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Influence of Battery Electrode Chemistry on Electrolyte Decomposition
No full textIn rechargeable batteries a stable electrode-electrolyte interface is the key for achieving high coulombic efficiency, rate capability, and cycle lifetime. Numerous studies are published on how the electrolyte influences the interface and whether it leads to the formation of a stable solid-electrolyte-interphase (SEI) on the anode surface. However, the influence of the electrode material upon formation of the SEI has so far not been a focus. In this study, the influence of battery electrode chemistry on electrolyte decomposition is highlighted by investigating three different electrode materials in model battery systems: carbonaceous (glassy carbon), semi-conducting (silicon), and metallic (copper). Electrochemical methods including linear sweep voltammetry and chronoamperometry in combination with hard X-ray photoelectron spectroscopy are used to unravel how and in which order SEI components nucleate depending on surface material and potential. The impact of the alkali metal cation (lithium vs sodium) upon SEI formation is additionally investigated. The findings reveal that SEI formation is highly dependent on the electrode material, reduction potential, and choice of alkali cation, emphasizing its non-universal nature. These insights highlight the need for a thorough understanding of SEI formation mechanisms when designing advanced electrode materials and electrolytes for next-generation batteries
Imaging a light-induced molecular elimination reaction with an X-ray free-electron laser
No full textTracking the motion of individual atoms during chemical reactions represents a severe experimental challenge, especially if several competing reaction pathways exist or if the reaction is governed by the correlated motion of more than two molecular constituents. Here we demonstrate how ultrashort X-ray pulses combined with coincident ion imaging can be used to trace molecular iodine elimination from laser-irradiated diiodomethane (CH2I2), a reaction channel of fundamental importance but small relative yield that involves the breaking of two molecular bonds and the formation of a new one. We map bending vibrations of the bound molecule, disentangle different dissociation pathways, image the correlated motion of the iodine atoms and the methylene group leading to molecular iodine ejection, and trace the vibrational motion of the formed product. Our results provide a quantitative mechanistic picture behind previously suggested reaction mechanisms and prove that a variety of geometries are involved in the molecular bond formation
A model-agnostic likelihood for the reinterpretation of the measurement at Belle II
No full textWe recently measured the branching fraction of the decay using 362 fb of on-resonance collision data, under the assumption of Standard Model kinematics, providing the first evidence for this decay. To facilitate future reinterpretations and maximize the scientific impact of this measurement, we hereby publicly release the full analysis likelihood along with all necessary material required for reinterpretation under arbitrary theoretical models sensitive to this measurement. In this work, we demonstrate how the measurement can be reinterpreted within the framework of the Weak Effective Theory. Using a kinematic reweighting technique in combination with the published likelihood, we derive marginal posterior distributions for the Wilson coefficients, construct credible intervals, and assess the goodness of fit to the Belle II data. For the Weak Effective Theory Wilson coefficients, the posterior mode of the magnitudes , $|C_\mathrm{SL
Measurement of the CP asymmetry in decays at Belle II
No full textWe measure the CP asymmetry in decays reconstructed in collisions at the Belle II experiment using a data set corresponding to an integrated luminosity of 428 fb. A control sample of decays is used to correct for detection and production asymmetries. The result, , where the first uncertainty is statistical and the second systematic, is the most precise determination to date. It agrees with the prediction of CP symmetry from the standard model, and with results of previous measurements
Structural Heterogeneity of Proteoform-Ligand Complexes in Adenosine Monophosphate-Activated Protein Kinase Uncovered by Integrated Top-Down Mass Spectrometry
No full textAdenosine monophosphate-activated protein kinase (AMPK) is a heterotrimeric complex (αβγ) that serves as a master regulator of cellular metabolism, making it a prominent drug target for various diseases. Post-translational modifications (PTMs) and ligand binding significantly affect the activity and function of AMPK. However, the dynamic interplay of PTMs, noncovalent interactions, and higher-order structures of the kinase complex remains poorly understood. Herein, we report for the first time the structural heterogeneity of the AMPK complex arising from ligand binding and proteoforms─protein products derived from PTMs, alternative splicing, and genetic variants─using integrated native and denatured top-down mass spectrometry (TDMS). The fully intact AMPK heterotrimeric complex exhibits heterogeneity due to phosphorylation and multiple adenosine monophosphate (AMP) binding states. Native TDMS delineates the subunit composition, AMP binding stoichiometry, and higher-order structure of AMPK complex, while denatured TDMS comprehensively characterizes the proteoforms and localizes the phosphorylation site. Notably, by integrating native TDMS and AlphaFold, we elucidate a flexibly connected regulatory region of AMPK β subunit that was previously unresolvable with traditional structural biology tools. Our findings offer new perspectives on protein kinase regulation and establish a versatile framework for comprehensive characterization of proteoform-ligand complexes
Harnessing additive manufacturing-induced microstructure and solute heterogeneities for the design of precipitation-strengthened alloys
