The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that wh...The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that when the tool has a fine and uniform microstructure,the main failure mode is wear failure.Furthermore,observed phenomena including large chip bonding,coating peeling,cracks demonstrate that the main wear mechanisms of the tool are adhesive wear,abrasive wear,coating flaking,and microchipping.展开更多
沙门氏菌是全球范围内危害公众健康的主要食源性致病菌,每年造成千万人食物中毒。黏附于食品加工接触面的生物菌膜是沙门氏菌交叉污染的源头,其对消毒剂具有极强的耐受抵抗作用,可引发大规模食物中毒并导致食品召回。本文在论述细菌黏...沙门氏菌是全球范围内危害公众健康的主要食源性致病菌,每年造成千万人食物中毒。黏附于食品加工接触面的生物菌膜是沙门氏菌交叉污染的源头,其对消毒剂具有极强的耐受抵抗作用,可引发大规模食物中毒并导致食品召回。本文在论述细菌黏附辅助体(菌毛和鞭毛)和胞外多聚物对生物菌膜的具体作用及其在mRNA转录层面调控效应的基础上,重点阐述了转录后层面上的非编码小RNA(non-coding small RNA,sRNA)及其对移动性、胞外多聚物等核心mRNA通路的调控机制,并归纳出sRNA调控生物菌膜的4种作用模式,最后对该领域的研究前景进行了前瞻性展望,以期为拓展研究思路、完善生物菌膜的科学理论和研发针对性控制技术提供参考。展开更多
文摘The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that when the tool has a fine and uniform microstructure,the main failure mode is wear failure.Furthermore,observed phenomena including large chip bonding,coating peeling,cracks demonstrate that the main wear mechanisms of the tool are adhesive wear,abrasive wear,coating flaking,and microchipping.
文摘沙门氏菌是全球范围内危害公众健康的主要食源性致病菌,每年造成千万人食物中毒。黏附于食品加工接触面的生物菌膜是沙门氏菌交叉污染的源头,其对消毒剂具有极强的耐受抵抗作用,可引发大规模食物中毒并导致食品召回。本文在论述细菌黏附辅助体(菌毛和鞭毛)和胞外多聚物对生物菌膜的具体作用及其在mRNA转录层面调控效应的基础上,重点阐述了转录后层面上的非编码小RNA(non-coding small RNA,sRNA)及其对移动性、胞外多聚物等核心mRNA通路的调控机制,并归纳出sRNA调控生物菌膜的4种作用模式,最后对该领域的研究前景进行了前瞻性展望,以期为拓展研究思路、完善生物菌膜的科学理论和研发针对性控制技术提供参考。
