Composition templating for heterogeneous nucleation of intermetallic compounds.

Refinement of intermetallic compounds (IMCs) through enhancing heterogeneous nucleation during casting process is an important approach to improve the properties of aluminium alloys, which greatly increases the economy value of recycled Al-alloys. However, heterogeneous nucleation of IMCs is inherently more difficult than that of a pure metal or a solid solution. It requires not only creation of a crystal structure but also the positioning of 2 or more different types of atoms in the lattice with specific composition close to that of the nucleated IMCs. Previous understanding on heterogeneous nucleation is based on structural templating, usually considering the small lattice misfit at the interface between the nucleating solid and substrate. In this work, we proposed a hypothesis and demonstrated that composition templating plays a critical role in heterogeneous nucleation of IMCs. The experimental results revealed that segregation of Fe atoms on the AlB2 surface, i.e., the Fe modified AlB2 particle, provides the required composition templating and hence enhances heterogeneous nucleation of α-Al15(Fe, Mn)3Si2, resulting in a significant refinement of the α-Al15(Fe, Mn)3Si2 particles in an Al-5 Mg-2Si-1.0Mn-1.2Fe alloy.

Evaluation of QSAR models for predicting mutagenicity: outcome of the Second Ames/QSAR international challenge project.

Quantitative structure-activity relationship (QSAR) models are powerful in silico tools for predicting the mutagenicity of unstable compounds, impurities and metabolites that are difficult to examine using the Ames test. Ideally, Ames/QSAR models for regulatory use should demonstrate high sensitivity, low false-negative rate and wide coverage of chemical space. To promote superior model development, the Division of Genetics and Mutagenesis, National Institute of Health Sciences, Japan (DGM/NIHS), conducted the Second Ames/QSAR International Challenge Project (2020-2022) as a successor to the First Project (2014-2017), with 21 teams from 11 countries participating. The DGM/NIHS provided a curated training dataset of approximately 12,000 chemicals and a trial dataset of approximately 1,600 chemicals, and each participating team predicted the Ames mutagenicity of each trial chemical using various Ames/QSAR models. The DGM/NIHS then provided the Ames test results for trial chemicals to assist in model improvement. Although overall model performance on the Second Project was not superior to that on the First, models from the eight teams participating in both projects achieved higher sensitivity than models from teams participating in only the Second Project. Thus, these evaluations have facilitated the development of QSAR models.

Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-Ray Spectroscopy of Muonic Neon.

To test bound-state quantum electrodynamics (BSQED) in the strong-field regime, we have performed high precision x-ray spectroscopy of the 5g-4f and 5f- 4d transitions (BSQED contribution of 2.4 and 5.2 eV, respectively) of muonic neon atoms in the low-pressure gas phase without bound electrons. Muonic atoms have been recently proposed as an alternative to few-electron high-Z ions for BSQED tests by focusing on circular Rydberg states where nuclear contributions are negligibly small. We determined the 5g_{9/2}- 4f_{7/2} transition energy to be 6297.08±0.04(stat)±0.13(syst) eV using superconducting transition-edge sensor microcalorimeters (5.2-5.5 eV FWHM resolution), which agrees well with the most advanced BSQED theoretical prediction of 6297.26 eV.

Discovery of New Isotope

The new isotope ^{241}U was synthesized and systematic atomic mass measurements of nineteen neutron-rich Pa-Pu isotopes were performed in the multinucleon transfer reactions of the ^{238}U+^{198}Pt system at the KISS facility. The present experimental results demonstrate the crucial role of the multinucleon transfer reactions for accessing unexplored neutron-rich actinide isotopes toward the N=152 shell gap in this region of nuclides.

ADC Level is Related to DWI Reversal in Patients Undergoing Mechanical Thrombectomy: A Retrospective Cohort Study.

