The effect of the configuration of a single electrode corona discharge on its acoustic characteristics

A new sparker system based on pulsed spark discharge with a single electrode has already been utilized for oceanic seismic exploration. However, the electro-acoustic energy efficiency of this system is lower than that of arc discharge based systems. A simple electrode structure was investigated in order to improve the electro-acoustic energy efficiency of the spark discharge. Experiments were carried out on an experimental setup with discharge in water driven by a pulsed power source. The voltage-current waveform, acoustic signal and bubble oscillation were recorded when the relative position of the electrode varied. The electro-acoustic energy , efficiency was also calculated. The load voltage had a saltation for the invaginated electrode tip, namely an obvious voltage remnant. The more the electrode tip was invaginated, the larger the pressure peaks and first period became. The results show that electrode recessing into the insulating layer is a simple and effective way to improve the electro-acoustic energy efficiency from 2% to about 4%.

Experimental study on bacteria disinfection using a pulsed cold plasma jet with helium/ oxygen mixed gas

Cold atmospheric plasma jet is widely used in many fields due to the reactive oxygen species and low temperature for heat-sensitive products. This paper presents the inactivation of bacteria via a pulsed plasma jet with He/O2 mixed gas. To evaluate the disinfection performance, Staphylococcus aureus was used as an indicator bacteria for experiments. When the plasma jet dealt with agar plates spraying bacteria, it was found that mixed gas has a better performance than pure inert gas, indicated by the disinfection area. The increment of oxygen gas addition was beneficial to the disinfection ability of the plasma jet, while the gas had an opposite effect on the length of jet production. The experiments showed the efficacy of Staphylococcus aureus disinfection could reach up to 99.47% via a helium/oxygen （2%） plasma jet.

Unraveling the evolution of oxygen vacancies in TiO_(2–x)/Cu and its role in CO_(2)hydrogenation

The remarkable contribution of oxygen vacancies has been revealed by the operando spectroscopies for methanol synthesis from CO_(2)hydrogeneration on the reducible metal oxide-supported copper catalysts.However,a challenge remains in the intrinsic understanding of the evolution and advantage of oxygen vacancies for methanol synthesis.Here we prepare the TiO_(2–x)/Cu with different oxygen vacancy densities by adjusting the ball-milling frequency.At the optimal condition,a TiO_(2–x)/Cu with more oxygen vacancies delivers an excellent methanol yield of 26.5 mmol g^(-1)h^(-1)at 300℃with a selectivity of more than 70%.The combined analysis of experimental characterizations and theoretical calculations reveals that the mutual dispersions of TiO_(2–x)and Cu driven by mechanical energy induce the electron rearrangement in the d orbital of the Ti atom and relax the Ti–O binding at the interface,which facilitates the formation of oxygen vacancies that further reduce the barrier of CO_(2)hydrogenation to^(*)HCOO due to higher nucleophilicity of titanium ions.