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排序方式: 共有485条查询结果,搜索用时 15 毫秒
1.
Masamura Shinnosuke Iwamoto Tetsu Sugitani Yoshiki Konishi Keiji Hara Naoyuki 《Nonlinear dynamics》2020,99(4):3155-3168
Nonlinear Dynamics - The present study experimentally investigates amplitude death in delay-coupled double-scroll circuits with a time-varying network topology that randomly changes at a regular... 相似文献
2.
Prof. Isao Fujii Dr. Makoto Hashimoto Kaori Konishi Akiko Unezawa Haruka Sakuraba Kenta Suzuki Harue Tsushima Miho Iwasaki Satsuki Yoshida Akane Kudo Rina Fujita Aika Hichiwa Koharu Saito Dr. Takashi Asano Dr. Jun Ishikawa Dr. Daigo Wakana Dr. Yukihiro Goda Ayumi Watanabe Mamoru Watanabe Yui Masumoto Dr. Junichiro Kanazawa Dr. Hajime Sato Prof. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8542-8548
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo-ring formation reactions proceed non-enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo-ring formation and 8π-6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non-enzymatic conversion to shimalactones in the dark. 相似文献
3.
Yoshimichi Shimomura Prof. Dr. Kazunobu Igawa Dr. Shunsuke Sasaki Dr. Noritaka Sakakibara Prof. Dr. Raita Goseki Prof. Dr. Gen-ichi Konishi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(52):e202201884
To design ultrabright fluorescent solid dyes, a crystal engineering strategy that enables monomeric emission by blocking intermolecular electronic interactions is required. We introduced propylene moieties to distyrylbenzene (DSB) as bridges between the phenyl rings either side of its C=C bonds. The bridged DSB derivatives formed compact crystals that emit colors similar to those of the same molecules in dilute solution, with high quantum yields. The introduction of flexible seven-membered rings to the DSB core produced moderate distortion and steric hindrance in the DSB π-plane. However, owing to this strategy, it was possible to control the molecular arrangement with almost no decrease in the crystal density, and intermolecular electronic interactions were suppressed. The bridged DSB crystal structure differs from other DSB derivative structures; thus, bridging affords access to novel crystalline systems. This design strategy has important implications in many fields and is more effective than the conventional photofunctional molecular crystal design strategies. 相似文献
4.
Tae Seok Kwon Sadanori Kumazawa Shuji Kondo† Koji Takagi Hideo Kunisada Yasuo Yuki 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1895-1913
Abstract 1,4-Bis(p-tert-butylphenylselenomethyl) benzene was synthesized, and used as a bifunctional photoiniferter for the polymerization of styrene. Both the polymer yields and the number average of molecular weights (n) of polymers increased with the polymerization. The polymerization of styrene by this iniferter permitted telechelic polystyrene containing arylseleno groups at both chain ends, and the degree of functionality was 1.9. The seleno groups of both chain ends of polystyrene were reduced quantitatively by tri-n-butyltin hydride. These seleno groups in polystyrene were also eliminated by treatment with hydrogen peroxide to give telechelic polystyrene with carbon-carbon double bond at both chain ends. Further, polystyrene with double bonds was converted to telechelic polystyrene carrying terminal functional groups as epoxy, hydroxy, and iodide group, respectively. 相似文献
5.
Yuki Arakawa Hiroki Kuwahara Masatoshi Tokita Gen-ichi Konishi Hideto Tsuji 《Molecular Crystals and Liquid Crystals》2018,662(1):197-207
ABSTRACTWe present a new fabrication approach to achieve a high birefringence film by means of photopolymerization based on an alkylthio-containing rod-like liquid crystalline molecule exhibiting large temperature dependence of birefringence. We designed a new reactive mesogen having alkylthio linkages (BPM–S). It was found that BPM–S had a larger increment of birefringence with decreasing temperature, relative to commercially available alkoxy analog LC242. This result could be thought to be due to enhanced intermolecular attractive interaction for an alkylthio mesogen implied by the proximity of laterally neighboring molecules and cybotactic nematic tendency based on wide-angle X-ray measurement. The uniaxially-aligned photo-polymerized film for BPM–S showed higher birefringence than that for LC 242. 相似文献
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8.
A. A. Ushakov N. Nemoto N. Kanda K. Konishi P. A. Chizhov N. A. Panov D. E. Shipilo V. V. Bukin M. Kuwata-Gonokami J. Yumoto O. G. Kosareva S. V. Garnov A. B. Savel’ev 《JETP Letters》2017,105(11):706-709
A change in the quasistatic magnetic susceptibility in thin plates of iron borate (FeBO3), which is a weak ferromagnet, has been revealed at adsorption of water molecules. The measurements have been performed at room temperature with the use of the magneto-optical Faraday effect. The change of the susceptibility in saturated water vapors is about 30%. The observed effect is reversible. The time of establishing the susceptibility after the introduction of water vapors is 1.5 min, which is twice as large as the time of establishing the susceptibility after the evacuation. The effect is explained by the appearance of uniaxial surface magnetic anisotropy in the basal plane because of the adsorption of water molecules. 相似文献
9.
Makoto Uchimura Ryohei Ishige Masayuki Shigeta Yuki Arakawa Yosuke Niko Junji Watanabe Gen-Ichi Konishi 《Research on Chemical Intermediates》2013,39(1):403-414
We synthesized thermotropic liquid-crystalline polyesters in which 9,10-diphenylanthracene moieties are incorporated into the main chain type of polyester forming the chiral smectic C (Sm C*). The polymers were prepared by the isopropyltitanate-catalyzed reaction of biphenyldicarboxylic acid and the corresponding diols, with different ratios of diol of 9,10-diphenylanthracene moiety to the alkane diols (1, 5, and 10 mol %) under nitrogen atmosphere. The polymers exhibited thermotropic liquid crystals despite the presence of a bulky diphenylanthracene moiety in the main chain. The circular dichroism spectra revealed that a Sm C* phase was formed in the polymer with 1 mol % of anthracene moiety, although only an Sm A phase was formed in the other polymers. This is the first example of a Sm C* polyester containing a diphenylanthracene moiety in the main chain. Furthermore, we measured the optical properties of the polymers and found that they exhibited very high fluorescent efficiency. The fluorescence spectra of the thin film differed from that of a CH2Cl2 solution. 相似文献
10.
An efficient one-pot procedure for the preparation of 4-substituted 4-alkoxy-1,4-dihydro-3,1-benzoxazine-2-thiones from 2-isothiocyanatobenzoates has been developed. Thus, 2-isothiocyanatobenzoates were reacted with organolithiums including lithium enolates of acetates and tertiary acetamides in THF at −78 °C to give the desired products in generally good yields. 相似文献