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Soft mode induced structural phase transition in BaZnTeO at high pressure
No full textIn this paper, we present a thorough investigation of vibrational, structural, and electronic properties of perovskite-type rhombohedral BaZnTeO (BZTO) under systematic application of pressure. To carry out the analysis, we have performed pressure-dependent Raman spectroscopic measurements, synchrotron x-ray diffraction, and density functional theory (DFT)-based calculations. At ambient conditions, BZTO stabilizes in space group, which under pressure undergoes a structural transition to a monoclinic phase with space group 2/ at around 18 GPa. In-depth Raman analysis reveals softening of a phonon mode E (∼28cm) leads to the structural phase transition. First-principles DFT calculations also indicate that the doubly degenerate soft mode associated with the in-phase TeO6 octahedral rotation drives the structure to a lower symmetry phase 2/
Influence of Ion Size on Structure and Redox Chemistry in Na‐Rich and Li‐Rich Disordered Rocksalt Battery Cathodes
No full textLi-rich disordered rocksalts are promising next-generation cathode materials for Li-ion batteries. Recent reports have shown it is also possible to obtain Na-rich disordered rocksalts, however, it is currently poorly understood how the knowledge of the structural and redox chemistry translates from the Li-rich to the Na-rich analogs. Here, the properties of Li2MnO2F and Na2MnO2F are compared, which have different ion sizes (Li+ = 0.76 vs Na+ = 1.02 Å) but the same disordered rocksalt structure and stoichiometry. It is found that Na2MnO2F exhibits lower voltage Mn- and O-redox couples, opening access to a wider compositional range within the same voltage limits. Furthermore, the intercalation mechanism switches from predominantly single-phase solid solution behavior in Li2MnO2F to a two-phase transition in Na2MnO2F, accompanied by a greater decrease in the average Mn─O/F bond length. Li2MnO2F retains its long-range disordered rocksalt structure throughout the first cycle. In contrast, Na2MnO2F becomes completely amorphous during charge and develops a local structure characteristic of a post-spinel. This amorphization is partially reversible on discharge. The results show how the ion intercalation behavior of disordered rocksalts differs dramatically when changing from Li- to Na-ions and offers routes to control the electrochemical properties of these high-energy-density cathodes
Unlocking atom-specific radiotherapy – DNA backbone breakage caused by X-ray photoactivation
No full textThe effectiveness of radiation therapy can be enhanced by understanding the fragmentation mechanisms of iodine-doped DNA oligonucleotide under tender X-rays, as explored experimentally and computationally in our study. By primarily targeting iodine atoms above their L-edge ionization energies, we observed a significant increase in the production of fragments critical to DNA backbone breakage, particularly within mass ranges associated with phosphate and sugar groups. The mass spectroscopy experiments demonstrated that iodine-doped DNA oligonucleotides undergo intense fragmentation at long distances from the initial photoactivation site. Born–Oppenheimer based molecular dynamics simulations confirmed the generation of numerous small fragments, including reactive oxygen species, which are pivotal in enhancing the radiation damage. These findings highlight the effectiveness of iodine doping in amplifying DNA damage in radiotherapy via iodine photoactivation, thereby improving the potential for targeted cancer treatment
CO Versus CH Aggregation on Trifluorobenzene: Molecular Level Characterization via Rotational Spectroscopy
No full textThe cluster growth behavior of CO and CH on an aromatic ligand has been studied through the unambiguous identification of complex structures of 1,2,3-trifluorobenzene-(CO)1–4 and -ß(CH4)1–2 using broadband rotational spectroscopy in conjunction with extensive theoretical calculations. The results reveal a contrast in the thermodynamically favorable ligand-gas binding sites and noncovalent interactions of the two gaseous molecules on the ligand. The observation of a tunneling splitting and large centrifugal distortions indicates that CH molecules bind to the fluorinated π system via three weak hydrogen bonds without CH self-interactions, resulting in an effective structure displaced toward the dissociation limit. Conversely, CO shows diverse and stronger intermolecular interactions with the fluorinated benzene, including F─C tetrel bonding, lone pair to π-hole interactions, stacking, and a significant contribution from CO self-interactions. The thorough examination of ligand–gas interactions and aggregation patterns highlights the significant capacity and selectivity of the fluorinated aromatic ligand for accepting CO over CH
Decay-mode independent searches for new light scalars at future Higgs factories
No full textThe existence of Higgs-like scalars, which could be produced atelectron-positron collider in association with a Z boson, is predictedby many BSM models and, assuming a smallcoupling to the Z boson, still not excluded by experimental data.Prospects for discovering such an scalar at future Higgsfactories have been studied by different methods.The most model-independent one is based on the recoil of the newparticle against the Z, since this is independent of the decay modes of the new scalar.Based on this method, searches were performed for any mass of thescalar and for two different decays of the Z boson, to a pair ofmuons and to a pair of electrons. The combination of the limits obtainedby the two Z decay modes was also performed.For detector-level simulations, the study takes the ILD detector conceptand ILC parameters at 250 GeV as example. Full simulated background sampleswere used by the study, while for signal samples the SGV fast simulation,adapted to the ILD, was used for detector simulation and high-level reconstruction
