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Plasma Science, IEEE Transactions on

Issue 11  Part 2 • Date Nov. 2012

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Displaying Results 1 - 14 of 14
  • Table of Contents

    Page(s): C1
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  • IEEE Transactions on Plasma Science publication information

    Page(s): C2
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  • Special Issue on Nonthermal Medical/Biological Applications Using Ionized Gases and Electromagnetic Fields

    Page(s): 2961 - 2962
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  • New Nonthermal Atmospheric-Pressure Plasma Sources for Decontamination of Human Extremities

    Page(s): 2963 - 2969
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    The research and development of plasma sources, which can be used for therapeutic applications in the new and emerging field of plasma medicine, has gained more and more interest during recent years. These applications require cold nonthermal plasmas operating at atmospheric pressure. Due to the fact that, in general, plasma on or in the human body is a challenge both for medicine and plasma physics, basic research combining experimental physical and biological investigation and modeling is necessary to provide the required knowledge for therapeutic applications. It turned out that each application needs a special tailor-made plasma source, passing a minimum set of physical and biological tests before it can be considered for medical use. In addition to atmospheric-pressure plasma jets, dielectric barrier discharges offer great potential for a variety of medical indications. A new 2-D and even 3-D acting plasma source is introduced, exemplified for a possible decontamination of human extremities or similar tasks. In contradiction to most of today's existing plasma sources with fixed electrodes and nozzles, the prototype uses flexible electrodes to automatically adapt the plasma under equal and stable conditions to nearly all surface structures. First, physical and biological investigations demonstrate the general potential for therapeutic applications on preferably intact skin surfaces. View full abstract»

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  • Comparison of Nonthermal Plasma Processes on the Surface Properties of Polystyrene and Their Impact on Cell Growth

    Page(s): 2970 - 2979
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    The initial adhesion and spreading of cells are crucial factors for the successful performance of a synthetic biomaterial used for cell culture disposables or human medical devices (e.g., implants). Surface properties which allow the control of the attachment of cells are decisive for the acceptance of the provided material. Hence, different surface preparation techniques are used to equip surfaces with functional groups to improve initial surface interactions. In this paper, polystyrene (PS) surfaces were modified by using different nonthermal plasma processes. In particular, low-pressure plasma and atmospheric-pressure plasma were applied to modify surfaces or to deposit thin films on surfaces. Furthermore, the behaviors of human osteoblastic cells with respect to cell viability and cell growth on differently plasma treated PS surfaces are investigated. A comparison is made between plasma-grafted PS and commercially available PS-such as tissue-culture PS and Primaria. The cell studies were accompanied by surface analysis comprising atomic force microscopy, determination of surface energies, and X-ray photoelectron spectroscopy measurements. This work demonstrates that the functionalization of PS substrates by applying low-pressure and atmospheric-pressure plasma processes are equally effective in the improvement of cell attachment and proliferation. Furthermore, it is shown that the enhanced metabolic activity and spreading behavior of osteoblastic cells correlate well with an increase in surface wettability and the introduction of polar oxygen- and/or nitrogen-containing functional groups after plasma treatment. View full abstract»

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  • Effects of Atmospheric-Pressure Plasma Jet on Pepsin Structure and Function

    Page(s): 2980 - 2985
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    The atmospheric-pressure plasma jets (APPJs) are nonthermal plasma sources studied for their high potential in many medical applications where conventional solutions failed. In this paper, we show the influence of helium APPJ on pepsin structure and function. The APPJ source is characterized using voltage-current measurements, optical emission spectroscopy, and high-speed imaging. Pepsin powder was exposed to the action of the plasma jet, and then, spectroscopic investigations were carried out to obtain information on the structural modifications. Protein function was tested using an enzymatic assay. View full abstract»

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  • From RONS to ROS: Tailoring Plasma Jet Treatment of Skin Cells

    Page(s): 2986 - 2993
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    Finding a solution for air species contamination of atmospheric pressure plasmas in plasma medical treatment is a major task for the new field of plasma medicine. Several approaches use complex climate chambers to control the surrounding atmosphere. In this paper, ambient species are excluded in plasma-human-skin-cell treatment by ensheathing the plasma jet effluent with a shielding gas. Not only does this gas curtain protect the plasma jet effluent from inflow of air species but it also, more importantly, allows controlling the effluent reactive species composition by adjusting the mixture of the shielding gas. In the present investigations, the mixture of nitrogen to oxygen within the gas curtain around an argon atmospheric pressure plasma jet (kinpen) is varied. The resulting reactive plasma components produced in the jet effluent are thus either oxygen or nitrogen dominated. With this gas curtain, the effect of reactive oxygen species (ROS) and reactive nitrogen species (RNS) on the cell viability of indirectly plasma-treated HaCaT skin cells is studied. This human keratinocyte cell line is an established standard for a skin model system. The cell viability is determined by a fluorometric assay, where metabolically active cells transform nonfluorescent resazurin to the highly fluorescent resorufin. Plasma jet and gas curtain are characterized by numerical flow simulation as well as by optical emission spectroscopy. The generation of nitrite within the used standard cell culture medium serves as a measure for generated RNS. Measurements with the leukodye dichlorodihydrofluorescein diacetate show that, despite a variation of the shielding gas mixture, the total amount of generated reactive oxygen plus nitrogen species is constant. It is shown that a plasma dominated by RNS disrupts cellular growth less than a ROS-dominated plasma. View full abstract»

