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71.
Wei Sun Xiaojie Li Kazuyuki Hokamoto 《Applied Physics A: Materials Science & Processing》2014,117(4):1941-1946
We show direct evidence that underwater shock wave enables us to bond multithin plates with flat, parallel, and high-strength interfaces, which are key requirements for functionally graded material (also called graded density impactor). This phenomenon is ascribed to the super short duration of the high-speed underwater shock wave, reducing the surface tension, diffusion, evaporation, deposition, and viscous flow of matter. Thin magnesium, aluminum, titanium, copper, and molybdenum foils were welded together and designed with the increase in density. Experimental evidence and numerical simulation show that well bonding between the multilayer structures. Microstructure examinations reveal that the dominant interfacial form shifts from waviness to linearity. Graded density impactor with multilayer structure is proved that can produce quasi-isentropic compression in two-stage gas gun experiment with a designed pressure loading profile, which suggests a feasible method to simulate the conditions we want to study that were previously inaccessible in a precisely controlled laboratory environment. 相似文献
72.
Prof. Joe Otsuki Takumi Okumura Dr. Kosuke Sugawa Dr. Shin-ichiro Kawano Prof. Kentaro Tanaka Dr. Takehiro Hirao Prof. Takeharu Haino Yu Jin Lee Seongsoo Kang Prof. Dongho Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):4053-4063
Self-assembly of porphyrins is a fascinating topic, not only for mimicking chlorophyll assemblies in photosynthetic organisms, but also for the potential of creating molecular-level devices. Herein, zinc porphyrin derivatives bearing a meta-pyridyl group at the meso position were prepared and their assemblies studied in chloroform. Among the porphyrins studied, one with a carbamoylpyridyl moiety gave a distinct 1H NMR spectrum in CDCl3, which allowed the supramolecular structure in solution to be probed in detail. Ring-current-induced chemical-shift changes in the 1H NMR spectrum, together with vapor-pressure osmometry and diffusion-ordered NMR spectroscopy, among other evidence, suggested that the porphyrin molecules form a trimer with a triangular cone structure. Incorporation of a directly linked porphyrin–ferrocene dyad with the same assembling properties in the assemblies led to a rare example of a light-harvesting/charge-separation system in which an energy gradient is incorporated and reductive quenching occurs. 相似文献
73.
Kazuyuki Kubo Hiroshi Nakazawa Hiroyasu Inagaki Tomoyuki Miyake Tsutomu Mizuta Katsuhiko Miyoshi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8-9):2159-2160
Treatment of [Cp*(CO) 2 M{P(NHPh)(OMe) 2 }]PF 6 (M = Fe and Ru) with NaNH 2 gives metallaiminophosphoranes, Cp*(CO) 2 M{P(NPh)(OMe) 2 }. The x-ray structures and reactivity of the complexes are reported. 相似文献
74.
Shigeru Oae Kazuyuki Iida Toshikazu Takata 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):103-113
Abstract Reduction of sulfimides and sulfoximides with p-toluenesulfonyl nitrite, a new nitrosating agent, gave nearly quantitatively the corresponding deimination products, sulfides and sulfoxides, respectively. In the reaction of dialkyl and aryl alkyl sulfoximides with t-butyl thionitrate, N-t-butylthiosulfoximides were obtained besides the usual deimination products, although diaryl sulfoximides were readily deiminated to the corresponding sulfoxides in good yields in the same treatment. t-Butyl thionitrate was also found to deiminate diphenyl sulfimide to give diphenyl sulfide in good yield. Sulfoximides reacted sluggishly with t-butyl thionitrite, however, eventually affording a small amount of sulfoxides. 相似文献
75.
