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101.
H. Nakatani T. Kita O. Kojima O. Wada K. Akahane M. Tsuchiya 《Journal of luminescence》2008,128(5-6):975-977
We have investigated effects of the strain-compensating spacer layer on photoluminescence (PL) properties of excitons in the multilayered self-assembled quantum dots (SAQDs). The PL decay time of excitons in the sample with a thin spacer layer is longer than that with a thick spacer layer. This is attributed to the lowering of the oscillator strengths owing to reduction of the overlap integral between the electrons and holes envelope functions because of spatially extended electron envelope functions in the growth direction. In addition, the PL intensity of the transverse-magnetic mode in the sample with the thinner spacer layer has been found to be enhanced in the polarized PL measurement from the cleaved edge surface of the samples. These results indicate the possibility of QDs connecting along the growth direction via penetration of the electron envelope function. 相似文献
102.
103.
Keiji Takeda Hiroko Tokoro Fumiyoshi Hakoe Akira Yamaguchi Hatsumi Mori Hidehiko Ishimoto Takayoshi Nakamura Shinya Kuriki Shin-ichi Ohkoshi 《Polyhedron》2009,28(9-10):1746-1749
We have developed a high temperature superconductor (HTS) micro SQUID magnetometer for molecular-based magnets. By employing the dipole approximation, we verified the flux value of 40Φ0 from the saturation magnetic moment of the ferrimagnetic microcrystal of [Mn2(H2O)2(CH3COO)][W(CN)8] · 2H2O (15 × 15 × 13 μm). Considering the relative arrangement of the sample and the SQUID loop, including the influence of the film and grease, the calculated the flux values were Φ = 71Φ0 and 31Φ0 at distances of 20 and 30 μm between the sample bottom face and the SQUID plane, respectively. Thus, the experimentally obtained flux value is reasonable. 相似文献
104.
Masanori Shinohara Hiromichi Shibata Tatsuyuki Nakatani Keishi Okamoto Hiroshi Fujiyama 《Applied Surface Science》2007,253(14):6242-6247
We investigated evolution of hydrocarbon species on a Si surface during methane plasma both with and without substrate bias, using infrared spectroscopy in multiple internal reflection geometry (MIR-IRAS). We found that the relative density of the sp3-CH or sp3-CH2 species to the sp3-CH3 species was low in the low exposure regions, but that the relative density of the sp3-CH or sp3-CH2 species increased as the exposure was higher. Substrate temperatures rose as the plasma exposure was higher. The changes of ratios would be ascribed to the substrate heating effect by plasma exposure, which would enhance the etching and/or hydrogen abstraction effects. We also found the change of CH1-2/CH3 ratios was enhanced when the high substrate bias was applied. The enhancement of the ratio was due to ion effects. 相似文献
105.
Satomi Nakatani Masaaki Sato Hiroshi Hirota Masami Ishibashi 《Tetrahedron letters》2005,46(2):267-271
Melleumin A (1), a novel peptide lactone, has been isolated from the laboratory-cultured plasmodium of myxomycete Physarum melleum, and its structure was elucidated by spectral data. Melleumin A (1) consisted of four residues (p-methoxybenzoic acid, l-threonine, glycine, and an unusual amino acid, a tyrosine-attached acetic acid). 相似文献
106.
