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International audience; We report on the crystallite growth of nanometric NpO2 and UO2 powders. The AnO2 nanoparticles (An = U and Np) were synthesized by hydrothermal decomposition of the corresponding actinide(IV) oxalates. NpO2 powder was isothermally annealed between 950 °C and 1150 °C and UO2 between 650 °C and 1000 °C. The crystallite growth was then followed by high-temperature X-ray diffraction (HT-XRD). The activation energies for the growth of crystallites of UO2 and NpO2 were determined to be 264(26) kJ mol−1 and 442(32) kJ mol−1, respectively, with a growth exponent n = 4. The value of the exponent n and the low activation energy suggest that the crystalline growth is rate-controlled by the mobility of the pores, which migrate by atomic diffusion along the pore surfaces. We could thus estimate the cation self-diffusion coefficient along the surface in UO2, NpO2 and PuO2. While data for surface diffusion coefficients for NpO2 and PuO2 are lacking in the literature, the comparison with literature data for UO2 supports further the hypothesis of a surface diffusion controlled growth mechanism.

In view of safe management of the nuclear wastes, a sound knowledge of the atomic-scale properties of U1-xMxO2+y nanoparticles is essential. In particular, their cation valences and oxygen stoichiometries are of great interest as these properties drive their diffusion and migration behaviors into the environment. Here, we present an in-depth study of U1-xCexO2+y, over the full compositional domain, by combining X-ray diffraction and high-energy resolution fluorescence detection X-ray absorption near-edge structure. We show, on one hand, the coexistence of UIV, UV, and UVI and, on the other hand, that the fluorite structure is maintained despite this charge distribution.

This paper details the first dedicated production of homogeneous nanocrystalline particles of mixed actinide oxide solid solutions containing americium. The target compositions were U

Neptunium was the first actinide element to be artificially synthesized, yet, compared with its more famous neighbours uranium and plutonium, is less conspicuously studied. Most neptunium chemistry involves the neptunyl di(oxo)-motif, and transuranic compounds with one metal–ligand multiple bond are rare, being found only in extended-structure oxide, fluoride or oxyhalide materials. These combinations stabilize the required high oxidation states, which are otherwise challenging to realize for transuranic ions. Here we report the synthesis, isolation and characterization of a stable molecular neptunium(V)–mono(oxo) triamidoamine complex. We describe a strong Np≡O triple bond with dominant 5f-orbital contributions and σ u > π u energy ordering, akin to terminal uranium-nitrides and di(oxo)-actinyls, but not the uranium–mono(oxo) triple bonds or other actinide multiple bonds reported so far. This work demonstrates that molecular high-oxidation-state transuranic complexes with a single metal–ligand bond can be stabilized and studied in isolation. [Figure not available: see fulltext.]

The synthesis of three complex series of the form [AnCl2(salen)(Pyx)2] (H2salen=N,N′‐bis(salicylidene)ethylenediamine; Pyx=pyridine, 4‐methylpyridine, 3,5‐dimethylpyridine) with tetravalent early actinides (An=Th, U, Np, Pu) is reported with the goal to elucidate the affinity of these heavy elements for small neutral N‐donor molecules. Structure determination by single‐crystal XRD and characterization of bulk powders with infrared spectroscopy reveals isostructurality within each respective series and the same complex conformation in all reported structures. Although the trend of interatomic distances for An−Cl and An−N (imine nitrogen of salen or pyridyl nitrogen of Pyx) was found to reflect an ionic behavior, the trend of the An−O distances can only be described with additional covalent interactions for all elements heavier than thorium. All experimental results are supported by quantum chemical calculations, which confirm the mostly ionic character in the An−N and An−Cl bonds, as well as the highest degree of covalency of the An−O bonds. Structurally, the calculations indicate just minor electronic or steric effects of the additional Pyx substituents on the complex properties., Th–PuIV salen complexes: A series of monosalen complex with Th–PuIV has been synthesized and characterized in the solid state and with quantum chemical (QC) calculations. They reveal the salen's potential to provide a fixed binding pocket to AnIV, allowing a facile exchange of pyridine‐based solvents in the labile positions. Differences in binding strength explain the findings: all AnIV−N are of mostly ionic nature but AnIV−O have a significant covalent contribution.

