Experimental and Theoretical X-ray Absorption Near Edge Structure Study of UO Systems at the U L Edge.

Uranium forms a large number of oxides and its electronic state in them is of great fundamental interest. We employ X-ray absorption spectroscopy at the U L edge to differentiate between mixed oxide phases in uranium compounds. By combining experimental XANES spectra with theoretical modeling using the FEFF code, we analyze five uranium oxides: UO, UO, UO, UO, and UO.

Unexpected nanoscale CeO structural transformations induced by ecologically relevant phosphate species.

In the present study, the dissolution and microstructural transformation of CeO nanoparticles (NPs) in a phosphate-containing milieu were investigated. The dissolution behaviour of 2 nm and 5 nm CeO NPs in phosphate buffer solutions was found to differ markedly from that observed in 0.01 M NaClO.

Carbon materials for effective purification of aqueous solutions from tributyl phosphate.

This study investigates various sorbents for the effective sorption of dissolved organic substances, using tributyl phosphate (TBP) as a model compound. TBP is one of the most commonly used extractants in the nuclear industry. Four different carbon materials with high specific surface areas (2000-3000 m g) were selected for evaluation.

Assessing the biocompatibility and stability of CeO nanoparticle conjugates with azacrowns for use as radiopharmaceuticals.

The application of nanoparticles is promising for the purposes of nuclear medicine due to the possibilities of using them as vectors and transporters of radionuclides. In this study, we have successfully synthesised conjugates of CeO nanoparticles and azacrown ligands. Then, the radiolabelling conditions with radionuclides Zn, Sc and Bi were selected and the kinetic stability of the complexes in biologically significant media was evaluated.

Trace Elements in Medicinal Metallomics.

This analytical mini-review focuses on the effects of trace elements, which includes Cu, Mn, Zn, and Se, as well as some rarer microelements, on the regulation of oxidative stress in the body and of certain diseases associated with it. Synergism and competition between certain microelements have been considered a hot topic in the applied molecular pharmacology of these specific bio-effects. Some ideas for further possible directions of research are expressed.

Going deeper into plutonium sorption affected by redox.

Sorption of Pu(VI) onto synthesized goethite under oxidizing and normal conditions was investigated, which revealed its pH dependence on different solid/liquid ratios. Pu speciation upon sorption on the solid phase was characterized via extended X-ray absorption fine structure (EXAFS) spectroscopy, while that in solution was assessed using ultraviolet-visible (UV-Vis) spectroscopy and liquid-liquid extraction. The obtained results demonstrate differences in plutonium behavior in the studied systems.

Level, distribution and sources of Np, Pu and Am isotopes in Peter the Great Bay of Japan sea.

Transuranium elements such as Np, Pu and Am, are considered to be the most important radioactive elements in view of their biological toxicity and environmental impact. Concentrations of Np, Pu isotopes and Am in two sediment cores collected from Peter the Great Bay of Japan Sea were determined using radiochemical separation combined with inductively coupled plasma mass spectrometry (ICP-MS) measurement. The Pu and Am concentrations in all sediment samples range from 0.

Pyridine Diphosphonate Ligand for Stabilization of Tetravalent Uranium and Neptunium in Aqueous Medium under Aerobic Conditions.

Though uranium is usually present in its +6 oxidation state (as uranyl ion) in aqueous solutions, its conversion to oxidation states such as +4 or +5 is a challenging task. Electrochemical reduction and axial oxo activation are the preferred methods to get stable unusual oxidation states of uranium in an aqueous medium. In previous studies, dicarboxylic acid has been used to stabilize UO in aqueous alkaline solutions.

Kinetic features of solvent extraction by N,O-donor ligands of f-elements: a comparative study of diamides based on 1,10-phenanthroline and 2,2'-bipyridine.