S. Nakahama M. Kobayashi T. Ishizone A. Hirao M. Kobayashi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1845-1855
Abstract N,N-Dimethyl-, diethyl-, and dipropylacrylamides were polymerized with 1,1-bis(4′-trimethylsilylphenyl)-3-methylpentyllithium (I) in the presence and absence of diethylzinc in THF. Although the polymers produced with I in the absence of diethylzinc have rather broad molecular weight distributions, the addition of diethylzinc to the polymerization systems causes narrow molecular weight distributions of the polymers. The addition of diethylzinc also affect the stereospecificities of the polymers obtained. The poly(N,N-diethylacrylamide) produced with I/diethylzinc (molar ratio of 1/3-15) is highly syndiotactic, while the one obtained with I is isotactic. The configuration of the poly(N,N-dimethylacrylamide) is changed from isotactic to syndio and heterotactic rich by the addition of diethylzinc to the polymerization mixture. Little effect of diethylzinc is observed on the stereospecificity of the polymerization of N,N-dipropylacrylamide. The stoichiometric additive effect of Et2Zn toward the initiator in the polymerization of DEAA suggests that the coordination of Et2Zn aggregates with the propagating carbanionic species narrows the molecular weight distribution and controls the tacticity of the polymer. 相似文献
76.
The acceleration effect of poly(ethylene oxide) on nucleophilic reactions was investigated. The enhancement of the reaction rate was interpreted by the cooperative solvation of alkali metal ions with ethereal oxygens of PEO resulting in active nucleophilic anions. In relation to the complex formation of alkali metal ions with PEO, the oligo(ethylene oxide) derivatives were prepared as the synthetic ionophores, which were able to transport alkali metal ions selectively through a liquid membrane against the alkali metal ion concentration. 相似文献
77.
78.
Syntheses of cyclic oligomer and polymer were attempted with magnesiacyclohexane as the initiator in HMPA. The oligomer of α-methylstyrene, initiated by magnesiacyclohexane, was treated with dimethyldichlorosilane in order to obtain a stable cyclic oligomer. The products were investigated by GPC, IR, NMR, and elemental analysis. It was found that magnesia-cyclohexane could not be activated enough by HMPA, and that the magnesium-carbon bond was not stable in HMPA, and that the chain transfer reaction might occur repeatedly during the polymerization. Consequently, the yield of cyclic oligomer was so low that cyclic compounds could not be discriminated from the linear oligomer. 相似文献
79.
Abstract With a 1:1 and a 2:1 host-guest stoichiometry, α-cyclodextrin (α-CD) forms inclusion complexes with 2-chloronaphthalene. From simulations concerning observed chemical-shift differences (Δδobs) of proton signals of 2-chloronaphthalene, intrinsic Δδ values are estimated for all the guest protons in the 1:1 and 2:1 inclusion complexes. The intrinsic Δδ values indicate that α-CD first binds to a part of a naphthalene ring bearing a C1 atom to form the 1:1 inclusion complex. In the 1:1 and 2:1 inclusion complexes, the symmetry axes of α-CD are tilted approximately 30° relative to a naphthalene longitudinal axis. In the 2:1 inclusion complex, the association through hydrogen bonding most likely occurs between two α-CD molecules whose symmetry axes are laterally shifted. 相似文献
80.
Kenichiro Todoroki Hiroki Hashimoto Kazuyuki Machida Miki Itoyama Tadashi Hayama Hideyuki Yoshida Hitoshi Nohta Manabu Nakashima Masatoshi Yamaguchi 《Journal of separation science》2013,36(2):232-238
In this study, we combined a column‐switching system with a fluorous scavenging derivatization method to develop a fully automated reagent peak‐free LC fluorescence detection protocol for the analysis of highly polar carboxylic acids. In this method, highly polar carboxylic acids were derivatized with fluorescent 1‐pyrenemethylamine in the presence of 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide and 1‐hydroxy‐1H‐benzotriazole. Residual excess of the unreacted reagent was tagged with 2‐(perfluorooctyl)ethyl isocyanate and then removed selectively using a fluorous column‐switching system placed in front of an analytical reversed‐phase column. The signal of the fluorous‐tagged unreacted reagent was completely absent in the resulting chromatograms; therefore, it did not interfere with the quantification of each acid especially those eluted before 20 min. The detection limits (S/N = 3) for the examined acids were in the range from 4.0 to 22 fmol per injection. We have applied this method to comparative analysis of highly polar carboxylic acids in urine samples obtained from diabetes mellitus type‐II model mice and their control. 相似文献