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N/N 0 1.0 0.8 0.6 0.4 0.2 0.0 0 2 4 6 8 10 t (min) inactivation curve survival curve Figure 2.4: Time evolution of inactivated or survival bacteria during the inactivation process. k = nX ki. (2.10) i=1 Consequently, the global D-value can be written as: 1 D = nX i=1 1 Di . (2.11) Usually, to quantify the destruction effects of an inactivation agent, survival or inactivation curves of the microorganism population is used [117, 118]. These are drawn both in Fig. 2.4. The survival curve (represented by continuous line) 31
shows the number of the viable microorganisms at the end of the treatment. The inactivation curve (represented by dashed line) shows the number of the inactivated microorganisms at the end of the treatment time. The survival/inactivation ratio is used to study the influence of the inactivation agents on microorganisms viability (i.e., the relative number N/N0 or 1 − N/N0 of the surviving/inactivated bacteria at the end of the treatment period). 2.3.2 Experimental technique used for bacteria inactivation 2.3.2.1 Microorganisms used for testing procedures The microorganisms used in all the experiments were sporulated form of Bacil- lus Subtilis (American Type Culture Collection #6633), due to the fact that the spores present a higher resistance to inactivation when are exposed to extreme environment conditions than microorganisms in vegetative state [25, 117, 118]. With other words, if the experimental procedure is suitable for sporulated form inactivation or sterilization, it will certainly give successful results for the same bacterium, but in the vegetative state. Since a spore is a “dormant” bacterium (i.e., a resistant and defensive form of bacteria to harsh environments), the use of spore contaminated samples for plasma sterilization testing procedures is encouraged. Regarding the taxonomy of Bacillus subtilis species, it can be stressed that phenotipically, Bacillus subtilis #AT CC 6633 which is widely used in sterilization 32
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 and 14: Figure 1.1: Schematic representatio
Page 15 and 16: Table 1.1: Common disinfection and
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: ment time t is N = N0e −αt ≡ N
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
Page 65 and 66: D (min) 10 3 10 2 10 1 10 0 Dν D h
Page 67 and 68: N/N 0 (%) 10 2 10 2 10 2 10 2 10 2
Page 69 and 70: D (min) 10 2 10 1 10 0 D h+ν+p D h
Page 71 and 72: holder is mainly given by particle
Page 73 and 74: 3.5 Power sensitivity of spore inac
Page 75 and 76: If for a reference treatment temper
Page 77 and 78: of the sample was achieved. Moreove
Page 79 and 80: microorganisms were disposed in mon
Page 81 and 82: The pulse period covered a wide int
Page 83 and 84: in chapter 2. The treatment time of
Page 85 and 86: 4.2.2 Injected RF power In order to
Page 87 and 88: ton =500µs, and the duty cycle was
Page 89 and 90: T ( 0 C) 120 100 80 60 40 20 I 0 5
Page 91 and 92:
N/N 0 (%) 10 2 10 2 10 2 10 1 10 1
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elow 70 ◦ C. 3. Increasing the in
Page 95 and 96:
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
Page 109 and 110:
value. When ton has been kept const
Page 111 and 112:
survival curve characteristics were
Page 113 and 114:
of the effects produced by differen
Page 115 and 116:
solutely necessary for a profound u
Page 117 and 118:
Conferences 1. Bacillus spores ster
Page 119 and 120:
[9] W. A. Rutala, D. J. Weber, J. H
Page 121 and 122:
[34] J. H. Young: Sterilization wit
Page 123 and 124:
[57] M. K. Boudam, M. Moisan, B. Sa
Page 125 and 126:
[79] J. Schneider, K. M. Baumgartne
Page 127 and 128:
[100] S. Villeger, S. Cousty, A. Ri
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