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排序方式: 共有599条查询结果,搜索用时 0 毫秒
1.
Genki Saito Yuji Kunisada Takumi Watanabe Xuemei Yi Takahiro Nomura Norihito Sakaguchi Tomohiro Akiyama 《Journal of the American Ceramic Society》2019,102(1):524-532
Carbon-and-oxygen-doped AlN specimens were prepared by combustion synthesis using Al, graphite, and AlN. Graphite addition changed the product color from white to blue. By XRD, the lattice constant increased slightly with increasing carbon content. Blue AlN powder was synthesized with a molar ratio of the diluent AlN of 0.2-0.5 with a fixed graphite content of 0.05. At an AlN molar ratio exceeding 0.6, carbon was not successfully incorporated due to the lower reaction temperature. Calcination at 800°C in air removed residual graphite without changing the crystal structure or product color. Oxygen, nitrogen, and carbon analyses revealed that blue AlN powders contained 0.45-0.54 mass% carbon and 1.4-1.6 mass% oxygen, while the undoped AlN contained 0.021 mass% carbon and 0.94 mass% oxygen. The origin of the white-to-blue color change was investigated via reflection measurements. Blue AlN exhibits an absorption peak at 634 nm (1.96 eV). From first-principles electronic structure calculations, the C-doped AlN and carbon-and-oxygen-doped AlN with a 1:1 ratio could be classified as p-type, whereas the O-doped AlN and 1:3 carbon-and-oxygen-doped AlN were n-type. One reason for the absorption peak at 634 nm may be a transition from the conduction band to an upper unoccupied state. These results suggest the possible control of optical and electronic properties of AlN via carbon-and-oxygen doping. 相似文献
2.
The In-site of Ba2In2O5 with Brownmillerite structure was partially substituted for Ce4+ ions in order to examine the doping effect on the order-disorder transition. Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.1, 0.2, 0.3, 0.5, 1.0, and 1.5) were prepared by solid state reaction. X-Ray diffraction analyses of these powder samples demonstrated that Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.1 and 0.2) possesses Brownmillerite structure. With increasing content of Ce4+ ion the crystal system of Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.3, 0.5, and 1.0) changed to cubic perovskite structure above the order-disorder transition temperature of Ba2In2O5. Arrhenius plots of the electrical conductivities of Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.2, 0.3, and 1.0) exhibited no discontinuity. These compounds had high transference numbers of oxide ion above 973 k. 相似文献
3.
ABSTRACT A purified 160-kDa protein, isolated from the cuticle of kurama prawn and named melanosis collaborating factor (MCF), was a key factor in promoting melanosis by a cooperative reaction with hemocyanin-derived phenoloxidase but hemocyanin itself was incapable of producing black pigment. The enzymatic activity of MCF in the body of the prawn was very stable against the process of freezing and thawing; the enzyme maintained more than 80% of its activity after 3 mo of storage at −2 5 °C. These results indicated that MCF, acting in conjunction with hemocyanin-derived phenoloxidase, played a crucial role in postharvest melanogenesis in prawn. 相似文献
4.
H Uchiyama T Obata T Tsubaki N Sakaguchi Y Iikura T Aoki 《Canadian Metallurgical Quarterly》1995,44(2):70-76
In our Department, continuous isoproterenol inhalation therapy has been conducted on status asthmatics over the last 10 years. In the present study, we investigated whether there are any differences in the therapeutic efficacy of continuous inhalation of isoproterenol in the presence or absence of respiratory infections which may induce or aggravate asthma attacks. The treatment period was significantly longer in patients with pneumonia. Further prolongation of the treatment period was noted in patients with atelectasis. However, there were no apparent differences in therapeutic efficacy according to age or the severity of attacks. These findings suggest that continuous inhalation of isoproterenol is very effective for status asthmatics if respiratory infections are thoroughly controlled. 相似文献
5.
N. Murayama M. Awano Y. Kodama S. Sakaguchi F. Wakai 《Journal of Materials Science》1992,27(13):3642-3644
Bi0.85Pb0.15Sr0.8CaCu1.4O
y
superconductor was quenched to room temperature after annealing at several temperatures in air. From the initial magnetization curve measurement for the annealed samples, it was found that the volume fraction of superconducting phases of the sample annealed at 650°C greatly decreased. TEM observation revealed that a second phase often appeared in the grain-boundary region for the sample annealed at 700°C. The second phase was identified as Bi1Pb2Sr2.6Ca1.6O
y
by energy dispersive spectroscopy. 相似文献
6.
Y Nakamura Y Horii T Nishino H Shiiki Y Sakaguchi T Kagoshima K Dohi Z Makita H Vlassara R Bucala 《Canadian Metallurgical Quarterly》1993,143(6):1649-1656
Advanced glycosylation end products (AGEs) accumulate on long-lived extracellular matrix proteins and have been implicated in the micro- and macrovascular complications of diabetes mellitus. Within the arterial wall, AGE-modified proteins increase vascular permeability, inactivate nitric oxide activity, and induce the release of growth-promoting cytokines. Recently developed anti-AGE antibodies were used in an immunohistochemical analysis of coronary arteries obtained from type II diabetic and nondiabetic patients. High levels of AGE reactivity were observed within the atherosclerotic plaque present in vessels from selected patients with diabetes. Considered together with the pathological effects of AGEs on vascular wall homeostasis, these data support the role of advanced glycosylation in the rapidly progressive atherosclerosis associated with diabetes mellitus. 相似文献
7.
A new spectral attenuation measurement system using a Fourier transform spectrometer is developed. The Fourier transform spectral attenuation measurement (FT-SAM) system makes the signal acquisition time for a wide wave-length range of 1.0?4.2? much shorter than measurement with a conventional dispersive spectral attenuation measurement system. The spectral attenuation for a fluoride glass single-mode fibre, with a minimum loss of 3±1 dB/km at 2.5?m, is measured with this system. 相似文献
8.
K Sakaguchi JE Herrera S Saito T Miki M Bustin A Vassilev CW Anderson E Appella 《Canadian Metallurgical Quarterly》1998,12(18):2831-2841
9.
10.
Effect of Composition on the Oxygen Tracer Diffusion in Transparent Yttrium Aluminium Garnet (YAG) Ceramics 总被引:1,自引:0,他引:1
Isao Sakaguchi Hajime Haneda Junzo Tanaka Takakimi Yanagitani 《Journal of the American Ceramic Society》1996,79(6):1627-1632
The grain boundary structure and oxygen tracer diffusion in transparent yttrium aluminum garnet (YAG) ceramics varying from 2% excess of Y2 O3 to 0.5% excess of Al2 O3 were studied. The characterization of the specimens is as follows: (i) For the Y2 O3 -excess specimen, a second phase (yttrium aluminum perovskite: YAP) containing silicon in the grain boundary was found, (ii) For the Al2 O3 -excess specimen, both aluminum-rich particles (alumina) and a silicon-rich segregant layer were observed in the grain boundary. The volume diffusion of the oxygen tracer is little influenced by the excess composition. In contrast, the grain boundary diffusion of the oxygen tracer is suppressed in the Y2 O3 -excess specimens, compared to Al2 O3 -excess specimens. These differences are thought to result from the chemical reaction between the second phase and the intergranular liquid phase during the sintering. 相似文献