Simultaneous Separation of Actinium and Radium Isotopes from a Proton Irradiated Thorium Matrix.
ABSTRACT: A new method has been developed for the isolation of 223,224,225Ra, in high yield and purity, from a proton irradiated 232Th matrix. Herein we report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. A procedure involving the use of three columns in succession was developed, and the separation of 223,224,225Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based on previously measured excitation functions.
Project description:Actinium-225 (<sup>225</sup>Ac) can be produced with a linear accelerator by proton irradiation of a thorium (Th) target, but the Th also underdoes fission and produces 400 other radioisotopes. No research exists on optimization of the cation step for the purification. The research herein examines the optimization of the cation exchange step for the purification of <sup>225</sup>Ac. The following variables were tested: pH of load solution (1.5-4.6); rinse steps with various concentrations of HCl, HNO<sub>3</sub>, H<sub>2</sub>SO<sub>4</sub>, and combinations of HCl and HNO<sub>3</sub>; various thorium chelators to block retention; MP50 and AG50 resins; and retention of 20-45 elements with different rinse sequences. The research indicated that HCl removes more isotopes earlier than HNO<sub>3</sub>, but that some elements, such as barium and radium, could be eluted with ?2.5 M HNO<sub>3</sub>. The optimal pH of the load solution was 1.5-2.0, and the optimized rinse sequence was five bed volumes (BV) of 1 M citric acid pH 2.0, 3 BV of water, 3 BV of 2 M HNO<sub>3</sub>, 6 BV of 2.5 M HNO<sub>3</sub> and 20 BV of 6 M HNO<sub>3</sub>. The sequence recovered >90% of <sup>225</sup>Ac with minimal <sup>223</sup>Ra and thorium present.
Project description:Thorium (232Th), an actinoide element, is among the most common and naturally occurring radioactive materials distributed in our environment. Thorium has been used as a radiographic contrast agent (thorotrast) from 1930 to 1955, and many studies on its effects to the human body have been reported. Once thorium is injected in the body, the risk of cancer is increased by the direct bombardment from alpha-particle with high linear energy transfer during decay of Thorium. However, these many reports focus on the irradiation damage by long-term exposure of thorium. The acute toxicity of thorium is greater risk from the chemical toxicity than from the radiological toxicity. Here, we evaluated the effect of thorium from the stand point of chemical toxicity using yeast DNA microarray. In this experiment, genes that contribute to “C-compound and carbohydrate metabolism”, “energy”, and “cell rescue, defense and virulence” were significantly induced. These genes were classified into oxidative stress, glycogen and trehalose metabolism, sugar transport, and cell wall damage. On the contrary, only one gene related to DNA damage was detected. These results indicate that thorium causes the damage of cell wall and induces the oxidative stress. In order to overcome oxidative stress, yeast cells promote the glycogen and trehalose metabolisms and shift to anaerobic fermentation. Keywords: stress response Overall design: Series containes 3 hybridization results from independent biological samples, and each experiment have high and low power scanned data respectively.
Project description:This work presents results obtained using gamma spectrometry measurements of phosphogypsum samples on a non-fractionated (native) and fractionated phosphogypsum byproduct. The phosphogypsum was divided into particles size fractions within the range of <?0.063, 0.063-0.090, 0.090-0.125, 0.125-0.250, and over 0.250 mm and analyzed after reaching radioactive equilibrium using high-resolution gamma spectrometry technique. It was found that there is no significant differentiation between 226Ra distribution among particular grain size fractions of this material; however, tendency for preferential retention of radionuclides in particular grain size fractions is observed. The detailed analysis of results revealed that radium is preferentially retained in smaller grain size fractions, whereas lead and thorium in coarse fractions. The results indicate that overall 226Ra activity concentrations between particular fractions of phosphogypsum vary globally between -?34 and +?47% regarding non-fractionated material, and for 210Pb activity concentration, fluctuations are found between -?26 up and +?38%. Presumably, the mechanism of radium incorporation into gypsum phase is based on a sequence of radium bearing sulfate phases formation followed by a surface adsorption of these phases on the calcium sulfate crystals, whereas for lead and thorium ions, rather incorporation into crystal lattice should be expected as more likelihood process.
Project description:The alpha particle emitter Radium-223 dichloride (223RaCl2) has recently been approved for treatment of late-stage bone metastatic prostate cancer. There is considerable interest in studying this new agent outside of the clinical setting, however the supply of 223Ra is limited and expensive. We have engineered a 223Ra microgenerator using traces of 227Ac previously generated from cyclotron-produced 225Ac. Radiochemically pure 223RaCl2 was made, characterized, evaluated in vivo, and the source was recovered in high yield for regeneration of the microgenerator.
Project description:Reaction of [Th(I)(NR2)3] (R = SiMe3) (2) with KECPh3 (E = O, S) affords the thorium chalcogenates, [Th(ECPh3)(NR2)3] (3, E = O; 4, E = S), in moderate yields. Reductive deprotection of the trityl group from 3 and 4 by reaction with KC8, in the presence of 18-crown-6, affords the thorium oxo complex, [K(18-crown-6)][Th(O)(NR2)3] (6), and the thorium sulphide complex, [K(18-crown-6)][Th(S)(NR2)3] (7), respectively. The natural bond orbital and quantum theory of atoms-in-molecules approaches are employed to explore the metal-ligand bonding in 6 and 7 and their uranium analogues, and in particular the relative roles of the actinide 5f and 6d orbitals.
