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Measurement of the inclusive WZ production cross section in pp collisions at = 13.6 TeV
No full textThe inclusive WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy of 13.6 TeV, using data collected during 2022 with the CMS detector, corresponding to an integrated luminosity of 34.7 fb. The measurement uses multileptonic final states and a simultaneous likelihood fit to the number of events in four different lepton flavour categories: eee, eeμ, μμe, and μμμ. The selection is optimized to minimize the number of background events, and relies on an efficient prompt lepton discrimination strategy. The WZ production cross section is measured in a phase space defined within a 30 GeV window around the Z boson mass, as σ (pp → WZ) = 55.2 ± 1.2 (stat) ± 1.2 (syst) ± 0.8 (lumi) ± 0.3 (theo) pb. In addition, the cross section is measured in a fiducial phase space closer to the detector-level requirements. All the measurements presented in this paper are in agreement with standard model predictions.[graphic not available: see fulltext
A critical residue in a conserved RBD epitopethe determines neutralization breadth of pan-sarbecovirus antibodies with recurring YYDRxxG motifs
No full textThe emergence of pandemic coronaviruses remains a global health concern, highlighting the need for broadly neutralizing antibodies (bnAbs) that can target multiple sarbecoviruses. In this study, we isolated and characterized a novel antibody, pT1679, that demonstrates exceptional neutralization breadth. The antibody prevented infection with SARS-CoV-2 variants of concern, such as Omicron BA.1, and effectively neutralized pseudotyped viruses displaying S proteins from many SARS-CoV-2 variants and various bat and pangolin sarbecoviruses, including both SARS-CoV-like and SARS-CoV-2-like viruses. In addition, pT1679 reduced the viral load in the lung of infected Syrian hamsters and prevented the severe lung pathology typical for SARS-CoV-2 infections. The cryo-electron microscopy structure of pT1679 in complex with SARS-CoV-2 S revealed that the antibody employs a YYDRxxG motif to recognize a highly conserved epitope on the RBD. Through detailed structural analysis, mutagenesis studies, and binding assays, we identified RBD residue 384 as a critical determinant of antibody recognition. Structure-function analyses of several related bnAbs, such as COVA1-16, allowed for the classification of YYDRxxG antibodies into two distinct groups that differ in neutralization breadth. Our findings provide crucial insights into the molecular basis of broad Sarbecovirus neutralization and offer strategic guidance for selecting therapeutic antibodies in preparation for future Sarbecovirus outbreaks
Multiphysics Analysis of Cryogenically Cooled Photocathode in a CW SRF Injector cavity
No full textThe paper evaluates the thermal regime of a cryogenically cooled copper photocathode integrated into a continuous-wave superconducting radio-frequency injector cavity with direct thermal contact. Such a photoinjector layout is being developed at DESY and has recently demonstrated a record high 50 MV/m axial electric field in radio-frequency tests, marking an important milestone. To address the thermal effect of the picosecond excitation laser, we first develop a two-temperature model to describe the temperature of the emitting surface at cryogenic temperatures and solve it numerically. Subsequently, we present a one-temperature model of the bulk photocathode coupled with an electromagnetic model of the injector cavity. For the current injector design, we predict a negligible impact of the laser on the intrinsic quality factor of the cavity, identifying instead the cryogenic stability of the copper cathode as the primary operational limit. To overcome cooling challenges, we propose an improved configuration of the cathode plug. For the proposed geometry, the multiphysics analysis confirms stable performance at a nominal 2 W laser power, sufficient for 100 pC beams at 1 MHz under optimistic quantum efficiency assumptions. Operation at higher laser loads will benefit from further dedicated cryogenic analysis
From Science to Fiction – Connecting In Vivo and In Vitro Results in Polyprotein Processing of Coronaviruses
