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AI in neuroscience : the only peer-reviewed research journal dedicated to the advancement of artificial intelligence applications in neuroscience
No full textSearch for -channel scalar and vector leptoquark exchange in the high-mass dimuon and dielectron spectra in proton-proton collisions at = 13 TeV
No full textA search for t-channel exchange of leptoquarks (LQs) is performed in dimuon and dielectron spectra using proton-proton collision data collected at TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 138 fb. Eight scenarios are considered, in which up or down quarks couple to muons or electrons via a scalar or vector LQ exchange, for dilepton invariant masses above 500 GeV. The LQ masses are probed up to 5 TeV, beyond a regime probed by previous pair-production and single-production searches. The differential distributions of dilepton events are fit to templates that model the nonresonant LQ exchange and various standard model background processes. Limits are set on LQ-fermion coupling strengths for scalar and vector LQ masses in the 1–5 TeV range at 95% confidence level, establishing stringent limits on first- and second-generation LQs.[graphic not available: see fulltext
Comparing QCD+QED via full simulation versus the RM123 method: U-spin window contribution to
No full textElectromagnetic corrections to hadronic vacuum polarization contribute significantly to the uncertainty of the Standard Model prediction of the muon anomaly, which poses conceptual and numerical challenges for ab initio lattice determinations. In this study, we compute the non-singlet contribution from intermediate Euclidean current separations in quantum chromo- and electrodynamics (QCD+QED) using C boundary conditions in two ways: either non-perturbatively by sampling the joint probability distribution directly or by perturbatively expanding from an isospin-symmetric theory. This allows us to compare the predictions and their uncertainties at a fixed lattice spacing and volume, including fully the sea quarks effects in both cases. Treating carefully the uncertainty due to tuning to the same renormalized theory with N = 1 + 2 + 1 quarks, albeit with unphysical masses, we find it advantageous to simulate the full QCD+QED distribution given a fixed number of samples. This study lays the ground-work for further applications of C boundary conditions to study QCD+QED at the physical point, essential for the next generation of precision tests of the Standard Model.[graphic not available: see fulltext
Optical Absorption Properties in Pentacene/Tetracene Solid Solutions
No full textModifying the optical and electronic properties of crystalline organic thin films is of great interest for improving the performance of modern organic semiconductor devices. Therein, the statistical mixing of molecules to form a solid solution provides an opportunity to fine-tune optical and electronic properties. Unfortunately, the diversity of intermolecular interactions renders mixed organic crystals highly complex, and a holistic picture is still lacking. Here, we report a study of the optical absorption properties in solid solutions of pentacene and tetracene, two prototypical organic semiconductors. In the mixtures, the optical properties can be continuously modified by statistical mixing at the molecular level. Comparison with time-dependent density functional theory calculations on occupationally disordered clusters unravels the electronic origin of the low energy optical transitions. The disorder partially relaxes the selection rules, leading to additional optical transitions that manifest as optical broadening. Furthermore, the contribution of diabatic charge-transfer states is modified in the mixtures, reducing the observed splitting in the 0–0 vibronic transition. Additional comparisons with other blended systems generalize our results and indicate that changes in the polarizability of the molecular environment in organic thin-film blends induce shifts in the absorption spectrum
Heteromeric Completive Self-Sorting in Coordination Cage Systems
No full textHeteroleptic coordination cages, nonstatistically assembled from a set of matching ligands, can be obtained by mixing individual components or via cage-to-cage transformations from homoleptic precursors. Based on the latter approach, we here describe a new level of self-sorting in coordination cage systems, namely, ‘heteromeric completive self-sorting’. Here, two heteroleptic assemblies of type PdAB and PdAC, sharing one common ligand component A but differing in the other, are shown to coexist in solution. This level of self-sorting can be reached either from a statistical mixture of assemblies based on some ligands B and C or, alternatively, following a first step of integrative self-sorting giving a distinct PdBC intermediate. While subtle enthalpic factors dictate the outcome of the self-sorting, we found that it is controllable. From a unique set of three ligands, we demonstrate the transition from strict integrative self-sorting forming a PdABC cage to heteromeric completive self-sorting to give PdAB and PdAC by variation of the ligand ratio. Cage-to-cage transformations were followed by NMR and MS experiments. Single crystal X-ray structures for three new heteroleptic cages were obtained, impressively highlighting the versatility of ligand A to either form a π-stacked trans-figure-of-eight arrangement in PdAB or occupy two cis-edges in PdAC or only a single edge in PdABC. This study paves the way toward the control of heteroleptic cage populations in a systems chemistry context with emerging features such as chemical information processing, adaptive guest selectivity, or stimuli-responsive catalytic action
