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Solvent-dependent electronic dichotomy in zinc complexes with non-innocent ligands: divalent Zn (+II) vs. monovalent Zn (+I) forms
No full textInternational audienceThe relative stabilities and the electronic structures of zinc complexes bearing non-innocent ligands, associated with various oxidation states, are examined in this computational study, with a particular attention on the influence of solvent polarity, modeled by explicit, implicit, and hybrid solvation approaches. Notably, we show that the stabilities and the electronic configuration of both the divalent species, described as a Zn(II) center coordinated to a fully reduced ligand (dianion), and the monovalent Zn(+I) species, described as a Zn(I) center bound to a one-electron reduced ligand (radical anion), as a biradical, are highly sensitive to the polarity of the solvent. This study underscores the importance of performing geometry optimizations within the solvation model and highlights the use of structural features and bonding analysis tools in elucidating electronic structures
Interfacial reactions between atomic layer deposited NiO x hole transport layers and metal halide perovskites in n-i-p perovskite solar cells
No full textInternational audienceWe observe defect formation at the metal halide perovskite (MHP)/ALD-NiO x interface, as revealed by HAXPES. Introduction of an organic buffer layer minimizes these defects, leading to improved device performance
Learn2Reg 2024: New Benchmark Datasets Driving Progress on New Challenges
No full textInternational audienceMedical image registration is critical for clinical applications, and fair benchmarking of different methods is essential for monitoring ongoing progress in the field. To date, the Learn2Reg 2020-2023 challenges have released several complementary datasets and established metrics for evaluations. Building on this foundation, the 2024 edition expands the challenge’s scope to cover a wider range of registration scenarios, particularly in terms of modality diversity and task complexity, by introducing three new tasks, including large-scale multi-modal registration and unsupervised inter-subject brain registration, as well as the first microscopy-focused benchmark within Learn2Reg. The new datasets also inspired new method developments, including invertibility constraints, pyramid features, keypoints alignment and instance optimisation
Snooping Helices : The elastic path finding algorithm of growing hyphae
No full textAccepté pour publication dans PNASInternational audienceHow living organisms utilize physical mechanisms to sense their environments and make informed decisions is an open question at the interface of biology and physics. In filamentous organisms like fungal hyphae, the decisions are taken by their growing tip cells and later imprinted onto the rest of the multi-cellular filament. Here we report on the growth and pathfinding of hyphae from the opportunistic fungal pathogen Candida albicans, whose ability to cross intestinal epithelial layers is associated to severe systemic infections in humans. It has been sporadically reported that C. albicans’s hyphae display helical growth inside or on top of agar gels, helicity turning in the latter case into two-dimensional oscillatory shapes. We provide an extended description of oscillatory C. albicans hyphal growth modalities, revealed under various physical confinements thanks to the use of dedicated microfluidic devices and quantitative time-lapse imaging-based analysis. These include sudden sliding events accompanied by curvature switching of the tip portion, resulting in a final oscillatory morphology of the entire filament, and stable curved tips moving against vertical microfluidic channel’s walls. These behaviors are unified under the formalism of growing squeezed helices, in which the final hyphal curved shapes result from an elastic energy minimization of a spatially confined helical portion at the tip followed by a continuous solidification front. Ultimately, the combination of our experimental results and theoretical framework provide an insight into the penetration strategy of C. albicans hyphae, which is essential for the virulence of this fungal microorganism
Color-Tunable Persistent Luminescence in Eu 2+ ,Dy 3+ ,B 3+ co-doped Sr 4 Al 14 O 25 and SrAl 2 O 4 Strontium Aluminates Ceramics for Anti-counterfeiting Applications
No full textInternational audiencePersistent luminescent (PersL) materials have garnered significant attention for applications in signaling, bioimaging, and anti-counterfeiting due to their long lasting emission after excitation stoppage. Achieving both extended afterglow durations and stable luminescence remains challenging. This study investigates the effects of crystalline composition on the PersL properties of two polycrystalline ceramics namely Sr 4 Al 14 O 25 :Eu 2+ , Dy 3+ ,B 3+ (blue-emitting, SAO-B) and SrAl 2 O 4 :Eu 2+ , Dy 3+ ,B 3+ (green-emitting, SAO-G). Through various characterization techniques such as thermoluminescence (TL), radioluminescence (RL), and photoluminescence (PL) as well as persistent luminescence (PersL) excited by different sources such as X-ray, UV and visible lights, one demonstrate that SAO-B exhibits deeper traps which offers much longer afterglow duration than SAO-G, whereas SAO-G provides higher initial emission intensity and quantum yield. By leveraging structural PersL properties in Eu 2+ ,Dy 3+ ,B 3+ co-doped compounds, colortunable emission is observed. So that various novel 'temperature resolved' and 'time resolved' anti-counterfeiting patterns are proposed, driven by the differing decay times of these two aluminates. This establishes a streamlined, scalable approach to persistent phosphor design, advancing applications in security, safety lighting, and dynamic displays.</div
