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排序方式: 共有940条查询结果,搜索用时 15 毫秒
931.
Setsuhisa Tanabe Naohiro Saga Kazuyuki Hirao Teiichi Hanada† 《Journal of the American Ceramic Society》1990,73(6):1733-1736
SiO2 –Al2 O3–Eu2 O3 glasses were prepared for the composition 50siO2 ·(50 – x )Al2 O3·x Eu2 O3 , and their density, sound velocity, and elastic modulus were measured. The chemical shift of the AIK a band emission spectra and the isomer shift of 151 Eu by Mössbauer effect were obtained to determine the coordination states of Al3+ and Eu3+ ions in these glasses. It was found that the coordination number of Eu3+ ions was 12 and that the average coordination number of A13+ ions was almost 5 in these glasses. By introducing Eu2 O3 , the packing of constituent ions was strongly enhanced and the elastic modulus increased in this system. The compositional dependence of the molar volume and elastic modulus were explained by these states of high coordination number for Eu3+ and low coordination number for Al3+ ions compared with those in the corresponding M2 O3 crystals. 相似文献
932.
933.
Toshio Shimoo Ichiro Tsukada Tadao Seguchi Kiyohito Okamura 《Journal of the American Ceramic Society》1999,82(12):3508-3512
The low-oxygen SiC fiber fabricated by the electron-beam irradiation curing method, Hi-Nicalon, was heated at 1773 to 2273 K in a hot isostatic press (800 MPa of argon) and was subsequently reheated at 1873 K at 1 atm (101 kPa) of argon. The hot isostatic press treatment delayed the onset of fiber deterioration to higher temperature. The fiber strength remained almost unchanged by subsequent reheating at 1873 K in 101 kPa of argon. The thermal stability of Hi-Nicalon, as a consequence of the permanent change in surface structure, can be greatly improved by treating in the hot isostatic press. 相似文献
934.
Mikito Kitayama † Kiyoshi Hirao Motohiro Toriyama Shuzo Kanzaki 《Journal of the American Ceramic Society》1999,82(11):3105-3112
Calculations based on a simple modified Wiener's model for thermal conductivity of a composite material predict that the thermal conductivity of ß-Si3 N4 decreases quickly as the grain-boundary film thickness increases within a range of a few tenths of a nanometer and also that it initially increases steeply with increased grain size, then reaches almost constant values. Because of the faceted nature of the ß-Si3 N4 crystal, the average grain-boundary film thickness is much greater than that in equilibrium. The present study demonstrates both theoretically and experimentally that grain growth alone cannot improve the thermal conductivity of ß-Si3 N4 . 相似文献
935.
Takatoshi Sato Yoshihiro Saito Ichiro Anazawa 《Journal of the American Oil Chemists' Society》1986,63(5):695-698
The decomposition and accompanying changes in surface chemical properties of nonionic surfactants were investigated. The decomposition
of nonionic surfactants occurs in the polyoxyethylene and ester chains. Ester chains were susceptible to decomposition with
an increase in the polyoxyethylene chain length, but polyoxyethylene chains were not. Surface chemical properties such as
solubilizing power, surface tension, effective specific volume, and intrinsic viscosity also deteriorated during decomposition
of the surfactants. 相似文献
936.
Gensuke Okamura Kosuke Ebina Makoto Hirao Ryota Chijimatsu Yasukazu Yonetani Yuki Etani Akira Miyama Kenji Takami Atsushi Goshima Hideki Yoshikawa Takuya Ishimoto Takayoshi Nakano Masayuki Hamada Takashi Kanamoto Ken Nakata 《International journal of molecular sciences》2021,22(1)
Synovial mesenchymal stem cell (SMSC) is the promising cell source of cartilage regeneration but has several issues to overcome such as limited cell proliferation and heterogeneity of cartilage regeneration ability. Previous reports demonstrated that basic fibroblast growth factor (bFGF) can promote proliferation and cartilage differentiation potential of MSCs in vitro, although no reports show its beneficial effect in vivo. The purpose of this study is to investigate the promoting effect of bFGF on cartilage regeneration using human SMSC in vivo. SMSCs were cultured with or without bFGF in a growth medium, and 2 × 105 cells were aggregated to form a synovial pellet. Synovial pellets were implanted into osteochondral defects induced in the femoral trochlea of severe combined immunodeficient mice, and histological evaluation was performed after eight weeks. The presence of implanted SMSCs was confirmed by the observation of human vimentin immunostaining-positive cells. Interestingly, broad lacunae structures and cartilage substrate stained by Safranin-O were observed only in the bFGF (+) group. The bFGF (+) group had significantly higher O’Driscoll scores in the cartilage repair than the bFGF (−) group. The addition of bFGF to SMSC growth culture may be a useful treatment option to promote cartilage regeneration in vivo. 相似文献
937.
