in-the-workplace-chemical-and-radiological-assessments
#15
Richard Wayne Leggett, Robert Meck
A method is described for deriving two levels of action, an investigation level (IL) and an immediate action level (IAL), for different forms and mixtures of the natural uranium (U) isotopes 234U, 235U, and 238U in air in the workplace. An IL indicates the need to confirm the validity of moderately elevated measurements of airborne U and adequacy of confinement controls and determine whether work limitations are appropriate. An IAL indicates that safeguards should be put into place immediately, including removal of workers from further exposure until conditions are acceptable...
February 9, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/29424024/impulse-oscillometry-measurement-of-distal-airways-obstruction-in-depleted-uranium-exposed-gulf-war-veterans
#16
Stella E Hines, Ashley H Barnes, Clayton Brown, Patricia Gucer, Marc S Oliver, Joanna M Gaitens, Marian Condon, Melissa McDiarmid
INTRODUCTION: A cohort of Gulf War I veterans who sustained exposure to depleted uranium undergoes biennial surveillance for potential uranium-related health effects. We performed impulse oscillometry and hypothesized that veterans with higher uranium body burdens would have more obstructive abnormalities than those with lower burdens. METHODS: We compared pulmonary function of veterans in high versus low urine uranium groups by evaluating spirometry and oscillometry values...
February 9, 2018: American Journal of Industrial Medicine
https://www.readbyqxmd.com/read/29423920/molecularly-imprinted-porous-aromatic-frameworks-and-their-composite-components-for-selective-extraction-of-uranium-ions
#17
Ye Yuan, Yajie Yang, Xujiao Ma, Qinghao Meng, Lili Wang, Shuai Zhao, Guangshan Zhu
Selective extraction of uranium from water has attracted worldwide attention because the largest source of uranium is seawater with various interference ions (Na+ , K+ , Mg2+ , Ca2+ , etc.). However, traditional adsorbents encapsulate most of their functional sites in their dense structure, leading to problems with low selectivity and adsorption capacities. In this work, the tailor-made binding sites are first decorated into porous skeletons, and a series of molecularly imprinted porous aromatic frameworks are prepared for uranium extraction...
February 9, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29421755/validation-of-the-bcr-sequential-extraction-procedure-for-natural-radionuclides
#18
S M Pérez-Moreno, M J Gázquez, R Pérez-López, J P Bolivar
Determining the availability of natural radionuclides in environmental conditions is increasingly important in order to evaluate their toxicity. A validated procedure is necessary to ensure the comparability and accuracy of the results obtained by different laboratories. For that, an optimised BCR sequential extraction procedure has been applied to the certified reference material (CRM), coded as BCR-701, and their resulting liquid and solid fractions were subjected to an exhaustive chemical and radioactivity characterisation...
February 1, 2018: Chemosphere
https://www.readbyqxmd.com/read/29419291/tailoring-the-electronic-structure-of-uranium-mono-imido-species-through-ligand-variation
#19
John J Kiernicki, Caleb J Tatebe, Matthias Zeller, Suzanne C Bart
Uranium mono(imido) species have been prepared via the oxidation of Cp*U( Mes PDI Me )(THF) (1-Cp*) and [Cp P U( Mes PDI Me )] 2 (1-Cp P ), where Cp* = η 5 -1,2,3,4,5-pentamethylcyclopentadienide, Cp P = 1-(7,7-dimethylbenzyl)cyclopentadienide, Mes PDI Me = 2,6-[(Mes)N═CMe] 2 C 5 H 3 N, and Mes = 2,4,6-trimethylphenyl, with organoazides. Treating either with N 3 DIPP (DIPP = 2,6-diisopropylphenyl) formed uranium(IV) mono(imido) complexes, Cp P U(NDIPP)( Mes PDI Me ) (2-Cp P ) and Cp*U(NDIPP)( Mes PDI Me ) (2-Cp*), featuring reduced [ Mes PDI Me ] - ...
February 8, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29417188/assessment-of-bacterial-community-composition-of-anaerobic-granular-sludge-in-response-to-short-term-uranium-exposure
#20
Taotao Zeng, Shiqi Zhang, Xiang Gao, Guohua Wang, Piet N L Lens, Shuibo Xie
The effect of 10-50 μM uranium (U(VI)) on the bacterial community of anaerobic granular sludge was investigated by 24-h exposure tests, after which the bacterial community was analyzed by high-throughput sequencing. The specific U(VI) reducing activity of the anaerobic granular sludge ranged between 3.1 to 19.7 μM U(VI) g-1(VSS) h-1, independently of the initial U(VI) concentration. Alpha diversity revealed that microbial richness and diversity was the highest for anaerobic granular sludge upon 10 μM uranium exposure...
February 7, 2018: Microbial Ecology
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