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排序方式: 共有429条查询结果,搜索用时 46 毫秒
421.
Ikeyama Masami Masuda HaruhoMiyajima Tatsuya Choi Junho 《Surface & coatings technology》2011,206(5):999-1002
Diamond-like carbon (DLC) films have been attractive materials because of their excellent mechanical properties such as high hardness, low friction coefficient, high wear resistance and more. In order to spread the application of the DLC coatings for polymer materials, it is necessary to make the temperature go down during the coating process.Our group has been studying DLC coatings on several materials with bipolar pulse type PBII (plasma based ion implantation) systems, which consist of positive and negative (or bipolar) pulse generators and a timing controller. Recently we have introduced a new bipolar pulse generator, whose slew-rate is several times larger than that of previous generators, and a controller which can make a very short pulse less than 1 μs. Using the pulse generator and controller, we have tried to make Si incorporated DLC (Si-DLC) coatings on fluoro rubber, which is widely used in many industries, at low temperature.Using the new pulse generator and controller, we can make very short width positive pulse of about 1 μs, and reduce the temperature during Si-DLC coating to about 30 K. The lower temperature makes fewer folds on the sample surface. By using optical indentation microscope system, Meyer hardness (HM) of uncoated and Si-DLC coated fluoro rubber was obtained and the value of HM for Si-DLC coated rubber is about 1.4 times larger than that of uncoated rubber. Coefficient of friction of Si-DLC coated rubber was 0.2 to 0.25 and drastically decreased from 1.3 to 1.9 of uncoated rubber. Wear of uncoated fluoro rubber is apparent, however, wear of Si-DLC coated rubber cannot be observed, except for the creep effect of fluoro rubber substrate. The counter SUJ2 ball surfaces also showed almost no wear. Si-DLC coating can make the tribological property of fluoro rubber to low friction and less wear. Si-DLC coatings are very useful in many applications. 相似文献
422.
Yuya Kido Reika Sakai Baiju John Masami Okamoto Jukka V. Sepp?l? 《International journal of molecular sciences》2014,15(6):9793-9808
To understand the enzymatic degradation behavior of crosslinked polylactide (PLA), the preparation and enzymatic degradation of both thermoplastic (linear) and crosslinked PLAs that have pore structures with different dimensions were carried out. The porous structures of the linear PLA samples were of micro and nanoporous nature, and prepared by batch foaming with supercritical CO2 and compared with the porous structures of crosslinked PLA (Lait-X) created by the salt leaching method. The surface and cross-sectional morphologies of the porous structures were investigated by using scanning electron microscopy. The morphological analysis of porous Lait-X showed a rapid loss of physical features within 120 h of exposure to proteinase-K enzymatic degradation at 37 °C. Due to the higher affinity for water, enhanced enzymatic activity as compared to the linear PLA porous structures in the micro and nanoporous range was observed. 相似文献
423.
Motoyasu Kobayashi Masami Terada Yuki Terayama Moriya Kikuchi Atsushi Takahara 《Israel journal of chemistry》2012,52(3-4):364-374
Surface-initiated atom transfer radical polymerization (ATRP) of (2-methacryloyloxyethyl)trimethylammonium chloride (MTAC), 3-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatopropanesulfonate) (MAPS), and 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out in 2,2,2-trifluoroethanol (TFE) containing a small amount of 1-hexyl-3-methylimidazolium chloride at 60 °C to produce well-defined ionic polymer brushes and the corresponding free polymers with predictable number-average molecular weight (Mn, 1×104−3×105 g mol−1) and narrow molecular weight dispersity (Mw/Mn<1.2). A first-order kinetic plot for ATRP of MTAC and MAPS revealed a linear relationship between the monomer conversion index (ln([M]0/[M])) and polymerization time. Reduction in polymerization rates was observed with an increase in ionic liquid concentration. The Mn of both poly(MTAC) and poly(MAPS) increased in proportion to the conversion. The sequential polymerization of MAPS initiated with the chain ends of poly(MAPS) produced the postpolymer with quantitative efficiency. The thickness of the polymer brush was controllable from 5 to 100 nm based on the Mn of the polymer. These results suggest the successful control of the polymerization of sulfobetaine-type methacrylates owing to the TFE and ionic liquids. In particular, the high affinity of TFE for the sulfobetaine monomers and polymers yielded a homogeneous polymerization media to improve surface-initiated polymerization generating the polymer brushes on the substrate surface as well as the free polymers formed in the solution. The effect on ATRP of the chemical structure of ionic liquids and ligands for copper catalyst was also investigated. 相似文献
424.
