The effect of high power ultrasound on an aqueous suspension of graphite

Ultrasound treatment was used to study the decrease of the granulometry of graphite, due to the cavitation, which allows the erosion by separating grains. At a smaller scale, cavitation bubble implosion tears apart graphite sheets as shown by HRTEM, while HO and H radicals produced from water sonolysis, generate oxidative and reductive reactions on these sheet fragments. Such reactions form smaller species, e.g. dissolved organic matter. The methodology proposed is very sensitive to unambiguously identifying the in situ composition of organic compounds in water. The use of the atmospheric pressure chemical ionization (APCI) Fourier transform mass spectrometry (FTMS) technique minimizes the perturbation of the organic composition and does not require chemical treatment for analysis. The structural features observed in the narrow range (m/z < 300) were mainly aromatic compounds (phenol, benzene, toluene, xylene, benzenediazonium, etc.), C4-C6 alkenes and C2-C10 carboxylic acids. Synthesis of small compounds from graphite sonication has never been reported and will probably be helpful to understand the mechanisms involved in high energy radical reactions

Quantitative description and local structures of trivalent metal ions Eu(III) and Cm(III) complexed with polyacrylic acid

The trivalent metal ion (M(III) = Cm, Eu)/polyacrylic acid (PAA) system was studied in the pH range between 3 and 5.5 for a molar PAA-to-metal ratio above 1. The interaction was studied for a wide range of PAA (0.05 mg L−1–50 g L−1) and metal ion concentrations (2×10−9–10−3 M). This work aimed at 3 goals (i) to determine the stoichiometry of M(III)–PAA complexes, (ii) to determine the number of complexed species and the local environment of the metal ion, and (iii) to quantify the reaction processes. Asymmetric flow-field-flow fractionation (AsFlFFF) coupled to ICP-MS evidenced that size distributions of Eu–PAA complexes and PAA were identical, suggesting that Eu bound to only one PAA chain. Time-resolved laser fluorescence spectroscopy (TRLFS) measurements performed with Eu and Cm showed a continuous shift of the spectra with increasing pH. The environment of complexed metal ions obviously changes with pH. Most probably, spectral variations arose from conformational changes within the M(III)–PAA complex due to pH variation. Complexation data describing the distribution of complexed and free metal ion were measured with Cm by TRLFS. They could be quantitatively described in the whole pH-range studied by considering the existence of only a single complexed species. This indicates that the slight changes in M(III) speciation with pH observed at the molecular level do not significantly affect the intrinsic binding constant. The interaction constant obtained from the modelling must be considered as a mean interaction constant

Characterization of At- species in simple and biological media by high performance anion exchange chromatography coupled to gamma detector.

Astatine is a rare radioelement belonging to the halogen group. Considering the trace amounts of astatine produced in cyclotrons, its chemistry cannot be evaluated by spectroscopic tools. Analytical tools, provided that they are coupled with a radioactive detection system, may be an alternative way to study its chemistry. In this research work, High Performance Anion Exchange Chromatography (HPAEC) coupled to a gamma detector (γ) was used to evaluate astatine species under reducing conditions. Also, to strengthen the reliability of the experiments, a quantitative analysis using a reactive transport model has been done. The results confirm the existence of one species bearing one negative charge in the pH range 27.5. With respect to the other halogens, its behavior indicates the existence of negative ion, astatide At-. The methodology was successfully applied to the speciation of the astatine in human serum. Under fixed experimental conditions (pH 7.47.5 and redox potential of 250 mV) astatine exists mainly as astatide At- and does not interact with the major serum components. Also, the method might be useful for the in vitro stability assessment of 211At-labelled molecules potentially applicable in nuclear medicine

Modeling Metal–Particle Interactions With an Emphasis on Natural Organic Matter

Numerous models exist for predicting metal interactions in the environment, but few have been validated with field observations. Modeling the binding of metal ions and actinides to natural particles of various origins remains a challenging task. The use of models to understand the speciation and distribution of metals in the environment is essential for predicting metal bioavailability. In this article, we discuss the primary metal–particle interaction models and their limits, with an emphasis on natural organic matter (NOM). These models have varying levels of complexity, but we discuss only those based on parameters that are independent of environmental conditions. We also discuss the application of such models to field predictions

