Proceedings e report - Firenze University Press

WOOD SCIENCE FOR CONSERVATION OF CULTURAL HERITAGE
Quantitative plate counts provide results which can be reproduced, considering the low bar errors, and
give information relative to the percentage of growth inhibition according to exposure time. More
experiments would supplement first data and so the shorter time necessary to inhibit all fungal spores
would be determined.
Moreover, according to first results, the nature of gas mixture does not seem to be a preponderant
parameter in the decontamination process. No significant differences were observed by increasing the
percentage of oxygen to 0 to 5 and 20%. Some more runs with different treatment duration and gas
mixtures may reveal the most effective plasma parameters.
Otherwise, fluorescence microscopy observations only give few qualitative information as far as spore
viability is concerned, due to a problem of glass slides preparation. This characterisation mean is now
being improved in order to avoid this problem.
6. Conclusion and perspective
To conclude, this study emphases the efficiency of a new curative anti-fungal treatment realised at
atmospheric pressure.
Further experiments may improve these first promising results. Influence of several parameters has to
be studied such as the exposure time and the gas mixture. Moreover, new characterisation means could
give more information about spore viability, for example, scanning electron microscopy may show the
aspect of spores after plasma exposure.
Furthermore, to better understand mechanisms, reactive species composing the afterglow have to be
analysed more precisely.
Finally, best plasma parameters once defined, assessment of the efficiency of the afterglow will be
investigate on contaminated wood.
Acknowledgements
This work is financially supplied by the French national research program ANR-PLASMAPAL,
realised with the support of public institutions and companies partners: BEYNEL-MANUSTOCK (M.
Gerard VIERGE, coordinator), FP BOIS, ACXYS Technologies, ARNAUD SA, Projection Plasma
Système, FCBA, LRMH-CPP, LEGP, USBB, LAPLACE.
References
1. Moisan, Barbeau, Crevier, Pelletier, Philip and Saoudi (2002): Plasma sterilization. Methods and
mechanisms. Pure Appl. Chem. 74(3): 349-358.
2. Laroussi and Leipold (2004): Evaluation of the roles of reactive species, heat, and UV radiation in
the inactivation of bacterial cells by air plasmas at atmospheric pressure. Int. J. Mass. Spectrom.
233: 81-86.
3. Tanino, Xilu, Takashima, Katsura and Mizuno (2005): Sterilization using dielectric barrier
discharge at atmospheric pressure. Industry Applications Conference. Fourtieth IAS Annual
Meeting. Conference. 2: 784-788.
4. Moisan, Barbeau, Moreau, Pelletier, Tabrizian and Yahia (2001): Low-temperature sterilization
using gas plasmas: a review of the experiments and an analysis of the inactivation mechanisms.
Int. J. Pharm. 226: 1-21.
5. Hickey, P.C., Swift, S.M., Roca, M.G. and Read, N.D. (2005): Live-cell imaging of filamentous
fungi using vital fluorescent dyes. Methods in Microbiology. 34: 63-87.
6. Jones and Senft (1985): An improved method to determine cell viability by simultaneous staining
with fluorescein. J. Histochem. and Cytochem. 33: 77-79.
105