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31.
The cyclic deformations under various repeated stresses are quantitatively investigated using non-linear viscoelastic cellulose nitrate heated to 60° C. The non-elastic strain or creep-plastic strain is remarkably influenced by the repeated stress and the stress rate. The cyclic deformations corresponding to the repeated stress less than a certain stress level attain the saturated state called the shake down after some cycles. The stress-strain relations of the non-linear viscoelastic media in the loading and unloading processes are deduced from the invariant theory using an hypothesis of creep potential. The non-linear viscoelastic observations obtained on the cellulose nitrate at 60° C under cyclic loadings are found to fit the deduced relations for the loading and unloading processes independent of the repeated stress and the stress rate. 相似文献
32.
Taxonomy for protective ability of rust layer using its composition formed on weathering steel bridge 总被引:2,自引:0,他引:2
For a quantitative evaluation of the protectiveness of a rust layer formed on a weathering steel bridge, the relationship between the corrosion rate of the bridge and the composition of the rust layers formed on the girders was first investigated. These corrosion rates were clearly classified by the protective ability index (PAI) of α/γ∗ and (β + s)/γ∗, where α, γ∗, β and s are the mass ratio of crystalline α-FeOOH, the total of γ-FeOOH, β-FeOOH and the spinel-type iron oxide (mainly Fe3O4), β-FeOOH and spinel-type iron oxide, analyzed by XRD, respectively. The inequality of the former index α/γ∗ > 1 expressed the protectiveness criterion of the rust layer, while that of the latter index, (β + s)/γ∗< 0.5 or > 0.5, classified the corrosion rate of the non-protective rust layer. The PAI is useful for a quantitative evaluation of the protectiveness of a rust layer formed on a weathering steel bridge and is an important item for the corrosion assessment of the bridge. 相似文献
33.
Zempachi Ogumi Hiroya Yamashita Koji Nishio Zen-Ichiro Takehara Shiro Yoshizawa 《Electrochimica acta》1983,28(11):1687-1693
The feasibility of a solid polymer electrolyte (SPE) method for Kolbe type reactions was investigated by using Pt-SPE composed with Nafion 415 and platinum. The Kolbe reaction of acetic acid proceeded effectively on one side and both sides Pt-SPE composites. The lower current efficiency was observed on the latter than on the former. Neat acetic acid could also be electrolysed on both sides SPE though the cell voltage was fairly high.A methanolic solution of monomethyl adipate was electrolysed to give dimethyl sebacate on both sides Pt-SPE according to the Brown-Walker reaction. The current efficiency and the terminal voltage increased with the concentration of monomethyl adipate. Pt-SPE behaved as an active electrode of a high roughness factor, eg about 6, for the Kolbe reaction of acetate. 相似文献
34.
Shoji Watanabe Kyoichi Suga Tsutomu Fujita Nobuo Takasaka 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1974,24(11):639-643
Various terpene alcohols were prepared from isoprene oligomers via two steps: epoxidation with peracetic acid and isomerisation with aluminium triisopropoxide. For example, 2-methylene-6-methyl-7-octene-1-o1 was prepared from 2,6-dimethyl-1,7-octadiene. From 2,6-dimethyl-2,7-octadiene, 3,3,6-trimethyl-1,5-heptadiene, 2,7-dimethyl-2,6-octadiene, 2,6-dimethyl-1,3,6-octatriene, 1-methyl-4-isopropenyl-1-cyclohexene, and 1,5-dimethyl-1,5-cyclooctadiene, the corresponding alcohols were obtained, respectively. 相似文献
35.
Kimihiro Yamashita Motohide Matsuda Yasushi Inda Takao Umegaki Masayuki Ito Toshinori Okura 《Journal of the American Ceramic Society》1997,80(7):1907-1909
Dielectric depression and dispersion were observed in BaTiO3 ceramic films fabricated by electrophoretic deposition followed by sintering. The dielectric constants were depressed down to 6800–4600 around the Curie point ( T C ). The dielectric dispersion occurred above T C . These dielectric properties are attributable to a surface layer formed during sintering. XRD analysis indicated that the surface layer was a hexagonal-like BaTiO3 phase. A mixed solvent of acetylacetone and alcohol employed in the present work may have been responsible for the formation of the surface layer. 相似文献
36.
