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41.
Takeshi Yagi Kazuo Shinozaki Nobuo Ishizawa Nobuyasu Mizutani Masanori Kato Akihiko Tsuge 《Journal of the American Ceramic Society》1988,71(7):334-C
The thermal diffusivity of AlN ceramics was significantly decreased by the addition of SiO2 . The AlN ceramics with 4 wt% SiO2 could not be densified by pressureless sintering in the temperature range 1400° to 1800°C. The thermal diffusivity of these samples was very low because of their porous structure. The AlN ceramics containing 2, 4, and 8 wt% SiO2 were densified by hot-pressing and also had low thermal diffusivity. In these samples, the grains of the 27R polytype that resulted from the reaction between AlN and SiO2 were dispersed, obstructing the conduction of heat. The relation between the amount of 27R polytype and the thermal diffusivity of the AlN ceramics was determined. 相似文献
42.
A new technique detecting molecular motions in drawn polymers was applied to highly cold-drawn polycarbonate of bisphenol A. It is shown that the sample exhibits thermal shrinkage in three steps with the temperature increase up to above the glass transition temperature. The molecular relaxation at the highest temperature is due to the glass transition. The other two molecular motions at the lower temperature are those of main chain in the glassy state and they correspond to the molecular motions as revealed in dielectric measurement by Sacher.1 By using the general theory of the thermal analysis by Ozawa,2 the apparent activation energies of these molecular motions were obtained: for the highest temperature 110 kcal/mole, and for the lowest temperature, 33.5 kcal/mole. The impact strength and the cold workability of this polymer are also discussed in relation to these molecular motions. 相似文献
43.
A fractal approach is adopted to describe the dynamic behavior of a circulating fluidized bed. Two times series, differential pressure fluctuations along the riser height and solids momentum fluctuations along the radial direction, are measured and analyzed in terms of fractal dimensions. The influences of operating conditions and axial/radial positions on the fractal dimension are discussed. Attempts are also made to interpret the flow structure in the bed in terms of the fractal dimension. It is found that fractal analysis can provide a useful tool for understanding the characteristics of gas-solids flow in circulating fluidized beds. 相似文献
44.
Male Wistar rats were fed for 4 wk on diets containing 2% oxidized corn oil. Liver tissue was then studied to determine the
effect of feeding peroxidized oil on lipogenic enzymes. Although substances which reacted with thiobarbituric acid increased
in liver microsomes and mitochondria with increasing peroxide values of the dietary corn oil fed, the activities of glucose-6-phosphate
dehydrogenase, malic enzyme and acetyl-CoA carboxylase in liver were unchanged. However, when rats were fed for 2 wk on diets
containing 10% fat, of which 0.5, 5 or 10% was unoxidized corn oil and the remainder was hydrogenated beef tallow filler,
the lipogenic enzyme activities and also the liver triglyceride levels were observed to decrease with increasing amounts of
dietary corn oil. Therefore, although a synthetic diet containing corn oil was easy to oxidize spontaneously, the reductions
of lipogenic enzymes in rats fed the diet would not have been caused by lipid peroxides but by unsaturated fatty acids themselves. 相似文献
45.
K. Sakata K. Kato Y. Iwase H. Okada K. Ina Y. Machiguchi 《Journal of chemical ecology》1991,17(1):185-193
Phagostimulant activity of glycerolipids such as digalactosyldiacylglycerol (DGDG), 6-sulfoquinovosyldiacylglycerol (SQDG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), etc., have been examined using the Avicel plate method for three kinds of marine herbivorous gastropods, the abaloneHaliotis discus, the turban shellTurbo cornutus, and the topshellOmphalius pfeifferi. DGDG showed strong activity for all the test animals. SQDG was much less active than the other glycerolipids for abalone. The turban shell and the top shell responded more or less sensitively to all tested glycerolipids at doses of 10–20g/sample zone.Chemical Studies on Phagostimulants for Marine Gastropods. Part VIII. For Part VII, see Sakata et al. (1988a). 相似文献
46.
Fumiaki Kobayashi Toru Ogawa Mitsuo Akabori Yoshio Kato 《Journal of the American Ceramic Society》1995,78(8):2279-2281
Uranium-plutonium nitride is a candidate fuel for fast reactors, but its major drawback is 14 C formation from natural nitrogen. One would probably have to use highly 15 N-enriched nitrogen. A pyrochemical process with molten-salt electroreflning has been proposed as a means to increase the nuclear proliferation resistance of the fuel cycle. Molten-salt electroreflning could also be applied to nitride fuels to make possible the recycling of 15 N. The anodic dissolution behavior of UN in LiCI-KCI melt was studied to provide the basis for a feasibility study of electroreflning of irradiated nitride fuels. 相似文献
47.