Etat de la réglementation et des pratiques sur les contrôles radiologiques des déchets ménagers dans différents états membres de la communauté européenne

Programme RECORD 02-0127/1A, Rapport fina

Exploration of the fundamental chemistries of Ru for establishing 103-Ru/103m-Rh Auger generator

International audienc

Optimization of the Separating Resin for establishing a 103-Ru/ 103m-Rh Generator

International audienceIntroduction: Auger emitters are investigated for their application in radiotherapy. Among them, 103mRh can be produced from 103Ru.1 The most challenging task is to reach an effective separation between the radionuclides concerned. Separations of these two elements by liquid-liquid extraction2 or by distillation3 are already known. Nevertheless, the use of a chromatographic-type generator (103Ru/103mRh) would be more practical for widespread research use, and in particular in nuclear medicine services. The main objective is to find an ionic exchange resin able to separate these two elements efficiently. Methods: Several resins (Dowex 1x8 Cl-, Resin 1 Triskem®, Resin 2 Triskem®) have been considered to evaluate their capacity to separate Ru and Rh. Preliminary tests have been achieved. The conditions are batch experiments, [Ru]=[Rh]~10-5M. The elements were analyzed by ICP-OES or ICP-MS (initial and final concentrations) in order to establish the Kd values on the different resins tested. For the most promising resin, additional studies (influence of the raw material, repeatability, reproducibility) and column tests have been conducted. Results: Based on the preliminary results, Resin 2 Triskem® seems to be the most suitable candidate for Ru/Rh separation. More than 90% of Ru initially introduced is retained on the resin, and no Rh is retained. Age of Ru solutions has an impact on the speciation of Ruthenium and its retention on the resin.Discussion: Resin 2 Triskem® appears to be able to be used in the chromatographic-type generator (103Ru/103mRh). More studies need to be conducted to certify its potential, especially Ru breakthrough evaluation. (1)Filosofov and al. Potent Candidates for Targeted Auger Therapy: Production and Radiochemical Considerations. Nuclear Medicine and Biology 2021, 94–95, 1–19. (2)Al-Bazi and al. Extraction of Ruthenium Thiocyanate and Its Separation from Rhodium by Polyurethane Foam. Talanta 1984, 31 (3), 189–193.(3)Kurbatov and al. Isolation of Carrier Free Rhodium from Ruthenium Targets. Journal of Inorganic and Nuclear Chemistry 1961, 18, 19–23

Étude des générateurs in vivo 212Pb / 212Bi et 230U / 226Th pour la radiothérapie ciblée

La radiothérapie ciblée est une thérapie anticancéreuse particulièrement innovante. Elle repose sur l utilisation d un vecteur spécifique de la cellule cible à détruire, radiomarqué par un élément radioactif émetteur de particules. Le 212Bi et le 226Th sont deux candidats particulièrement intéressants. Tous deux ont été étudiés, au cours de ce travail, sont la forme des générateurs in vivo 212Pb / Bi212 et 230U / 226Th. Deux méthodes ont été étudiées pour envisager leur vectorisation. Une approche par chélation a été envisagée pour les deux générateurs. Elle consiste à fixer sur le vecteur un deuxième ligand qui, dans des conditions biologiques, doit être en mesure de recomplexer le radioisotope fils, suite à la décroissance radioactive. Le DTPA, présentant de fortes constantes de complexation pour le Bi(III) et le Th(IV) a été testé pour les deux générateurs. Evalué expérimentalement et validé par modélisation, le DTPA s est avéré inefficace pour la complexation du Bi(III) et du Th(IV) dans le sérum humain, le facteur limitant étant un problème de sélectivité du DTPA entre le radioisotope et le Fe(II) présent dans le sérum. Une approche par encapsulation dans des liposomes a donc été envisagée. Cette méthode est uniquement envisageable pour le générateur 212Pb / Bi. L encapsulation de 2-3 Pb par liposome a été réalisée avec un rendement de 75%. Des études de stabilité in vitro, réalisées à l aide du couplage AF4/, ont montré une bonne rétention des radioisotopes père et fils dans le compartiment interne des liposomesTargeted therapy is a promising cancer therapy. The principle is to use tumor-specific vectors labeled with particles emitters. 212Bi and Th are two promising candidates. In the present work, they were studied as in vivo226 generators 212Pb / Bi212 and 230U / 226Th. Two methods were studied for allowing their vectorization. Chelation approach was first considered for both generators. It consists to fix on the vector a second ligand, which in biological conditions, must be able to complex the daughter radionuclide. DTPA, with strong complexation constants for Bi(III) and Th(IV), was tested for both generators. DTPA appears to be inefficient for complexing Bi(III) and Th(IV) in human serum, the limiting factor being a problem of selectivity of DTPA between the radioisotope and the Fe(II) present in serum. This was shown both experimentally and theoretically. An encapsulation approach has been also considered. This method is only possible for the Pb212 / 212Bi generator. The efficient entrapment of about 2-3 Pb atoms per liposome was performed with a yield of 75%. In vitro stability studies, performed with the coupling AF4/, showed good retention of the mother and daughters radionuclides in the internal compartment of liposomesNANTES-BU Sciences (441092104) / SudocNANTES-ENS Mines (441092314) / SudocSudocFranceF