Intrinsic properties of a compound (e.g., electronic structure, crystallographic structure, optical and magnetic properties) define notably its chemical and physical behavior. In the case of nanomaterials, these fundamental properties depend on the occurrence of quantum mechanical size effects and on the considerable increase of the surface to bulk ratio. Here, we explore the size dependence of both crystal and electronic properties of CeO2 nanoparticles (NPs) with different sizes by state-of-the art spectroscopic techniques. X-ray diffraction, X-ray photoelectron spectroscopy, and high-energy resolution fluorescence-detection hard X-ray absorption near-edge structure (HERFD-XANES) spectroscopy demonstrate that the as-synthesized NPs crystallize in the fluorite structure and they are predominantly composed of CeIV ions. The strong dependence of the lattice parameter with the NPs size was attributed to the presence of adsorbed species at the NPs surface thanks to Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. In addition, the size dependence of the t2g states in the Ce LIII XANES spectra was experimentally observed by HERFD-XANES and confirmed by theoretical calculations., Comment: Inorganic Chemistry (2020)

A series of tetradentate N2O2-type Schiff base complexes with tetravalent 4f- and 5f-block metals, [M(salpn)2] (H2salpn = N,N′-disalicylidene-1,3-diaminopropane; M = Ce, Th, U, Np, and Pu), were prepared to systematically investigate their solid state structure, and their complexation behaviour in solution with the goal to investigate the subtle differences between 4f- and 5f-elements. X-ray diffraction revealed that all investigated metal cations form [M(salpn)2] complexes. All the complexes show the same ligand arrangement with meridional conformation, amongst which only Ce(IV) exhibits unique behaviour upon crystallisation. [Ce(salpn)2] crystallises in two less symmetric systems (P or P21/n), whilst all the other [M(salpn)2] crystallise in a more symmetric orthorhombic system (Pban). Quantum chemical calculations suggest that the observed structural peculiarity of Ce(IV) stems from the geometrical flexibility due to the more “ionic” nature of bonds to the 4f element. 1H NMR measurements revealed that [M(salpn)2] forms two different species in solution with and without an additional solvent molecule, where the relative distribution of the two species depends mainly on the ionic radius of the metal centre. Again, Ce(IV) behaves differently from the tetravalent actinides with a higher ratio of the solvent-molecule-coordinated species than the ratio expected from its ionic radius. Hence, this study is successful in observing subtle differences between 4f- (i.e. Ce) and 5f-elements (actinides; Th, U, Np, and Pu) both in the solid state and in solution on an analytically distinguishable level, and in relating the observed subtle differences to their electronic structure.

In view of safe management of the nuclear wastes, a sound knowledge of the atomic-scale properties of U

Background Immune tolerance induction (ITI) with repeated factor VIII (FVIII) administration is the only strategy proven to eradicate inhibitors. The observational ITI study is evaluating ITI with a range of FVIII products. Methods This subgroup analysis reports prospective interim data for patients treated with a plasma-derived, von Willebrand factor-stabilized FVIII concentrate (pdFVIII/VWF, octanate). Complete success (CS) of ITI required achievement of three criteria: inhibitor titer Results One-hundred prospectively enrolled patients were included in the analysis; 91 had poor prognosis factors for ITI success. The mean (standard deviation) daily ITI dose was 116.4 (61.1) IU FVIII/kg in 14 low responders (< 5 BU/mL) and 173.7 (112.0) IU FVIII/kg in 86 high responders (≥ 5 BU/mL). Inhibitor titers Conclusions ITI with pdFVIII/VWF led to rapid eradication of FVIII inhibitors, normalization of FVIII pharmacokinetics in the majority of patients, and a significant reduction in bleeding rates.

