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应用超临界流体萃取改善煤沥青的炭化性质
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作者 masahiro shishido Syuji Yamada +2 位作者 Munio Arai Shozaburo Saito 袁经琏 《炭素技术》 CAS CSCD 1991年第3期23-28,共6页
通过超临界流体(SCF)萃取,改善了煤沥青的炭化性质。经超临界甲苯萃取过的沥青(SCFE沥青)丝毫不含导致小单元尺寸各向异性结构的喹啉不溶物(QI)。由SCFE沥青产生的各向异性结构的尺寸与β—树脂(甲苯不溶—喹啉可溶物)含量密切相关。用... 通过超临界流体(SCF)萃取,改善了煤沥青的炭化性质。经超临界甲苯萃取过的沥青(SCFE沥青)丝毫不含导致小单元尺寸各向异性结构的喹啉不溶物(QI)。由SCFE沥青产生的各向异性结构的尺寸与β—树脂(甲苯不溶—喹啉可溶物)含量密切相关。用搀混方法制取的沥青,使含有的β—树脂含量与SCFE沥青相同(经用常规溶剂萃取得到的甲苯可溶物(TS)和β—树脂搀混而得)比较,搀混沥青的各向异性结构较小。可以用溶解在萃取相一定量的TS溶解量来解释超临界甲苯萃取β—树脂的过程。萃取相中TS浓度高,则溶于该相中的β-树脂溶解度也高。减小萃余液相中TS的浓度,会引起不利于中间相结构发展的较重的β-树脂聚集,并形成不可萃取的QI。由于萃取相和萃余相中TS的浓度取决于萃取压力和超临界甲苯的量与沥青的量之比,因此,调节这两个参数就能控制SCFE沥青中β-树脂的含量。 展开更多
关键词 超临界流体 萃取 沥青 炭化
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Mitigating Root Knot Nematode Propagation on Transgenic Tobacco via <i>in Planta</i>Hairpin RNA Expression of <i>Meloidogyne incognita</i>—Specific PolA1 Sequence
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作者 Peter Nkachukwu Chukwurah Samuel Aduse Poku +3 位作者 Akira Yokoyama Ai Takeda masahiro shishido Ikuo Nakamura 《American Journal of Plant Sciences》 2019年第5期866-884,共19页
Root knot nematodes are top priority nematode pests that significantly constrain agricultural productivity globally especially in developing countries. However, expressing double stranded RNA (dsRNA) of essential nema... Root knot nematodes are top priority nematode pests that significantly constrain agricultural productivity globally especially in developing countries. However, expressing double stranded RNA (dsRNA) of essential nematode genes in susceptible plants is known to confer protection against these pests via RNA silencing. This molecular-based strategy is called host induced gene silencing (HIGS) and the selection of appropriate target nematode gene is critical to its success. In this study, therefore, we focused on root knot nematode PolA1, an essential single copy nuclear gene encoding the largest subunit of RNA polymerase I enzyme and evaluated its effectiveness as a target in conferring nematode resistance on Agrobacterium-mediated transformed tobacco plants. Transgenic tobacco expressing Meloidogyne incognita-specific (MiS) dsRNA of PolA1 gene showed significant reduction in nematode fecundity and multiplication compared to wild type plants in both T0 and T1 generations. T0 plants showed varying degrees of agronomic vigorover WT plants possibly due to varying levels of processed siRNA. However, production of MiS siRNAs in the transgenic plants coupled with significant reduction of PolA1 transcript expression in nematodes feeding on roots of transgenic plants provided evidence of HIGS. Taken together, our results show that PolA1 is a potentially effective target for HIGS-mediated reduction of root knot nematode damage on transgenic tobacco. Given the homology of our target sequence among Meloidogyne species, this protection could be broad range against other root knot nematodes aside M. incognita. 展开更多
关键词 M. incognita NEMATODE Resistance N. tabacum RNA Silencing PolA1 Gene
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