European Synchrotron Radiation Facility

Tetragonal tungsten bronzes are normally uniaxial ferroelectrics making crystallographic texture pivotal for optimization of electrical properties. Sr x Ba 1-x Nb 2 O 6 (SBN), x=0.4, 0.5 and 0.6, thin films with out-of-plane (001) or in-plane (310) oriented polarization were deposited by aqueous chemical solution deposition on SrTiO 3 (STO)(100) substrates. A texture degree of >90% was achieved for (001) oriented SBN films on SrO terminated STO, while the (310) oriented films on TiO 2 terminated STO possessed a degree of texture >50%. The films were in compression compared to bulk due to epitaxial strain, thermal strain, and a reduced lattice parameter of the film due to Ti-doping, all related to the substrate used. The Curie temperature of selected (001) oriented films showed the expected decrease with increasing Sr content, and additional decrease attributed to Ti-doping. A piezo response was measured in (001) oriented films by in situ application of an electrical field during X-ray diffraction measurements.

The welding of dissimilar metallic assemblies produced by high-velocity impact occurs at high strain rates ( i.e. , impact velocities) and various dynamic collapsing angles. However, the quality of the resulting weld surface depends on several parameters, one of which is the jet formation and particle cloud formation upon impact. This phenomenon arises from intense heat and pressure upon impact, playing a decisive role in determining the resulting weld quality. Here, the jet formation of such welds is described, providing new insights into the understanding of cold-welding methods. Jet formation plays a key role in generating the necessary conditions required to weld two dissimilar metal surfaces. Copper (Cu) and aluminum (Al) samples were subjected to high strain-rate loading using the single-stage gas gun available at ID19 beamline (ESRF, France) coupled with ultra-fast synchrotron X-ray radiography in order to investigate, in situ , the production, propagation, and evolution of jets upon impact of dissimilar metals. Several impact conditions (impact angle and material configuration) were investigated at an approximate impact velocity of 500 m/s. The results reveal that the jet size, speed, and morphology evolve differently as a function of the initial impact conditions. These results demonstrate, for the first time, a direct in situ investigation of jet dynamics and weld quality in impact welding of dissimilar metallic materials. • Synchrotron X-ray imaging reveals jet dynamics in dissimilar metal impacts. • Impact angle strongly influences jet morphology and propagation behavior. • Flyer–target material configuration controls jet angle and jet velocity. • Jet growth shows a linear relationship between jet length and time.

The proline-rich domain (PRD) of the tumor suppressor p53 plays a central role in modulating conformational dynamics and molecular interactions, yet its intrinsic structural behavior remains incompletely understood. Here, we combine extensive all-atom molecular dynamics simulations with biophysical validation to characterize the conformational ensemble of the p53 PRD. The domain behaves as an intrinsically disordered region, sampling a highly heterogeneous ensemble with average end-to-end distance and radius of gyration of 52.5 Å and 21.8 Å, respectively. Despite this disorder, transient local structure is prominent: unordered conformations dominate, followed by substantial polyproline II (PPII) content, with β-bends and turns linking conserved PXXP motifs. Circular dichroism and small-angle X-ray scattering experiments corroborate the largely disordered yet partially structured nature of the PRD. Ramachandran and contact analyses reveal that consecutive prolines, particularly Pro71-Pro72, impose steric constraints that stabilize locally extended conformations and restrict backbone collapse. To approximate the PRD within full-length p53, additional simulations were performed with restrained terminal distances, yielding reduced conformational variability and improved agreement with small-angle X-ray scattering data while preserving secondary-structure propensities. PPII helices emerge as particularly robust features, acting as stiff spacers linking the transactivation domain to downstream regions. Finally, simulations of clinically relevant variants reveal mutation-specific local perturbations: P72R disrupts consecutive proline rigidity and increases flexibility, whereas P82L abolishes a PXXP motif and its associated PPII helix. These results identify proline-mediated rigidity and transient PPII structure as key determinants of the dynamic conformational landscape of the p53 PRD.

