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The density of aqueous solutions containing actinide nitrates is an important parameter for process design, equipment design, and remote operation/control. It is also significantly important for the estimation of atom densities during criticality calculations and related experiments involving actinide solutions. Using a massive database of 1353 points consisting of in-house-generated data as well as data published in the literature, a robust estimation of the coefficients of a re-parameterized and dimensionally consistent form of density equation was performed in the following range of parameters: U(VI) concentration 0 to 1330 g/L, Pu(IV) concentration 0 to 1201 g/L, HNO3 concentration 0 to 15.8 M, and temperature range of 283.15 to 373.15 K. This paper lists the details of the new database, the newly estimated coefficients, and the performance evaluation of the proposed re-parameterized dimensionally consistent equations. [ABSTRACT FROM AUTHOR]

Homogeneous aqueous solution nuclear reactors have many advantages in the production of medical isotopes. However, the fuel precipitation problem must be addressed in transitioning the technology from research to a commercial industrial environment. The turbidity value can indirectly reflect the amount of precipitation in the fuel solution. This article systematically measured the turbidity values of fuel solutions under different nitric acid concentrations, temperatures and uranium concentrations, and studied their effects on the precipitate formation of uranyl nitrate fuel, provided some help for understanding the fuel properties of homogeneous aqueous solution nuclear reactor. [ABSTRACT FROM AUTHOR]

AbstractMedical radioisotope production using neutron irradiation via fission reaction requires a sufficient neutron source. The Kartini reactor has been proposed and studied to become a neutron source for radioisotope production under the Subcritical Assembly for 99Mo Production (SAMOP) project, which uses uranyl nitrate solution as the irradiation target. A full-scale experiment involving a liquid fission product is difficult to conduct and requires facility rearrangement to reduce the risk of contamination. Although a small-batch experiment is safer to perform, a pre-experimental assessment is necessary to address the practicality of production and the accompanying problems. The goals of this assessment are (1) to characterize the Kartini reactor irradiation facilities’ flux through experiment and Monte Carlo benchmark simulation, (2) to predict the irradiation product inventory in relation to the variation of uranium concentration and the measured flux, and (3) to predict the irradiated sample gamma spectrum reading using high-purity germanium detector simulation. The irradiation simulation uses natural uranium as a control parameter, which caused the irradiation inventory dominated by actinides from transmutation. The simulation also presents the possibility of instant small-batch 99Mo production using the measured Lazy Susan facilities’ flux from a neutronic perspective. The qualitative assessment of the predicted irradiation inventory and its spectrum reading from different sample concentrations are discussed along with the recommendation and possible action to improve the experiment or future production process. [ABSTRACT FROM AUTHOR]

This study focuses on the Medical Isotope Production Reactor (MIPR), an aqueous homogeneous reactor utilized for synthesizing medical isotopes like 99Mo. A pivotal aspect of MIPR's functionality involves the fuel solution's complex chemical interactions, particularly during reactor operation. These interactions result in the formation of precipitates, notably water filamentous uranium ore and columnar uranium ore, which can impact reactor performance. The research presented here delves into the reactions between liquid fuel uranyl nitrate and key radiolytic products, employing simulation calculations complemented by experimental validation. This approach facilitates the identification of uranium precipitate types and their formation conditions under operational reactor settings. Additionally, the article explores strategies to mitigate the formation of specific uranium precipitates, thereby contributing to the efficient and stable operation of MIPR. [ABSTRACT FROM AUTHOR]

This study focuses on the Medical Isotope Production Reactor (MIPR), an aqueous homogeneous reactor utilized for synthesizing medical isotopes like 99Mo. A pivotal aspect of MIPR’s functionality involves the fuel solution’s complex chemical interactions, particularly during reactor operation. These interactions result in the formation of precipitates, notably water filamentous uranium ore and columnar uranium ore, which can impact reactor performance. The research presented here delves into the reactions between liquid fuel uranyl nitrate and key radiolytic products, employing simulation calculations complemented by experimental validation. This approach facilitates the identification of uranium precipitate types and their formation conditions under operational reactor settings. Additionally, the article explores strategies to mitigate the formation of specific uranium precipitates, thereby contributing to the efficient and stable operation of MIPR.