Copper(I) complexes of the tripodal, tetradentate, aliphatic ligands Me3tren (Me3tren = tris-(2-methylaminoethyl)amine), Isoprop3tren (Isoprop3tren = tris-(2-isopropylaminoethyl)amine) and Me3isoprop3tren (Me3isoprop3tren = tris-(2-isopropylmethylaminoethyl)amine) of the Tren-family (Tren = tris(2-aminoethyl)amine) were prepared and structurally characterized. Furthermore, they were reacted in solution at low temperatures with dioxygen. All complexes formed a short-lived superoxido intermediate complex that could be observed using low temperature stopped-flow techniques prior to consecutive reactions. However, the superoxido complexes were too reactive to allow isolation and full characterization in contrast to previous work.

Kinetic measurements on the grain growth of PuO2 nano-crystals are presented. On the basis of isothermal XRD measurements at temperatures of 820 °C, 900 °C, 1000 °C, and 1100 °C the activation energy for the crystallite growth of PuO2 nanopowder is determined as 351(5) kJ mol−1 in the temperature range from 820 to 1000 °C. Modelling shows that in this T range growth happens likely through surface diffusion.

Recent developments and results from the organometallic chemistry of the actinides are reviewed. In the last one and a half years the structural data of about 15 organometallic complexes of transuranium actinides (Np or Pu) have been published, all involving π‐ligands in the coordination sphere of the metal ion. On the basis of these data, a comparison of these molecules is presented. Depending on the steric demands of the ligands, effects like the actinide contraction seem to be stronger or weaker in the structural features. This indicates that the interplay between the actinide ion and the π‐ligand is rather flexible, enabling the formation of stable bonds over a broad range of actinide ion oxidation states.

Neptunium was the first actinide element to be artificially synthesized, yet, compared with its more famous neighbours uranium and plutonium, is less conspicuously studied. Most neptunium chemistry involves the neptunyl di(oxo)-motif, and transuranic compounds with one metal-ligand multiple bond are rare, being found only in extended-structure oxide, fluoride or oxyhalide materials. These combinations stabilize the required high oxidation states, which are otherwise challenging to realize for transuranic ions. Here we report the synthesis, isolation and characterization of a stable molecular neptunium(V)-mono(oxo) triamidoamine complex. We describe a strong Np≡O triple bond with dominant 5f-orbital contributions and σ

Introduction FVIII inhibitor development is the most serious contemporary treatment complication in haemophilia A, particularly in previously untreated patients (PUPs). No inhibitors developed in clinical trials in previously treated patients treated with simoctocog alfa (Nuwiq), a fourth-generation recombinant FVIII produced in a human cell line. Methods The NuProtect study investigated the immunogenicity of simoctocog alfa in PUPs. NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. PUPs with severe haemophilia A (FVIII:C Results A total of 108 PUPs with a median age at first treatment of 12.0 months (interquartile range: 8.0–23.5) were treated with simoctocog alfa. F8 mutation type was known for 102 patients (94.4%) of whom 90 (88.2%) had null F8 mutations and 12 (11.8%) had non-null mutations. Of 105 PUPs evaluable for inhibitor development, 28 (26.7%) developed inhibitors; 17 high titre (16.2%) and 11 low titre (10.5%). No PUPs with non-null F8 mutations developed inhibitors. Conclusion In the NuProtect study, the rate of inhibitor development in PUPs with severe haemophilia A treated with simoctocog alfa was lower than the rate reported for hamster-cell-derived recombinant factor VIII products in other recent clinical trials. No inhibitors were reported in PUPs with non-null F8 mutations.

Three different Spark Plasma Sintering (SPS) treatments were applied to highly sinteractive, near-stoichiometric UO2.04 nanocrystalline (5 nm) powders produced by U(IV) oxalate hydrothermal decomposition at 170 °C. The sintering conditions for reaching 95 % Theoretical Density (TD) in regular SPS, high pressure SPS (HP-SPS), and, for the first time, two-step SPS (2S-SPS), were found. Densification to 95 % TD was achieved at 1000 °C in regular SPS (70 MPa applied pressure), 660 °C in HP-SPS (500 MPa), and 650-550 °C in 2S-SPS (70 MPa). With the goal of minimising the grain growth during densification, the sintering treatments were optimised to favour densification over coarsening, and the final microstructures thus obtained are compared. Otherwise identical, stochiometric UO2 samples of different grain sizes, ranging from 3.08 μm to 163 nm, were produced. Room-temperature oxidation of the powders could not be avoided due to their nanometric dimensions, and a final annealing treatment was designed to reduce hyper stoichiometric samples to UO2.00.