Characterizing nanoparticles in terms of size and morphology is essential to understand their physical and optical properties. Small or Ultra Small-Angle X-ray Scattering (SAXS/USAXS) is a powerful in situ technique that allows the analysis of such nanostructures exhibiting size and morphology through the Guinier and Porod regimes, which can be repeated at different scales (e.g., primary spheres and Agglomerates for mass fractal agglomerates, as focused on in this study). This is the principle of the widely used Beaucage’s unified model, built in reciprocal q -space (the momentum transfer or scattering wave vector) in order to interpret experimental results. An alternative method based on pair correlation modeling can be used. Indeed, by definition, the scattered signal corresponds to the Fourier transform of the particles’ pair correlation function. The present study compares the two approaches for fractal agglomerates of point-contact spheres. It is shown that the Beaucage’s model is limited to agglomerates consisting of a large number of primary spheres and that certain destructive interferences, not taken into account in this model, can affect data inversion, potentially affecting the extraction of the primary sphere size distribution. In this work, both models are compared in the direct way applied on synthetic data, and used to invert experimental SAXS data from soot particles in a laminar ethylene diffusion flame measured at the European Synchrotron Radiation Facility (ESRF) and processed via Abel inversion. This study puts in evidence the fundamental differences between both models and highlight their respective limitations. Nevertheless, both models provide similar results except for the mass fractal dimension and primary sphere geometric standard deviation. The present study demonstrates thus the potential of the pair correlation modelling and encourages its further development. • A critical analysis and comparison is carried out between unified scaling approaches, commonly used in interpreting electromagnetic wave scattering signals in visible or X-ray ranges, and a more rigorous method based on modeling the pair correlation function. • The results highlight a significant shortcomings in classical modeling, particularly its neglect of destructive interference effects that crucially influence the amplitude and slope of modeled signals. • A new expression for the polydispersity index (PDI) tailored for lognormal distributions is introduce. • The application of Abel inversion to scattering spectra in laminar diffusion flames has a strong impact on inverted parameters. • Applying both models to experimental data obtained by small-angle X-ray scattering (SAXS) reveals significant impacts on most of the measured parameters when the new expression for PDI is taken into account.

Platinum and its alloys remain the state-of-the-art catalysts for selective nitric oxide production via ammonia oxidation. Yet improving efficiency, selectivity, and stability is a century-old challenge. Operando diffraction techniques are combined with mass spectrometry to investigate structural dynamics of ensemble and single α -Al 2 O 3 -supported Pt crystalline particles under realistic reaction conditions. Only by switching from ensemble averaging methods such as surface X-ray diffraction to single-particle sensitive Bragg coherent diffraction imaging can we identify distinct strain and morphology responses between particle types. Large and elongated particles exhibit annealing-induced misfit strain and a stable morphology during the reaction, while smaller, round, and low-strain particles display surface roughening and defect evolution at 400 °C, coinciding with enhanced NO selectivity. Notably, NH 3 exposure at 600 °C reverses facet strain. These findings highlight the critical role of nanoscale strain and morphology in catalyst performance and demonstrate the power of multi-techniques operando approaches to guide the design of next-generation catalytic materials. • Operando BCDI tracks strain evolution in single Pt nanoparticles during NH 3 oxidation. • Oxygen-rich and ammonia-rich regimes induce distinct defect and strain behaviors. • Structural response varies across particles, highlighting heterogeneity. • Strain in Pt nanoparticles evolve during NH 3 exposure at 600 °C. • Defect formation correlates with catalytic selectivity between NO and N 2 .

Actinide systems continue to raise many unanswered questions on topics involving the number of electrons in valence states, the degree of f-electron localisation, and the character of their chemical bonding. Their partially filled 6d and 5f valence shells are responsible for most of their complex behaviour. Understanding the intricate electronic structure of actinides requires the use of advanced experimental and theoretical techniques. Among the experimental approaches, resonant inelastic X-ray scattering (RIXS) and X-ray absorption near edge structure (XANES) in the high energy resolution fluorescence detection (HERFD) mode at the actinide M4,5 edges have proven to be powerful techniques for investigating their electronic structure. Here, we review the fundamentals of these X-ray spectroscopies and the theoretical advances in electronic structure calculations using data recorded on 5f electron systems at the An M4,5 edges (An = Th, U, Np, Pu).

Ultrafast control of functional materials by light is key for developing optoelectronic devices. Still, the mechanisms by which microscopic photoinduced excitations evolve into a macroscopic phase transformation remain poorly understood, partly due to the experimental challenges of isolating multiscale electronic and structural dynamics. Here we use femtosecond X-ray techniques to track the non-equilibrium dynamics leading to macroscopic transformation in a ferroelastic charge-transfer Prussian blue analogue. The experimental data evidence a sequence of phenomena. The initial electronic excitation leads to reverse Jahn-Teller distortion within 50 fs, causing intermetallic charge-transfer polarons within 200 fs. Polarons generate considerable lattice strain and trigger phase nucleation within 60 ps. This elastically driven cooperativity, launched by the photoinduced polarons, offers an efficient route to the generation and stabilization of photoinduced phases in many volume-changing materials.

