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Bridged Ov–Ru–O–Co coordination induced by Co substitution in Co/RuO catalysts for enhanced alkaline hydrogen and oxygen evolution reactions
No full textTailoring a highly active and stable alkaline electrocatalyst endowed with an ultra-low electron transfer energy barrier for hydrogen/oxygen evolution reactions (HER/OER) has remained elusive to date. Herein, a defect-rich nanoporous Co -incorporated RuO (Co/RuO) catalyst was proposed that offered low overpotential and good stability for alkaline HER/OER. Ov–Ru–O–Co coordination under the electron coupling constructed by slight anchoring of Co at Ru sites played a pivotal role in optimizing the reaction energy barrier of the intermediates. Theoretical calculations suggested that Ov–Ru–O–Co coordination effectively optimized the primary active site by modulating the electron structure and position of the d-band center. This refinement enhanced the adsorption/desorption of reactive species, facilitating the overall progression of the catalytic reactions. Consequently, the optimal Co/RuO-1/50 catalyst achieved an ultralow overpotential at 10 mA cm , an impressive Tafel slope for both HER (26 mV, 54 mV dec ) and OER (243 mV, 88 mV dec ) and an outstanding stability for over 100 h for OER. This work offers a practical roadmap for the development of noble metal-based electrocatalysts that exhibit high activity/stability for alkaline HER/OER
Regulating Electronic Structure and Coordination Environment of Transition Metal Selenides through the High-Entropy Strategy for Expedited Lithium–Sulfur Chemistry
No full textTransition metal diselenides (TMSe) have proven as promising catalysts able to promote the conversion kinetics of lithium polysulfides (LiPSs) in lithium–sulfur batteries (LSBs). However, the limited number of catalytically active edge sites in TMSe severely hinders the realization of their full potential for boosting LSB’s performance. Herein, we report the synthesis of high-entropy NiCoMnCrVSe nanoflakes anchored on graphene supports (NiCoMnCrVSe/G) through a microwave-assisted solvothermal method. We systematically investigate how the high-entropy strategy enables the regulation of the electronic structure and coordination of various metal species in TMSe through comprehensive experimental studies and theoretical calculations. Our results show that as the number of transition metals in TMSe increases, the d-band center of metal active sites upshifts toward the Fermi level and the difference among d-band centers of various metal species diminishes, which facilitates the adsorption of LiPSs and lowers the energy barriers to nucleation/decomposition of LiS. Consequently, LSBs containing NiCoMnCrVSe/G as sulfur hosts deliver a high specific discharge capacity of 1453 mAh g at 0.1 C and excellent stability at 1 C for 500 cycles with a low decay rate of merely 0.016% per cycle. More importantly, we fabricate a ∼2.18 Ah multilayer pouch cell that can deliver an energy density of 435 Wh kg (based on the whole pouch cell weight), demonstrating the great potential of NiCoMnCrVSe/G for practical applications. This work provides important guidelines for the rational design of efficient high-entropy catalysts for bidirectional LiPSs conversion and other reactions beyond
Expected limits on the cross section of additional neutral Higgs bosons with CMS Run 3 data
No full textAdditional neutral Higgs bosons are predicted in several extensions of the Standard model.This thesis presents the expected upper limits on the production cross section times branchingratio of additional neutral Higgs bosons produced via gluon-gluon fusion and decayinginto a pair of τ leptons, derived from CMS Run 3 data. The masses of the neutral Higgsboson probed in this study range from 70 GeV to 1.2TeV. This analysis is carried out using34.75 fb−1 of proton-proton collision data from 2022 recorded at a center-of-mass energy of13.6TeV. A cut-based event selection strategy is used to suppress Standard Model backgroundcontributions and extract a signal from a narrow spin-0 resonance in the e±μ∓ finalstate. Expected limits at the 95% confidence level (CL) are inferred via a binned profilelikelihood fit. The median expected upper limits at the 95% CL range from O(10 pb) for amass of 70 GeV to O(0.1 pb) for a mass of 1.2TeV
Efficient detection of deformation-induced microstructural modifications in polycrystalline micropillars using scanning X-ray nanodiffraction
No full textMicrostructural characterization of polycrystalline micropillars remains a significant challenge, particularly under time constraints such as those encountered during in situ or other time-sensitive experimental conditions, where appropriate data checks might assist in taking the right decision and have influence on the outcome of the experiment. In this study, we present a fast and efficient method for estimating local structural properties using scanning X-ray nanodiffraction—a technique widely employed in various dynamic and static micro- and nanoscale material investigations. The analysis targets the strongest diffraction peaks within the scattering pattern to extract essential information on grain orientation, size and lattice strain, while excluding weaker signals to streamline processing. As a case study, a γ-TiAl-based micropillar (Ti–46.5Al–5Nb), fabricated via Xe+ plasma focused-ion-beam milling, was analyzed before and after 10% uniaxial compression. The micropillar's grain size significantly exceeded the X-ray beam size (∼300 nm2), and its known crystallographic orientation enabled accurate tracking of structural evolution. A direct point-to-point comparison between the undeformed and compressed states revealed localized microstructural changes associated with plastic deformation. This approach provides a rapid and reliable means of assessing microstructural evolution and demonstrates high potential for in situ and operando investigations of small-scale materials
