Stress-Induced Martensitic Transformation in Na3YCl6.

Martensitic transformation with volume expansion plays a crucial role in enhancing the mechanical properties of steel and partially stabilized zirconia. We believe that a similar concept could be applied to unexplored nonoxide materials. Herein, we report the stress-induced martensitic transformation of monoclinic Na3YCl6 with an ∼3.4% expansion. In situ synchrotron X-ray diffraction and atomistic simulations showed that anisotropic crystallographic transformation from monoclinic to rhombohedral Na3YCl6 occurs exclusively under uniaxial pressure; no effect is observed under hydrostatic pressure conditions. The uniaxially pressed powder compact of monoclinic Na3YCl6 showed a large indentation impression and low Young's modulus, in contrast to its high bulk modulus, suggesting that these unique mechanical properties are induced by the martensitic transformation.

Intrinsic Magnetic Proximity Effect at the Atomically Sharp Interface of CoxFe3-xO4/Pt Grown by Molecular Beam Epitaxy.

CoxFe3-xO4(CFO)/Pt bilayers prepared by molecular beam epitaxy were investigated for the anomalous Hall effect and X-ray magnetic circular dichroism (XMCD). We found that the anomalous Hall effect originates from a magnetic proximity effect at the CFO/Pt interface. The XMCD signal in the Pt L-edge was obtained only for the sample deposited at 600 °C, indicating that the magnetic proximity effect is sensitive to the interface structure. Transmission electron microscopy images of the CFO/Pt interface and XMCD measurements of Co and Fe L-edges do not provide direct evidence for interfacial atomic diffusion or alloying. In summary, these results suggest that the magnetic proximity effect is robust for transport properties, such as the anomalous Hall effect, while the induced magnetic moment depends on slight differences in the interfacial structure, such as the presence or absence of interfacial oxygen ions.

Ultrahigh pressure-induced modification of morphology and performance of MOF-derived Cu@C electrocatalysts.

We report the pyrolysis of copper-containing metal-organic frameworks under high pressure and the effect of the applied pressure on the morphology and electrocatalytic performance toward the oxygen-related reactions of the products. The high-pressure and high-temperature (HPHT) syntheses were performed under 5, 2.5, 1, and 0.5 GPa, and the Cu@C products were obtained except for the 2.5 GPa experiment. Copper formed a shell-like nanostructure on the carbon matrices during the 0.5 GPa experiment, whereas copper formed sub-nanometer sized particles in the carbon matrices with the increasing pressure. It is considered that the transportation of copper atoms by outgassing during the pyrolysis affects the morphology. Electrochemical measurements revealed that all samples exhibited activity for the oxygen reduction reaction (ORR). The 0.5 GPa-treated product also exhibited the oxygen evolution reaction (OER). The overall ORR/OER performance of this product was excellent among Cu-based bifunctional materials even though it did not contain cocatalysts such as nitrogen-doped carbon or other metal elements. The Cu(iii) species in the nano-thick copper shell structure provided the active sites for the OER.

Synthesis of Epitaxial MoS2/MoO2 Core-Shell Nanowires by Two-Step Chemical Vapor Deposition with Turbulent Flow and Their Physical Properties.

MoO2 nanowires (NWs), MoO2/MoS2 core-shell NWs, and MoS2 nanotubes (NTs) were synthesized by the turbulent flow chemical vapor deposition of MoO2 using MoO3, followed by sulfurization in the sulfur gas flow. The involvement of MoO x suboxide is suggested by density functional theory (DFT) calculations of the surface energies of MoO2. The thickness of the MoS2 layers can be controlled by precise tuning of sulfur vapor flow and temperatures. MoS2 had an armchair-type winding topology due to the epitaxial relation with the MoO2 NW surface. A single ∼ few-layer MoO2/MoS2 core-shell structure showed photoluminescence after the treatment with a superacid. The resistivities of an individual MoO2 NW and a MoS2 NT were measured, and they showed metallic and semiconducting resistivity-temperature relationships, respectively.

Hygienic behaviors during the COVID-19 pandemic may decrease immunoglobulin G levels: Implications for Kawasaki disease.

