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排序方式: 共有395条查询结果,搜索用时 765 毫秒
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2.
Junya Kondoh Yoichi Tomii Katsuhiro Kawachi 《Journal of the American Ceramic Society》2003,86(12):2093-2102
Methods of suppressing decreased conductivity in 8 mol% Y2 O3 -stabilized–92 mol% ZrO2 (8YSZ) with aging were investigated. Different amounts of Sc2 O3 were doped into 8YSZ. The electrochemical properties of Sc2 O3 -doped 8YSZ were measured, and the microstructural and local structural changes were characterized. The present results indicate that an appropriate amount of Sc2 O3 doping, 3 or 4 mol%, effectively suppresses decreased conductivity with aging in 8YSZ. 相似文献
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The microstructure and indentation response of pressureless-sintered - and -SiC were studied using a high-resolution electron microscope and analytical electron microscopy. The materials were manufactured with boron and carbon as sintering aids. It was found that the overall porosity of the materials was very low but a large number of carbon inclusions were present. X-ray diffraction revealed the fabricated -SiC material was of the same 3C polytype as the initial starting powder; however, electron microscope observations indicated that the material contained a high density of faulting of the -forms. High-resolution imaging of grain boundaries in these materials indicated that the boundaries were very clean, and when they contained an amorphous intergranular film it was at most 0.5 to 1 nm thick. The presence of boron was not detected. Deformation due to identation took several forms. Firstly, radial cracks extending from the corners of the indent suffered little hindrance from the matrix microstructure, such that transgranular fracture was the dominant mode. Secondly, the deformation zone beneath the indentations showed copious lattice microcracks with some preferred orientation during crack formation and propagation. 相似文献
5.
Sachi Oshima Shunichi Asai Naohiko Seki Chikashi Minemura Takashi Kinoshita Yusuke Goto Naoko Kikkawa Shogo Moriya Atsushi Kasamatsu Toyoyuki Hanazawa Katsuhiro Uzawa 《International journal of molecular sciences》2021,22(12)
We identified the microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC) tissues by RNA sequencing, in which 168 miRNAs were significantly upregulated, including both strands of the miR-31 duplex (miR-31-5p and miR-31-3p). The aims of this study were to identify networks of tumor suppressor genes regulated by miR-31-5p and miR-31-3p in HNSCC cells. Our functional assays showed that inhibition of miR-31-5p and miR-31-3p attenuated cancer cell malignant phenotypes (cell proliferation, migration, and invasion), suggesting that they had oncogenic potential in HNSCC cells. Our in silico analysis revealed 146 genes regulated by miR-31 in HNSCC cells. Among these targets, the low expression of seven genes (miR-31-5p targets: CACNB2 and IL34; miR-31-3p targets: CGNL1, CNTN3, GAS7, HOPX, and PBX1) was closely associated with poor prognosis in HNSCC. According to multivariate Cox regression analyses, the expression levels of five of those genes (CACNB2: p = 0.0189; IL34: p = 0.0425; CGNL1: p = 0.0014; CNTN3: p = 0.0304; and GAS7: p = 0.0412) were independent prognostic factors in patients with HNSCC. Our miRNA signature and miRNA-based approach will provide new insights into the molecular pathogenesis of HNSCC. 相似文献
6.
Katsuhiro Harada 《应用聚合物科学杂志》1981,26(6):1961-1973
The decomposition of poly(methyl methacrylate) (PMMA), as a positive resist, in CF4/O2 plasma etching has been studied in the thin film state in order to clarify the factors influencing the dry etching durability of resists. It becomes clear that the major PMMA decomposition in CF4/O2 plasma etching proceeds by the mechanism of random chain scission because very small kinetic chain lengths are estimated from the gel permeation chromatography data. The Arrhenius plots for the plasma etching rate of PMMA bend above about the glass transition temperature (Tg), where rapid increase of the etching rate and remarkable pattern deformation are observed. Activation energy of the PMMA etching rate which is changed by oxygen concentration and rf power indicates various values from 3.1 to 6.5 kcal/mol below about Tg. The result of molecular weight variation in the cross section of the film suggests that the active species permeate into the film with fairly large speed and the PMMA decomposition occurs not only at the film surface but also at deep layer of the film. 相似文献
7.
Shigeru Sugiyama Kiyozumi Sato Seiji Yamasaki Katsuhiro Kawashiro Hiromu Hayashi 《Catalysis Letters》1992,14(1):127-133
Silica-supported alkaline earth oxides revealed excellent activity to convert acetic acid selectively into acetone in a vapor-phase fixed-bed flow system. Acetone was obtained through the cyclic formation of alkaline earth acetate followed by decomposition. Magnesium oxide should be supported on the silica surface without formation of magnesium silicate, which was inactive for the present reaction. Attempted syntheses of benzophenone and acetophenone are also described. 相似文献
8.
