Abstract
Using a combination of photostimulated desorption and resonance-enhanced multiphoton ionization methods, the behaviors of OH radicals on the surface of an interstellar ice analog were ...monitored at temperatures between 54 and 80 K. The OH number density on the surface of ultraviolet-irradiated compact amorphous solid water gradually decreased at temperatures above 60 K. Analyzing the temperature dependence of OH intensities with the Arrhenius equation, the decrease can be explained by the recombination of two OH radicals, which is rate-limited by thermal diffusion of OH. The activation energy for surface diffusion was experimentally determined for the first time to be 0.14 ± 0.01 eV, which is larger than or equivalent to those assumed in theoretical models. This value implies that the diffusive reaction of OH radicals starts to be activated at approximately 36 K on interstellar ice.
We have performed experimental investigations of methanol formation via the reactions of low-energy CH3+ ions with an amorphous solid water (ASW) surface at ∼10 K. A newly developed experimental ...apparatus enabled irradiation of the ASW surface by several eV ions and detection of trace amounts of reaction products on the surface. It was found that methanol molecules were produced by low-energy CH3+ irradiation of the ASW surface and that hydroxy groups in the produced methanol originated from water molecules in the ASW, as predicted in a previous theoretical study. Little temperature dependence of the observed methanol intensity is apparent in the temperature range 12–60 K. Ab initio molecular dynamics simulations under constant-temperature conditions of 10 K suggested that this reaction spontaneously produced a methanol molecule and an H3O+ ion, regardless of the contact point of CH3+ on the ASW surface. We have performed a simulation with an astrochemical model under molecular-cloud conditions, where the reaction between CH3+ and H2O ice, leading to methanol formation, was included. We found that the impact of the reaction on methanol abundance was limited only at the edge of the molecular cloud (<1 mag) because of the low abundance of CH3+ in the gas phase, whereas the reaction between the abundant molecular ion (HCO+) and H2O ice, which has not yet been confirmed experimentally, can considerably affect the abundance of a complex organic molecule. This work sheds light on a new type of reaction between molecular ions and ice surfaces that should be included in astrochemical models.
Spin dynamics evolution of BaFe2(As(1-x)Px){2} was probed as a function of P concentration via 31P NMR. Our NMR study reveals that two-dimensional antiferromagnetic (AF) fluctuations are notably ...enhanced with little change in static susceptibility on approaching the AF phase from the superconducting dome. Moreover, the magnetically ordered temperature θ deduced from the relaxation rate vanishes at optimal doping. These results provide clear-cut evidence for a quantum-critical point, suggesting that the AF fluctuations associated with the quantum-critical point play a central role in the high-T(c) superconductivity.
Cosmogenic nuclides in tree rings and polar ice cores record the information of past cosmic ray intensities and solar activities. A large 14C increase over 10 years has been discovered around 5480 ...BCE. The 14C variations in this event differ from those of other short‐term cosmic ray events and typical grand solar minima. To elucidate the cause of the 14C increase around 5480 BCE, we measured the 10Be and 36Cl concentrations in the Antarctic Dome Fuji ice core at quasi‐annual and 4–5 years resolutions, respectively. Based on the combined 14C, 10Be, and 36Cl data, the 5480 BCE event was probably not caused by a solar proton event (SPE) or a gamma‐ray event, because the 36Cl concentration did not significantly increase as expected in these events. The incremented 10Be data were enhanced similarly to those of recent grand solar minima, but more rapidly increased (over ∼10 years). These results suggest that an unusual grand solar minimum occurred around 5480 BCE, characterized by a rapidly decreasing solar activity.
Key Points
New high‐resolution 10Be and 36Cl data for the 5480 BCE cosmic ray event were taken from the Antarctic Dome Fuji ice core
Measured 36Cl/10Be ratio was not suitable for either solar proton event or gamma‐ray event origins
The 5480 BCE event might refer to the unusual grand solar minimum which solar activity decreased rapidly in ∼10 years
We propose a data-driven technique to infer microscopic physical quantities from nuclear magnetic resonance (NMR) spectra, in which the data size and quality required for the Bayesian inference are ...investigated. The 59Co-NMR measurement of YbCo2Zn20 single crystal generates complex spectra with 28 peaks. By exploiting the site symmetry in the crystal structure, the isotropic Knight shift Kiso and nuclear quadrupole resonance (NQR) frequency νQ were respectively estimated to be Kiso=0.7822±0.0090% and νQ=2.008±0.016 MHz (T=20 K and H≃10.2 T) by analyzing only 30 data points from one spectrum. The estimated νQ is consistent with the precise value obtained in the NQR experiment. Our method can significantly reduce the measurement time and the computational cost of data analysis in NMR experiments.
