University of Lorraine

About: University of Lorraine is a education organization based out in Nancy, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 11942 authors who have published 25010 publications receiving 425227 citations. The organization is also known as: Lorraine University.

From hydrated Ni3(OH)2(C8H4O4)2(H2O)4 to anhydrous Ni2(OH)2(C8H4O4): impact of structural transformations on magnetic properties.

Abstract: Dehydration of the hybrid compound [Ni3(OH)2(tp)2(H2O)4] (1) upon heating led to the sequential removal of coordinated water molecules to give [Ni3(OH)2(tp)2(H2O)2] (2) at T1 = 433 K and thereafter anhydrous [Ni2(OH)2(tp)] (3) at T2 = 483 K. These two successive structural transformations were thoroughly characterized by powder X-ray diffraction assisted by density functional theory calculations. The crystal structures of the two new compounds 2 and 3 were determined. It was shown that at T1 (433 K) the infinite nickel oxide chains built of the repeating structural unit [Ni3(μ3-OH)2](4+) in 1 collapse and lead to infinite porous layers, forming compound 2. The second transformation at T2 (483 K) gave the expected anhydrous compound 3, which is isostructural with Co2(OH)2(tp). These irreversible transitions directly affect the magnetic behavior of each phase. Hence, 1 was found to be antiferromagnetic at TN = 4.11 K, with metamagnetic behavior with a threshold field Hc of ca. 0.6 T. Compound 2 exhibits canted antiferromagnetism below TN = 3.19 K, and 3 is ferromagnetic below TC = 4.5 K.

The use of theranostic gadolinium-based nanoprobes to improve radiotherapy efficacy

Abstract: A new efficient type of gadolinium-based theranostic agent (AGuIX) has recently been developed for magnetic resonance imaging (MRI)-guided radiotherapy. These new particles consist of a polysiloxane network surrounded by a number of gadolinium chelates, usually 10. Due to their small size (<5 nm), AGuIX typically exhibit biodistributions that are almost ideal for diagnostic and therapeutic purposes. For example, while a significant proportion of these particles accumulate in tumours, the remainder is rapidly eliminated by the renal route. In addition, these particles present no evidence of toxicity, in the absence of irradiation with up to 10 times the planned dose for clinical trials. AGuIX particles have been proven to act as efficient radiosensitizers in a large variety of experimental in vitro scenarios, including different radioresistant cell lines, irradiation energies, and radiation sources (sensitizing enhancement ratio ranging from 1.1 to 2.5). Preclinical studies have also demonstrated the impact of these particles on different heterotopic and orthotopic tumours, with both intra-tumoural or intravenous injection routes. A significant therapeutical effect has been observed in all contexts. Furthermore, MRI monitoring was proven to efficiently aid in determining a radiotherapy protocol and assessing tumour evolution following treatment. The usual theoretical models, based on energy attenuation and macroscopic dose enhancement, cannot account for all the results that have been obtained. Only theoretical models, which take into account the Auger electron cascades that occur between the different atoms constituting the particle and the related high radical concentrations in the vicinity of the particle, provide an explanation for the complex cell damage and death observed.

New tools for the analysis and validation of Cryo-EM maps and atomic models

Abstract: Recent advances in the field of electron cryo-microscopy (cryo-EM) have resulted in a rapidly increasing number of atomic models of bio-macromolecules solved using this technique and deposited in the Protein Data Bank and the Electron Microscopy Data Bank. Similar to macromolecular crystallography, validation tools for these models and maps are required. While some of these validation tools may be borrowed from crystallography, new methods specifically for cryo-EM validation are required. We discuss new computational methods and tools implemented in Phenix, including d99 to estimate resolution, phenix.auto_sharpen to improve maps, and phenix.mtriage to analyze cryo-EM maps. We suggest that cryo-EM half-maps and masks are deposited to facilitate evaluation and validation of cryo-EM derived atomic models and maps. We also present the application of these tools to deposited cryo-EM atomic models and maps.