No full textSolute enrichment at lattice defects is a well-established phenomenon for promoting phase transformations. Metal additive manufacturing (AM) inherently enables this by promoting cellular structures during solidification and thermal cycling. Cellular structures exhibit compositional and lattice defect density variations between cell cores and boundaries, leading to site-specific phase-transformation (e.g., precipitation) behavior that can be selectively activated by post-AM heat treatments. Despite this potential, cellular structures have largely been treated as byproducts rather than intentionally exploited alloy design features. Guided by these insights, we designed a model Al10.5Co25Fe39.5Ni25 multi-principal element alloy to intentionally control composition and thus, precipitation driving forces across cellular structures. The alloy composition was computationally selected to promote segregation of a fast-diffusing, precipitate-forming element into the interdendritic regions during solidification in the laser powder bed fusion (PBF-LB/M) process. This segregation aligned with dislocation walls at cell boundaries, creating a “pre-conditioned” state with enhanced chemical driving force and reduced nucleation barrier for precipitation. This targeted design enabled site-specific nucleation and growth of precipitates at cell boundaries during aging. Comprehensive multiscale characterization complemented by in situ synchrotron X-ray diffraction confirmed that cellular structures accelerated precipitation, increased precipitate volume fraction and refined the precipitate size compared to the reference state where cellular structures were removed via solution annealing before aging. As a result, the alloy achieved enhanced yield strength (122.2 % increase), and improved tensile properties compared to the reference state. These findings demonstrate the potential of harnessing cellular structures as functional components to control microstructure evolution in precipitation strengthened AM alloys
Search for a new pseudoscalar decaying into a pair of bottom and antibottom quarks in top-associated production in TeV proton–proton collisions with the ATLAS detector
No full textA search for a pseudoscalar produced in association with a top-quark pair, or in association with a single top quark plus a boson, with the pseudoscalar decaying into b-quarks (), is performed using the full Run 2 data sample using a dileptonic decay mode signature. The search covers pseudoscalar boson masses between 12 and 100 GeV and involves both the kinematic regime where the decay products of the pseudoscalar are reconstructed as two standard -tagged small-radius jets, or merged into a large-radius jet due to its Lorentz boost. No significant excess relative to expectations is observed. Assuming a branching ratio , the range of pseudoscalar masses between 50 and 80 GeV is excluded at 95% confidence level for a coupling of the pseudoscalar to the top quark of 0.5, while a coupling of 1.0 is excluded at 95% confidence level for the masses considered, with the coupling defined as the strength modifier of the Standard Model Yukawa coupling
Exploring NAS for Anomaly Detection in Superconducting Cavities of Particle Accelerators
No full textThe European X-Ray Free Electron Laser is the largest particle accelerator for X-ray laser generation worldwide. To ensure a safe and efficient operation, the plant uses various monitoring systems, especially in the linear accelerator. The low-level radio frequency system has shown reliability in diagnostics, particularly in quench detection. A quench refers to a superconducting radio frequency cavity losing its superconductivity and possibly causing a downtime. The diagnostics solution, however, can be enhanced in terms of robustness and functionality. Currently, the focus is on integrating artificial intelligence to improve quench identification. Thus, a lightweight machine learning-assisted approach targeting FPGA deployment is developed. It relies on the augmentation of a physical model-based anomaly detection approach with neural network models to distinguish the quenches from the other anomalies. This paper presents the solution in which neural architecture search is applied, and elaborates on how visualizing and analyzing the anomaly detection results can provide critical insights for both short-term diagnostics and long-term pattern identification
Achieving nanosecond time resolution with a two-dimensional X-ray detector
No full textThe fastest pixel array X-ray detectors can record images with nanosecond resolution. This is accomplished by storing only a few images in in-pixel memory cells. In this study, we demonstrate nanosecond resolution over a large number of images by operating a prototype detector in an event driven mode. The performance of this mode is tested by measuring the Brownian dynamics of colloidal nanoparticles. We can achieve sub-100 ns time resolution and overcome the pixel dead time by applying a cross-correlation analysis of the neighboring pixels. The approach used in this work can be extended to study time-resolved fast processes with diffraction, scattering or imaging techniques
In situ monitoring of ligand-to-metal energy transfer in combination with synchrotron-based X-ray diffraction methods to elucidate the synthesis mechanism and structural evolution of lanthanide complexes
No full textDespite wide application of lanthanide complexes in solar cells, light-emitting diodes and sensors, their crystallization mechanisms have not been studied in detail. Further investigations of this kind can lead to the development of targeted synthesis protocols and tailoring of their structure-related physical properties. In this work, the structural evolution during the synthesis of the luminescent [Tb(bipy)2(NO3)3] (bipy = 2,2'-bipyridine) complex is studied by monitoring the ligand-to-metal energy transfer through in situ luminescence measurements combined with synchrotron-based X-ray diffraction (XRD) analysis. These experiments reveal an interesting crystallization pathway involving the formation of a reaction intermediate that is dependent on parameters such as ligand-to-metal molar ratios. In addition, the structure of [Tb(bipy)2(NO3)3] is solved from serial crystallography data collected at a microfocused synchrotron X-ray beamline. This is an emerging technique that can be used to interrogate individual crystallites and overcome beam damage effects. The resulting structure is found to correspond to that determined by classical single crystal XRD, and a perspective on realizing future in situ measurements of this type is given. This work therefore describes multiple advancements combining crystallite-specific diffraction probes and in situ techniques to track the synthesis kinetics of luminescent materials