WorldWideScience

Sample records for atmospheric pressure microplasma

  1. Special issue: diagnostics of atmospheric pressure microplasmas

    Science.gov (United States)

    Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

    2013-11-01

    In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of

  2. Microplasma deposition of challenging thin films at atmospheric pressure

    Science.gov (United States)

    Hopwood, Jeffrey; Thejaswini, H. C.; Plasma Engineering Laboratory Team

    2015-09-01

    Non-equilibrium microplasmas produce fluxes of ions and excited species to a surface while maintaining the surface near room temperature. At atmospheric pressure, however, it is very difficult to accelerate the highly collisional ions. While many applications do not benefit from energetic interactions between plasma and surface, conventional plasma deposition of thin films often requires either ion bombardment or substrate heating. For example, diamondlike carbon (DLC) is known to require ~ 100 eV ion bombardment and transparent conducting oxides (TCO) typically require substrate temperatures on the order of 400-500 K. A microwave-induced microplasma is used to dissociate dilute precursor molecules within flowing helium. The precursor and plasma species result in rapid deposition of thin films (>1 μm/min). This plasma produces a steady-state ion flux of 6×1017 cm-2s-1, which is more than two orders of magnitude greater than a low pressure capacitively coupled plasma. Likewise, the metastable density is roughly two orders greater. These and other microplasma diagnostics are correlated with the measured film properties of microplasma-deposited DLC and TCO. This study shows that high ion flux, even at low energy (~ 1 eV), can provide the needed surface interactions to produce these materials at room temperature.

  3. Heat transport of nitrogen in helium atmospheric pressure microplasma

    CERN Document Server

    Xu, Shaofeng

    2013-01-01

    Stable DC atmospheric pressure normal glow discharges in ambient air were produced between the water surface and the metallic capillary coupled with influx of helium gas. Multiple independent repeated trials indicated that vibrational temperature of nitrogen rises from 3200 to 4622 K, and rotational temperature of nitrogen decreases from 1270 to 570 K as gas flux increasing from 20 to 80 sccm and discharge current decreasing from 11 to 3 mA. Furthermore, it was found that the vibrational degree of the nitrogen molecule has priority to gain energy than the rotational degree of nitrogen molecule in nonequilibrium helium microplasma.

  4. Collaborative Research. Atmospheric Pressure Microplasma Chemistry-Photon Synergies

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung-Jin [Univ. of Illinois, Urbana, IL (United States); Eden, James Gary [Univ. of Illinois, Urbana, IL (United States)

    2015-12-01

    Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources offers the promise of greatly expanding the range of applications for each of them. The plasma sources create active chemical species and these can be activated further by the addition of photons and the associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. This project combined the construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling. Through a continuous discussion and co-design process with the UC-Berkeley Team, we have successfully completed the fabrication and testing of all components for a microplasma array-assisted system designed for photon-activated plasma chemistry research. Microcavity plasma lamps capable of generating more than 20 mW/cm2 at 172 nm (Xe dimer) were fabricated with a custom form factor to mate to the plasma chemistry setup, and a lamp was current being installed by the Berkeley team so as to investigate plasma chemistry-photon synergies at a higher photon energy (~7.2 eV) as compared to the UVA treatment that is afforded by UV LEDs operating at 365 nm. In particular, motivated by the promising results from the Berkeley team with UVA treatment, we also produced the first generation of lamps that can generate photons in the 300-370 nm wavelength range. Another set of experiments, conducted under the auspices of this grant, involved the use of plasma microjet arrays. The combination of the photons and excited radicals produced by the plasma column resulted in broad area deactivation of bacteria.

  5. Collaborative Research: Atmospheric Pressure Microplasma Chemistry-Photon Synergies Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Graves, David [Univ. of California, Berkeley, CA (United States)

    2017-02-07

    Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources shows greatly expanded range of applications of each of them. The plasma sources create active chemical species and these can be activated further by addition of photons and associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. The project combines construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling.

  6. Electric and spectroscopic properties of argon-hydrogen RF microplasma jets at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Souza-Correa, J A; Oliveira, C; Amorim, J [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol-CTBE, Caixa Postal 6170, 13083-970, Campinas, Sao Paulo (Brazil); Gomes, M P, E-mail: jorge.correa@bioetanol.org.b, E-mail: carlos.filho@bioetanol.org.b, E-mail: gomesmp@ita.b, E-mail: jayr.amorim@bioetanol.org.b [Departamento de Fisica, Instituto Tecnologico de Aeronautica-ITA, Praca Marechal Eduardo Gomes 50, 12.228-900, Sao Jose dos Campos, Sao Paulo (Brazil)

    2010-10-06

    Microplasma jets of argon-hydrogen (Ar-H{sub 2}) gas mixture were generated by 144.0 MHz radio-frequency (RF) waves at powers of 5 W, 10 W, 20 W and 50 W. The experimental setup employed creates stable microplasmas at atmospheric pressure from 5.0 mm up to 20.0 mm visual glow lengths. We have determined the rms voltages, the rms electric currents and the power absorptions of these microplasma jets. By making use of optical spectroscopy, the emission spectra of Ar-H{sub 2} microplasma jets were recorded in the range 3060-8200 A, in order to estimate the axial distribution profiles of electron density, rotational temperature, excitation temperature and hydrogen atomic temperature.

  7. Non-equilibrium atmospheric pressure microplasma jet: An approach to endoscopic therapies

    Science.gov (United States)

    Zuo, Xiao; Wei, Yu; Wei Chen, Long; Dong Meng, Yue; Plasma Medicine Team

    2013-08-01

    Atmospheric pressure microplasma jet generated in a long hollow core optical fiber is studied to verify the potential feasibility of endoscopic therapies. Thermal damage and electric shock to the human body were suppressed by two technical methods, i.e., the high-voltage resistant flexible tube wrapped on the optical fiber and a power resistor of 100 kΩ connected between the power supply and the copper foil electrode. Optical emission spectra analysis indicated that many kinds of active radicals like excited atomic O and OH, were generated in the microplasma jet. In addition, the applications of the microplasma jet on sterilization and lung cancer cell apoptosis were presented. After 5 min of exposures to the microplasma jet, the cell viability and the bacillus subtilis replication decreased to about 3% and zero, respectively. More investigations are needed to improve the plasma-aided endoscopic therapies.

  8. Production of Energetic Active-Oxygen Species at Atmospheric Pressure by Linear Microplasma Arrays

    Science.gov (United States)

    Rawlins, Wilson; Galbally-Kinney, Kristin; Davis, Steven; Hoskinson, Alan; Hopwood, Jeffrey

    2014-10-01

    Linear arrays of stripline resonators operated at microwave frequencies and low powers provide spatially and temporally continuous micro-discharges with high E/N at atmospheric pressure. When implemented in a discharge-flow reactor, these microplasmas excite metastable singlet molecular oxygen and dissociate oxygen molecules to produce atomic oxygen, with efficiencies comparable to conventional microwave resonant cavities at low pressures. At elevated pressure, production of atomic oxygen leads to prompt formation of ozone immediately downstream of the discharge exit. We have observed and quantified the production of O2(a 1 Δ) metastables and O3 in the effluent of linear microplasma arrays for O2/He, O2/Ar, O2/N2/He,andO2/N2/Ar mixtures as functions of pressure, gas flow rate, and species mixing ratio. We compare results for single-array microplasmas, where the discharge products are formed in a small volume and entrained into the bulk flow, and overlapping dual-array microplasmas which process larger gas flow volumes. Supported by the Air Force Research Laboratory and Department of Energy.

  9. Characterization of atmospheric pressure microplasma produced from argon and a mixture of argon–ethylenediamine

    Energy Technology Data Exchange (ETDEWEB)

    Bashir, M., E-mail: ranabashir77@gmail.com [Department of Chemical and Biological Engineering and Kroto Research Institute, University of Sheffield, Sheffield S1 3JD (United Kingdom); Rees, Julia M.; Bashir, S. [School of Mathematics and Statistics, Hicks Building, Hounsfield Road, University of Sheffield, Sheffield S3 7RH (United Kingdom); Zimmerman, William B. [Department of Chemical and Biological Engineering and Kroto Research Institute, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2014-06-27

    A non-thermal atmospheric pressure microplasma generated from pure argon (Ar) and a mixture of argon–ethylenediamine vapors (Ar/EDA) has been characterized in this study. A sinusoidal power supply operating at 30 kHz was used to excite microplasma in a rectangular borosilicate glass capillary (4×0.4 mm{sup 2}). The monomer EDA was mixed with Ar in order to perform plasma polymerization inside the microchannel. The analyses were made by measuring spectroscopic and electrical parameters of the discharge. The effects of EDA mixing on plasma parameters such as electron, excitation and rotational temperatures during the process of surface coating of the microchannel were investigated. These parameters play an important role in the deposition process. The plasma temperatures estimated through spectroscopic measurement were found in the sequence T{sub e}>T{sub exc}>T{sub vib}>T{sub rot}, which indicated the non-thermal characteristics of the proposed DBD microplasma. The parameters of the Ar discharge were also numerically computed using plasma simulations. The numerical predictions of electron temperature (2D simulations) and electron density (3D simulations) were found to be in close agreement to those estimated through experiments. - Highlights: • An atmospheric pressure microplasma was generated in a borosilicate glass capillary. • A pure argon and a mixture of argon–ethylenediamine plasmas were characterized. • Characterization was performed by emission spectrometry and electrical measurements. • Plasma parameters were also predicted by numerical simulations. • The sequence of estimated plasma temperatures indicated its non-thermal behaviour.

  10. Optical emission spectroscopy diagnostics of an atmospheric pressure direct current microplasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Sismanoglu, B.N., E-mail: bogos@ita.b [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Comando-Geral de Tecnologia Aeroespacial, Pca Marechal Eduardo Gomes 50, 12 228-900, Sao Jose dos Campos, SP (Brazil); Amorim, J., E-mail: jayr.amorim@bioetanol.org.b [Centro de Ciencia e Tecnologia do Bioetanol - CTBE, Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil); Souza-Correa, J.A., E-mail: jorge.correa@bioetanol.org.b [Centro de Ciencia e Tecnologia do Bioetanol - CTBE, Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil); Oliveira, C., E-mail: carlosf@ita.b [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Comando-Geral de Tecnologia Aeroespacial, Pca Marechal Eduardo Gomes 50, 12 228-900, Sao Jose dos Campos, SP (Brazil); Gomes, M.P., E-mail: gomesmp@ita.b [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Comando-Geral de Tecnologia Aeroespacial, Pca Marechal Eduardo Gomes 50, 12 228-900, Sao Jose dos Campos, SP (Brazil)

    2009-11-15

    This paper is about the use of optical emission spectroscopy as a diagnostic tool to determine the gas discharge parameters of a direct current (98% Ar-2% H{sub 2}) non-thermal microplasma jet, operated at atmospheric pressure. The electrical and optical behaviors were studied to characterize this glow discharge. The microplasma jet was investigated in the normal and abnormal glow regimes, for current ranging from 10 to 130 mA, at approx 220 V of applied voltage for copper cathode. OH (A {sup 2}SIGMA{sup +}, nu = 0 -> X {sup 2}PI, nu' = 0) rotational bands at 306.357 nm and also the 603.213 nm Ar I line, which is sensitive to van der Waals broadening, were used to determine the gas temperature, which ranges from 550 to 800 K. The electron number densities, ranging from 6.0 x 10{sup 14} to 1.4 x 10{sup 15} cm{sup -3}, were determined through a careful analysis of the main broadening mechanisms of the H{sub beta} line. From both 603.213 nm and 565.070 nm Ar I line broadenings, it was possible to obtain simultaneously electron number density and temperature (approx 8000 K). Excitation temperatures were also measured from two methods: from two Cu I lines and from Boltzmann-plot of 4p-4s and 5p-4s Ar I transitions. By employing H{sub alpha} line, the hydrogen atoms' H temperature was estimated (approx 18,000 K) and found to be surprisingly hotter than the excitation temperature.

  11. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

    Directory of Open Access Journals (Sweden)

    Renwu Zhou

    Full Text Available Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS. Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma.

