Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, ...Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, bud2, which results from the complete deletion of one member of the small gene family that encodes S-adenosylmethionine decarboxylases （SAMDCs） necessary for the formation of the indispensable intermediate in the polyamine biosynthetic pathway. The bud2 plant has enlarged vascular systems in inflorescences, roots, and petioles, and an altered homeostasis ofpolyamines. The double mutant of bud2 and samdcl, a knockdown mutant of another SAMDC member, is embryo lethal, demonstrating that SAMDCs are essential for plant embryogenesis. Our results suggest that polyamines are required for the normal growth and development of higher plants.展开更多
Oxidative desulfurization was performed on Na2WO4 catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions （atmospheric pressure and temperature range of 293--343 K）. Different or...Oxidative desulfurization was performed on Na2WO4 catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions （atmospheric pressure and temperature range of 293--343 K）. Different organic compounds including benzothiophene （BT）, dibenzothiophene （DBT）, 4, 6-dimethyl dibenzothiophene （4, 6-DMDBT） were used to investigate the reactivity of this catalyst, and the effect of various parameters, such as temperature, solvents and the amount of oxidant reagent used in oxidative desulfurization reaction, was also examined. The results showed that the Na2WO4- H202 system was very effective for oxidative desulfurization, and the oxidation of BT, DBT and 4, 6-DMDBT was influenced by different parameters.展开更多
The separations of single-wall carbon nanotubes on length by sepharose gel were investigated in this work. The solutions of sodium dodecyl sulfate and sodium deoxycholate were applied as the eluent in sequence. SEM an...The separations of single-wall carbon nanotubes on length by sepharose gel were investigated in this work. The solutions of sodium dodecyl sulfate and sodium deoxycholate were applied as the eluent in sequence. SEM and Raman were used to characterize the length of nanotube bundles. The results show that the longer nanotubes were eluted out first, and then the shorter tubes were followed by the sodium dodecyl sulfate. However, the separated order was totally reversed by the sodium deoxycholate. By this method, the process generated nanotube fractions not only were narrower in length distributions, but also could control the separation orders by changing the eluents. Moreover, the separation principle was also discussed.展开更多
We present a systematic study of the effects of surfactants in the separation of single-walled carbon nanotubes （SWNTs） by density gradient ultracentrifugation （DGU）. Through analysis of the buoyant densities, lay...We present a systematic study of the effects of surfactants in the separation of single-walled carbon nanotubes （SWNTs） by density gradient ultracentrifugation （DGU）. Through analysis of the buoyant densities, layer positions, and optical absorbance spectra of SWNT separations using the bile salt sodium deoxycholate （DOC） and the anionic salt sodium dodecyl sulfate （SDS）, we clarify the roles and interactions of these two surfactants in yielding different DGU outcomes. The separation mechanism described here can also help in designing new DGU experiments by qualitatively predicting outcomes of different starting recipes, improving the efficacy of DGU and simplifying post-DGU fractionation.展开更多
基金We thank Dr Senya Matsufuji(Jikei University,Japan)for providing the yeast spe2 strain,Dr Guixian Xia(Institute of Microbiology,Chinese Academy of Sciences,China)for yeast expression vector pREP5N and ABRC stock center for BAC clones(F17K4 and T16G12)and T-DNA insertion lines(Salk_007279 and Salk_020185).This work was supported by grants from National Natural Science Foundation of China(30330040)the Ministry of Sciences and Technology of China(J02-A-001).
文摘Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, bud2, which results from the complete deletion of one member of the small gene family that encodes S-adenosylmethionine decarboxylases （SAMDCs） necessary for the formation of the indispensable intermediate in the polyamine biosynthetic pathway. The bud2 plant has enlarged vascular systems in inflorescences, roots, and petioles, and an altered homeostasis ofpolyamines. The double mutant of bud2 and samdcl, a knockdown mutant of another SAMDC member, is embryo lethal, demonstrating that SAMDCs are essential for plant embryogenesis. Our results suggest that polyamines are required for the normal growth and development of higher plants.
文摘Oxidative desulfurization was performed on Na2WO4 catalyst in the presence of hydrogen peroxide and acetic acid under mild reaction conditions （atmospheric pressure and temperature range of 293--343 K）. Different organic compounds including benzothiophene （BT）, dibenzothiophene （DBT）, 4, 6-dimethyl dibenzothiophene （4, 6-DMDBT） were used to investigate the reactivity of this catalyst, and the effect of various parameters, such as temperature, solvents and the amount of oxidant reagent used in oxidative desulfurization reaction, was also examined. The results showed that the Na2WO4- H202 system was very effective for oxidative desulfurization, and the oxidation of BT, DBT and 4, 6-DMDBT was influenced by different parameters.
基金supported by the National Science & Technology Pillar Program of MOST (Grant No. 2011BAK15B04)
文摘The separations of single-wall carbon nanotubes on length by sepharose gel were investigated in this work. The solutions of sodium dodecyl sulfate and sodium deoxycholate were applied as the eluent in sequence. SEM and Raman were used to characterize the length of nanotube bundles. The results show that the longer nanotubes were eluted out first, and then the shorter tubes were followed by the sodium dodecyl sulfate. However, the separated order was totally reversed by the sodium deoxycholate. By this method, the process generated nanotube fractions not only were narrower in length distributions, but also could control the separation orders by changing the eluents. Moreover, the separation principle was also discussed.
基金Acknowledgements Part of this work was financially supported by Grant- in-Aid for Scientific Research （No. 22226006 and 19054003）, ＂Development of Nanoelectronic Device Technology＂ of New Energy and Industrial Technology Development Organization （NEDO）, and the Global Centers of Excellence （COE） Program ＂Global Center for Excellence for Mechanical Systems Innovation＂. P. Z. acknowledges a scholarship granted by the China Scholarship Council and G. L. acknowledges support from the NanoJapan program funded by the National Science Foundation.
文摘We present a systematic study of the effects of surfactants in the separation of single-walled carbon nanotubes （SWNTs） by density gradient ultracentrifugation （DGU）. Through analysis of the buoyant densities, layer positions, and optical absorbance spectra of SWNT separations using the bile salt sodium deoxycholate （DOC） and the anionic salt sodium dodecyl sulfate （SDS）, we clarify the roles and interactions of these two surfactants in yielding different DGU outcomes. The separation mechanism described here can also help in designing new DGU experiments by qualitatively predicting outcomes of different starting recipes, improving the efficacy of DGU and simplifying post-DGU fractionation.
