42 research outputs found

    A New Cation-Ordered Structure Type with Multiple Thermal Redistributions in Co<sub>2</sub>InSbO<sub>6</sub>

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    Cation ordering in solids is important for controlling physical properties and leads to ilmenite (FeTiO(3)) and LiNbO(3) type derivatives of the corundum structure, with ferroelectricity resulting from breaking of inversion symmetry in the latter. However, a hypothetical third ABO(3) derivative with R32 symmetry has never been observed. Here we show that Co(2)InSbO(6) recovered from high pressure has a new, ordered‐R32 A(2)BCO(6) variant of the corundum structure. Co(2)InSbO(6) is also remarkable for showing two cation redistributions, to (Co(0.5)In(0.5))(2)CoSbO(6) and then Co(2)InSbO(6) variants of the ordered‐LiNbO(3) A(2)BCO(6) structure on heating. The cation distributions change magnetic properties as the final ordered‐LiNbO(3) product has a sharp ferrimagnetic transition unlike the initial ordered‐R32 phase. Future syntheses of metastable corundum derivatives at pressure are likely to reveal other cation‐redistribution pathways, and may enable ABO(3) materials with the R32 structure to be discovered

    「前提・焦点」構造からみた「は」と「が」の機能

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    和光大学The University of Wako名詞述語文を考察対象とし,「前提・焦点」構造という観点から,「は」と「が」の機能を考察する。「が」名詞述語文は,従来,「が」の前に焦点句があるタイプのみが取りあげられることが多かったが,「が」の後に焦点句があるタイプ,「が」の用いられた文全体が焦点句であるタイプも存在することを主張し,それらに共通する「が」固有の機能は,主題表示機能・焦点表示機能ではなく,格表示機能のみであることを述べる。「は」は主題表示機能を持つため,「は」文は〈主題,前提の解釈をその文のみで行うことが可能である〉文として,「が」は主題表示機能を持たず,「が」文は〈主題,前提の解釈を先行文脈や状況に依存して行う〉文として理解される。The function of the particle Wa and Ga in Japanese are normally explained using concepts such as "old information/new information" and "known/unknown". In this paper, I will explain their functions using the concept of "presupposition/focus". In a noun-predicate sentence with Ga, the function of the particle Ga has usually been explained as that of an "exhaustive listing" or "focus marker". However, the analysis of actual language data show many examples of "presupposition/focus" structures in Ga noun-predicate sentences. These are: Type 1: The focus is on the element in front of Ga. Type 2: The focus is on the element behind Ga. Type 3: The focus is on the whole sentence. I assert that it is not appropriate to explain that Ga as a focus marker because various types of Ga noun-predicate sentences exist. Furthermore, Wa marks a topic, whereas Ga does not. Therefore, Wa sentences have the following meaning: 〈The topic and presupposition of the sentence can be understood from the sentence alone without relying on the preceding context or the situation.〉 On the other hand, Ga sentences convey the following message: 〈Interpret the topic and presupposition of the sentence by relying on the preceding context and the situation.〉 The focus does not fall only on the element in front of the particle Ga. It may be on the element in front of the particle O or Ni. It may also fall on an adverbial element. Furthermore, it might exist as part of a predicate or a whole sentence. In Japanese, Ga is not the only particle that functions specifically as a focus marker

    Orthogonal antiferromagnetism to canted ferromagnetism in CaCo₃Ti₄O₁₂ quadruple perovskite driven by underlying kagome lattices

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    AA′₃B₄O₁₂ quadruple perovskites, with magnetic A′ and non-magnetic B cations, are characterized by a wide range of complex magnetic structures. These are due to a variety of competing spin-exchange interactions up to the fourth nearest neighbours. Here, we synthesize and characterize the magnetic behaviour of the CaCo₃Ti₄O₁₂ quadruple perovskite. We find that in the absence of an external magnetic field, the system undergoes antiferromagnetic ordering at 9.3 K. This magnetic structure consists of three interpenetrating mutually orthogonal magnetic sublattices. Under an applied magnetic field, this antiferromagnetic structure evolves into a canted ferromagnetic structure. In explaining these magnetic structures, as well as the seemingly unrelated magnetic structures found in other quadruple perovskites, we suggest a crucial role played by the underlying kagome lattices in these systems. All observed magnetic structures of these materials represent indeed one of the three possible ways to reduce spin frustration in the A′ site kagome layers. More specifically, our survey of the magnetic structures observed for quadruple perovskites AA′₃B₄O₁₂ reveals the following three ways to reduce spin frustration, namely to make each layer ferromagnetic, to adopt a compromise 120° spin arrangement in each layer, or to have a magnetic structure with a vanishing sum of all second nearest-neighbour spin exchanges

    Slow oxidation of magnetite nanoparticles elucidates the limits of the Verwey transition

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    Magnetite (Fe3O4) is of fundamental importance as the original magnetic material and also for the Verwey transition near T_V = 125 K, below which a complex lattice distortion and electron orders occur. The Verwey transition is suppressed by strain or chemical doping effects giving rise to well-documented first and second-order regimes, but the origin of the order change is unclear. Here, we show that slow oxidation of monodisperse Fe3O4 nanoparticles leads to an intriguing variation of the Verwey transition that elucidates the doping effects. Exposure to various fixed oxygen pressures at ambient temperature leads to an initial drop to TV minima as low as 70 K after 45-75 days, followed by recovery to a constant value of 95 K after 160 days that persists in all experiments for aging times up to 1070 days. A physical model based on both doping and doping-gradient effects accounts quantitatively for this evolution and demonstrates that the persistent 95 K value corresponds to the lower limit for homogenously doped magnetite and hence for the first order regime. In comparison, further suppression down to 70 K results from inhomogeneous strains that characterize the second-order region. This work demonstrates that slow reactions of nanoparticles can give exquisite control and separation of homogenous and inhomogeneous doping or strain effects on an nm scale and offers opportunities for similar insights into complex electronic and magnetic phase transitions in other materials.Comment: 24 pages, 13 figures, 2 tables, the manuscript is accepted for publishing at Nature Communication

