Two new sesquiterpene lactone glycosides were isolated from the seeds of Carpesium macrocephalum. Their structures were elucidated as 2-O--D-glucopyranosy-5? 11?H- eudesma-4 (15)-en-12, 8?olide and 2 ?O--D-glucopyran...Two new sesquiterpene lactone glycosides were isolated from the seeds of Carpesium macrocephalum. Their structures were elucidated as 2-O--D-glucopyranosy-5? 11?H- eudesma-4 (15)-en-12, 8?olide and 2 ?O--D-glucopyranosy-5?H-eudesma-4 (15), 11 (13)- dien-12, 8?olide by spectral methods (HRMS, 1 D and 2 D NMR).展开更多
ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have beensynthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO_2,silica sol as the source of aluminum and sil...ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have beensynthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO_2,silica sol as the source of aluminum and silica, respectively, and TEA^+ as the template undercontrolled condition of the synthesis. The ZSM-5/β co-crystalline zeolite was studied by XRD, SEM,BET and NH_3-TPD. The reaction activity of toluene alkylation was investigated with a mixture oftoluene-methanol as the feedstock in a pulse micro-reactor over the ZSM-5/β co-crystalline zeolite.It is found that ZSM-5/β co-crystalline zeolite has two kinds of zeolite structure including ZSM-5and β zeolite, not in the form of a physical mixture. The pore structure of ZSM-5/βco-crystalline zeolites is different from that for β zeolite, ZSM-5 and their physical mixture. Inaddition, the peaks of both high and low temperature desorption of ammonia over the ZSM-5/βco-crystalline zeolite shift 23℃ to lower temperatures and the acid amount of its strong acid is 3%more than the physical mixture. So the ZSM-5/β co-crystalline zeolite produces the highest contentof xylene, which is 10.4% higher than the physical mixture. And the ZSM-5/β co-crystalline zeolitehas better selectivity for toluene alkylation and weaker de-methylation than β zeolite, ZSM-5 andtheir physical mixture.展开更多
Recently, it has been shown that plants contain homologs to the animal Polycomb repressive complex I （PRC1） components BM11 and RINGIA/B. In Arabidopsis, there are three BMIl-like genes, two of which, AtBMIIA and B,...Recently, it has been shown that plants contain homologs to the animal Polycomb repressive complex I （PRC1） components BM11 and RINGIA/B. In Arabidopsis, there are three BMIl-like genes, two of which, AtBMIIA and B, are required during post-embryonic plant growth to repress embryonic traits and allow cell differentiation. However, little is known about the third BMIl-like gene, AtBMIIC. In this work, we show that AtBMIIC is only expressed during endosperm and stamen development. AtBMIIC is an imprinted gene expressed from the maternal allele in the endosperm but bialleli- cally expressed in stamen. We found that the characteristic expression pattern of AtBMIIC is the result of a complex epigenetic regulation that involves CG DNA methylation, RNA-directed non-CG DNA methylation （RdDM）, and PcG activity. Our results show the orchestrated interplay of different epigenetic mechanisms in regulating gene expression throughout development, shedding light on the current hypotheses for the origin and mechanism of imprinting in plant endosperm.展开更多
基金We are grateful for the NNSFC (No. 29972017) and the FMEC (No. 98073003).
文摘Two new sesquiterpene lactone glycosides were isolated from the seeds of Carpesium macrocephalum. Their structures were elucidated as 2-O--D-glucopyranosy-5? 11?H- eudesma-4 (15)-en-12, 8?olide and 2 ?O--D-glucopyranosy-5?H-eudesma-4 (15), 11 (13)- dien-12, 8?olide by spectral methods (HRMS, 1 D and 2 D NMR).
文摘ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have beensynthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO_2,silica sol as the source of aluminum and silica, respectively, and TEA^+ as the template undercontrolled condition of the synthesis. The ZSM-5/β co-crystalline zeolite was studied by XRD, SEM,BET and NH_3-TPD. The reaction activity of toluene alkylation was investigated with a mixture oftoluene-methanol as the feedstock in a pulse micro-reactor over the ZSM-5/β co-crystalline zeolite.It is found that ZSM-5/β co-crystalline zeolite has two kinds of zeolite structure including ZSM-5and β zeolite, not in the form of a physical mixture. The pore structure of ZSM-5/βco-crystalline zeolites is different from that for β zeolite, ZSM-5 and their physical mixture. Inaddition, the peaks of both high and low temperature desorption of ammonia over the ZSM-5/βco-crystalline zeolite shift 23℃ to lower temperatures and the acid amount of its strong acid is 3%more than the physical mixture. So the ZSM-5/β co-crystalline zeolite produces the highest contentof xylene, which is 10.4% higher than the physical mixture. And the ZSM-5/β co-crystalline zeolitehas better selectivity for toluene alkylation and weaker de-methylation than β zeolite, ZSM-5 andtheir physical mixture.
文摘Recently, it has been shown that plants contain homologs to the animal Polycomb repressive complex I （PRC1） components BM11 and RINGIA/B. In Arabidopsis, there are three BMIl-like genes, two of which, AtBMIIA and B, are required during post-embryonic plant growth to repress embryonic traits and allow cell differentiation. However, little is known about the third BMIl-like gene, AtBMIIC. In this work, we show that AtBMIIC is only expressed during endosperm and stamen development. AtBMIIC is an imprinted gene expressed from the maternal allele in the endosperm but bialleli- cally expressed in stamen. We found that the characteristic expression pattern of AtBMIIC is the result of a complex epigenetic regulation that involves CG DNA methylation, RNA-directed non-CG DNA methylation （RdDM）, and PcG activity. Our results show the orchestrated interplay of different epigenetic mechanisms in regulating gene expression throughout development, shedding light on the current hypotheses for the origin and mechanism of imprinting in plant endosperm.
