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排序方式: 共有273条查询结果,搜索用时 31 毫秒
71.
72.
Atsushi Kuwabara Mayu Enomoto Eiji Hosono Kazuma Hamaguchi Taira Onuma Satoshi Kajiyama Takashi Kato 《Chemical science》2020,11(39):10631
Nanostructured, uncharged liquid-crystalline (LC) electrolyte molecules having bicyclohexyl and cyclic carbonate moieties have been developed for application in Li-ion batteries as quasi-solid electrolytes, which suppress leakage and combustion. Towards the development of safe and high performance Li-ion batteries, we have designed Li-ion conductive LC materials with high oxidation resistance using density functional theory (DFT) calculation. The DFT calculation suggests that a mesogen with a bicyclohexyl moiety is suitable for the high-oxidation-resistance LC electrolytes compared to a mesogen containing phenylene moieties. A tri(oxyethylene) chain introduced between the cyclic carbonate and the bicyclohexyl moiety in the core part tunes the viscosity and the miscibility with Li salts. The designed Li-ion conductive LC molecules exhibit smectic LC phases over a wide temperature range, and they are miscible with added lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt up to 5 : 5 in molar ratio in their smectic phases. The resulting LC mixtures with LiTFSI show oxidation resistance above 4.0 V vs. Li/Li+ in cyclic voltammetry measurements. The enhanced oxidation resistance improves the performance of Li half-cells containing LC electrolytes.Ion-conductive liquid-crystalline molecules with high-oxidation resistance, which were designed with density functional theory calculation, improved charge–discharge reactions in Li-ion batteries. 相似文献
73.
We investigated the in vitro superoxide anion scavenging activities of fluvastatin and its metabolites. Fluvastatin showed dose-dependent superoxide anion scavenging activity in the NADH/phenazine methosulphate (PMS)/nitroblue tetrazolium (NBT) system, and the effect was as potent as the reference antioxidant, trolox, which is a water-soluble alpha-tocopherol derivative. The superoxide anion scavenging activities of the major metabolites of fluvastatin (M2, M3, M4, M7) were also determined in this system. All of these metabolites showed the activity. In particular, M2 and M3, which possess a phenolic hydroxyl group at the 5 or 6-position of the indole moiety, respectively, showed 3 times stronger activities than that of fluvastatin. Further, we also determined the effects of fluvastatin, M2 and M3 on phorbol myristate acetate (PMA)-induced superoxide anion generation in human peripheral blood polymorphonuclear leukocytes (PMN). The compounds tested also showed a depressing effect on the amount of superoxide anion in this system. We suggest that fluvastatin and its metabolites have the potential to protect cells or lipids from oxidative modification mediated by superoxide anion. 相似文献
74.
A detection and fixation method of single and multiple gold nanoparticles on the wall of a microfluidic channel is demonstrated. A thermal lens microscope (TLM) with continuous-wave excitation (wavelength, 532 nm) and probe (wavelength, 670 nm) laser beams was used to realize the sensitive detection of heat generated by light absorption of individual gold nanoparticles (50 nm in diameter); fixation of the individual nanoparticles was realized simultaneously. The fixation mechanism was investigated and attributed to an absorption-based optical force. In addition to single nanoparticle detection, multiple-nanoparticle detection and fixation was demonstrated. An acceleration of fixation was observed when the number of fixed particles was increased. TLM is expected to be a powerful tool for both the quantitative detection and precise fixation of individual nanoparticles. 相似文献
75.
Strain-induced nanopatterns formed by the coadsorption of nitrogen and oxygen atoms are studied on the Cu(0 0 1) surface by scanning tunneling microscopy. A square grid pattern similar to that on the N-adsorbed surface appears, and consists of square c(2 × 2) areas with adsorbed N and O atoms when the total density of the adsorbates is around 30% of the Cu atom density on the clean surface. We evaluated the surface strain using a first-principles calculation for a coadsorbed surface and compared it with those on the clean and N-adsorbed surfaces. The strain on the coadsorbed surface is smaller than that of the N-adsorbed surface. The observed size of the square c(2 × 2) area on the coadsorbed surface is larger than that on the N-adsorbed surface with increasing the density of the adsorbates on average as expected by the strain reduction. On the other hand, there is no significant difference in the period of the grid pattern. 相似文献
76.
77.
A Combined Experimental and Computational Study on the Cycloisomerization of 2‐Ethynylbiaryls Catalyzed by Dicationic Arene Ruthenium Complexes 下载免费PDF全文
Prof. Dr. Yoshihiko Yamamoto Kazuma Matsui Dr. Masatoshi Shibuya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7245-7255
Ruthenium‐catalyzed cycloisomerization of 2‐ethynylbiaryls was investigated to identify an optimal ruthenium catalyst system. A combination of [η6‐(p‐cymene)RuCl2(PR3)] and two equivalents of AgPF6 effectively converted 2‐ethynylbiphenyls into phenanthrenes in chlorobenzene at 120 °C over 20 h. Moreover, 2‐ethynylheterobiaryls were found to be favorable substrates for this ruthenium catalysis, thus achieving the cycloisomerization of previously unused heterocyclic substrates. Moreover, several control experiments and DFT calculations of model complexes were performed to propose a plausible reaction mechanism. 相似文献
78.
Yue-Wei Ge Shu Zhu Kohei Kazuma Sheng-Li Wei Kayo Yoshimatsu Katsuko Komatsu 《Analytical and bioanalytical chemistry》2016,408(13):3555-3570
79.
80.
Takumi Nakamura Kazuma Ban Dr. Yasushi Yoshida Prof. Dr. Takashi Mino Prof. Dr. Yoshio Kasashima Prof. Dr. Masami Sakamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(66):16338-16341
Asymmetric synthesis was performed by combining the photochemical reaction of an achiral substrate followed by crystallization-induced deracemization. The results indicated that a fused indoline produced by photochemical intramolecular δ-hydrogen abstraction and cyclization of N-(5-chloro-2-methylphenyl)phthalimide crystallized as a racemic conglomerate. Since this substrate has an aminal skeleton, racemization involving a ring-opening and ring-closing equilibrium process occurred under suitable conditions. Efficient racemization was observed in acetone containing a catalytic base, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Crystallization-induced dynamic deracemization by Viedma ripening from racemic indoline was performed with an excellent enantioselectivity of 99 % ee. Furthermore, one-pot asymmetric synthesis of the indoline was achieved by the photochemical reaction of achiral phthalimide followed by continuous attrition-enhanced deracemization converging to 99 % ee of enantiomeric crystals. This is the first example of asymmetric expression and amplification by photochemical hydrogen abstraction and crystallization-induced dynamic deracemization. 相似文献