Takayuki Morimoto Tsutomu Nakazawa Ryosuke Matsuda Fumihiko Nishimura Mitsutoshi Nakamura Shuichi Yamada Ichiro Nakagawa Young-Soo Park Takahiro Tsujimura Hiroyuki Nakase 《International journal of molecular sciences》2021,22(7)
Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor in adults. Natural Killer (NK) cells are potent cytotoxic effector cells against tumor cells inducing GBM cells; therefore, NK cell based- immunotherapy might be a promising target in GBM. T cell immunoglobulin mucin family member 3 (TIM3), a receptor expressed on NK cells, has been suggested as a marker of dysfunctional NK cells. We established TIM3 knockout in NK cells, using the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9). Electroporating of TIM3 exon 2- or exon 5-targeting guide RNA- Cas9 protein complexes (RNPs) inhibited TIM3 expression on NK cells with varying efficacy. T7 endonuclease I mutation detection assays showed that both RNPs disrupted the intended genome sites. The expression of other checkpoint receptors, i.e., programmed cell death 1 (PD1), Lymphocyte-activation gene 3 (LAG3), T cell immunoreceptor with Ig and ITIM domains (TIGIT), and TACTILE (CD96) were unchanged on the TIM3 knockout NK cells. Real time cell growth assays revealed that TIM3 knockout enhanced NK cell–mediated growth inhibition of GBM cells. These results demonstrated that TIM3 knockout enhanced human NK cell mediated cytotoxicity on GBM cells. Future, CRISPR-Cas9 mediated TIM3 knockout in NK cells may prove to be a promising immunotherapeutic alternative in patient with GBM. 相似文献
938.
We have been studying mesenchymal stem cells (MSCs) in synovial fluid and the intra-articular injection of synovial MSCs in osteoarthritis (OA) knees. Here, mainly based on our own findings, we overview the characteristics of endogenous MSCs in the synovial fluid of OA knees and their mode of action when injected exogenously into OA knees. Many MSCs similar to synovial MSCs were detected in the synovial fluid of human OA knees, and their number correlated with the radiological OA grade. Our suspended synovium culture model demonstrated the release of MSCs from the synovium through a medium into a non-contacting culture dish. In OA knees, endogenous MSCs possibly mobilize in a similar manner from the synovium through the synovial fluid and act protectively. However, the number of mobilized MSCs is limited; therefore, OA progresses in its natural course. Synovial MSC injections inhibited the progression of cartilage degeneration in a rat OA model. Injected synovial MSCs migrated into the synovium, maintained their MSC properties, and increased the gene expressions of TSG-6, PRG-4, and BMP-2. Exogenous synovial MSCs can promote anti-inflammation, lubrication, and cartilage matrix synthesis in OA knees. Based on our findings, we have initiated a human clinical study of synovial MSC injections in OA knees. 相似文献
939.
Eduardo Gomez Ichiro Hisaki Abderrazzak Douhal 《International journal of molecular sciences》2021,22(9)
Hydrogen-bonded organic frameworks (HOFs) are the focus of intense scientific research due their potential applications in science and technology. Here, we report on the synthesis, characterization, and photobehavior of a new HOF (T12F-1(124TCB)) based on a dehydrobenzoannulene derivative containing fluorine atoms (T12F-COOH). This HOF exhibits a 2D porous sheet, which is hexagonally networked via H-bonds between the carboxylic groups, and has an interlayers distance (4.3 Å) that is longer than that of a typical π–π interaction. The presence of the fluorine atoms in the DBA molecular units largely increases the emission quantum yield in DMF (0.33, T12F-COOH) when compared to the parent compound (0.02, T12-COOH). The time-resolved dynamics of T12F-COOH in DMF is governed by the emission from a locally excited state (S1, ~0.4 ns), a charge-transfer state (S1(CT), ~2 ns), and a room temperature emissive triplet state (T1, ~20 ns), in addition to a non-emissive triplet structure with a charge-transfer character (T1(CT), τ = 0.75 µs). We also report on the results using T12F-ester. Interestingly, FLIM experiments on single crystals unravel that the emission lifetimes of the crystalline HOF are almost twice those of the amorphous ones or the solid T12F-ester sample. This shows the relevance of the H-bonds in the photodynamics of the HOF and provides a strong basis for further development and study of HOFs based on DBAs for potential applications in photonics. 相似文献
940.
Ichiro Minami 《Lubrication Science》1995,7(4):319-331
The addition of more antioxidant to aged oils is not always effective in preventing autoxidation. To investigate this phenomenon, a solution of antioxidant and model oxide in hexadecane was examined by means of the induction period method. Aldehydes were found to be the most active species for reducing the antioxidation properties of zinc dialkyldithiophosphate (ZDTP), 2,6-di(tert. butyl)-4-methylphenol (DBPC), and N-phenyl-1-naphtylamine (PNA). Carboxylic acids, ethers, alcohols, and ketones to some extent reduced the induction period with these antioxidants. Esters showed almost no influence on reducing their antioxidant properties. Reaction of ZDTP with aldehyde was studied by means of 31P-NMR analysis. It was found that (a) aldehydes accelerate conversion of ZDTP, and thereby reduce its antioxidant performance. (b) Conversion of ZDTP in the presence of aldehydes under oxygen at 130° in hexadecane and no reaction was observed under nitrogen at the same temperature. Active intermediates derived by the autoxidation of aldehyde were suspected. (c) Reaction of peroxycarboxylic acid with ZDTP took place smoothly at 0°C under nitrogen to give bis(dialkylthiorophosphoro)disulphide and the corresponding carboxylic acid. Reaction of hydroperoxide with ZDTP took place at room temperature to give oxo-hexa(dialkylphosphorothiorothionato)-tetrazinc. Two mechanisms for decomposition of ZDTP promoted by aldehydes, namely hydroperoxide and peroxycarboxylic acid mechanisms, are proposed. Reaction of peroxycarboxylic acid with DBPC or PNA barely took place at room temperature: for these antioxidants, the peroxycarboxylic acid mechanism would be excluded. Radical species derived by the autoxidation of aldehydes were considered as active intermediates. It is considered that classification of the types of oxides that exist in used oils in the key to optimising the effect of re-added antioxidants. 相似文献