Ultrastrong and ductile NiTi-based composite with large recoverable strain mediated by a compositionally complex phase
No full textNiTi-based composites possess great potential for concurrently improving both mechanical and functional properties. However, relying on traditional alloy design principles limits the design space and greatly hinders the advancement of high-performance NiTi-based composites. The concept of high-entropy alloys has expanded the compositional landscape, unveiling unique structural characteristics for alloy design and providing new prospects for addressing these limitations. Here, we report a compositionally complex NiTi-based composite that exhibits exceptional strength and ductility, along with remarkable recoverable strain. The composite, NiTi(NbMoTaW) (at.%), comprises a 78.0 % B2 NiTi matrix, a 19.2 % Nb-Mo-Ta-W-Ti-Ni compositionally complex body-centered cubic (BCC) phase, and a small amount of Ti2Ni. Notably, this composite demonstrates an engineering compressive strength of 3274 MPa, with a compressive fracture strain of 44.2 % and a maximum recoverable strain of 7.3 % (5.6 % elastic strain and 1.7 % inelastic recoverable strain). These outstanding mechanical properties result from the unique structural characteristics of the compositionally complex phase and the lattice strain matching induced by phase transitions. The substantial recoverable strain was obtained through the reversible B2⇌R⇌B19′ phase transition. This work not only innovates a new category of high-performance NiTi-based composites but also extends the applicability of the high-entropy concept
Ordering of ionic liquids at a charged sapphire interface: Evolution with cationic chain length
No full textHypothesisRoom Temperature Ionic Liquids (RTILs) bulk's molecular layering dominates their structure also at the RTIL/sapphire interface, increasing the layer spacing with the cationic alkyl chain length n. However, the negatively-charged sapphire surface compresses the layers, increases the layering range, and affects the intra-layer structure in yet unknown ways.ExperimentsX-ray reflectivity (XR) off the RTIL/sapphire interface, for a broad homologous RTIL series 1-alkyl-3-methylimidazolium bis(trifluoromethansulfonyl)imide, hitherto unavailable for any RTIL.FindingsRTIL layers against the sapphire, exhibit two spacings:and . is n-varying, follows the behavior of the bulk spacing but exhibits a downshift, thus showing significant layer compression, and over twofold polar slab thinning. The latter suggests exclusion of anions from the interfacial region due to the negative sapphire charging by x-ray-released electrons. The layering range is larger than the bulk's. is short and near n-independent, suggesting polar moieties' layering, the coexistence mode of which with the -spaced layering is unclear. Comparing the present layering with the bulk's and the RTIL/air interface's provides insight into the Coulomb and dispersion interaction balance dominating the RTIL's structure and the impact thereon of the presence of a charged solid interface
Constraints on the Higgs boson self-coupling from the combination of single and double Higgs boson production in proton-proton collisions at = 13 TeV
No full textThe Higgs boson (H) trilinear self-coupling, , is constrained via its measured properties and limits on the HH pair production using the proton-proton collision data collected by the CMS experiment at = 13 TeV. The combination of event categories enriched in single-H and HH events is used to measure , defined as the value of normalized to its standard model prediction, while simultaneously constraining the Higgs boson couplings to fermions and vector bosons. Values of outside the interval 1.2 7.5 are excluded at 2 confidence level, which is compatible with the expected range of 2.0 7.7 under the assumption that all other Higgs boson couplings are equal to their standard model predicted values. Relaxing the assumption on the Higgs couplings to fermions and vector bosons the observed (expected) interval is constrained to be within 1.4 7.8 (2.3 7.8) at 2 confidence level
Strain engineering of CoSA-N-C catalyst toward enhancing the oxygen reduction reaction activity
No full textDeveloping efficient and cost-effective platinum-group metal-free (PGMF) catalysts for the oxygen reduction reaction (ORR) is crucial for energy conversion and storage devices. Among these catalysts, metal-nitrogen-carbon (Msingle bondNsingle bondC) materials, particularly cobalt single-atom catalysts (CoSAsingle bondNsingle bondC), show promise as ORR electrocatalysts. However, their ORR activity is often hindered by strong hydroxyl (OH) adsorption on the Co sites. While the impact of strain engineering on Msingle bondNsingle bondC electrocatalysts has been minimally explored, recent studies suggest its potential to enhance catalytic performance and optimize intrinsic activity in traditional bulk catalysts. In this context, we investigate the effect of surface strain on CoSAsingle bondNsingle bondC for ORR activity and correlate substrate-strain-induced geometric distortions with catalytic activity using experimental and theoretical methods. The findings suggest that the d-band center gap of spin states (Δεd) may be a preferred descriptor for predicting strain-dependent ORR performance in Msingle bondNsingle bondC catalysts. Leveraging CoSAsingle bondNsingle bondC moiety placed on a substrate with an average size of 1.0 μm, we achieve performance comparable to that of commercial Pt/C catalysts when used as a cathode catalyst in zinc-air batteries. This investigation unveils the structure–function relationship of Msingle bondNsingle bondC electrocatalysts regarding strain engineering and provides valuable insights for future ORR activity design and enhancement