Goto K Hashimoto M Takadama H Tamura J Fujibayashi S Kawanabe K Kokubo T Nakamura T 《Journal of materials science. Materials in medicine》2008,19(3):1009-1016
In this study, polymethylmethacrylate-based composite cements containing 40–55.6 wt% micron-sized titania (titanium oxide)
particles were developed, and their mechanical, setting, and biological properties evaluated. Three types of composite cement
containing 40, 50, and 55.6 wt% silanized titania were designated ST2-40c, ST2-50c, and ST2-56c, respectively. In animal experiments,
ST2-50c and ST2-56c were implanted into rat tibiae and solidified in situ. An affinity index was used to evaluate osteoconductivity.
Compressive and bending strength of ST2-56c was 147.7 ± 3.2 and 69.3 ± 7.4; those of the other cements exceeded 100 MPa and
50 MPa, respectively. The affinity indices of ST2-56c were 42.1 ± 12.9 at six weeks and 53.4 ± 16.6 at 12 weeks, and were
significantly higher than for ST2-50c and a commercial PMMA bone cement within 12 weeks. Our data indicate that bone cement
containing micron-sized titania particles can be applied to prosthesis fixation as well as vertebroplasty, and ST2-56c is
a good candidate cement. 相似文献
425.
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427.
Tsugumasa Toma Hiroshi Tateishi Kensaku Kawakami Taha F. S. Ali Masahiro Kamo Kazuaki Monde Yuta Nakashima Mikako Fujita Masami Otsuka 《International journal of molecular sciences》2022,23(9)
Cancer metastasis accounts for most of the mortality associated with solid tumors. However, antimetastatic drugs are not available on the market. One of the important biological events leading to metastasis is the epithelial to mesenchymal transition (EMT) induced by cytokines, namely transforming growth-factor-β (TGF-β). Although several classes of inhibitors targeting TGF-β and its receptor have been developed, they have shown profound clinical side effects. We focused on our synthetic compound, HPH-15, which has shown anti-fibrotic activity via the blockade of the TGF-β Smad-dependent signaling. In this study, 10 μM of HPH-15 was found to exhibit anti-cell migration and anti-EMT activities in non-small-cell lung cancer (NSCLC) cells. Although higher concentrations are required, the anti-EMT activity of HPH-15 has also been observed in 3D-cultured NSCLC cells. A mechanistic study showed that HPH-15 inhibits downstream TGF-β signaling. This downstream inhibition blocks the expression of cytokines such as TGF-β, leading to the next cycle of Smad-dependent and -independent signaling. HPH-15 has AMPK-activation activity, but a relationship between AMPK activation and anti-EMT/cell migration was not observed. Taken together, HPH-15 may lead to the development of antimetastatic drugs with a new mechanism of action. 相似文献
428.
Junya Miyahara Naoki Shirakawa Yuta Setoguchi Masami Tsubota Kento Kuroiwa Jiro Kitagawa 《Journal of Superconductivity and Novel Magnetism》2018,31(11):3559-3564
The Hill plot is a well-known criterion of the f-electron element interatomic threshold distance separating the nonmagnetic state from the magnetic state in actinides and lanthanides. We have reinvestigated the Hill plot of Ce compounds using the commercial crystallographic database CRYSTMET, focusing on a relationship between the Ce-Ce distance and the magnetic ordering temperature because a Ce compound with no other magnetic elements rarely has a magnetic ordering temperature that is higher than 20 K. The Hill plot of approximately 730 compounds has revealed that a Ce compound, particularly a ferromagnet, showing a high magnetic ordering temperature would require a short Ce-Ce distance with a suppression of the valence instability of the Ce ion. From the study, we developed interest in Ce2AuP3 with a Curie temperature of 31 K. The ferromagnetic nature of this material has been examined in terms of a doping effect, which suggests a possible increase in magnetic anisotropy energy. 相似文献
429.
Hongjia Zhu Masako Narita Jerelle A. Joseph Georg Krainer William E. Arter Ioana Olan Kadi L. Saar Niklas Ermann Jorge R. Espinosa Yi Shen Masami Ando Kuri Runzhang Qi Timothy J. Welsh Rosana Collepardo-Guevara Masashi Narita Tuomas P. J. Knowles 《Chembiochem : a European journal of chemical biology》2023,24(1):e202200450