    包括的凝固/線溶動態に基づく敗血症性DIC(播種性血管内凝固)の病態解明

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    Background: The functional dynamics of coagulation and fibrinolysis in patients with disseminated intravascular coagulation (DIC) vary due to the pathology and severity of various underlying diseases. Conventional measurements of hemostasis such as thrombin-antithrombin complex, plasmin-α2-plasmin-inhibitor complex, and fibrinogen-fibrin degradation products may not always reflect critical pathophysiologic mechanisms in DIC. This article aims to clarify the pathology of sepsis-associated DIC using assessment of comprehensive coagulation and fibrinolysis. Methods: Plasma samples were obtained from 57 patients with sepsis-associated DIC at the time of initial diagnosis. Hemostasis parameters were quantified by clot-fibrinolysis waveform analysis (CFWA) and thrombin/plasmin generation assays (T/P-GA). The results were expressed as ratios relative to normal plasma. Results: CFWA demonstrated that the maximum coagulation velocity (|min1|) ratio modestly increased to median 1.40 (min - max: 0.10 - 2.60) but the maximum fibrinolytic velocity (|FL-min1|) ratio decreased to 0.61 (0 - 1.19). T/P-GA indicated that the peak thrombin (Th-Peak) ratio moderately decreased to 0.71 (0.22 - 1.20), whereas the peak plasmin (Plm-Peak) ratio substantially decreased to 0.35 (0.02 - 1.43). Statistical comparisons identified a correlation between |min1| and Th-Peak ratios (ρ = 0.55, p < 0.001), together with a strong correlation between |FL-min1| and Plm-Peak ratios (ρ = 0.71, p < 0.001), suggesting that CFWA reflected the balance between thrombin and plasmin generation. With |min1| and |FL-min1| ratios, DIC was classified as follows: coagulation-predominant, coagulation/fibrinolysis-balanced, fibrinolysis-predominant, and consumption-impaired coagulation. The majority of patients in our cohort (80.7%) were coagulation-predominant. Conclusion: A pathological clarification of sepsis-associated DIC based on the assessment of coagulation and fibrinolysis dynamics may be useful for the hemostatic monitoring and management of optimal treatment in these individuals.博士(医学)・甲第786号・令和3年3月15日© 2020. Thieme. All rights reserved.This is a non-final version of an article published in final form in "http://dx.doi.org/10.1055/s-0040-1713890

    Multi- k spin ordering in CaFe<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> stabilized by spin-orbit coupling and further-neighbor exchange

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    Orthogonal spin ordering is rarely observed in magnetic oxides because nearest-neighbor symmetric Heisenberg superexchange interactions usually dominate. We have discovered that in the quadruple perovskite CaFe₃Ti₄O₁₂, where only the S = 2 Fe²⁺ ion is magnetic, long-range magnetic order consisting of an unusual arrangement of three interpenetrating orthogonal sublattices is stabilized. Each magnetic sublattice corresponds to a set of FeO₄ square planes sharing a common orientation. This multi-k magnetic spin ordering is the result of fourth-neighbor spin couplings with a strong easy-axis anisotropy. In an applied magnetic field, each sublattice tends towards ferromagnetic alignment, but remains polarized by internal magnetic fields generated by the others, thus stabilizing in a noncollinear canted ferromagnetic structure. CaFe₃Ti₄O₁₂ provides a rare example of how nontrivial long-range spin order can arise when near-neighbor Heisenberg superexchange is quenched

    Changes in Image Examinations at the Department of Oral Radiology : The Number of Intraoral and Panoramic Radiographs

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    After the computed radiography (CR) system was developed in 1986, it became possible to acquire, view and save digital images for medical diagnosis. Around that time, panoramic radiography was digitized by the CR system, but it was limited to large hospitals. From 1994, it has been digitized at large hospitals and dental clinics. We examined the changes in the number of intraoral and panoramic radiographs in dentistry, and based on the relationships among the numbers of radiographs, patients and dental operations, we discussed the clinical significance of digitization. We extracted intraoral and panoramic radiography data, the number of dental operations and the number of patients from the database of Tokushima University Hospital from 2002 to 2017. Then, we extracted nationwide data from Statistics of Medical Care Activities in Public Health by the Ministry of Health, Labour and Welfare from 2002 to 2017. As a result, although the numbers of patients and dental operations at Tokushima University Hospital have remained constant, the number of intraoral radiographs has decreased (72%), whereas the number of panoramic radiographs has increased annually since 2011 (131%). In addition, although the number of patients and nationwide insurance points increased in a different manner than that at Tokushima University Hospital, a decrease in the number of intraoral radiographs and an increase in the number of panoramic radiographs were noted across Japan. As panoramic imaging has been improved and adapted to different settings, panoramic radiography has been used instead of intraoral radiography, and it has been widely used in screening applications such as for perioperative patients. Although digitization is progressing, the analog images are still used (intraoral radiography analog rate, 29.7%, panoramic radiography analog rate, 12.4% in 2017)
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