RESUMO
The utilization of water energy through the Single Electrode Droplet-Based Electricity Generator (SE-DEG) represents a universal and high-efficiency method for water energy harvesting. Previous research has extensively elucidated the working principle of SE-DEG based on bulk effect. However, scant attention has been paid to the investigation of the electrical characteristics surrounding the SE-DEG. Remarkably, the electrical characteristics around the SE-DEG can be exploited to generate electricity and harvest corresponding energy. Here we evaluate the electrical characteristics around the SE-DEG by arranging extra electrodes. An interesting phenomenon is found that, on the premise of no contact between extra electrodes and the droplet, there is opposite electricity output from extra electrodes synchronously when the droplet contacts on the PTFE film and SE-DEG electrode and outputs the electricity. This phenomenon is comprehensively explained and verified from working mechanism, the impacts of different arrangements and the array design of extra electrodes. Significantly, utilizing the electrical characteristics could harvest additional kinetic energy with extra electrodes in SE-DEG. This investigation is expected to provide new insights into the future harnessing of water kinetic energy within the SE-DEG framework.
RESUMO
The persistence of Escherichia coli O157:H7 in soil is one of the most common causes of the food-borne outbreaks. Nano-sized iron oxide minerals in soil, especially goethite, have been found to reduce bacterial viability, which helps to control the spread of human pathogens. However, little is known about the antibacterial effects of iron oxides with different particle sizes. Our result revealed that the micro-sized goethite exhibited a more effective antibacterial activity against E. coli O157:H7 than the nano-sized goethite. The underlying antibacterial mechanisms were further investigated via single-cell Raman microspectroscopy. The exposure to nano-sized goethite increased the levels of ribonucleoside-related substances, phenylalanine and adenosine 5'-triphosphate, while decreased those of glycogen, protein and lipopolysaccharide & outer membrane porins (LPS & OMPs). Meanwhile, micro-sized goethite triggered less variation in ribonucleoside-related substances and induced more reduction in LPS & OMPs. Therefore, the antibacterial effects of nano-sized goethite were mediated by both ROS-dependent RNA damage and cell membrane destruction, whereas micro-sized goethite induced severer membrane damage and less ROS-dependent oxidative stress. This work demonstrates the role of particle sizes in antibacterial effects of iron oxides and provides implications for the pathogen control in soil.