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52 result(s) for "Manabe, Takaaki"
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New sign of vacuum ultraviolet driven crystal growth in ternary oxide Zn 3 V 2 O 8 films
Ternary oxide Zn3V2O8 films was successfully formed on glass substrates only by means of vacuum ultraviolet irradiation to the spin-coated metal--organic solutions. From Fourier transform infrared spectroscopy measurements, we confirmed that the crystal growth proceeded at metal--organic bond cleavage under VUV irradiation. The crystalline size of the obtained materials was estimated to be 1.5--2.5 nm. The prepared Zn3V2O8 films clearly showed yellow luminescence, corresponding to a charge transfer transition in the VO4 tetrahedra.
New sign of vacuum ultraviolet driven crystal growth in ternary oxide Zn3V2O8 films
Ternary oxide Zn 3 V 2 O 8 films was successfully formed on glass substrates only by means of vacuum ultraviolet irradiation to the spin-coated metal–organic solutions. From Fourier transform infrared spectroscopy measurements, we confirmed that the crystal growth proceeded at metal–organic bond cleavage under VUV irradiation. The crystalline size of the obtained materials was estimated to be 1.5–2.5 nm. The prepared Zn 3 V 2 O 8 films clearly showed yellow luminescence, corresponding to a charge transfer transition in the VO 4 tetrahedra.
Effect of Prefiring Condition on the In-Plane Orientation of Epitaxial Oxide Films in Coating-Pyrolysis Process
Epitaxial α-Fe2O3 films were obtained by using iron 2-ethylhexanoate as a starting material. A coating solution was spun on α-Al2O3 single-crystal substrates, and prefiring and final heat-treatment at various temperatures in air or low oxygen partial pressure were carried out. The degree of in-plane orientation was estimated in terms of full width at half maximum of X-ray diffraction (XRD) φ-scans. The results of TG-DTA, IR, and XRD suggested that the optimum prefiring condition for obtaining highly epitaxial films is in the range 200–300°C which corresponds to removal of most of the organic component from the precursor, prior to crystallite formation of metal oxide. When the films were prefired at higher temperatures, different atmospheres in prefiring and final heat-treatment lowered the in-plane orientation of the films.
Preparation of epitaxial SrBi2Nb2O9 and SrBi2Ta2O9 thin films by the coating-pyrolysis process
Epitaxial and polycrystalline thin films of bismuth layer-structured ferroelectrics, SrBi2Nb2O9 (SBN) and SrBi2Ta2O9 (SBT), were prepared on single-crystal SrTiO3(001) and polycrystalline yttria-stabilized zirconia substrates, respectively, by the coating-pyrolysis process. The epitaxial relationship of the films and substrates was SBN, SBT (001)//SrTiO3(001) and SBN, SBT [100]//SrTiO3[100],[010], where pseudotetragonal indices were adopted for SBN and SBT. The lattices of the epitaxial films were found to be slightly strained owing to stress from the substrate. Atomic force microscopy observations showed that the epitaxial films as well as polycrystalline films consisted of round-shaped, islandlike grains of submicrometer size.
Ferroelectric Properties of (001)- and (106)-Oriented SrBi2Ta2O9 Epitaxial Thin Films
Epitaxially grown SrBi2Ta2O9 (SBT) thin films with (001) and (106) orientations were prepared on La-doped SrTiO3 (001) and (110) substrates, respectively, by coating-pyrolysis process. When the films were annealed in air, their epitaxy was poor and no significant difference was observed in the P-E characteristics for the films that have different orientations. By contrast, the crystallinity and epitaxy of the films increased with decreasing oxygen partial pressure, p(O2), of annealing atmosphere. Using these high quality epitaxial films, we observed a distinct difference in P-E hysteresis curves, which reflects the orientation of the films. After postannealing of these films in O2 to compensate for possible oxygen deficiency, which might have been introduced into the SBT films owing to low p(O2) annealing, the anisotropy of the ferroelectric response was maintained and almost the same P-E loops were obtained.
Generic phase diagram of \electron-doped\ T' cuprates
We investigated the generic phase diagram of the electron doped superconductor, Nd2-xCexCuO4, using films prepared by metal organic decomposition. After careful oxygen reduction treatment to remove interstitial Oap atoms, we found that the Tc increases monotonically from 24 K to 29 K with decreasing x from 0.15 to 0.00, demonstrating a quite different phase diagram from the previous bulk one. The implication of our results is discussed on the basis of tremendous influence of Oap \"impurities\" on superconductivity and also magnetism in T' cuprates. Then we conclude that our result represents the generic phase diagram for oxygen-stoichiometric Nd2-xCexCuO4.
Reduction dependence of superconductivity in undoped T' cuprates
We have recently achieved superconductivity in undoped T'-RE2CuO4 (RE: Pr, Nd, Sm, Eu, and Gd), using epitaxial thin films by metal organic decomposition. The key recipes to achieve superconductivity are low-PO2 firing and subsequent vacuum reduction to minimize the amount of impurity oxygen atoms, which are very harmful to high-Tc superconductivity. In this article, we report our investigation on the reduction dependence of superconductivity of T'-RE2CuO4. For thin films, the amount of remnant Oap atoms is difficult to evaluate but we propose that one good measure for this may be the c-axis lattice constant, which tells us whether the reduction is insufficient or excessive.
