The present study focuses on the development of a novel Zr-12Nb-3Sn alloy displaying a body-centered tetragonal (BCT) / beta dual-phase microstructure and engineered to achieve a superior combination of high strength and low elastic modulus. The BCT phase is shown to play a critical role in enhancing strength without increasing elastic modulus. Comprehensive analyses using in situ straining electron backscatter diffraction (EBSD) experiment and transmission electron microscopy (TEM) were conducted to characterize the microstructure of the BCT phase and the associated deformation mechanisms, including dislocation slip, stress-induced reversion from BCT to beta transformation, and mechanical twinning. The present findings reveal that the BCT phase and mechanical twinning both contribute to material strengthening, whereas the stress-induced reversion of the BCT phase to beta acts as a mechanism for stress relaxation. As a result, the alloy demonstrates exceptional mechanical performance, achieving a yield strength exceeding 1200 MPa, an elastic modulus of approximately 70 GPa, and an elongation of similar to 13%.
We report the archetypal representatives of single-molecule magnets (SMMs) based on the “most prolate” lanthanide ion: Yb(BHT)3 (1) and Yb(DBP)3 (2) (BHT = 2,6-di-tert-butyl-4-methylphenolate, DBP = 2,6-di-tert-butylphenolate). The coordination sphere of the metal center was designed to accommodate only three aryloxide ligands yielding highly symmetric nearly trigonal planar geometry which maximizes the magnetic anisotropy associated with the prolate character of the mJ = |7/2| of YbIII. Detailed magnetic and optical studies combined with cantilever torque magnetometry measurements and ab initio calculations, unambiguously unravel the giant magnetic easy axis anisotropy, with the easy magnetization axis perpendicular to the trigonal coordination plane. Our results highlight an exceptional magnetic splitting of the 2F7/2 state (> 1500 cm-1), close to the maximum theoretical value, as well as extremely pure composition of the wavefunction describing each Kramers doublets (KD). This best possible electrostatic environment for the stabilization of the prolate f-electron density does not favour Orbach relaxation, but rather a Raman relaxation process. Nevertheless, the low temperature emission spectra demonstrate that the very strong YbIII anisotropy indeed induces an extremely rare and strong splitting of the 2F7/2 KD in both compounds, as the near infra-red (IR) emissions arising from radiative deexcitation toward the 2F7/2 ground state span over 1695 (1) and 1573 cm−1 (2) at 4 K. Based on this observation, a direct link between the YbIII position with respect to the trigonal coordination environment created by the oxygen atoms and the IR emission can be drawn in solid-state, but also in solution. This allows for going well beyond the crystal structure determination and provides hints about the geometry of such systems in solution.
Background Echinococcosis is a zoonotic disease caused by cestodes of the genus Echinococcus. Alveolar echinococcosis (AE), caused by E. multilocularis, primarily affects the liver and shows infiltrative, tumor-like growth of the metacestode stage. If untreated, AE is lethal. AE remains a neglected disease with current treatments based on albendazole or mebendazole that are parasitostatic, and not curative, underscoring the need for more effective therapies. Niclosamide is a chlorinated salicylanilide derivative with proven activities against intestinal helminths but is inactive against tissue-dwelling helminths due to poor absorption and limited bioavailability. In this study, we repurposed niclosamide ethanolamine (NEN), a formulation with improved systemic exposure, for the treatment of E. multilocularis infection in vitro and in vivo. Methodology/Principal Findings We assessed the in vitro efficacy of niclosamide and NEN against E. multilocularis metacestode vesicles (IC50<0.2 µM) and primary parasite cells (IC50<0.3 µM), with active concentrations largely corresponding to NEN levels reachable in the liver. Metabolic analysis suggested that NEN acts as a mitochondrial uncoupler. Electron microscopy showed that NEN-treatments induced profound structural damage in the metacestode vesicle tissue, but mitochondrial ultrastructure was not notably affected. In mice intraperitoneally infected with E. multilocularis, NEN was orally administered during 9 weeks either alone, or in combination with albendazole. Pharmacokinetic analyses showed that NEN reached blood level concentrations above 1 µM. However, the parasite burden in NEN-treated mice was not significantly reduced. Conclusions/Significance Although niclosamide and NEN demonstrated potent activity against E. multilocularis in vitro, this efficacy did not translate in the mouse model. The lack of in vivo activity could be attributed to several factors such as infection model, limited drug uptake by the parasite in the animal, or the rapid metabolization of the compound. Future studies should explore novel niclosamide derivatives and formulations to enhance efficacy against AE in vivo. ### Competing Interest Statement The authors have declared no competing interest.
Using light as an external stimulus, photoswitchable catalysis offers attractive opportunities to modulate the activity and selectivity of catalytic systems on demand and remotely, with high spatial and temporal precision. Consequently, the development of photoswitchable catalysts has attracted considerable attention from the chemist community in recent decades, leading to various photoresponsive species with diverse properties. Among these, only a few examples incorporate N -heterocyclic carbenes (NHCs), despite their unique electronic and steric properties and their ubiquity in organic and organometallic catalysis. This review highlights recent advances in this emerging research area from the first reported species in 2009 to the present day, with particular emphasis on the synthesis of photoswitchable NHCs and their corresponding transition metal complexes for application in catalysis. Future perspectives in the field are also discussed.