A variant of microfluidic setup design for the study of extraction kinetics has been proposed. Mass transfer constants for Am(III) and Eu(III) and observed rate constants were obtained for N-,O-donor ligands featuring phenanthroline and bipyridyl cores. The possibility of determining rate constants for cations independently of each other makes it possible to observe the kinetic effect of separation.

Formation of Neptunium(V) Carbonates: Examining the Forceful Influence of Alkali and Alkaline Earth Cations.

Herein, neptunium(V) carbonates containing sodium or potassium cations were synthesized via chemical precipitation. Various techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetry combined with differential scanning calorimetry, X-ray diffraction, and X-ray absorption spectroscopy were used to analyze the microstructures and elemental compositions of these samples. The crystal structures of hydrated NaNpOCO·3HO (1, = 4.

Laboratory-based X-ray spectrometer for actinide science.

X-ray absorption and emission spectroscopies nowadays are advanced characterization methods for fundamental and applied actinide research. One of the advantages of these methods is to reveal slight changes in the structural and electronic properties of radionuclides. The experiments are generally carried out at synchrotrons.

Sensing and extraction of hazardous metals by di-phosphonates of heterocycles: a combined experimental and theoretical study.

In this study, pyridine and phenanthroline diphosphonate ligands were investigated for the first time from the context of solvent extraction and potentiometric sensing of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) cations. The extraction efficiency under the same conditions for phenanthroline-diphosphonates is considerably higher than that for pyridine ligands. At the same time, the pyridine-diphosphonates show pronounced selectivity towards lead in this metal series.

Insights into Actinium Complexes with Tetraacetates─AcBATA versus AcDOTA: Thermodynamic, Structural, and Labeling Properties.

In the current research, we conducted a comparative study of the Ac complex with HDOTA and HBATA. The stability constants of the [AcBATA] and [AcDOTA] complexes were studied directly by extraction methods. We discovered that the thermodynamic properties of the [AcBATA] complex are superior to those of [AcDOTA].

The features of Cs sorption onto peaty-podzolic-gleyic soil.

This article studies sorption regularities and estimates the strength of Cs fixation by various soil horizons in peaty-podzolic-gleyic soils under a model experiment. The interaction time varied from 1 week to 3 months while Cs concentration varied from trace to micromolar concentrations. To understand the interaction mechanisms of cesium with individual soil components, we used the method of sequential removal of organic matter and non-silicate iron compounds from the soil before the sorption experiment.

Super-oxidized "activated graphene" as 3D analogue of defect graphene oxide: Oxidation degree vs U(VI) sorption.

Porous carbons are not favorable for sorption of heavy metals and radionuclides due to absence of suitable binding sites. In this study we explored the limits for surface oxidation of "activated graphene" (AG), porous carbon material with the specific surface area of ∼2700 m/g produced by activation of reduced graphene oxide (GO). Set of "Super-Oxidized Activated Graphene" (SOAG) materials with high abundance of carboxylic groups on the surface were produced using "soft" oxidation.

Oxidation and Nanoparticle Formation during Ce(III) Sorption onto Minerals.

The sorption of Ce(III) on three abundant environmental minerals (goethite, anatase, and birnessite) was investigated. Batch sorption experiments using a radioactive Ce tracer were performed to investigate the key features of the sorption process. Differences in sorption kinetics and changes in oxidation states were found in the case of the sorption of Ce(III) on birnessite compared to that on other minerals.

Uranium oxides structural transformation in human body liquids.

Uranium oxide microparticles ingestion is one of the potential sources of internal radiation doses to the humans at accidental or undesirable releases of radioactive materials. It is important to predict the obtained dose and possible biological effect of these microparticles by studying uranium oxides transformations in case of their ingestion or inhalation. Using a combination of methods, a complex examination of structural changes of uranium oxides in the range from UO to UO, UO and UO as well as before and after exposure of uranium oxides in simulated biological fluids: gastro-intestinal and lung-was carried out.

Novel candidate theranostic radiopharmaceutical based on strontium hexaferrite nanoparticles conjugated with azacrown ligand.