37.
Effects of bile acid feeding on hepatic deoxycholate 7α-hydroxylase activity in the hamster 总被引:1,自引:0,他引:1
In order to investigate the effects of bile acid feeding on hepatic microsomal deoxycholate 7α-hydroxylase activity, three
different bile acids were administered (0.2% w/w in chow) to hamsters for two weeks. Deoxycholate 7α-hydroxylase activity
was increased markedly by feeding of cholic acid (CA) and slightly by deoxycholic acid (DCA) Chenodeoxycholic acid (CDCA)
had little effect on the enzyme activity. Feeding each of the bile acids significantly inhibited the activity of cholesterol
7α-hydroxylase in the order CDCA≥ DCA>CA. There was no correlation between deoxycholate 7α-hydroxylase activity and cholesterol
7α-hydroxylase activity. It is concluded that the activity of deoxycholate 7α-hydroxylase is up-regulated by feeding DCA and
CA and that the mechanism seems to be different from that of cholesterol 7α-hydroxylase. The increased activity of hepatic
deoxycholate 7α-hydroxylase by CA and DCA should be beneficial in minimizing the toxic effects of DCA in the hamster. 相似文献
38.
Tsutomu Osawa Masashi Ando Saori Sakai Tadao Harada Osamu Takayasu 《Catalysis Letters》2005,105(1-2):41-45
The role of acetic acid added to the reaction media for the enantio-differentiating hydrogenation of methyl acetoacetate over
a (R,R)-tartaric acid-in-situ-modified nickel catalyst was studied from the viewpoint of the hydrogenation rate during repeated
runs. The hydrogenation of methyl acetoacetate on the “enantio-differentiating sites” of a tartaric acid-modified nickel catalyst
was specifically accelerated by the acetic acid added to the reaction media to increase the enantio-differentiating ability
of the catalyst. In order to increase the enantio-differentiating ability, the addition of acetic acid to the reaction media
was required in each run during the repeated use of the catalyst. 相似文献
39.
We have developed a reel-to-reel microchip mounting system that continuously mounts LED chips and other microchips on meter-long flexible printed circuit board (PCB) tape for 1.2-m-long standard LED light tubes. Mounting microchips on meter-long PCBs is difficult because a large chip mounter is expensive and the chip positioning stage is difficult to move in a meter-wide area with an accuracy of hundreds of micrometers. Hence, we developed a new microchip mounting system that utilizes a small chip mounter and reel winding machines. The system repeatedly moves the long PCB tape by a certain length with the reel winding machines and mounts the chips on it. The PCB tape (which is 5 mm wide) is made by fabricating long PCB tapes which are 25 cm × 26.6 m through a roll-to-roll PCB process and slitting them into meter-long tapes. The reel-to-reel system repeatedly mounts chips by adjusting their positions through image processing of the copper wiring pattern on the PCBs. Our constructed system mounted 24 LED chips with a pitch of 5 cm with an accuracy of 0.082 mm to form a 1.2-m-long LED tape. The luminance of the tape is 12.4 lx at a distance of 1 m, which is the luminance of outdoor corridor lighting. Therefore, this system can be used for meter-long tape lighting. 相似文献
40.
Masahiro Tatsumisago Tsutomu Minami Masami Tanaka 《Journal of the American Ceramic Society》1981,64(7):97-C-
A new technique combining a thermal-image furnace and a twin roller is described for quenching the melt to form glass. The technique was applied to the simple system Li2 O-SiO2 , since its fundamental parameters in the estimation of critical cooling rate are available. Glass flakes were obtained in the composition Li4 SiO4 , for which a very large critical cooling rate (∼109 K·s−1 ) was needed for glass formation. 相似文献