  12. Self-assembled Ag nano-patterns forming in downflow of ammonia-Ar atmospheric pressure microplasmas

    Science.gov (United States)

    Kihara, Naoya; Blanquet, Ella; Sakai, Osamu

    2014-10-01

    Fractal-like Ag nano-patterns were observed after drying silver nitrate solution in downflow of ammonia-Ar atmospheric pressure microplasmas. These atmospheric-pressure microplasmas generated hydrazine, and this hydrazine density in their downflow region was in the order of 1015 cm-3. As hydrazine is a very strong reducing agent, Ag nano-particles were extracted from the silver nitrate solution. The Ag nano-structures were fractal-like patterns, with fractal dimension range of 1.6--1.9. The network structures in these patterns with several mm diameter showed good electric conductivity and extraordinary optical responses, which will be favorable for future low-cost optical metamaterials.

  13. Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma

    Science.gov (United States)

    Lee, H. J.; Shon, C. H.; Kim, Y. S.; Kim, S.; Kim, G. C.; Kong, M. G.

    2009-11-01

    Increased expression of integrins and focal adhesion kinase (FAK) is important for the survival, growth and metastasis of melanoma cells. Based on this well-established observation in oncology, we propose to use degradation of integrin and FAK proteins as a potential strategy for melanoma cancer therapy. A low-temperature radio-frequency atmospheric microplasma jet is used to study their effects on the adhesion molecules of G361 melanoma cells. Microplasma treatment is shown to (1) cause significant cell detachment from the bottom of microtiter plates coated with collagen, (2) induce the death of human melanoma cells, (3) inhibit the expression of integrin α2, integrin α4 and FAK on the cell surface and finally (4) change well-stretched actin filaments to a diffuse pattern. These results suggest that cold atmospheric pressure plasmas can strongly inhibit the adhesion of melanoma cells by reducing the activities of adhesion proteins such as integrins and FAK, key biomolecules that are known to be important in malignant transformation and acquisition of metastatic phenotypes.

  14. Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H J [Department of Electrical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Shon, C H [Korea Electrotechnology Research Institute, Changwon 641-120 (Korea, Republic of); Kim, Y S; Kim, S [Department of Pediatric Dentistry, Pusan National University, Busan 602-739 (Korea, Republic of); Kim, G C [Department of Oral Anatomy, Pusan National University, Busan 602-739 (Korea, Republic of); Kong, M G [Department of Electronics and Electrical Engineering, Loughborough University, Leics LE11 3TU (United Kingdom)], E-mail: ki9100m@pusan.ac.kr, E-mail: m.g.kong@lboro.ac.uk

    2009-11-15

    Increased expression of integrins and focal adhesion kinase (FAK) is important for the survival, growth and metastasis of melanoma cells. Based on this well-established observation in oncology, we propose to use degradation of integrin and FAK proteins as a potential strategy for melanoma cancer therapy. A low-temperature radio-frequency atmospheric microplasma jet is used to study their effects on the adhesion molecules of G361 melanoma cells. Microplasma treatment is shown to (1) cause significant cell detachment from the bottom of microtiter plates coated with collagen, (2) induce the death of human melanoma cells, (3) inhibit the expression of integrin {alpha}{sub 2}, integrin {alpha}{sub 4} and FAK on the cell surface and finally (4) change well-stretched actin filaments to a diffuse pattern. These results suggest that cold atmospheric pressure plasmas can strongly inhibit the adhesion of melanoma cells by reducing the activities of adhesion proteins such as integrins and FAK, key biomolecules that are known to be important in malignant transformation and acquisition of metastatic phenotypes.

  15. Atmospheric pressure microplasma assisted growth of silver nanosheets and their inhibitory action against bacteria of clinical interest

    Science.gov (United States)

    Iqbal, Tariq; Mukhtar, Masood; Khan, M. A.; Khan, Rashid; Zaman, Rehmat; Mahmood, Hasan; Zaka-ul-Islam, M.

    2016-12-01

    Two-dimensional staggered silver nanosheets were synthesized using a facile atmospheric microplasma electrochemical process at room temperature. It is an environmental friendly technique that does not include toxic reducing agents. In this technique, microplasma directly reduces Ag+ ions into an electrolyte solution. The synthesized silver nanosheets were investigated by scanning electron microscope, x-ray diffraction, ultraviolet-visible spectroscopy and fourier transform infrared spectroscopy. This type of morphology has not yet been reported using a microplasma technique. The antibacterial activity of the as-synthesized nanosheets against Klebsiella pneumoniae, the Staphylococcus strain, Escherichia coli and Acinetobacter was carried out using a disc diffusion method. The results indicated that these sheets show significant antibacterial activity against Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli and Acinetobacter compared with that of the standard antibiotic.

  16. Optically Pumped Lasing of Ar(4p -->4s) Excited in Linear Microplasma Arrays at Atmospheric Pressure

    Science.gov (United States)

    Rawlins, Wilson; Galbally-Kinney, Kristin; Davis, Steven; Hoskinson, Alan; Hopwood, Jeffrey

    2014-10-01

    The optically pumped rare-gas metastable laser is a chemically inert analogue to alkali laser systems. These devices require efficient generation of electronically excited metastable atoms in a continuous-wave electric discharge in flowing gas mixtures at elevated pressure. Linear arrays of microstrip resonators are well suited for this task. We have observed CW optical gain and lasing at 912 nm using linear micro-discharge arrays to generate metastable rare-gas atoms at atmospheric pressure. Ar(4s) metastables are generated in flowing Ar/He mixtures by low-power, CW linear array microplasmas operating near 900 MHz and 1 atm. The metastables are optically excited to selected states in the Ar(4p) manifold by a tunable, CW Ti:S laser. Collisional energy transfer within the manifold produces a population inversion. The Ar(4s) concentration and the optical gain are probed by tunable diode laser spectroscopy. Supported by the Air Force Research Laboratory and High Energy Laser Joint Technology Office.

  17. Characterization of Atmospheric Pressure Carbon Dioxide Dissociation in Arrays of Microplasma Channels by Emission Spectroscopy and Effluent Analysis

    Science.gov (United States)

    Dai, Zhen; Shin, Chul; Park, Sung-Jin; Eden, James Gary

    2014-10-01

    Levied by rigorous regulations, the enormous cost of atmospheric carbon dioxide emission urged voracious demands on remediation technologies globally. Microplasma technology is being investigated as a new candidate to efficiently dissociate or remediate carbon dioxide contained in atmosphere. At a flow rate of 60 sccm of pure CO2 feedstock gas, dissociation degree of up to 14% has been achieved with stable glow discharges in an array of Al/Al2O3 microplasma channels. In-situ characterizations of the effluent gases were conducted with residual gas analysis, gas chromatography, and infrared spectroscopy. Furthermore, time and spatially resolved emission spectroscopy recorded with an intensified charge-coupled device in the 300-800 nm region revealed the excitation of CO and C2 species. The implications on the possible plasma chemistry and its reaction mechanisms in the microdischarge will be discussed. Work supported by AFOSR.

  18. An experimental burn wound-healing study of non-thermal atmospheric pressure microplasma jet arrays.

    Science.gov (United States)

    Lee, Ok Joo; Ju, Hyung Woo; Khang, Gilson; Sun, Peter P; Rivera, Jose; Cho, Jin Hoon; Park, Sung-Jin; Eden, J Gary; Park, Chan Hum

    2016-04-01

    In contrast with a thermal plasma surgical instrument based on coagulative and ablative properties, low-temperature (non-thermal) non-equilibrium plasmas are known for novel medicinal effects on exposed tissue while minimizing undesirable tissue damage. In this study we demonstrated that arrays of non-thermal microplasma jet devices fabricated from a transparent polymer can efficiently inactivate fungi (Candida albicans) as well as bacteria (Escherichia coli), both in vitro and in vivo, and that this leads to a significant wound-healing effect. Microplasma jet arrays offer several advantages over conventional single-jet devices, including superior packing density, inherent scalability for larger treatment areas, unprecedented material flexibility in a plasma jet device, and the selective generation of medically relevant reactive species at higher plasma densities. The therapeutic effects of our multi-jet device were verified on second-degree burns in animal rat models. Reduction of the wound area and the histology of the wound after treatment have been investigated, and expression of interleukin (IL)-1α, -6 and -10 was verified to evaluate the healing effects. The consistent effectiveness of non-thermal plasma treatment has been observed especially in decreasing wound size and promoting re-epithelialization through collagen arrangement and the regulation of expression of inflammatory genes. Copyright © 2015 John Wiley & Sons, Ltd.

  19. Laser excitation dynamics of argon metastables generated in atmospheric pressure flows by microwave frequency microplasma arrays

    Science.gov (United States)

    Rawlins, W. T.; Galbally-Kinney, K. L.; Davis, S. J.; Hoskinson, A. R.; Hopwood, J. A.

    2014-03-01

    The optically pumped rare-gas metastable laser is a chemically inert analogue to diode-pumped alkali (DPAL) and alkali-exciplex (XPAL) laser systems. Scaling of these devices requires efficient generation of electronically excited metastable atoms in a continuous-wave electric discharge in flowing gas mixtures at atmospheric pressure. This paper describes initial investigations of the use of linear microwave micro-discharge arrays to generate metastable rare-gas atoms at atmospheric pressure in optical pump-and-probe experiments for laser development. Power requirements to ignite and sustain the plasma at 1 atm are low, 2p9 transition at 811.5 nm and the corresponding laser-induced fluorescence on the 2p10-->1s5 transition at 912.3 nm; the 2p10 state is efficiently populated by collisional energy transfer from 2p9. Using tunable diode laser absorption/gain spectroscopy, we observe small-signal gains of ~1 cm-1 over a 1.9 cm path. We also observe stable, continuous-wave laser oscillation at 912.3 nm, with preliminary optical efficiency ~55%. These results are consistent with efficient collisional coupling within the Ar(4s) manifold.

  20. Plasma-water interactions at atmospheric pressure in a dc microplasma

    Science.gov (United States)

    Patel, Jenish; Němcová, Lucie; Mitra, Somak; Graham, William; Maguire, Paul; Švrček, Vladimir; Mariotti, Davide

    2013-09-01

    Plasma-liquid interactions generate a variety of chemical species that are very useful for the treatment of many materials and that makes plasma-induced liquid chemistry (PiLC) very attractive for industrial applications. The understanding of plasma-induced chemistry with water can open up a vast range of plasma-activated chemistry in liquid with enormous potential for the synthesis of chemical compounds, nanomaterials synthesis and functionalization. However, this basic understanding of the chemistry occurring at the plasma-liquid interface is still poor. In the present study, different properties of water are analysed when processed by plasma at atmospheric-pressure with different conditions. In particular, pH, temperature and conductivity of water are measured against current and time of plasma processing. We also observed the formation of molecular oxygen (O2) and hydrogen peroxide (H2O2) for the same plasma conditions. The current of plasma processing was found to affect the water properties and the production of hydrogen peroxide in water. The relation between the number of electrons injected from plasma in water and the number of H2O2 molecules was established and based on these results a scenario of reactions channels activated by plasma-water interface is concluded.

  1. Atmospheric Microplasma Application for Surface Modification of Biomaterials

    Science.gov (United States)

    Shimizu, Kazuo; Fukunaga, Hodaka; Tatematsu, Shigeki; Blajan, Marius

    2012-11-01

    Atmospheric microplasma has been intensively studied for applications in various fields, since in this technology the generated field is only 1 kV (approx) under atmospheric pressure and a dielectric barrier discharge gap of 10 to 100 µm. A low discharge voltage atmospheric plasma process is an economical and effective solution for various applications such as indoor air control including sterilization, odor removal, and surface treatment, and would be suitable for medical applications in the field of plasma life sciences. In this paper, we present the application of microplasma for the surface treatment of materials used in medical fields. Moreover, a biomaterial composed of L-lactic acid is used in experiments, which can be biodecomposed in the human body after medical operations. The surface modification process was carried out with active species generated between the microplasma electrodes, which were observed by emission spectrometry. Microplasma treatment of a polymer sheet using Ar as the process gas decreased the contact angle of a water droplet at the surface of the polymer from 78.3 to 45.6° in 10 s, indicating improved surface adhesive characteristics.