No full textPolyprotein processing is a common strategy in many positive sense single-stranded RNA ((+)ssRNA) viruses. This highly regulated process is crucial for viral progeny and ensures the release of functional replicase proteins in the correct location and at the right time. Coronaviruses (CoVs) have one of the largest genomes on average among (+)ssRNA viruses requiring a unique replication-transcription complex (RTC) with proofreading function that prevents error catastrophe. Two thirds of the CoV genome encode for the non-structural proteins (nsps) that drive replication. These are directly synthesized by RNA genome translation after infection as two large polyproteins pp1a and pp1ab. A regulated polyprotein proteolytic auto-processing is essential for viral growth and always has been an interesting target for therapeutics.Here, we present an overview of polyprotein processing and RTC research in CoVs in vitro and in vivo over the last 30 years. We highlight cutting-edge methodologies such as super resolution microscopy or structural mass spectrometry approaches and demonstrate how these have contributed to polyprotein research, e.g. by providing comprehensive structural models. We illustrate exciting examples of polyprotein processing in other viruses that could be transferred to CoVs, too. Additionally, we identify critical knowledge gaps in polyprotein processing and RTC assembly, proposing future perspectives to address these limitations
Accelerated Electro‐Conversion of a Nickel Coordination Complex for Hybrid Water Electrolysis
No full textElectrocatalytic energy conversion relies on the dynamic transformation of electrode materials into “electrocatalytically active phases” under reaction conditions. Pre-catalysts, which undergo extensive structural and chemical changes during electrochemical activation, are particularly promising in this regard. In the context of electrocatalysis, coordination complexes with labile ligands offer a unique advantage, as they can rapidly reconstruct under electrochemical conditions. Herein, a hydrazine-coordinated Ni complex embedded in a conductive carbon nanotube matrix is presented as a pre-catalyst for urea-assisted hybrid water electrolysis, that transforms into highly active γ-NiOOH nanosheets on electrochemical activation, demonstrating exceptional urea electrooxidation performance, with a low Tafel slope of 21.6 mV dec−1, a high turnover frequency (TOF) of 0.0728 s−1, and stable operation over 40 h of continuous electrolysis, reflecting superior catalytic kinetics and excellent durability. In situ synchrotron X-ray absorption, Raman, and electrochemical impedance spectroscopy reveal the dynamic evolution of active sites, the underlying reaction mechanism, and the fate of the active species after prolonged electrolysis. The integration of this pre-catalyst into an anion-exchange membrane electrolyzer highlights its potential for practical application. This work showcases the transformative role of Ni-based coordination complexes as pre-catalysts, offering an innovative blueprint for the rational design of high-performance urea oxidation electrocatalysts
Influence of diameter on high-pressure induced phase transitions in bismuth nanowire networks
No full textSize-dependent behavior of bismuth nanowire networks under high-pressure conditions was investigated at room temperature. Three-dimensional networks of freestanding interconnected bismuth nanowires with diameters between 34 and 85nmwere synthesized by electrodeposition in ion-track etched membranes, along with microcrystals as bulk analogues. Both types of samples were simultaneously compressed in diamond anvil cells under hydrostatic conditions up to 19.5GPa. Synchrotron x-ray diffraction data reveal a shift of the Bi-I/-II, Bi-II/-III, and Bi-III/-V phase transition to higher-pressure values for decreasing nanowire diameter. In case of the thinnest wires, compression and decompression cycles revealed hysteresislike behavior of the shifts and a pronounced coexistence of the Bi-III and Bi-V phases upon compression. All samples exhibited bulklike compression behavior, as reflected in the evolution of their lattice parameter and bulk modulus. Only nanowires in the Bi-III phase showed a slightly reduced modulus compared to the corresponding bulk value. The systematic size dependence highlights the importance of excellent control on the geometrical parameters of the nanowires and consistent experimental conditions. The mechanical stability of the three-dimensional nanowire networks allowed the pressurization of samples of varying wire diameters under identical experimental conditions and facilitates systematic studies of size effects in nanomaterials with diameters as small as 10nm
Carbon Monoxide-Induced Mobility of Isolated Palladium Species on Silicon Dioxide at Room Temperature