Influence of tetrabutyl-, tetrapentyl- and tetraisopentylammonium ions on the reduction of nickel(II) in thiocyanate solutions at the dropping mercury electrode has been investigated. These tetraalkylammonium ions, at their low concentrations, inhibit the reduction of nickel(II). However, at their high concentrations, the strong inhibiting effect disappers with the formation of a new wave corresponding to the reduction of a negatively charged nickel(II) thiocyanate complex, which is stabilized by the formation of ion pair with tetraalkylammonium cation. The variation of the reduction current with tetraalkalylammonium concentration was explained by taking into consideration both the change of the total charge of nickel(II) thocyanate complex involved in the reduction process and the simultaneous adsorption of tetraalkylammonium and thiocyanate ions on the mercury electrode. 相似文献
48.
The liver lipogenic enzymes are compared among rats, chickens, frogs and fish. Although the apparent Km values of glucose-6-phosphate
dehydrogenase for glucose-6-phosphate are not much different among all the species, those of malic enzyme for malate are much
higher in chickens and fish than in rats and frogs. Glucose-6-phosphate dehydrogenase showed very high activities compared
with malic enzyme in fish liver, and malic enzyme showed high activities in chicken liver. Although the apparent Km values
of acetyl-CoA carboxylase and fatty acid synthetase for substrates are in the same range among all the animals, the activity
of acetyl-CoA carboxylase seems to be extremely low in fish and frog livers, and that of fatty acid synthetase is low in frog
livers only. In addition, the apparent Km values of α-glycerophosphate acyltransferase of fish liver are very high, and the
enzyme activity appears to be extremely low compared to the others. Therefore, the enzymes at the first steps of both fatty
acid and glycerolipid syntheses of poikilothermos animals appear to be very low. On the other hand, the Ouchterlony double-diffusion
patterns showed that the lipogenic enzymes of chickens, frogs and fish are immunologically different from those of rats, with
the exception of acetyl-CoA carboxylase in chickens. Therefore, it is suggested that the fatty acid and glycerolipid forming
systems of poikilothermos animals are quite different from those of homoiothermos and the lipogenesis is very low in poikilothermos. 相似文献
49.
Ichiro Kudo Toshiyuki Kato Hidetoshi Hayashi Ryohei Yanoshita Koichi Ikizawa Hiroko Uda Keizo Inoue 《Lipids》1991,26(12):1065-1070
We have previously reported that platelet-activating factor (PAF) induces proliferation and microbicidal activity of guinea
pig bone marrow cells. In the present study, we have found that the conditioned medium of PAF- or nonmetabolizable PAF agonist-treated
guinea pig bone marrow cells augmented DNA synthesis and induced microbicial activity of bone marrow cells. A PAF specific
antagonist, CV-6209, inhibited generation of the active conditioned medium by PAF. Addition of the PAF antagonist only partially
suppressed the augmentative effect of the active conditioned medium on DNA synthesis; this is consistent with the fact that,
because of the rapid breakdown, no appreciable amount of PAF remained in the conditioned medium of PAF-treated cells. Although
mouse bone marrow cells did not respond to PAF unlike guinea pig cells, their DNA synthesis was significantly enhanced by
the conditioned medium of PAF-treated guinea pig bone marrow cells. Thus, some newly generated factor(s) distinct from the
originally inoculated PAF seemed to modulate the bioactions of PAF on bone marrow cells. An appreciable amount of PAF was
produced by calcium ionophore-treated guinea pig bone marrow cells. These findings indicate that PAF synthesized in guinea
pig bone marrow cells induces generation in the cells of some factor(s) which affects proliferation or microbicidal activity.
Presented at The Third International Conference on Platelet-Activating Factor and Structurally Related Ether Lipids, Tokyo,
Japan, May 1989. 相似文献
50.
The agronomic effectiveness of two natural phosphate rocks (PRs) from North Carolina (USA) and Togo and their 50% partially acidulated products (PAPRs) was evaluated in two greenhouse experiments using32P isotopic dilution techniques, namely L and AL values.In the first experiment rye grass was grown in a soil from Ghana. While the proportion of P in the plant derived from the P fertilizer (Pdff) ranged on. the average from about 10% for the PRs up to 80% for the PAPRs, the P fertilizer recovery was less than 1% for a 60-day growth period. In the second experiment, average values of P in the maize plants derived from the PAPRs ranged from 35% to 75% in 3 different soils. Both PRs were ineffective with the exception of North Carolina PR in the Seibersdorf soil. The P fertilizer recovery was 0.25% for the North Carolina PR in this soil whereas the recovery values ranged from 1.2% to 1.6% for the PAPRs.Mean values of the relative fertilizer efficiency estimated from the L values of each soil were less than 1% for the PRs whereas the values for the PAPRs which were dependent on soil type ranged from 20% up to 45%. The coefficient of relative effect of partial acidulation, that was calculated from the ratio of AL values for PR and PAPR in each soil indicated that partial acidulation increased the effectiveness of the natural PRs in all soils under study.This study showed that the use of32P isotope dilution techniques allows an accurate measurement of the P availability from natural and modified PR products to crops. Another advantage is that quantitative comparison of the P sources under study, PRs and PAPRs in this case, can be made even in soils where there is no response to the applied P sources. 相似文献