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81.
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
82.
We propose an improvement of the replica-exchange and replica-permutation methods, which we call the replica sub-permutation method (RSPM). Instead of considering all permutations, this method uses a new algorithm referred to as sub-permutation to perform parameter transition. The RSPM succeeds in reducing the number of combinations between replicas and parameters without the loss of sampling efficiency. For comparison, we applied the replica sub-permutation, replica-permutation, and replica-exchange methods to a β-hairpin mini protein, chignolin, in explicit water. We calculated the transition ratio and number of tunneling events in the parameter space, the number of folding–unfolding events, the autocorrelation function, and the autocorrelation time as measures of sampling efficiency. The results indicate that among the three methods, the proposed RSPM is the most efficient in both parameter and conformational spaces. © 2019 Wiley Periodicals, Inc. 相似文献
83.
84.
Secondary batteries such as Li‐ion battery are expected to be utilized as not only ubiquitous electric power sources such as mobile phones but also large‐scale electricity storage devices. Therefore, it is urgent to develop the higher performance secondary batteries. Their lifetime and stability are found to be strongly dependent on the nature of passivation film called solid electrolyte interphase (SEI) film formed on the anode surface in the initial charge‐discharge cycle. However, since it is difficult to directly observe the film formation processes in experiment, its microscopic mechanism is still not found. On the other hand, although the theoretical methods are useful complement to the experiment, some new methodologies are necessary to understand the long‐term processes of SEI film, which is produced as a result of that a lot of chemical reactions proceed simultaneously. Under the circumstances, we have developed Red Moon method that can simulate such complex chemical reaction systems, and were able to analyze for the first time the SEI film formation processes on the anode surface at the atomistic level. Then, we clarified theoretically the microscopic mechanism of the additive effect which is essential to improve the Na‐ion battery performance so as to enhance the SEI film formation. This new microscopic insight must provide an important guiding principle for use in designing the most suitable electrolytes for developing high‐performance secondary batteries. 相似文献
85.
Masataka Hakamada Motohiro Yuasa Takashi Yoshida Fumi Hirashima Mamoru Mabuchi 《Applied Physics A: Materials Science & Processing》2014,114(4):1061-1066
ZnO deposited on nanoporous Au showed photocatalytic decomposition toward methyl orange under visible light, unlike ZnO sputtered on flat Au without a nanoporous structure. First-principles calculations suggested that the surface lattice disorder in nanoporous Au induced a band gap narrowing and a large built-in electric field in the adjacent ZnO, resulting in the visible-light photocatalytic response. 相似文献
86.
Investigation of Mizoroki‐Heck coupling polymerization as a catalyst‐transfer condensation polymerization for synthesis of poly(p‐phenylenevinylene)
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Masataka Nojima Ryosuke Saito Yoshihiro Ohta Tsutomu Yokozawa 《Journal of polymer science. Part A, Polymer chemistry》2015,53(4):543-551
Mizoroki‐Heck coupling polymerization of 1,4‐bis[(2‐ethylhexyl)oxy]‐2‐iodo‐5‐vinylbenzene ( 1 ) and its bromo counterpart 2 with a Pd initiator for the synthesis of poly(phenylenevinylene) (PPV) was investigated to see whether the polymerization proceeds in a chain‐growth polymerization manner. The polymerization of 1 with tBu3PPd(Tolyl)Br ( 10 ) proceeded even at room temperature when 5.5 equiv of Cy2NMe (Cy = cyclohexyl) was used as a base, but the molecular weight distribution of PPV was broad. The polymerization of 2 hardly proceeded at room temperature under the same conditions. In the polymerization of 1 , PPV with H at one end and I at the other was formed until the middle stage, and the polymer end groups were converted into tolyl and H in the final stage. The number‐average molecular weight (Mn) did not increase until about 90% monomer conversion and then sharply increased after that, indicating conventional step‐growth polymerization. The occurrence of step‐growth polymerization, not catalyst‐transfer chain‐growth polymerization, may be interpreted in terms of low coordination ability of H‐Pd(II)‐X(tBu3P) (X = Br or I), formed in the catalytic cycle of the Mizoroki‐Heck coupling reaction, to π‐electrons of the PPV backbone; reductive elimination of H‐X from this Pd species with base would take place after diffusion into the reaction mixture. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 543–551 相似文献
87.
Dr. Toshiro Takao Dr. Yuta Takahashi Masataka Kai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(29):e202200327
A dicationic triruthenium complex containing a μ3-η3-C3 ring, [(Cp*Ru)3(μ3-η3-C3MeH2−)(μ3-CH)(μ-H)]2+ ( 1 a , Cp*=η5-C5Me5), reacted with ammonia to yield a μ-amido complex, [(Cp*Ru)3(μ3-η3-CHCMeCH) (μ3-CH)(μ-NH2)]2+ ( 5 ), via N−H bond scission. Subsequent treatment with base resulted in C−N bond formation to yield a μ3-η2:η2-1-azabutadien-4-yl complex, [(Cp*Ru)3(μ3-CH)(μ3-η2:η2-NH=CH−CMe=CH−)]+ ( 6 a ). The azaruthenacyclopentadiene skeleton was alternatively synthesized by the photolysis of mono-cationic complex [(Cp*Ru)3(μ3-η3-C3RH2−)(μ3-CH)]+ ( 2 a ; R=Me, 2 b ; R=H) in the presence of ammonia. The C3 ring skeleton was broken via the electron transfer to the π*(C−C) orbital in the C3 ring, and a transiently generated unsaturated μ3-allylic species can take up ammonia, resulting in N−H bond scission followed by C−N bond formation. 相似文献
88.
Masataka Hoshino 《Journal of Crystal Growth》1991,110(4):704-712
The decomposition mechanisms of trimethylarsine (TMAs) with triethylgallium (TEGa) were studied using a sampling gas method with a mass spectrometer. When TEGa is present, the TMAs concentration starts to decrease at temperatures about 100°C lower than for TMAs alone. The TMAs concentration in the gas phase decreases simultaneously with TEGa decomposition. The rate constant of the TMAs concentration decrease is strongly affected by the TMAs/TEGa mole ratio. However, the TEGa decomposition rate is not affected by the TMAs/TEGa mole ratio. The TMAs concentration decrease is mostly due to the decomposition of the adduct between TMAs and TEGa. TMAs in the gas phase starts to decompose and generate methane at 400°C. However, some TMAs molecules probably adsorb on the reactor surface and/or are incorporated into the GaAs crystal as carbon. Between 340 and 450°C, the concentration of carbon in the TMAs adsorbed on the surface as TMAs and/or incorporated into GaAs as carbon atom is stable and keeps a constant concentration: the TMAs generates no methane. 相似文献
89.
Structural inhomogeneities of μc-Si:H in the range 20≈500 A are observed for the first time by small angle X-ray scattering. Inhomogeneous distributions of bonded hydrogen in the amorphous tissue are suggested to be a possible origin of the SAXS yield. Such inhomogeneities can be reduced when the average grain size and volume fraction of microcrystallites are simultaneously increased. 相似文献
90.
A novel ethyl 5-cyano-6-hydroxy-2-methyl-4-(1-naphthyl)-nicotinate is successfully synthesized and the structure is determined by XRD, GC-MS analysis, element analysis and NMR spectroscopic in detail. A reaction mechanism for the reaction is proposed. 相似文献