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  • Generation of Active Species in a Large Atmospheric-Pressure Plasma Jet

    Page(s): 2994 - 3002
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    Low-temperature atmospheric-pressure plasma jets (APPJs) are being increasingly used in surface activation, cleaning, wound care, and sterilization applications. The development of successful applications using these systems depends on the ability to tailor the active species generated in the plasma jets to match the treatment requirements. This paper presents an investigation of the effect of sinusoidal drive frequency (20-140 kHz), on a helium discharge formed using an APPJ. The discharge was formed in a large-orifice 16-mm-diameter quartz tube with a treatment area of ≈ 2cm2 at the nozzle exit. Optical, polychromic emission, and thermographic imaging data were correlated with electrical measurements. These measurements indicated that the coupling efficiency was frequency dependent. As a result of differences in coupling efficiency, variations in active species (N2, N2+, O, and NO) present in the discharge were observed. The concentration of active species was also dependent on the distance from the powered electrodes. As well as altering the concentration of active species in the discharge, changes in frequency resulted in higher discharge temperatures (25 °C at 20 kHz to 40 °C at 80 kHz). The temperature was measured on the quartz tube, and steady state was reached after 120 s. This paper presents a detailed analysis of the frequency/distance dependence on the active species in the discharge. This dependence makes it possible to control the active species present at the plasma jet orifice by tailoring the frequency and tube length. View full abstract»

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  • Highly Effective Large-Area Inactivation of B. subtilis Spore Using a Planar Dielectric Barrier Discharge Jet With  \hbox {CF}_{4} /Air Mixture

    Page(s): 3003 - 3006
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    In this paper, we demonstrate that, by adding a small amount of CF4 (2%) into a compressed-air planar dielectric barrier discharge (DBD), one can effectively inactivate a B. subtilis spore up to 50 mm in width in the postdischarge jet region after ten passes of exposure of plasma plume (equivalent plasma exposure time of 1 s) for treatment distance of up to 14 mm for the spore concentration in the range of 105-107 CFU/mL. A possible mechanism is proposed, i.e., the chemically active F atoms and CF (n = 1 - 3) are generated through the help of abundant excited nitrogen molecules in the postdischarge region. View full abstract»

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  • Cold DC-Operated Air Plasma Jet for the Inactivation of Infectious Microorganisms

    Page(s): 3007 - 3026
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    We evaluated a nonthermal plasma jet for a respective use to prevent infections from bacteria and yeasts. The plasma jet is generated from the flow of ambient air with 8 slm through a microhollow cathode discharge assembly that is operated with a direct current of 30 mA. With these parameters, the temperature in the jet reaches 43 °C at 10 mm from the discharge. Agar plates that were inoculated with Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Candida kefyr were treated at this distance, moving the plates through the jet in a meander that covered a 2 cm by 2 cm area. Different exposure times were realized by changing the speed of the movement and adjusting the distance between consecutive passes. S. aureus was most responsive to the exposure with a reduction in the number of colony forming units of 5.5 log steps in 40 s. All other microorganisms show a more gradual inactivation with exposure times. For all bacteria, a clearing of the treated area is achieved in about 2.5-3.5 min, corresponding to log-reduction factors of 5.5-6.5. Complete inactivation of the yeast requires about 7 min. Both S. aureus and C. kefyr show considerable inactivation also outside the immediate treatment area, while P. aeruginosa and A. baumannii do not. We conclude that differences in the morphologies of the membrane structures are responsible for the diverging results, together with a targeted response to different agents provided with the plasma jet. For the gram negative bacteria, we hold short-lived agents, acting across a short range, responsible, while for the other microorganisms, longer lived species seem more important. Our measurements show that neither heat, ultraviolet radiation, nor the generation of ozone can be responsible for the observed results. The most prominent long lived reaction product found is nitric oxide, which, by itself or through induced chemical reactions, might affect cell viability. View full abstract»

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  • Announcement: Special Issue for Selected Papers from EAPPC/BEAMS 2012 IEEE Transactions on Plasma Science (October 2013)

    Page(s): 3027
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  • Open access

    Page(s): 3028
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  • IEEE Transactions on Plasma Science information for authors

    Page(s): C3
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  • Affiliate Plan of the IEEE Nuclear and Plasma Sciences Society

    Page(s): C4
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IEEE Transactions on Plasma Sciences focuses on plasma science and engineering, including: magnetofluid dynamics and thermionics; plasma dynamics; gaseous electronics and arc technology.

 

 

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Editor-in-Chief
Steven J. Gitomer, Ph.D.
Senior Scientist, US Civilian Research & Development Foundation
Guest Scientist, Los Alamos National Laboratory
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