A series of tetradentate N2O2-type Schiff base complexes with tetravalent 4f- and 5f-block metals, [M(salpn)2] (H2salpn = N,N'-disalicylidene-1,3-diaminopropane; M = Ce, Th, U, Np, and Pu), were prepared to systematically investigate their solid state structure, and their complexation behaviour in solution with the goal to investigate the subtle differences between 4f- and 5f-elements. X-ray diffraction revealed that all investigated metal cations form [M(salpn)2] complexes. All the complexes show the same ligand arrangement with meridional conformation, amongst which only Ce(iv) exhibits unique behaviour upon crystallisation. [Ce(salpn)2] crystallises in two less symmetric systems (P1[combining macron] or P21/n), whilst all the other [M(salpn)2] crystallise in a more symmetric orthorhombic system (Pban). Quantum chemical calculations suggest that the observed structural peculiarity of Ce(iv) stems from the geometrical flexibility due to the more "ionic" nature of bonds to the 4f element. 1H NMR measurements revealed that [M(salpn)2] forms two different species in solution with and without an additional solvent molecule, where the relative distribution of the two species depends mainly on the ionic radius of the metal centre. Again, Ce(iv) behaves differently from the tetravalent actinides with a higher ratio of the solvent-molecule-coordinated species than the ratio expected from its ionic radius. Hence, this study is successful in observing subtle differences between 4f- (i.e. Ce) and 5f-elements (actinides; Th, U, Np, and Pu) both in the solid state and in solution on an analytically distinguishable level, and in relating the observed subtle differences to their electronic structure.

A systematic investigation is presented which examines the structural chemistry of anhydrous and hydrous ternary hexavalent uranium and neptunium dinitrato, trinitrato, and tetranitrato complexes. Using slow evaporation methods under acidic conditions the uranium and neptunium nitrate complexes γ-K[UO

Intrinsic properties of a compound (e.g., electronic structure, crystallographic structure, optical and magnetic properties) define notably its chemical and physical behavior. In the case of nanomaterials, these fundamental properties depend on the occurrence of quantum mechanical size effects and on the considerable increase of the surface to bulk ratio. Here, we explore the size dependence of both crystal and electronic properties of CeO

Copper(I)/(II) complexes and a zinc compound with polypyridylamine ligands (related to the tripodal ligand tris(2-pyridylmethyl)amine, tmpa) were synthesized. Crystallographic characterization was ...

A study of neptunium (Np) chemistry in the complex oxo-selenium system has been performed. Hereby, two sets of precipitation experiments were conducted, investigating the influence of the initial oxidation state of selenium using SeIVO2 and H2SeVIO4 with NpV in alkali nitrate solution, keeping the ratio of Np/Se constant. Surprising results were observed. Five novel neptunium and selenium bearing compounds have been obtained by slow evaporation from aqueous solution. The novel NpIV phase K4-x[Np(SeO3)4-x(HSeO3)x]·(H2O)1.5 (1) crystallizes in green-colored, plate-shaped crystals and was obtained by adding SeO2 and ANO3 to a NpV stock solution. Single-crystal X-ray diffraction reveals one-dimensional chain structures composed of square antiprismatic NpO8 polyhedra linked via four trigonal pyramidal SeO3 and HSeO3 units. Raman spectral analysis supports the presence of both selenite and hydroselenite due to the presence of corresponding modes within the spectra. The addition of selenic acid to a NpV stock so...