BACKGROUND AND PURPOSE: In patients with ischemic stroke, DWI lesions can occasionally be reversed by reperfusion therapy. This study aimed to ascertain the relationship between ADC levels and DWI reversal in patients with acute ischemic stroke who underwent recanalization treatment. MATERIALS AND METHODS: We conducted a retrospective cohort study in patients with acute ischemic stroke who underwent endovascular mechanical thrombectomy with successful recanalization between April 2017 and March 2021. DWI reversal was assessed through follow-up MR imaging approximately 24 hours after treatment. RESULTS: In total, 118 patients were included. DWI reversal was confirmed in 42 patients. The ADC level in patients with reversal was significantly higher than that in patients without reversal. Eighty-three percent of patients with DWI reversal areas had mean ADC levels of ≥520 × 10-6 mm2/s, and 71% of patients without DWI reversal areas had mean ADC levels of <520 × 10-6 mm2/s. The mean ADC threshold was 520 × 10-6 mm2/s with a sensitivity and specificity of 71% and 83%, respectively. In multivariate analysis, the mean ADC level (OR, 1.023; 95% CI, 1.013-1.033; P < .0001) was independently associated with DWI reversal. Patients with DWI reversal areas had earlier neurologic improvement (NIHSS at 7 days) than patients without reversal areas (P < .0001). CONCLUSIONS: In acute ischemic stroke, the ADC value is independently associated with DWI reversal. Lesions with a mean ADC of ≥520 × 10-6 mm2/s are salvageable by mechanical thrombectomy, and DWI reversal areas regain neurologic function. The ADC value is easily assessed and is a useful tool to predict viable lesions.

Measurements of Strong-Interaction Effects in Kaonic-Helium Isotopes at Sub-eV Precision with X-Ray Microcalorimeters.

We have measured the 3d→2p transition x rays of kaonic ^{3}He and ^{4}He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be 6224.5±0.4(stat)±0.2(syst) eV and 6463.7±0.3(stat)±0.1(syst) eV, and widths to be 2.5±1.0(stat)±0.4(syst) eV and 1.0±0.6(stat)±0.3(stat) eV, for kaonic ^{3}He and ^{4}He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential models.

Reduced Leukoaraiosis, Noncardiac Embolic Stroke Etiology, and Shorter Thrombus Length Indicate Good Leptomeningeal Collateral Flow in Embolic Large-Vessel Occlusion.

BACKGROUND AND PURPOSE: Acute leptomeningeal collateral flow is vital for maintaining perfusion to penumbral tissue in acute ischemic stroke caused by large-vessel occlusion. In this study, we aimed to investigate the clinically available indicators of leptomeningeal collateral variability in embolic large-vessel occlusion. MATERIALS AND METHODS: Among prospectively registered consecutive patients with acute embolic anterior circulation large-vessel occlusion treated with thrombectomy, we analyzed 108 patients admitted from January 2015 to December 2019 who underwent evaluation of leptomeningeal collateral status on pretreatment CTA. Clinical characteristics, extent of leukoaraiosis on MR imaging, embolic stroke subtype, time of imaging, occlusive thrombus characteristics, presenting stroke severity, and clinical outcome were collected. The clinical indicators of good collateral status (>50% collateral filling of the occluded territory) were analyzed using multivariate logistic regression analysis. RESULTS: Good collateral status was present in 67 patients (62%) and associated with independent functional outcomes at 3 months. Reduced leukoaraiosis (total Fazekas score, 0-2) was positively related to good collateral status (OR, 9.57; 95% CI, 2.49-47.75), while the cardioembolic stroke mechanism was inversely related to good collateral status (OR, 0.17; 95% CI, 0.02-0.87). In 82 patients with cardioembolic stroke, shorter thrombus length (OR, 0.91 per millimeter increase; 95% CI, 0.82-0.99) and reduced leukoaraiosis (OR, 5.79; 95% CI, 1.40-29.61) were independently related to good collateral status. CONCLUSIONS: Among patients with embolic large-vessel occlusion, reduced leukoaraiosis, noncardiac embolism mechanisms including embolisms of arterial or undetermined origin, and shorter thrombus length in cardioembolism are indicators of good collateral flow.

Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X Rays.

We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kß x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.

Scabies itch: an update on neuroimmune interactions and novel targets.

Frequently described as 'the worst itch' one can ever experience scabies itch is the hallmark of Sarcoptes scabiei mite infestation. Notably, the itchiness often persists for weeks despite scabicides therapy. The mechanism of scabies itch is not yet fully understood, and effective treatment modalities are still missing which can severely affect the quality of life. The aim of this review is to provide an overview of the scope of itch in scabies and highlight candidate mechanisms underlying this itch. We herein discuss scabies itch, with a focus on the nature, candidate underlying mechanisms and treatment options. We also synthesize this information with current understanding of the mechanisms contributing to non-histaminergic itch in other conditions. Itch is a major problem in scabies and can lead to grave consequences. We provide the latest insights on host-mite interaction, secondary microbial infection and neural sensitization with special emphasis on keratinocytes and mast cells to better understand the mechanism of itch in scabies. Also, the most relevant current modalities remaining under investigation that possess promising perspectives for scabies itch (i.e. protease-activated receptor-2 (PAR-2) inhibitor, Mas-related G protein-coupled receptor X2 (MRGPRX2) antagonist) are discussed. Greater understanding of these diverse mechanisms may provide a rational basis for the development of improved and targeted approaches to control itch in individuals with scabies.

Observation of Coulomb-Assisted Nuclear Bound State of Ξ

In an emulsion-counter hybrid experiment performed at J-PARC, a Ξ^{-} absorption event was observed which decayed into twin single-Λ hypernuclei. Kinematic calculations enabled a unique identification of the reaction process as Ξ^{-}+^{14}N→_{Λ}^{10}Be+_{Λ}^{5}He. For the binding energy of the Ξ^{-} hyperon in the Ξ^{-}-^{14}N system a value of 1.27±0.21 MeV was deduced. The energy level of Ξ^{-} is likely a nuclear 1p state which indicates a weak ΞN-ΛΛ coupling.

Properties of

Mass-separated ^{187}Ta_{114} in a high-spin isomeric state has been produced for the first time by multinucleon transfer reactions, employing an argon gas-stopping cell and laser ionization. Internal γ rays revealed a T_{1/2}=7.3±0.9 s isomer at 1778±1 keV, which decays through a rotational band with perturbations associated with the approach to a prolate-oblate shape transition. Model calculations show less influence from triaxiality compared to heavier elements in the same mass region. The isomer-decay reduced E2 hindrance factor f_{ν}=27±1 supports the interpretation that axial symmetry is approximately conserved.

Search for η

We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}N→ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ_{lab}^{ηp}<-0.9 was obtained to be 2.2 nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η^{'} production rate. Our results indicate a small branching fraction of the η^{'}N→ηN process and/or a shallow η^{'}-nucleus potential.

High-stability, high-voltage power supplies for use with multi-reflection time-of-flight mass spectrographs.

Achieving the highest possible mass resolving power in a multireflection time-of-flight mass spectrometer requires very high-stability power supplies. To this end, we have developed a programmable high-voltage power supply that can achieve long-term stability in the order of parts-per-million. Herein, we present the design of a stable high-voltage system and bench-top stability measurements up to 1 kV; a stabilization technique can, in principle, be applied up to 15 kV or more. We demonstrate that in the ≤1 Hz band, the output stability is at the level of 1 part per million (ppm) for 1 h, with only slightly more output variation across 3 days. We further demonstrate that the output is largely free of noise in the 1 Hz-200 Hz band. We also demonstrate settling to the ppm level within 1 min following a 100 V step transition. Finally, we demonstrate that when these power supplies are used to bias the electrodes of a multireflection time-of-flight mass spectrograph, the measured time-of-flight is stable at the ppm-level for at least 1 h.