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排序方式: 共有289条查询结果,搜索用时 31 毫秒
61.
Sotaro Mori Takuji Kurimoto Hidetaka Maeda Makoto Nakamura 《International journal of molecular sciences》2021,22(1)
This study aimed to verify whether dimethyl fumarate (DMF) promotes the survival of retinal ganglion cells (RGCs) after optic nerve crush (ONC) accompanied by activation of the NF-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. We examined changes in the densities of tubulin β3 (TUBB3)-positive RGCs and the amplitudes of the positive scotopic threshold response (pSTR), reflecting the functional activity of RGCs, recorded on an electroretinogram, with daily administration of DMF, on day 7 after ONC. Furthermore, immunohistochemical and immunoblotting analyses were performed to study the activation of the Nrf2/HO-1 pathway using retinas treated with daily administration of DMF. Daily administration of DMF increasedthe density of TUBB3-positive RGCs in a dose-dependent fashion and significantly increased the amplitude of the pSTR. Immunohistochemical analysis showed that DMF administration increased the immunoreactivity for Nrf2 and HO-1, a potent antioxidant enzyme, in RGCs immunolabeled with RNA-binding protein with multiple splicing (RBPMS). Immunoblotting analysis revealed an increase in the nuclear expression of Nrf2 and marked upregulation of HO-1 after DMF administration. These results suggest that DMF has survival-promoting effects in RGC after ONC, possibly via the Nrf2/HO-1 pathway. 相似文献
62.
N Yabuki H Sasano M Tobita A Imatani T Hoshi K Kato S Ohara S Asaki T Toyota H Nagura 《Canadian Metallurgical Quarterly》1997,151(3):821-829
Helicobacter pylori (HP) infection, a cause of multifocal atrophic gastritis, is considered an important factor related to the evolution of the human gastric mucosa from normal to intestinal-type adenocarcinoma. We examined cell proliferation and both double and single strand DNA damage in situ in 35 patients undergoing gastrectomy for adenocarcinoma with HP-infected gastric mucosa by immunolocalization of Ki-67, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling, and in situ nick translation. We also studied the distribution of intraepithelial neutrophils by elastase immunolocalization. HP infection was confirmed in all cases by serum anti-HP antibodies, ureas testing, and histopathological examination. HP-infected gastric mucosa was classified according to the degree of inflammation and intestinal metaplasia. Ki-67, terminal deoxynucleotidyl transferase-mediated labeling, in situ nick translation, and intraepithelial neutrophil indices all increased with the progression of gastritis and were highest in glands with incomplete intestinal metaplasia. All indices were lowest in gastric glands with complete intestinal metaplasia. Significant positive correlations were observed among these markers. Increased proliferative activity in HP-associated chronic gastritis in response to cell damage or injury was clearly demonstrated, suggesting that both HP-associated toxins and intraepithelial neutrophils are important in HP-related gastric epithelial injury. Increased cell turnover associated with incomplete intestinal metaplasia may result in DNA instability and subsequent development of intestinal-type gastric adenocarcinoma in HP-infected mucosa. 相似文献
63.
Yoji Koike Shuichi Takeuchi Hidetaka Sato Yuichiro Hama Masatsune Kato Yasuhiro Ono Susumu Katano 《Journal of Low Temperature Physics》1996,105(3-4):317-322
The effects of substitution of Y or Bi on the low-temperature structural phase transition, electronic anomaly and superconductivity have been studied in La2-y-xYyBaxCuO La2-y-xBiyBaxCuO4 and La1.9-y-xTb0.1BiySrxCuO4 with x = 1/8. Moreover, an electronic anomaly, which is analogous to those observed in La2–xBaxCuO4 and La1.6-xNd0.4SrxCuO4 with x 1/8, has been found below about 60 K in the thermoelectric power measurements for the Zn-substituted La2–xSrxCu1–yZnyO4 with x 0.115 and y = 0.01 – 0.02. These experimental results support the conclusions by Tranquada et al. that static order of the stripe correlations of holes and spins, owing to pinning by the low-temperature structure or impurities (Zn in this case), is the origin of the electronic anomaly, leading to the suppression of superconductivity. 相似文献
64.
Tadayoshi Matsumori Atsushi Kawamoto Tsuguo Kondoh Tsuyoshi Nomura Hidetaka Saomoto 《Structural and Multidisciplinary Optimization》2017,56(3):619-629
This paper deals with a design method for boundary shapes using filtering techniques based on a partial differential equation (PDE). In shape optimization, it is known that oscillatory boundaries appear when design variables are directly assigned to the design boundaries. In addition, during the optimization process, discretized elements in a computational domain are distorted due to extremely large shape changes along the design boundaries. The distorted elements may cause accuracy deterioration or numerical instability in a forward problem. In this paper, we propose a shape optimization method by using the PDE as a low pass filter which prevents the oscillatory boundaries of the optimized design. For restricting the shape distortion of the discretized elements, the shear deformation of the elements is constrained in the optimization problem. Mathematical programming is used to find the boundary shapes under the KKT conditions. The effectiveness of the proposed method is demonstrated through numerical examples in solid and fluid mechanics. 相似文献
65.