Search for heavy long-lived charged particles with level-1 trigger scouting data from proton-proton collisions at = 13.6 TeV
No full textA search for heavy long-lived charged particles at the LHC is presented. Particles interacting with the CMS muon detector across several bunch crossings are searched for using a data sample of proton-proton collisions at = 13.6 TeV collected with the CMS detector in 2024, corresponding to an integrated luminosity of 3.7 fb. This is the first search relying on the novel level-1 trigger scouting data set collected without any trigger selection, allowing correlations between bunch crossings to be analyzed. The results are interpreted as upper limits on the cross sections of several benchmark processes with pair production of heavy long-lived charged particles. Upper limits on the fiducial cross section of a heavy long-lived charged particle with 500 GeV and 0.83 are also set in different ranges of . This analysis is a crucial proof of concept for the level-1 trigger data scouting system and complements existing searches for heavy long-lived charged particles by extending the sensitivity to lower values
XUV generation with MPC and OPCPA drivers
No full textWe measured the spectral flux of the Class 5 Moonlander high harmonic generation source for two driver systems using similar pulse parameters, but at different central wavelength: a solid state multipass cell compressed Yb laser and an optical parametric amplifier system. Both laser systems provide 17W average power at 100kHz repetition rate at comparable pulse durations, 29fs vs 20fs FWHM. Main difference is the central wavelength of 1030nm for the MPC system versus the OPCPA system with a central wavelength of 800nm. We performed high harmonic generation in with both laser systems in Argon and Krypton gas media producing broad-band XUV radiation ranging from 20 to 60 eV photon energy. Using a spectrometer and an XUV diode the spectral photon flux after filtering was determined. For both systems we could reach state-of-the-art performance with photon flux of 1e11 photons/s/eV to 1e13 photons/s/eV after filtering at the output of the light source. We will discuss the advantages and disadvantages of the different drivers for the high harmonic generation
A tunable despeckling neural network stabilized via diffusion equation
No full textThe removal of multiplicative Gamma noise is a critical research area in the application of synthetic aperture radar (SAR) imaging, where neural networks serve as a potent tool. However, real-world data often diverges from theoretical models, exhibiting various disturbances, which makes the neural network less effective. Adversarial attacks can be used as a criterion for judging the adaptability of neural networks to real data, since they can find the most extreme perturbations that make neural networks ineffective. In this work, we propose a tunable, regularized neural network framework that unrolls a shallow neural denoising block and a diffusion regularization block into a single network for end-to-end training. The linear heat equation, known for its inherent smoothness and low-pass filtering properties, is adopted as the diffusion regularization block. The smoothness of our outputs is controlled by a single time step hyperparameter that can be adjusted dynamically. The stability and convergence of our model are theoretically proven. Experimental results demonstrate that the proposed model effectively eliminates high-frequency oscillations induced by adversarial attacks. Finally, the proposed model is benchmarked against several state-of-the-art denoising methods on simulated images, adversarial samples, and real SAR images, achieving superior performance in both quantitative and visual evaluations
Probing Instantaneous Single-Molecule Chirality in the Planar Ground State of Formic Acid
No full textWe experimentally demonstrate that individual molecules of formic acid are chiral even when they are in the vibronic ground state, which has a planar equilibrium structure. We ionize the C 1 shell of the molecule and record the photoelectron in coincidence with positively charged fragments. This provides two consecutive measurements of the structure of one molecule, the first by photoelectron diffraction imaging and the second by Coulomb explosion imaging. We find that both measurements show the same handedness of the specific molecule. The phenomenon of being achiral on average but chiral at the level of individual molecules is general to prochiral molecules and is a consequence of the three-dimensional zero-point delocalization of the nuclei in the vibrational ground state
Single-shot detection of short electron bunch shapes at MHz repetition rates using diversity electro-optic scheme with advanced reconstruction algorithms at EuXFEL and FLASH
No full textTo surpass limitations in sub-picosecond electro-optic electron bunch length diagnostics[1], we present an innovative detection method utilizing diversity schemes[2]. This approach employs simultaneous multi-output measurements of the chirped optical probe modulated by the electron bunch's field. We introduce a novel inversion algorithm that automatically recognizes and compensates for imperfections in the probe laser spectrum and chirp, enabling high-fidelity retrieval of bunch shapes, particularly for broadband THz radiation over a long temporal window. Numerical simulations and initial experimental results demonstrate the system's potential for advanced, real-time bunch shape monitors at FLASH and EuXFEL, and can be extended to THz CTR or FEL based THz sources. [1] F. Sun, Z. Jiang, and X.-C. Zhang, Appl. Phys. Lett. 3, 2233 (1998) [2] E. Roussel et al., Light: Science & Applications 11, 14 (2022
