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procedures is almost the same as its counterpart strain of Bacillus atrophaeus for- merly subtilis #AT CC 9372. Somedifferences have been observed recently among which the pigment which appears only to the last one [118]. Moreover, Bacillus atrophaeus is also known to produce a taxonomic confusion as a consequence of its reclassification. It is not the case of the strain of Bacillus subtilis #AT CC 6633. Therefore, we choose to maintain the same sporulated form and its scien- tific nameastestingmicroorganismsthroughout the microbiological experimental procedure. 2.3.2.2 Samples preparation Avolumeof100 µl of sterile water containing a spore population of N0 =10 6 was aseptically spread (by dropping) on the surface of a glass slide (25 × 15 mm 2 ) and allowed to dry overnight. In order to avoid the spore stacking, the initial volume of 100 µl wasdividedin5 aliquots of 20 µl, dropping them in 5 different points on the glass slide. For all the obtained samples, the covering degree of the glass slide surface was higher than 75% (i.e., α>0.75, whereα is the fraction of the wetted glass slide surface). Under these conditions the effective contaminated area of the glass slide is Aeff = αA > 281.25 mm 2 , A =375mm 2 being the surface of the glass slide. Consequently, the mean number of spores per effective contaminated area is n0 = N0/Aeff < 3.56 × 10 −3 µm −2 , which means that, on average, each spore 33
has n −1 0 > 281.25 µm 2 available surface on the glass slide. Taking into account that the mean surface occupied by an untreated spore is A0 ≈ 0.75 µm 2 ,then each spore has an average available surface on the glass slide (n0A0) −1 > 375 times higher than its own [57]. This means that the spreading method used in the present experiments avoids stacking (i.e., the spores form a monolayer on the surface of the glass slide). 2.3.2.3 Determination of viable spores After the plasma treatment, the glass slide with the microbiological material on it was aseptically recovered and washed in 10 ml of sterile water in a glass test tube. The content of the glass test tube was gently shaken, and then ultrasonicated at 39.5 kHz for 3 minutes. One ml of this volume was diluted by adding 9 ml of sterile water. This procedure was repeated until the desired dilution factor was achieved. In order to decrease the detection limit of the counting method less than 1 log, a volume of 2 ml of each dilution was transferred and equally plated on 2 Petrifilms TM (3M Company). Indeed, if from 10 ml dilution containing 10 spores, only 1 ml is plated on a Petrifilm and no colony is detected, the detection limit will certainly be 1 log (i.e., 10 spores). However, from these 10 ml of dilution containing 10 spores, we extracted 2 ml and equally plated them on two Petrifilms. Under these circumstances, the detection limit decreases under 5 spores (which is less 34
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 and 40: ment time t is N = N0e −αt ≡ N
Page 41: shows the number of the viable micr
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
Page 93 and 94:
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
Page 101 and 102:
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
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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
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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
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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