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1.
Per B. Zetterlund Kazuki Miyake Kunihiro Goto Bunichiro Yamada 《Journal of polymer science. Part A, Polymer chemistry》2004,42(11):2640-2650
A detailed investigation of addition–fragmentation chain transfer (AFCT) in the free‐radical polymerization of methyl methacrylate (MMA) in the presence of methyl α‐(bromomethyl)acrylate (MBMA) was carried out to elucidate mechanistic details with efficient macromonomer synthesis as an underlying goal. Advanced modeling techniques were used in connection with the experimental work. Curve fitting of simulated and experimental molecular weight distributions with respect to the rate coefficient for addition of propagating radicals to MBMA (kadd) over 60–120 °C resulted in Eadd = 21.7 kJ mol?1 and Aadd = 2.18 × 106 M?1 s?1 and a very weak temperature dependence of the chain‐transfer constant (Eadd ≈ Ep). The rate coefficient for fragmentation of adduct radicals at 60 °C was estimated as kf ≈ 39 s?1 on the basis of experimental data of the MMA conversion and the concentration of 2‐carbomethoxy‐2‐propenyl end groups. The approach developed is generic and can be applied to any AFCT system in which copolymerization does not occur and in which the resulting unsaturated end groups do not undergo further reactions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2640–2650, 2004 相似文献
2.
K.J. Liu M. Miyake P.E. James H.M. Swartz 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,133(2):291-298
Carbon based paramagnetic materials are frequently used for EPR oximetry, especiallyin vivo,but the EPR spectra of these materials often have more than one paramagnetic center and/or relatively low signal intensity. To determine whether the multi-components of carbon based materials could be separated and enriched in the active component, we used density gradient centrifugation to separate the materials into several fractions. We studied two types of coals, gloxy and Pocahontas, and found these materials to have large density distribution. The separated density fractions had very different EPR spectra and intensities. The active component from the coal material had a more homogeneous EPR signal and significantly increased EPR signal intensity, whereas for India ink, only slight changes were observed. This result can be very useful in the development of better probes for EPR oximetry. 相似文献
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S Amagaya K Harada A Miyake H Iwama Y Ogihara 《Chemical & pharmaceutical bulletin》1989,37(4):1117-1119
The direct addition of levamisole to murine splenic lymphocytes had no effect on the mitogenic activity of lipopolysaccharide. However, the addition of serum of mice orally treated with levamisole increased the mitogenic activity, and this increased activity using serum was similar to the result obtained in an in vivo experiment. These results suggest that the new in vitro experimental method using serum may be able to reproduce the in vivo effect of drugs. 相似文献
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Kunihito Miyake Yasuhiro Masaki Ikuya Miyamoto Shozo Yanagida Takeshi Ohno Akio Yoshimura Chyongjin Pac 《Photochemistry and photobiology》1993,58(5):631-636
We have investigated the photosensitized monomerization of the cis,syn -cyclobutane dimer of 1,3-di-methylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg2+ . The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO4 on the flavin-photosensitized reaction. 相似文献
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K. Nagamine Y. Miyake P. Birrer K. Shimomura M. Iwasaki T. Kuga J. Marangos 《Hyperfine Interactions》1994,87(1):1083-1089
A concept, a construction and an account of commissioning experiments up to May 1993 are given for the recently completed ultra-slow positive muon facility at the pulsed muon facility of UT-MSL/KEK. The intense and ultra-slow
+ beam with an extremely small phase-space volume to be produced in this facility will open new muon sciences includingSR studies on material surfaces. 相似文献
10.
K. Nagamine Y. Miyake P. Birrer K. Shimomura M. Iwasaki K. Nishiyama P. Strasser T. Kuga J. Marangos 《Hyperfine Interactions》1993,80(1-4):1287-1295
A concept, a design, a construction and an account of commissioning experiments are given for the recently completed ultra-slow muon facility at the pulsed muon facility of UT-MSL/KEK. The intense (more than 103/s) slow + beam with an extremely narrow phase-space volume (0.2 eV×(3 cm)2) to be produced in this facility will open a new muon science including surface physics and chemistry and fundamental atomic physics.Post-doctoral fellow of Swiss National Science Foundation. 相似文献