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Contact characteristics and interfacial motion states during sphere oblique impact with initial spin
Qingpeng Wang,Kai Zhang,Zhenfeng Wang,Heng Wang,Yufeng Sun,Xiankun Gao,Guangyin Xu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5
The impact between a sphere and flat surface plays a significant role in the granular handling process. A method is proposed to investigate the evolution of interfacial states for the sphere oblique impact with initial spin. Firstly, the sphere with irregular surface structures is applied, and the imprinted surfaces are recorded with a thin carbon paper. Then the interfacial characteristics are analyzed in cases of impact angle, contact material and drop height, etc. The geometrical parameters decrease exponentially with impact angle and include three main stages: plateau, slow decrease and sharp decrease. The motional ratio corresponds to slow increase, steady state and sharp increase. For the no pre-spin, it goes through five interfacial states with impact angle. Comparatively, the forward spin decreases the critical angle, and the backward spin decreases the number of states. Furthermore, the parameters increase linearly with drop height, while the effect on interfacial states is very little.
( Zhenyue Feng ),( Defu Liu ),( Ziwen Liu ),( Yimin Liang ),( Yanhong Wang ),( Qingpeng Liu ),( Zhenhua Liu ),( Zhongjing Zang ),( Yudong Cui ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.7
A putative multidrug efflux gene, yddA, was cloned from the Escherichia coli K-12 strain. A drugsensitive strain of E. coli missing the main multidrug efflux pump AcrB was constructed as a host and the yddA gene was knocked out in wild-type (WT) and drug-sensitive E. coliΔacrB to study the yddA function. Sensitivity to different substrates of WT E.coli, E. coliΔyddA, E. coliΔacrB and E. coliΔacrBΔyddA strains was compared with minimal inhibitory concentration (MIC) assays and fluorescence tests. MIC assay and fluorescence test results showed that YddA protein was a multidrug efflux pump that exported multiple substrates. Three inhibitors, ortho-vanadate, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and reserpine, were used in fluorescence tests. Ortho-vanadate and reserpine significantly inhibited the efflux and increased accumulation of ethidium bromide and norfloxacin, while CCCP had no significant effect on YddA-regulated efflux. The results indicated that YddA relies on energy released from ATP hydrolysis to transfer the substrates and YddA is an ABC-type multidrug exporter. Functional study of unknown ATP-binding cassette (ABC) superfamily transporters in the model organism E. coli is conducive to discovering new multidrug resistance-reversal targets and providing references for studying other ABC proteins of unknown function.