  2. Spatiotemporal Evolution of Ar(3P2) Metastable Density Generated in a Pulsed DC Atmospheric Pressure micro-Plasma Jet Impinging on a Glass Plate

    Science.gov (United States)

    Gazeli, K.; Bauville, G.; Es-Sebbar, Et-T.; Fleury, M.; Neveau, O.; Pasquiers, St.; Santos Sousa, J.; Laboratoire de Physique des gaz et des plasmas Team

    2016-09-01

    Atmospheric Pressure micro-Plasma Jets (APPJs) are promising tools in various domains such as biomedical and material treatments. In this work, APPJs are produced in pure argon at variable flow rates (i.e., 200, 400 and 600 sccm), by applying high voltage positive pulses (250 ns in FWHM and 6 kV in amplitude) at a repetition frequency of 20 kHz. The generated plasma impacts an ungrounded glass plate placed at a distance of 5 mm from the tube's orifice and perpendicular to the streamers propagation. At these conditions, a diffuse discharge is established resulting in a non-filamentary and reproducible plasma, in contrast with the free-jet case (no target). This allows the quantification of the absolute density of the Ar(1s5) metastable state by using laser absorption spectroscopy to probe the transition 1s5 -> 2p9 at 811.531 nm. The experiments show the dependence on the gas flow rate and on the axial and radial positions of the maximum density (6-9x1013 cm-3) . At 200 sccm, it is obtained close to the tube's orifice, while with increasing flow rate it is displaced towards the plate. Regarding the radial variation, density maxima are obtained in a small area around the streamers propagation axis.

  3. The mystery of O and O3 production in the effluent of a He/O2 atmospheric pressure microplasma jet

    CERN Document Server

    Ellerweg, Dirk; Benedikt, Jan

    2011-01-01

    Microplasma jets are commonly used to treat samples in ambient air atmosphere. The effect of admixing air into the effluent may severely affect the composition of the emerging species. Here, the effluent of a He/O2 microplasma jet has been analyzed in a helium and in an air atmosphere by molecular beam mass spectrometry. First, the composition of the effluent in air has been recorded as a function of the distance to determine how fast air admixes into the effluent. Then, the spatial distribution of atomic oxygen and ozone in the effluent has been recorded in ambient air and compared to measurements in a helium atmosphere. Additionally, a fluid model of the gas flow with reaction kinetics of reactive oxygen species in the effluent has been constructed. In ambient air, the O density declines only slightly faster with the distance compared to a helium atmosphere. On the contrary, the O3 density in ambient air increases significantly faster with the distance compared to a helium atmosphere. This mysterious behavi...

  4. Maskless Hydrophilic Patterning of the Superhydrophobic Aluminum Surface by an Atmospheric Pressure Microplasma Jet for Water Adhesion Controlling.

    Science.gov (United States)

    Liu, Jiyu; Song, Jinlong; Wang, Guansong; Chen, Faze; Liu, Shuo; Yang, Xiaolong; Sun, Jing; Zheng, Huanxi; Huang, Liu; Jin, Zhuji; Liu, Xin

    2018-02-19

    Superhydrophobic surfaces with hydrophilic patterns have great application potential in various fields, such as microfluidic systems and water harvesting. However, many reported preparation methods involve complicated devices and/or masks, making fabrication of these patterned surfaces time-consuming and inefficient. Here, we propose a highly efficient, simple, and maskless microplasma jet (MPJ) treatment method to prepare hydrophilic patterns such as dots, lines, and curves on superhydrophobic aluminum substrates. Contact angles, sliding angles, adhesive forces, and droplet impact behavior of the created patterns are investigated and analyzed. The prepared "dot" patterns exhibit great water adhesion, whereas the "line" patterns show anisotropic adhesion. Additionally, the MPJ treatment does not obviously change the surface structures, which makes it possible to achieve repeatable patterning on one substrate. The adhesion behavior of these patterns could be adjusted using MPJs with different diameters. MPJs with larger diameters are efficient for the creation of patterns with high water adhesion, which can be potentially used for open-channel lab-on-chip systems (e.g., continuous water transportation), whereas MPJs with smaller diameters are preferable in preparing patterns with low water adhesion for diverse applications in biomedical fields (e.g., lossless liquid droplet mixing and cell screening).

  5. Enhanced oxygen dissociation in a propagating constricted discharge formed in a self-pulsing atmospheric pressure microplasma jet

    Science.gov (United States)

    Schröder, Daniel; Burhenn, Sebastian; Kirchheim, Dennis; Schulz-von der Gathen, Volker

    2013-11-01

    We report on the propagation of a constricted discharge feature in a repetitively self-pulsing microplasma jet operated in helium with a 0.075 vol% molecular oxygen admixture in ambient air environment. The constricted discharge is about 1 mm in width and repetitively ignites at the point of smallest electrode distance in a wedge-shaped electrode configuration, propagates through the discharge channel towards the nozzle, extinguishes, and re-ignites at the inlet at frequencies in the kHz range. It co-exists with a homogeneous, volume-dominated low temperature (T ⋍ 300 K) α-mode glow. Time-resolved measurements of nitrogen molecule C-state and nitrogen molecule ion B-state emission bands reveal an increase of the rotational temperature within the constricted discharge to about 600 K within 50 µs. Its propagation velocity was determined by phase-resolved diagnostics to be similar to the gas velocity, in the order of 40 m s-1. Two-photon absorption laser-induced fluorescence spectroscopy synchronized to the self-pulsing reveals spatial regions of increased oxygen atom densities co-propagating with the constricted discharge feature. The generated oxygen pulse density is about ten times higher than in the co-existing homogeneous α-mode. Densities reach about 1.5 × 1016 cm-3 at average temperatures of 450 K at the nozzle. This enhanced dissociation of about 80% is attributed to the continuous interaction of the constricted discharge to the co-propagating gas volume.

  6. Low temperature atmospheric microplasma jet array for uniform treatment of polymer surface for flexible electronics

    Science.gov (United States)

    Wang, Tao; Wang, Xiaolin; Yang, Bin; Chen, Xiang; Yang, Chunsheng; Liu, Jingquan

    2017-07-01

    In this paper, the uniformity of polymer film etching by an atmospheric pressure He/O2 microplasma jet array (μPJA) is first investigated with different applied voltage. Plasma characteristics of μPJA were recorded by optical discharge images. Morphologies and chemical compositions of polymer film etched by μPJA were analyzed by optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS). By increasing the applied voltage from 8.5 kV to 16.4 kV, the non-uniformity of the luminous intensity of the plasma jets increases. It is interesting that the plasma treated regions are actually composed of an etched region and modification region, with distinct morphologies and chemical compositions. The diameters of the etched parylene-C film show the increase of non-uniformity with higher applied voltage. SEM results show that the non-uniformity of surface morphologies of both the modification regions and etched regions increases with the increase of applied voltage. EDS and XPS results also present the significant effect of higher applied voltage on the non-uniformity of surface chemical compositions of both modification and etched regions. The Coulomb interaction of the streamer heads and the hydrodynamic interaction between the plasma jets and the surrounding air are considered to be responsible for this phenomenon. The results shown in this work can help improve the processing quality of polymer film etched by an atmospheric pressure microplasma jet array and two applications are demonstrated to illustrate the uniform downstream surface treatment.

  7. Gas heating and plasma expansion in pulsed microwave-excited microplasmas

    Science.gov (United States)

    Hoskinson, Alan R.; Yared, Alexander; Hopwood, Jeffrey

    2015-10-01

    Microwave resonators are used to generate microplasmas in atmospheric-pressure argon and helium. We present observations of the transient behavior of a microplasma after a fast increase in power, including time-resolved photography and spectroscopic gas temperature measurements. The results show that in argon both plasma filamentation and gas heating continue out to millisecond time scales, while helium microplasmas reach steady-state conditions after a few microseconds.

  8. EDITORIAL: Cluster issue on microplasmas

    Science.gov (United States)

    Chao, Chih C.; Liao, Jiunn-Der; Chang, Juu-En

    2008-10-01

    Ever since the first Workshop on Microplasmas, held in Japan in 2003, plasma scientists and engineers worldwide have been meeting approximately every 18 months to exchange and discuss the results of scientific research and technical applications of this unique type of plasma. Microplasmas are generally described as stable plasmas confined to spatial dimensions below about 1 mm that can be operated at pressures up to and exceeding atmospheric pressure. By their nature, this presents a wide range of opportunities and many advantages in practical applications, just a few examples being low energy consumption, small size, flexibility of use and ease of assembly into a user-friendly package. Nevertheless, there still remain several unanswered basic science questions and a largely untapped potential for environmental, biomedical and industrial applications. The fourth International Workshop on Microplasmas, held during 28-31 October 2007 in Tainan, Taiwan, continued the trend of previous Workshops with an orientation towards industrial and environmental applications. Many high-quality papers on microplasmas and microdischarges were presented and selected full papers were submitted to Journal of Physics D: Applied Physics for assessment by the editors and reviewers in accordance with the usual standards of quality and novelty. This Cluster Issue contains twelve accepted papers, covering four categories: fundamentals and basics, and environmental, biomedical and industrial applications. Fundamentals and basics includes coverage of the physics and microstructure of electrode discharge (Yu A Lebedev et al), the characteristics of low current discharge (Z Lj Petrović et al), plasma ignition (R Gesche et al), novel optical diagnostics (Schulz-von der Gathen et al), plasma generation and micronozzle flow (T Takahashi et al) and the relation between RF-power and atomic oxygen density distribution (N Knake et al). Environmental applications are represented by vapour

  9. Microplasma generator and methods therefor

    Energy Technology Data Exchange (ETDEWEB)

    Hopwood, Jeffrey A

    2015-04-14

    A low-temperature, atmospheric-pressure microplasma generator comprises at least one strip of metal on a dielectric substrate. A first end of the strip is connected to a ground plane and the second end of the strip is adjacent to a grounded electrode, with a gap being defined between the second end of the strip and the grounded electrode. High frequency power is supplied to the strip. The frequency is selected so that the length of the strip is an odd integer multiple of 1/4 of the wavelength traveling on the strip. A microplasma forms in the gap between the second end of the strip and the grounded electrode due to electric fields in that region. A microplasma generator array comprises a plurality of strongly-coupled resonant strips in close proximity to one another. At least one of the strips has an input for high-frequency electrical power. The remaining strips resonate due to coupling from the at least one powered strip. The array can provide a continuous line or ring of plasma. The microplasma generator can be used to alter the surface of a substrate, such as by adding material (deposition), removal of material (etching), or modifying surface chemistry.

  10. Spatially resolved spectroscopy and electrical characterization of microplasmas and switchable microplasma arrays

    Science.gov (United States)

    Hoskinson, Alan R.; Hopwood, Jeffrey

    2014-02-01

    Microwave resonators are used to generate microplasmas in atmospheric-pressure argon. We present spectroscopic and electrical measurements of these microplasmas for both a single resonator and a five-element resonator array with dc voltage-switchable power distribution. These measurements include gas temperatures from fits to rotational emission spectra and electron densities from Stark broadening, both resolved in two spatial dimensions. Peak gas temperatures are found to be near 900 K in the centre of the microplasmas, while electron densities peak near 3 × 1014 cm-3. Spectroscopically derived plasma densities are validated by comparison with electrical measurements of the complex plasma impedances. The plasma impedances shift the resonant frequencies and quality factors of the individual resonators, which in turn influence power distribution to the resonators. Data suggest that this feedback loop reinforces the electrical switching mechanism.

  11. Use of thermocouples and argon line broadening for gas temperature measurement in a radio frequency atmospheric microplasma jet

    Science.gov (United States)

    Doyle, S. J.; Xu, K. G.

    2017-02-01

    This paper presents the use of thermocouples and line broadening of argon 2p-1s emission lines for the measurement of gas temperature of an atmospheric argon microplasma jet. The measured temperatures are compared with rotational spectra fitting of OH (A-X) and N2 (C-B) emission. An rf microplasma jet with two electrical configurations and different temperature ranges was used. The calculated gas temperatures with thermocouples, argon lines, and OH ranged from 290 to 423 K and 393-510 K for the two configurations, depending on the rf power. The temperature from fitting the N2 spectra overestimated the gas temperatures in both configurations (593-680 and 664-853 K). The non-nitrogen temperature measurements agree well with each other within the measurement uncertainty. The results show that not all optical emission temperature methods are appropriate and the accuracy of argon line broadening is dependent on the device configuration. The results also show that conventional thermocouples are surprisingly accurate and viable for these plasmas.