Speciation of Ru through A4F-MALS, Spectrophotometry UV-Visible and LDI-TOF for a 103-Ru/103m-Rh generator

International audienceObjectives: Ruthenium is considered to be an interesting element for establishing a 103Ru/103mRh generator for Auger therapy. In radiochemical processes, Ru may be present as Ru(II), (III), (IV), (VI), (VII), or (VIII), with Ru (III) and Ru (IV) the most numerous and stable compounds [1, 2]. But a chloride solution initially contains both Ru(III) and Ru(IV) species [1]. Ru species chemical behaviors are strongly pH dependent, leading to polynuclear complexes. This tendency to form polynuclear complexes linked by oxide and hydroxide bounds is most prominent for the oxidation states +III and +IV [3]. Additionally, colloidal ruthenium hydroxides are formed by the hydrolysis of Ru(III) and Ru(IV) compounds. These polynuclear, polymeric and colloidal species are not desirable for establishing a well-controlled chromatographic 103Ru/103mRh generator.Methods: It is of utmost importance to avoid the formation of colloidal species for the use of a 103Ru/103mRh generator for Auger therapy. Asymmetrical Flow-Field- Flow Fractionation (AF4) has been be used to analyze different Ru(IV) solutions in different HCl concentrations to check the presence / absence of Ru colloids in order to establish suitable HCl conditions for elution, i.e. keeping monomeric Ru(IV) on the resin when avoiding Ru colloids formation. The speciation of Ru was carried out by Asymmetrical Flow Field-Flow Fractionation (AF4) coupled to a Multi-Angle Light Scattering (MALS) detector. Results: The presence of ruthenium colloid in aqueous solution was evidenced with a polymodal and polydisperse profile. Ruthenium colloids formation appears before a precipitation within RuO2, visible at pH 2 and pH 4. Ruthenium colloids observed in the supernatant seems to be more stable at pH 4 than at pH 2 since no colloid has been observed at pH 2 either by MALS or by UV. These data lead to assume that it is possible to make generator in acidic pH conditions because in this case, all the species are in solution, and no colloids are formed 1. Lawrence MAW, Bullock JL, Holder AA (2017) Basic Coordination Chemistry of Ruthenium. In: Browne WR, Holder AA, Lawrence MA, et al (eds) Ruthenium Complexes. Wiley, Germany2. Epperson CE (1975) Generator Separation of Ru-103/Rh-103m. University of Perdue, PhD Thesis3. Niedrach LW, Tevebaugh AD (1951) The Polarography of Ruthenium (IV) in Perchloric Acid Solutions. J Am Chem Soc 73:2835–2837. https://doi.org/10.1021/ja01150a11

Recent progress in ruthenium chemistry for establishing a 103Ru/103mRh generator for Auger therapy

International audienceThe most challenging task for establishing a Ru-103/Rh-103m generator for Auger therapy, is to reach an effective separation between the two radionuclides because of the highly unpredictable, very complicated and poorly understood chemistry. In HCl, this work was able to evidence the formation of Ru colloids. It has been evidenced that the starting material of Ru, time and temperature have a strong influence on Ru speciation, but no polynuclear species of ruthenium-chloride was observed. This work has showed that it is fully possible to control the speciation of ruthenium, especially Ru(IV), within a mononuclear species; that is a huge step forward compared to literature