scholarly journals Alkali Uranyl Borates: Bond Length, Equatorial Coordination and 5f States

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 56
Author(s):  
Myrtille O.J.Y. Hunault ◽  
Denis Menut ◽  
Olivier Tougait
Keyword(s):  
Solid State ◽  
Bond Length ◽  
Absorption Spectroscopy ◽  
High Energy ◽  
Crystallographic Structure ◽  
X Ray ◽  
Coordination Change ◽  
X Ray Absorption ◽  
Bond Covalency

Three uranyl borates, UO2B2O4, LiUO2BO3 and NaUO2BO3, have been prepared by solid state syntheses. The influence of the crystallographic structure on the splitting of the empty 5f and 6d states have been probed using High Energy Resolved Fluorescence Detected X-ray Absorption Spectroscopy (HERFD-XAS) at the uranium M4-edge and L3-edge respectively. We demonstrate that the 5f splitting is increased by the decrease of the uranyl U-Oax distance, which in turn correlates with an increased bond covalency. This is correlated to the equatorial coordination change of the uranium. The role of the alkalis as charge compensating the axial oxygen of the uranyl is discussed.

Revealing the charge/discharge mechanism of Na–O2 cells by in situ soft X-ray absorption spectroscopy

2018 ◽  
Vol 11 (8) ◽  
pp. 2073-2077 ◽  
Author(s):  
Mohammad N. Banis ◽  
Hossein Yadegari ◽  
Qian Sun ◽  
Tom Regier ◽  
Teak Boyko ◽  
...  
Keyword(s):  
Energy Density ◽  
Absorption Spectroscopy ◽  
High Energy ◽  
High Energy Density ◽  
X Ray ◽  
Discharge Mechanism ◽  
X Ray Absorption ◽  
Charge Discharge

Developing high energy density batteries, such as metal–air systems, requires a good understanding of their underlying electrochemical principles.

scholarly journals Iron Speciation in Different Saharan Dust Advections and Effect of the Procedural Blank on the Results From X-ray Absorption Spectroscopy and Selective Leaching Experiments

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 735
Author(s):  
Chiara Petroselli ◽  
Beatrice Moroni ◽  
Stefano Crocchianti ◽  
Roberta Selvaggi ◽  
Francesco Soggia ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Saharan Dust ◽  
Residual Fraction ◽  
Selective Leaching ◽  
Iron Speciation ◽  
X Ray ◽  
Fe Speciation ◽  
Leaching Experiments ◽  
X Ray Absorption

In this work, we applied X-ray Absorption Spectroscopy (XAS) and selective leaching experiments for investigating iron speciation in different dust advections collected on different unwashed quartz fiber filters. XAS analysis evidenced a predominance of Fe(III) in 6-fold coordination for Saharan dust and a trend towards Fe(II) and 4-fold coordination in the order: Saharan dust, mixed Saharan, and non-Saharan aerosol samples. The role of the sampling substrate was evaluated explicitly, including in the analysis a set of blank filters. We were able to pinpoint the possible contribution to the overall XAS spectrum of the residual Fe on quartz as the concentration decrease towards the blank value. In particular, the filter substrate showed a negligible effect on the structural trend mentioned above. Furthermore, selective leaching experiments evidenced a predominance of the residual fraction on Fe speciation and indicated the lowest Fe concentrations for which the blank contribution is <20% are 1 μ g for the first three steps of the procedure (releasing the acid-labile, reducible and oxidizable phases, respectively) and 10 μ g for the last step (dissolving the insoluble residuals).

scholarly journals X-Ray Absorption Spectroscopy Measurements of Cu-ProIAPP Complexes at Physiological Concentrations

2019 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Emiliano De Santis ◽  
Emma Shardlow ◽  
Francesco Stellato ◽  
Olivier Proux ◽  
Giancarlo Rossi ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Absorption Spectroscopy ◽  
Amyloid Fibrils ◽  
High Energy ◽  
Islet Amyloid ◽  
X Ray ◽  
X Ray Absorption

The amyloidogenic islet amyloid polypeptide (IAPP) and the associated pro-peptide ProIAPP1–48 are involved in cell death in type 2 diabetes mellitus. It has been observed that interactions of this peptide with metal ions have an impact on the cytotoxicity of the peptides as well as on their deposition in the form of amyloid fibrils. In particular, Cu(II) seems to inhibit amyloid fibril formation, thus suggesting that Cu homeostasis imbalance may be involved in the pathogenesis of type 2 diabetes mellitus. We performed X-ray Absorption Spectroscopy (XAS) measurements of Cu(II)-ProIAPP complexes under near-physiological (10 μM), equimolar concentrations of Cu(II) and peptide. Such low concentrations were made accessible to XAS measurements owing to the use of the High Energy Resolved Fluorescence Detection XAS facility recently installed at the ESRF beamline BM16 (FAME-UHD). Our preliminary data show that XAS measurements at micromolar concentrations are feasible and confirm that ProIAPP1–48-Cu(II) binding at near-physiological conditions can be detected.

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