Katsuhiro Inomata Daisuke NakanishiAi Banno Eiji NakanishiYosuke Abe Ryuta KuriharaKentaro Fujimoto Takuhei Nose 《Polymer》2003,44(18):5303-5310
Association behavior and physical gelation mechanism of ABA triblock copolymer dissolved in B-selective solvent have been studied systematically from dilute to moderately concentrated solutions. Static and dynamic light scattering and nuclear magnetic resonance measurements for dilute solutions of poly(methyl methacrylate)-block-poly(tert-butyl acrylate)-block-poly(methyl methacrylate) (PMMA-PtBuA-PMMA) in 1-butanol (PtBuA selective solvent) indicated that PMMA-PtBuA-PMMA chains are molecularly dissolved above 50 °C. With decreasing temperature, the triblock copolymers form associated micelles consisting PMMA associated core and PtBuA shell. Linear dynamic viscoelastic measurements for solutions with moderate concentration (3.9-12.0 wt%) revealed that the system was viscous sol state at 60 °C. Drastic increase of shear storage modulus (G′) occurred with decreasing temperature, and at 25 °C, G′ showed rubbery plateau with weak frequency dependency, means the formation of elastic physical gel. The consistency between the temperature for micelle formation and that at the increase in G′ indicates that the physical gelation is owing to the network formation as the result of the association of PMMA chains and the bridging PtBuA chains connecting the PMMA cores. Master curves for the dynamic moduli were derived by time-temperature superposition along the frequency axis. Just above sol-gel transition concentration (Cgel), the master curves suggest the existence of fairy amount of aggregate that is not incorporated in the macroscopic network. With the increase in polymer concentration, the master curves become to reveal Maxwell-type viscoelasticity with narrow relaxation time distribution, suggesting the formation of transient network with easily generation and destruction of crosslinks. Concentration dependency of the plateau modulus is stronger than the theoretically expected, means the macroscopic transient network grows with polymer concentration by increasing the fraction of elastically effective bridging PtBuA chain above Cgel. 相似文献
9.
Kiyohiko Hattori Eri Homma Toshinori Kagawa Masayuki Otani Naoki Tatebe Yasunori Owada Lin Shan Katsuhiro Temma Kiyoshi Hamaguchi 《Artificial Life and Robotics》2016,21(4):451-459
Recently, many extensive studies have been conducted on robot control via self-positioning estimation techniques. In the simultaneous localization and mapping (SLAM) method, which is one approach to self-positioning estimation, robots generally use both autonomous position information from internal sensors and observed information on external landmarks. SLAM can yield higher accuracy positioning estimations depending on the number of landmarks; however, this technique involves a degree of uncertainty and has a high computational cost, because it utilizes image processing to detect and recognize landmarks. To overcome this problem, we propose a state-of-the-art method called a generalized measuring-worm (GMW) algorithm for map creation and position estimation, which uses multiple cooperating robots that serve as moving landmarks for each other. This approach allows problems of uncertainty and computational cost to be overcome, because a robot must find only a simple two-dimensional marker rather than feature-point landmarks. In the GMW method, the robots are given a two-dimensional marker of known shape and size and use a front-positioned camera to determine the marker distance and direction. The robots use this information to estimate each other’s positions and to calibrate their movement. To evaluate the proposed method experimentally, we fabricated two real robots and observed their behavior in an indoor environment. The experimental results revealed that the distance measurement and control error could be reduced to less than 3 %. 相似文献
10.
Yoshiaki Ukita Toshifumi Asano Kuniyo Fujiwara Katsuhiro Matsui Masahiro Takeo Seiji Negoro Yuichi Utsumi 《Microsystem Technologies》2008,14(9-11):1573-1579
The advantages of vertical microreactor stack with three-dimensional (3D) structure for immunoassay are discussed. The vertical microreactor stack uses vertical fluid flow operation with multifunctional fluid filters. The multi function of fluid filter is very effective for micromixing and passive valve operation. The mechanism of micromixing is discussed by using computational fluid dynamics (CFD), and we know that the mixing mechanism based on Coanda effect. To evaluate the micromixing performance of fluid filter, we demonstrated enzyme reaction with unique repeat mixing operation. As the results, we proved that the fluid filter has very effective mixing performance. The detection limit, which demonstrated by competition enzyme-linked immunosorvent assay (ELISA), is comparable with recommended detection limit, which suggested by Japanese ministry for the environment. 相似文献