In this article, we report to the best of our knowledge the first modification of NPs with ligands for combined radiopharmaceuticals. Nanoparticles with suitable magnetic properties can be used both for diagnostics as a contrast for MRI and for therapy, including the insufficiently studied magneto-mechanical therapy. Strontium hexaferrite is one of the few hard-magnetic materials for which stable biocompatible colloidal solutions can be obtained.

CeO-Azacrown Conjugate as a Nanoplatform for Combined Radiopharmaceuticals.

This study is one of the first attempts to assess CeO nanoparticles as a nanoplatform for radiopharmaceuticals with radionuclides. The process of functionalization using a bifunctional azacrown ligand is described, and the resulting conjugates are characterized by IR and Raman spectroscopy. Their complexes with Bi show a high stability in medically relevant media, thus encouraging the further study of these conjugates in vivo as potential combined radiopharmaceuticals.

Solvation-Anionic Exchange Mechanism of Solvent Extraction: Enhanced U(VI) Uptake by Tetradentate Phenanthroline Ligands.

Phenanthroline diamides () demonstrated a unique ability to extract uranium from nitric acid solutions into a polar organic solvent forming complexes of 1:2 stoichiometry as tight ion pairs {[UONO][UO(NO)]} by a novel extraction mechanism, which is a combination of two already well-known mechanisms: solvation and ion-pair anion exchange. A UV-vis study was used to confirm the formation of such complexes directly in the organic phase. Moreover, chemical synthesis and single crystal growth were performed to confirm unambiguously the structure of the complexes in the solid state.

Pyridine-di-phosphonates as chelators for trivalent f-elements: kinetics, thermodynamic and interfacial study of Am(III)/Eu(III) solvent extraction.

The fractionation of high-level radioactive waste from nuclear power plants simplifies the handling of its components, and facilitates the reduction of radiotoxic effects on the environment. The search and study of new ligands for solvent extraction, as one of the methods in fractionation, remains a complex and important research task. In this work, four pyridine diphosphonate ligands were synthesized.

Novel Hybrid Benzoazacrown Ligand as a Chelator for Copper and Lead Cations: What Difference Does Pyridine Make.

A synthetic procedure for the synthesis of azacrown ethers with a combination of pendant arms has been developed and the synthesized ligand, characterized by various techniques, was studied. The prepared benzoazacrown ether with hybrid pendant arms and its complexes with copper and lead cations were studied in terms of biomedical applications. Similarly to a fully acetate analog, the new one binds both cations with close stability constants, despite the decrease in both constants.

First Trifluoromethylated Phenanthrolinediamides: Synthesis, Structure, Stereodynamics and Complexation with Ln(III).

The first examples of 1,10-phenanthroline-2,9-diamides bearing CF-groups on the side amide substituents were synthesized. Due to stereoisomerism and amide rotation, such complexes have complicated behavior in solutions. Using advanced NMR techniques and X-ray analysis, their structures were completely elucidated.

To form or not to form: PuO nanoparticles at acidic pH.

The aim of this study is to synthesize PuO nanoparticles (NPs) at low pH values and characterize the materials using laboratory and synchrotron-based methods. Properties of the PuO NPs formed under acidic conditions (pH 1-4) are explored here at the atomic scale. High-resolution transmission electron microscopy (HRTEM) is applied to characterize the crystallinity, morphology and size of the particles.

From EXAFS of reference compounds to U(VI) speciation in contaminated environments.

Understanding the speciation of technogenic uranium in natural systems is crucial for estimating U migration and bioavailability and for developing remediation strategies for contaminated territories. Reference EXAFS data of model laboratory-prepared uranium compounds (`standards') are necessary to analyze U-contaminated samples from nuclear legacy sites. To minimize errors associated with measurements on different synchrotrons, it is important not only to compare data obtained on environmentally contaminated samples with the literature but also with `standards' collected at the same beamline.