Revealing the infiltration process and retention mechanisms of surface applied free DNA tracer through soil under flood irrigation.

It has been recently demonstrated that free DNA tracers have the potential in tracing water flow and contaminant transport through the vadose zone. However, whether the free DNA tracer can be used in flood irrigation area to track water flow and solute/contaminant transport is still unclear. To reveal the infiltration process and retention mechanisms of surface applied free DNA tracer through soil under flood irrigation, we tested the fate and transport behavior of surface applied free DNA tracers through packed saturated sandy soil columns with a 10 cm water head mimicking flood irrigation.

[Effect of continuous flushing out of root canal on fluid replacement in root canal during mechanical preparation using Ni-Ti instrument].

Purpose: To evaluate the effect of continuous flushing out of the canal on fluid exchange in the root canal during mechanical preparation.

Methods: Sixty resin blocks with standardized root canals were divided into 5 experimental groups according to whether continuous flushing was performed during mechanical preparation. Injecting pure black ink into the root canals before each file preparation，the liquid exchange was calculated by measuring the absorbance value of the remaining liquid after performing different preparation and irrigation schemes.