The mandibular condylar cartilage (MCC) is an essential component of the temporomandibular joint, which orchestrates the vertical growth of the mandibular ramus through endochondral ossification with ...distinctive modes of cell differentiation. Parathyroid hormone–related protein (PTHrP) is a master regulator of chondrogenesis; in the long bone epiphyseal growth plate, PTHrP expressed by resting zone chondrocytes promotes chondrocyte proliferation in the adjacent layer. However, how PTHrP regulates chondrogenesis in the MCC remains largely unclear. In this study, we used a Pthrp-mCherry knock-in reporter strain to map the localization of PTHrP+ cells in the MCC and define the function of PTHrP in the growing mandibular condyle. In the postnatal MCC of Pthrp
mCherry/+
mice, PTHrP-mCherry was specifically expressed by cells in the superficial layer immediately adjacent to RUNX2-expressing cells in the polymorphic layer. PTHrP ligands diffused across the polymorphic and chondrocyte layers where its cognate receptor PTH1R was abundantly expressed. We further analyzed the mandibular condyle of Pthrp
mCherry/mCherry
mice lacking functional PTHrP protein (PTHrP-KO). At embryonic day (E) 18.5, the condylar process and MCC were significantly truncated in the PTHrP-KO mandible, which was associated with a significant reduction in cell proliferation across the polymorphic layer and a loss of SOX9+ cells in the chondrocyte layers. The PTHrP-KO MCC showed a transient increase in the number of Col10a1+ hypertrophic chondrocytes at E15.5, followed by a significant loss of these cells at E18.5, indicating that superficial layer–derived PTHrP prevents premature chondrocyte exhaustion in the MCC. The expression of Runx2, but not Sp7, was significantly reduced in the polymorphic layer of the PTHrP-KO MCC. Therefore, PTHrP released from cells in the superficial layer directly acts on cells in the polymorphic layer to promote proliferation of chondrocyte precursor cells and prevent their premature differentiation by maintaining Runx2 expression, revealing a unique PTHrP gradient-directed mechanism that regulates MCC chondrogenesis.
Abstract Yokukansan (YKS), a traditional Japanese medicine, is composed of seven kinds of dried herbs. It is widely prescribed in clinical situation for treating psychiatric disorders such as ...aggressiveness in patients with dementia. We previously demonstrated that YKS and Uncaria hook (UH), which is a constituent herb of YKS, had a partial agonistic effect to 5-HT1A receptors in vitro . However, it has still been unclear whether this in vitro effect is reflected in in vivo , and what the active ingredients are. The purpose of the present study is to find the active ingredient in YKS and to demonstrate the effect in in vivo . In the present study, we first studied the effect of YKS and UH on aggressiveness and sociality in socially isolated mice. YKS and UH ameliorated the isolation-induced increased aggressiveness and decreased sociality, and these ameliorative effects were counteracted by coadministration of 5-HT1A receptor antagonist WAY-100635, or disappeared by eliminating UH from YKS. These results suggest that the effect of YKS is mainly attributed to UH, and the active ingredient is contained in UH. To find the candidate ingredients, we examined competitive binding assay and 35 S guanosine 5′-O-(3-thiotriphosphate) (GTPγS) binding assay of seven major alkaloids in UH using Chinese hamster ovary cells expressing 5-HT1A receptors artificially. Only geissoschizine methyl ether (GM) among seven alkaloids potently bound to 5-HT1A receptors and acted as a partial agonist. This in vitro result on GM was further demonstrated in the socially isolated mice. As did YKS and UH, GM ameliorated the isolation-induced increased aggressiveness and decreased sociality, and the effect was counteracted by coadministration of WAY-100635. These lines of results suggest that GM in UH is potent 5-HT1A receptor agonist and a candidate for pharmacological effect of YKS on aggressiveness and sociality in socially isolated mice.
A new coating and forming process is reported for perovskite solar cells and modules. Power conversion efficiencies (PCEs) of 15.0% in the active area and 14.0% in the aperture area are achieved in a ...module consisting of four sub-cells connected in series with an aperture area of 5 cm × 5 cm. The I–V characteristics of the cells and modules show low hysteresis. This new process consists of three steps: coating, gas blowing, and dipping into an antisolvent. The process exhibits high reproducibility of PCE in 1 cm2 cells, and forms the perovskite layer over a large area. The size effect of the active area on the PCE is little in the cell (active area: 0.5 cm2) and module (active area: 25 cm2). This approach paves the way for the industrial production of large-scale perovskite modules.
•A perovskite fabrication process consists of coating, gas blowing and dipping.•The standard deviation of the power conversion efficiency (PCE) was ±0.12%.•Module's PCE was 15.0% in the active area and 14.0% in the aperture area.•The module showed low hysteresis in the J-V curves.
From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T(Curie)∼2.5 K and T(SC)∼0.6 K), we show that superconductivity in UCoGe is tightly coupled ...with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (H∥c) strongly suppress the FM fluctuations and that the superconductivity is observed in the limited magnetic-field region where the longitudinal FM spin fluctuations are active. These results, combined with model calculations, strongly suggest that the longitudinal FM spin fluctuations tuned by H∥c induce the unique spin-triplet superconductivity in UCoGe. This is the first clear example that FM fluctuations are intimately related with superconductivity.
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