Reductive hydrothermal conversion of uranyl oxalates into UO monitored by XANES analyses.

Hydrothermal conversion of actinide oxalates has recently gained attention as an innovative fabrication route for nuclear fuels but has remained mainly limited to tetra- or tri-valent cations. We report herein the reductive conversion of mixtures of uranyl and oxalate ions into UO oxides under mild hydrothermal conditions ( = 250 °C). A multi-parametric study first led to specifying the optimal conditions in terms of pH, oxalate/U ratio and duration to provide a quantitative precipitation of uranium in the hyper-stoichiometric dioxide form with pH = 0.

Novel high-pressure/high-temperature reactor cell for in situ and operando x-ray absorption spectroscopy studies of heterogeneous catalysts at synchrotron facilities.

This paper presents the development of a novel high-pressure/high-temperature reactor cell dedicated to the characterization of catalysts using synchrotron x-ray absorption spectroscopy under operando conditions. The design of the vitreous carbon reactor allows its use as a plug-flow reactor, monitoring catalyst samples in a powder form with a continuous gas flow at high-temperature (up to 1000 °C) and under high pressure (up to 1000 bar) conditions, depending on the gas environment. The high-pressure/high-temperature reactor cell incorporates an automated gas distribution system and offers the capability to operate in both transmission and fluorescence detection modes.

Yttrium speciation variability in bauxite residues of various origins, ages and storage conditions.

Bauxite residues (BRs) are highly alkaline wastes generated during alumina production from bauxite ore. Billions of tons have been accumulating worldwide for more than 100 years, they are stored in various forms, and pose environmental and societal issues. At the same time, BRs are promising secondary sources for the production of critical metals including rare earth elements (REEs).

Efficacy and Safety of Eculizumab in Pediatric Patients Affected by Shiga Toxin-Related Hemolytic and Uremic Syndrome: A Randomized, Placebo-Controlled Trial.

Significance Statement: Shiga toxin-related hemolytic uremic syndrome (STEC-HUS) is a serious condition, characterized by multiorgan thrombotic microangiopathy, mainly affecting children. Renal involvement is severe, with approximately half of patients requiring dialysis. So far, no specific treatment has been proven efficient in STEC-HUS.

Molecular and clinicopathologic characterization of pediatric histiocytoses.

The spectrum of somatic mutations in pediatric histiocytoses and their clinical implications are not fully characterized, especially for non-Langerhans cell histiocytosis (-LCH) subtypes. A cohort of 415 children with histiocytosis from the French histiocytosis registry was reviewed and analyzed for BRAF . Most BRAF samples were analyzed by next-generation sequencing (NGS) with a custom panel of genes for histiocytosis and myeloid neoplasia.

Bacterial Metabolites and Particle Size Determine Cerium Oxide Nanomaterial Biotransformation.

Soil is a major receptor of manufactured nanomaterials (NMs) following unintentional releases or intentional uses. Ceria NMs have been shown to undergo biotransformation in plant and soil organisms with a partial Ce(IV) reduction into Ce(III), but the influence of environmentally widespread soil bacteria is poorly understood. We used high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS) with an unprecedented detection limit to assess Ce speciation in a model soil bacterium () exposed to CeO NMs of different sizes and shapes.

Following a Silent Metal Ion: A Combined X-ray Absorption and Nuclear Magnetic Resonance Spectroscopic Study of the Zn Cation Dissipative Translocation between Two Different Ligands.

The dissipative translocation of the Zn ion between two prototypical coordination complexes has been investigated by combining X-ray absorption and H NMR spectroscopy. An integrated experimental and theoretical approach, based on state-of-the-art Multivariate Curve Resolution and DFT based theoretical analyses, is presented as a means to understand the concentration time evolution of all relevant Zn and organic species in the investigated processes, and accurately characterize the solution structures of the key metal coordination complexes. Specifically, we investigate the dissipative translocation of the Zn cation from hexaaza-18-crown-6 to two terpyridine moieties and back again to hexaaza-18-crown-6 using 2-cyano-2-phenylpropanoic acid and its -chloro derivative as fuels.

Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium : Evidences From HERFD-XANES and Nano-XRF.

Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.

Non-linear release dynamics for a CeO nanomaterial embedded in a protective wood stain, due to matrix photo-degradation.

The release of CeO-bearing residues during the weathering of an acrylic stain enriched with CeO nanomaterial designed for wood protection (Nanobyk brand additive) was studied under two different scenarios: (i) a standard 12-weeks weathering protocol in climate chamber, that combined condensation, water spraying and UV-visible irradiation and (ii) an alternative accelerated 2-weeks leaching batch assay relying on the same weathering factors (water and UV), but with a higher intensity of radiation and immersion phases. Similar Ce released amounts were evidenced for both scenarios following two phases: one related to the removal of loosely bound material with a relatively limited release, and the other resulting from the degradation of the stain, where major release occurred. A non-linear evolution of the release with the UV dose was evidenced for the second phase.