The traditional evaporation process has obvious disadvantages when treating uranyl nitrate with a uranium concentration less than 10 g/L, such as more ancillary equipment, high energy consumption, and high cost. By contrast, nanofiltration equipment has low integration, and multivalent cations can be rejected effectively by nanofiltration membranes. In this work, a spiral-wound DK1812 nanofiltration membrane with an area of 0.325 m² was used to treat a uranium nitrate solution with a uranium concentration of 10 g/L. The uranium concentration in the permeate is 16.91 mg/L, which means that the uranium rejection rate is 99.83% and the permeate flux of the solution is 71.1 L/(m²·h) under the conditions of a feed temperature of 30°C, a tangential velocity of 30 cm/s, and a transmembrane pressure of 1.5 MPa. [ABSTRACT FROM AUTHOR]

Although applied nuclear energy technology is constantly improving, the threat of radioactive contamination has always been inevitable. The decontamination coating method is a new nuclear emergency decontamination technology. In this study, a smart strippable polymer coating containing EDTA and Bromo-PADAP as color detectors was designed to detect and remove the contaminant containing uranyl nitrate. The smart polymer coating changes from purple to brown due to the absorption of contaminants, which shows a high color difference of about 47. The results of an evaluation of FT-IR, TGA/DSC, and liquid scintillation tests well prove the presence of uranium ions in the coating. Decontamination factors in this coating have been shown to be above 99% at 2000 ppm of uranyl nitrate hexahydrate. The two types of glycerin content and polyvinylpyrrolidone polymer with different weights investigated. Finally, the PVA/6K90 polymer solution was obtained with optimal formulation and flexible film. [ABSTRACT FROM AUTHOR]

The decontamination of structures with radioactive substances is one of the most important areas of environmental chemistry. In this study, an intelligent polymeric coating containing a Br-PADAP detector was made to identify and remove the uranyl nitrate contaminant (UO2(NO3)2.6H2O). In this study, the effect of pH was investigated for the first time. Also, the parameters of different substrates, detector concentration, contaminant drying temperature, coating drying temperature, and mechanical properties of the contaminant adsorption were investigated. The results of an evaluation of FT-IR, TGA, and liquid scintillation tests well prove the presence of uranium ions in the coating. The polymer coating containing the EDTA and Br-PADAP detector becomes purple to brown by absorbing a contaminant solution containing uranium ions. Quantitative evaluation based on MATLAB software image processing methods also shows a color change. Decontamination factors (DFs) in this coating were shown to be above 97% at 2000 ppm, and higher than in previous studies. The polymer solution was obtained with optimal formulation and flexible film.

Application of proteomics technology screening of uranyl nitrate exposure induced CHO-K1 differentially expressed proteins, provide data for the research of uranium toxicity mechanism.CHO-K1 cells were exposed to 500 μmol/L uranyl nitrate for 24 h. Taking the difference factor more than 1.5 times and the difference significance less than 0.05 as the standard, tandem mass tag (TMT) proteomics technology was used to screen differentially expressed proteins, and bioinformatics technology was applied to differentially expressed proteins for cluster analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and protein interaction analysis. Protein identification results showed that 4 772 proteins were identified. 309 proteins with a differential expression of more than 1.5 times were screened in the uranyl nitrate exposure group, among which 164 proteins were up-regulated and 145 proteins were down-regulated. GO analysis results showed that the differentially expressed proteins were mainly involved in 1 086 biological processes, 282 cellular components and 377 molecular functions. KEGG analysis results showed that the differentially expressed proteins were mainly enriched in 40 signal transduction pathways. It is involved in ribosome biosynthesis, RNA transport, cofactor metabolism, Notch signaling pathway, phagosome, chromosome and related proteins, protein effection, circadian rhythm, IL-17 signaling pathway, lipid metabolism and other signaling pathways. Differential protein interaction network analysis showed that RPS3 A and RPS17 had the highest correlation. The results indicated that after exposure to 500 μmol/L uranyl nitrate for 24 h, proteins were differentially expressed, ribosome biosynthesis, RNA transport and other signaling pathways were changed, and proteins RPS3 A and RPS17 may be the key proteins in the damage of CHO-K1 cells induced by uranyl nitrate exposure. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A direct UV–Visible absorbance spectrophotometric method was developed for the simultaneous determination of uranium and nitric acid concentration in the PUREX process samples. The simulated system consisted of uranium and nitric acid in concentration range corresponding to reprocessing of spent nuclear fuel discharged from nuclear reactor was prepared. The absorbance of these samples was measured in the range of 400–470 nm at a scan speed of 100 nm/s and resultant spectra were recorded. The changes in wavelength maxima of U(VI) absorption spectrum at different nitric acid concentration was utilized to determine the concentration of uranium and nitric acid in the sample by orthogonal signal correction assisted principal component regression. After the principle component regression the RMSEP for test data (Uranium: 3–21 g/L and acidity: 2–12 M) were 0.7 g/L and 0.4 M respectively. This method is superior to conventional method being followed for routine analysis of plant control samples in view of minimizing the generation of radioactive analytical waste consisting other corrosive reagents and reducing radiation exposure to operators during analysis. This method is amenable for online monitoring also. [Display omitted] • UV Vis absorption spectral variation with acidities utilized for estimation of nitric acid concentration. • Principle component regression based multivariate analysis being carried out. • Mean normalisation and orthogonal signal correction being used as a preprocessing method. • Method is fast, devoid of corrosive analytical waste and amenable for online monitoring. • Developed method is applicable for uranium and nitric acid concentration estimation for process control analysis. [ABSTRACT FROM AUTHOR]

