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End date: 2023 Ă— Start date: 2020 Ă— End date: 2020 Ă— Has files: Yes Ă— Subject: atmospheric pressure Ă— WGL Institute: INP Ă—

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    Plasma-based VAD process for multiply doped glass powders and high-performance fiber preforms with outstanding homogeneity
    (Hoboken, NJ : Wiley Interscience, 2020) Trautvetter, Tom; Schäfer, Jan; Benzine, Omar; Methling, Ralf; Baierl, Hardy; Reichel, Volker; Dellith, Jan; Köpp, Daniel; Hempel, Frank; Stankov, Marjan; Baeva, Margarita; Foest, RĂ¼diger; Wondraczek, Lothar; Wondraczek, Katrin; Bartelt, Hartmut
    An innovative approach using the vapor axial deposition (VAD), for the preparation of silica-based high-power fiber laser preforms, is described in this study. The VAD uses a plasma deposition system operating at atmospheric pressure, fed by a single, chemically adapted solution containing precursors of laser-active dopants (e.g., Yb2O3), glass-modifier species (e.g., Al2O3), and the silica matrix. The approach enables simultaneous doping with multiple optically active species and overcomes some of the current technological limitations encountered with well-established fiber preform technologies in terms of dopant distribution, doping levels, and achievable active core diameter. The deposition of co-doped silica with outstanding homogeneity is proven by Raman spectroscopy and electron probe microanalysis. Yb2O3 concentrations are realized up to 0.3 mol% in SiO2, with simultaneous doping of 3 mol% of Al2O3.
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    Persistent effectivity of gas plasma-treated, long time-stored liquid on epithelial cell adhesion capacity and membrane morphology
    (San Francisco, CA : Public Library of Science, 2014) Hoentsch, M.; Bussiahn, R.; Rebl, H.; Bergemann, C.; Eggert, M.; Frank, M.; Von Woedtke, T.; Nebe, B.
    Research in plasma medicine includes a major interest in understanding gas plasma-cell interactions. The immediate application of gas plasma in vitro inhibits cell attachment, vitality and cell-cell contacts via the liquid. Interestingly, in our novel experiments described here we found that the liquid-mediated plasma effect is long-lasting after storage up to seven days; i. e. the liquid preserves the characteristics once induced by the argon plasma. Therefore, the complete Dulbecco's Modified Eagle cell culture medium was argon plasma-treated (atmospheric pressure, kINPen09) for 60 s, stored for several days (1, 4 and 7 d) at 37°C and added to a confluent mouse hepatocyte epithelial cell (mHepR1) monolayer. Impaired tight junction architecture as well as shortened microvilli on the cell membrane could be observed, which was accompanied by the loss of cell adhesion capacity. Online-monitoring of vital cells revealed a reduced cell respiration. Our first timedependent analysis of plasma-treated medium revealed that temperature, hydrogen peroxide production, pH and oxygen content can be excluded as initiators of cell physiological and morphological changes. The here observed persisting biological effects in plasma-treated liquids could open new medical applications in dentistry and orthopaedics.
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    Numerical analysis of the effect of nitrogen and oxygen admixtures on the chemistry of an argon plasma jet operating at atmospheric pressure
    ([London] : IOP, 2015) Van Gaens, W.; Iseni, S.; Schmidt-Bleker, A.; Weltmann, K.-D.; Reuter, S.; Bogaerts, A.
    In this paper we study the cold atmospheric pressure plasma jet, called kinpen, operating in Ar with different admixture fractions up to 1% pure ${{{\rm N}}_{2}}$, ${{{\rm O}}_{2}}$ and ${{{\rm N}}_{2}}$ + ${{{\rm O}}_{2}}$. Moreover, the device is operating with a gas curtain of dry air. The absolute net production rates of the biologically active ozone (${{{\rm O}}_{3}}$) and nitrogen dioxide (${\rm N}{{{\rm O}}_{2}}$) species are measured in the far effluent by quantum cascade laser absorption spectroscopy in the mid-infrared. Additionally, a zero-dimensional semi-empirical reaction kinetics model is used to calculate the net production rates of these reactive molecules, which are compared to the experimental data. The latter model is applied throughout the entire plasma jet, starting already within the device itself. Very good qualitative and even quantitative agreement between the calculated and measured data is demonstrated. The numerical model thus yields very useful information about the chemical pathways of both the ${{{\rm O}}_{3}}$ and the ${\rm N}{{{\rm O}}_{2}}$ generation. It is shown that the production of these species can be manipulated by up to one order of magnitude by varying the amount of admixture or the admixture type, since this affects the electron kinetics significantly at these low concentration levels.