A new high temperature reactor for operando XAS: Application for the dry reforming of methane over Ni/ZrO catalyst.

The construction of a high-temperature reaction cell for operando X-ray absorption spectroscopy characterization is reported. A dedicated cell was designed to operate as a plug-flow reactor using powder samples requiring gas flow and thermal treatment at high temperatures. The cell was successfully used in the reaction of dry reforming of methane (DRM).

Multi-scale X-ray computed tomography to detect and localize metal-based nanomaterials in lung tissues of in vivo exposed mice.

In this methodological study, we demonstrated the relevance of 3D imaging performed at various scales for the ex vivo detection and location of cerium oxide nanomaterials (CeO-NMs) in mouse lung. X-ray micro-computed tomography (micro-CT) with a voxel size from 14 µm to 1 µm (micro-CT) was combined with X-ray nano-computed tomography with a voxel size of 63 nm (nano-CT). An optimized protocol was proposed to facilitate the sample preparation, to minimize the experimental artifacts and to optimize the contrast of soft tissues exposed to metal-based nanomaterials (NMs).

High-Energy Resolution Fluorescence Detected X-Ray Absorption Spectroscopy: A Powerful New Structural Tool in Environmental Biogeochemistry Sciences.

The study of the speciation of highly diluted elements by X-ray absorption spectroscopy (XAS) is extremely challenging, especially in environmental biogeochemistry sciences. Here we present an innovative synchrotron spectroscopy technique: high-energy resolution fluorescence detected XAS (HERFD-XAS). With this approach, measurement of the XAS signal in fluorescence mode using a crystal analyzer spectrometer with a ∼1-eV energy resolution helps to overcome restrictions on sample concentrations that can be typically measured with a solid-state detector.

Identification of key structural features of the elusive Cu-Aβ complex that generates ROS in Alzheimer's disease.

Oxidative stress is linked to the etiology of Alzheimer's disease (AD), the most common cause of dementia in the elderly. Redox active metal ions such as copper catalyze the production of Reactive Oxygen Species (ROS) when bound to the amyloid-β (Aβ) peptide encountered in AD. We propose that this reaction proceeds through a low-populated Cu-Aβ state, denoted the "catalytic in-between state" (CIBS), which is in equilibrium with the resting state (RS) of both Cu(i)-Aβ and Cu(ii)-Aβ.

A Trishistidine Pseudopeptide with Ability to Remove Both Cu and Cu from the Amyloid-β Peptide and to Stop the Associated ROS Formation.

The pseudopeptide L, derived from a nitrilotriacetic acid scaffold and functionalized with three histidine moieties, is reminiscent of the amino acid side chains encountered in the Alzheimer's peptide (Aβ). Its synthesis and coordination properties for Cu and Cu are described. L efficiently complex Cu in a square-planar geometry involving three imidazole nitrogen atoms and an amidate-Cu bond.

Evidence that Soil Properties and Organic Coating Drive the Phytoavailability of Cerium Oxide Nanoparticles.

The ISO-standardized RHIZOtest is used here for the first time to decipher how plant species, soil properties, and physical-chemical properties of the nanoparticles and their transformation regulate the phytoavailability of nanoparticles. Two plants, tomato and fescue, were exposed to two soils with contrasted properties: a sandy soil poor in organic matter and a clay soil rich in organic matter, both contaminated with 1, 15, and 50 mg·kg of dissolved Ce(SO), bare and citrate-coated CeO nanoparticles. All the results demonstrate that two antagonistic soil properties controlled Ce uptake.

Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese-Radical Coordination Framework.

The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn(NITIm)]ClO} (1) (NITImH = 2-(2-imidazolyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm) are reduced to their diamagnetic aminoxyl form (denoted NIT). Upon cooling, the high-temperature species {[Mn(NITIm)]ClO} (1) turns into the low-temperature species {[Mn(NIT)(NITIm)]ClO} (1) around 274 K, while on heating the process is reversed at about 287 K. This valence tautomeric phenomenon is supported by temperature-dependent magnetic susceptibility measurements, differential scanning calorimetry (DSC), crystal structure determination, UV-vis absorption, X-ray absorption (XAS), and emission (XES) and electron paramagnetic resonance (EPR) spectroscopies in the solid state.

Determination of the local structure of CsBiPbTe (x = 0, 0.5) by X-ray absorption spectroscopy.