A - BCD dualities
No full textIn this paper we propose 4d and 3d dualities among special unitary gauge theories with fundamentals and antisymmetric flavors and symplectic or orthogonal gauge theories with fundamentals and two index tensor matter.The various dualities originate from a conjectured 4d self-duality for with an antisymmetric and four fundamental flavors. While we provide a proof of such self duality for , we focus on baryonic deformations for the cases at higher ranks. The deformations give rise to RG flows, deforming the self duality into new types of dualities, involving and gauge theories, where the precise value of depends on the baryonic deformation. We provide strong checks on the validity of these dualities, by proving the integral identities among their superconformal index. By dimensional reduction on a circle, real mass flows and other deformations we then find a rich set of new dualities 3d.These dualities are first conjectured from localization, by the application of the duplication formula for the one loop determinants of the matter fields, and then they are proved by using the tensor deconfinement technique
Exploratory calculation of the rare hyperon decay Σ → pℓℓ from lattice QCD
No full textThe rare hyperon decay Σ → pℓℓ is a flavour-changing neutral current process mediated by an s → d transition that occurs only at loop level within the Standard Model. Consequently, this decay is highly suppressed, making it a promising avenue for probing potential new physics. While phenomenological calculations have made important progress in predicting the decay amplitude, there remains a four-fold ambiguity in the relevant transition form factors that prevents a unique prediction for the branching fraction and angular observables. Fully resolving this ambiguity requires a first-principles Standard-Model calculation, and the recent observation of this process using LHCb Run 2 data reinforces the timeliness of such a calculation. In this work, we present the first lattice-QCD calculation of this decay, performed using a 2+1-flavour domain-wall fermion ensemble with a pion mass of 340 Mev. At a small baryon source-sink separation, we observe the emergence of a signal in the relevant baryonic four-point functions. This allows us to determine the positive-parity form factors for the rare hyperon decays from first-principles, albeit with large statistical and systematic uncertainties
Outside Front Cover: Synthesis of Gold Hydride at High Pressure and High Temperature (Angew. Chem. Int. Ed. 38/2025)
No full textGold compressed in the presence of a hydrocarbon hydrogen source was heated with an X-ray free electron laser in a pump-probe experiment. Above 40 GPa and 2200 K, it reacts to form hexagonal gold hydride. The hydrogen is superionic in the gold lattice and diffuses freely. Gold is usually known as an unreactive metal, and its enhanced reactivity under extreme conditions points to modifications to chemistry in this regime, as explained by Mungo Frost et al. in their Research Article (e202505811). Image by Greg Stewart/SLAC National Accelerator Laboratory
3D reconstruction and corrosion resistance of porous Zr-Al intermetallic via thermally-regulated rapid self-exothermic reaction
No full textFor environmental management purposes, industrial alkaline waste streams are essential to be filtered effectively. Here, porous Zr-Al intermetallic compounds were prepared using a rapid self-exothermic reaction with a preventative holding treatment. The pre-heating treatment for thermal-adjustment accelerates the solid-state diffusion kinetics and reduces the heat released by the thermal explosion reaction (TE). The porous Zr-Al compounds were structurally reconstructed using the 3D X-ray microscopy (3D-XRM) technique, through which the porosity, pore connectivity, and permeability properties were semi-quantitatively analyzed in conjunction with the reconstructed model. In-situ high-temperature synchrotron X-ray diffraction (HT-SXRD) was employed to reveal the phase constitution evolution as a function of temperature, underpinning the effectiveness of the pre-heating treatment and revealing the formation of thermo-dynamically stable intermetallic phases. The complete reaction between Zr and Al is facilitated by the pre-heating treatment, producing a homogeneous pore-skeleton structure and inhibiting microcrack formation with superior connectivity and permeability properties. Consequently, optimal sample 570/700 shows excellent filtering properties due to the uniformly distributed and inter-connected pores. The superior corrosion resistance further evidences the expedited passivation film formation, combining with the homogeneous pore structure and stable intermetallic composition, which altogether improves substrate protection and mitigates electrochemical degradation processes. The structure-function integrated porous Zr-Al provides a meaningful path and shows the potential for filtration applications of industrial wastewater/gas
Tau leptons as a tool to investigate the CP properties of the Higgs boson at CMS
No full textAmong the Higgs boson decay channels, the one to tau leptons can offer insight into the properties of the Higgs boson. The structure under CP symmetry of the tau Yukawa coupling was investigated in CMS by reconstructing the decay planes of the two tau leptons and measuring their angular separation. Tau decay planes are reconstructed depending on the studied decay channel to take advantage of the correlation between the tau lepton spin and the momenta of its decay products. Using the data collected during the LHC Run 2 data-taking period, the study revealed that the Yukawa coupling is largely dominated by a pure CP-even component. A pure CP-odd Yukawa coupling is excluded with a 99.7% confidence level allowing to constrain the allowed phase space for possible BSM scenarios