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621.
Shin‐Ichi Hirota Yoichi Tominaga Shigeo Asai Masao Sumita 《Journal of Polymer Science.Polymer Physics》2005,43(21):2951-2962
An in situ dielectric measurement for atactic poly(methyl methacrylate) (at‐PMMA) was performed under high‐pressure CO2 under various pressures and temperatures. The at‐PMMA has the acetate side group with a large dipole moment. In the glassy state, a local relaxation process (β‐process) can be observed using dielectric measurement. In the rubbery state, the micro‐Brownian motion of main chain (α‐process) occurs, and the β‐process changes into αβ‐process coordinated with the α‐process. The dielectric loss (ε″) spectrum of at‐PMMA in the glassy state is asymmetric because of the density fluctuation for the amorphous structure. The loss peak frequency shifted to higher frequencies, and the relaxation strength increased with increasing CO2 pressure. In the glassy state, the shape of ε″ spectrum became more symmetric with increasing CO2 pressure. These show that the molecular mobility enhanced by the plasticization effect of CO2 allows the dipolar side groups in the high‐density region to contribute to the relaxation process. We also found that the apparent activation energy decreased under high‐pressure CO2. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2951–2962, 2005 相似文献
622.
Shigeo Sasaki Naoyuki Wada Tetsuji Kume Hiroyasu Shimizu 《Journal of Raman spectroscopy : JRS》2009,40(2):121-127
The pressure dependences of three adiabatic elastic constants, adiabatic bulk modulus, refractive index, and elastic anisotropy, as well as Cauchy deviation of fcc solid Xe have been determined up to 10 GPa at 296 K by high‐pressure Brillouin scattering spectroscopy. The characteristics of elastic properties at high pressure of rare‐gas solid Xe are investigated by comparison with the previous studies on Ne, Ar, and Kr. Above 10 GPa, the occurrence of splitting in the Brillouin signals and the direction dependence of acoustic velocities for solid Xe clearly show partial phase transformation to the hcp structure reported by the previous X‐ray diffraction and Raman scattering studies. The shear elastic modulus in the hcp phase of solid Xe has also been estimated at pressures up to 45 GPa by using the pressure dependence of the Raman wavenumber shift for the E2g mode. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
623.
To evaluate turbulence energy budget in bubbly flows, an image processing method in a photobleaching molecular tagging velocimetry is improved for accurate evaluation of velocity gradients. Turbulence properties in single-phase and two-phase dilute-bubbly flows in a square duct are measured using the improved method. As a result, the following conclusions are obtained: (1) The axial velocity and axial turbulent intensity measured by the present method agree well with those measured by laser Doppler velocimetry not only for the single-phase flow but also for the dilute-bubbly flow. (2) The present method can measure velocity components and velocity gradients in the vicinity of the wall, and therefore the present method is of great use in understanding the mechanism of turbulence generation and dissipation near the wall. (3) The present method can provide detailed information on turbulence structure such as turbulence kinetic energy budget. (4) Bubbles tend to increase not only the turbulence production but also the turbulence dissipation. 相似文献
624.
The super rotation here means that the majority of fluid inside a precessing sphere rotates around the precession axis with angular velocity larger than that of the precession rotation itself. This phenomenon observed experimentally and numerically is explained to be driven by a cooperative interplay between the Coriolis force, the pressure gradient and the spherical geometry in the boundary layer. 相似文献
625.
Pol VG Pol SV Gedanken A Kessler VG Seisenbaeva GA Sung MG Asai S 《The journal of physical chemistry. B》2005,109(13):6121-6125
We present the results of the RAPET (reaction under autogenic pressure at elevated temperatures) dissociation of CoZr(2)(acac)(2)(O(i)Pr)(8) at 700 degrees C in a closed Swagelok cell under an applied magnetic field of 10 T. It produces a mixture of carbon-coated and noncoated metastable ZrO(2) nanoparticles, bare metallic Co nanoparticles, and bare carbon. The same reaction in the absence of a magnetic field produces spherical Co and ZrO(2) particles in sizes ranging from 11 to 16 nm and exhibiting, at room temperature, metastable phases: fcc for cobalt and a tetragonal phase for zirconia. The metastable phases of Co and ZrO(2) are manifested because of a carbon shell of approximately 4 nm thickness anchored to their surfaces. The effect of an applied magnetic field to synthesize morphologically different, but structurally the same, products is the key topic of the present paper. 相似文献
626.
627.
Taisuke Nakanaga Shigeo Kondo Shinnosuke Saëki 《Journal of Molecular Spectroscopy》1980,81(2):413-423
The Coriolis interactions between ν1 and ν3, and between ν2 and ν3 in SO2 have been analyzed to obtain the signs of the products and . It has been found that both of the signs of these products are positive. Then, relative signs of () have been determined using the calculated values of the Coriolis zeta constants for the present definition of the normal coordinates. The obtained sign combination of () is ±(+?+), which agrees with the one predicted by the molecular orbital calculations. Using the sign combination (+?+), the polar tensors of S and O atoms were also calculated. 相似文献
628.
Susumu Tohno Masayuki Itoh Shigeo Aono Hiroshi Takano 《Journal of colloid and interface science》1996,180(2):574
Experiments were made to determine the dependence of the size of contact-free nanoparticles produced by aerosol process on gas pressure. The particles were collected as contact-free dispesoids in hexane with a cationic surfactant, and the geometric mean sizes were below 10 nm in diameter. It was found that the size increased linearly as the pressure was raised from 0.04 to 1.43 kPa for Ag, Bi, Cu, and Te. Similar slopes were obtained for the linear function between size and gas pressure except for Te. 相似文献
629.
630.
We have observed the formation of C2-60 and C2-70 in collisions between C(-)(60)/C(-)(70) and Na atoms. Cross sections for the electron transfer to the monoanion are determined to be 36+/-9 and 57+/-14 A(2) for C-60 and C-70, respectively. A simple model investigation suggests that the electron is transferred from a Na atom to a low-lying electronic state of the fullerene to form a dianion. The method leads to pico-ampere energetic beams of C60 dianions that can be used for spectroscopy and lifetime studies. 相似文献