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101.
We have successfully synthesized novel polyurethanes where PU1 contains a [3]rotaxane that consists of N-3,5-di-tert-butylbenzyl-N-3-hydroxypropylammonium hexafluorophosphate (AOH1) and N,N′-Dimethyl-N,N′-bis(dibenzo-24-crown-8)-terephthalamide (BisC) as well as PU2 contains a [2]rotaxane that consists of AOH1 and dibenzo-24-crown-8 ether. Diphenylmethanediisocyanate (MDI), 1,4-butanediol (BD) and poly(ε-caprolactone)diol (PCL) were used as an isocyanate, chain expander, and soft segment, respectively. A polyurethane without any rotaxane structures (PU0) were also prepared as a reference polymer. The existence of the rotaxanes in the polyurethanes was confirmed by 1H NMR spectroscopy and TGA measurement. ATR-FT-IR spectral measurement revealed that the rotaxanes disturb the formation of hydrogen bonding between the polyurethane chains. From the DSC result, the rotaxanes retard the recrystallization of the PCL unit whereas no influence on the glass transition temperatures of the polyurethanes was observed. The retarding effect appeared remarkably with PU1. These thermal behaviors of the polyurethanes were also supported by viscoelastic measurement. In tensile test, the tensile strength and break of strain of PU1 were larger than those of PU2. 相似文献
102.
Docosahexaenoic acid (DHA) supply to the fetal brain depends upon the dam’s dietary intake of n-3 fats. In this study, we
measured the incorporation of DHA into the fetal brain and liver in n-3 fatty acid deficient (0.1% alpha-linolenate) mice
upon switching to an n-3 fatty acid adequate (2.1% alpha-linolenate) diet. Second generation mice raised and maintained on
an n-3 deficient diet during mating were switched to an n-3 adequate diet on embryonic day 1 (ED 1) or ED 13. Fatty acid analysis
was performed on fetal brains and livers and on maternal serum on ED 13, 15, 17, and 19. Although fetal brain and liver DHA
began at a very low level (both exhibited an 85% decline), recovery was nearly complete by ED 15 in the group switched near
conception but thereafter diverged. The maternal serum and fetal liver were very similar in their DHA and docosapentaenoic
acid time courses. However, when repletion began on ED 13, brain DHA recovery was only about 44%. These results suggest that
a nutritional intervention with alpha-linolenic acid can nearly but incompletely rescue the mouse fetal DHA deficiency if
began at the time of conception but that the third trimester is too late, thus leaving a large DHA gap. 相似文献
103.
Akiko Nakahashi Eisuke Miyoshi Kensuke Naka Yoshiki Chujo 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(1):55-66
Radical reaction of bis(4-prop-2-ynyloxyphenyl) disulfide (1) with 2,2′-azobis(isobutyronitrile) as an initiator provided a polymer with dithioalkene units (2). The 1H and 13C NMR spectra of 2 showed that 2 had mainly E-form dithioalkene structure. The radical reactions of 1 and diphenyl diselenide (3) or diphenyl ditelluride (5) were also carried out. At higher temperature than 70 °C, polymers were obtained with less amount of AIBN than in the case
of the homopolymerization of 1. Addition of 3 or 5 in the reaction mixture appeared to promote the radical reaction. Moreover, the obtained structure has high contents of thio-seleno
alkene or thio-telluro alkene than expected, which is due to difference of the chalcogen radical reactivity and difference
of capture ability of the dichalcogenide.
相似文献
Yoshiki Chujo (Corresponding author)Email: |
104.
Haruki Ejiri Akiko Kumada Kunihiko Hidaka Taiki Donen Kentaro Kokura 《Electrical Engineering in Japan》2019,206(1):32-41
Breakdown voltages of vacuum gaps become lower when the gaps are contaminated by metallic and ceramic microparticles. In this paper, the motion of the microparticles in the gap is simulated using Monte Carlo method in order to evaluate the effect of parameters upon motion and the removal time of the microparticles. As the parameters, we focused on the material of the microparticle, the frequency, the peak value of the applied voltage, the gap length, and the diameter of the lower and upper electrodes. It turned out that the maximum time needed to remove all microparticles could be expressed as multiple regression function. It is suggested that the reliability of the microparticle removal can be increased by spark conditioning with opening/closing operation. 相似文献
105.