Project description:<h4>Background</h4>The economic value of unconventional natural gas resources has stimulated rapid globalization of horizontal drilling and hydraulic fracturing. However, natural radioactivity found in the large volumes of "produced fluids" generated by these technologies is emerging as an international environmental health concern. Current assessments of the radioactivity concentration in liquid wastes focus on a single element-radium. However, the use of radium alone to predict radioactivity concentrations can greatly underestimate total levels.<h4>Objective</h4>We investigated the contribution to radioactivity concentrations from naturally occurring radioactive materials (NORM), including uranium, thorium, actinium, radium, lead, bismuth, and polonium isotopes, to the total radioactivity of hydraulic fracturing wastes.<h4>Methods</h4>For this study we used established methods and developed new methods designed to quantitate NORM of public health concern that may be enriched in complex brines from hydraulic fracturing wastes. Specifically, we examined the use of high-purity germanium gamma spectrometry and isotope dilution alpha spectrometry to quantitate NORM.<h4>Results</h4>We observed that radium decay products were initially absent from produced fluids due to differences in solubility. However, in systems closed to the release of gaseous radon, our model predicted that decay products will begin to ingrow immediately and (under these closed-system conditions) can contribute to an increase in the total radioactivity for more than 100 years.<h4>Conclusions</h4>Accurate predictions of radioactivity concentrations are critical for estimating doses to potentially exposed individuals and the surrounding environment. These predictions must include an understanding of the geochemistry, decay properties, and ingrowth kinetics of radium and its decay product radionuclides.
Project description: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. The method is highly sensitive with a detection limit of 0.45 nM. Furthermore, the sensor is selective: other metal ions (e.g., UO22+, Pb2+, Cu2+, Ni2+, Hg2+, Zn2+, As3+, Mg2+, and Ca2+) with concentrations of up to 3 orders of magnitude greater than that of Th4+ would not interfere with Th4+detection. In addition, simulated water samples were successfully analyzed. Our developed computation-assisted sensing strategy should find useful applications in the development of nanopore sensors for other metal ions.
Project description:In this investigation, natural radioactive contents in tiles manufactured in Nigeria and tiles imported from China were measured using gamma ray spectroscopy. High Purity Germanium detector was used to estimate the concentrations of some radioisotopes present in 17 samples of various tiles from Nigeria and China. The average activity concentrations of 226Ra, 232Th, and 40K for the tiles were found to be 68.2?±?0.5; 173.9?±?9.2 and 490?±?15?Bq/kg and 58.2?±?0.5, 161.5?±?9.4 and 455.7?±?15.1?Bq/kg for the tiles from Nigeria and China respectively. Radiological hazard indices such as absorbed dose rate, radium equivalent activity, external Hazard Index (Hex), internal Hazard Index (Hin), Annual Effective Dose (mSv/y), Gamma activity Index (I?) and Alpha Index (I?) were determined for both kind of tiles from Nigeria and China. The mean values obtained were: 354.56 and 317.16?Bq/kg; 169.22 nGyh-1 and 153.92 nGyh-1; 0.95 and 0.87; 1.14 and 1.08; 1.59?mSv/y and 1.52?mSv/y; 1 and 1.15 and; 0.34 and 0.29 respectively. The mean value of radium equivalent obtained in this study is less than that of the international reference value of 370?Bq/kg for the both kind of tiles.
Project description:Targeted ? therapy (TAT) offers the potential for the targeted delivery of potent ?-particle-emitting radionuclides that emit high linear energy transfer radiation. This leads to a densely ionizing radiation track over a short path. Localized radiation induces cytotoxic, difficult-to-repair, clustered DNA double-strand breaks (DSBs). To date, radium-223 (223Ra) is the only TAT approved for the treatment of patients with metastatic castration-resistant prostate cancer. Thorium-227 (227Th), the progenitor nuclide of 223Ra, offers promise as a wider-ranging alternative due to the availability of efficient chelators, such as octadentate 3,2-hydroxypyridinone (3,2-HOPO). The 3,2-HOPO chelator can be readily conjugated to a range of targeting moieties, enabling the generation of new targeted thorium-227 conjugates (TTCs). This review provides a comprehensive overview of the advances in the preclinical development of TTCs for hematological cancers, including CD22-positive B cell cancers and CD33-positive leukemia, as well as for solid tumors overexpressing renal cell cancer antigen CD70, membrane-anchored glycoprotein mesothelin in mesothelioma, prostate-specific membrane antigen in prostate cancer, and fibroblast growth factor receptor 2. As the mechanism of action for TTCs is linked to the formation of DSBs, the authors also report data supporting combinations of TTCs with inhibitors of the DNA damage response pathways, including those of the ataxia telangiectasia and Rad3-related protein, and poly-ADP ribose polymerase. Finally, emerging evidence suggests that TTCs induce immunogenic cell death through the release of danger-associated molecular patterns. Based on encouraging preclinical data, clinical studies have been initiated to investigate the safety and tolerability of TTCs in patients with various cancers.
Project description:Inter- and intramolecular C-H bond activations by thorium metallacyclopropene complexes were comprehensively studied. The reduction of [?5-1,2,4-(Me3C)3C5H2]2ThCl2 (1) with potassium graphite (KC8) in the presence of internal alkynes (PhC 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CR) yields the corresponding thorium metallacyclopropenes [?5-1,2,4-(Me3C)3C5H2]2Th(?2-C2Ph(R)) (R = Ph (2), Me (3), iPr (4), C6H11 (5)). Complexes 3-5 derived from phenyl(alkyl)acetylenes are very reactive resulting in an intramolecular C-H bond activation of the 1,2,4-(Me3C)3C5H2 ligand. In contrast, no intramolecular C-H bond activation is observed for the diphenylacetylene derived complex 2, but it does activate ?-C-H bonds in pyridine or carbonyl derivatives upon coordination. Density functional theory (DFT) studies complement the experimental studies and provide additional insights into the observed reactivity.