  12. Investigation of Microplasma Instabilities at 1 GHz

    Science.gov (United States)

    Wu, Chen; Hopwood, Jeffrey

    2013-09-01

    Microwave microplasmas have been operated stably in excess of 2000 hours using less than one watt of power. Plasmas at atmospheric pressure and high power density, however, are subject to ionization overheating instability followed by a destructive glow-to-arc transition. We describe steady-state atmospheric pressure microplasmas in non-flowing argon and air driven by up to 40 watts of microwave power. These discharges are supported by either a quarter-wave microstrip resonator or a microstrip transmission line. Models show that the resonator configuration rejects excess power and remains unconditionally stable. The transmission line, however, couples power efficiently to a plasma of ~100 Ω and produces a more intense discharge. Electrodes of copper, aluminum and lead-based solder are investigated on both polymer and alumina substrates. Copper and lead electrodes may be evaporated by a high power microdischarge as seen by optical emission. These conditions uniquely result in severe electrode damage. Microdischarges supported on polymer substrates show C2, CN and CH emission but alumina substrates are unaffected by the microplasma. These results show that steady-state microwave discharges can be stable at very high power density provided that copper microelectrodes and ceramic substrates are employed. This work supported by the US DOE Grant No. DE-SC0001923.

  13. Design, modeling, and diagnostics of microplasma generation at microwave frequency

    Science.gov (United States)

    Miura, Naoto

    Plasmas are partially ionized gases that find wide utility in the processing of materials, especially in integrated circuit fabrication. Most industrial applications of plasma occur in near-vacuum where the electrons are hot (>10,000 K) but the gas remains near room temperature. Typical atmospheric plasmas, such as arcs, are hot and destructive to sensitive materials. Recently the emerging field of microplasmas has demonstrated that atmospheric ionization of cold gases is possible if the plasma is microscopic. This dissertation investigates the fundamental physical properties of two classes of microplasma, both driven by microwave electric fields. The extension of point-source microplasmas into a line-shaped plasma is also described. The line-shape plasma is important for atmospheric processing of materials using roll-coating. Microplasma generators driven near 1 GHz were designed using microstrip transmission lines and characterized using argon near atmospheric pressure. The electrical characteristics of the microplasma including the discharge voltage, current and resistance were estimated by comparing the experimental power reflection coefficient to that of an electromagnetic simulation. The gas temperature, argon metastable density and electron density were obtained by optical absorption and emission spectroscopy. The microscopic internal plasma structure was probed using spatially-resolved diode laser absorption spectroscopy of excited argon states. The spatially resolved diagnostics revealed that argon metastable atoms were depleted within the 200mum core of the microplasma where the electron density was maximum. Two microplasma generators, the split-ring resonator (SRR) and the transmission line (T-line) generator, were compared. The SRR ran efficiently with a high impedance plasma (>1000 O) and was stabilized by the self-limiting of absorbed power (<1W) as a lower impedance plasma caused an impedance mismatch. Gas temperatures were <1000 K and electron

  14. Instability control in microwave-frequency microplasma

    Science.gov (United States)

    Miura, N.; Hopwood, J.

    2012-05-01

    Atmospheric argon microplasmas driven by 1.0 GHz power were studied by microwave circuit analyses and spatially-resolved optical diagnostics. These studies illuminate the mechanisms responsible for microplasma stability. A split-ring resonator (SRR) microplasma source is demonstrated to reflect excess microwave power, preventing the ionization overheating instability while limiting electron density to approximately 1 × 1014 cm-3 and OH rotational temperature to 760 K at 0.76 W. Providing the SRR microplasma with an electrical path to ground, however, allows the microplasma to transition from the SRR mode to the so-called transmission line mode (T-line). This transition is due to matching of the microplasma and transmission line impedances. The higher power T-line mode supports a more intense microplasma with electron density of 1 × 1015 cm-3 and OH rotational temperature of 1480 K with 15 W absorbed power. While the SRR mode is optimized for ignition and sustaining a stable nonequilibrium plasma, and T-line mode is better suited for driving a hot, high density microplasma. The estimated microwave discharge voltages were 15 V and 35 V in SRR mode and T-line mode, respectively, and the voltages are rather independent of input power. Microplasma stability is due to a combination of impedance mismatching and direct control of power, both inherent to microwave circuitry.

  15. Water Purification by Using Microplasma Treatment

    Science.gov (United States)

    Shimizu, K.; Masamura, N.; Blajan, M.

    2013-06-01

    Dielectric barrier discharge microplasma generated at the surface of water is proposed as a solution for water treatment. It is an economical and an ecological technology for water treatment due to its generation at atmospheric pressure and low discharge voltage. Microplasma electrodes were placed at small distance above the water thus active species and radicals were flown by the gas towards the water surface and furthermore reacted with the target to be decomposed. Indigo carmine was chosen as the target to be decomposed by the effect of active species and radicals generated between the electrodes. Air, oxygen, nitrogen and argon were used as discharge gases. Measurement of absorbance showed the decomposition of indigo carmine by microplasma treatment. Active species and radicals of oxygen origin so called ROS (reactive oxidative species) were considered to be the main factor in indigo carmine decomposition. The decomposition rate increased with the increase of the treatment time as shown by the spectrophotometer analysis. Discharge voltage also influenced the decomposition process.

  16. On-chip microplasma reactors using carbon nanofibres and tungsten oxide nanowires as electrodes

    NARCIS (Netherlands)

    Agiral, A.; Groenland, A.W.; Chinthaginjala, J.K.; Kumar Chinthaginjala, J.; Seshan, Kulathuiyer; Lefferts, Leonardus; Gardeniers, Johannes G.E.

    2008-01-01

    Carbon nanofibres (CNFs) and tungsten oxide (W18O49) nanowires have been incorporated into a continuous flow type microplasma reactor to increase the reactivity and efficiency of the barrier discharge at atmospheric pressure. CNFs and tungsten oxide nanowires were characterized by high-resolution

  17. 3D-printed, sugar cube-size microplasma on a hybrid chip used as a spectral lamp to characterize UV-Vis transmission characteristics of polycarbonate chips for microfluidic applications

    Science.gov (United States)

    Devathasan, D.; Trebych, K.; Karanassios, Vassili

    2013-05-01

    A 3d-printed, solar-powered, battery-operated, atmospheric-pressure, self-igniting microplasma the size of a sugar-cube has been used as light source to document the Ultra Violet (UV) and visible transmission characteristics of differentthickness polycarbonate chips that are often used for microfluidic applications. The hybrid microplasma chip was fitted with a quartz plate because quartz is transparent to UV.

  18. Study of microplasmas from GHz to THz

    Science.gov (United States)

    Gregório, José; Hoskinson, Alan R.; Parsons, Stephen; Hopwood, Jeffrey

    2015-09-01

    We present a study of atmospheric-pressure microplasmas sustained from 0.5 GHz to 0.5 THz with continuous excitation frequencies. A fluid model shows the existence of electron plasma resonances in a highly collisional microplasma. At 0.5 GHz the behavior is similar to a typical rf collisional discharge. As frequency increases at constant power density we observe a decrease in the discharge voltage from greater than 100 volts to less than 10 volts. This minimum voltage amplitude is attained when electron temporal inertia delays the discharge current to be in phase with the applied voltage. Above this frequency the plasma develops resonant regions where the excitation frequency equals the local plasma frequency. In these volumes the instantaneous quasi-neutrality is perturbed and intense internal currents emerge ensuring a low voltage operation range. This enhanced plasma heating mechanism vanishes when the excitation frequency is larger than the local plasma frequency everywhere in the plasma volume. For a typical peak electron density of 5 ×1020 m-3 this condition corresponds to ~ 0.2 THz.

  19. Microplasma copolymerization of amine and Si containing precursors

    Energy Technology Data Exchange (ETDEWEB)

    Bashir, M., E-mail: m.bashir@comsats.edu.pk [Department of Chemical and Biological Engineering and Kroto Research Institute, University of Sheffield, Sheffield S1 3JD (United Kingdom); Rees, Julia M.; Bashir, S. [School of Mathematics and Statistics, Hicks Building, Hounsfield Road, University of Sheffield, S3 7RH (United Kingdom); Zimmerman, William B. [Department of Chemical and Biological Engineering and Kroto Research Institute, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2014-08-01

    We report a technique of microplasma copolymerization for depositing a stable amino functional film on the inner walls of a glass microcapillary. The monomers ethylenediamine (EDA), 3 aminopropyltriethoxysilane (APTS) and hexamethyldisiloxane (HMDSO) were used as organic precursors for copolymerization. The ratio of the monomer mixture in the plasma was precisely fed using an original technique of liquid injection and helical mixing. The coatings obtained from EDA–HMDSO were found to be more stable than those produced using EDA and APTS. The films were characterized using X-ray photoelectron, Fourier transform infrared and UV–vis spectroscopy, atomic force microscopy and growth rate measurements. The hydrophobic and hydrophilic characteristics of the films were analyzed through water contact angle and surface free energy measurements. The stability of the coatings formed using this method in aqueous media indicated that they could be utilized for biological and microfluidic applications. - Highlights: • An atmospheric pressure microplasma was generated in a rectangular glass capillary. • Surface coating of capillary was performed using microplasma copolymerization. • Monomer ratios were manipulated via liquid injection and helical mixing. • Films were studied in detail using standard characterization techniques. • The stability of the coating was observed by immersing the films in deionized water.

  20. Synergistic Effect of Atmospheric-pressure Plasma and TiO2 Photocatalysis on Inactivation of Escherichia coli Cells in Aqueous Media

    Science.gov (United States)

    Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Li, Jiangwei; Wang, Xingquan; Chen, Qiang; Yang, Size; Chen, Zhong; Bazaka, Kateryna; (Ken) Ostrikov, Kostya

    2016-01-01

    Atmospheric-pressure plasma and TiO2 photocatalysis have been widely investigated separately for the management and reduction of microorganisms in aqueous solutions. In this paper, the two methods were combined in order to achieve a more profound understanding of their interactions in disinfection of water contaminated by Escherichia coli. Under water discharges carried out by microplasma jet arrays can result in a rapid inactivation of E. coli cells. The inactivation efficiency is largely dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2, He and air microplasma arrays, O2 microplasma had the highest activity against E. coli cells in aqueous solution, and showed >99.9% bacterial inactivation efficiency within 4 min. Addition of TiO2 photocatalytic film to the plasma discharge reactor significantly enhanced the inactivation efficiency of the O2 microplasma system, decreasing the time required to achieve 99.9% killing of E. coli cells to 1 min. This may be attributed to the enhancement of ROS generation due to high catalytic activity and stability of the TiO2 photocatalyst in the combined plasma-TiO2 systems. Present work demonstrated the synergistic effect of the two agents, which can be correlated in order to maximize treatment efficiency. PMID:28004829

  1. Argon metastable production in argon-helium microplasmas

    Science.gov (United States)

    Hoskinson, Alan R.; Gregorío, José; Hopwood, Jeffrey; Galbally-Kinney, Kristin; Davis, Steven J.; Rawlins, Wilson T.

    2016-06-01

    Microwave resonator-driven microplasmas are a promising technology for generating the high density of rare-gas metastable states required for optically pumped rare gas laser systems. We measure the density of argon 1s5 states (Paschen notation) in argon-helium plasmas between 100 Torr and atmospheric pressure using diode laser absorption. The metastable state density is observed to rise with helium mole fraction at lower pressures but to instead fall slightly when tested near atmospheric pressure. A 0-D model of the discharge suggests that these distinct behaviors result from the discharge being diffusion-controlled at lower pressures, but with losses occurring primarily through dissociative recombination at high pressures. In all cases, the argon metastable density falls sharply when the neutral argon gas fraction is reduced below approximately 2%.

  2. MicroScale - Atmospheric Pressure Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, Mohan [Case Western Reserve University

    2012-01-25

    Low-temperature plasmas play an essential role in the manufacturing of integrated circuits which are ubiquitous in modern society. In recent years, these top-down approaches to materials processing have reached a physical limit. As a result, alternative approaches to materials processing are being developed that will allow the fabrication of nanoscale materials from the bottom up. The aim of our research is to develop a new class of plasmas, termed “microplasmas” for nanomaterials synthesis. Microplasmas are a special class of plasmas formed in geometries where at least one dimension is less than 1 mm. Plasma confinement leads to several unique properties including high-pressure stability and non-equilibrium that make microplasams suitable for nanomaterials synthesis. Vapor-phase precursors can be dissociated to homogeneously nucleate nanometer-sized metal and alloyed nanoparticles. Alternatively, metal salts dispersed in liquids or polymer films can be electrochemically reduced to form metal nanoparticles. In this talk, I will discuss these topics in detail, highlighting the advantages of microplasma-based systems for the synthesis of well-defined nanomaterials.

