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Nucleotide-bound crystal structures of the SARS-CoV-2 helicase NSP13
No full textNucleotide-bound crystal structures of SARS-CoV-2 NSP13 in ADP- and ATP-bound states were resolved to 1.8 and 1.9 Å, respectively. The ADP-bound model captures a state immediately following ATP hydrolysis, with both ADP and orthophosphate still present in the active site. Further comparative analysis revealed that crystal packing influences NSP13 by stabilizing the nucleotide-binding site, underscoring the importance of accounting for these effects in structure-based drug design targeting NSP13
Search for a Dark Higgs Boson Produced in Association with Inelastic Dark Matter at the Belle II Experiment
No full textInelastic dark matter models that have two dark matter particles and a massive dark photon can reproduce the observed relic dark matter density without violating cosmological limits. The mass splitting between the two dark matter particles χ1 and χ2, with m(χ2)>m(χ1), is induced by a dark Higgs field and a corresponding dark Higgs boson h′. We present a search for dark matter in events with two vertices, at least one of which must be displaced from the interaction region, and missing energy. Using a 365 fb-1 data sample collected at Belle II, which operates at the SuperKEKB e+e- collider, we observe no evidence for a signal. We set upper limits on the product of the production cross section σ(e+e-→h′χ1χ2), and the product of branching fractions B(χ2→χ1e+e-)×B(h′→x+x-), where x+x- indicates μ+μ-,π+π-, or K+K-, as functions of h′ mass and lifetime at the level of 10-1 fb. We set model-dependent upper limits on the dark Higgs mixing angle at the level of 10-5 and on the dark photon kinetic mixing parameter at the level of 10-3. This is the first search for dark Higgs bosons in association with inelastic dark matter
Fast Sodium Ion Conductivity in Pristine NaSnP : Synthesis, Structure and Properties of the Two Polymorphs LT‐NaSnP and HT‐NaSnP
No full textAchieving high ionic conductivities in solid state electrolytes is crucial for the development of efficient all-solid-state-batteries. Considering future availability and sustainability, sodium materials hold promises for an alternative for lithium materials in all-solid-state batteries, due to the higher abundance. Here, we report on a sodium phosphide ion conductor NaSnP with a conductivity of 0.53 mS cm at room temperature as a pristine material. Due to the simple tetrahedral SnP structure units, NaSnP has potential for optimization through aliovalent substitution as successfully applied in sulfide-based materials. NaSnP is easily accessible from exclusively abundant elements and forms a high- and low-temperature polymorph, which further allows for a fundamental understanding of the structure-property relationship. Both polymorphs are structurally characterized by synchrotron X-ray powder diffraction and MAS–NMR spectroscopy. Ion conductivity and activation energy for ion mobility is determined by temperature dependent impedance spectroscopy and static Na-NMR measurements. Both MEM analysis of scattering densities as well as structure determination by Rietveld methods hint for ionic motion between special Na positions in the structure and that ion migration proceeds along pathways passing triangular faces of neighboring tetrahedral and octahedral voids. The specific voids filling in the disordered HT-phase are found to be a crucial parameter for ion migration
Pulmonary delivery of anti-infectives from natural sources: Development and characterization of liposomal sanggenon formulations
No full textSanggenon C (SGC) and sanggenon D (SGD) are stereoisomeric natural products with promising anti-infective potential, especially against pathogens involved in acute respiratory infections. However, their bulky structures, poor aqueous solubility, and low oral bioavailability present major therapeutic challenges. Inhalation enables direct delivery to the site of infection while minimizing systemic exposure. Liposomal formulations DMPC:DMPG (2:1 w/w) of SGC and SGD, prepared via ethanol injection, achieved high drug loadings (> 3.5 mg/mL). Drug-lipid interactions were evaluated via DSC, Langmuir trough studies, SAXS, and cryo-TEM, showing incorporation of the compounds in the lipid bilayer. While stereochemistry-dependent differences were evident in vesicle size and thermotropic behavior, other biophysical data indicated that these differences were largely mitigated upon formulation. Liposomal formulations showed an excellent stability during nebulization with a vibrating mesh nebulizer (mass median aerodynamic diameters: 1.30–1.35 µm) and the high affinity of the compounds for the lipid bilayer resulted in a sustained in vitro release profile (8–9 % after 240 h). The retention of the drugs in the liposomes also significantly reduced cytotoxicity at 24 h compared to neat compounds. These findings highlight the importance of stereochemistry in drug-membrane interaction, yet their similar formulation performance suggests that both compound formulations are promising candidates for pulmonary anti-infective therapy
Search for a heavy pseudoscalar Higgs boson decaying to a 125 GeV Higgs boson and a Z boson in final states with two tau and two light leptons in proton-proton collisions at TeV
No full textA search for a heavy pseudoscalar Higgs boson, A, decaying to a 125 GeV Higgs boson h and a Z boson is presented. The h boson is identified via its decay to a pair of tau leptons, while the Z boson is identified via its decay to a pair of electrons or muons. The search targets the production of the A boson via the gluon-gluon fusion process, gg → A, and in association with bottom quarks, . The analysis uses a data sample corresponding to an integrated luminosity of 138 fb collected with the CMS detector at the CERN LHC in proton-proton collisions at a centre-of-mass energy of TeV. Constraints are set on the product of the cross sections of the A production mechanisms and the A → Zh decay branching fraction. The observed (expected) upper limit at 95% confidence level ranges from 0.049 (0.060) pb to 1.02 (0.79) pb for the gg → A process and from 0.053 (0.059) pb to 0.79 (0.61) pb for the process in the probed range of the A boson mass, m, from 225 GeV to 1 TeV. The results of the search are used to constrain parameters within the benchmark scenario of the minimal supersymmetric extension of the standard model. Values of tan β below 2.2 are excluded in this scenario at 95% confidence level for all m values in the range from 225 to 350 GeV.[graphic not available: see fulltext
