Volume 110, Issue 5

(2R,2′S)-2,2′-oxybis-( N,N -didecylpropanamide) ( cis -mTDDGA) and (2R,2′R)-2,2′-oxybis-( N,N -didecylpropanamide) ( trans -mTDDGA) were studied using time-resolved laser fluorescence spectroscopy (TRLFS), vibronic side-band spectroscopy (VSBS) and density functional theory calculations (DFT) to find reasons for their different extraction properties. Stability constants of the respective Cm(III) and Eu(III) complexes show cis -mTDDGA to be the superior ligand which is in agreement with results from extraction experiments. cis -mTDDGA extracts Cm(III) and Eu(III) as 1:3 complexes. In case of trans -mTDDGA, 1:2 complexes of the form [M( trans -mTDDGA) 2 (η 1 -NO 3 )(H 2 O) 2 ] 2+ (M = Cm, Eu) are extracted additionally to the 1:3 complexes. VSBS and DFT confirm the presence of inner-sphere nitrate in the 1:2 complex.

The study of the formation of radiolytic products, such as molecular hydrogen and nitrous acid, is of primary importance in the reprocessing of spent nuclear fuel and the storage of aqueous solutions containing radioactive materials. The radiolytic yields of molecular hydrogen, nitrous acid and nitrous oxide from alpha radiolysis of nitric acid solutions containing plutonium have been experimentally investigated. The results have shown that the yields of radiolytic products depends on the nitric acid concentration as well as the oxidation state of plutonium. However, the influence of plutonium oxidation state on radiolytic yields is less notable as the nitric acid concentration increases. Molecular hydrogen production decreases with increasing nitric acid concentration while nitrous acid and nitrous oxide productions increase. While radiolytic yields from plutonium(IV) nitric acid solutions have been previously investigated, this study provides radiolytic yields from alpha radiolysis of plutonium(III) and plutonium(VI) nitric acid solutions for molecular hydrogen, nitrous acid and nitrous oxide. These information provide insight into the role played by plutonium redox behaviour on the formation of radiolytic products.

With the rapid development of nuclear energy, how to safely and efficiently dispose of radioactive waste solution has become an urgent environmental problem of public concern. It is of great significance to construct a new type of high-efficiency adsorbent material to recover uranium from nuclear waste solution. In this work, the Ti 3 C 2 T x material (an emerging two-dimensional inorganic layered material) with a stable layered structure was used as the matrix, and the amidoxime functionalized MXene composite material (PAO/Ti 3 C 2 T x ) was synthesized by in-situ polymerization. The amidoxime-functionalized Ti 3 C 2 T x showed excellent capacity to capture U(VI), with a maximum adsorption capacity of 98.04 mg/g at 25 °C, which was significantly better than that of Ti 3 C 2 T x , and the adsorption selectivity for U(VI) was greatly improved. The adsorption was conformed to Langmuir isotherm model and pseudo-second-order kinetic model. In addition, the adsorbed UO22+ could be effectively desorbed by 0.1 M HNO3, and the adsorption performance of PAO/Ti 3 C 2 T x did not decrease significantly after 5 adsorption/desorption cycles. The results of ionic strength experiment, FT-IR, SEM, and XPS jointly indicated that adsorption mechanism of U(VI) on PAO/Ti 3 C 2 T x was the combined effect of the amidoxime group and -O and -OH active groups on the surface of Ti 3 C 2 T x , mainly inner complexation. These advantages make PAO/Ti 3 C 2 T x composite a highly potential U(VI) adsorbent with great application prospects.

An artificial neural network (ANN) algorithm was developed to predict isotopic composition of five Pu isotopes ( 238 Pu, 239 Pu, 240 Pu, 241 Pu, and 242 Pu) of high burn-up Pu samples. The study was carried out using the most complex but informative gamma energy region of Pu gamma spectra, 90–106 keV. This region has remained futile, due to the overlapping nature of the gamma emission lines and X-rays emitted by U, Pu, and Np. A backpropagation neural network algorithm based ANN with error minimization using the steepest gradient method was built with the help of normalized gamma spectra for ∼800 samples. The paper discusses the optimization of hidden neuron number and the layer design for best prediction. With the exception of 242 Pu, the prediction accuracy and precision of the proposed technique was found to be ∼3% for all other isotopes of Pu.

