Oxygen vacancy clusters in bulk cerium oxide and the impact of gold atoms

Ceria is important for catalysis due to its ability to form and utilize oxygen vacancies during redox reactions. Understanding the dynamic formation of the oxygen vacancies has contributed to the development of efficient catalytic processes. Here, we demonstrate the presence of oxygen vacancy clusters in the bulk of ceria and gold/ceria catalysts upon anaerobic carbon monoxide oxidation and describe their interplay with the orbital hybridization of Ce3+ 4f and 5d states. Observations are made using in situ X-ray Raman scattering spectroscopy at O K-and Ce N4,5-edges and in situ X-ray diffraction. These, combined with multiplet calculations, allow detection of the formation of Ce3+ in gold/ceria upon low temperature carbon monoxide oxidation. The modifications observed at the O K-edge reflect the rearrangement of the bulk oxygen sublattice. Density-functional theory calculations show vacancy ordering in the bulk, and explain modifications at the O K-edge, involving the hybridization of the Ce 4f and 5d and O 2p orbitals

Quantification of non-bridging oxygens in silicates using X-ray Raman scattering

International audienceDetecting and quantifying non-bridging oxygen (NBO) atoms is of particular interest for understanding the physical properties of melts or compressed materials, and requires an unequivocal spectral signature usable during in-situ measurements. In this paper, we evidence a low-energy feature of NBO in lithium silicate crystals using X-ray Raman scattering (XRS) spectroscopy around the energy losses of the oxygen K edge. A specific peak at 534-535 eV in the edge onset is unequivocally attributed to the presence of NBO. Its intensity is used to quantify NBO in lithium silicate glasses. A similar feature at low energy has also been evidenced in Na 2 SiO 3 and MgSiO 3 , generalizing the method to other alkali and alkali-earth silicates. This non-destructive method of NBO quantification, which is based on an X-ray inelastic scattering technique, can be extended to other spectroscopies such as electron-energy loss spectroscopy, soft x-ray absorption spectroscopy at the oxygen K edge

First-principles modeling of x-ray Raman scattering spectra

International audienceAn efficient technique for calculating x-ray Raman scattering spectra at the K edge in the framework of a single-particle theory is presented. It is based on a recursive method to compute the dynamic structure factor as a continued fraction without requiring the explicit calculation of high-lying unoccupied electronic states. Multipole transitions are calculated to provide a full account of the q-dependence of K edges recorded in a series of lithium-bearing reference compounds, namely LiBO2 , Li2CO3 , Li2O, and LiF. The good agreement obtained between experimental and theoretical spectra validates our approach and provides a solid foundation for analyzing K edges beyond the dipole approximation

Theranostics of Primary Prostate Cancer: Beyond PSMA and GRP-R

The imaging of Prostate-Specific Membrane Antigen (PSMA) is now widely used at the initial staging of prostate cancers in patients with a high metastatic risk. However, its ability to detect low-grade tumor lesions is not optimal. Methods: First, we prospectively performed neurotensin receptor-1 (NTS1) IHC in a series of patients receiving both [68Ga]Ga-PSMA-617 and [68Ga]Ga-RM2 before prostatectomy. In this series, PSMA and GRP-R IHC were also available (n = 16). Next, we aimed at confirming the PSMA/GRP-R/NTS1 expression profile by retrospective autoradiography (n = 46) using a specific radiopharmaceuticals study and also aimed to decipher the expression of less-investigated targets such as NTS2, SST2 and CXCR4. Results: In the IHC study, all samples with negative PSMA staining (two patients with ISUP 2 and one with ISUP 3) were strongly positive for NTS1 staining. No samples were negative for all three stains—for PSMA, GRP-R or NTS1. In the autoradiography study, binding of [111In]In-PSMA-617 was high in all ISUP groups. However, some samples did not bind or bound weakly to [111In]In-PSMA-617 (9%). In these cases, binding of [111n]In-JMV 6659 and [111In]In-JMV 7488 towards NTS1 and NTS2 was high. Conclusions: Targeting PSMA and NTS1/NTS2 could allow for the detection of all intraprostatic lesions

Joint Bone Spine

PURPOSE: Post-operative instrumented spine infection (PISI) is an infrequent complication. Diagnosis of spinal implant infection can be difficult, especially in case of chronic infection. METHODS: This retrospective study attempts to evaluate the diagnostic performance of [18F]fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in PISI. Imagings were performed between April 2010 and June 2018 among patients referred for suspected chronic spinal implant infection. PET/CT were performed more than 12 weeks after surgery. PET/CT images were re-interpreted independently by two nuclear medicine physicians without knowledge of the patient's conditions. PET/CT data were analyzed both visually and semi-quantitatively (SUVmax). MRI results were collected from medical records. The final diagnosis of infection was based on bacteriological cultures or a twelve-month follow-up. RESULTS: Forty-nine PET/CT were performed in 44 patients (22 women, median age 65.0 years). Twenty-two patients had a diagnosis of infection during follow-up. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for PET/CT were 86.4%, 81.5%, 79.2%, and 88.0%. Sensitivity, specificity, PPV and NPV were 66.7%, 75.0%, 66.0%, 75.0% respectively for MRI and 50.0%, 92.6%, 84.6% and 69.4% for serum C-reactive protein (CRP). Although these values were higher for PET/CT than for MRI or CRP, the differences were not statistically significant. In this setting, false positives with PET/CT can be observed in case of previous spine infection or adjacent segments disc disease. False negatives can result of extensive instrumented arthrodesis or infection with low virulence bacteria. CONCLUSION: PET/CT is useful for the diagnosis of PISI. These results should be evaluated in further prospective study