The thirteen mother alloys,C%+1/3Si%=4.45%,differing in their Si,Ce,Sb and Sn contents,were prepared.Seventy grams of these alloys was remelted in a high purity alumina crucible at 1,450oC under an Ar atmosphere,and t...The thirteen mother alloys,C%+1/3Si%=4.45%,differing in their Si,Ce,Sb and Sn contents,were prepared.Seventy grams of these alloys was remelted in a high purity alumina crucible at 1,450oC under an Ar atmosphere,and then cooled at 30 K/min for obtaining their cooling curves.Their graphite morphologies were observed using an optical microscope and an SEM.Their three-dimensional graphite shapes were observed by the SEM using the samples whose matrices were etched off with an acid-aqua solution,to confirm the chunky graphite.For discussing the influence of the Si and Ce contents on the chunky graphite formation,two experiments were carried out.In the first one,the Si contents were changed from 0 to 4% in the 0.15%Ce alloys,and for the second one,the 3.5%Si and 4%Si samples that differed in the Ce contents of 0.1 and 0.2% were used.In the third experiment,the influence of Sb and Sn on the chunky graphite formation was investigated by using the 4%Si and 0.1%Ce samples.The results showed that with the increase of the Si content,the volume fraction of the chunky graphite increases,while the volume fraction of the ledeburite decreases,and the chunky graphite volume fraction in the 0.2%Ce samples is higher than that of the 0.1%Ce samples.The effect of the Sb and Sn additions on the prevention of chunky graphite formation cannot be confirmed due to their high Si contents.Therefore,further studies will be needed in this field.展开更多
The elasto-plastic finite element analyses for an interface crack in dissimilar material, based on the crack energy density (CED) concept, are investigated in mode I loading condition. It is confirmed that the values ...The elasto-plastic finite element analyses for an interface crack in dissimilar material, based on the crack energy density (CED) concept, are investigated in mode I loading condition. It is confirmed that the values of CED almost remain stable when the notch radius rho is sufficiently small, both in elastic and elasto-plastic case. Numerical results for both elastic and elasto-plastic cases show that under the mode I loading condition, when the crack propagates to the more stiff material with a small angle, the total CED will become larger than that along the interface. If the clack heads into the more compliant material, the CED will become less than that along the interface.展开更多
The characteristics of molecular motion of ferroelectric copolymer VDF(73)/TrFE(27) have been investigated by means of dielectric relaxation. With the rise in crystallinity, the Curie point decreases and the dielectri...The characteristics of molecular motion of ferroelectric copolymer VDF(73)/TrFE(27) have been investigated by means of dielectric relaxation. With the rise in crystallinity, the Curie point decreases and the dielectric constant increases in the region of ferroelectric-to-paraelectric phase transition. The frequency spectra of the copolymer below room temperature consist of low-frequency component ascribed to the micro-Brownian motions of molecular segments in the noncrystalline regions and high-frequency component associated with the local motions of small-scale segments. By using the fitting results with one or two Cole-Cole functions, and calculating with WLF equation acid Arrhenius formula,the glass transition temperature and the activation energy of local relaxation are obtained. the distribution of relaxation time in the molten and ferroelectric phases is located at a Same line, acid complies with Arrhenius rule, which suggests that the elementary motions are of same type for molecular motions provided by the high-temperature process and the low-temperature local mode process.展开更多
A new pregnane glycoside hypoglaucin G was isolated from Dioscorea collettii var. hypoglauca by bioactivity-guided fractionation, which showed a moderate activity of inducing morphological deformation of the Pyricular...A new pregnane glycoside hypoglaucin G was isolated from Dioscorea collettii var. hypoglauca by bioactivity-guided fractionation, which showed a moderate activity of inducing morphological deformation of the Pyricularia oryzae mycelia. The structure of hypoglaucin G was established as 16 beta-(4'-methyl-5'-O-beta-D-glucopyranosyl-pentanoyloxy)-pregn-5-en-3 beta-ol-20-one 3-O-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)-]-beta-D-glucopyranoside by chemical evidence and spectral analysis, especially by 2D-NMR techniques.展开更多