Akiko Hamada Makoto Kobayashi Katsushi Matsuoka Masato Suzuki Junya Osuo Naoko Ashikawa Akio Sagara Yuji Hatano Yasuhisa Oya Kenji Okuno 《Fusion Engineering and Design》2012,87(7-8):1214-1217
The behavior of hydrogen retention and the change of chemical states of boron film exposed to hydrogen plasma in LHD were investigated. The sample was prepared in LHD, and atomic concentrations for the boron film after hydrogen plasma exposure were changed from 75% for boron, 15% for carbon and 8% for oxygen to 53%, 18% and 22%, respectively. BC bond was a major chemical state of the boron film after hydrogen plasma exposure, although abundance of BB bond was the highest before the plasma exposure. Total hydrogen retention measured by TDS was evaluated to be 1.7 × 1020 H m?2, and the retentions of hydrogen as BHB, BH and BCH bonds were, respectively, 4.8 × 1019, 7.2 × 1019 and 5.2 × 1019 H m?2. It was concluded that the hydrogen retention could be estimated by taking account not only of chemical states of impurities, but also of hydrogen depth profile. 相似文献
106.
为了提高PEMFC的阳极催化剂活性,降低Pt载量,分别采用甲醛、甲酸钠、连二亚硫酸钠、水合肼4种还原剂通过化学还原沉积法制备Pt/C催化剂;向溶液中加入某种羧酸盐(RCOOM)作为吸附剂,制备Pt/C催化剂;利用粉末微电极的循环伏安研究和恒电位极化研究考核了上述催化剂对H_2阳极氧化的催化活性的影响;通过XRD和TEM技术对催化剂的结构及微观形貌进行了分析。结果表明,甲醛作为还原剂得到的铂催化剂在碳载体上分布均匀,粒径较小,催化性能最好;加入适量吸附剂则使Pt颗粒的平均粒径减小到3.4nm,催化剂性能有明显改善。 相似文献
107.
Tomoyuki Kanehira Akiko Takahashi Jun Imai Shigeyuki Funabiki 《Electrical Engineering in Japan》2015,193(4):49-57
Renewable forms of energy such as solar energy have attracted attention as alternative sources of fossil fuel. The output power of photovoltaic generation systems changes steeply. Changes in output power have an effect on the electric power quality of the power system. For that reason, a system which can smooth fluctuations of output power is required. In this paper, the moving average, modified moving average, single exponential smoothing, and double exponential smoothing methods are applied to electric power smoothing control schemes for distributed generation systems with photovoltaic generation. The reduction rate of power fluctuations and the maximum stored energy of electric double layer capacitors are adopted as system evaluation measures. To confirm the effectiveness of the power smoothing control methods, a distributed generation power system with photovoltaic generation systems is simulated with the power electronics circuit simulation software PSIM. The methods are then compared by evaluating the reduction in the capacity of electric double layer capacitors without loss in the power smoothing effect. 相似文献
108.
Akiko Nagai Yuko Yamazaki Chufan Ma Kosuke Nozaki Takeshi Toyama Kimihiro Yamashita 《Journal of the European Ceramic Society》2012,32(11):2647-2652
Micro-arc oxidation (MAO) is one of the useful surface modifications of titanium implants to improve bioactivity. Also, electric polarization treatment enhances bioactivity of calcium phosphate. The aim of this study was to evaluate the effect of the combination of two surface modifications, micro-arc oxidation (MAO) with electric polarization, on the behavior of osteoblast-like osteosarcoma MG63 cells. MAO-treated materials had a surface geometry that was favored by MG63 cells as determined using scanning electron microscopy and X-ray diffraction; additionally, electric polarization induced surface electric fields, which were measured using thermally stimulated depolarization currents. The results of assays to study cell–material interactions suggest that these two approaches could regulate cell attachment, spreading, proliferation, and differentiation without the addition of other reagents. This new surface modification processes produce materials with a good surface geometry, generate surface electric fields and enhance the osteopromotive ability of osteoblasts. 相似文献
109.
