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91.
Hierarchical porous γ-alumina is successfully fabricated from a precursor solution consisting of surfactants, polystyrene
(PS) spheres, inorganic salts and solvents. After calcinations, uniform macropores are closely packed. The macropore size
coincides with the original PS sphere size. These macropores are connected by small windows. In addition, the macropore walls
have mesoporous structures, as confirmed by SAXS measurement and TEM observation. After calcination at 900 °C, the amorphous
alumina frameworks are converted to the crystallized γ-alumina phase. Even after crystallization, the existence of uniform
mesopores and high surface are well retained, though the mesoporous ordering is lower. 相似文献
92.
The free induction decay (FID) of the polycrystalline sample of the phenoxyl radical derived from α-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-tert-butylnitrone, which is a novel spin-trapping reagent, in a corresponding diamagnetic matrix was successfully observed after
one pulse even at room temperature, while FIDs of phenoxyl radicals usually are inaccessible due to their short relaxation
times and the dead time of the pulse EPR spectrometer. This may be the first experimental observation in phenoxyl-type radicals.
This study thus showed the unique character of the phenoxyl radical, that is, the distribution of the electron density relative
to the usefulness for the spin-trapping techniques.
Authors' address: Toshiki Yamaji, Materials Characterization Division, National Metrology Institute, National Institute of
Advanced Industrial Science and Technology, Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan 相似文献
93.
Gang Wei Nozomu Sasage Yusuke Kusanagi Kazuhiro Fujiki Takeshi Yamauchi Norio Tsubokawa 《Journal of polymer science. Part A, Polymer chemistry》2008,46(12):4218-4226
The surface grafting of hyperbranched cyclotriphosphazene polymer onto silica nanoparticles and carbon black was investigated. The grafting of hyperbranched cyclotriphosphazene polymer onto these surfaces was achieved by the repeated reactions of hexachlorocyclotriphosphazene with hexamethylenediamine from surface amino groups and sodium carboxylate groups, respectively. The percentage of grafting onto silica and carbon black surfaces exceeded 760 and 390%, respectively. However, it proved difficult to achieve the theoretical growth of cyclotriphosphazene polymer from these surfaces because of steric hindrance. The introduction of sulfonic acid groups was successfully achieved by the reaction of terminal chlorophosphazene groups of the hyperbranched polymer‐grafted silica and carbon black with sulfanilic acid. The content of sulfonic acid groups introduced onto silica and carbon black surfaces was 4.98 mmol/g and 5.70 mmol/g, respectively. The sulfonated cyclotriphosphazene polymer‐grafted carbon black was extremely hydrophilic, yielding stable colloidal dispersions in polar solvents. The sulfonated cyclotriphosphazene polymer‐grafted silica and carbon black showed ionic conductivity, with the conductance increasing exponentially with increasing relative humidity and temperature. This study may offer important leads in the application of silica nanoparticles and carbon black in polymeric membranes for fuel cells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4218–4226, 2008 相似文献
94.
The power spectrum analysis using the Lomb-Scargle false alarm probability statistic shows a clear separation between the average and fluctuating parts of the state density in embedded two-body random matrix ensembles with a mean-field for both fermion and boson systems as well as in the nuclear shell model. 相似文献
95.
Noriki Kutsumura Kota Shibuya Hitoshi Yamaguchi Takao Saito 《Tetrahedron letters》2017,58(43):4099-4102
Regioselective elimination of a vicinal bis-triflate having an adjacent ether oxygen functional group has been developed. Considered in the context of our studies of the regioselective elimination of vicinal dibromide, the key to the mechanism involves the electron-withdrawing inductive effect of the neighboring oxygen functional group. Aliphatic vinyl triflate was shown to be effective in Suzuki–Miyaura cross coupling compared with corresponding aliphatic vinyl bromide. 相似文献
96.
Mannepalli Lakshmi Kantam Gopaladasu Tirupati Venkanna Kota Balaji Shiva Kumar Vura Bala Subrahmanyam 《Helvetica chimica acta》2010,93(5):974-979
N‐Arylation of N‐containing heterocycles, such as pyrazoles, imidazoles, and benzimidazoles with aryl‐, heteroaryl‐, and vinylboronic acids was efficiently carried out by copper fluorapatite (CuFAP) catalyst in MeOH at room temperature under base‐free conditions. The N‐arylated heterocycles were isolated in good‐to‐excellent yields. 相似文献
97.