A simple remote aliquoting system (RAS) and a remote titration setup were developed to aid the analyses of highly radioactive samples inside a hot cell. The remote calibration of the RAS by a titrimetric method was validated and the systematic error and random error of the RAS were less than 1%. A method was developed for the determination of free acidity of solutions containing uranyl nitrate and plutonium nitrate without complexing agents. In this method, the first total acid was determined by a remote alkalimetric titration using a visual indicator. The free acidity was calculated by detecting the contribution of hydrolysable ions from the total acid. The relative standard deviation and recovery of free acidity for solutions having 0.092–0.56 M nitric acid using this method were < 1% and 100 ± 5% respectively for aliquots containing uranium 0.5–15.9 mg and plutonium 0.85–8.5 mg. Since no additional corrosive reagents were added in this method, the analytical waste solution generated was sent to process tanks directly without any treatment. The developed RAS and the free acidity titration method were adaptable to remote operation inside an alpha tight hot cell. [ABSTRACT FROM AUTHOR]

In this study, we describe the synthetic of uranyl nitrate ion functionalized MOFs linked by carboxyl, which displays block shape crystals structure. The as-prepared uranyl-MOF has been efficiently utilized as heterogeneous catalyst for selective aerobic oxidation of sulfides under visible-light irradiation. Photochemistry of extended MOFs including uranyl nitrate ion has been examined. The sulfoxidation reaction proceeds with good yields for a large variety of different sulfides. This process is carried out under visible light conditions, methanol as single solvent, and the uranyl-MOF material can be recycled up to five times. Sulfoxidation reaction mainly proceeds through an electron and energy transfer mechanism of oxygen in uranyl nitrate ion. In this study, we describe the synthetic of uranyl nitrate ion functionalized MOFs. The as-prepared uranyl-MOF was efficiently utilized as heterogeneous catalyst for selective aerobic oxidation of sulfides under visible-light irradiation. Photochemistry of extended MOFs including uranyl nitrate ion has been examined. [ABSTRACT FROM AUTHOR]

The effects of the separate and combined action of lead nitrate in a wide range of doses, uranyl nitrate, and chronic low-dose gamma irradiation on the formation of oxidative stress in the liver and the morpho-functional state of the thyroid gland of CBA mice (males) in the early and long-term periods after the end of exposure were studied. Complex and ambiguous changes in the parameters of the system of regulation of oxidative processes in the liver and morpho-physiological changes in the thyroid gland of mice were revealed. The scale and focus of these changes depended on the age of the animals, the chemical nature and concentration of the toxicants, and the time after the end of the treatment. Analysis of the literature and the obtained data allowed us to conclude that it is impossible to predict the consequences for mammals living in unfavorable environmental conditions by extrapolating the results obtained for high doses to small doses of pollutants. [ABSTRACT FROM AUTHOR]

