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971.
We analyzed the acoustic waves propagating in a sphere to establish a useful guideline for the design of NDE apparatus and ball surface acoustic wave (SAW) device exploiting the diffraction-free propagation of SAW on a sphere. First, we calculated the laser-generated acoustic displacements both under ablation condition and under thermoelastic condition and verified experimentally the validity of the calculation. Next, the acoustic waves excited by out-of-plane stress and those excited by in-plane stress were compared. The results showed that when the out-of-plane stress was applied, the relative amplitudes of the bulk waves to that of the SAW were larger and the number of bulk waves was larger than that when the in-plane stress was applied, while the SAW had similar waveforms in each case. The ratio of the relative amplitude of the bulk waves for the out-of-plane stress and the in-plane stress was 3.1:1 at phi(1)=90 degrees and 1.67:1 at phi(1)=0 degrees. The large amplitude for the out-of-plane stress can be explained by wide directivities of bulk waves. Consequently, we found that it is necessary for ball SAW device to select a piezoelectric material and form of interdigital transducer so that the in-plane stress becomes dominant. 相似文献
972.
[reaction: see text] A diastereoisomeric mixture of 1-nitro-6-heptene-2,3,4,5-tetraol derivative (A) was prepared by Henry reaction between d-glucose-based aldehyde and nitromethane. Only the (2S)-isomer of A led to cyclitol (B) via nitronate-olefin cycloaddition on treatment with TMS-Cl and Et(3)N in the presence of catalytic DMAP followed by acid treatment. (+)-Cyclophellitol (1) was synthesized from B in eight steps. 相似文献
973.
Nakano T Ahn DS Ahn JK Akimune H Asano Y Chang WC Daté S Ejiri H Fujimura H Fujiwara M Hicks K Hotta T Imai K Ishikawa T Iwata T Kawai H Kim ZY Kino K Kohri H Kumagai N Makino S Matsumura T Matsuoka N Mibe T Miwa K Miyabe M Miyachi Y Morita M Muramatsu N Niiyama M Nomachi M Ohashi Y Ooba T Ohkuma H Oshuev DS Rangacharyulu C Sakaguchi A Sasaki T Shagin PM Shiino Y Shimizu H Sugaya Y Sumihama M Toyokawa H Wakai A Wang CW Wang SC Yonehara K Yorita T Yoshimura M Yosoi M Zegers RG 《Physical review letters》2003,91(1):012002
The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model. 相似文献
974.
Seto M Kitao S Kobayashi Y Haruki R Yoda Y Mitsui T Ishikawa T 《Physical review letters》2003,91(18):185505
We have performed the measurement of the site-specific phonon densities of states (PDOS) discerned using electronic states. As far as we know, no general method could give the site-specific PDOS, although oscillating properties of the individual atoms in nonequivalent positions are not necessarily equivalent. However, the combination of the energy and time domain measurements of the nuclear resonant scattering of synchrotron radiation allows the identification of site-specific PDOS. We measured the site-specific PDOS of iron atoms in magnetite, which is a mixed valent compound, and the difference between partial phonon densities of the iron sites was clearly observed. 相似文献
975.
S. Kawabata N. Ishikawa M. Mitsui A. Nakajima 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):155-158
Uniform-sized silver nanoparticles with average diameter of 13.7 nm have been prepared in the gas-phase by combining a pulsed
laser ablation method
with a low pressure-differential mobility analyzer (LP-DMA). By depositing
the silver nanoparticles onto a silicon substrate, a granular film
consisting of size-selected silver nanoparticles has been fabricated and its
morphology and electronic properties have been examined using transmission
electron microscopy (TEM) and UV-visible absorption spectroscopy. This
granular silver film serves as a highly active substrate for
surface-enhanced Raman scattering (SERS). 相似文献
976.
Hirohisa Ishikawa 《General Relativity and Gravitation》1983,15(4):305-307
Presented in this paper are exact nonstatic solutions for the coupled repulsive sourceless massless scalar field and the gravitational field. The solutions have the same form as the spatially conformally flat static metricds 2 =e 2ψ dt 2 +e ?2ψ(dx 2 +dy 2 +dz 2). 相似文献
977.
The title reagent, readily prepared from methyl β,β,β-trifluoropropionate with trimethylsilyl triflate, is shown to react with a broad variety of acetals to provide the corresponding α-CF3 β-alkoxy esters in good yields. 相似文献
978.
Nylon-6 α-phase crystal: Chain repeat distance and modulus in the chain direction at low temperature
Keizo Miyasaka Tsuneyuki Isomoto Hiroshi Koganeya Katsuhiko Uehara Kinzo Ishikawa Nobuo Ogata 《Journal of Polymer Science.Polymer Physics》1980,18(5):1047-1052
The chain repeat distance in the α-phase crystal of nylon-6 was measured from ?150 to 150°C. The distance increases with decreasing temperature, indicating that the chain is not a complete planar zigzag but is twisted at room temperature. The relation between the distance and temperature changes at about ?110°C and again near 40°C. Both changes seem to be related to the mechanical dispersions of the material. Young's modulus in the chain direction is 270 GN/m2 at ?150°C, or 14% less than the theoretical value given by Tashiro and Tadokoro for the planar zig-zag structure. It is not possible to determine from the (0k0) diffraction intensities whether the amide or methylene moieties are the more important in the chain twisting. 相似文献
979.
980.
Kaoru Takakura Mitsuo Ishikawa Kotaro Hidea Katsumi Kobayashi Atsushi Ito Takashi Ito 《Photochemistry and photobiology》1986,44(3):397-400
We studied the induction of single-strand breaks in the DNA of plasmid pBR 322 by vacuum-UV radiation above 145 nm in aqueous solutions in relation to the production of OH-radicals in water. The similarity and dissimilarity were examined of the wavelength dependence between the two effects. The maximum of single strand breaks at 150 nm could be explained by the action of OH-radicals derived from direct water photolysis: the maximum at 180 nm remains unexplained. There was no indication that the direct absorption of photon by the DNA molecule plays an important role in the production of single-strand breaks. 相似文献