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排序方式: 共有263条查询结果,搜索用时 171 毫秒
11.
Y Yamane R Tohno-oka S Yamada S Furuya K Shiokawa Y Hirabayashi H Sugino K Sugahara 《Canadian Metallurgical Quarterly》1998,273(13):7375-7381
Enzymatic elimination of heparan sulfate (HS) causes abnormal mesodermal and neural formation in Xenopus embryos, and HS plays an indispensable role in establishing the embryogenesis and tissue morphogenesis during early Xenopus development (Furuya, S., Sera, M., Tohno-oka, R., Sugahara, K., Shiokawa, K., and Hirabayashi, Y. (1995) Dev. Growth Differ. 37, 337-346). In this study, HS was purified from Xenopus embryos to investigate its disaccharide composition and binding ability to basic fibroblast growth factor (bFGF) and follistatin (FS), the latter being provided in two isoforms with core sequences of 315 and 288 amino acids (designated FS-315 and FS-288) originating from alternative mRNA splicing. Disaccharide composition analysis of the purified Xenopus HS showed the preponderance of a disulfated disaccharide unit with uronic acid 2-O-sulfate and glucosamine 2-N-sulfate, which has been implicated in the interactions with bFGF. Specific binding of the HS to bFGF and FS-288, the COOH-terminal truncated form, was observed in the filter binding assay, whereas HS did not bind to FS-315, indicating that the acidic Glu-rich domain of FS-315 precluded the binding. The binding of the HS to bFGF or FS-288 was markedly inhibited by heparin (HP) and various HS preparations, but not by chondroitin sulfate, supporting the binding specificity of HS. The binding specificity was further investigated using FS-288 and bovine intestinal [3H]HS. Competitive inhibition assays of the HS binding to FS-288 using size-defined HP oligosaccharides revealed that the minimum size required for significant inhibition was a dodecasaccharide, which is larger than the pentasaccharide required for bFGF binding. The binding affinity of FS to HS increased in the presence of activin, a growth/differentiation factor, which could be inactivated by direct binding to FS. These results, taken together, indicate that the structural requirement for binding of HS to bFGF and FS is different. HS may undergo dynamic changes in its structure during early Xenopus embryogenesis in response to the temporal and spatial expression of various growth/differentiation factors. 相似文献
12.
13.
Hideki Ono-Nakazato Kenji Taguchi Tateo Usui Keishi Tamura Yuuji Tomatsu 《Metallurgical and Materials Transactions B》2001,32(6):1113-1118
The standard Gibbs energies of formation of Cr2N and CrN have been measured by an equilibration technique and by using thermogravimetry and differential thermal analysis
(TG-DTA) at temperatures ranging from 1232 to 1523 K. The results are expressed as follows:
The standard Gibbs energies of formation of Cr2N and CrN determined by the present work are more negative than the values in the JANAF Tables by about 14 and 5 kJ/mol, respectively,
in the measured temperature range. 相似文献
14.
N. Fujiwara A. Ogaw Yu. Pestov R. Sugahara 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,240(2):275-283
Characteristics of fast pulse propagation in a large planar spark counter (PSC) are simulated using a pulser located inside the spark gap. Besides the main mode of pulse propagation, three undesirable modes are observed. These latter strongly distort the shape of the pulse. Characteristics of these modes and methods to eliminate their effects are demonstrated. We present an electrical design for a 120 cm spark counter along with some of its electrical properties as revealed by measurements made with the inner spark pulser. In the present counter design the charge of a pulse is shared by several neighboring strips, enabling one to measure the transverse position of a spark to a high degree of accuracy. 相似文献
15.
Yuuki Matsumoto Hiroshi Miyauchi Takashi Makino Takeshi Sugahara Kazunari Ohgaki 《Chemical engineering science》2011,(12):2672
Methane+ethane+1,1-dimethylcyclohexane+water system was investigated by using Raman spectroscopy and isothermal phase equilibrium measurements under four-phase (gas+aqueous+large guest species+hydrate phases) equilibrium conditions at 288.15 K. The results suggest that three kinds of hydrate structures emerge at 288.15 K in the methane+ethane+1,1-dimethylcyclohexane+water system. The hydrate structure for this system changed from structure-H to structure-I via structure-II with increase in the mole ratio of ethane to methane. 相似文献
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17.