Effect of the (Ba + Sr)/Ti ratio on the microwave‐tunable properties of Ba0.6Sr0.4TiO3 ceramics
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Takashi Teranishi Riku Kanemoto Hidetaka Hayashi Akira Kishimoto 《Journal of the American Ceramic Society》2017,100(3):1037-1043
The impact of the (Ba + Sr)/Ti (A/B) ratio on the microwave‐tunable characteristics of diffuse phase transition (DPT) ferroelectric Ba0.6Sr0.4TiO3 (0.6‐BST) ceramics was investigated. The reduction in the lattice constant with increasing nonstoichiometry was attributed to introduced partial Schottky defects, i.e., and . The magnitude of the dielectric constant, ε′, at room temperature in the absence of an applied electric field was governed by the shift in the dielectric maximum temperature, Tm, because Tm was close to room temperature for the 0.6‐BST. The dielectric loss, tanδ, diminished as the ε′ decreased for 0.98≤A/B≤1.05, while the tanδ was much higher for A/B=0.95 having the greatest A‐site vacancy loading. The negatively charged and were mainly compensated by oxygen vacancies and likely partly compensated by holes, h?, which contributed to the electrical conduction. The tunability, T, at 100 MHz was almost constant at 20%–25% for A/B≥1.00 despite the reduction of the ε′, whereas T decreased for A/B<1.00 to ca. 10% for A/B=0.95 having the greatest A‐site vacancy loading. The results implied that the for larger A/B values was more efficient in generating nucleation sites in the polar nanoregions (PNRs) than the for smaller A/B values, thereby providing greater dipole polarization. Consequently, the figure of merit, FOM, reached its maximum of 250 at A/B=0.9875, which was ca. 155% higher than that of the stoichiometric BST. 相似文献
66.
67.
Hidetaka Uehara Tomomi Suganuma Satoshi Negishi Satoru Ueno Kiotaka Sato 《Journal of the American Oil Chemists' Society》2006,83(3):261-267
Conjugated linoleic acid (CLA) is commercially available as a mixture consisting of almost equal amounts of the cis-9,trans-11-CLA (c9, t11) and trans-10, cis-12-CLA (t10, c12) isomers. Separation of the two isomers is highly significant since each exhibits different biochemical properties. Highly
efficient separation could be accomplished by crystallization in acetone (solvent) of the two CLA isomers (solutes) in the
presence of medium-chain fatty-acid (MCFA) additives. The relative concentration ratios of the two CLA isomers in the solvent-crystallized
materials varied depending on which MCFA were added. Addition of lauric and decanoic acids resulted in the crystals predominantly
containing t10,c12, whereas octanoic acid yielded those predominantly containing c9,t11. We have confirmed that onetime solvent crystallization using decanoic acid and octanoic acid additives increased the t10,c12 and c9,t11 concentrations, and that repeated solvent crystallization resulted in the ratio of c9,t11 to t10,c12 of at least 4∶96 or 98∶2. 相似文献
68.
To prepare hard and transparent poly (methyl methacrylate)‐silica coat film on glass or polycarbonate substrates, poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) random copolymers and perhydropolysilazane (PHPS) were blended in solution. Then the solution was cast on the substrates. The grafting of PHPS onto 2‐hydroxyethyl methacrylate unit was analyzed by 1H NMR spectroscopy. Surface hardness and transparency of the coat film were measured by nano‐indentation method and UV‐Vis spectroscopy, respectively. Surface hardness of coat film depended on the volume fraction of silica in the coat film, and reached 2.7 GPa when the volume fraction of silica was 76.4%. Transparency of the coat films prepared with PHPS was almost 100%, indicating that the coat film prepared with PHPS was highly transparent not only on glass substrate but also on the polycarbonate substrate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
69.
Mass spectrometry was used to monitor in-situ gaseous species that were generated at the head-disk interface (HDI) in a high vacuum. It was found that the end groups of the lubricants significantly affected the wear durability at the HDI; piperonyl (–CH2-phe = (O)2 = CH2) terminated Fomblin AM3001 lubricant exhibited longer life than hydroxyl (–OH) terminated Fomblin ZDOL lubricant. The continuous removal of the lubricants resulted in a continuously increasing friction coefficient. Further, the characteristics of tribochemical reactions of the lubricants (Fomblin Z series) with different end groups was investigated in details using Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) just after the sliding tests. It was found that the decomposition of the end groups was more significant than that of the backbone. The lubricants terminated with the following groups showed the following order of increasing decomposition: –CH2O-CH2-phe = (O)2 = CH2 (AM3001), –CH2OH (ZDOL) < –CH2OCH2CH(OH)CH2OH (Z Tetraol) < –CH2(OCH2CH2)nOH (ZDOL-TX), –COOH (Z Diac). The decomposition of the lubricants appeared to start from the end groups. 相似文献
70.
It has been found that CF3CH2F (HFC-134a) gas is an effective lubricant for several ceramics because of the formation of fluorine-containing tribochemical products. To understand the influence of the molecular structure of fluorine-containing gases on the lubricating characteristics, the lubricating effects and tribochemical reactions of some fluorinated methanes for Al2O3 ceramic were studied. X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) were used to identify the chemical structure of tribochemical products. It was found that the friction and wear of Al2O3 ceramic were dependent on the molecular structure of the reacting fluorocarbon gases. The lowest friction was obtained in CH2F2. CHF3 showed the best anti-wear effect. The results of surface analyses indicate that greater amounts of tribochemical products are produced when Al2O3 rubs in CH2F2 than in CF4 and CHF3 gases. C–C/C–H/carbon and AlF3, which are mainly formed on the sliding surface in CH2F2, are responsible for the low friction. The mechanism of tribochemical reactions of the different environmental molecules on the nascent surface of Al2O3 was also discussed. 相似文献