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Alison B Altman, Alexandra C Brown, Guodong Rao, Trevor D Lohrey, R David Britt, Laurent Maron, Stefan G Minasian, David K Shuh, John Arnold
Thorium sits at a unique position on the periodic table. On one hand, there is little evidence that its 5f orbitals engage in bonding as they do in other early actinides; on the other hand, its chemistry is distinct from Lewis acidic transition metals. To gain insight into the underlying electronic structure of Th and develop trends across the actinide series, it is useful to study Th(iii) and Th(ii) systems with valence electrons that may engage in non-electrostatic metal-ligand interactions, although only a handful of such systems are known...
May 14, 2018: Chemical Science
Haijian Li, Philip Kegler, Vladislav V Klepov, Martina Klinkenberg, Dirk Bosbach, Evgeny V Alekseev
Two uranium and two thorium silicates were obtained using high temperature mixed fluxes methods. K14 (UO2 )3 Si10 O30 crystallizes in the P21 / c space group and contains open-branched sechser (six) single silicate chains, whereas K2 (UO2 )Si2 O6 crystallizes in the C2/ c space group and is built of unbranched achter (eight) silicate chains. The crystals of K14 (UO2 )3 Si10 O30 and K2 (UO2 )Si2 O6 are related by increasing U/Si molar ratios, and both structures contain the same secondary building units (SBUs), [USi6 ] heptamers...
May 16, 2018: Inorganic Chemistry
Hugh W Ducklow, Michael R Stukel, Rachel Eveleth, Scott C Doney, Tim Jickells, Oscar Schofield, Alex R Baker, John Brindle, Rosie Chance, Nicolas Cassar
New production (New P, the rate of net primary production (NPP) supported by exogenously supplied limiting nutrients) and net community production (NCP, gross primary production not consumed by community respiration) are closely related but mechanistically distinct processes. They set the carbon balance in the upper ocean and define an upper limit for export from the system. The relationships, relative magnitudes and variability of New P (from 15 NO3 - uptake), O2  : argon-based NCP and sinking particle export (based on the 238 U : 234 Th disequilibrium) are increasingly well documented but still not clearly understood...
June 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Tara Mastren, Benjamin W Stein, T Gannon Parker, Valery Radchenko, Roy Copping, Allison Owens, Lance E Wyant, Mark Brugh, Stosh A Kozimor, F Meiring Nortier, Eva R Birnbaum, Kevin D John, Michael Ernst-Heinrich Fassbender
Protactinium-230 (t1/2 17.4 d) is the parent isotope of 230U (t1/2 20.8 d), a radionuclide of interest for targeted alpha therapy (TAT). Column chromatographic methods have been developed to separate no-carrier-added 230Pa from proton irradiated thorium targets and accompanying fission products. Results reported within demonstrate the use of novel sulfur bearing chromatographic extraction resins for the selective separation of protactinium. The recovery yield of 230Pa was 93 ± 4 % employing a R3P=S type commercially available resin and 88 ± 4 % employing a DGTA (diglycothioamide) containing custom synthesized extraction chromatographic resin...
May 14, 2018: Analytical Chemistry
Nicholas S Settineri, John Arnold
The reactivity of the thorium monoalkyl complex Th(CH2 SiMe3 )(BIMA)3 [ 1 , BIMA = MeC(Ni Pr)2 ] with various small molecules is described. While steric congestion prohibits the insertion of N , N '-diisopropylcarbodiimide into the Th-C bond in 1 , the first thorium tetrakis(amidinate) complex, Th(BIMA)4 ( 2 ), is synthesized via an alternative salt metathesis route. Insertion of p -tolyl azide leads to the triazenido complex Th[( p -tolyl)NNN(CH2 SiMe3 )-κ2 N1,2 ](BIMA)3 ( 3 ), which then undergoes thermal decomposition to the amido species Th[( p -tolyl)N(SiMe3 )](BIMA)3 ( 4 )...
March 14, 2018: Chemical Science
Marcilei A Guazzelli da Silveira, Bruno Ribeiro Pereira, Nilberto H Medina, Marcia A Rizzutto
This study reports the results obtained in the analysis of waste material samples generated by the industries of phosphate fertilizers, in particular, the use of specific filters in a portable X-ray fluorescence system, a simple equipment allowing the characterization, identification and quantification of low concentrations of Th and U (ppm). The industrial byproduct is classified as a Technologically-Enhanced, Naturally-Occurring Radioactive Material - TENORM, and therefore requires monitoring for its radio-toxic activity due to the presence of radioactive thorium and uranium families...