Production of actinide oxide powder via dry thermal decomposition of corresponding oxalates is currently carried out on the industrial scale at temperatures exceeding 500 °C. Although it is simple, this method presents some disadvantages such as high decomposition temperature with a direct effect on the surface area, pre-organised morphology of the nanoparticles affecting the sintering behaviour, etc. We have recently proposed the decomposition of AnIV-oxalates under hot compressed water conditions as a straightforward way to produce reactive actinide oxide nanocrystals. This method could be easily applied at low temperatures (95–250 °C) in order to generate highly crystalline nano-AnO2. We present here the formation conditions of AnO2 (An = Th, U, Np, and Pu) and some associated solid solutions, their stability, and grain growth during thermal treatment. The involvement of water molecules in the mechanism of the oxalate decomposition under the hot compressed water conditions has been demonstrated by an isotopic exchange reaction during the thermal treatment of the hydrated oxalate in H2[17O] through MAS-NMR and Raman techniques.

Two steps of a pyrochemical route for the recovery of actinides from spent metallic nuclear fuel are being investigated at JRC-Karlsruhe. The first step consists in electrorefining the fuel in molten salt medium implying aluminium cathodes. The second step is a chlorination process for the separation of actinides (An) from An-Al alloys formed on the cathodes. The chlorination process, in turn, consists of three steps; the distillation of adhered salt (1), the chlorination of An-Al by HCl/Cl2 under formation of AlCl3 and An chlorides (2), and the subsequent sublimation of AlCl3 (3). In the present work UAl2, UAl3, NpAl2, and PuAl2 were chlorinated with HCl(g) in a temperature range between 300 and 400 °C forming UCl4, NpCl4 or PuCl3 as the major An containing phases, respectively. Thermodynamic calculations were carried out to support the experimental work. The results showed a high chlorination efficiency for all used starting materials and indicated that the sublimation step may not be necessary when using HCl(g).

The organometallic tris‐cyclopentadienide actinide(III) (AnCp3) complexes were first reported about 50 years ago. However, up until now, only the NpCp3 solid state structure has been studied. Here we report on the solid state structures of UCp3 and PuCp3 which are isostructural to the Np analogue. The structural models are supported by theoretical calculations and compared to their lanthanide analogues. The observed trends in changes of bond lengths might be indicator for an increased covalency in the bonding in the tris‐cyclopentadienide actinide(III) complexes (AnCp3) compared to their lanthanide homologues.

Nickel(II) complexes of a series of tripodal ligands (and derivatives), e. g. [Ni(Me6tren)(DMF)](ClO4)2 (Me6tren = tris(2-dimethylaminoethyl)-amine) have been prepared and structurally characterized. The complexes were tested for their potential to be used as mediators for electroreductive coupling of butadiene and carbon dioxide. From the whole series the complex [Ni(Me5dien)(DMF)3](ClO4)2 (Me5dien = 1,1,4,7,7-pentamethyl-diethylenetriamine) proved to yield the highest amount of 3 hexene-1,6 diacid (HDS) and thus leading to the same result as the best nickel complex (with the ligand 2,4,4-trimethyl-1,5,9-triazacyclodecan, = N3) so far reported in the literature.

Introduction Nuwiq® (Human-cl rhFVIII) is a fourth generation recombinant FVIII, produced in a human cell line, without chemical modification or protein fusion. No inhibitors developed in studies with Nuwiq® in 201 previously treated patients with haemophilia A (HA). The immunogenicity, efficacy and safety of Nuwiq® in previously untreated patients (PUPs) with severe HA are being assessed in the ongoing NuProtect study. Methods The study, conducted across 38 centres worldwide, is evaluating 110 true PUPs of all ages and ethnicities enrolled for study up to 100 exposure days (EDs) or 5 years maximum. The primary objective is to assess the immunogenicity of Nuwiq® (inhibitor activity ≥0.6 BU) using the Nijmegen-modified Bethesda assay at a central laboratory. Results Data for 66 PUPs with ≥20 EDs from a preplanned interim analysis were analysed. High-titre (HT) inhibitors developed in 8 of 66 patients after a median of 11.5 EDs (range 6-24). Five patients developed low-titre inhibitors (4 transient). The cumulative incidence (95% confidence interval) was 12.8% (4.5%, 21.2%) for HT inhibitors and 20.8% (10.7%, 31.0%) for all inhibitors. During inhibitor-free periods, median annualized bleeding rates during prophylaxis were 0 for spontaneous bleeds and 2.40 for all bleeds. Efficacy was rated as “excellent” or “good” in treating 91.8% of bleeds. Efficacy of surgical prophylaxis was “excellent” or “good” for 8 (89%) procedures and “moderate” for 1 (11%). No tolerability concerns were evident. Conclusion These interim data show a cumulative incidence of 12.8% for HT inhibitors and convincing efficacy and tolerability in PUPs treated with Nuwiq®.