  3. Microwave harmonic generation and nonlinearity in microplasmas

    Science.gov (United States)

    Gregório, José; Parsons, Stephen; Hopwood, Jeffrey

    2016-06-01

    Nonlinearities in microplasmas excited by microwaves are described both experimentally and through a 2D fluid model. A split-ring resonator generates a microplasma in a 150 μm discharge gap at 1 GHz. Nonlinearity generates both radiated and conducted harmonics which are measured from 0.2-760 Torr (Ar) for power levels between 0.5 and 3 W. Asymmetric electrode configurations produce the highest 3rd harmonic power (>10 mW) at an optimal pressure of the order of 0.3 Torr. The microplasma is also demonstrated as a mixer. The experimental results are explained with the aid of a fluid model of the microplasma. The model shows that the smaller electrode in an asymmetric device is forced to attain a large microwave potential that strongly modulates the sheath thickness and the local electron energy. The voltage-dependent sheath width gives rises to a nonlinear sheath capacitance as well as short pulses of hot electron flux to the electrode. The modeled 3rd harmonic current is converted to an extractable harmonic power by a microwave circuit model. Using this technique the modeled and measured harmonic production of the microplasma are found to compare favorably.

  4. Atmospheric-pressure plasma technology

    Science.gov (United States)

    Kogelschatz, U.

    2004-12-01

    Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona discharges used in electrostatic precipitators and in dielectric-barrier discharges used for generation of ozone, for pollution control and for surface treatment. More recent applications include UV excimer lamps, mercury-free fluorescent lamps and flat plasma displays.

  5. Generation of Energetic Species by RF Microplasma Arrays

    Science.gov (United States)

    Rawlins, W. T.; Lee, S.; Fenner, D. B.; Davis, S. J.; Hoskinson, A. R.; Hopwood, J.

    2012-10-01

    We present preliminary results from the first implementation of a prototype single-board RF micro-discharge, linear array device in a discharge-flow reactor for quantitative determinations of ozone and singlet-oxygen production from microplasmas in O2 and air at 1 atm. The ultimate objective is to develop compact, portable low-power micro-discharge based systems to generate energetic species for atmospheric-pressure applications including decontamination and disinfection. The technology uses application of low DC voltages and low applied powers (˜25 W) at ˜1 GHz frequencies, across small gaps in arrays of resonators to ignite and sustain highly energetic microplasmas at elevated pressures. A set of 15-resonator micro-discharge assemblies was designed, fabricated, and tested in static and flowing environments for O2, air, and Ar flows at pressures of 20 Torr to 1 atm. O3 production was measured by UV absorption spectrometry, and O2(a^1delta-g) (``singlet-oxygen'') concentrations were determined by absolute near-infrared emission spectroscopy. Near-infrared emission spectra from an argon plasma were also recorded, and showed extensive excitation of the Ar(I) 3p^54p -- 3p^54s emission system near 12 eV.

  6. Fundamental Scaling of Microplasmas and Tunable UV Light Generation.

    Energy Technology Data Exchange (ETDEWEB)

    Manginell, Ronald P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hopkins, Matthew M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yee, Benjamin Tong [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moorman, Matthew W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schwindt, Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, John Moses [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pfeifer, Nathaniel Bryant [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    The temporal evolution of spectral lines from microplasma devices (MD) was studied, including impurity transitions. Long-wavelength emission diminishes more rapidly than deep UV with decreasing pulse width and RF operation. Thus, switching from DC to short pulsed or RF operation, UV emissions can be suppressed, allowing for real-time tuning of the ionization energy of a microplasma photo-ionization source, which is useful for chemical and atomic physics. Scaling allows MD to operate near atmospheric pressure where excimer states are efficiently created and emit down to 65 nm; laser emissions fall off below 200 nm, making MD light sources attractive for deep UV use. A first fully-kinetic three-dimensional model was developed that explicitly calculates electron-energy distribution function. This, and non-continuum effects, were studied with the model and how they are impacted by geometry and transient or DC operation. Finally, a global non-dimensional model was developed to help explain general trends MD physics.

  7. Determining Atmospheric Pressure Using a Water Barometer

    Science.gov (United States)

    Lohrengel, C. Frederick, II; Larson, Paul R.

    2012-01-01

    The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

  8. Study of structural modification of sugarcane bagasse employing hydrothermal treatment followed by atmospheric pressure plasmas treatment

    Science.gov (United States)

    Amorim, Jayr; Pimenta, Maria Teresa; Gurgel, Leandro; Squina, Fabio; Souza-Correa, Jorge; Curvelo, Antonio

    2009-10-01

    Nowadays, the cellulosic ethanol is an important alternative way to many liquid biofuels using renewable biomass rich in polysaccharides. To be used as feedstock for ethanol production, the bagasse needs to be pretreated in order to expose its main constitutive. The present work proposes the use of different pretreatment processes to better expose the cellulose for hydrolysis and fermentation. In the present paper the sugarcane bagasse was submitted to a hydrothermal pretreatment followed by atmospheric pressure plasmas (APPs). An RF microplasma torch was employed as APPs in Ar and Ar/O2 mixing. The bagasse was treated in discharge and post-discharge regions. The position and time of treatment was varied as well as the gas mixture. The quantity of polysaccharides was determined by using high performance liquid chromatography. It was observed the release of a fraction of the hemicelluloses in the sugarcane bagasse. Modifications in the surface of the sugarcane fibers were monitored by employing scanning electron microscopy.

  9. Atmospheric pressure plasma jet applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.; Herrmann, H.W.; Henins, I.; Selwyn, G.S. [Los Alamos National Lab., NM (United States)

    1998-12-31

    The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O) which flows between two concentric cylindrical electrodes: an outer grounded electrode and an inner electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas becomes excited, ionized or dissociated by electron impact. The fast-flowing effluent consists of ions and electrons, which are rapidly lost by recombination, highly reactive radicals (e.g., O, OH), and metastable species (e.g., O2). The metastable O2, which is reactive to hydrocarbon and other organic species, has been observed through optical emission spectroscopy to decrease by a factor of 2 from the APPJ nozzle exit to a distance of 10 cm. Unreacted metastable O2, and that which does not impinge on a surface, will then decay back to ordinary ground state O2, resulting in a completely dry, environmentally-benign form of surface cleaning. Applications such as removal of photoresist, oxide films and organic residues from wafers for the electronics industry, decontamination of civilian and military areas and personnel exposed to chemical or biological warfare agents, and paint (e.g., graffiti) removal are being considered.

  10. Microplasmas and micro-jets

    Science.gov (United States)

    Lazzaroni, C.; Aubert, X.; Marinov, D.; Guaitella, O.; Stancu, G.; Welzel, S.; Pipa, A.; Ropcke, J.; Sadeghi, N.; Rousseau, A.

    2008-07-01

    Microplasmas are now widely investigated, one of their advantages being to generate a plasma at relatively high pressure close to the Paschen minimum (Schoenbach et al. 1997). Here, the microplasma is generated in a microhollow cathode type configuration made of a hole drilled through a metal/dielectric/metal sandwich (Schoenbach et al. 1997). One of the electrodes acts as the cathode (K) and the other as the anode (A1). The hole diameter ranges from 100 to 400 mu m and the pressure ranges from 50 to 500 Torr. When a second electrode (A2) is added, a large volume of plasma plume may be generated between A1 and A2, at a low electric field (1-20Td depending upon the gas) (Stark et al. 1999). A microhollow cathode type discharge operates in three different regimes depending on the plasma current: abnormal, self-pulsing and normal regime. The self-pulsing regime is achieved in the range of 1-100 kHz, in argon, helium, nitrogen and oxygen. The self-pulsing frequency is controlled by the microplasma device capacitance, the gas breakdown voltage, and the average discharge current (Rousseau et al. 2006, Aubert et al. 2007). i) First, in pure argon, the radial dependence of atoms excitation mechanisms and of the electronic density is studied inside the micro-hole. Imaging of the emission from the microplasma is performed with a spatial resolution of few mu m. The electron density is estimated from the Stark broadening of the H beta-line. The radial distribution of the emission intensities of an Ar atomic line and an Ar^+ ionic line are used for the excitation study. Ar and Ar^+ lines are excited in the cathode sheath edge by beam electrons accelerated within the sheath. These two excitations show the decay of the energy of electrons in negative glow. The Ar line presents also production of excited atoms by recombination of argon ions with electrons at the center of the micro-hole.Work is in progress to evaluate the contribution of the static electric field on the strak

  11. Microplasma sprayed hydroxyapatite coatings

    CERN Document Server

    Dey, Arjun

    2015-01-01

    ""This unique book on development of microplasma sprayed HAp coating has been organized in a very compact yet comprehensive manner. This book also highlights the horizons of future research that invites the attention of global community, particularly those in bio-medical materials and bio-medical engineering field. This book will surely act as a very useful reference material for both graduate/post-graduate students and researchers in the field of biomedical, orthopedic and manufacturing engineering and research. I truly believ that this is the first ever effort which covers almost all the

  12. Photoionization microplasma sensor

    Science.gov (United States)

    Mustafaev, A. S.; Rastvorova, I. V.; Podenko, S. S.; Tsyganov, A. B.

    2017-11-01

    New developments in the physics of plasma are presented, specifically, research of completely new method of atoms’ and molecules’ detection in gaseous phase – collisional electron spectroscopy. As a result, the microplasma sensor for quality and quantity analysis of the gaseous mixture was created. It works in the discharge afterglow mode using He as a buffer gas. In addition, the modification of the sensor using resonance photon photoionization was developed. This consideration gives the opportunity for wide practical appliance as an individual gas analyzer for industrial and medical purposes.

  13. An Atmospheric Pressure Ping-Pong ``Ballometer''

    Science.gov (United States)

    Kazachkov, Alexander; Kryuchkov, Dmitriy; Willis, Courtney; Moore, John C.

    2006-11-01

    Classroom experiments on atmospheric pressure focus largely on demonstrating its existence, often in a most impressive way. A series of amusing physics demonstrations is widely known and practiced by educators teaching the topic. However, measuring the value of atmospheric pressure (Patm) is generally done in a rather mundane way, simply by reading some commercially produced meter. Even though students building a 35-ft high water barometer1,2 is definitely instructive, as is the measurement of Patm with much smaller gas-filled devices,3,4 there exist hardly any physics lab exercises focused on the measurement of atmospheric pressure. This paper describes a modification of a well-known physics demonstration into an experiment that allows one to estimate atmospheric pressure quite accurately. Our simple and inexpensive apparatus can be used in lecture demonstrations or as a tool in an educational laboratory setting.

  14. Low Temperature Atmospheric Pressure Plasma Sterilization Shower

    Science.gov (United States)

    Gandhiraman, R. P.; Beeler, D.; Meyyappan, M.; Khare, B. N.

    2012-10-01

    Low-temperature atmospheric pressure plasma sterilization shower to address both forward and backward biological contamination issues is presented. The molecular effects of plasma exposure required to sterilize microorganisms is also analysed.

  15. Evaporation of urea at atmospheric pressure.

    Science.gov (United States)

    Bernhard, Andreas M; Czekaj, Izabela; Elsener, Martin; Wokaun, Alexander; Kröcher, Oliver

    2011-03-31

    Aqueous urea solution is widely used as reducing agent in the selective catalytic reduction of NO(x) (SCR). Because reports of urea vapor at atmospheric pressure are rare, gaseous urea is usually neglected in computational models used for designing SCR systems. In this study, urea evaporation was investigated under flow reactor conditions, and a Fourier transform infrared (FTIR) spectrum of gaseous urea was recorded at atmospheric pressure for the first time. The spectrum was compared to literature data under vacuum conditions and with theoretical spectra of monomolecular and dimeric urea in the gas phase calculated with the density functional theory (DFT) method. Comparison of the spectra indicates that urea vapor is in the monomolecular form at atmospheric pressure. The measured vapor pressure of urea agrees with the thermodynamic data obtained under vacuum reported in the literature. Our results indicate that considering gaseous urea will improve the computational modeling of urea SCR systems.

