Effects of additional vapors on sterilization of microorganism spores with plasma-excited neutral gas

We investigate the effects of relative humidity on the sterilization process using a plasma-excited neutral gas that uniformly sterilizes both the space and inner wall of the reactor chamber at atmospheric pressure. Only reactive neutral species such as plasma-excited gas molecules and radicals were separated from the plasma and sent to the reactor chamber for chemical sterilization. The plasma source gas is nitrogen mixed with 0.1% oxygen, and the relative humidity in the source gas is controlled by changing the mixing ratio of water vapor. The relative humidity near the sample in the reactor chamber is controlled by changing the sample temperature. As a result, the relative humidity near the sample should be kept in the range from 60 to 90% for the sterilization of Geobacillus stearothermophilus spores. When the relative humidity in the source gas increases from 30 to 90%, the sterilization effect is enhanced by the same degree.

Section: Generating Plasma-excited Neutral Gasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of humidity on sterilization ofGeobacillus stearothermophilusspores with plasma-excited neutral gas

Matsui¹,

Ikenaga²,

Sakudo³

2015

“…perviridis. Furthermore, Matsui et al 10) also suggested that long-lifetime neutral particles in the gas phase, such as O 3 , H 2 O 2 , and HNO 3 , and synergistic effects between these species play a key role in the disinfection of Geobacillus stearothermophilus spores. To utilize the PTW effectively and efficiently, it is important to control the ROS= RNS concentration and to clarify the interaction between species in plasma and ROS=RNS in water as well as to investigate efficacy in the application fields, since PTW with a wide-ranging ROS=RNS concentration is used for the investigation of efficacy.…”

Section: Introductionmentioning

confidence: 99%

Production characteristics of reactive oxygen/nitrogen species in water using atmospheric pressure discharge plasmas

Takahashi

Satoh

Kawaguchi

et al. 2016

A pulsed discharge, a DC corona discharge, and a plasma jet are separately generated above a water surface, and reactive oxygen species and reactive nitrogen species (ROS/RNS) in the water are investigated. ROS/RNS in water after the sparging of the off-gas of a packed-bed dielectric barrier discharge (PB-DBD) are also investigated. H 2 O 2 , NO 2 % , and NO 3 % are detected after plasma exposure and only NO 3 % after off-gas sparging. Short-lifetime species in plasma are found to play an important role in H 2 O 2 and NO 2 % production and long-lifetime species in NO 3 % production. NO x may inhibit H 2 O 2 production through OH consumption to produce HNO 2 and HNO 3. O 3 does not contribute to ROS/RNS production. The pulsed plasma exposure is found to be effective for the production of H 2 O 2 and NO 2 % , and the off-gas sparging of the PB-DBD for the production of NO 3 % .

“…Recently, many studies on plasma applications of agriculture and medicine have been reported. [1][2][3][4][5][6][7][8][9] In particular, effects of plasma irradiation on the germination and growth of plants have been investigated as agricultural applications. It has been reported that effects of plasmas using various gases such as CF 4 , aniline, cyclohexane, helium, and air on the germination and growth enhancement of plants are observed.…”

Section: Introductionmentioning

confidence: 99%

Variation of antioxidative activity and growth enhancement of Brassicaceae induced by low-pressure oxygen plasma

Ono

Hayashi

2015

The mechanism of growth enhancement induced by active oxygen species generated in an oxygen plasma is investigated. The plant growth enhancement induced by the active oxygen species would relate to an antioxidative activity, which is one of the biological responses. The amount of generated active oxygen species is varied by the oxygen gas pressure in a low-pressure RF glow discharge plasma. The antioxidative activity of sprouts of Brassicaceae induced by the oxygen plasma is maximized at pressures between 30 and 40 Pa, whereas the antioxidative activity becomes small at around 60 and 80 Pa. The pressure dependence of the antioxidative activity of sprout stems is opposite to that of the stem length of the sprouts. The growth enhancement would be induced by the increase in the concentration of active oxygen species in plants owing to the decrease in the amount of antioxidative substances.