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171.
Time-dependent pattern entropy is a method that reduces variations to binary symbolic dynamics and considers the pattern of symbols in a sliding temporal window. We use this method to analyze the instability of daily variations in foreign exchange rates, in particular, the dollar–yen rate. The time-dependent pattern entropy of the dollar–yen rate was found to be high in the following periods: before and after the turning points of the yen from strong to weak or from weak to strong, and the period after the Lehman shock. 相似文献
172.
We introduce a notion of (α, β, γ) triple system which generalizes the familiar generalized Jordan triple system. We then discuss its realization by some bilinear algebras and vice versa. We also give a characterization of the structurable algebra of Allison in terms of (?1, 1) Freudenthal–Kantor triple system by imposing some additional triple product constraints. 相似文献
173.
Kentaro Matsumoto Masayoshi Takayanagi Yuichi Suzuki Nobuaki Koga Masataka Nagaoka 《Journal of computational chemistry》2019,40(2):421-429
We have realized the microscopic simulation of olefin polymerization, that is, the simulation of the catalytic polymerization (CP) reaction system composed of (pyridylamido)hafnium(IV) complex as the catalyst. For this purpose, we adopted Red Moon (RM) method, a novel molecular simulation method to simulate the complex reaction system. First, according to the previous research, with the help of the QM calculation, we proposed a model system and elementary processes and explained the theoretical treatment of the simulation by the RM method (the RM simulation). In addition, we also proposed a macroscopic simulation based on chemical kinetics simulation. Then, we performed two simulations and compared them in terms of the effective time evolution of the three macroscopic physical quantities, the number-average molecular weight Mn , the mass-average molecular weight Mw , and the molar-mass dispersity ĐM . The comparison showed that the two simulations are in quantitative or partially qualitative agreement with each other. Therefore, it is concluded that the RM simulation could not only simulate the CP reaction process microscopically, but also it is connected essentially to reproduce the time evolution of the macroscopic physical quantities on the basis of its microscopic simulation data. © 2018 Wiley Periodicals, Inc. 相似文献
174.
A systematic investigation on nanocrystalline LiCoO2 has been carried out using Raman spectroscopy. We synthesized nanocrystalline LiCoO2 (ca. 20-50 nm) through a combination of rapid thermal annealing at various annealing temperatures and a sol-gel method assisted with a triblock copolymer surfactant. Powder X-ray diffraction measurements revealed the formation of LiCoO2. The crystallite size of LiCoO2 from the Scherrer equation strongly depended on the annealing temperature. The crystallite size was confirmed by SEM and TEM measurements. Raman shifts of the A1g and Eg modes for nanocrystalline LiCoO2 exhibited a broadening and a frequency shift according to the crystallite size. While the frequency shift could be ascribed to a structural strain at the surface, the broadening was due to the phonon confinement effect produced by narrow crystal boundaries. 相似文献
175.
176.
Atsushi Sato Shimpei Okubo Kazuhiro Asai Shoken Ishii Kohei Mizutani 《Applied physics. B, Lasers and optics》2014,117(2):621-631
The effect of lower-laser-level lifetimes on Q-switched pulse generation in a dual-wavelength solid-state laser with a common upper laser level was numerically and experimentally investigated. A rate-equation model that accounts for finite lower-laser-level lifetimes was developed, and for a Nd:YAG laser operating at 1064 and 1319 nm, numerical simulations of dual-wavelength pulse generation were performed with and without the effects of lower-laser-level lifetimes. In the laser experiments, characteristics of the dual-wavelength Q-switched pulses agree reasonably well with theoretical predictions. As a result, we found that both the total energy of the two Q-switched pulses and the ratio of 1064–1319-nm pulse energies were strongly affected by the lower-laser-level lifetimes when the Q-switched pulse width was comparable or shorter than the lower-laser-level lifetime. 相似文献
177.
Inside Cover: A Puckered Singlet Cyclopentane‐1,3‐diyl: Detection of the Third Isomer in Homolysis (Chem. Eur. J. 7/2016)
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178.
Mika Sakai Masayoshi Mori Dr. Masato Hirai Dr. Naoki Ando Prof. Dr. Shigehiro Yamaguchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200728
Two kinds of planarized phenyldithienylboranes, which contain (CH3)2C- or CH2-bridging moieties, were synthesized. The difference of the bridging moieties affects their packing structures and photophysical properties. In particular, the (CH3)2C-bridged derivative exhibits a large Stokes shift, unusual for such planarized compounds, that results from a large structural relaxation in the excited state. A series of π-extended derivatives was synthesized, among which a p-(diphenylamino)phenyl-substituted derivative shows large solvatochromism in the fluorescence spectra, while maintaining high quantum yields even in polar solvents. The Lewis acidity of the phenyldithienylborane derivatives was also assessed by titration with pyridine. The Lewis acidity of the boron center is affected not only by the difference in the steric bulk of the bridging moieties, but also by the electronic effect of the substituents introduced at remote positions relative to the boron atom. These results demonstrate the characteristic features of planarized phenyldithienylboranes as building blocks for boron-based π-electron materials. 相似文献
179.
Enantioselective Construction of Silicon‐Stereogenic Silanes by Scandium‐Catalyzed Intermolecular Alkene Hydrosilylation
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Dr. Gu Zhan Dr. Huai‐Long Teng Dr. Yong Luo Dr. Shao‐Jie Lou Dr. Masayoshi Nishiura Prof. Dr. Zhaomin Hou 《Angewandte Chemie (International ed. in English)》2018,57(38):12342-12346
The catalytic asymmetric construction of silicon‐stereogenic silanes is of great interest and significance, but has met with only limited success to date. We herein report the enantioselective hydrosilylation of alkenes with dihydrosilanes by a chiral half‐sandwich scandium catalyst, which constitutes an efficient and general route for the synthesis of a wide range of enantioenriched silicon‐stereogenic silanes from easily accessible starting materials. This reaction features a broad substrate scope, high yields, and high enantioselectivity. Some of the chiral tertiary silane products were also converted into valuable derivatives, such as chiral silanol, quaternary silane, and benzosilole compounds. 相似文献
180.
Directing Aluminum Atoms into Energetically Favorable Tetrahedral Sites in a Zeolite Framework by Using Organic Structure‐Directing Agents
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Koki Muraoka Prof. Watcharop Chaikittisilp Yutaka Yanaba Prof. Takeshi Yoshikawa Prof. Tatsuya Okubo 《Angewandte Chemie (International ed. in English)》2018,57(14):3742-3746
The Al location in zeolites can have massive influences on the zeolite properties because it directly correlates with the cationic active sites. Herein, the synthesis of IFR zeolites with controlled Al distribution at different tetrahedral sites (T sites) is reported. The computational calculations suggest that organic structure‐directing agents (OSDAs) used for zeolite synthesis can alter the energetically favorable T sites for Al. Zeolite products synthesized under identical conditions but with different OSDAs are found to have altered fractions of Al at different T sites in accordance with the energies derived from the zeolite–OSDA complexes. Our finding thus provides evidence for the ability of OSDAs to direct Al into more energetically favorable T sites, thereby offering rational synthetic guidelines for the selective placement of Al into specific crystallographic sites. 相似文献