April 28, 2018: Journal of Environmental Radioactivity
Gaoxue Wang, Enrique R Batista, Ping Yang
Nanocrystals (NCs) with size and shape dependent properties are a thriving research field. Remarkable progress has been made in the controlled synthesis of NCs of stable elements in the past two decades; however, the knowledge of the NCs of actinide compounds has been considerably limited due the difficulties in handling them both experimentally and theoretically. Actinide compounds, especially actinide oxides, play a critical role in many stages of the nuclear fuel cycle. Recently, a non-aqueous surfactant assisted approach has been developed for the synthesis of actinide oxide NCs with different morphologies, but an understanding of its control factors is still missing to date...
April 27, 2018: Physical Chemistry Chemical Physics: PCCP
Zewei Jiang, Ekaterina Revskaya, Darrell R Fisher, Ekaterina Dadachova
OBJECTIVE: The demand for the alpha-emitting radionuclide Actinium-225 (225Ac) for use in radionuclide therapy is growing. Producing 225Ac using high energy linear accelerators, cyclotrons or photoinduction could increase its supply. One potential problem with accelerator produced 225Ac using Thorium-232 targets is the presence in final product of 0.1-0.3% by activity of the long-lived 227Ac impurity at the end of irradiation. It is important to comprehensively evaluate the behavior of accelerator-produced 225Ac in vivo before using it in pre-clinical and clinical applications...
April 23, 2018: Current Radiopharmaceuticals
Santiago Hurtado-Bermúdez, María Villa-Alfageme, José Luis Mas, María Dolores Alba
The development of Deep Geological Repositories (DGP) to the storage of high-level radioactive waste (HLRW) is mainly focused in systems of multiple barriers based on the use of clays, and particularly bentonites, as natural and engineered barriers in nuclear waste isolation due to their remarkable properties. Due to the fact that uranium is the major component of HLRW, it is required to go in depth in the analysis of the chemistry of the reaction of this element within bentonites. The determination of uranium under the conditions of HLRW, including the analysis of silicate matrices before and after the uranium-bentonite reaction, was investigated...
April 5, 2018: Applied Radiation and Isotopes
Golbarg M Roozbahani, Xiaohan Chen, Youwen Zhang, Oscar Juarez, Dien Li, Xiyun Guan
Thorium is a well-known radioactive and chemically toxic contaminant in the environment. The continuous exposure to thorium may cause an increased risk of developing lung and liver diseases as well as lung, pancreas and bone cancer. Due to its use in nuclear industry and other industrial applications, thorium may be accidentally released to the environment from its mining and processing plants. In this work, we developed a rapid, real-time, and label-free nanopore sensor for Th4+ detection by using an aspartic acid-containing peptide as a chelating agent and tuning the electrolyte solution pH to control the net charges of the peptide ligand and its metal ion complex...
April 12, 2018: Analytical Chemistry
Yanlong Wang, Wei Liu, Zhuanling Bai, Tao Zheng, Mark A Silver, Yuxiang Li, Yaxing Wang, Xia Wang, Juan Diwu, Zhifang Chai, Shuao Wang
Actinide based metal-organic frameworks (MOFs) are unique not only because compared to the transition metal and lanthanide systems, they are substantially less explored, but also owing to the uniqueness of actinide ions in bonding and coordination. We report here a new 3D thorium-organic framework (SCU-11) that contains a series of cages with an effective size of ca. 21  24 Å. Th4+ in SCU-11 is 10-coordinate with a new bicapped square prism coordination geometry, which has never been documented for any metal cation complexes before...
March 30, 2018: Angewandte Chemie
Mohamed M Rezk
The adult male albino rats were grouped into five groups (control group and four variably treated groups with thorium (Th) in single or successive with or without alginate treatment). The IP administration of thorium nitrate (13.6 mg/kg b.wt.) induced a regional distribution and accumulation ordered as cerebellum > cerebral cortex > brain stem > hippocampus > hypothalamus > striatum. Also, it induces a significant increase in Na+ , Ca2+ , and Fe3+ ion content and malondialdehyde (MDA) level while K+ ions and glutathione (GSH) level were significantly decreased...
March 29, 2018: Biological Trace Element Research
Nicholas R Andreychuk, Tara Dickie, David J H Emslie, Hilary A Jenkins
Palladium-catalyzed coupling of 1-adamantylamine (2 equiv.) with 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethylxanthene afforded the proligand 4,5-bis(1-adamantylamino)-2,7-di-tert-butyl-9,9-dimethylxanthene, H2[XAd] (1), which upon deprotonation with excess KH or KCH2Ph in THF or dme generated [{K(THF)3}2(XAd)] (2a) and [K2(XAd)(dme)] (2b). Subsequent reaction of in situ generated 2a or 2b with [ThCl4(dme)2] yielded [(XAd)ThCl4K2]·x(dme) (3; x = 0.5-2), which reacted with 2 equiv. of LiCH2SiMe3 or K[allylTMS] to afford the bis(hydrocarbyl) complexes [(XAd)Th(CH2SiMe3)2(THF)] (4) and [(XAd)Th(η3-allylTMS)2] {5; allylTMS = 1-(SiMe3)C3H4}...