Using laser-induced breakdown spectroscopy(LIBS) combined with internal standard method to achieve the aim of analyzing the information of uranium concentration in samples fast and quantitatively, the 300nm ~ 800nm spectra of 7ns, 20mJ nanosecond laser pulse induced graphite sheet coated with uranyl nitrate were detected by echelle spectrometer and ICCD, quantitative analysis of uranium samples coated with different concentrations was done. Theoretical analysis and experimental verifications were made to obtain the spectra data of U II 409.01nm, U II 367.01nm, C I 373.72nm, C II 383. 57nmand C III 378.94nm. The results show that there is a good linear relationship between normalized uranium intensity and uranium concentration when the sample concentration is lower than 5.0 x 10-3 mol/m² ( surface density was studied in this paper), the combination of LIBS and internal standard method could realize the rapid quantitative analysis of uranium concentration in the samples, this study provides reference for the rapid detection and analysis of trace uranium element in nuclear contamination and uranium ore. [ABSTRACT FROM AUTHOR]

Geopolymer is an amorphous cementitious material produced by geopolymerization using minerals or industrial waste as the main raw material under the action of activators. It can be used for safe treatment of heavy metal and radioactive pollution. This study applied molecular dynamics simulation to investigate the transport behaviour of uranyl nitrate in nanochannel of geopolymer, and focused on the influence of changes in the Si/Al ratio of geopolymer on the adsorption and diffusion of ions and water molecules. The simulation results described by density distribution, radial distribution function (RDF), hydrogen bonding network structure, mean square displacement (MSD) and diffusion coefficient. The density distribution shows that geopolymer has the strongest adsorption capacity for UO 2 2+, followed by NO 3 −, and finally H 2 O. The results also indicate that the changes in molecular composition of geopolymer have a significant impact on kinetic characteristics of UO 2 2+, NO 3 − and H 2 O. As the Si/Al ratio decreases, the adsorption capacity of geopolymer shows an upward trend, with the most significant improvement in the adsorption of UO 2 2+. In addition, when the Si/Al ratio reduces, the migration rate of UO 2 2+ and NO 3 − slows down. It could hinder the diffusion of ions in nanopores of geopolymer. The work could optimize the preparation of geopolymer adsorbent, and reveal the transport mechanism of uranyl nitrate in nanopore of geopolymer with different Si/Al ratios at the atomic scale. Uranyl nitrate in nanopore of geopolymer with different Si/Al ratios. [Display omitted] • Transport mechanism of uranyl nitrate in nanopore of geopolymer was studied firstly. • The effects of different Si/Al ratios on adsorption of uranyl nitrate in nanopore of geopolymer were studied by molecular dynamics simulation. • The work could optimize the preparation of geopolymer adsorbent and improve its adsorption performance. [ABSTRACT FROM AUTHOR]

The scanning electron microscope and its attached X-ray unit are valid tools for conducting surveys to determine whether or not the studied samples contain nuclear material. To verify their structure, ten solid uranyl nitrate specimens with various enrichment values (0.1 % to 1 %) were analyzed. The used samples have different numbers of hydrated water molecules; consequently, the properties of these materials in analytical chemistry and computational methods are not the same. Scanning electron microscope and energy dispersive X-ray are used in this work to visualize and analyze the sample of hexahydrate uranyl nitrate (natural 0.72 %). The specimen has been screened under optimal microscopy circumstances. In spite of the reliability of these tools, they are not accurate, particularly when carrying out complete qualitative and quantitative analysis. With the aid of the Monte Carlo code (MCNP-5), the approach presented here can resolve the limitations that tackle the microscope and X-ray testing. The suggested approach relates to the Monte Carlo calculations and X-ray elemental analysis. This relationship depends on the chemical composition of the material and was developed like software. The concentration and count rate calculation software has been established to determine the water of crystallization for uranyl nitrate samples.

The determination of free acidity and uranium in a radioactive uranyl nitrate solution inside a hot cell has to be done remotely. It generally involves the addition of complexing agents or the application of sophisticated analytical methods and modelling. To make the analyses uncomplicated, a simple acid–base conductometric titration method was developed to determine the free acidity and the uranium concentration simultaneously. Uranyl nitrate solutions containing nitric acid from 0.02 to 0.83 mmol and uranium from 0.32 to 15.90 mg per aliquot were determined by this method. The precision and accuracy of the method were found to be within ± 5%. For the titrations carried out at higher temperatures, the bias was found to be within ± 10%. [ABSTRACT FROM AUTHOR]

