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991.
Junpei T. Okada Takehiko Ishikawa Yuki Watanabe Paul-François Paradis 《The Journal of chemical thermodynamics》2010,42(7):856-859
Surface tension and viscosity of molten vanadium were measured over a wide temperature range by the oscillating drop method in an electrostatic levitation furnace. Over the (2023 to 2517) K temperature range, the surface tension can be expressed as γ(T)/(10?3 N/m) = 1935 ? 0.27 {(T ? Tm)/K} with Tm = 2183 K. Over the same temperature span, the viscosity can be expressed as η(T)/(10?3 Pa · s) = 1.23exp[2.27 · 104/(RTK?1)], where R is the gas constant. 相似文献
992.
Oligophenylene molecular rods with bicyclo[2.2.2]octane having two nitronyl nitroxide radicals were synthesized to investigate the decay constant of p-phenylene. By the measurement and simulation of the ESR spectra of the biradicals with different rod length, it was found that the exchange interaction was decreased with the decay constant β of 0.51 ± 0.01 ?(-1). This result indicates that the spin-spin exchange interaction between neutral radicals has a decay constant similar to the molecular conductance. 相似文献
993.
Markov chain analysis of genetic algorithms applied to?fitness functions perturbed concurrently by additive and multiplicative noise 总被引:2,自引:0,他引:2
Takehiko Nakama 《Computational Optimization and Applications》2012,51(2):601-622
We analyze the transition and convergence properties of genetic algorithms (GAs) applied to fitness functions perturbed concurrently
by additive and multiplicative noise. Both additive noise and multiplicative noise are assumed to take on finitely many values.
We explicitly construct a Markov chain that models the evolution of GAs in this noisy environment and analyze it to investigate
the algorithms. Our analysis shows that this Markov chain is indecomposable; it has only one positive recurrent communication
class. Using this property, we establish a condition that is both necessary and sufficient for GAs to eventually (i.e., as
the number of iterations goes to infinity) find a globally optimal solution with probability 1. Similarly, we identify a condition
that is both necessary and sufficient for the algorithms to eventually with probability 1 fail to find any globally optimal
solution. Our analysis also shows that the chain has a stationary distribution that is also its steady-state distribution.
Based on this property and the transition probabilities of the chain, we compute the exact probability that a GA is guaranteed
to select a globally optimal solution upon completion of each iteration. 相似文献
994.
Ichikawa Y Okumura K Matsuda Y Hasegawa T Nakamura M Fujimoto A Masuda T Nakano K Kotsuki H 《Organic & biomolecular chemistry》2012,10(3):614-622
An efficient synthetic method for stereoselective construction of asymmetric quaternary carbon stereocenters, bearing nitrogen in the form of Boc-protected allyl amines, has been developed. This methodology is employed in the synthesis of marine alkaloids, manzacidin A and C. 相似文献
995.
Sakamoto H Matsuda R Kitagawa S 《Dalton transactions (Cambridge, England : 2003)》2012,41(14):3956-3961
A detailed investigation into the mechanochemical synthesis of coordination pillared-layer frameworks (CPLs), particularly CPL-1, was carried out. In the case of CPL-1, a two-step reaction was observed (from the starting reactants to the final product). In the conventional solution process, no intermediate state was detected. We found that moisture is essential in both the reaction steps. After the final product was washed, it showed the same sorption ability as the product prepared from a solution process. We further demonstrated the systematic preparation of other CPLs (CPL-2, 3, 4, 5, and 15) by the mechanochemical method under humid conditions, even though some of the ligands are almost insoluble in water. Our findings indicate that mechanochemical synthesis is a promising alternative method for the systematic and large-scale production of PCPs. Its advantages include the following: reduced pollution, low cost, simplicity of the process, ease of handling, efficient reaction rate, selectivity, and the issue of low solubility of reactants is overcome. 相似文献
996.
We found that the alignments of the alkali cations can be controlled by a distortion of Prussian blue framework; the rubidium ions form a rod structure in a distorted framework of Rb(0.85)Cu[Fe(CN)(6)](0.95)·1.3H(2)O, while the cesium ions are isolated dot structures in a non-distorted framework of Cs(0.97)Cu[Fe(CN)(6)](0.99)·1.1H(2)O. The Madelung energy calculations revealed that the novel rod structure is stabilized by the alternating rotations of the [Fe(CN)(6)] units within the three-dimensional coordination polymer framework. 相似文献
997.