Agent-based code generation for the Gammapy framework
No full textSoftware code generation using Large Language Models (LLMs) is one of the most successful applications of modern artificial intelligence. Foundational models are very effective for popular frameworks that benefit from documentation, examples, and strong community support. In contrast, specialized scientific libraries often lack these resources and may expose unstable APIs under active development, making it difficult for models trained on limited or outdated data. We address these issues for the Gammapy library by developing an agent capable of writing, executing, and validating code in a controlled environment. We present a minimal web demo and an accompanying benchmarking suite. This contribution summarizes the design, reports our current status, and outlines next steps
Search for periodic variability in γ-ray blazars Using Fermi -LAT
No full textBlazars are known to exhibit variability across a broad range of time-scales. This behaviour can include periodicity in theirγ -ray emission, whose clear detection remains an ongoing challenge, partly due to the inherent stochasticity of the processesinvolved and also the lack of adequately well-sampled light curves. In this study, we perform a systematic search for periodicityin a selected sample of 24 γ -ray blazars using twelve years of Fermi-LAT data. The sample comprises the most promisingcandidates selected from a previous study, extending the light curves by three additional years, expanding the analysed energyrange from >1 to >0.1 GeV to improve photon statistics, and enhancing the time-series analysis methodology. We incorporateupper-limit flux points in the analysis rather than discarding them, thereby preserving the temporal structure in the light curves. Asuite of seven complementary time-series analysis methods is employed to ensure statistical robustness, including autoregressivemodels, representing a methodological advancement over the prior work. A further improvement is the explicit estimation of thelook-elsewhere effect, which allows us to assess the global significance of any detected signals. The study is also supported byadditional statistical treatments employed to minimize false detections and strengthen the reliability of the results. Our analysisreveals a hint of periodicity in PG 1553+113 with a global significance of ≈ 1.8σ. For the remaining sources in the sample,the re-evaluation of previously reported periodicities indicates that they are statistically consistent with arising from stochasticvariability
Non-van der Waals superlattices of carbides and carbonitrides
No full textArtificial superlattices, constructed from atomic layers such as graphene using layer-by-layer periodic stacking or sequential epitaxial growth, have emerged as a versatile platform for developing new materials with properties surpassing the existing materials1,2,3. However, the explored superlattices are predominantly van der Waals (vdW) superlattices, constrained by weak interface coupling4,5. Here we present an efficient synthetic protocol that achieves a family of non-vdW superlattices of carbides and carbonitrides, featuring hydrogen bonding between layers through a stiffness-mediated rolling-up strategy. The crucial step involves customizing the bending stiffness of the atomic layers derived from MAX phases by creating metal vacancies in MX slabs, triggering their ordered rolling-up under rapid flexural deformation. Unlike vdW superlattices, our non-vdW superlattices with hydrogen bonding afford robust interlayer electronic coupling with highly concentrated charge carriers (1022 cm−3). Consequently, our superlattices exhibit a notable electrical conductivity of about 30,000 S cm−1, which is around 22 times that of the counterparts. When used in electromagnetic interference shielding, the optimal non-vdW superlattice film demonstrates a remarkable shielding effectiveness of 124 dB, surpassing that of any known synthetic materials with comparable thickness. The non-vdW superlattices are anticipated to markedly broaden the material platform, offering variable compositions and crystal structures for new developments in artificially stacked systems
Compactification on Calabi-Yau threefolds: consistent truncation to pure supergravity
No full textWe study compactifications of eleven- and ten-dimensional maximal supergravity on Calabi-Yau threefolds. We explicitly construct truncations to pure supergravity with eight supercharges in five and four dimensions and show that they are consistent, i.e. that every solution of the lower-dimensional equations of motion fully solves the higher-dimensional ones. We furthermore match the supersymmetry transformations and demonstrate the consistency to full non-linear order in fermions. Our construction is independent of the choice of Calabi-Yau threefold and only involves the universal structures such as the Kähler form and the holomorphic three-form, in agreement with implicit constructions in the generalised geometry literature. As an immediate application, we embed four-dimensional extremal black holes in the higher-dimensional supergravities. We furthermore propose Ansätze for consistent truncations on all universal structures, leading to supergravities with additional matter multiples. An extensive list of equations of motion and supersymmetry transformations for various supergravity theories is provided in the appendix
Octave-Spanning Soliton Microcomb with Over 50% Conversion Efficiency Enabled by Strong Mode Coupling
No full textDissipative Kerr solitons (DKS), which provide coherent and stable frequency combs, have emerged as a powerful tool for a wide range of applications in metrology, spectroscopy, telecommunications [1]. However, one of the major challenges hindering their practical deployment is the inherently low pump-to-comb conversion efficiency [2], [3], which is typically restricted to only a few percent. Recent advances have introduced promising strategies to enhance conversion efficiency in single-soliton states, including new pumping schemes such as pulsed pumping [4] and novel cavity designs like photonic molecules [5]. Nevertheless, existing high-efficiency demonstrations have thus far been constrained by limited optical bandwidths, falling short of the broad spectral coverage required for demanding applications such as self-referencing and broadband spectroscopy