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Germination Spore coat Sporulation Vegetative cell Spore coat formation Figure 1.2: Illustration of the main phases of the sporulation-germination cycle. After [27]. survival. When the life conditions allow the sporulated form germinate back into vegetative cell again through the enzimatically triggered germinative processes. Usually, the sporulated forms are recognized as very hard to kill microorganisms. Their resistance is due to the protection systems developed during the sporulation process [23, 25, 26]. 1.2 Disinfection and sterilization methods The decontamination (i.e., disinfection or sterilization) methods can be di- vided by the type of the killing agent used in the treatment procedures. When the inactivation agent come into direct contact with the contaminants, the suc- 5
Table 1.1: Common disinfection and sterilization methods. Sterilization Method The killing agent Thermal method pressured steam heat, dry heat Electromagnetic radiation Chemical method ultraviolet photons, gamma rays, X rays, microwaves, electric fields ethylene oxide gas, formaldehyde gas, ozone, glutaraldehyde, peracetic acid, chlorine dioxide, hydrogen peroxide, high pressure carbon dioxide Particle bombardment method particle beams (E-beams, ion and neutral beams) Plasma method heat, optical radiation, plasma particles cess of the procedures depends in principal on two important factors: the type of the microorganisms and the nature of the killing agents [8]. A summary of these techniques used in daily medical practice is presented in Table 1.1. 1.2.1 Sterilization by heat Heat is the physical agent mostly used for sterilization and disinfection in moist and dry heat forms [8, 25, 28, 29]. An additional technique to the existing ones is the pyrolysis [30]. The effectiveness of these methods depends on the 6
Page 1 and 2: PLASMA STERILIZATION USING LOW PRES
Page 3 and 4: my appreciation especially for the
Page 5 and 6: Iis ion saturation current [µA] t
Page 7 and 8: CONTENTS 1 PRINCIPLES OF SURFACE DI
Page 9 and 10: 4 EFFECTS OF LOW TEMPERATURE PULSED
Page 11 and 12: and intuited to bring new important
Page 13: Figure 1.1: Schematic representatio
Page 17 and 18: the radiation energy is resonantly
Page 19 and 20: ers of heat, optical radiation and
Page 21 and 22: Table 1.2: Main plasma sources used
Page 23 and 24: microorganism population as a respo
Page 25 and 26: UV Photon Before After DNA Figure 1
Page 27 and 28: to sterilize medical tools, but the
Page 29 and 30: sented by both theoretical and expe
Page 31 and 32: Plasma Sterilization Using Low Pres
Page 33 and 34: Figure 2.1: Experimental set-up. MB
Page 35 and 36: Figure 2.3: Electronic circuit of t
Page 37 and 38: such circumstances, the inactivatio
Page 39 and 40: ment time t is N = N0e −αt ≡ N
Page 41 and 42: shows the number of the viable micr
Page 43 and 44: has n −1 0 > 281.25 µm 2 availab
Page 45 and 46: 1 st 2 nd ( I) TNTC (II) TNTC (III)
Page 47 and 48: U LC blocking filter 19.74 pF 20.24
Page 49 and 50: Figure 2.8: Experimental set-up use
Page 51 and 52: the reactive species from plasma ar
Page 53 and 54: Temperature measurement Relative in
Page 55 and 56: MR MP SH Figure 3.2: Experimental a
Page 57 and 58: a fast temperature increasing rate.
Page 59 and 60: D h (min) 10 3 10 2 10 1 10 0 100 2
Page 61 and 62: MR QP SH Figure 3.6: Experimental a
Page 63 and 64: The contribution of photons and hea
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D (min) 10 3 10 2 10 1 10 0 Dν D h
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N/N 0 (%) 10 2 10 2 10 2 10 2 10 2
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D (min) 10 2 10 1 10 0 D h+ν+p D h
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holder is mainly given by particle
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3.5 Power sensitivity of spore inac
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If for a reference treatment temper
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of the sample was achieved. Moreove
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microorganisms were disposed in mon
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The pulse period covered a wide int
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in chapter 2. The treatment time of
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4.2.2 Injected RF power In order to
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ton =500µs, and the duty cycle was
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T ( 0 C) 120 100 80 60 40 20 I 0 5
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N/N 0 (%) 10 2 10 2 10 2 10 1 10 1
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elow 70 ◦ C. 3. Increasing the in
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the second phase of the inactivatio
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k 1, 2 (min -1 ) 1.2 1.0 0.8 0.6 0.
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I (arb. unit) 140 120 100 80 60 40
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I (arb. unit) 5 4 3 2 1 0 0.000 0.0
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I > (arb.unit) 1.0 0.9 0.8 0.7 0.6
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shown in Fig. 4.14. It can be seen
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I is (mA) 0.25 0.20 0.15 0.10 0.05
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value. When ton has been kept const
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survival curve characteristics were
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of the effects produced by differen
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solutely necessary for a profound u
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Conferences 1. Bacillus spores ster
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[9] W. A. Rutala, D. J. Weber, J. H
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[34] J. H. Young: Sterilization wit
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[57] M. K. Boudam, M. Moisan, B. Sa
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[79] J. Schneider, K. M. Baumgartne
Page 127 and 128:
[100] S. Villeger, S. Cousty, A. Ri
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