  16. Selective neuronal differentiation of neural stem cells induced by nanosecond microplasma agitation

    Directory of Open Access Journals (Sweden)

    Z. Xiong

    2014-03-01

    Full Text Available An essential step for therapeutic and research applications of stem cells is their ability to differentiate into specific cell types. Neuronal cells are of great interest for medical treatment of neurodegenerative diseases and traumatic injuries of central nervous system (CNS, but efforts to produce these cells have been met with only modest success. In an attempt of finding new approaches, atmospheric-pressure room-temperature microplasma jets (MPJs are shown to effectively direct in vitro differentiation of neural stem cells (NSCs predominantly into neuronal lineage. Murine neural stem cells (C17.2-NSCs treated with MPJs exhibit rapid proliferation and differentiation with longer neurites and cell bodies eventually forming neuronal networks. MPJs regulate ~75% of NSCs to differentiate into neurons, which is a higher efficiency compared to common protein- and growth factors-based differentiation. NSCs exposure to quantized and transient (~150 ns micro-plasma bullets up-regulates expression of different cell lineage markers as β-Tubulin III (for neurons and O4 (for oligodendrocytes, while the expression of GFAP (for astrocytes remains unchanged, as evidenced by quantitative PCR, immunofluorescence microscopy and Western Blot assay. It is shown that the plasma-increased nitric oxide (NO production is a factor in the fate choice and differentiation of NSCs followed by axonal growth. The differentiated NSC cells matured and produced mostly cholinergic and motor neuronal progeny. It is also demonstrated that exposure of primary rat NSCs to the microplasma leads to quite similar differentiation effects. This suggests that the observed effect may potentially be generic and applicable to other types of neural progenitor cells. The application of this new in vitro strategy to selectively differentiate NSCs into neurons represents a step towards reproducible and efficient production of the desired NSC derivatives.

  17. Peering inside microplasmas sustained by microwaves, millimeter waves and beyond

    Science.gov (United States)

    Hopwood, Jeffrey

    2016-09-01

    Atmospheric microplasmas are experimentally investigated over a range of excitation frequency from 0.5 to 12 GHz. A validated fluid model correctly predicts the measured electron density in this band of operation. This model is then extended to predict plasma behavior up to 0.4 THz. At constant power (0.25 W), the central electron density increases to 5x1014 cm-3 as the microwave frequency increases toward the electron energy dissipation frequency of 5 GHz (in argon). Above 5 GHz, the argon plasma density remains approximately constant, but the electrode voltage decreases to less than 5 volts in amplitude. This is remarkable in that the microwave potential is less than the excitation potential of argon. In the millimeter wave band, we observe series resonance between the plasma inductance and sheath capacitance at 30 GHz. The parallel resonance results in strong electron oscillation within the microplasma at the position where the electron plasma frequency is equal to the excitation frequency ( 200 GHz). Crossing resonance boundaries changes the nature of the microplasma impedance between capacitive, resistive, and inductive. In addition to linear behavior, we also present models and measurements of microplasma nonlinearity. Nonlinearity generates harmonic plasma currents and is due primarily to dynamic sheath expansion and electron conduction currents. In total, the microplasma provides a rich variety of electromagnetic behaviors that can be incorporated into plasma-reconfigurable metamaterials and photonic crystals. This work was supported by the Air Force Office of Scientific Research under Award No. FA9550-14-10317 with Dr. Mitat Birkan as the program manager.

  18. Atmospheric pressure femtosecond laser imaging mass spectrometry

    Science.gov (United States)

    Coello, Yves; Gunaratne, Tissa C.; Dantus, Marcos

    2009-02-01

    We present a novel imaging mass spectrometry technique that uses femtosecond laser pulses to directly ionize the sample. The method offers significant advantages over current techniques by eliminating the need of a laser-absorbing sample matrix, being suitable for atmospheric pressure sampling, and by providing 10μm resolution, as demonstrated here with a chemical image of vegetable cell walls.

  19. Numerical study of the influence of surface reaction probabilities on reactive species in an rf atmospheric pressure plasma containing humidity

    Science.gov (United States)

    Schröter, Sandra; Gibson, Andrew R.; Kushner, Mark J.; Gans, Timo; O’Connell, Deborah

    2018-01-01

    The quantification and control of reactive species (RS) in atmospheric pressure plasmas (APPs) is of great interest for their technological applications, in particular in biomedicine. Of key importance in simulating the densities of these species are fundamental data on their production and destruction. In particular, data concerning particle-surface reaction probabilities in APPs are scarce, with most of these probabilities measured in low-pressure systems. In this work, the role of surface reaction probabilities, γ, of reactive neutral species (H, O and OH) on neutral particle densities in a He–H2O radio-frequency micro APP jet (COST-μ APPJ) are investigated using a global model. It is found that the choice of γ, particularly for low-mass species having large diffusivities, such as H, can change computed species densities significantly. The importance of γ even at elevated pressures offers potential for tailoring the RS composition of atmospheric pressure microplasmas by choosing different wall materials or plasma geometries.

  20. Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

    Science.gov (United States)

    Kelly, Seán; Golda, Judith; Turner, Miles M.; Schulz-von der Gathen, Volker

    2015-11-01

    Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration.

  1. Characterization of rapidly-prototyped, battery-operated, argon-hydrogen microplasma on a hybrid chip for elemental analysis of microsamples by portable optical emission spectrometry

    Science.gov (United States)

    Weagant, Scott; Dulai, Gurjit; Li, Lu; Karanassios, Vassili

    2015-04-01

    A rapidly-prototyped, battery-operated, atmospheric-pressure, self-igniting Ar-H2 microplasma was interfaced to a portable fiber-optic spectrometer. The microplasma-spectrometer combination was used to document the spectral lines emitted when μL of dilute solutions of single element standards of Ag, Ba, Ca, Eu, Pd, Rb and Sr were first dried and then vaporized into the microplasma. A small-size, electrothermal vaporization system was used for microsample introduction. Identification of the prominent spectral lines for these elements is reported. It was found that the most prominent spectral line for Ba, Ca and Sr was different than that emitted from an inductively coupled plasma (ICP). In general, prominent spectral lines with low excitation energy were dominating, thus resulting in spectra simpler than those emitted from an ICP. Detection limits were between 45 and 180 pg (expressed in absolute amounts). When expressed in relative concentration units, they ranged between 15 and 60 μg/L (obtained using 3 μL diluted standards). Calibration curves were linear (on the average) for 1.5 orders-of-magnitude. Average precision was 15%. Analytical capability and utility was demonstrated using the determination of Ca and Mg in (medicinal) thermal spring water.

  2. Martian Atmospheric Pressure Static Charge Elimination Tool

    Science.gov (United States)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  3. Battery-operated, argon-hydrogen microplasma on hybrid, postage stamp-sized plastic-quartz chips for elemental analysis of liquid microsamples using a portable optical emission spectrometer.

    Science.gov (United States)

    Weagant, Scott; Chen, Vivian; Karanassios, Vassili

    2011-11-01

    A battery-operated, atmospheric pressure, self-igniting, planar geometry Ar-H(2) microplasma for elemental analysis of liquid microsamples is described. The inexpensive microplasma device (MPD) fabricated for this work was a hybrid plastic-quartz structure that was formed on chips with an area (roughly) equal to that of a small-sized postage stamp (MPD footprint, 12.5-mm width by 38-mm length). Plastic substrates were chosen due to their low cost, for rapid prototyping purposes, and for a speedy microplasma device evaluation. To enhance portability, the microplasma was operated from an 18-V rechargeable battery. To facilitate portability even further, it was demonstrated that the battery can be recharged by a portable solar panel. The battery-supplied dc voltage was converted to a high-voltage ac. The ~750-μm (diameter) and 12-mm (long) Ar-H(2) (3% H(2)) microplasma was formed by applying the high-voltage ac between two needle electrodes. Spectral interference from the electrode materials or from the plastic substrate was not observed. Operating conditions were found to be key to igniting and sustaining a microplasma that was simply "warm" to the touch (thus alleviating the need for cooling or other thermal management) and that had a stable background emission. A small-sized (900 μL internal volume) electrothermal vaporization system (40-W max power) was used for microsample introduction. Microplasma background emission in the spectral region between 200 and 850 nm obtained using a portable fiber-optic spectrometer is reported and the effect of the operating conditions is described. Analyte emission from microliter volumes of dilute single-element standard solutions of Cd, Cu, K, Li, Mg, Mn, Na, Pb, and Zn is documented. The majority of spectral lines observed for the elements tested were from neutral atoms. The relative lack of emission from ion lines simplified the spectra, thus facilitating the use of a portable spectrometer. Despite the relative spectral

  4. Microplasmas, a platform technology for a plethora of plasma applications

    Science.gov (United States)

    Becker, Kurt

    2017-08-01

    Publications describing microplasmas, which are commonly defined as plasmas with at least one dimension in the submillimeter range, began to appear to the scientific literature about 20 years ago. As discussed in a recent review by Schoenbach and Becker [1], interest and activities in basic microplasma research as well as in the use of microplasma for a variety of application has increased significatly over the past 20 years. The number of papers devoted to basic microplasma science increased by an order of magnitude between 1995 and 2015, a count that excludes publications dealing exclusively with technological applications of microplasmas, where the microplasma is used solely as a tool. In reference [1], the authors limited the topical coverage largely to the status of microplasma science and our understanding of the physics principles that enable microplasma operation and further stated that the rapid proliferation of microplasma applications made it impossible to cover both basic microplasma science and their application in a single review article.

  5. Atmospheric Pressure Plasma Processing for Polymer Adhesion: A Review

    DEFF Research Database (Denmark)

    Kusano, Yukihiro

    2014-01-01

    Atmospheric pressure plasma processing has attracted significant interests over decades due to its usefulness and a variety of applications. Adhesion improvement of polymer surfaces is among the most important applications of atmospheric pressure plasma treatment. Reflecting recent significant de...

  6. Harmonic Generation by Microwave-frequency Microplasma

    Science.gov (United States)

    Parsons, Stephen; Hoskinson, Alan; Hopwood, Jeffrey

    2013-09-01

    A microplasma may operate as a nonlinear circuit element and generate power at the harmonics of the drive frequency. As an example, microplasma is sustained using 1 W of power at 1.3 GHz in a small discharge gap formed in a split-ring resonator. A probe extends into the microplasma and extracts the 3rd harmonic power through a tuned resonator at 3.9 GHz. The experimental data show that this non-optimized system produces a +38 dB increase in 3rd harmonic power in the presence of a microplasma. Two origins of nonlinearity are described: the harmonic conduction current due to electron collection by microelectrodes, and the harmonic displacement current due to the voltage-dependent sheath capacitance. PIC-MC simulations suggest that the microplasma nonlinearity may also be exploited at frequencies of 100 GHz. Support was provided by the DARPA Microscale Plasma Devices program under award FA9550-12-1-0006.

  7. Deposition of organosilicone thin film from hexamethyldisiloxane (HMDSO) with 50 kHz/33 MHz dual-frequency atmospheric-pressure plasma jet

    Science.gov (United States)

    Li, Jiaojiao; Yuan, Qianghua; Chang, Xiaowei; Wang, Yong; Yin, Guiqin; Dong, Chenzhong

    2017-04-01

    The deposition of organosilicone thin films from hexamethyldisiloxane(HMDSO) by using a dual-frequency (50 kHz/33 MHz) atmospheric-pressure micro-plasma jet with an admixture of a small volume of HMDSO and Ar was investigated. The topography was measured by using scanning electron microscopy. The chemical bond and composition of these films were analyzed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy. The results indicated that the as-deposited film was constituted by silicon, carbon, and oxygen elements, and FTIR suggested the films are organosilicon with the organic component (-CH x ) and hydroxyl functional group(-OH) connected to the Si-O-Si backbone. Thin-film hardness was recorded by an MH-5-VM Digital Micro-Hardness Tester. Radio frequency power had a strong impact on film hardness and the hardness increased with increasing power.

  8. PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES: Diagnosis of Methane Plasma Generated in an Atmospheric Pressure DBD Micro-Jet by Optical Emission Spectroscopy

    Science.gov (United States)

    Zhang, Jun-Feng; Bian, Xin-Chao; Chen, Qiang; Liu, Fu-Ping; Liu, Zhong-Wei

    2009-03-01

    Diagnosis of methane plasma, generated in an atmospheric pressure dielectric barrier discharge (DBD) microplasma jet with a quartz tube as dielectric material by a 25 kHz sinusoidal ac power source, is conducted by optical emission spectroscopy (OES). The reactive radicals in methane plasma such as CH, C2, and Hα are detected insitu by OES. The possible dissociation mechanism of methane in diluted Ar plasma is deduced from spectra. In addition, the density of CH radical, which is considered as one of the precursors in diamond-like (DLC) film formation, affected by the parameters of input voltage and the feed gas flow rate, is emphasized. With the Boltzmann plots, four Ar atomic spectral lines (located at 675.28nm, 687.13nm, 738.40nm and 794.82nm, respectively) are chosen to calculate the electron temperature, and the dependence of electron temperature on discharge parameters is also investigated.