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A set of Pitzer parameters was obtained to accurately describe the thermodynamic properties of solutions in the H2O–UO2(NO3)2–Th(NO3)4–HNO3 system at 25°С and represent the thermodynamic properties of liquid phases in the H2O–Th(NO3)4–HNO3 subsystem in the temperature range 25–50°С. Solubility products were calculated for crystal hydrates Th(NO3)4 · 6H2O and UO2(NO3)2 · 3H2O to predict the solubilities of these compounds in those solutions over a wide concentration range. [ABSTRACT FROM AUTHOR]

A set of Pitzer interaction parameters is proposed to describe thermodynamic properties of the H2O–UO2(NO3)2–HNO3 solution within the temperature range of 15 to 50°C and ranges of concentrations of HNO3 and UO2(NO3)2 of 0 to 40 and 0 to 8 mol/kg, respectively. The experimental data on the vapor pressures of the volatile components of the system, degree of dissociation of nitric acid, and solid–liquid equilibria are used to determine these parameters. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the toxic effects of uranium on the thyroid gland and certain blood and biochemical parameters, in addition to determining the role that iron can play in reducing the toxic effects of uranium in white male rats using 24 adult white males, divided into three equal groups. The control group was given physiological saline solution in concentration ( 0.9% ), the treatment group T1 was given uranyl nitrate at a concentration of (75mg / Kg) of body weight and were given the usual diet and treatment group (T2) were given uranyl nitrate (75mg / kg) and Ferrous sulfate was also given concentrate (30mg / kg) from the diet. The results showed that the effect of uranyl nitrate was significant. The Ferrous sulfate has a significant effect in inhibiting the toxicity of uranyl nitrate used. [ABSTRACT FROM AUTHOR]

Ammonium uranyl carbonate (AUC), an intermediate material in the process of conversion of yellowcake to uranium hexafluoride, was produced by injection of an aqueous solution of ammonium carbonate (AC) into uranyl nitrate solution. The target parameter in optimization of this process was the yield of the precipitation, as morphology and size distribution of AUC play no role in its post processing to UF6. The aim of the current study was the experimental investigation of the effects of the process variables on the yield of AUC precipitation. The results showed that the flow rate and flow pattern of the injection of the AC solution, aging time, impeller speed, and temperature had little effects on the yield of AUC precipitation. On the other hand, the yield was increased by increasing the ammonium carbonate to uranyl nitrate molar ratio, ammonium carbonate concentration, and uranyl nitrate concentration. However, it decreased by increasing the molar ratio of CO32- to NH4+ ions in the ammonium carbonate solution.

Introduction: Radiochemical production is one of the richest in terms of data for analytical control, high-quality implementation of which is impossible without using type approved reference materials (RMs). Industry-specific institutes used to satisfy the demand for RMs, many of which nowadays have ceased this type of activities due to various reasons. The paper in question covers problems of metrological support in radiochemical production caused by the lack of type approved RMs.Materials and methods: Technologies used for obtaining homogeneous reference material for radiochemical production are described. Methods and measuring instruments used for certifying RMs are listed.Results: Results of developing certified reference materials at Mayak Production Association are given. Examples of codeveloping RMs of triuranium octoxide and plutonium dioxide are provided.Discussion and conclusions: Assessment of the current situation in terms of provision of type approved RMs is given. The paper provides data on availability of raw material, quality of instrument and methodological base in order to create a reference material production site at Mayak Production Association. Results of step-by-step solutions to problems of metrological assurance in radiochemical production are presented. Research prospects of developing RMs for inductively coupled plasma mass spectrometry are outlined. An outlook is given and practical proposals are formulated in the paper. The proposals in question are related to the interaction between institutes and enterprises of the field in terms of developing type approved RMs.

The thermal stability of mixtures of TBP and its solutions in diluents with uranyl nitrate (UN) at 150–200°C was evaluated. Exothermic self-accelerating oxidation processes (thermal explosions) arise in mixtures with TBP at 160–170°C. In mixtures of UN with solutions of TBP in diluents, the intensity of the exothermic processes is appreciably lower. The presence of the extractant in UN solutions fed to high-temperature operations gives rise to the hazard of the initiation of intense exothermic processes. [ABSTRACT FROM AUTHOR]