Yasuhisa Oda Ken Kajiwara Koji Takahashi Atsushi Kasugai Michael A. Shapiro Richard J. Temkin Keishi Sakamoto 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(8):949-957
The preliminary results of mode measurement in the ITER relevant 40 m long transmission test line composed from 63.5 mm diameter
corrugated waveguides and miter bends are presented. The field patterns were measured by taking temperature profiles on a
paper screen placed in front of the waveguide end using an infrared imaging camera. The complex electric field at the waveguide
end was retrieved from the measured temperature profiles. As a result, the transmission power includes 87% of HE11 mode and 6% of LP11 odd (HE21+TE01) mode and small ratios of other modes. The mode content had small dependence on length of the transmission line. This result
indicated that the higher order mode content generated at the input of the transmission line is conserved and propagated through
the transmission line. This suggests that the initial RF coupling to the waveguide is critical since it affects the launcher
efficiency. 相似文献
18.
Akane Samizo Makoto Minohara Naoto Kikuchi Kenta Ando Yuta Mazuka Keishi Nishio 《Journal of the American Ceramic Society》2023,106(2):1540-1546
Sn2Nb2−xTaxO7 (x = 0.0–2.0) with pyrochlore structure is a promising material for p-type oxide semiconductors. A systematic study of its Nb/Ta ratio indicated that the hole–generation efficiency of the Nb end (Sn2Nb2O7) was an order of magnitude lower than that of the Ta end (Sn2Ta2O7). Although this occurs due to differences in oxygen-vacancy formation, the origins of the hole–generation efficiencies remain unclear due to limited information on local and global crystal-structure disorders in pyrochlore Sn2Nb2O7 and Sn2Ta2O7. In this study, the crystal structures of Sn2B2O7 (B = Nb, Ta), composed of BO6 octahedra and Sn4O tetrahedra, were investigated using X-ray absorption spectroscopy and X-ray diffraction. A detailed investigation of the local and global crystal structures indicated a larger amount of disorder in the Sn4O tetrahedra in Sn2Nb2O7 compared to Sn2Ta2O7; disorder in the BO6 octahedra occurred only in Sn2Ta2O7. This study indicates that an appropriate selection of the B-site element is vital for suppressing defect and disorder formation in Sn4O tetrahedra and subsequently improving the hole–carrier–generation efficiency. 相似文献
19.
Antioxidant Effects of Herbal Tea Leaves from Yacon (Smallanthus sonchifolius) on Multiple Free Radical and Reducing Power Assays,Especially on Different Superoxide Anion Radical Generation Systems
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Shintaro Sugahara Yuto Ueda Kumiko Fukuhara Yuki Kamamuta Yasushi Matsuda Tatsuro Murata Yasuhiro Kuroda Kiyotaka Kabata Masateru Ono Keiji Igoshi Shin Yasuda 《Journal of food science》2015,80(11):C2420-C2429
Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot‐water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot‐water extract was similarly demonstrated among these extracts. Varying concentrations of the hot‐water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC50 28.1 μg/mL), 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) cation radical (EC50 23.7 μg/mL), galvinoxyl radical (EC50 3.06 μg/mL), and chlorpromazine cation radical (EC50 475 μg/mL). The yacon tea‐leaf extract further demonstrated superoxide anion (O2?) radical scavenging effects in the phenazine methosulfate‐NADH‐nitroblue tetrazolium (EC50 64.5 μg/mL) and xanthine oxidase assay systems (EC50 20.7 μg/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea‐leaf extract could suppress the cellular O2? radical generation (IC50 65.7 μg/mL) in a phorbol 12‐myristate 13‐acetate‐activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O2? radical‐mediated disorders. 相似文献
20.
We propose a preconditioning scheme for diagonalizing large Hamiltonian matrices arising in first-principles plane-wave pseudopotential calculations. The new scheme is based on the Neumann expansion for the inverse, shifted Hamiltonian from which only a nonlocal part is omitted. The preconditioner is applied to a gradient vector using the fast Fourier transformation technique. In the framework of the Davidson-type diagonalization algorithm, we have found the present preconditioning scheme to be more efficient than widely accepted diagonal scaling methods. 相似文献