Oshio H Nihei M Yoshida A Nojiri H Nakano M Yamaguchi A Karaki Y Ishimoto H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(3):843-848
The reaction of 1/3 equivalent of CuCl2.2H2O with MnCl2.4H2O and 5-bromo-2-salicylideneamino-1-propanol (H(2)5-Br-sap) in methanol gave dark brown crystals of [MnIIICuIICl(5-Br-sap)2(MeOH)] (1). Complex 1 has an alkoxo-bridged dinuclear core of MnIII and CuII ions, which have elongated octahedral and square-planar coordination geometries, respectively. In dc magnetic susceptibility measurements, chi(m)T values increased as the temperature was lowered, followed by a sudden decrease below 20 K. This behavior is indicative of the occurrence of intramolecular ferromagnetic interactions, and fitting gave an S=5/2 spin ground state with an exchange coupling constant J(MnCu) of +78 cm(-1). Magnetization data collected as a function of temperature and applied magnetic field were analyzed by using a spin Hamiltonian with isotropic Zeeman and axial zero-field splitting (ZFS) terms, and a negative D(5/2) value (-1.86 cm(-1)) was obtained. A high-field EPR (HFEPR) spectrum (342.0 GHz) at 4.2 K was composed of four peaks, and two additional peaks at higher magnetic field appeared as the temperature was increased. The temperature dependences in the HFEPR spectra are indicative of a negative D(5/2) value, and fitting of the data gave D(5/2)=-1.81 cm(-1). In the ac magnetic susceptibility measurements, frequency dependent in-phase (chi(m)') and out-of-phase (chi(m)') signals with peak maxima at 0.7-1.5 K were observed and small peaks below 0.7 K appeared. The ac susceptibility data supports that 1 is a single-molecule magnet (SMM). Arrhenius plots for the chi(m)' peaks from 0.7-1.5 K gave the re-orientation energy barrier (DeltaE) of 10.5 K with a pre-exponential factor of 8.2x10(-8) s. 相似文献
107.
In aortic aneurysm tissues, macrophages and their secretion of matrix metalloproteinases (MMPs) are playing important role for tissue degeneration. Some studies have shown that weakening of the mechanical properties of the degenerated tissues may progress the expansion of the aneurysm. However, actual measurement of the mechanical properties has not been investigated at microscopic level. The objective of the present study is to assess the mechanical properties of aortic aneurysm tissues by measuring acoustic properties by scanning acoustic microscopy (SAM). Twenty-one cases of aortic aneurysm including renal and common iliac aneurysm tissues were surgically excised. Each tissue was fixed by 4% formaldehyde and the specimens were treated as (1) picrosirius red staining for normal and polarized light microscopy, (2) CD68 staining for macrophage detection, and (3) no staining for acoustic microscopy. A specially developed SAM system operating in the frequency range of 100-200 MHz, was employed in the measurement. Images of amplitude and phase are obtained in a field of 2x2 mm. The intima was mainly consisted of degenerated collagen without polarization of picrosirius red staining. Macrophages stained by CD68 were observed near the degenerated collagen fibers. The sound speed was 1567 m/s in the intima, 1576 m/s in the media, 1640 m/s in the adventitia, respectively. Infiltration of macrophages showed higher values of attenuation and sound speed than the surrounding tissues. The sound speed of the intima was significantly lower than our previous measurement of atherosclerotic aorta without aneurismal change. As the tissue elasticity is closely correlated with the sound speed, the elasticity of the intima was considered to be lower in aneurysm tissues. This mechanical weakness may contribute to the expansion of the diameter of the aneurysm. Acoustic microscopy provided important data for assessing tissue mechanical properties of abdominal aneurysm. 相似文献
108.
A new configuration is proposed for continuously transforming aspect ratios of field-intensity distributions in optical fibers. The field aspect ratio varies in proportion to the angle between the principal axes of two cascaded graded-index oval-core fibers. The highest aspect-ratio conversion is obtained at an angle of 90 degrees. The conversion effect is numerically and experimentally confirmed, showing that a circular field is successfully transformed into an elliptical one with an aspect ratio as high as 9 at a wavelength of 0.98 microm. 相似文献
109.
110.
Hidehiko Arai Naohiro Hayakawa Naoyuki Tamura Isamu Kuriyama 《Journal of Polymer Science.Polymer Physics》1977,15(10):1697-1706
The fine texture and molecular motion in rolled (draw ratios λ = 2, λ = 5), cold-drawn (λ = 6), and hot-drawn (λ = 6), linear polyethylene (Sholex 6050) films were studied by small-angle x-ray scattering, wide-line nuclear magnetic resonance (NMR), and dynamic viscoelastic measurements. NMR spectra of the rolled (λ = 5) and cold-drawn samples show a small narrow component at room temperature. For these cold-deformed samples, a gradual decrease in the second moment is observed well below the α relaxation temperature and a new relaxation appears in the same temperature region in the logarithmic decrement versus temperature. This relaxation is absent in the original and hot-drawn samples. It is concluded that the new relaxation arises from molecular motion in intermediate regions where molecular chains are less mobile than in the amorphous state. 相似文献