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971.
972.
This paper is concerned with the temperature dependence of mechanical properties of ultradrawn polyethylene in terms of storage modulus E' and loss factor tan by the measurement of the complex dynamic tensile modulus over ranges of temperature from 20 to 140 C. Interestingly, E' of a specimen with drawn ratio of 300 is about 120 GPa at 140 C, when the measurement is carried out at a frequency of 100 Hz. This is a very high value. In addition, the drawn specimens were irradiated to try to produce ultra-drawn polyethylene films with more excellent mechanical and thermal properties. However, the melting peak shifts to a lower temperature with increasing radiation dose. This result is probably attributed to the considerably radiation-induced scission of extended chains constructing crystals. 相似文献
973.
974.
Masamichi Tsuboi Akiko Y. Hirakawa Shuichi Muraishi 《Journal of Molecular Spectroscopy》1975,56(1):146-158
It has been shown how the Raman line of a degenerate vibration can be caused by a vibronic coupling in a degenerate electronic excited state. Such a vibronic coupling is known to cause a distortion in the equilibrium conformation of the molecule (Jahn-Teller distortion) from the symmetrical conformation, and the Raman scattering tensor is found to be calculated by the use of the amount (δ) of this distortion as an empirical parameter. It has been suggested that some of the Raman lines for the degenerate stretching vibrations, which become stronger with the exciting frequency, in some molecules, are caused by such Jahn-Teller couplings. For the intensity of the Raman line at 887 cm?1 of the degenerate stretching vibration of chromate anion, a slightly more detailed examination has been made, and the amount of the Jahn-Teller distortion in a (T2) electronic state has been estimated to be 0.20 Å amu1/2 along the normal coordinate of this vibration. 相似文献
975.
976.
A three-dimensional recirculation flow in a ventilated room was predicted by the numerical methods in which the turbulence models are applied. The predicted results are compared with the experimental results obtained in a model room in order to estimate the practical utilities of such methods from the viewpoint of engineering. Taking account of the practicability of prediction method which the engineers regard as important, two turbulence models were selected and they were incorporated into the numerical prediction methods respectively. One is the two-equation model, in which transport equations of turbulence energy and its rate of dissipation are adopted. The other is the Deardoff's model, in which the subgrid scale eddy coefficient is utilized. The prediction was made by each numerical method. Consequently, no noticeable difference is recognized between both predicted results. Each result is compared with the experimental results. Generally speaking, each agreement is good with regard to the mean velocity. Thus we can conclude that the numerical method using the two-equation model has more practical utility than that using Deardoff's model, because it can give the solutions in a shorter computer time. 相似文献
977.
978.
Microscopic analysis of carbon phases induced by femtosecond laser irradiation on single-crystal SiC
Takuro Tomita Tatsuya Okada Hiroyuki Kawahara Ryota Kumai Shigeki Matsuo Shuichi Hashimoto Masako Kawamoto Makoto Yamaguchi Shigeru Ueno Emi Shindou Akira Yoshida 《Applied Physics A: Materials Science & Processing》2010,100(1):113-117
Elemental analysis of femtosecond laser-induced modified region was carried out by transmission electron microscopy and Raman spectroscopy. The relative Raman intensities of a-SiC were higher in the peripheral region of laser irradiated spot where the fine ripple was formed. On the contrary, the relative Raman intensities of a-Si were higher in the central region where the coarse ripple was formed. This result suggests that the material migration has strongly occurred in the higher fluence region. On the other hand, the mapping of carbon atoms in the topmost amorphous layer of laser induced periodic structures did not show any significant segregation. In addition, Raman spectroscopic analysis showed that the domain size of carbon was very small (< 1 nm). From these facts, it was found that the carbon atoms were uniformly distributed in the topmost amorphous layer and were randomly connected without forming any observable fine particles. 相似文献
979.
Katsumi Shozugawa Motoyuki Matsuo Yuji Sano Yosuke Toh Yukihiro Murakami Kazuyoshi Furutaka Mitsuo Koizumi Atsushi Kimura Kaoru Hara Tadahiro Kin Masumi Oshima Shoji Nakamura Hideo Harada 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):341-346
Multiple prompt gamma-ray analysis (MPGA), a new radionuclide quantification method with high energy resolution, was applied to sediments from a marine shallow-water hydrothermal mound. Surface sediments around mounds were collected from the Wakamiko submarine crater located in Kagoshima Bay, southwest Japan, where the hydrothermal system was different from those at other marine shallow-water hydrothermal mounds. All samples were desalted and MPGA measurements were performed for 4,500?s (real time). Event data were obtained using eight Canberra-Eurisys CLOVER Ge detectors. The size of the list data that included all multiple events was from 1.19 to 19.2?GB. We could obtain concentrations of 32S, 55Mn, 75As, 157Gd, 39K, 149Sm, 56Fe, and 85Rb with high sensitivity by MPGA. Furthermore, 32S, 85Rb, and 55Mn have characteristic concentrations only at a mound, not at control sampling sites, suggesting that sediments were sulfurated by magmatic fluids at this mound. 相似文献
980.
Reduction of four bicyclic and two steroidal conjugated enones employing diisobutylaluminum hydride (DIBAL) in tetrahydrofuran (THF)/1,2-dimethoxyethane (DME) led to allylic alcohols with high levels of diastereo-selectivity. 相似文献