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温度和纱线捻向对自润滑织物复合材料摩擦磨损性能的影响 被引量:5
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作者 苏萌 任放 +4 位作者 俞鸣明 任幕苏 孙晋良 梁磊 姚卫刚 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2019年第9期82-88,94,共8页
分别将S捻和Z捻PTFE-Nomex/Nomex织物与高温树脂复合,制得S捻和Z捻PTFE-Nomex/Nomex织物复合材料。通过评价不同温度时复合材料的摩擦磨损性能,研究了纤维加捻方式对复合材料摩擦磨损性能的影响。研究结果表明,S捻PTFE-Nomex/Nomex织物... 分别将S捻和Z捻PTFE-Nomex/Nomex织物与高温树脂复合,制得S捻和Z捻PTFE-Nomex/Nomex织物复合材料。通过评价不同温度时复合材料的摩擦磨损性能,研究了纤维加捻方式对复合材料摩擦磨损性能的影响。研究结果表明,S捻PTFE-Nomex/Nomex织物力学性能略优,2种织物的拉伸强度均高于25 MPa,断裂伸长率均大于75%;S捻PTFE-Nomex/Nomex织物复合材料磨损量受温度影响较小,而Z捻PTFE-Nomex/Nomex织物复合材料磨损量随温度的升高而增大,在相同温度时,前者的磨损量小于后者;2种材料的摩擦系数受温度影响不大,且相同温度时S捻PTFE-Nomex/Nomex织物复合材料的摩擦系数较小。磨损机理分析表明,温度对材料磨损状态具有显著影响,且织物力学性能的提高和磨损表面更连续、完整的润滑膜使S捻PTFE-Nomex/Nomex织物复合材料具有更好的摩擦磨损性能。 展开更多
关键词 纤维 加捻 聚四氟乙烯 芳纶 温度 摩擦磨损性能
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Improvement of oxytetracycline production mediated via cooperation of resistance genes in Streptomyces rimosus 被引量:11
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作者 Shouliang Yin Xuefeng Wang +10 位作者 Mingxin Shi Fang Yuan Huizhuan Wang Xiaole Jia Fang Yuan jinliang sun Tiejun Liu Keqian Yang Yuxiu Zhang Keqiang Fan Zilong Li 《Science China(Life Sciences)》 SCIE CAS CSCD 2017年第9期992-999,共8页
Increasing the self-resistance levels of Streptomyces is an effective strategy to improve the production of antibiotics.To increase the oxytetracycline(OTC) production in Streptomyces rimosus,we investigated the coope... Increasing the self-resistance levels of Streptomyces is an effective strategy to improve the production of antibiotics.To increase the oxytetracycline(OTC) production in Streptomyces rimosus,we investigated the cooperative effect of three co-overexpressing OTC resistance genes:one gene encodes a ribosomal protection protein(otrA) and the other two express efflux proteins(otrB and otrC).Results indicated that combinational overexpression of otrA,otrB,and otrC(MKABC) exerted a synergetic effect.OTC production increased by 179%in the recombinant strain compared with that of the wild-type strain M4018.The resistance level to OTC was increased by approximately two-fold relative to the parental strain,thereby indicating that applying the cooperative effect of self-resistance genes is useful to improve OTC production.Furthermore,the previously identified cluster-situated activator OtcR was overexpressed in MKABC in constructing the recombinant strain MKRABC;such strain can produce OTC of approximately7.49 g L^((-1)),which represents an increase of 19%in comparison with that of the OtcR-overexpressing strain alone.Our work showed that the cooperative overexpression of self-resistance genes is a promising strategy to enhance the antibiotics production in Streptomyces. 展开更多
关键词 resistance genes OXYTETRACYCLINE combinatorial overexpression cluster-situated activator Streptomyces rimosus
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