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J R Griswold, D G Medvedev, J W Engle, R Copping, J M Fitzsimmons, V Radchenko, J C Cooley, M E Fassbender, D L Denton, K E Murphy, A C Owens, E R Birnbaum, K D John, F M Nortier, D W Stracener, L H Heilbronn, L F Mausner, S Mirzadeh
Actinium-225 and (213)Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of (225)Ac. The high-energy proton spallation reaction on natural thorium metal targets has been utilized to produce millicurie quantities of (225)Ac. The results of sixteen irradiation experiments of thorium metal at beam energies between 78 and 192MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridge National Laboratory (ORNL)...
September 28, 2016: Applied Radiation and Isotopes
Alvaro Muñoz-Castro, R Bruce King
The experimentally characterized endohedral metallic fullerenes involving the small C28 cage, has shown to be able to encapsulate zirconium, hafnium, and uranium atoms, among other elements. Here, we explore the formation and nature of concentric bonds from purely d- to f-block elements, given by Zr, Hf, and uranium, along a borderline metal between such blocks, thorium. We explore the interplay of d- and f-orbitals in the chemistry of the early actinides, where the features of a d- or f-block metal can be mixed...
October 24, 2016: Journal of Computational Chemistry
Adel Mesbah, Nicolas Clavier, M Janeth Lozano-Rodriguez, Stephanie Szenknect, Nicolas Dacheux
Pure powdered compounds with a general formula Th1-xErx(SiO4)1-x(PO4)x belonging to the zircon-xenotime family were successfully synthesized under hydrothermal conditions (250 °C, 7 days) as recently reported for the preparation of coffinite. Therefore, a thorough, combined PXRD, EDX, EXAFS, Raman, and FTIR analysis showed the formation of a solid solution in agreement with Vegard's law. Moreover, the examination of the local structure shows that the Th-O distances remain close to those found in ThSiO4, whereas the Er-O distances show a significant decrease from 2...
October 17, 2016: Inorganic Chemistry
Hilary P Emerson, Katherine A Hickok, Brian A Powell
Previous field experiments have suggested colloid-facilitated transport via inorganic and organic colloids as the primary mechanism of enhanced actinide transport in the subsurface at former nuclear weapons facilities. In this work, research was guided by the hypothesis that humic substances can enhance tetravalent actinide (An(IV)) migration by coating and mobilizing natural colloids in environmental systems and increasing An(IV) sorption to colloids. This mechanism is expected to occur under relatively acidic conditions where organic matter can sorb and coat colloid surfaces and facilitate formation of ternary colloid-ligand-actinide complexes...
October 7, 2016: Journal of Environmental Radioactivity
Alasdair Formanuik, Fabrizio Ortu, Christopher Inman, Andrew Kerridge, Ludovic Castro, Laurent Maron, David Paul Mills
Improving our comprehension of diverse CO2 activation pathways is of vital importance for the widespread future utilization of an abundant greenhouse gas. CO2 activation by uranium(III) complexes is now relatively well understood, with oxo/carbonate formation predominating as CO2 is readily reduced to CO, but isolated thorium(III) CO2 activation is unprecedented. We show that the thorium(III) complex, [Th(Cp'')3] (1, Cp'' = {C5H3(SiMe3)2-1,3}), reacts with CO2 to give the mixed oxalate-carboxylate thorium(IV) complex [{Th(Cp'')2[κ2-O2C{C5H3-3,3'-(SiMe3)2}]}2(µ-κ2:κ2-C2O4)] (3)...
October 7, 2016: Chemistry: a European Journal
Anne E V Gorden, Michael L McKee
The stability of Th(4+) to reduction in water is studied by DFT methods. The standard reduction potential (SRP) of homoleptic complexes including Th(H2O)9(4+), Th(H2O)10(4+), Th(NO3)4, Th(NO2)6(2-), Th(NO3)6(2-), Th(COT)2, Th(acac)4, ThCp4, ThF4, and ThCl4 have been investigated. The values vary widely (from -3.50 V for Th(OH)4 to -0.62 V for Th(NO3)4 depending on whether the ligands are redox active (noninnocent) or not. Several additional topics of thorium chemistry are explored, including the hydrolysis mechanism of ThO2(H2O)n, n = 1, 2, 4, and the solution phase nonzero dipole moment of ThCp4...
October 7, 2016: Journal of Physical Chemistry. A
Mary E Garner, Stephan Hohloch, Laurent Maron, John Arnold
Actinide complexes demonstrate unparalleled reactivity towards small molecules. However, utilizing these powerful transformations in a predictable and deliberate manner remains challenging. Therefore, developing actinide systems that not only perform noteworthy chemistry but also demonstrate controllable reactivity is a key goal. We describe a bis(NHC)borate thorium-bpy complex (1) that is capable of reductively cleaving the R-NC bond in a series of organic isocyanides. In contrast to most actinide-mediated bond activations, the dealkylation event mediated by 1 is remarkably general and yields very well-defined products that assist in mechanistic elucidation...
