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21.
Kazuaki Nakamura Reiko Mizutani Atsushi Sanbe Shin Enosawa Mureo Kasahara Atsuko Nakagawa Yoko Ejiri Norie Murayama Yuki Miyamoto Tomohiro Torii Shinji Kusakawa Junji Yamauchi Motohiro Fukuda Hiroshi Yamazaki Akito Tanoue 《Journal of Bioscience and Bioengineering》2011,111(1):78-84
A micro-space cell culture system was recently developed in which cells such as hepatocytes can be cultured and formed into a multicellular three-dimensional (3D) architecture. In this study, we assessed the performance of HepG2 cells cultured in this micro-space cell culture system in a drug toxicity test, and evaluated the effects of micro-space culture on their hepatocyte-specific functions. The micro-space cell culture facilitated the formation of 3D HepG2 cell architecture. HepG2 cells cultured in a micro-space culture plate exhibited increased albumin secretion and enhanced mRNA expression levels of cytochrome P450 (CYP) enzyme compared to those cultured in a monolayer culture. When the cells were exposed to acetaminophen, a hepatotoxic drug, the damage to the HepG2 cells grown in micro-space culture was greater than the damage to the HepG2 cells grown in monolayer culture. In addition, human primary hepatocytes grown in micro-space culture also exhibited increased albumin secretion, enhanced CYP mRNA expression levels and increased sensitivity to acetaminophen compared to those grown in monolayer culture. These results suggest that this micro-space culture method enhances the hepatocyte-specific functions of hepatocytes, including drug-metabolizing enzyme activities, making hepatocytes grown in the micro-space culture system a useful tool for evaluating drug toxicity in vitro. 相似文献
22.
Hiroyasu Kido Sridhar Komarneni Rustum Roy 《Journal of the American Ceramic Society》1991,74(2):422-424
The La2 Zr2 O7 phase was prepared from metal acetylacetonates by a sol—gel route without any intermediate phase formation. X-ray peaks appeared at a temperature as low as 500°C at the positions expected for La2 Zr2 O7 , although they were broad. The crystal structure of La2 Zr2 O7 was found to be of the fluorite type below 900°C and of thepyrochlore type above 1000°C. The substitution of a small amount of Eu for La was carried out to investigate the crystal structure from the viewpoint of fluorescence, and these results confirmed the formation of fluorite type La2 Zr2 O7 below 900°C. 相似文献
23.
When predators invade a leaf patch inhabited by herbivores, the herbivores disperse to a neighboring predator-free leaf patch,
thus escaping from the predators. However, the neighboring patch might already be used by con- or heterospecific herbivores.
We used laboratory bioassays to examine whether perception of odor from con- or heterospecific competitors on a neighbored
lima bean leaf patch influences dispersal behavior of the herbivorous mite Tetranychus urticae when attacked by predatory mites Phytoseiulus persimilis. The dispersal rates of T. urticae that perceived odors from leaf patches infested by conspecifics or cowpea aphids (Aphis craccivora) did not differ from the control (the dispersal rate of T. urticae that perceived odor from uninfested leaf patches). By contrast, the dispersal rate of T. urticae was reduced when they perceived odors from leaf patches that were currently or had previously been infested by larvae of
the common cutworm (Spodoptera litura). Previous herbivory by S. litura larvae induced resistance in leaf patches to T. urticae as indicated by the reduced number of eggs laid by T. urticae. Our results are discussed with respect to the feeding behavior of the tested competitors of T. urticae and the impact of the plant and arthropod community on the dispersal behavior of these mites. 相似文献
24.
Koichi Awazu Xiamin Wang Junji Tominaga Hirohiko Aiba Tetsuro Komatsubara 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(6):941-943
It has been reported that elongated Au nanoparticles oriented parallel to one another can be synthesized in SiO2 by ion irradiation. Our aim was to elucidate the mechanism of this elongation. We prepared Au and Ag nanoparticles with a diameter of 20 nm in an SiO2 matrix. It was found that Au nanoparticles showed greater elongated with a higher flux of ion beam and with thicker SiO2 films. In contrast, Ag nanoparticles split into two or more shorter nanorods aligned end to end in the direction parallel to the ion beam. These experimental results are discussed in the framework of a thermal spike model of Au and Ag nanorods embedded in SiO2. The lattice temperature exceeds the melting temperatures of SiO2, Au and Ag for 100 ns after one 110 MeV Br10+ ion has passed through the middle of an Au or Ag nanorod. 相似文献
25.