To develop strategies for incorporating transition metal taggants (Fe, Cr, and Ni) into oxide fuels and to understand how these taggant candidates persist through early fuel cycle processes, synthetic procedures are modified from established production routes to yield intentionally tagged early fuel cycle intermediates including uranyl nitrate hexahydrate (UNH, UO 2 (NO 3) 2 ·6H 2 O), uranyl peroxide tetrahydrate (studtite, UO 2 O 2 ·4H 2 O), and uranyl peroxide dihydrate (metastudtite, UO 2 O 2 ·2H 2 O). First, Fe, Cr, and Ni nitrate solutions are introduced to an aqueous solution of UNH followed by precipitation to produce tagged UNH. Then, studtite is precipitated from UNH followed by dehydration to metastudtite. Structural influences of taggant incorporation within all synthesized phases are investigated using powder X-ray diffraction (PXRD) and Raman spectroscopy to provide insight into crystallographic modifications resulting from the addition of tags to these early fuel cycle materials and elucidate the chemical form of taggants introduced at these stages. The possibility of segregation of taggant species into discrete phases within U matrices was examined using scanning electron microscopy with energy dispersive X-ray spectroscopy. Taggant concentrations in solid-phase materials were determined using inductively coupled plasma-optical emission spectroscopy. Observations from Raman spectroscopy and PXRD indicate that introducing transition metal tags during uranyl nitrate precipitation results in potential impurity phase segregation in UNH, but transition metal incorporation is suggested by results for tagged uranyl peroxide materials. Results from this study will inform strategies for optimizing taggant incorporation in UO 2. [ABSTRACT FROM AUTHOR]

Uranium (U) is a heavy metal used in military and industrial settings, with a large portion being mined from the Southwest region of the United States. Uranium has uses in energy and military weaponry, but the mining process has released U into soil and surface waters that may pose threats to human and environmental health. The majority of literature regarding U’s human health concern focuses on outcomes based on unintentional ingestion or inhalation, and limited data are available about its influence via cutaneous contact. Utilizing skin dermis cells, we evaluated U’s topical chemotoxicity. Employing soluble depleted uranium (DU) in the form of uranyl nitrate (UN), we hypothesized that in vitro exposure of UN will have cytotoxic effects on primary dermal fibroblasts by affecting cell viability and metabolic activity and, further, may delay wound healing aspects via altering cell proliferation and migration. Using environmentally relevant levels of U found in water (0.1 μM to 100 μM [UN]; 23.8–23,800 ppb [U]), we quantified cellular mitosis and migration through growth curves and in vitro scratch assays. Cells were exposed from 24 h to 144 h for a time-course evaluation of UN chemical toxicity. The effects of UN were observed at concentrations above and below the Environmental Protection Agency threshold for safe exposure limits. UN exposure resulted in a dose-dependent decrease in the viable cell count; however, it produced an increase in metabolism when corrected for the viable cells present. Furthermore, cellular proliferation, population doubling, and percent closure was hindered at levels ≥10 μM UN. Therefore, inadvertent exposure may exacerbate pre-existing skin diseases in at-risk demographics, and additionally, it may substantially interfere in cutaneous tissue repair processes.

In this study, various solid uranium oxycompounds and TiO2-supported materials based on nanocrystalline anatase TiO2 are synthesized using uranyl nitrate hexahydrate as a precursor. All uranium-contained samples are characterized using N2 adsorption, XRD, UV–vis, Raman, TEM, XPS and tested in the oxidation of a volatile organic compound under visible light of the blue region to find correlations between their physicochemical characteristics and photocatalytic activity. Both uranium oxycompounds and TiO2-supported materials are photocatalytically active and are able to completely oxidize gaseous organic compounds under visible light. If compared to the commercial visible-light TiO2 KRONOS® vlp 7000 photocatalyst used as a benchmark, solid uranium oxycompounds exhibit lower or comparable photocatalytic activity under blue light. At the same time, uranium compounds contained uranyl ion with a uranium charge state of 6+, exhibiting much higher activity than other compounds with a lower charge state of uranium. Immobilization of uranyl ions on the surface of nanocrystalline anatase TiO2 allows for substantial increase in visible-light activity. The photonic efficiency of reaction over uranyl-grafted TiO2, 12.2%, is 17 times higher than the efficiency for commercial vlp 7000 photocatalyst. Uranyl-grafted TiO2 has the potential as a visible-light photocatalyst for special areas of application where there is no strict control for use of uranium compounds (e.g., in spaceships or submarines).