October 24, 2016: Angewandte Chemie
Elizabeth P Wildman, Gábor Balázs, Ashley J Wooles, Manfred Scheer, Stephen T Liddle
Despite the burgeoning field of uranium-ligand multiple bonds, analogous complexes involving other actinides remain scarce. For thorium, under ambient conditions only a few multiple bonds to carbon, nitrogen, oxygen, sulfur, selenium and tellurium are reported, and no multiple bonds to phosphorus are known, reflecting a general paucity of synthetic methodologies and also problems associated with stabilising these linkages at the large thorium ion. Here we report structurally authenticated examples of a parent thorium(IV)-phosphanide (Th-PH2), a terminal thorium(IV)-phosphinidene (Th=PH), a parent dithorium(IV)-phosphinidiide (Th-P(H)-Th) and a discrete actinide-phosphido complex under ambient conditions (Th=P=Th)...
2016: Nature Communications
Jian Lin, Geng Bang Jin, L Soderholm
A neutral-framework thorium oxohydroxosulfate hydrate has been isolated from aqueous solution. This microporous structure, which self-assembles without a templating agent, is built from [Th6(OH)4O4(H2O)6](12+) hexamers and thorium(IV) monomers linked through bridging sulfates. Solution conditions were chosen to enable an active competition between sulfate and hydroxide for thorium coordination. Synthetic requirements are discussed for this rare example of a thorium(IV) polynuclear complex containing mixed oxo-, hydroxo-, and sulfato-bridging moieties...
October 17, 2016: Inorganic Chemistry
Merve Sasmaz, Erdal Obek, Ahmet Sasmaz
This study focused on the ability of Lemna minor and Lemna gibba to remove U and Th in the tailing water of Keban, Turkey. These plants were placed in tailing water and individually fed to the reactors designed for these plants. Water and plant samples were collected daily from the mining area. The plants were ashed at 300°C for 1 day and analyzed by ICP-MS for U and Th. U was accumulated as a function of time by these plants, and performances between 110 % and 483 % for L. gibba, and between 218 % and 1194 % for L...
September 23, 2016: Bulletin of Environmental Contamination and Toxicology
Kara E Marsac, Pamela C Burnley, Christopher T Adcock, Daniel A Haber, Russell L Malchow, Elisabeth M Hausrath
This study compares high resolution forward models of natural gamma-ray background with that measured by high resolution aerial gamma-ray surveys. The ability to predict variations in natural background radiation levels should prove useful for those engaged in measuring anthropogenic contributions to background radiation for the purpose of emergency response and homeland security operations. The forward models are based on geologic maps and remote sensing multi-spectral imagery combined with two different sources of data: 1) bedrock geochemical data (uranium, potassium and thorium concentrations) collected from national databases, the scientific literature and private companies, and 2) the low spatial resolution NURE (National Uranium Resource Evaluation) aerial gamma-ray survey...
September 15, 2016: Journal of Environmental Radioactivity
Yuhui Ma, Jingkun Wang, Can Peng, Yayun Ding, Xiao He, Peng Zhang, Na Li, Tu Lan, Dongqi Wang, Zhaohui Zhang, Fuhong Sun, Haiqing Liao, Zhiyong Zhang
Cerium (Ce) and thorium (Th) are always thought to be chemically similar and have comparable toxic properties on living organisms. In the present study, the acute and chronic toxicity of these two elements to freshwater crustacean Daphnia magna were investigated in the modified reconstituted water (6mg/L KCl, 123mg/L MgSO4·7H2O, and 294mg/L CaCl2·2H2O in Milli-Q water, pH 7.8). It seemed that Ce and Th had comparable acute toxicity on Daphnia: 24/48h EC50 for Th and Ce were 7.3/4.7μM and 16.4/10.7μM, respectively...
September 14, 2016: Ecotoxicology and Environmental Safety
Janne Olsen Frenvik, Knut Dyrstad, Solveig Kristensen, Olav B Ryan
Targeted Thorium Conjugates (TTCs) are being explored as a potential future platform for specific tumour targeting pharmaceuticals. In TTCs the alpha emitting radionuclide thorium-227 ((227)Th) with a half-life of 18.697 days is labelled to targeting moieties, such as monoclonal antibodies (mAbs). The amount of daughter nuclide radium-223 ((223)Ra, t1/2 = 11.435 days) will increase during manufacture and distribution, and so a technology for purification is required to assure an acceptable level of (223)Ra is administrated to the patient...