  9. Response of cyanobacteria to low atmosphere pressure

    Science.gov (United States)

    Qin, Lifeng; Ai, Weidang; Guo, Shuangsheng; Tang, Yongkang; Yu, Qingni; Shen, Yunze; Ren, Jin

    Maintaining a low pressure environment would reduce the technological complexity and constructed cost of future lunar base. To estimate the effect of hypobaric of controlled ecological life support system in lunar base on terrestrial life, cyanobacteria was used as the model to exam the response of growth, morphology, physiology to it. The decrease of atmosphere pressure from 100 KPa to 50 KPa reducing the growth rates of Microcystis aeruginosa, Merismopedia.sp, Anabaena sp. PCC 7120, Anabaena Hos-aquae, the chlorophyll a content in Microcystis aeruginosa, Merismopedia.sp, Anabaena Hos-aquae, the carotenoid content in Microcystis aeruginosa, Merismopedia.sp and Anabaena sp. PCC 7120, the phycocyanin content in Microcystis aeruginosa. This study explored the biological characteristics of the cyanobacteria under low pressure condition, which aimed at understanding the response of the earth's life to environment for the future moon base, the results enrich the research contents of the lunar biology and may be referred for the research of other terrestrial life, such as human, plant, microbe and animal living in life support system of lunar base.

  10. Atmospheric pressure variation and the climate of Mars

    Science.gov (United States)

    Gierasch, P. J.; Toon, O. B.

    1973-01-01

    If Mars has permanent CO2 polar caps, atmospheric heat transport may cause the atmospheric pressure to be extremely sensitive to variations of solar heating at the poles. This could happen because atmospheric heating depends on density, which depends strongly on the polar temperature through the vapor pressure relation. A simple climatological model is used to study the question.

  11. Atmospheric pressure variations and abdominal aortic aneurysm rupture.

    LENUS (Irish Health Repository)

    Killeen, S D

    2012-02-03

    BACKGROUND: Ruptured abdominal aortic aneurysm (RAAA) presents with increased frequency in the winter and spring months. Seasonal changes in atmospheric pressure mirrors this pattern. AIM: To establish if there was a seasonal variation in the occurrence of RAAA and to determine if there was any association with atmospheric pressure changes. METHODS: A retrospective cohort-based study was performed. Daily atmospheric pressure readings for the region were obtained. RESULTS: There was a statistically significant monthly variation in RAAA presentation with 107 cases (52.5%) occurring from November to March. The monthly number of RAAA and the mean atmospheric pressure in the previous month were inversely related (r = -0.752, r (2) = 0.566, P = 0.03), and there was significantly greater daily atmospheric pressure variability on days when patients with RAAA were admitted. CONCLUSION: These findings suggest a relationship between atmospheric pressure and RAAA.

  12. Atmospheric pressure plasma for surface modification

    CERN Document Server

    Wolf, Rory A

    2012-01-01

    This Book's focus and intent is to impart an understanding of the practical application of atmospheric plasma for the advancement of a wide range of current and emerging technologies. The primary key feature of this book is the introduction of over thirteen years of practical experimental evidence of successful surface modifications by atmospheric plasma methods. It offers a handbook-based approach for leveraging and optimizing atmospheric plasma technologies which are currently in commercial use. It also offers a complete treatment of both basic plasma physics and industrial plasma process

  13. Microplasma light tiles: thin sheet lamps for general illumination

    Science.gov (United States)

    Eden, J. G.; Park, S.-J.; Herring, C. M.; Bulson, J. M.

    2011-06-01

    Flat, thin and lightweight lamps providing spatially uniform and dimmable illumination from active areas as large as 400 cm2 are being developed for general illumination and specialty applications. Comprising an array of low-temperature, nonequilibrium microplasmas driven by a dielectric barrier structure and operating at pressures of typically 400-700 Torr, these lamps have a packaged thickness luminance values beyond 26 000 cd m-2 with a luminous efficacy approaching 30 lm W-1. Third generation lamps, presently in limited production, offer a correlated colour temperature in the 3000-4100 K interval and a colour rendering index of 80. Current lamps employ Xe2 (λ ~ 172 nm) as the primary emitter photoexciting a mixture of phosphors, and the pressure dependence of the wavelength-integrated fluorescence from the electronically excited dimer has been investigated with a vacuum ultraviolet spectrometer. In contrast to other promising lighting technologies, the decline in luminous efficacy of microplasma lamps with increasing power delivered to the lamp is small. For a 6 × 6 inch2 (~225 cm2) lamp, efficacy falls luminance) is raised from 2000 cd m-2 to > 10 000 cd m-2.

  14. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC's Non-Thermal Sanitation by Atmospheric Pressure Plasma technology sanitizes fresh fruits and vegetables without the use of consumable chemicals and without...

  15. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop a non-thermal technology based on atmospheric-pressure (AP) cold plasma to sanitize foods, food packaging materials, and other hardware...

  16. Surface Pressure Measurements of Atmospheric Tides Using Smartphones

    Science.gov (United States)

    Price, Colin; Maor, Ron

    2017-04-01

    Similar to the oceans, the atmosphere also has tides that are measured in variations of atmospheric pressure. However, unlike the gravitational tides in the oceans, the atmospheric tides are caused primarily in the troposphere and stratosphere when the atmosphere is periodically heated by the sun, due to tropospheric absorption by water vapor and stratospheric absorption by ozone. Due to the forcing being always on the day side of the globe, the tides migrate around the globe following the sun (migrating tides) with a dominant periodicity of 12 hours (and less so at 24 hours). In recent years smartphones have been equipped with sensitive, cheap and reliable pressure sensors that can easily detect these atmospheric tides. By 2020 it is expected that there will be more than 6 billion smartphones globally, each measuring continuously atmospheric pressure at 1Hz temporal resolution. In this presentation we will present some control experiments we have performed with smartphones to monitor atmospheric tides, while also using random pressure data from more than 50,000 daily users via the WeatherSignal application. We conclude that smartphones are a useful tool for studying atmospheric tides on local and global scales.

  17. Biomedical applications and diagnostics of atmospheric pressure plasma

    Science.gov (United States)

    Petrović, Z. Lj; Puač, N.; Lazović, S.; Maletić, D.; Spasić, K.; Malović, G.

    2012-03-01

    Numerous applications of non-equilibrium (cold, low temperature) plasmas require those plasmas to operate at atmospheric pressure. Achieving non-equilibrium at atmospheric pressure is difficult since the ionization growth is very fast at such a high pressure. High degree of ionization on the other hand enables transfer of energy between electrons and ions and further heating of the background neutral gas through collisions between ions and neutrals. Thus, all schemes to produce non-equilibrium plasmas revolve around some form of control of ionization growth. Diagnostics of atmospheric pressure plasmas is difficult and some of the techniques cannot be employed at all. The difficulties stem mostly from the small size. Optical emission spectroscopy and laser absorption spectroscopy require very high resolution in order to resolve the anatomy of the discharges. Mass analysis is not normally applicable for atmospheric pressure plasmas, but recently systems with triple differential pumping have been developed that allow analysis of plasma chemistry at atmospheric pressures which is essential for numerous applications. Application of such systems is, however, not free from problems. Applications in biomedicine require minimum heating of the ambient air. The gas temperature should not exceed 40 °C to avoid thermal damage to the living tissues. Thus, plasmas should operate at very low powers and power control is essential. We developed unique derivative probes that allow control of power well below 1 W and studied four different sources, including dielectric barrier discharges, plasma needle, atmospheric pressure jet and micro atmospheric pressure jet. The jet operates in plasma bullet regime if proper conditions are met. Finally, we cover results on treatment of bacteria and human cells as well as treatment of plants by plasmas. Localized delivery of active species by plasmas may lead to a number of medical procedures that may also involve removal of bacteria, fungi and

  18. Microplasmas ignited and sustained by microwaves

    Science.gov (United States)

    Hopwood, Jeffrey; Hoskinson, Alan R.; Gregório, José

    2014-12-01

    The challenges and benefits of microwave-induced microdischarges are reviewed. Transmission lines, resonators and surface wave launchers may be used for coupling microwave power to very small plasmas. Fortunately, microplasmas are typically much smaller than the wavelength of microwaves, and the electromagnetic problem may be treated electrostatically within the plasma. It is possible to trap electrons within small discharge gaps if the amplitude of electron oscillation is smaller than the plasma size. Typically occurring above 0.3 GHz, this condition results in lower breakdown fields than are required by direct current or radio frequency systems. Trapping of electrons also decreases the electrode potential to only tens of volts and makes the plasma density invariant in time. The steady-state microplasma produces electron densities of up to 1015 cm-3 in argon but the electrons are not in equilibrium with the low gas temperatures (500-1000 K). Microwave discharges are compared with other forms of microplasma and guidelines for device selection are recommended. Scale-up of microplasmas using array concepts are presented followed by some exciting new applications.

  19. Vapor phase growth of functional pentacene films at atmospheric pressure

    NARCIS (Netherlands)

    Rolin, C.; Vasseur, K.; Niesen, B.; Willegems, M.; Müller, R.; Steudel, S.; Genoe, J.; Heremans, P.

    2012-01-01

    Compared to traditional vacuum evaporation techniques for small organic molecules, organic vapor phase deposition (OVPD) possesses a extra processing parameter: the pressure of process gas Pch. Here, the influence of large Pch variations (from 0.1 mbar to atmospheric pressure) on pentacene thin film

  20. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    2012-01-01

    Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasm...

  1. Atmospheric and pressurized fluidized bed technology

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, E.J.B. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre

    2003-07-01

    Fluidization states, bubbling and circulating fluidized beds, and the basics of pressurized fluidized bed combustion are outlined. PFBC demonstration plants, cogeneration, operational units and possible new plants, growth of PFBC capacity, sulphur capture, sulphation, phase composition of ashes, and actual performance in reduction of sulphur dioxide and nitrogen oxides are described. Problems occurring during operation show that turbines need to be protected and that hot gas filters degrade and are unreliable. It is concluded that the future of PFBC depends on Asian development and that the technology may be stimulated by stricter pollution controls. 5 figs., 4 tabs.

  2. Foundations of atmospheric pressure non-equilibrium plasmas

    Science.gov (United States)

    Bruggeman, Peter J.; Iza, Felipe; Brandenburg, Ronny

    2017-12-01

    Non-equilibrium plasmas have been intensively studied over the past century in the context of material processing, environmental remediation, ozone generation, excimer lamps and plasma display panels. Research on atmospheric pressure non-equilibrium plasmas intensified over the last two decades leading to a large variety of plasma sources that have been developed for an extended application range including chemical conversion, medicine, chemical analysis and disinfection. The fundamental understanding of these discharges is emerging but there remain a lot of unexplained phenomena in these intrinsically complex plasmas. The properties of non-equilibrium plasmas at atmospheric pressure span over a huge range of electron densities as well as heavy particle and electron temperatures. This paper provides an overview of the key underlying processes that are important for the generation and stabilization of atmospheric pressure non-equilibrium plasmas. The unique physical and chemical properties of theses discharges are also summarized.

  3. Characterization of a microwave-excited atmospheric-pressure argon plasma jet using two-parallel-wires transmission line resonator

    Science.gov (United States)

    Choi, J.; Eom, I. S.; Kim, S. J.; Kwon, Y. W.; Joh, H. M.; Jeong, B. S.; Chung, T. H.

    2017-09-01

    This paper presents a method to produce a microwave-excited atmospheric-pressure plasma jet (ME-APPJ) with argon. The plasma was generated by a microwave-driven micro-plasma source that uses a two-parallel-wire transmission line resonator (TPWR) operating at around 900 MHz. The TPWR has a simple structure and is easier to fabricate than coaxial transmission line resonator (CTLR) devices. In particular, the TPWR can sustain more stable ME-APPJ than the CTLR can because the gap between the electrodes is narrower than that in the CTLR. In experiments performed with an Ar flow rate from 0.5 to 8.0 L.min-1 and an input power from 1 to 6 W, the rotational temperature was determined by comparing the measured and simulated spectra of rotational lines of the OH band and the electron excitation temperature determined by the Boltzmann plot method. The rotational temperature obtained from OH(A-X) spectra was 700 K to 800 K, whereas the apparent gas temperature of the plasma jet remains lower than ˜325 K, which is compatible with biomedical applications. The electron number density was determined using the method based on the Stark broadening of the hydrogen Hβ line, and the measured electron density ranged from 6.5 × 1014 to 7.6 × 1014 cm-3. TPWR ME-APPJ can be operated at low flows of the working gas and at low power and is very stable and effective for interactions of the plasma with cells.

