title: Investigation of a sterilization system using active oxygen species generated by ultraviolet irradiation.
abstract: We have been investigating an advanced sterilization system that employs active oxygen species (AOS). We designed the sterilization equipment, including an evacuation system, which generates AOS from pure oxygen gas using ultraviolet irradiation, in order to study the conditions necessary for sterilization in the system's chamber. Using Geobachillus stearothermophilus spores (10(6) CFU) in a sterile bag as a biological indicator (BI) in the chamber of the AOS sterilization apparatus, we examined the viability of the BI as a function of exposure time, assessing the role of the decompression level in the sterilization performance. We found that the survival curves showed exponential reduction, and that the decompression level did not exert a significant influence on the survival curve. Subsequently, we investigated the sterilization effect as influenced by the spatial and environmental temperature variation throughout the chamber, and found that the sterilization effect varied with position, due to the varying environmental temperature in the respective areas. We confirmed that temperature is one of the most important factors influencing sterilization in the chamber, and estimated the temperature effect on the distribution of atomic oxygen concentration, using the quartz crystal microbalance (QCM) method with fluorocarbon thin film prepared by radio frequency sputtering.
authors.affiliation: Research and Development Department, Iwasaki Electric Co., Ltd., 1-1 lchiryma-chou, Gyoda, Saitama 361-8505; 2. Faculty of Engineering, Tokai University Kanagawa, 4-1-1 Kitakaname, Hirastuka City, Kanagawa 259-1292, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yoshino
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Shinobu
authors.initials: S
authors.lastname: Kinoshita
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Noda
authors.forename: Kei
authors.initials: K
authors.lastname: Oya
authors.forename: Satoru
authors.initials: S
authors.lastname: Iwamori
mesh_terms: D001411:Geobacillus stearothermophilus / Q000187:drug effects; D050296:Microbial Viability / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000633:toxicity*; D013171:Spores, Bacterial / Q000187:drug effects; D013242:Sterilization / Q000295:instrumentation* / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014466:Ultraviolet Rays; D014618:Vacuum
chemical_list: D017382:Reactive Oxygen Species