Osuga T Murase T Ono K Yamauchi Y Fujita M 《Journal of the American Chemical Society》2010,132(44):15553-15555
Three-dimensional m × n arrays of metal ion clusters can be assembled as aromatic stacks of planar polynuclear metal complexes within columnar coordination cages. The polynuclear complexes and cage height program the final array structures of the metal ion clusters. Cyclic trinuclear Au(I) complexes (m = 3) assembled into trigonal prismatic arrays (n = 1-3) within the cages and the array structures were clearly shown by X-ray crystallographic analysis. A silver-sandwiched hetero-Au(3)-Ag-Au(3) cluster was also prepared by treating a hexanuclear Au(3)-Au(3) cluster with Ag(I) ion. 相似文献
98.
Reaction of the benzene-linked bis(pyrazolyl)methane ligands, 1,4-bis{bis(pyrazolyl)-methyl}benzene (L1) and 1,4-bis{bis(3-methylpyrazolyl)methyl}benzene (L2), with pentamethylcyclopentadienyl rhodium and iridium complexes [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rh and Ir) in the presence of NH4PF6 results under stoichiometric control in both, mono and dinuclear complexes, [(η5-C5Me5)RhCl(L)]+ {L = L1 (1); L2 (2)}, [(η5-C5Me5)IrCl(L)]+ {L = L1 (3); L2 (4)} and [{(η5-C5Me5)RhCl}2(μ-L)]2+ {L = L1 (5); L2 (6)}, [{(η5-C5Me5)IrCl}2(μ-L)]2+ {L = L1 (7); L2 (8)}. In contrast, reaction of arene ruthenium complexes [(η6arene)Ru(μ-Cl)Cl]2 (arene = C6H6, p-iPrC6H4Me and C6Me6) with the same ligands (L1 or L2) gives only the dinuclear complexes [{(η6-C6H6)RuCl}2(μ-L)]2+ {L = L1 (9); L2 (10)}, [{(η6-p-iPrC6H4Me)RuCl}2(μ-L)]2+ {L = L1 (11); L2 (12)} and [{(η6-C6Me6)RuCl}2(μ-L)]2+ {L = L1 (13); L2 (14)}. All complexes were isolated as their hexafluorophosphate salts. The single-crystal X-ray crystal structure analyses of [7](PF6)2, [9](PF6)2 and [11](PF6)2 reveal a typical piano-stool geometry around the metal centers with six-membered metallo-cycle in which the 1,4-bis{bis(pyrazolyl)-methyl}benzene acts as a bis-bidentate chelating ligand. 相似文献
99.
S. Vasala Y.H. Huang H. Yamauchi M. Karppinen 《Journal of solid state chemistry》2010,183(5):1007-1012
We have investigated a series of double-perovskite oxides Sr2MMoO6−δ (M=Mg, Mn, Fe, Co, Ni, Zn) for redox stability, oxygen content and crystal structure. Phases with M=Co, Ni and Zn were found to be oxygen-stoichiometric and stable under oxidizing conditions, whereas those with M=Mn and Fe were oxygen-deficient and stable under reducing conditions. The M=Mg phase is stable both under reducing and oxidizing conditions, showing variable oxygen contents within 0.00≤δ≤0.04 depending on the annealing conditions. Structural data indicate somewhat depressed values for the degree of M/Mo cation order and also evidence of electron transfer from MII to MoVI for M=Mn, Fe and Co. 相似文献
100.
Yamauchi Y Sekiguchi K Chida K Arakawa T Nakamura S Kobayashi K Ono T Fujii T Sakano R 《Physical review letters》2011,106(17):176601
We measure the current and shot noise in a quantum dot in the Kondo regime to address the nonequilibrium properties of the Kondo effect. By systematically tuning the temperature and gate voltages to define the level positions in the quantum dot, we observe an enhancement of the shot noise as temperature decreases below the Kondo temperature, which indicates that the two-particle scattering process grows as the Kondo state evolves. Below the Kondo temperature, the Fano factor defined at finite temperature is found to exceed the expected value of unity from the noninteracting model, reaching 1.8±0.2. 相似文献