Hu JY Ni XL Feng X Era M Elsegood MR Teat SJ Yamato T 《Organic & biomolecular chemistry》2012,10(11):2255-2262
Three alkynyl-functionalised, hand-shaped, highly fluorescent and stable emitters, namely, 2-tert-butyl-4,5,7,9,10-pentakis(p-R-phenylethynyl)pyrenes have been successfully synthesized via a Pd/Cu-catalysed Sonogashira cross-coupling reaction. The chemical structures of the alkynylpyrenes were fully characterized by their (1)H/(13)C NMR spectra, mass spectroscopy and elemental analysis. Synchrotron single-crystal X-ray analysis revealed that there is a 1-D, slipped, face-to-face motif with off-set, head-to-tail stacked columns, which are clearly influenced by the single, bulky, tert-butyl group in the pyrene ring at the 2-position. Detailed studies on the photophysical properties in both solutions and thin films strongly indicate that they might be promising candidates for optoelectronic applications, such as organic light-emitting devices (OLEDs) or as models for investigating the fluorescent structure-property relationship of the alkynyl-functionalised pyrene derivatives. 相似文献
998.
Nakajima A Matsuda E Masuda Y Sameshima H Ikenoue T 《Analytical and bioanalytical chemistry》2012,403(7):1961-1970
The characteristics of the spin-trapping reaction in the oxygen radical absorbance capacity (ORAC)-electron spin resonance (ESR) assay were examined, focusing on the kind of spin traps. 2,2-Azobis(2-amidinopropane) dihydrochloride (AAPH) was used as a free radical initiator. The spin adducts of the AAPH-derived free radical were assigned as those of the alkoxyl radical, RO· (R=H(2)N(HN)C-C(CH(3))(2)). Among the spin traps tested, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 5,5-dimethyl-4-phenyl-1-pyrroline N-oxide (4PDMPO), 5-(2,2-dimethyl-1,3-propoxycyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO), and 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO) were applicable to the ORAC-ESR assay. Optimal formation of spin-trapped radical adduct was observed with 1 mM AAPH, 10 mM spin trap, and 5 s UV irradiation. The calibration curve (the Stern-Volmer's plot) for each spin trap showed good linearity, and their slopes, k (SB)/k (ST), were estimated to be 87.7±2.3, 267±15, 228±9, and 213±16 for DMPO, 4PDMPO, CYPMPO, and DEPMPO, respectively. Though the k (SB)/k (ST) values for selected biosubstances varied with various spin traps, their ratios to Trolox (the relative ORAC values) were almost the same for all spin traps tested. The ORAC-ESR assay also had a very good reproducibility. The ORAC-ESR assay was conducted under stoichiometric experimental conditions. The present results demonstrate the superiority of the ORAC-ESR assay. 相似文献
999.
Takeshi Sakano Dr. Jun‐ya Hasegawa Dr. Kenji Higashiguchi Prof. Kenji Matsuda 《化学:亚洲杂志》2012,7(2):394-399
The self‐assembled structure of alkoxy‐ and N‐alkylcarbamoyl‐substituted zinc–tetraphenylporphyrin at the liquid–highly oriented pyrolytic graphite (HOPG) interface was observed by using scanning tunneling microscopy. The alkoxy porphyrin showed a phase transition from face‐on to edge‐on ordering. The phase transition requires the close‐packed structure of alkoxy porphyrin. The chronological change of the ordering was traced to show the existence of several types of Ostwald ripening including two‐step phase transition from small edge‐on to face‐on and then further to edge‐on orderings. On the other hand, the N‐alkylcarbamoyl porphyrin showed persistent edge‐on ordering, and the ordering was analyzed by the Moiré pattern. Although the edge‐on ordering is observed only in the nonpolar solvent, the orderings have potential applications in the charge and energy transfer. 相似文献
1000.
Abe K Fuke H Haino S Hams T Hasegawa M Horikoshi A Kim KC Kusumoto A Lee MH Makida Y Matsuda S Matsukawa Y Mitchell JW Nishimura J Nozaki M Orito R Ormes JF Sakai K Sasaki M Seo ES Shinoda R Streitmatter RE Suzuki J Tanaka K Thakur N Yamagami T Yamamoto A Yoshida T Yoshimura K 《Physical review letters》2012,108(5):051102
The energy spectrum of cosmic-ray antiprotons (p's) from 0.17 to 3.5 GeV has been measured using 7886 p's detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary p calculations. Cosmologically primary p's have been investigated by comparing measured and calculated p spectra. BESS-Polar II data show no evidence of primary p's from the evaporation of primordial black holes. 相似文献