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31.
Yuasa J Ohno T Miyata K Tsumatori H Hasegawa Y Kawai T 《Journal of the American Chemical Society》2011,133(25):9892-9902
Highly luminescent tris[β-diketonate (HFA, 1,1,1,5,5,5-hexafluoropentane-2,4-dione)] europium(III) complexes containing a chiral bis(oxazolinyl) pyridine (pybox) ligand--[(Eu(III)(R)-Ph-pybox)(HFA)(3)], [(Eu(III)(R)-i-Pr-pybox)(HFA)(3)], and [(Eu(III)(R)-Me-Ph-pybox)(HFA)(3)])--exhibit strong circularly polarized luminescence (CPL) at the magnetic-dipole ((5)D(0) → (7)F(1)) transition, where the [(Eu(III)(R)-Ph-pybox)(HFA)(3)] complexes show virtually opposite CPL spectra as compared to those with the same chirality of [(Eu(III)(R)-i-Pr-pybox)(HFA)(3)] and [(Eu(III)(R)-Me-Ph-pybox)(HFA)(3)]. Similarly, the [(Tb(III)(R)-Ph-pybox)(HFA)(3)] complexes were found to exhibit CPL signals almost opposite to those of [(Tb(III)(R)-i-Pr-pybox)(HFA)(3)] and [(Tb(III)(R)-Me-Ph-pybox)(HFA)(3)] complexes with the same pybox chirality. Single-crystal X-ray structural analysis revealed ligand-ligand interactions between the pybox ligand and the HFA ligand in each lanthanide(III) complex: π-π stacking interactions in the Eu(III) and Tb(III) complexes with the Ph-pybox ligand, CH/F interactions in those with the i-Pr-pybox ligand, and CH/π interactions in those with the Me-Ph-pybox ligand. The ligand-ligand interactions between the achiral HFA ligands and the chiral pybox results in an asymmetric arrangement of three HFA ligands around the metal center. The metal center geometry varies depending on the types of ligand-ligand interaction. 相似文献
32.
Rahul K. Verma Toshihiko Kuwabara Kwansoo ChungA. Haldar 《International Journal of Plasticity》2011,27(1):82-101
Recently non-proportional deformation has received increased attention from researchers working in the area of experimental and computational modeling of metal deformation. However, most of them are numerical in nature with limited experimental data available, making it further difficult to model non-proportional deformation. In the present work, two-stage uniaxial tests, along with uniaxial cyclic and biaxial tests for different stress ratios, have been performed to evaluate deformation behavior of ultra-low carbon high strength automotive steel. Behaviors like cross-effect and hardening stagnation, which are attributed to the evolution of complex dislocation structures, were observed in this steel. It was also noticed that this steel exhibits tension-compression asymmetry. As for constitutive modeling, a modified asymmetric yield function is proposed to be used with a combined isotropic-kinematic hardening model. Also methods to account for the hardening stagnation during reverse loading and the cross-effect during two-stage deformation are proposed. The resulting constitutive model showed reasonably good agreement with experimental results. 相似文献
33.
The effect of a uniaxial stress on the excitonic optical spectra are studied for MoS2, WS2, MoSe2 and WSe2. Stress dichroism appears in the A′, B′ excitons in diselenides, while it is absent in the A, B excitons in the four compounds. The A′, B′ excitons shift oppositely to the A, B excitons, indicating that A, B and A′, B′ are not pair excitons split by interlayer interaction. 相似文献
34.
35.
Trichlorobiphenyl and tetrachlorobiphenyls in human milk were analysed by gas chromatography--mass spectrometry and mass fragmentography using silicone OV-1 and Apiezon L grease as stationary phases. Low-chlorinated biphenyls had been considered to be excreted rapidly from the body, but in this work quantities of tri- and tetrachlorobiphenyls amounting to approximately 30% of the total of polychlorinated biphenyls (PCBs) accumulated in the milk were identified. This result is important in relation to the quantification of PCBs and in studies of the mechanism of biological degradation. 相似文献
36.
37.
The crystal structure of K2CuF4 has been studied by means of Raman scattering. The structure is found to belong to the space group D4h5 rather than D4h17 of K2NiF4 between 2 and 800 K because of the distortion arising from the “orbital ordering effect”. 相似文献
38.
Feng Dang Kazumi Kato Hiroaki Imai Satoshi Wada Hajime Haneda Makoto Kuwabara 《Ultrasonics sonochemistry》2010,17(2):310-314
A new effect of ultrasonic irradiation on the formation of BaTiO3 particles was identified. Ultrasonication caused the aggregation of the original 5–10 nm BaTiO3 particles in the same crystal axis and accelerated the formation of BaTiO3 particles significantly. Furthermore, narrow size distribution was obtained for the aggregated particles under ultrasonic irradiation. 相似文献
39.
Kishida I Koyama Y Kuwabara A Yamamoto T Oba F Tanaka I 《The journal of physical chemistry. B》2006,110(16):8258-8262
Migration of Li+ ions via the vacancy mechanism in LiX (X = F, Cl, Br, and I) with the rocksalt and hypothetical zinc blende structures and Li2X (X = O, S, Se, and Te) with the antifluorite structure has been investigated using first-principles projector augmented wave calculations with the generalized gradient approximation. The migration paths and energies, determined by the nudged-elastic-band method, are discussed on the basis of two idealized models: the rigid-sphere and charged-sphere models. The trajectories and energy profiles of the migration in these lithium compounds vary between these two models, depending on the anion species and crystal structure. The migration energies in LiX with both the rocksalt and hypothetical zinc blende structures show a tendency to decrease with increasing periodic number of the anion species in the periodic table. This is consistent with the widely accepted view that anion species with large ionic radii and high polarizabilities are favorable for good ionic conduction. In contrast, Li2O exhibits the lowest migration energy among Li2X compounds, although O is the smallest among the chalcogens, indicating that electrostatic attractive interactions play the dominant role in the inter-ion interactions in Li2O and, therefore, in the ion migration. 相似文献
40.
Ultraviolet photolysis of urine for suppression of color quenching prior to liquid scintillation counting of tritium 总被引:1,自引:0,他引:1
In order to reduce the color quenching in the measurement of tritium in urine by liquid scintillation counting , UV irradiation
was applied to decompose the organic substances in the sample. Urine was decolorized under UV irradiation in the presence
of hydrogen peroxide. As a result, color quenching was considerably suppressed and higher counting efficiency of tritium was
obtained. This UV treatment made it possible to increase the urine content in the sample from 2 to 40% (v/v) without significant
decrease of counting efficiency. Either higher sensitivity or shorter analysis time was achieved in the tritium measurement
by the augmentation of urine content. When the measurement time was 30 min, the detection limit of tritium defined as 3s was 0.03 Bq/ml. At the expense of some sensitivity (set at a detection limit of 0.3 Bq/ml), the measurement time was shortened
to 0.5 min. These results will make a great improvement to routine tritium monitoring as well as to emergency monitoring in
mass tritium exposure.
相似文献