A new triterpene glycoside, leucospilotaside A, along with a known saponin, isolated from sea cucumber Holothuria leucospilota, and its structure was elucidated as 3β-O-[4-O-sodiumsulfate-β-d-quinovopyranosyl-(1 → ...A new triterpene glycoside, leucospilotaside A, along with a known saponin, isolated from sea cucumber Holothuria leucospilota, and its structure was elucidated as 3β-O-[4-O-sodiumsulfate-β-d-quinovopyranosyl-(1 → 2)-β-d-xylopyranosyl]-holosta-22-ketone-9-en-17α,25α-diol (1) by extensive spectroscopic analysis and chemical methods. Leucospilotaside A (1) has a ketone carbonyl group (22) in the aglycon side chain.展开更多
A new triterpene glycoside, leucospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-0-{4′-O-s...A new triterpene glycoside, leucospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-0-{4′-O-sodiumsulfate-β′-D-xylopyranosyl}- holosta-22,25-epoxy-9-ene-3β,12α,17α-triol （1） by extensive spectroscopic analysis and chemical methods. The glycosides have the same triterpene aglycone, but differ in the oligosaccharide moieties.展开更多
Cold atmospheric-pressure He +N2 and He +O2 plasmas are chosen as the representatives for electropositive andelectronegative plasmas, of which the discharge characteristics are studied and then compared to each other ...Cold atmospheric-pressure He +N2 and He +O2 plasmas are chosen as the representatives for electropositive andelectronegative plasmas, of which the discharge characteristics are studied and then compared to each other by fluidmodels. As the increase of the impurity (N2 or O2) fraction from 0 to 10%, for He + N2 plasmas the electron density andion density increase, the spatiotemporal distributions of electron density, ion density, electron temperature and electrongeneration rate change a little. On contrast, for He + O2 plasmas the electron density decreases, the ion density firstincreases and then decreases, the electron temperature increases in the bulk region, but decreases in the sheath region,and the plasmas transform from g mode to α mode as the significant change of electron generation rate distributions.Larger electric field is needed in the bulk region to sustain the electronegative plasma, so the electrical characteristics ofHe + O2 plasmas transform form capacitive to resistive with increasing O2 fraction. Meanwhile, the ion-coupling powerincreases dramatically, which can be estimated by a formula based on the electronegativity. A new criterion fordetermining the sheath boundary, |∇E| = 5 kV/cm2, is put forward, which is found suitable for both the electropositive andelectronegative plasmas.展开更多
文摘A new triterpene glycoside, leucospilotaside A, along with a known saponin, isolated from sea cucumber Holothuria leucospilota, and its structure was elucidated as 3β-O-[4-O-sodiumsulfate-β-d-quinovopyranosyl-(1 → 2)-β-d-xylopyranosyl]-holosta-22-ketone-9-en-17α,25α-diol (1) by extensive spectroscopic analysis and chemical methods. Leucospilotaside A (1) has a ketone carbonyl group (22) in the aglycon side chain.
基金supported by the State Foundation for High-tech Project"863"from the Ministry of Science and Technology,China (No.2001AA624100)grant from National Natural Science Foundation of China (No.20772155).
文摘A new triterpene glycoside, leucospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-0-{4′-O-sodiumsulfate-β′-D-xylopyranosyl}- holosta-22,25-epoxy-9-ene-3β,12α,17α-triol （1） by extensive spectroscopic analysis and chemical methods. The glycosides have the same triterpene aglycone, but differ in the oligosaccharide moieties.
基金the National Science Foundation of China(Grant No.51521065)the Fundamental Research Funds for the Central Universities and the State Key Laboratory of Electrical Insulation and Power Equipment(Grant No.EIPE14123).
文摘Cold atmospheric-pressure He +N2 and He +O2 plasmas are chosen as the representatives for electropositive andelectronegative plasmas, of which the discharge characteristics are studied and then compared to each other by fluidmodels. As the increase of the impurity (N2 or O2) fraction from 0 to 10%, for He + N2 plasmas the electron density andion density increase, the spatiotemporal distributions of electron density, ion density, electron temperature and electrongeneration rate change a little. On contrast, for He + O2 plasmas the electron density decreases, the ion density firstincreases and then decreases, the electron temperature increases in the bulk region, but decreases in the sheath region,and the plasmas transform from g mode to α mode as the significant change of electron generation rate distributions.Larger electric field is needed in the bulk region to sustain the electronegative plasma, so the electrical characteristics ofHe + O2 plasmas transform form capacitive to resistive with increasing O2 fraction. Meanwhile, the ion-coupling powerincreases dramatically, which can be estimated by a formula based on the electronegativity. A new criterion fordetermining the sheath boundary, |∇E| = 5 kV/cm2, is put forward, which is found suitable for both the electropositive andelectronegative plasmas.