The iron oxide surface was modified with succinic acid moiety and the adsorbent obtained, Fe-SUC, was evaluated for the adsorption of U(VI) (Uranium (VI)) from aqueous solution. The Fe-SUC was characterized by FT-IR (Fourier Transform Infrared Spectroscopy), Raman spectroscopy, thermogravimetry, X-ray diffraction, SEM-EDX (Scanning Electron Microscope - Energy-dispersive X-ray Spectroscopy), and particle size analysis. The adsorption behavior of U(VI) on Fe-SUC was studied as a function of pH, contact time, and concentration of U(VI) in the aqueous phase. The adsorption of U(VI) increased with increase in the pH of aqueous phase, and the adsorption saturation occurred at pH = 6. The kinetic data obtained for the adsorption of U(VI) on Fe-SUC were modeled with the pseudo-first-order and pseudo-second-order rate models. Similarly, the U(VI) adsorption isotherm was fitted with Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherm models. The Langmuir adsorption capacity of U(VI) on Fe-SUC was about ∼176 mg g −1 . The selectivity of the adsorbent toward U(VI) was evaluated in the presence of several possible interfering ions. The adsorbed U(VI) was recovered by 0.5 M sodium carbonate solution and the spent adsorbent was tested for its reusability.

The electrochemical reduction of U(VI) and Re(VII) ions on Pt and Mo metals are discussed. The electrochemical behavior of U(VI) and Re(VII) in hydrochloric acid media was investigated using various electrochemical techniques. By analyzing the cyclic voltammogram of U(VI) and Re(VII) recorded on Pt electrode, a series of electrochemical reactions associated with uranium and rhenium were recognized, indicating that U(VI) and Re(VII) undergoes a single-step electron and multistep electron process under experimental conditions, respectively. The reduction of U(VI) and Re(VII) was found to be controlled by charge transfer and diffusion in hydrochloric acid media. The diffusion coefficient of U(VI) and Re(VII)was determined to be 4.22–5.99 × 10 −6  cm 2  s −1 and 1.50–2.90 × 10 −5  cm 2  s −1 , respectively, and the activation energy for the diffusion are calculated to be 18.12 kJ mol −1 and 14.52 kJ mol −1 by cyclic voltammetry at different temperatures. The reduction process of U(VI) and Re(VII) at hydrochloric acid is further studied by potentiostatic electrolysis. It is feasible to realize the reduction of uranium and rhenium from aqueous solution by electrolysis.

Based on the one-dimensional diffusion theory, the diffusion parameters were obtained from numerical fitting by the Cyclic Initial Value (CIV) program written by MATLAB. Taking the through-diffusion experimental of cesium (stable isotope 133 Cs) as an example, on the premise of ensuring accuracy, fitting calculation was used to obtain the diffusion equilibrium time of Cs in different lengths bentonite column. The fitting results of diffusion test for tritium water (HTO) and Cs are both very well. The calculation results of the equilibrium time for Cs diffusion show that the equilibrium time obtained by CIV is less than the experimental period in both groundwater (GW) and seawater (SW). In GW environment, when the sensitivity is at the maximum setting value, the diffusion coefficient of Cs in 1.5 cm bentonite column could be calculated in a shorter period of time. Compared with the experimental period, the time was shortened by 110 days. The main purpose is to verify the feasibility of CIV through the experimental data of Cs in different column lengths. The CIV program can also be used to fit and calculate the experimental data of other ongoing diffusion experiments and get the equilibrium time required for diffusion experiments. It shows that the proposed models offer the advantages of saving experimental time and reducing experimental waste.