Tharnath Nanthirudjanar Hidehiro Furumoto Jiawen Zheng Young‐Il Kim Tsuyoshi Goto Nobuyuki Takahashi Teruo Kawada Si‐Bum Park Akiko Hirata Nahoko Kitamura Shigenobu Kishino Jun Ogawa Takashi Hirata Tatsuya Sugawara 《Lipids》2015,50(11):1093-1102
Hydroxy and oxo fatty acids were recently found to be produced as intermediates during gut microbial fatty acid metabolism. Lactobacillus plantarum produces these fatty acids from unsaturated fatty acids such as linoleic acid. In this study, we investigated the effects of these gut microbial fatty acid metabolites on the lipogenesis in liver cells. We screened their effect on sterol regulatory element binding protein‐1c (SREBP‐1c) expression in HepG2 cells treated with a synthetic liver X receptor α (LXRα) agonist (T0901317). The results showed that 10‐hydroxy‐12(Z)‐octadecenoic acid (18:1) (HYA), 10‐hydroxy‐6(Z),12(Z)‐octadecadienoic acid (18:2) (γHYA), 10‐oxo‐12(Z)‐18:1 (KetoA), and 10‐oxo‐6(Z),12(Z)‐18:2 (γKetoA) significantly decreased SREBP‐1c mRNA expression induced by T0901317. These fatty acids also downregulated the mRNA expression of lipogenic genes by suppressing LXRα activity and inhibiting SREBP‐1 maturation. Oral administration of KetoA, which effectively reduced triacylglycerol accumulation and acetyl‐CoA carboxylase 2 (ACC2) expression in HepG2 cells, for 2 weeks significantly decreased Srebp‐1c, Scd‐1, and Acc2 expression in the liver of mice fed a high‐sucrose diet. Our findings suggest that the hypolipidemic effect of the fatty acid metabolites produced by L. plantarum can be exploited in the treatment of cardiovascular diseases or dyslipidemia. 相似文献
110.
Parallel Post‐Polyketide Synthase Modification Mechanism Involved in FD‐891 Biosynthesis in Streptomyces graminofaciens A‐8890 下载免费PDF全文
Prof. Dr. Fumitaka Kudo Koichi Kawamura Takashi Furuya Hiroto Yamanishi Atsushi Motegi Akiko Komatsubara Mario Numakura Prof. Dr. Akimasa Miyanaga Prof. Dr. Tadashi Eguchi 《Chembiochem : a European journal of chemical biology》2016,17(3):233-238
To isolate a key polyketide biosynthetic intermediate for the 16‐membered macrolide FD‐891 ( 1 ), we inactivated two biosynthetic genes coding for post‐polyketide synthase (PKS) modification enzymes: a methyltransferase (GfsG) and a cytochrome P450 (GfsF). Consequently, FD‐892 ( 2 ), which lacks the epoxide moiety at C8–C9, the hydroxy group at C10, and the O‐methyl group at O‐25 of FD‐891, was isolated from the gfsF/gfsG double‐knockout mutant. In addition, 25‐O‐methyl‐FD‐892 ( 3 ) and 25‐O‐demethyl‐FD‐891 ( 4 ) were isolated from the gfsF and gfsG mutants, respectively. We also confirmed that GfsG efficiently catalyzes the methylation of 2 and 4 in vitro. Further, GfsF catalyzed the epoxidation of the double bond at C8‐C9 of 2 and 3 and subsequent hydroxylation at C10, to afford 4 and 1 , respectively. These results suggest that a parallel post‐PKS modification mechanism is involved in FD‐891 biosynthesis. 相似文献