September 15, 2016: Drug Development and Industrial Pharmacy
Yanliang Chen, Yuezhou Wei, Linfeng He, Fangdong Tang
To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method...
September 30, 2016: Journal of Chromatography. A
Ondřej Šrámek, Bedřich Roskovec, Scott A Wipperfurth, Yufei Xi, William F McDonough
The Earth's engine is driven by unknown proportions of primordial energy and heat produced in radioactive decay. Unfortunately, competing models of Earth's composition reveal an order of magnitude uncertainty in the amount of radiogenic power driving mantle dynamics. Recent measurements of the Earth's flux of geoneutrinos, electron antineutrinos from terrestrial natural radioactivity, reveal the amount of uranium and thorium in the Earth and set limits on the residual proportion of primordial energy. Comparison of the flux measured at large underground neutrino experiments with geologically informed predictions of geoneutrino emission from the crust provide the critical test needed to define the mantle's radiogenic power...
2016: Scientific Reports
Carla Roselli, Donatella Desideri, Maria Assunta Meli, Ivan Fagiolino, Laura Feduzi
Essential and toxic elements were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES), mass spectrometry (MS), and atomic absorption (AS) in meat of 14 migratory birds originating from central and northern Europe to provide baseline data regarding game meat consumed in central Italy. In all samples analyzed, cobalt (Co) and chromium (Cr) (total) levels were <0.326 mg/kgww. For nonessential or toxic elements, arsenic (As), barium (Ba), cadmium (Cd), stannous (Sn), thallium (Tl), tellurium (Te), titanium (Ti), cerium (Ce), lantanium (La), and uranium (U) concentrations were <0...
2016: Journal of Toxicology and Environmental Health. Part A
Erick Helmeczi, Yong Wang, Ian D Brindle
Short-wavelength infrared radiation has been successfully applied to accelerate the acid digestion of refractory rare-earth ore samples. Determinations were achieved with microwave plasma-atomic emission spectrometry (MP-AES) and dynamic reaction cell - inductively coupled plasma-mass spectrometry (DRC-ICP-MS). The digestion method developed was able to tackle high iron-oxide and silicate matrices using only phosphoric acid in a time frame of only 8min, and did not require perchloric or hydrofluoric acid. Additionally, excellent recoveries and reproducibilities of the rare earth elements, as well as uranium and thorium, were achieved...
November 1, 2016: Talanta
Opeyemi A Oyewo, Maurice S Onyango, Christian Wolkersdorfer
Transformation of agricultural waste such as banana peels into a valuable sorbent material has been proven effective and efficient in wastewater treatment. Further, transformation into nanosorbent to enhance the removal capacity of actinides (uranium and thorium) from synthetic and real mine water is extensively investigated in this study. The nanosorbent samples before and after adsorption were characterised by X-ray diffraction (XRD), Fourier transform infra-red (FTIR), zetasizer nanoseries and scanning electron microscopy (SEM) while the amount of radioactive substances adsorbed was determined by inductively coupled plasma optical emission spectroscopy...
November 2016: Journal of Environmental Radioactivity
Wenbo Lan, Sha Gao, Ying-Wu Lin, Lifu Liao, Xiaofeng Wang, Changming Nie
Theoretical calculations on the structure of Th(IV) complex containing N, N'- bis(3-allyl salicylidene)-o-phenylenediamine (BASPDA) were performed using density functional theory (DFT) at the B3LYP/6-311G** level. The geometrical structural parameters and infrared spectra results of the Th(BASPDA)2 from the calculation were compared with the parallel dislocated structure (PDS) obtained in laboratory. The calculated structural parameters were in good agreement with the experimental results. In addition, based on the calculations, a stereoisomer SFS (staggered finger " + " structure) of the Th(BASPDA)2 complex was forecasted by the analysis of a comprehensive method...
September 2016: Journal of Molecular Modeling
Urs B Hagemann, Katrine Wickstroem, Ellen Wang, Adam O Shea, Kristine Sponheim, Jenny Karlsson, Roger M Bjerke, Olav B Ryan, Alan S Cuthbertson
The clinical efficacy of the first approved alpha pharmaceutical, Xofigo (radium-223 dichloride, (223)RaCl2), has stimulated significant interest in the development of new alpha-particle emitting drugs in oncology. Unlike radium-223 ((223)Ra), the parent radionuclide thorium-227 ((227)Th) is able to form highly stable chelator complexes and is therefore amenable to targeted radioimmunotherapy. We describe the preparation and use of a CD33-targeted thorium-227 conjugate (CD33-TTC), which binds to the sialic acid receptor CD33 for the treatment of acute myeloid leukemia (AML)...
October 2016: Molecular Cancer Therapeutics
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