Directly correlating the morphology and composition of interfacial water is vital not only for studying water icing under critical conditions but also for understanding the role of protein–water interac-tions in bio-...Directly correlating the morphology and composition of interfacial water is vital not only for studying water icing under critical conditions but also for understanding the role of protein–water interac-tions in bio-relevant systems.In this study,we present a model system to study two-dimensional(2D)water layers under ambient conditions by using self-assembled monolayers(SAMs)supporting the physisorp-tion of the Cytochrome C(Cyt C)protein layer.We observed that the 2D island-like water layers were uniformly distributed on the SAMs as characterized by atomic force microscopy,and their composition was confirmed by nano-atomic force microscopy-infrared spectroscopy and Raman spectroscopy.In addition,these 2D flakes could grow under high-humidity conditions or melt upon the introduction of a heat source.The formation of these flakes is attributed to the activation energy for water desorption from the Cyt C being nearly twofold high than that from the SAMs.Our results provide a new and effective method for further understanding the water–protein interactions.展开更多
Surficial water adsorption and interfacial water condensation as natural phenomena play an essential role in the contact adhesion and friction performances of the solid interface. As the characteristic dimensions down...Surficial water adsorption and interfacial water condensation as natural phenomena play an essential role in the contact adhesion and friction performances of the solid interface. As the characteristic dimensions downscale to nanometers, the structure and dynamics of the water film at an interface differ significantly from those of its bulk counterpart. In particular, a specific wetting condition termed as the tacky regime has recently sparked great interest in the community, where transient high friction and contact instabilities are observed at the interface that is subjected to the wet-to-dry transition. Unveiling the influence of nanoscale water film on the friction enhancement in the tacky regime will provide theoretical guidance for the friction regulation in the wetting condition. In this article, special emphasis is placed on the development of experimental techniques which allow the visualization of the contact interface (e.g., contact surface deformation, real contact area) and characterization of water film structures (e.g., film thickness, molecular configuration). Building upon the accumulation of recent research activities, we provide an overview of significant advances in understanding the critical mechanisms for friction enhancement, such as vertical capillary force, interfacial shear strength, and ice-like water. Some common design strategies are further given to regulate the friction behavior by tuning the distribution of the water film, surface roughness, and elastic modulus. Finally, we end this review article with a summary of the research status and outlook on areas for future research directions.展开更多
Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related envir...Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related environment. However, its distribution in other bacteria and potential molecular dissemination mechanism in environment are still unknown. The purpose of this study was to investigate the potential mechanism underlying dissemination of tet(31) by analysing the tet(31)-carrying fragments in A. caviae strains isolated from an aerobic biofilm reactor treating oxytetracycline bearing wastewater. Twenty-three A. caviae strains were screened for the tet(31) gene by polymerase chain reaction(PCR). Three strains(two harbouring tet(31), one not) were subjected to whole genome sequencing using the PacBio RSII platform. Seventeen A. caviae strains carried the tet(31) gene and exhibited high resistance levels to oxytetracycline with minimum inhibitory concentrations(MICs)ranging from 256 to 512 mg/L. tet(31) was comprised of the transposon Tn6432 on the chromosome of A. caviae, and Tn6432 was also found in 15 additional tet(31)-positive A. caviae isolates by PCR. More important, Tn6432 was located on an integrative conjugative element(ICE)-like element, which could mediate the dissemination of the tet(31)-carrying transposon Tn6432 between bacteria. Comparative analysis demonstrated that Tn6432 homologs with the structure ISCR2-ΔphzF-tetR(31)-tet(31)-ΔglmM-sul2 were also carried by A. salmonicida, G. anatis, and O. alkaliphila, suggesting that this transposon can be transferred between species and even genera. This work provides the first report on the identification of the tet(31) gene in A. caviae, and will be helpful in exploring the dissemination mechanisms of tet(31) in water environment.展开更多
基金supported by the National Natural Science Foundation of China(22273045,52488101 and 22472043)Ningbo Youth Science and Technology Innovation Leading Talent(2023QL041)Tsinghua University Independent Scientific Research Plan for Young Investigator,Tsinghua University Dushi Program,and Initiative Scientific Research Program。
文摘Directly correlating the morphology and composition of interfacial water is vital not only for studying water icing under critical conditions but also for understanding the role of protein–water interac-tions in bio-relevant systems.In this study,we present a model system to study two-dimensional(2D)water layers under ambient conditions by using self-assembled monolayers(SAMs)supporting the physisorp-tion of the Cytochrome C(Cyt C)protein layer.We observed that the 2D island-like water layers were uniformly distributed on the SAMs as characterized by atomic force microscopy,and their composition was confirmed by nano-atomic force microscopy-infrared spectroscopy and Raman spectroscopy.In addition,these 2D flakes could grow under high-humidity conditions or melt upon the introduction of a heat source.The formation of these flakes is attributed to the activation energy for water desorption from the Cyt C being nearly twofold high than that from the SAMs.Our results provide a new and effective method for further understanding the water–protein interactions.