A unified model based on published data and authors' experimental results was suggested for describing the extraction of An(VI) (An = U, Np, Pu, Am) from HNO3 solutions into TBP solutions of various concentrations. Parallel occurrence of several extraction reactions and of nonstoichiometric physicochemical interaction of the components is assumed. The calculated parameters of the dependence of the concentration equilibrium constants on the total TBP concentration allowed expansion of the range of extractant concentrations described by the model (from 2.7 to 100%) and reduction of the uncertainty in calculation of the HNO3 and An(VI) distribution ratios. The parameter of apparent hydration of nitrate salt cations in the aqueous phase was used for describing the salting-out effect of these salts. [ABSTRACT FROM AUTHOR]

We have measured photoluminescence spectra of uranyl nitrate (UO2(NO3)2) crystals and a UO2(NO3)2-filled opal crystal. The spectra have been compared to the corresponding photoluminescence spectrum of photonic glass. The photoluminescence spectra were excited by semiconductor light-emitting diodes, a cw laser, and repetitive laser pulses. The excitation wavelengths were located in the resonance absorption band of the uranyl compound. This has offered the possibility of measuring the photoluminescence spectrum of UO2(NO3)2 at an acquisition time of 1 ms, using the smallest possible amount of the substance (down to 10–9 g). The spectra have been obtained in the range 200–1000 nm using a fiber-optic minispectrometer. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the uranium distribution and histopathological changes in broiler organs (kidney, liver, and brain) and muscle after 7 days of contamination with high doses of uranyl nitrate hexahydrate (UN), and the protective efficiency of three different mineral adsorbents (organobentonite, organozeolite, and sepiolite). During the 7 days, the UN administration was 50 mg per day, and administration of adsorbents was 2 g per day immediately after UN. In control group where broilers received only UN, histopathological changes such as necrosis of intestinal villi, oedema, vacuolisation and abruption of epithelial cells in renal tubules, oedema and vacuolisation of the cytoplasm of hepatocytes, and dystrophic changes in the neurons of the medulla oblongata were observed. In contrast, when the adsorbents organobentonite, organozeolite, and sepiolite were administered, no histopathological changes were observed in liver and brain. The investigated adsorbents showed the highest protective effects in liver (80–92%), compared to the kidney (77–86%), brain (37–64%), and meat (31–63%). [ABSTRACT FROM AUTHOR]

We have measured photoluminescence spectra of uranyl nitrate (UO2(NO3)2) crystals and a UO2(NO3)2-filled opal crystal. The spectra have been compared to the corresponding photoluminescence spectrum of photonic glass. The photoluminescence spectra were excited by semiconductor light-emitting diodes, a cw laser, and repetitive laser pulses. The excitation wavelengths were located in the resonance absorption band of the uranyl compound. This has offered the possibility of measuring the photoluminescence spectrum of UO2(NO3)2 at an acquisition time of 1 ms, using the smallest possible amount of the substance (down to 10–9 g). The spectra have been obtained in the range 200–1000 nm using a fiber-optic minispectrometer. [ABSTRACT FROM AUTHOR]

Phase splitting of tributylphosphate (TBP)/n-dodecane organic phases resulting from the extraction of UO2(NO3)2, Th(NO3)4 and mixtures of both actinides from aqueous nitrate solutions has been investigated. Limiting organic concentrations (LOC) and metals distribution beyond third phase formation have been determined, with comparison between the cases of single metal-systems and metals mixtures. Simultaneous quantification of TBP and both metals was achieved through X-ray fluorescence (XRF) analyses. LOC studies reveal that thorium (IV) drives the third phase formation as it is the most destabilizing element in the solvent. After organic phase splitting, studies of the distributions of metals between the heavy organic phase (HOP) and the diluted organic phase (DOP) in the case of U(VI)/Th(IV) mixtures revealed that they are similar to those observed when both metals are alone in the solvent: Thorium (IV) has a strong affinity for the HOP, whereas uranium (VI) distributes both in HOP and in DOP. A supersaturation coefficient (NLOC) is proposed as a new tool to account for the data obtained in the present study. Furthermore, the approach was successfully applied to analyse available data in the literature regarding thorium (IV) distribution studies after phase splitting in various TBP-alkane solvents. Such a study beyond third phase formation paves the way for studying the mechanism involved in third phase formation, as the metal is clearly identified as the key parameter. [ABSTRACT FROM AUTHOR]

