The wettability of the solid surface is often characterized by the contact angle of the liquid on the solid surface. However, it has long been found that the contact angle of liquid on a solid surface can take a range...The wettability of the solid surface is often characterized by the contact angle of the liquid on the solid surface. However, it has long been found that the contact angle of liquid on a solid surface can take a range of values between two extremes： the advancing and the receding contact angles. The difference between the advancing and the receding contact angles is conventionally called contact angle hysteresis. Knowledge of contact angle hysteresis is essential to understand surface wettability and control surface wetting behavior. The wettability can be affected, for example, by the roughness of the solid surface. In our work, textile is used as macroscopic roughness surfaces, and smooth plate surface is used as well to determine contact angle hysteresis. The advancing and receding contact angles are measured on polyamide materials.展开更多
The motion of small bacteria consists of two phases:relatively long runs alternate with intermittent stops,back-ups,or tumbles,depending on the species.In polar monotrichous bacteria,the flagellum is anchored at the c...The motion of small bacteria consists of two phases:relatively long runs alternate with intermittent stops,back-ups,or tumbles,depending on the species.In polar monotrichous bacteria,the flagellum is anchored at the cell pole inherited from the parent generation(old pole) and is surrounded by a chemoreceptor cluster.During forward swimming,the leading pole is always the pole recently formed in cell division(new pole).The flagella of the peritrichous bacterium Escherichia coli often form a bundle behind the old pole.Its cell orientation and receptor positioning during runs generally mimic that of monotrichous bacteria.When encountering a solid surface,peritrichous bacteria exhibit a circular motion with the leading pole dipping downward.Some polar monotrichous bacteria also perform circular motion near solid boundaries,but during back-ups.In this case,the leading pole points upward.Very little is known about behavior near milieu-air interfaces.Biophysical simulations have revealed some of the mechanisms underlying these phenomena,but leave many questions unanswered.Combining biophysics with molecular techniques will certainly advance our understanding of bacterial locomotion.展开更多
文摘The wettability of the solid surface is often characterized by the contact angle of the liquid on the solid surface. However, it has long been found that the contact angle of liquid on a solid surface can take a range of values between two extremes： the advancing and the receding contact angles. The difference between the advancing and the receding contact angles is conventionally called contact angle hysteresis. Knowledge of contact angle hysteresis is essential to understand surface wettability and control surface wetting behavior. The wettability can be affected, for example, by the roughness of the solid surface. In our work, textile is used as macroscopic roughness surfaces, and smooth plate surface is used as well to determine contact angle hysteresis. The advancing and receding contact angles are measured on polyamide materials.
文摘The motion of small bacteria consists of two phases:relatively long runs alternate with intermittent stops,back-ups,or tumbles,depending on the species.In polar monotrichous bacteria,the flagellum is anchored at the cell pole inherited from the parent generation(old pole) and is surrounded by a chemoreceptor cluster.During forward swimming,the leading pole is always the pole recently formed in cell division(new pole).The flagella of the peritrichous bacterium Escherichia coli often form a bundle behind the old pole.Its cell orientation and receptor positioning during runs generally mimic that of monotrichous bacteria.When encountering a solid surface,peritrichous bacteria exhibit a circular motion with the leading pole dipping downward.Some polar monotrichous bacteria also perform circular motion near solid boundaries,but during back-ups.In this case,the leading pole points upward.Very little is known about behavior near milieu-air interfaces.Biophysical simulations have revealed some of the mechanisms underlying these phenomena,but leave many questions unanswered.Combining biophysics with molecular techniques will certainly advance our understanding of bacterial locomotion.
