The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a ...The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a variety of human diseases, such as cerebrovascular disease, diabetes, tumor, isochemic heart diseases, hypertension, rheumatic arthritis, etc. E2,33. Flavonoids, a class of constituent compounds, which have a broad distribution in the nature and are found in Acanthopanax Senticosus Harms, have gained particular attention. A number of studies have shown that flavonoid compounds have wide biological activities, such as anti-aging, anticancer, anti-HIV,展开更多
Glycoalkaloids（GAS） have important biological and pharmaceutical activities, in order to study the relationship between the structures and the activities of carbohydrate chains, two natural glycoalkaloids, chaconine...Glycoalkaloids（GAS） have important biological and pharmaceutical activities, in order to study the relationship between the structures and the activities of carbohydrate chains, two natural glycoalkaloids, chaconine （compound 1 ） and solanine（ compound 2） , were isolated from potato stems and leaves（ Solanum tuberosum L. ）. The selective sulfation to the 6-hydroxy groups of chaeonine and solanine was carried out in a strategy by the use of protective groups. The 6-hydroxyl groups of the sugar chains in chaconine and solanine were protected with 4,4＇-dimethoxytrityl（DMT） while the other hydroxyl groups were acetylated. The protective group DMT was removed by using 0. 5% TFA in dichloromethane, The free 6-hydroxyl groups were sulfated by chlorosulfonic acid pyridine to give 6-O-sulfated products. After the acetyl groups were removed, the final products obtained were sulfated chaconine and sulfated solanine.^ 13C NMR spectra confirmed that chaconine and solanine were sulfated at O6 of the carbohydrate moiety.展开更多
Detection and manipulation of a single spin is essential for spin-based quantum information and computation.We propose an experimental method to detect the Larmor precession of a single spin with a spin-polarized tunn...Detection and manipulation of a single spin is essential for spin-based quantum information and computation.We propose an experimental method to detect the Larmor precession of a single spin with a spin-polarized tunneling current.The calculation demonstrates that the modulation of the tunneling current is significantly increased as compared with the non-spin-polarized current.The signal-to-noise ratio in the current power spectrum will be dramatically improved by this method.The longitudinal relaxation time can be measured by temporal control of spin orientation with pulses of magnetic field or radio frequency electromagnetic wave,while the transverse relaxation time can be derived by analyzing the resonant peak profile with a spectrum analyzer.Such ability in characterizing spin relaxation is of particular interest in providing insights into the coherence/decoherence of a single spin.展开更多
基金the Natural Science and Technology Foundation of Jilin Province(No 20020637-1)
文摘The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a variety of human diseases, such as cerebrovascular disease, diabetes, tumor, isochemic heart diseases, hypertension, rheumatic arthritis, etc. E2,33. Flavonoids, a class of constituent compounds, which have a broad distribution in the nature and are found in Acanthopanax Senticosus Harms, have gained particular attention. A number of studies have shown that flavonoid compounds have wide biological activities, such as anti-aging, anticancer, anti-HIV,
文摘Glycoalkaloids（GAS） have important biological and pharmaceutical activities, in order to study the relationship between the structures and the activities of carbohydrate chains, two natural glycoalkaloids, chaconine （compound 1 ） and solanine（ compound 2） , were isolated from potato stems and leaves（ Solanum tuberosum L. ）. The selective sulfation to the 6-hydroxy groups of chaeonine and solanine was carried out in a strategy by the use of protective groups. The 6-hydroxyl groups of the sugar chains in chaconine and solanine were protected with 4,4＇-dimethoxytrityl（DMT） while the other hydroxyl groups were acetylated. The protective group DMT was removed by using 0. 5% TFA in dichloromethane, The free 6-hydroxyl groups were sulfated by chlorosulfonic acid pyridine to give 6-O-sulfated products. After the acetyl groups were removed, the final products obtained were sulfated chaconine and sulfated solanine.^ 13C NMR spectra confirmed that chaconine and solanine were sulfated at O6 of the carbohydrate moiety.
基金Supported by the National Basic Research Program of China under Grant Nos 2012CB933002 and 2010CB923001the National Natural Science Foundation of China under Grant Nos 10974245 and 61027011.
文摘Detection and manipulation of a single spin is essential for spin-based quantum information and computation.We propose an experimental method to detect the Larmor precession of a single spin with a spin-polarized tunneling current.The calculation demonstrates that the modulation of the tunneling current is significantly increased as compared with the non-spin-polarized current.The signal-to-noise ratio in the current power spectrum will be dramatically improved by this method.The longitudinal relaxation time can be measured by temporal control of spin orientation with pulses of magnetic field or radio frequency electromagnetic wave,while the transverse relaxation time can be derived by analyzing the resonant peak profile with a spectrum analyzer.Such ability in characterizing spin relaxation is of particular interest in providing insights into the coherence/decoherence of a single spin.