Introduction Nuwiq® (human-cl rhFVIII) is a 4th generation recombinant human FVIII, without chemical modification or protein fusion, produced in a human cell-line. Aims/Methods This study (NuPreviq) was a prospective, open-label, multicentre, phase IIIb study of the efficacy and safety of personalized prophylaxis with Nuwiq® in 66 previously treated adults with severe haemophilia A. NuPreviq had three phases: (i) a 72-h pharmacokinetic (PK) phase; (ii) a 1–3 month standard prophylaxis phase; and (iii) a 6-month personalized prophylaxis phase. The personalized prophylaxis regimen was based on individual PK modelling for each patient according to whether their PK profile most closely fitted a two- or one-compartment model (NuPreviq approach). In cases of uncertainty, a noncompartment model was applied. Results The median dosing interval during personalized prophylaxis was 3.5 days, with 57% of patients on ≤2 weekly dosing. Mean annualized bleeding rates during personalized prophylaxis were 1.45 (median [interquartile range, IQR]: 0 [0, 1.9]) for all bleeds, 0.79 (median [IQR]: 0 [0, 0]) for spontaneous bleeds, and 0.91 (median [IQR]: 0 [0, 0]) for joint bleeds. During personalized prophylaxis, 83.1% of patients were spontaneous bleed-free. Compared with standard prophylaxis, median weekly prophylaxis dose was reduced by 7.2% from 100.0 to 92.8 IU kg−1 during the last 2 months of personalized prophylaxis. There were no FVIII inhibitors or treatment-related serious or severe adverse events. Conclusion PK-guided personalized prophylaxis with Nuwiq® provided bleeding protection and enabled the dosing interval to be extended to twice weekly or less in many patients and an overall dose reduction.

BACKGROUND Accurate determination of coagulation factor VIII activity (FVIII:C) is essential for effective and safe FVIII replacement therapy. FVIII C can be measured by one-stage and chromogenic substrate assays (OSAs and CSAs, respectively); however, there is significant interlaboratory and interassay variability. AIMS This international comparative field study characterized the behaviour of OSAs and CSAs used in routine laboratory practice to measure the activity of Nuwiq® (human-cl rhFVIII, simoctocog alfa), a fourth-generation recombinant human FVIII produced in a human cell line. METHODS FVIII-deficient plasma was spiked with Nuwiq® or Advate® at 1, 5, 30 and 100 international units (IU)/dL. Participating laboratories analysed the samples using their routine procedures and equipment. Accuracy, inter- and intralaboratory variation, CSA:OSA ratio and the impact of different OSA and CSA reagents were assessed. RESULTS Forty-nine laboratories from 9 countries provided results. Mean absolute FVIII:C was comparable for both products at all concentrations with both OSA and CSA, with interproduct ratios (Nuwiq® :Advate® ) of 1.02-1.13. Mean recoveries ranged from 97% to 191% for Nuwiq® , and from 93% to 172% for Advate® , with higher recoveries at lower concentrations. Subgroup analyses by OSA and CSA reagents showed minor variations depending on reagents, but no marked differences between the two products. CSA:OSA ratios based on overall means ranged from 0.99 to 1.17 for Nuwiq® and from 1.01 to 1.17 for Advate® . CONCLUSIONS Both OSAs and CSAs are suitable for the measurement of FVIII:C of Nuwiq® in routine laboratory practice, without the need for a product-specific reference standard.