A combination of the density and Raman measurements for rapid in situ determination of uranium concentration and free acid molarity in uranyl nitrate solutions is proposed. Laboratory validation and field tests performed using a portable handheld density meter and a handheld Raman spectrometer demonstrated a feasibility of the approach in the range of uranium concentration from 50 to 426 g L−1, and free acid molarity ≤ 3 M. The combined standard uncertainties of the uranium and free acidity determination were found to be 2.4% and 5.7%, respectively. Potentials of the method in safeguards and process control applications are highlighted. [ABSTRACT FROM AUTHOR]

Uranium is a heavy metal of considerable environmental and occupational concern. It is well-known that the kidney is the major target organ of uranium exposure. Elucidating the mechanistic basis of uranium interactions is essential for monitoring the health risk. In the present study, we investigated the cellular mechanisms involved in uranyl nitrate-induced nephrotoxicity. Male Swiss albino mice were administrated with a single intraperitoneal dose of 2 and 4 mg/kg of uranyl nitrate at different time points 1, 3, 5, 7, 14, and 28 days. Uranyl nitrate intoxication-induced apoptosis in the kidney tissue was observed by TUNEL assay. To assess the proliferation, immunohistochemistry was performed using Ki67 proliferative marker followed by western blotting to confirm the involvement of key signaling molecules. The number of TUNEL positive nuclei peaked at third day after uranyl nitrate insult. The increased expression of proliferation marker Ki67 suggests the enhanced DNA repair process prominently at seventh day. Uranyl nitrate administration also resulted in activation of extracellular signal-regulated kinases (ERK), Akt, and c-Jun N-terminal kinases (JNK) expression. All these changes were found to be time-dependent. The result of the current study suggests that uranyl nitrate induces acute renal injury by activation of apoptosis through JNK pathway, while the early activation of signaling molecules Akt and ERK promotes the tubular cell proliferation and cell survival. [ABSTRACT FROM AUTHOR]

Denitration of nitric acid uranium solutions under the action of UHF radiation in ambient and reducing atmosphere in the presence of organic reductants containing amino groups (carbohydrazide, acetohydroxamic acid, aminoacetic acid, hydrazine nitrate) and without them to obtain a mixture of uranium oxides was studied. The conditions of thermal transformation of the initially formed mixture of uranium oxides into uranium dioxide powder under the action of UHF radiation were determined. The characteristics of UO2 powders meet the requirements of TU (Technical Specification) 95414–2005 to ceramic-grade powders. [ABSTRACT FROM AUTHOR]

An efficient and simple method was developed for the synthesis pyrimidine-5-carboxamides using UO2(NO3)2.6H2O catalyst under conventional and microwave irradiation. The synthesis of dihydropyrimidine using uranyl nitrate had shown many advantages such as easy work up, shorter reaction times and higher yields using acetonitrile as a solvent. The structures of the synthesized compounds were confirmed by FT-IR, 1H NMR, 13C NMR and mass spectral data. All the synthesized compounds screened for in vitro antioxidant and antibacterial activity and the results are reported. DOI: http://dx.doi.org/10.4314/bcse.v30i1.11

The use of subcritical aqueous homogenous reactors driven by accelerators presents an attractive alternative for producing 99Mo. In this method, the medical isotope production system itself is used to extract 99Mo or other radioisotopes so that there is no need to irradiate common targets. In addition, it can operate at much lower power compared to a traditional reactor to produce the same amount of 99Mo by irradiating targets. In this study, the neutronic performance and 99Mo, 89Sr, and 131I production capacity of a subcritical aqueous homogenous reactor fueled with low-enriched uranyl nitrate was evaluated using the MCNPX code. A proton accelerator with a maximum 30-MeV accelerating power was used to run the subcritical core. The computational results indicate a good potential for the modeled system to produce the radioisotopes under completely safe conditions because of the high negative reactivity coefficients of the modeled core. The results show that application of an optimized beam window material can increase the fission power of the aqueous nitrate fuel up to 80%. This accelerator-based procedure using low enriched uranium nitrate fuel to produce radioisotopes presents a potentially competitive alternative in comparison with the reactor-based or other accelerator-based methods. This system produces ∼1,500 Ci/wk (∼325 6-day Ci) of 99Mo at the end of a cycle.