We have studied the local structure and valence electronic unoccupied states of thermoelectric CsBiTe and superconducting CsBiPbTe (T ∼ 3 K) by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) measurements. The Bi-L edge EXAFS reveals wide Bi-Te distance distribution for both compounds indicating complex atomic arrangements in the studied system. The mean square relative displacements (MSRDs) of the Bi-Te bond distances appear largely increased in Pb substituted system due to larger overall local disorder, however, one of the Bi-Te bonds shows a reduced disorder.

Zinc(II) Binding Site to the Amyloid-β Peptide: Insights from Spectroscopic Studies with a Wide Series of Modified Peptides.

The Zn(II) ion has been linked to Alzheimer's disease (AD) due to its ability to modulate the aggregating properties of the amyloid-β (Aβ) peptide, where Aβ aggregation is a central event in the etiology of the disease. Delineating Zn(II) binding properties to Aβ is thus a prerequisite to better grasp its potential role in AD. Because of (i) the flexibility of the Aβ peptide, (ii) the multiplicity of anchoring sites, and (iii) the silent nature of the Zn(II) ion in most classical spectroscopies, this is a difficult task.

High unacylated ghrelin levels support the concept of anorexia in infants with prader-willi syndrome.

Background: Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder with different nutritional phases from suckling deficit with failure to thrive to early onset of obesity. Hyperghrelinemia has been described in PWS long before the development of obesity. Ghrelin is found in both acylated (AG) and unacylated (UAG) forms in the circulation.

XAS Investigation of Silver(I) Coordination in Copper(I) Biological Binding Sites.

Silver(I) is an unphysiological ion that, as the physiological copper(I) ion, shows high binding affinity for thiolate ligands; its toxicity has been proposed to be due to its capability to replace Cu(I) in the thiolate binding sites of proteins involved in copper homeostasis. Nevertheless, the nature of the Ag(I)-thiolate complexes formed within cells is poorly understood, and the details of Ag(I) coordination in such complexes in physiologically relevant conditions are mostly unknown. By making use of X-ray absorption spectroscopy (XAS), we characterized the Ag(I) binding sites in proteins related to copper homeostasis, such as the chaperone Atox1 and metallothioneins (MTs), as well as in bioinspired thiolate Cu(I) chelators mimicking these proteins, in solution and at physiological pH.

Reactivity of Cys4 zinc finger domains with gold(III) complexes: insights into the formation of "gold fingers".

Gold(I) complexes such as auranofin or aurothiomalate have been used as therapeutic agents for the treatment of rheumatoid arthritis for several decades. Several gold(I) and gold(III) complexes have also shown in vitro anticancer properties against human cancer cell lines, including cell lines resistant to cisplatin. Because of the thiophilicity of gold, cysteine-containing proteins appear as likely targets for gold complexes.

Haploinsufficiency of the miR-873/miR-876 microRNA cluster is associated with craniofacial abnormalities.

MicroRNA haploinsufficiency has been associated with developmental defects in only a limited number of cases. Here we report a de novo genomic microdeletion that includes the LINGO2 gene as well as two microRNA genes, MIR873 and MIR876, in a patient with craniofacial abnormalities - in particular macrocephaly and hypertelorism - and learning difficulties. Subsequent analysis revealed that the microRNAs affected by this de novo microdeletion form a mammalian-lineage, neuronal tissue-enriched cluster.

Zinc speciation in the suspended particulate matter of an urban river (Orge, France): influence of seasonality and urbanization gradient.

Among trace metal pollutants, zinc is the major one in the rivers from the Paris urban area, such as the Orge River, where Zn concentration in the suspended particulate matter (SPM) can reach 2000 mg/kg in the most urbanized areas. In order to better understand Zn cycling in such urban rivers, we have determined Zn speciation in SPM as a function of both the seasonal water flow variations and the urbanization gradient along the Orge River. Using TEM/SEM-EDX and linear combination fitting (LCF) of EXAFS data at the Zn K-edge, we show that Zn mainly occurs as tetrahedrally coordinated Zn(2+) sorbed to ferrihydrite (37-46%), calcite (0-37%), amorphous SiO2 (0-21%), and organic-P (0-30%) and as octahedrally coordinated Zn(2+) in the octahedral layer of phyllosilicates (18-25%).

Transfer, transformation, and impacts of ceria nanomaterials in aquatic mesocosms simulating a pond ecosystem.

Mesocosms are an invaluable tool for addressing the complex issue of exposure during nanoecotoxicological testing. This experimental strategy was used to take into account parameters as the interactions between the NPs and naturally occurring (in)organic colloids (heteroaggregation), or the flux between compartments of the ecosystems (aqueous phase, sediments, biota) when assessing the impacts of CeO2 NPs in aquatic ecosystems. In this study, we determine the transfer, redox transformation, and impacts of 1 mg L(-1) of bare and citrate coated CeO2-NPs toward an ecologically relevant organism (snail, Planorbarius corneus) exposed 4 weeks in a complex experimental system mimicking a pond ecosystem.