Dioscodn is the major storage protein of yam tuber and accounts for approximately 80%-85% of the total soluble proteins. The protein also exhibits the activities of carbonic anhy- drases （CAs） （Hou et al., 1999b, 2...Dioscodn is the major storage protein of yam tuber and accounts for approximately 80%-85% of the total soluble proteins. The protein also exhibits the activities of carbonic anhy- drases （CAs） （Hou et al., 1999b, 2000）展开更多
文摘The thirteen mother alloys,C%+1/3Si%=4.45%,differing in their Si,Ce,Sb and Sn contents,were prepared.Seventy grams of these alloys was remelted in a high purity alumina crucible at 1,450oC under an Ar atmosphere,and then cooled at 30 K/min for obtaining their cooling curves.Their graphite morphologies were observed using an optical microscope and an SEM.Their three-dimensional graphite shapes were observed by the SEM using the samples whose matrices were etched off with an acid-aqua solution,to confirm the chunky graphite.For discussing the influence of the Si and Ce contents on the chunky graphite formation,two experiments were carried out.In the first one,the Si contents were changed from 0 to 4% in the 0.15%Ce alloys,and for the second one,the 3.5%Si and 4%Si samples that differed in the Ce contents of 0.1 and 0.2% were used.In the third experiment,the influence of Sb and Sn on the chunky graphite formation was investigated by using the 4%Si and 0.1%Ce samples.The results showed that with the increase of the Si content,the volume fraction of the chunky graphite increases,while the volume fraction of the ledeburite decreases,and the chunky graphite volume fraction in the 0.2%Ce samples is higher than that of the 0.1%Ce samples.The effect of the Sb and Sn additions on the prevention of chunky graphite formation cannot be confirmed due to their high Si contents.Therefore,further studies will be needed in this field.
文摘The elasto-plastic finite element analyses for an interface crack in dissimilar material, based on the crack energy density (CED) concept, are investigated in mode I loading condition. It is confirmed that the values of CED almost remain stable when the notch radius rho is sufficiently small, both in elastic and elasto-plastic case. Numerical results for both elastic and elasto-plastic cases show that under the mode I loading condition, when the crack propagates to the more stiff material with a small angle, the total CED will become larger than that along the interface. If the clack heads into the more compliant material, the CED will become less than that along the interface.
文摘The characteristics of molecular motion of ferroelectric copolymer VDF(73)/TrFE(27) have been investigated by means of dielectric relaxation. With the rise in crystallinity, the Curie point decreases and the dielectric constant increases in the region of ferroelectric-to-paraelectric phase transition. The frequency spectra of the copolymer below room temperature consist of low-frequency component ascribed to the micro-Brownian motions of molecular segments in the noncrystalline regions and high-frequency component associated with the local motions of small-scale segments. By using the fitting results with one or two Cole-Cole functions, and calculating with WLF equation acid Arrhenius formula,the glass transition temperature and the activation energy of local relaxation are obtained. the distribution of relaxation time in the molten and ferroelectric phases is located at a Same line, acid complies with Arrhenius rule, which suggests that the elementary motions are of same type for molecular motions provided by the high-temperature process and the low-temperature local mode process.
文摘A new pregnane glycoside hypoglaucin G was isolated from Dioscorea collettii var. hypoglauca by bioactivity-guided fractionation, which showed a moderate activity of inducing morphological deformation of the Pyricularia oryzae mycelia. The structure of hypoglaucin G was established as 16 beta-(4'-methyl-5'-O-beta-D-glucopyranosyl-pentanoyloxy)-pregn-5-en-3 beta-ol-20-one 3-O-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)-]-beta-D-glucopyranoside by chemical evidence and spectral analysis, especially by 2D-NMR techniques.
文摘Dioscodn is the major storage protein of yam tuber and accounts for approximately 80%-85% of the total soluble proteins. The protein also exhibits the activities of carbonic anhy- drases （CAs） （Hou et al., 1999b, 2000）
