Bulletin of the American Physical Society
2006 59th Annual Gaseous Electronics Conference
Tuesday–Friday, October 10–13, 2006; Columbus, Ohio
Session CT2: Collision Processes with Biological and Environmental Applications |
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Chair: Birgit Lohmann, Griffith University, Australia Room: Holiday Inn Salon B |
Tuesday, October 10, 2006 10:00AM - 10:30AM |
CT2.00001: Nanoscale Interactions Driving Macroscopic Phenomena: New Insights into the role of Electron-Driven Processes in Atmospheric Behaviour Invited Speaker: Electrons with energies over a wide range (eV to keV) drive a variety of atomic processes, such as ionisation and excitation of atoms and molecules. The products then play a role in the chemical reactions that occur in the atmosphere, and so influence macroscopic parameters, such as the density of minor constituents and the electron density. This talk describes new insights into the role of these electron-driven processes in atmospheric behaviour. [Preview Abstract] |
Tuesday, October 10, 2006 10:30AM - 11:00AM |
CT2.00002: Electron processing at low energies: from basics to environmental and biological applications. Invited Speaker: Electron initiated reactions play a key role in nearly any field of pure and applied sciences, in the gas phase as well as in condensed phases or at interfaces. This include substrate induced photochemistry, radiation damage of biological material (and, accordingly, the molecular mechanisms, how radio sensitizers used in tumour therapy operate), reactions induced by electrons in surface tunnelling microscopy (STM), or any kind of plasma used in industrial plasma processing. In each of these fields the electron-molecule interaction represents a key step within an eventually complex reaction sequence. A particularly interesting field is the interaction of electrons with molecules at energies below the level of electronic excitation. In this range many molecules exhibit large cross sections for resonant electron capture, often followed by the decomposition of the transient negative compound (M$^{-\# })$ according to e$^{-}$ + M --$>$ M$^{-\# }$ --$>$ R + X$^{-}$.$^{ }$ We report on such dissociative electron attachment (DEA) processes studied at different stages of aggregation, namely in single molecules under collision free conditions, in clusters formed by supersonic gas expansion, and on the surface of solids or in molecular nanofilms. In the meantime it has also been recognised that in the damage of living cells by high energy radiation the attachment of low energy secondary electrons to DNA is a key initial process leading to strand breaks. These secondary electrons are created along the ionisation track of the primary high-energy quantum. Apart from that, bio-molecular systems exhibit unique features in DEA, like bond and site selective decompositions. [Preview Abstract] |
Tuesday, October 10, 2006 11:00AM - 11:30AM |
CT2.00003: Interaction of cold plasmas with biological cells: What we have learned so far Invited Speaker: In the last two decades, non-equilibrium, low temperature, atmospheric pressure plasmas have gained acceptance as an attractive technological solution in industrial applications such as the surface modification of polymers and the cleaning of flue gases. As more reliable ``cold'' plasma sources are developed, new and interesting applications continue to emerge. Amongst the more recent applications, the use of atmospheric pressure cold plasmas in the biomedical field is presently experiencing a heightened interest from the plasma science research community. This is due to promising possibilities to use these plasmas in medical research such as wound healing, tissue engineering, surface modification of biocompatible materials, and the sterilization of reusable heat-sensitive medical instruments. However, before any of these exciting possibilities become reality, an in-depth understanding of the effects of plasma on the cellular and sub-cellular levels has to be achieved. In this paper, a review of the knowledge that has been gained during the last few years will be presented. First an overview of research efforts on the inactivation of bacterial cells will be presented. This includes the evaluation of the inactivation kinetics and the roles played by the various plasma agents (such as UV photons and free radicals) in the inactivation process. In the second part of this talk, plasma sub-lethal effects on both prokaryotic and eukaryotic cells will be discussed. Finally, the prospects of the use of ``cold'' plasmas in the biomedical field are outlined. [Preview Abstract] |
Tuesday, October 10, 2006 11:30AM - 11:45AM |
CT2.00004: Electron Collisions with Formic Acid and Tetrahydrofuran V. Vizcaino, J.P. Sullivan, S.J. Buckman, C. Colyer We have measured absolute elastic electron scattering cross sections for the biologically relevant molecules CHOOH (formic acid) and C$_4$H$_8$O (tetrahydrofuran - THF). The formate group is an important constituent of a number of amino acids and THF forms part of the DNA backbone. The experiments cover the energy range from 1 to 50 eV and include both angular and energy dependent measurements. We make comparisons with a number of theoretical approaches, including the Kohn variational, and R- matrix techniques and a calculation based on a density functional technique. [Preview Abstract] |
Tuesday, October 10, 2006 11:45AM - 12:00PM |
CT2.00005: Non-thermal atmospheric plasmas in dentistry Raymond Sladek, Eva Stoffels Non-thermal atmospheric plasmas are very efficient in the deactivation of bacteria. A relatively new area is the use of these plasmas in biomedical and dental applications. In this work, application of a novel device in dentistry is investigated, the plasma needle. The plasma needle is used to generate a non-thermal atmospheric micro-plasma. A promising application of this micro-plasma is the treatment of dental cavities, to stop caries without causing pain and removing too much healthy tissue. Various bacterial model systems are used to test the bactericidal efficiency of the plasma needle: bacteria in droplets, thin films and (multi-species) biofilms. The effects of plasma needle treatment on bacterial viability, growth and composition are discussed. The results indicate that plasma can become a useful tool for dental treatment. [Preview Abstract] |
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