Molecular, seasonal, and spatial distributions of organic aerosols from fourteen Chinese cities 总被引:7,自引:0,他引:7
Organic aerosols were studied at the molecular level in 14 coastal and inland mega-cities in China during winter and summer 2003. They are characterized by the abundant presence of n-alkanes (annual average, 340 ng m(-3)), fatty acids (769 ng m(-3)), sugars (412 ng m(-3)), and phthalates (387 ng m(-3)). In contrast, fatty alcohols, polyols/polyacids, lignin and resin products, sterols, polycyclic aromatic hydrocarbons (PAHs), and hopanes were detected as relatively minor components. n-Alkanes show a weak odd/even carbon predominance (CPI = 1.1) and PAHs show a predominance of benzo(b)fluoranthene, suggesting a serious contribution from fossil fuel (mainly coal) combustion. Their concentrations (except for phthalates and polyols/polyacids) were 2-15 times higher in winter than summer due to a significant usage of coal burning and an enhancement of atmospheric inversion layers. Phthalates were found to be more abundant in summer than winter, probably due to enhanced vaporization from plastics followed by adsorptive deposition on the pre-existing particles. Concentrations of total quantified compounds are extremely high (approximately 10 microg m(-3)) in the midwest (Chongqing and Xi'an) where active industrialization/urbanization is going on. This study shows that concentrations of the compounds detected are 1-3 orders of magnitude higher than those reported from developed countries. 相似文献
26.
27.
采用正交试验法完成了HSS/Co-M35含钴高速钢丝锥加工Ti-6Al-4V钛合金的攻丝试验。利用极差分析法研究了丝锥全生命周期参数即丝锥前角(刀具设计参数)、刃口钝化半径(刀具制造参数)、主轴转速(刀具使用参数)对攻丝性能的影响。利用综合评分法将扭矩max、轴向切削力max和切削温度max等3项攻丝性能指标转化为单一综合切削性能指标y*i,分析结果表明:攻钛合金时丝锥全生命周期参数取刃口钝化半径0.01 mm,丝锥前角10°,主轴转速150 r/min时最优。通过试验与数值模拟获得的扭矩值及趋势、切屑形态及切削刃对比图,验证了在Advant Edge FEM软件中建立的丝锥攻Ti-6Al-4V钛合金模型的可靠性。 相似文献
28.
Toshiyuki Abe Junji KubotaTamotsu Tanaka Kuniaki ShojiAkio Tajiri Masao Kaneko 《Electrochimica acta》2002,47(24):3901-3907
Electrocatalytic O2 reduction was studied using a modified electrode coated with a Nafion membrane (Nf) dispersing a trinuclear ruthenium ammine complex ([(NH3)5RuIIIORuIV(NH3)4ORuIII(NH3)5]Cl6, Ru-red). When measuring cyclic voltammogram under O2 atmosphere (at 0.5 mV s−1), catalytic currents due to O2 reduction were found to develop below −0.2 V (vs. Ag/AgCl). Since Ru-red undergoes irreversible decomposition into the mononuclear complexes via the reduced state (RuIII-RuIII-RuIII) (∼−0.1 V), it is suggested that the electrocatalysis originates from the decomposed species (initial active species: RuII(NH3)5(OH2) and RuII(NH3)4(OH2)2) rather than from the Ru-red. Although the present electrocatalyst was also applied to H2O2 reduction system, the catalytic activity was found to be poor from the voltammetric behavior. It appeared that the kinetics of the electrocatalysis is much faster in the O2 reduction than in the H2O2 one. A selective and direct catalysis for O2 reduction into H2O was suggested from a ring-disk voltammogram to take place by an aggregate of the mononuclear ruthenium complexes in the polymer matrix. In addition, it was found that electrocatalytic O2 reduction involves a slow kinetic process, so that factors affecting the overall kinetics were discussed in terms of the catalysis mechanism. 相似文献
29.
加压下液体过热的亚稳态 总被引:2,自引:0,他引:2
本文用液滴悬浮法测定了十四种碳氢化合物的加压情况下的过热极限,并经筛选由mvdW方程对过热极限进行了预测,发现两者符合较好。 相似文献
30.
Yingqing Zhan Fanbin Meng Xulin Yang Junji Wei Jian Yang Yanke Zou Heng Guo Rui Zhao Xiaobo Liu 《应用聚合物科学杂志》2013,127(3):1827-1833
Poly(arylene ether nitrile) (PEN) nanocomposites filled with functionalized graphite nanoplates (GNs) were prepared by a simple solution‐ casting method and then characterized by rheometer and thermogravimetric analysis (TGA). This study investigates how the surface treatment of GNs affects the GN dispersion state. The linear rheological test indicated that the 4‐aminophenoxyphthalonitrile‐grafted GN (GN‐CN) presented better dispersion in PEN matrix than purified GN because the corresponding composite showed the lower rheological percolation threshold, which was further confirmed by scanning electron microscopy and solution experiments. The TGA revealed that the presence of 4‐aminophenoxyphthalonitrile‐grafted GN retarded the depolymerization evidently compared with that of purified GN, showing remarkable increase in the temperatures corresponding to a weight loss of 5 wt % (increased by 21°C) and maximum rate of decomposition (increased by 9°C). Both the dispersion state and the surface functionalization of GN are very important to the thermal stability of PEN matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献