基金National Natural Science Foundation of China(Grant Nos.12202430,12241202 and 12402118)the National Key Research and Development Program of China(Grant No.2022YFA1205400)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2090002011).
文摘Surficial water adsorption and interfacial water condensation as natural phenomena play an essential role in the contact adhesion and friction performances of the solid interface. As the characteristic dimensions downscale to nanometers, the structure and dynamics of the water film at an interface differ significantly from those of its bulk counterpart. In particular, a specific wetting condition termed as the tacky regime has recently sparked great interest in the community, where transient high friction and contact instabilities are observed at the interface that is subjected to the wet-to-dry transition. Unveiling the influence of nanoscale water film on the friction enhancement in the tacky regime will provide theoretical guidance for the friction regulation in the wetting condition. In this article, special emphasis is placed on the development of experimental techniques which allow the visualization of the contact interface (e.g., contact surface deformation, real contact area) and characterization of water film structures (e.g., film thickness, molecular configuration). Building upon the accumulation of recent research activities, we provide an overview of significant advances in understanding the critical mechanisms for friction enhancement, such as vertical capillary force, interfacial shear strength, and ice-like water. Some common design strategies are further given to regulate the friction behavior by tuning the distribution of the water film, surface roughness, and elastic modulus. Finally, we end this review article with a summary of the research status and outlook on areas for future research directions.
基金supported by the National Natural Scientific Foundation of China (No.21437005)
文摘Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related environment. However, its distribution in other bacteria and potential molecular dissemination mechanism in environment are still unknown. The purpose of this study was to investigate the potential mechanism underlying dissemination of tet(31) by analysing the tet(31)-carrying fragments in A. caviae strains isolated from an aerobic biofilm reactor treating oxytetracycline bearing wastewater. Twenty-three A. caviae strains were screened for the tet(31) gene by polymerase chain reaction(PCR). Three strains(two harbouring tet(31), one not) were subjected to whole genome sequencing using the PacBio RSII platform. Seventeen A. caviae strains carried the tet(31) gene and exhibited high resistance levels to oxytetracycline with minimum inhibitory concentrations(MICs)ranging from 256 to 512 mg/L. tet(31) was comprised of the transposon Tn6432 on the chromosome of A. caviae, and Tn6432 was also found in 15 additional tet(31)-positive A. caviae isolates by PCR. More important, Tn6432 was located on an integrative conjugative element(ICE)-like element, which could mediate the dissemination of the tet(31)-carrying transposon Tn6432 between bacteria. Comparative analysis demonstrated that Tn6432 homologs with the structure ISCR2-ΔphzF-tetR(31)-tet(31)-ΔglmM-sul2 were also carried by A. salmonicida, G. anatis, and O. alkaliphila, suggesting that this transposon can be transferred between species and even genera. This work provides the first report on the identification of the tet(31) gene in A. caviae, and will be helpful in exploring the dissemination mechanisms of tet(31) in water environment.