Visible-Light-Mediated Radical Truce–Smiles Rearrangement via Arylazo Sulfones
No full textInternational audienceWe present a photocatalyst-free, visible-light-mediated Truce-Smiles rearrangement (TSR) for the selective difunctionalization of olefins by exploiting photoactivatable arylazo sulfones as sulfonyl radical precursors. This method efficiently affords β-sulfonyl-α-arylpropamides in high yields with excellent stereoselectivity. Furthermore, by incorporating a readily available chiral amino acid auxiliary (α-tert-butyl-leucine), we successfully developed a stereoselective variant of the TSR reaction, delivering optically enriched α-arylpropamides with excellent diastereoselectivity (up to 20:1 dr). DFT calculations provided detailed insight into the key factors governing reactivity and selectivity, particularly the contrasting behaviors of N-alkyl and N-aryl acrylamides. Overall, this work provides a sustainable and practical method for constructing sulfonylated aryl compounds under mild and catalyst-free conditions
Na2-Mn[Fe(CN)6] Prussian blue analog cathodes for Na-ion batteries – From fundamentals to practical demonstration
No full textInternational audiencePrussian blue analogues (PBAs) hold significant promise as potential cathode materials for sodium ion batteries (SIBs) due to their various merits, such as large interstitial voids enabling efficient diffusive pathways, high theoretical capacity, ease of synthesis and lower cost. However, the structural water unavoidably generated during the synthesis significantly impacts the practical applications of PBAs. While it provides structural support, it can also undergo side reactions with sodium, compromising the stability and overall performance. To address this, we here in focus on the specific role of interstitial structural water in Na2-xMn[Fe(CN)6]1-y•y•nH2O analogue, leading to the formation of hydrated H-NaMnHCF and dehydrated D-NaMnHCF. This allows us to elucidate the impact of interstitial structural water on the charge storage mechanisms in a comparative manner, using a combination of ex situ and in situ tools, including solid-state NMR, electrochemical quartz crystal microbalance (EQCM), and IR fiber-optic evanescent-wavespectroscopy (IR-FOEWS). From this gained knowledge, we elaborated a processing protocol enabling the straightforward assembly of NaMnHCF 18650 cells using hard carbon (HC) anodes, demonstrating capacities of 548 mAh and high-rate capabilities (72 % of initial capacity at 10C). We believe that this contribution is of special interest to accelerate the commercial development of NaMnHCF PBA-based SIBs
Scalable preparation of perovskite films with homogeneous structure via immobilizing strategy for high-performance solar modules
No full textInternational audienceScalable fabrication of perovskite films with homogeneous structure remains a critical challenge in bridging power conversion efficiency gap between solar modules and laboratory-scale cells. To address this, we propose a slot-die coating strategy with pyrrodiazole additives in the perovskite precursor solution to simultaneously immobilize lead iodide and formamidinium iodide. This approach enhances wet film stability by suppressing colloidal aggregation, retards the crystal growth process, and ensures a consistent growth rate across the films. These effects promote the formation of large, monolithic grains, enabling large-area perovskite films with homogeneous structure, excellent uniformity, and low defect density under ambient conditions. Using this strategy, we achieved 10 cm × 10 cm inverted perovskite solar modules with a certified efficiency of 20.3%, along with good working stability and excellent application demonstration, showcasing its great potential for industrialization
Temperature-dependent resonant inelastic X-ray scattering at Ni L3-Edge for NaNiO2 and LiNiO2
No full textInternational audienceLiNiO2 is a promising cathode material for Li-ion batteries, but its atomic and electronic structure is under debate. Indeed, two sets of Ni–O distances are identified from local structural probes that are related to either Jahn–Teller distortion or bond disproportionation of NiO6 octahedra. Moreover, LiNiO2 undergoes a monoclinic to rhombohedral transition at 200 K, the origin of which is still unclear. On the other hand, isostructural NaNiO2 shows differences from LiNiO2, as it is a well-known Jahn–Teller distorted system, and it undergoes a monoclinic to rhombohedral transition at 500 K associated with the loss of the Jahn–Teller distortion. To understand better these differences, we report herein Ni L3-edge resonant inelastic X-ray scattering experiments on LiNiO2 and NaNiO2 at different temperatures (25–520 K) and follow the spectral changes below and above the phase transition temperatures. The observed RIXS spectra and the mapping indicate strong spectral changes for NaNiO2, confirming the disappearance of Jahn–Teller distortion during phase transition, while the changes are minor for LiNiO2, suggesting very few modifications in the local structure. Theoretical simulations of RIXS spectra are required for further understanding; however, we believe that the reported data set can be a crucial resource for developing advanced simulations that are essential for deepening our understanding of the atomic and electronic structure of these nickelates