Publications by authors named "Hirai D"

Clarifying the underlying mechanisms that govern ordering transitions in condensed matter systems is crucial for comprehending emergent properties and phenomena. While transitions are often classified as electronically driven or lattice-driven, we present a departure from this conventional picture in the case of the double perovskite BaMgReO. Leveraging resonant and non-resonant elastic x-ray scattering techniques, we unveil the simultaneous ordering of structural distortions and charge quadrupoles at a critical temperature of T ~ 33 K.

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Background: Infection is a rare complication of percutaneous renal biopsy (RB). However, the questionnaire included in the Kidney Biopsy Guidebook 2020 in Japan revealed that antibiotic prophylaxis (AP) was administered at about 60% of hospitals. The objective of this study was to evaluate whether it is possible to omit AP for RB.

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Article Synopsis
  • A 64-year-old Japanese woman diagnosed with stage IVB cervical cancer experienced gross hematuria and renal dysfunction after chemoradiation therapy.
  • A renal biopsy indicated rare complications: renal thrombotic microangiopathy (TMA) and tubulointerstitial nephritis (TIN), which are unusual for radiation nephropathy.
  • The use of contrast-enhanced CT identified high radiation dose areas in the kidneys, demonstrating the need for a combined approach of clinical, pathological, and radiological assessments in diagnosing radiation nephropathy.
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Exotic quantum phases, arising from a complex interplay of charge, spin, lattice and orbital degrees of freedom, are of immense interest to a wide research community. A well-known example of such an entangled behavior is the Jahn-Teller effect, where the lifting of orbital degeneracy proceeds through lattice distortions. Here we demonstrate that a highly-symmetrical 5d double perovskite BaMgReO, comprising a 3D array of isolated ReO octahedra, represents a rare example of a dynamic Jahn-Teller system in the strong spin-orbit coupling regime.

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  • - The study compares how pulmonary oxygen uptake (VO2p), muscle deoxygenation ([HHb]), and microvascular oxygen delivery (QOmv) differ between heart failure patients with reduced ejection fraction (HFrEF) and those with preserved ejection fraction (HFpEF).
  • - HFrEF patients showed significantly slower VO2 kinetics, quicker muscle deoxygenation responses, and higher microvascular oxygen delivery compared to HFpEF patients, along with a shorter time to exercise intolerance.
  • - The analysis revealed that higher body fat negatively affects oxygen diffusion and exercise performance, while increased lean muscle correlates positively with better oxygen uptake and muscle oxygenation in HFrEF patients.
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Sickle cell disease (SCD) is characterized by central (cardiac) and peripheral vascular dysfunctions, significantly diminishing exercise capacity and quality of life. Although central cardiopulmonary abnormalities in SCD are known to reduce exercise capacity and quality of life; the impact of hemolysis and subsequent cell-free hemoglobin (Hb)-mediated peripheral vascular abnormalities on those outcomes are not fully understood. Despite the recognized benefits of exercise training for cardiovascular health and clinical management in chronic diseases like heart failure, there remains substantial debate on the advisability of regular physical activity for patients with SCD.

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The 5d^{1} ordered double perovskites present an exotic playground for studying novel multipolar physics due to large spin-orbit coupling. We present Re L_{3} edge resonant inelastic x-ray scattering (RIXS) results that reveal the presence of the dynamic Jahn-Teller effect in the A_{2}MgReO_{6} (A=Ca, Sr, Ba) family of 5d^{1} double perovskites. The spin-orbit excitations in these materials show a strongly asymmetric line shape and exhibit substantial temperature dependence, indicating that they are dressed with lattice vibrations.

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Baumgartner, NW, Belbis, MD, Kargl, C, Holmes, MJ, Gavin, TP, Hirai, DM, and Kao, S-C. Acute effects of high-intensity resistance exercise on recognition of relational memory, lactate, and serum and plasma brain-derived neurotrophic factor. J Strength Cond Res 38(11): 1867-1878, 2024-Acute aerobic exercise improves memory, but this phenomenon is understudied in response to resistance exercise (RE) despite evidence that RE-induced increases in lactate and brain-derived neurotrophic factor (BDNF) play mechanistic roles in memory performance.

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The magnetic ground state of single crystalline RuO_{2} was investigated by the muon spin rotation and relaxation (μSR) experiment. The spin precession signal due to the spontaneous internal magnetic field B_{loc}, which is expected in the magnetically ordered phase, was not observed in the temperature range 5-400 K. Muon sites were evaluated by first-principles calculations using dilute hydrogen simulating muon as pseudohydrogen, and B_{loc} was simulated for the antiferromagnetic structures with a Ru magnetic moment |m_{Ru}|≈0.

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Heteroanionic compounds, which contain two or more types of anions, have emerged as a promising class of materials with diverse properties and functionalities. In this paper, I review the experimental findings on CaReOCl and related compounds that exhibit remarkable pleochroism and novel quantum magnetism. I discuss how the heteroanionic coordination affects the optical and magnetic properties by modulating the d-orbital states of the transition metal ions.

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Being a dialysis patient is one of the risks for severe coronavirus disease 2019 (COVID-19) cases. In addition, there have been many reports of coagulation abnormalities in severe COVID-19 cases; these also make dialysis management more difficult. In this study, we report a case of severe COVID-19 in a hemodialysis patient who had coagulation in the dialysis circuit with unfractionated heparin (UFH), which could be managed without intracircuit obstruction when nafamostat mesylate (NM) was used in combination with unfractionated heparin.

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Photoelectrochemical (PEC) water splitting is a highly demanded technology for the realization of sustainable society. Various types of photoanodes have been developed to achieve high efficiency of PEC water splitting. Plasmonic field enhancement and light confinement effects are often adopted to improve PEC performance.