April 3, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
F Nestola, N Korolev, M Kopylova, N Rotiroti, D G Pearson, M G Pamato, M Alvaro, L Peruzzo, J J Gurney, A E Moore, J Davidson
Laboratory experiments and seismology data have created a clear theoretical picture of the most abundant minerals that comprise the deeper parts of the Earth's mantle. Discoveries of some of these minerals in 'super-deep' diamonds-formed between two hundred and about one thousand kilometres into the lower mantle-have confirmed part of this picture. A notable exception is the high-pressure perovskite-structured polymorph of calcium silicate (CaSiO3 ). This mineral-expected to be the fourth most abundant in the Earth-has not previously been found in nature...
March 7, 2018: Nature
M F S Casagrande, D M Bonotto
This paper describes an alternative method for evaluating gross alpha and beta radioactivity in waters by using γ-rays analysis performed with hyper-pure germanium detector (HPGe). Several gamma emissions related to α and β- decays were used to provide the activity concentration data due to natural radionuclides commonly present in waters like 40 K and those belonging to the 238 U and 232 Th decay series. The most suitable gamma emissions related to β- decays were 214 Bi (1120.29 keV, 238 U series) and 208 Tl (583...
July 2018: Applied Radiation and Isotopes
Yaoyao Huang, Yang Hu, Lvcun Chen, Tao Yang, Hanfang Huang, Runping Shi, Peng Lu, Chenghua Zhong
Low-cost biosorbents (ginkgo leaf, osmanthus leaf, banyan leaf, magnolia leaf, holly leaf, walnut shell, and grapefruit peel) were evaluated in the simultaneous removal of La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Yb3+, Lu3+, UO22+, Th4+, Y3+, Co2+, Zn2+, Ni2+, and Sr2+ from aqueous solutions. In single metal systems, all adsorbents exhibited good to excellent adsorption capacities toward lanthanides and actinides. In a simulated multicomponent mixed solution study, higher selectivity and efficiency were observed for Th4+ over other metal cations, with ginkgo leaves providing the highest adsorptivity (81...
2018: PloS One
Giorgia Cinelli, Tore Tollefsen, Peter Bossew, Valeria Gruber, Konstantins Bogucarskis, Luca De Felice, Marc De Cort
The European Atlas of Natural Radiation is a collection of maps displaying the levels of natural radioactivity caused by different sources. It has been developed and is being maintained by the Joint Research Centre (JRC) of the European Commission, in line with its mission, based on the Euratom Treaty: to collect, validate and report information on radioactivity levels in the environment of the EU Member States. This work describes the first version of the European Atlas of Natural Radiation, available in digital format through a web portal, as well as the methodology and results for the maps already developed...
February 26, 2018: Journal of Environmental Radioactivity
Pei Zhao, Xiang Zhao, Masahiro Ehara
Th@C76 has been studied by density functional theory combined with statistical mechanics calculations. The results reveal that Th@ T d (19151)-C76 satisfying the isolated pentagon rule possesses the lowest energy. Nevertheless, considering the enthalpy-entropy interplay, Th@ C1 (17418)-C76 with one pair of adjacent pentagons is thermodynamically favorable at elevated temperatures, which is reported for the first time. The bonding critical points in both isomers were analyzed to disclose covalent interactions between the inner Th and cages...
March 19, 2018: Inorganic Chemistry
V Pereda-Loth, X Franceries, A S Afonso, A Ayala, B Eche, D Ginibrière, G Gauquelin-Koch, M Bardiès, L Lacoste-Collin, M Courtade-Saïdi
Astronauts are exposed to microgravity and chronic irradiation but experimental conditions combining these two factors are difficult to reproduce on earth. We have created an experimental device able to combine chronic irradiation and altered gravity that may be used for cell cultures or plant models in a ground based facility. Irradiation was provided by thorium nitrate powder, conditioned so as to constitute a sealed source that could be placed in an incubator. Cell plates or plant seedlings could be placed in direct contact with the source or at various distances above it...
February 2018: Life Sciences in Space Research
D L Hoffmann, C D Standish, M García-Diez, P B Pettitt, J A Milton, J Zilhão, J J Alcolea-González, P Cantalejo-Duarte, H Collado, R de Balbín, M Lorblanchet, J Ramos-Muñoz, G-Ch Weniger, A W G Pike
The extent and nature of symbolic behavior among Neandertals are obscure. Although evidence for Neandertal body ornamentation has been proposed, all cave painting has been attributed to modern humans. Here we present dating results for three sites in Spain that show that cave art emerged in Iberia substantially earlier than previously thought. Uranium-thorium (U-Th) dates on carbonate crusts overlying paintings provide minimum ages for a red linear motif in La Pasiega (Cantabria), a hand stencil in Maltravieso (Extremadura), and red-painted speleothems in Ardales (Andalucía)...
February 23, 2018: Science
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