Protein crystals are intrinsically hydrated systems, and their structural integrity is strongly influenced by environmental humidity. Understanding the effects of relative humidity (RH) variation on crystal stability is therefore essential for both fundamental research and applied studies. In this work, the structural response of tetragonal hen egg-white lysozyme (HEWL) to controlled RH variation was investigated using in situ X-ray powder diffraction (XRPD). Polycrystalline HEWL samples were subjected to systematic gradual dehydration and rehydration cycles, as well as to non-gradual RH variation protocols. Pawley analysis of the XRPD data enabled monitoring of the evolution of unit cell parameters and unit cell volume as a function of RH. Under all experimental conditions, the tetragonal polymorph (space group P43212; a = 79.105 (4) Å, c = 38.231 (2) Å) was preserved. RH variation induced smooth, continuous and anisotropic lattice changes, characterized by a decrease in the a (=b)-axis and a concomitant increase in the c-axis upon dehydration, while rehydration resulted in the opposite behavior. The overall magnitude of lattice variation remained limited (within ±2%), indicating a high degree of structural stability. Partial degradation of crystallinity was observed only after prolonged exposure to low RH levels. These findings demonstrate the remarkable structural resilience of tetragonal HEWL and highlight the effectiveness of in situ XRPD as a powerful tool for probing hydration-driven lattice responses in protein crystals under realistic environmental conditions.

The middle Permian represents a critical interval in therapsid evolution, when gorgonopsians emerged as some of the first specialized apex predators within terrestrial ecosystems. Despite their significance, the early diversification of Gorgonopsia in Gondwana remains poorly understood due to scarcity and fragmentary material. Here, we describe a nearly complete skull (BP/1/8260) with an occluded lower jaw from the lower Abrahamskraal Formation (Tapinocephalus Assemblage Zone). The specimen exhibits a distinctive combination of cranial features, including a transversely narrow snout, small orbital and temporal openings, V-shaped palatine bosses, and a vertically oriented occiput that distinguish it from all known gorgonopsians. Based on its unique morphology, a new taxon, Jirahgorgon ceto sp. nov., is established for this specimen. In our phylogenetic analysis, the new taxon forms a clade with Phorcys dubei, which is here named Phorcyidae fam. nov. Members of Phorcyidae are unique among basal African gorgonopsians in combining a vertical occiput and rubidgeine-like cranial proportions, indicating that large-bodied gorgonopsians were present in the Wordian and overturning notions that they were exclusively small carnivores until the Wuchiapingian. Basal skull length analyses indicate that body size evolution in Gorgonopsia, while largely random through time (Brownian motion evolutionary model), is nonetheless structured by shared ancestry. The discovery of Jirahgorgon illustrates the complexity of gorgonopsian evolution, showing an early appearance of large-bodied, robust morphotypes and highlighting the lower Abrahamskraal Formation as a key resource for understanding the initial radiation of theriodonts.

Solid–solid phase change materials (SS-PCMs) are attractive candidates for thermal energy storage (TES) owing to their intrinsic shape stability, yet their widespread application remains limited by the lack of design rules linking the molecular structure to phase-transition properties. Here, we present a comprehensive study of layered hybrid chlorometallates, (CnH2n+1NH3)2MCl4 (M = Cu, Mn, Zn; n = 6–16), as tunable SS-PCMs. For that, 15 compounds (M = Cu, Mn, Zn; n = 6, 7, 12, 13, 16) were prepared, and their low-temperature (LT) forms were studied by single-crystal XRD and vibrational spectroscopies. By a multitechnique approach, involving calorimetry, temperature-dependent infrared, and Raman spectroscopies, and combined in a single synchrotron experiment temperature-dependent X-ray absorption spectroscopy (XAS), total scattering/Pair Distribution Function (PDF), and powder XRD (PXRD) analyses, we evidenced the impact of both parameters (M and n) not only on the LT structures but also on the thermal properties and on the high-temperature (HT) structures. Especially, we evidenced that although materials based on octahedrally (here Mn and Cu) and tetrahedrallly (here Zn) coordinated cations share many common features in their LT forms (alternating organic–inorganic layered structures, alkylammonium chains parallel to each other, and supramolecular organic–inorganic interactions of the same nature and strength), their HT phases strongly differ, especially at a medium range distance. This comprehensive study is not only of fundamental interest but will also help to address questions, such as the shaping and mechanical integrity of these SS-PCMs upon thermal cycling that need to be answered prior to their integration into practical devices for next-generation TES.