Superconductivity in undoped T' cuprates with Tc over 30 K
Undoped cuprates have long been considered to be antiferromagnetic insulators. In this article, however, we report that superconductivity is achieved in undoped T'-RE2CuO4 (RE = Pr, Nd, Sm, Eu, and Gd). Our discovery was performed by using metal-organic decomposition (MOD), an inexpensive and easy-to-implement thin-film process. The keys to prepare the superconducting films are firing with low partial-pressure of oxygen and reduction at low temperatures. The highest Tc of undoped T'-RE2CuO4 is over 30 K, substantially higher than \"electron-doped\" analogs. Remarkably, Gd2CuO4, even the derivatives of which have not shown superconductivity so far, gets superconducting with Tconset as high as ~ 20 K. The implication of our discovery is briefly discussed.
Identifying Bleeding Etiologies by Endoscopy Affected Outcomes in 10,342 Cases With Hematochezia: CODE BLUE-J Study
The bleeding source of hematochezia is unknown without performing colonoscopy. We sought to identify whether colonoscopy is a risk-stratifying tool to identify etiology and predict outcomes and whether presenting symptoms can differentiate the etiologies in patients with hematochezia. This multicenter retrospective cohort study conducted at 49 hospitals across Japan analyzed 10,342 patients admitted for outpatient-onset acute hematochezia. Patients were mostly elderly population, and 29.5% had hemodynamic instability. Computed tomography was performed in 69.1% and colonoscopy in 87.7%. Diagnostic yield of colonoscopy reached 94.9%, most frequently diverticular bleeding. Thirty-day rebleeding rates were significantly higher with diverticulosis and small bowel bleeding than with other etiologies. In-hospital mortality was significantly higher with angioectasia, malignancy, rectal ulcer, and upper gastrointestinal bleeding. Colonoscopic treatment rates were significantly higher with diverticulosis, radiation colitis, angioectasia, rectal ulcer, and postendoscopy bleeding. More interventional radiology procedures were needed for diverticulosis and small bowel bleeding. Etiologies with favorable outcomes and low procedure rates were ischemic colitis and infectious colitis. Higher rates of painless hematochezia at presentation were significantly associated with multiple diseases, such as rectal ulcer, hemorrhoids, angioectasia, radiation colitis, and diverticulosis. The same was true in cases of hematochezia with diarrhea, fever, and hemodynamic instability. This nationwide data set of acute hematochezia highlights the importance of colonoscopy in accurately detecting bleeding etiologies that stratify patients at high or low risk of adverse outcomes and those who will likely require more procedures. Predicting different bleeding etiologies based on initial presentation would be challenging.
The Major DNA Repair Pathway after Both Proton and Carbon-Ion Radiation is NHEJ, but the HR Pathway is More Relevant in Carbon Ions
The purpose of this study was to identify the roles of non-homologous end-joining (NHEJ) or homologous recombination (HR) pathways in repairing DNA double-strand breaks (DSBs) induced by exposure to high-energy protons and carbon ions (C ions) versus gamma rays in Chinese hamster cells. Two Chinese hamster cell lines, ovary AA8 and lung fibroblast V79, as well as various mutant sublines lacking DNA-PKcs (V3), X-ray repair cross-complementing protein-4 [XRCC4 (XR1), XRCC3 (irs1SF) and XRCC2 (irs1)] were exposed to gamma rays (137Cs), protons (200 MeV; 2.2 keV/μm) and C ions (290 MeV; 50 keV/μm). V3 and XR1 cells lack the NHEJ pathway, whereas irs1 and irs1SF cells lack the HR pathway. After each exposure, survival was measured using a clonogenic survival assay, in situ DSB induction was evaluated by immunocytochemical analysis of histone H2AX phosphorylation at serine 139 (γ-H2AX foci) and chromosome aberrations were examined using solid staining. The findings from this study showed that clonogenic survival clearly depended on the NHEJ and HR pathway statuses, and that the DNA-PKcs–/– cells (V3) were the most sensitive to all radiation types. While protons and γ rays yielded almost the same biological effects, C-ion exposure greatly enhanced the sensitivity of wild-type and HR-deficient cells. However, no significant enhancement of sensitivity in cell killing was seen after C-ion irradiation of NHEJ deficient cells. Decreases in the number of γ-H2AX foci after irradiation occurred more slowly in the NHEJ deficient cells. In particular, V3 cells had the highest number of residual γ-H2AX foci at 24 h after C-ion irradiation. Chromosomal aberrations were significantly higher in both the NHEJ- and HR-deficient cell lines than in wild-type cell lines in response to all radiation types. Protons and gamma rays induced the same aberration levels in each cell line, whereas C ions introduced higher but not significantly different aberration levels. Our results suggest that the NHEJ pathway plays an important role in repairing DSBs induced by both clinical proton and C-ion beams. Furthermore, in C ions the HR pathway appears to be involved in the repair of DSBs to a greater extent compared to gamma rays and protons.