The radioisotope Cr-51 was exploited for studying the chromium adsorption behavior in aqueous media of alumina in aqueous media. Where, it represents 1.8% by weight and exists in earth’s crust in different forms. Factors affecting this adsorption behavior are pH, amount of alumina and humic acid presence. In case of pH adsorption curves, three different areas under peak can be described based on pH changes which lead to the formation of different species too. The first area is the maximum constant adsorption at pH, range 1–3, the second one is adsorption decreasing with increasing pH through pH range 4–7 and the third one is step-down adsorption at higher pH range. The increasing amount of alumina leads to increase in the percent adsorption, where 10 and 2 g/l alumina were found to have 100% while in case of 0.2 g/l it is 80%. The presence of humic acid decreases the adsorption of chromate with increasing pH to be 30% comparing to 80% in case of 0.2 g/l alumna at pH 2. This can be also indicated by adsorption capacity which is found to be 436.8 μg/g in case of 0.2 g alumina; and it decreases in presence of Humic Acid (HA) to 145.8 μg/g at same weight of alumina. Also, the equilibrium capacities are found as 54.6 μg/g for 2 g/l and 1.2 μg/g for 10 g/l. Triple layer model (TLM) was used for simulation of chromium adsorption behavior in presence of alumina with the applied conditions of study. The results showed high coincidence with the practically found data.

Indium- 111 ( 111 In) has an appropriate half-life ( T 1/2  = 67 h) and energy characteristics for cancer diagnosis via γ -ray imaging and cancer therapy with Auger electrons. The aim of our study is to evaluate the potential of [ 111 In]In-DO3A-NHS-nimotuzumab as a theranostic agent for radioimmunoimaging (RII) and radioimmunotherapy (RIT) against human glioma xenografts in mice. We explored the chelators DO3A-NHS and DOTA-p-SCN-Bz to optimize 111 In radiolabeling efficiency of nimotuzumab. The radiopharmaceuticals were purified by PD-10 mini-column and their in vitro stabilities were assessed. We investigated the biodistribution of [ 111 In]In-DO3A-NHS-nimotuzumab as it had relatively superior labeling efficiency and stability in vitro . We conducted SPECT imaging on mice bearing glioma (U87MG) xenografts, which were injected with ∼3.7 MBq of [ 111 In]In-DO3A-NHS-nimotuzumab. The in vivo radiotherapeutic effects of [ 111 In]In-DO3A-NHS-nimotuzumab was analyzed via injecting a single 37 MBq dose, 2 × 18 MBq doses, or 2 × 37 MBq doses into mice bearing U87MG xenografts. The control groups were administered either 30 μg nimotuzumab or saline. The radiochemical yields of [ 111 In]In-DO3A-NHS-nimotuzumab and [ 111 In]In-DOTA-p-SCN-Bz-nimotuzumab were > 85% and > 75%, respectively. [ 111 In]In-DO3A-NHS-nimotuzumab had > 95% radiochemical purity and was more stable in vitro than [ 111 In]In-DOTA-p-SCN-Bz-nimotuzumab. Biodistribution study demonstrated that [ 111 In]In-DO3A-NHS-nimotuzumab was highly stable in vivo . SPECT imaging disclosed that [ 111 In]In-DO3A-NHS-nimotuzumab had excellent targeted tumor uptake and retained in tumors for 24 and 72 h. All [ 111 In]In-DO3A-NHS-nimotuzumab treatments substantially inhibited tumor growth over the controls. The 2 × 37 MBq treatment was particularly efficacious, and presented with survival time prolonged by ≤66 days. In contrast, the survival time of the control group was only 30 days. In our study, we developed an optimized synthesis protocol for radiopharmaceutical 111 In-DO3A-NHS-nimotuzumab and demonstrated that it is a promising theranostic agent. It could be highly efficacious in RII and RIT against EGFR-expressing glioma.

This study ailm was to fabricate and investigate the gamma photon shielding efficiency of antimony (Sb) doped polymer resin composites. The orthophthalic unsaturated polyester resin (C 16 O 7 H 14 ) and antimony powder have been used as matrix and filler material, respectively. Gamma radiation shielding capacities of the polymer resin composites doped with 325 mesh sized-antimony particles from 5 to 20 wt% have been investigated. Experimental measurements of the samples have been obtained using an HPGe detector equipped with gamma spectrometer by 241 Am, 133 Ba, 57 Co, 22 Na, 137 Cs, 152 Eu, 54 Mn and 60 Co radioactive point sources varying from 59.5 to 1408.0 keV energies. To explore the gamma-ray attenuation features, linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective atomic number (Zeff), the radiation protection efficiency (RPE) were evaluated. According to the obtained results, it was found that Sb(20%) showed the superior radiation shielding capacity than the other samples. The measured data have been compared with those of WinXCOM, and they were found to be in a good agreement with each other.