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Article Synopsis
  • The study examined how sildenafil, a drug that enhances nitric oxide pathways, affects oxygen levels in muscle tissue during activity.
  • High-dose sildenafil increased resting oxygen levels in muscle compared to control and low-dose groups, improving oxygen availability during muscle recovery.
  • While sildenafil reduced blood pressure, it did not affect the speed of oxygen response during muscle contractions but did enhance oxygen transport in muscle, suggesting benefits for repeated muscle activity.
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The high-entropy concept was applied to the synthesis of transition-metal antimonides, MPtSb (M = equimolar Ru, Rh, Pd, and Ir). High-entropy antimonide samples crystallized in a pseudo-hexagonal NiAs-type crystal structure with a 6/ space group were successfully synthesized through a conventional solid-state reaction and subsequent quenching. A detailed investigation of the composition and equilibration conditions confirmed the reversible phase transition between a multiphase state at low temperature and an entropy-driven single-phase solid solution at high temperatures.

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Quantum oscillations (QOs) in magnetic torque and electrical resistivity were measured to investigate the electronic structure of-ReO, a candidate hourglass nodal chain (NC) metal (Dirac loop chain metal). All the de Haas-van Alphen oscillation branches measured at 30 mK in magnetic fields of up to 17.5 T were consistent with first-principles calculations predicting four Fermi surfaces (FSs).

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The mixed-valent spinel LiVO is known as the first oxide heavy-fermion system. There is a general consensus that a subtle interplay of charge, spin, and orbital degrees of freedom of correlated electrons plays a crucial role in the enhancement of quasi-particle mass, but the specific mechanism has remained yet elusive. A charge-ordering (CO) instability of V and V ions that is geometrically frustrated by the V pyrochlore sublattice from forming a long-range CO down to = 0 K has been proposed as a prime candidate for the mechanism.

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Reductive fluorination, which entails the substitution of O from oxide compounds with F from fluoropolymers, is considered a practical approach for preparing transition-metal oxyfluorides. However, the current understanding of the fundamental reaction paths remains limited due to the analytical complexities posed by high-temperature reactions in glassware. Therefore, to expand this knowledgebase, this study investigates the reaction mechanisms behind the reductive fluorination of WO using polytetrafluoroethylene (PTFE) in an Ni reactor.

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The 5pyrochlore oxide superconductor CdReO(CRO) has attracted significant interest as a spin-orbit-coupled metal (SOCM) that spontaneously undergoes a phase transition to an odd-parity multipole phase by breaking the spatial inversion symmetry due to the Fermi liquid instability caused by strong spin-orbit coupling. Despite the significance of structural information during the transition, previous experimental results regarding lattice deformation have been elusive. We have conducted ultra-high resolution synchrotron radiation x-ray diffraction experiments on a high-quality CRO single crystal.

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The observation of spinon excitations in the [Formula: see text] triangular antiferromagnet CaReOCl reveals a quasi-one-dimensional (1D) nature of magnetic correlations, in spite of the nominally 2D magnetic structure. This phenomenon is known as frustration-induced dimensional reduction. Here, we present high-field electron spin resonance spectroscopy and magnetization studies of CaReOCl, allowing us not only to refine spin-Hamiltonian parameters, but also to investigate peculiarities of its low-energy spin dynamics.

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Charge transfer (CT) luminescence of different types of polyhedra, [WO] in CaWOCl and [WO] in CaWO, is characterized by spectroscopic experiments and calculations. According to the geometry optimization, W ions form five-fold [WO] square pyramids in CaWOCl because of a large interatomic distance between W and Cl of 3.266 Å.

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Some inorganic solids undergo phase transitions that result in the formation of "molecules" in their crystalline frameworks, which are frequently accompanied by dramatic changes in physical properties; the metal-insulator transition (MIT) in vanadium dioxide, for instance, is accompanied by the formation of dimer molecules with conventional two-center-two-electron bonding. We have discovered the creation of a linear ruthenium trimer with atypical three-center-four-electron bonding in ruthenium monophosphide at its MIT. Our detailed structural investigation and electronic structure calculations reveal that charge transfer from polymerized phosphorous to ruthenium automatically tunes the electron density to precisely four per trimer at the MIT, with all conduction electrons present at high temperatures being trapped by the trimer's molecular orbitals at low temperatures.

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Amorphous solid dispersion (ASD) is a preparation widely used for improving the solubility and low oral absorbability of poorly water-soluble drugs, but the quantitative analysis of its dissolution profiles and its supersaturation status remains an important issue. We previously reported a new mathematical model for analyzing the dissolution characteristics of ASD preparations that enabled evaluation of theoretical solubility of ASDs and crystal precipitation rate constants of ASD preparations. In this study, to analyze the relationship between the mathematical parameters of the model and the dissolution behavior in detail, we simulated the dissolution behaviors upon changing parameters.

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Objective: To investigate whether newer anti-seizure medications (ASMs) are widely prescribed for a range of adult patients in Japan, including patients with previously and newly diagnosed epilepsy, or with focal and generalized epilepsies.

Methods: A retrospective cohort study was conducted using the Japanese insurance claims database including 8.4 million people to identify adults (≥16 years of age) with epilepsy diagnosis code identified between January 2015 and December 2018.

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A 57-year-old Japanese man on peritoneal dialysis developed peritoneal dialysis-associated peritonitis caused by Rhodococcus corynebacterioides. After the introduction of peritoneal dialysis, he had experienced four episodes of peritonitis, but the causative organism was not identified in any of episode. When he was hospitalized for the fifth episode of peritonitis, Rhodococcus corynebacterioides was detected in the ascitic fluid.

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