BACKGROUND: Due to the coronavirus disease 2019 (COVID-19) pandemic, hygienic behaviors became a new norm since January 2020. The hygiene hypothesis predicts that an excessively hygienic environment may adversely affect human health. OBJECTIVE: We quantified the effect of COVID-19 on immunological parameters linked to the hygiene hypothesis. METHODS: We examined age-specific levels of total nonspecific immunoglobulin G (IgG) and IgE in individuals who visited Fukuoka Tokushukai Hospital between 2010 and 2021. Pre-COVID (2010-2019) and COVID (2020-2021) periods were compared. RESULTS: IgG levels steadily decreased throughout Pre-COVID period. IgG levels fell abruptly from the pre-COVID period to the COVID period in all age groups (P = 0.0271, < 0.3 years; P = 0.0096, 0.3-5 years; P = 0.0074, ≥ 5 years). The declines in IgG in < 0.3 years and that in ≥ 5 years accelerated during the COVID period. IgE levels were seasonal, but did not change noticeably from the pre-COVID to COVID period. IgG levels recorded for patients with Kawasaki disease (KD) (mean 709 mg/dL) were significantly lower than for matched control subjects (826 mg/dL) (P<0.0001). DISCUSSION: Hygienic behaviors during the COVID-19 outbreak decreased the chance of infection, which may explain the decreases in IgG levels in children and adults. Neonatal IgG declined, possibly because of the decrease in maternal IgG. CONCLUSION: Hygienic behaviors decreased the IgG levels in all age groups, from neonates to adults. This downturn in IgG may lead to vulnerability to infections as well as to KD.

Ultrahigh-Pressure Preparation and Catalytic Activity of MOF-Derived Cu Nanoparticles.

A metal-organic framework (MOF) consisting of Cu-benzenetricarboxylic acid was processed under ultrahigh pressure (5 GPa) and at temperature of up to 500 °C. The products were characterized with TEM, FTIR, and XAFS. The decomposition of the MOF started at 200 °C at 5 GPa. This temperature was much lower than that in the vacuum. Single-nanometer Cu nanoparticles were obtained in carbon matrix, which was significantly smaller than the Cu particles prepared at ambient pressure. The catalytic activity for Huisgen cycloaddition was examined, and the sample processed at 5 GPa showed a much improved performance compared with that of the MOF-derived Cu nanoparticles prepared without high pressure.

Synthesis of Boron Nitride Nanotubes Using Plasma-Assisted CVD Catalyzed by Cu Nanoparticles and Oxygen.

We found that oxidized Cu nanoparticles can catalyze the growth of boron nitride nanotubes from borazine via plasma-assisted chemical vapor deposition. The Raman spectra suggest that the formation of thin-walled nanotubes show a radial breathing mode vibration. The presence of oxygen in the plasma environment was necessary for the growth of the nanotubes, and a part of the nanotubes had a core shell structure with a cupper species inside it. In atomic resolution transmission electron microscope (TEM) images, Cu2O was found at the interface between the Cu-core and turbostratic BN-shell. The growth mechanism seemed different from that of carbon nanotube core-shell structures. Therefore, we pointed out the important role of the dynamic morphological change in the Cu2O-Cu system.

Formation of a calcium oxalate urethral stone in a 3-year-old boy due to hypocitraturia.

INTRODUCTION: Urolithiasis in children is often due to metabolic abnormalities (e.g. hypocitraturia) and hence recurs frequently. CASE PRESENTATION: A 3-year-old boy presented with gross hematuria. Computed tomography detected a urethral calculus. The calculus was removed surgically. The stone was composed of calcium oxalate. Although oxalate and uric acid levels in the urine were within normal ranges, urine calcium was moderately elevated and urine citrate was substantially low. Urinalyses of the parents revealed that the father had acidic hypocitraturic urine, containing oxalate crystals, and the mother had hypercalciuria. Administration of oral citrate acid normalized urine citrate levels and eliminated the oxalate crystals, from the boy and his father. CONCLUSION: Although preventing urolithiasis using oral citrate is common in the adult population, this preventive measure is not well recognized in children, thus warranting further study.

An intubated 7-month-old infant with a retropharyngeal abscess and multidrug-resistant Streptococcus mitis.

The profile of antimicrobial resistance (ie, antibiogram) may be disparate between children and adults. An infant developed severe deep neck infection with a multidrug-resistant microbe. The microbe was more drug-resistant in children than in adults, in our hospital. Treatment of a child should be guided by the antibiogram obtained from children.