No full textCarbon monoxide is a well-established probe molecule and common reactant. However, it can also influence sintering, especially for highly dispersed systems. In this study, we investigated the reactivity of carbon monoxide with two well-defined, silica-supported palladium surface complexes, differing in the donor–acceptor properties of their ligands. In fact, the presence of a phosphine or amine ligand clearly determined the reactivity and final dispersion of palladium in the supported catalyst model systems. For the amine surface complex ≡SiO-PdMe(tmeda) (tmeda: N, N, N’, N’- tetramethylenediamine), reductive decomposition and agglomeration to palladium particles were observed at room temperature by in situ IR spectroscopy and X-ray absorption spectroscopy. In contrast, the fast aggregation was prevented for ≡SiO-PdMe(dppe) (dppe: 1,2-bis(diphenylphosphino)ethane). The insertion of CO into the Pd-methyl bond was identified by in situ IR spectroscopy in both cases. Density functional theory calculations addressed the differences in reactivity, discovering a lower activation barrier of the first CO insertion for the tmeda complex. The study draws a detailed mechanism of structural changes at silica-supported palladium species under carbon monoxide, which must be considered when highly dispersed palladium metal species are handled under CO, e.g., for catalyst characterization by chemisorption and preparation procedures, even at very mild conditions
Three-Dimensional Distribution of Titanium Hydrides After Degradation of Magnesium/Titanium Hybrid Implant Material—A Study by X-Ray Diffraction Contrast Tomography
No full textHybrid implants composed of magnesium and titanium are a promising direction in orthopaedics, as these implants combine the stability of titanium with the biological activity of magnesium. These partly soluble implants require careful investigation, as the degradation of magnesium releases hydrogen, which can enter the Ti matrix and thus alter the mechanical properties. To investigate this scenario and quantify the hydrogen uptake along with its structural impacts, we employed inert gas fusion, scanning electron microscopy, X-ray diffraction, and a combination of synchrotron absorption and X-ray diffraction tomography. These techniques enabled us to investigate the concentration and distribution of hydrogen and the formation of hydrides in the samples. Titanium hydride formation was observed in a region approximately 120 µm away from the titanium surface and correlates with the amount of absorbed hydrogen. We speculate that the degradation of magnesium at the magnesium/titanium implant interface leads to the penetration of hydrogen due to a combination of electrochemical and gaseous charging
Energy Transfer by Feebly Interacting Particles in Supernovae: The Trapping Regime
No full textFeebly interacting particles, such as sterile neutrinos, dark photons, and axions, can be abundantly produced in the proto-neutron star (PNS) formed in core-collapse supernovae (CCSNe). These particles can decay into photons or charged leptons, depositing energy outside the PNS. Strong bounds on new particles can thus be derived from the observed luminosity of CCSNe, with even tighter bounds obtained from low-energy SNe observations. For the first time we highlight that, at sufficiently large couplings, particle production outside the PNS must also be considered. Using the prototypical case of axions coupling to two photons, we show that at large couplings the energy transfer from PNS to its surroundings is diffusive rather than ballistic, substantially reducing the deposited energy. Our findings have implications for the parameter space of particles probed in beam dump experiments and for dark matter models involving a sub-GeV mediator
Recommendations for Best Practices for Data Preservation and Open Science in HEP
No full textThese recommendations are the result of reflections by scientists and experts who are, or have been, involved in the preservation of high-energy physics data. The work has been done under the umbrella of the Data Lifecycle panel of the International Committee of Future Accelerators (ICFA), drawing on the expertise of a wide range of stakeholders. A key indicator of success in the data preservation efforts is the long-term usability of the data. Experience shows that achieving this requires providing a rich set of information in various forms, which can only be effectively collected and preserved during the period of active data use. The recommendations are intended to be actionable by the indicated actors and specific to the particle physics domain. They cover a wide range of actions, many of which are interdependent. These dependencies are indicated within the recommendations and can be used as a road map to guide implementation efforts. These recommendations are best accessed and viewed through the web application, see https://icfa-data-best-practices.app.cern.ch