  4. Discharge Mechanism in Voids at Sub-Atmospheric Pressures

    OpenAIRE

    B.Ramachandra; Nema, RS

    1998-01-01

    The physical processes occurring during partial discharges (PD) in voids in solid dielectrics are complicated due to the lack of knowledge of void shape, location and gas pressure. Fast oscilloscopic techniques are needed to measure the build up and decay of current as a function of time for single discharges. The purpose of the present work is to investigate the mechanism of the discharge in artificial voids in thin polypropylene (PP) films at different sub-atmospheric pressures. Efforts hav...

  5. Influence of geomagnetic activity and atmospheric pressure in hypertensive adults

    Science.gov (United States)

    Azcárate, T.; Mendoza, B.

    2017-09-01

    We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

  6. (Congressional) Center for Microplasma Science and Technology

    Science.gov (United States)

    2012-03-29

    the plasma to move freely about the  structure . In addition, they can be assembled in various configurations, e.g.  planar, multi‐layer, and...an antifungal therapy, Applied Physics Letters, 98 (2011) 021501  K. H. Becker, H. Kersten, J. Hopwood, and J. L. Lopez. Microplasmas: scientific

  7. On the permanent hip-stabilizing effect of atmospheric pressure.

    Science.gov (United States)

    Prietzel, Torsten; Hammer, Niels; Schleifenbaum, Stefan; Kaßebaum, Eric; Farag, Mohamed; von Salis-Soglio, Georg

    2014-08-22

    Hip joint dislocations related to total hip arthroplasty (THA) are a common complication especially in the early postoperative course. The surgical approach, the alignment of the prosthetic components, the range of motion and the muscle tone are known factors influencing the risk of dislocation. A further factor that is discussed until today is atmospheric pressure which is not taken into account in the present THA concepts. The aim of this study was to investigate the impact of atmospheric pressure on hip joint stability. Five joint models (Ø 28-44 mm), consisting of THA components were hermetically sealed with a rubber capsule, filled with a defined amount of fluid and exposed to varying ambient pressure. Displacement and pressure sensors were used to record the extent of dislocation related to intraarticular and ambient pressure. In 200 experiments spontaneous dislocations of the different sized joint models were reliably observed once the ambient pressure was lower than 6.0 kPa. Increasing the ambient pressure above 6.0 kPa immediately and persistently reduced the joint models until the ambient pressure was lowered again. Displacement always exceeded half the diameter of the joint model and was independent of gravity effects. This experimental study gives strong evidence that the hip joint is permanently stabilized by atmospheric pressure, confirming the theories of Weber and Weber (1836). On basis of these findings the use of larger prosthetic heads, capsular repair and the deployment of an intracapsular Redon drain are proposed to substantially decrease the risk of dislocation after THA. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Designing Extraterrestrial Plant Growth Habitats with Low Pressure Atmospheres

    Science.gov (United States)

    Corey, Kenneth A.

    2002-01-01

    In-situ resource utilization, provision of human life support requirements by bioregenerative methods, and engineering constraints for construction and deployment of plant growth structures on the surface of Mars all suggest the need for plant growth studies at hypobaric pressures. Past work demonstrated that plants will likely tolerate and grow at pressures at or below 10 kPa. Based upon this premise, concepts are developed for the design of reduced pressure atmospheres in lightweight, inflatable structures for plant growth systems on Mars with the goals of maximizing design simplicity and the use of local resources. A modular pod design is proposed as it could be integrated with large-scale production systems. Atmospheric modification of pod clusters would be based upon a pulse and scrub system using mass flow methods for atmospheric transport. A specific modification and control scenario is developed for a lettuce pod to illustrate the dynamics of carbon dioxide and oxygen exchange within a pod. Considerations of minimal atmospheric crop requirements will aid in the development of engineering designs and strategies for extraterrestrial plant growth structures that employ rarefied atmospheres.

  9. Atmospheric pressure photoionization using tunable VUV synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Giuliani, A., E-mail: alexandre.giuliani@synchrotron-soleil.fr [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); INRA, U1008 CEPIA, Rue de la Geraudiere, F-44316 Nantes (France); Giorgetta, J.-L.; Ricaud, J.-P. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); Jamme, F. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); INRA, U1008 CEPIA, Rue de la Geraudiere, F-44316 Nantes (France); Rouam, V.; Wien, F. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); Laprevote, O. [Laboratoire de Spectrometrie de Masse, ICSN-CNRS, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette (France); Laboratoire de Chimie-Toxicologie Analytique et cellulaire, IFR 71, Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, 4 Avenue de l' Observatoire, 75006 Paris (France); Refregiers, M. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Coupling of an atmospheric pressure photoionization source with a vacuum ultra-violet (VUV) beamline. Black-Right-Pointing-Pointer The set up allows photoionization up to 20 eV. Black-Right-Pointing-Pointer Compared to classical atmospheric pressure photoionization (APPI), our set up offers spectral purity and tunability. Black-Right-Pointing-Pointer Allows photoionization mass spectrometry on fragile and hard to vaporize molecules. - Abstract: We report here the first coupling of an atmospheric pressure photoionization (APPI) source with a synchrotron radiation beamline in the vacuum ultra-violet (VUV). A commercial APPI source of a QStar Pulsar i from AB Sciex was modified to receive photons from the DISCO beamline at the SOLEIL synchrotron radiation facility. Photons are delivered at atmospheric pressure in the 4-20 eV range. The advantages of this new set up, termed SR-APPI, over classical APPI are spectral purity and continuous tunability. The technique may also be used to perform tunable photoionization mass spectrometry on fragile compounds difficult to vaporize by classical methods.

  10. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    Science.gov (United States)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  11. Einstein's Tea Leaves and Pressure Systems in the Atmosphere

    Science.gov (United States)

    Tandon, Amit; Marshall, John

    2010-01-01

    Tea leaves gather in the center of the cup when the tea is stirred. In 1926 Einstein explained the phenomenon in terms of a secondary, rim-to-center circulation caused by the fluid rubbing against the bottom of the cup. This explanation can be connected to air movement in atmospheric pressure systems to explore, for example, why low-pressure…

  12. Negative ion-atmospheric pressure photoionization-mass spectrometry

    NARCIS (Netherlands)

    Kauppila, T.J.; Kotiaho, T.; Kostiainen, R; Bruins, A.P.

    The ionization mechanism in the novel atmospheric pressure photoionization mass spectrometry (APPI-MS) in negative ion mode was studied thoroughly by the analysis of seven compounds in 17 solvent systems. The compounds possessed either gas-phase acidity or positive electron affinity, whereas the

  13. Electrolytic synthesis of ammonia in molten salts under atmospheric pressure.

    Science.gov (United States)

    Murakami, Tsuyoshi; Nishikiori, Tokujiro; Nohira, Toshiyuki; Ito, Yasuhiko

    2003-01-15

    Ammonia was successfully synthesized by using a new electrochemical reaction with high current efficiency at atmospheric pressure and at lower temperatures than the Haber-Bosch process. In this method, nitride ion (N3-), which is produced by the reduction from nitrogen gas at the cathode, is anodically oxidized and reacts with hydrogen to produce ammonia at the anode.

  14. Atmospheric pressure CVD of SNO2 and ZNO:AL

    NARCIS (Netherlands)

    Deelen, J. van; Kniknie, B.J.; Steijvers, H.L.A.H.; Mannie, G.; Thune, P.; Illiberi, A.

    2012-01-01

    Atmospheric pressure CVD (APCVD) is a highly cost effective method of depositing transparent conductive oxides (TCOs). In this work, insights in alcohol addition in the widely applied SnO2 process are discussed, including high resolution TEM images. Furthermore, the APCVD process of ZnO:Al was

  15. Generation of uniform atmospheric pressure argon glow plasma by ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 80; Issue 3. Generation of uniform atmospheric pressure argon glow plasma by dielectric barrier discharge. Raju Bhai Tyata Deepak Prasad Subedi Rajendra Shrestha Chiow San Wong. Research Articles Volume 80 Issue 3 March 2013 pp 507-517 ...

  16. Atmospheric-pressure guided streamers for liposomal membrane disruption

    Energy Technology Data Exchange (ETDEWEB)

    Svarnas, P.; Aleiferis, Sp. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26504 (Greece); Matrali, S. H. [Pharmaceutical Technology Laboratory, Department of Pharmacy, University of Patras, Rion 26504 (Greece); Gazeli, K. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26504 (Greece); IPREM-LCABIE, Plasmas et Applications, UPPA, 64000 Pau (France); Clement, F. [IPREM-LCABIE, Plasmas et Applications, UPPA, 64000 Pau (France); Antimisiaris, S. G. [Pharmaceutical Technology Laboratory, Department of Pharmacy, University of Patras, Rion 26504 (Greece); Institute of Chemical Engineering Sciences (ICES)-FORTH, Rion 26504 (Greece)

    2012-12-24

    The potential to use liposomes (LIPs) as a cellular model in order to study interactions of cold atmospheric-pressure plasma with cells is herein investigated. Cold atmospheric-pressure plasma is formed by a dielectric-barrier discharge reactor. Large multilamellar vesicle liposomes, consisted of phosphatidylcholine and cholesterol, are prepared by the thin film hydration technique, to encapsulate a small hydrophilic dye, i.e., calcein. The plasma-induced release of calcein from liposomes is then used as a measure of liposome membrane integrity and, consequently, interaction between the cold atmospheric plasma and lipid bilayers. Physical mechanisms leading to membrane disruption are suggested, based on the plasma characterization including gas temperature calculation.

  17. Quality characteristics of the radish grown under reduced atmospheric pressure

    Science.gov (United States)

    Levine, Lanfang H.; Bisbee, Patricia A.; Richards, Jeffrey T.; Birmele, Michele N.; Prior, Ronald L.; Perchonok, Michele; Dixon, Mike; Yorio, Neil C.; Stutte, Gary W.; Wheeler, Raymond M.

    This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12 kPa, respectively. Plants were harvested at 21 days after planting, with aerial shoots and swollen hypocotyls (edible portion of the radish referred to as the “root” hereafter) separated immediately upon removal from the chambers. Samples were subsequently evaluated for their sensory characteristics (color, taste, overall appearance, and texture), taste-determining factors (glucosinolate and soluble carbohydrate content and myrosinase activity), proximate nutrients (protein, dietary fiber, and carbohydrate) and potential health benefit attributes (antioxidant capacity). In roots of control plants, concentrations of glucosinolate, total soluble sugar, and nitrate, as well as myrosinase activity and total antioxidant capacity (measured as ORACFL), were 2.9, 20, 5.1, 9.4, and 1.9 times greater than the amount in leaves, respectively. There was no significant difference in total antioxidant capacity, sensory characteristics, carbohydrate composition, or proximate nutrient content among the three pressure treatments. However, glucosinolate content in the root and nitrate concentration in the leaf declined as the atmospheric pressure decreased, suggesting perturbation to some nitrogen-related metabolism.

  18. ATMOSPHERE PRESSURE EFFECT ON THE FIBER OPTIC GYROSCOPE OUTPUT SYGNAL

    Directory of Open Access Journals (Sweden)

    Ilya A. Sharkov

    2017-05-01

    Full Text Available The paper describes research results of the atmospheric pressure effect on the output signal of a fiber optic gyroscope (FOG. In the course of experiments, FOG was placed into a hermetic chamber. The atmosphere pressure was varying in the range from 0.8 to 1.5 atm. All the data, including the FOG output signal, temperature, and data from the pressure sensor installed inside the FOG, were synchronously registered with the computer software. The separation of scale factor change from zero offset in the experiment was carried out by setting the sensitive FOG axis at 0°, 90° and 270° relative to the East (the FOG was set perpendicular to the horizon. After the data processing it was concluded that the FOG signal error associated with the pressure affects mainly on the additive component. The pressure effect on the multiplicative component appeared to be negligible at rotational velocities used in the experiment (0 - 130 /h. At the same time, the FOG signal has a high linear correlation coefficient with the derivative of pressure over time (in some cases, more than 0.9. The experiment was repeated several times and the high degree of the drift repeatability was shown. That makes it possible to implement the compensation algorithm. Application of the simplest algorithmic compensation based on the polynomial of the first degree (ax + b enabled to reduce the root-mean-square (RMS and drift of the signal by 2-9 times.

  19. A Micromachined Pressure Sensor with Integrated Resonator Operating at Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Sen Ren

    2013-12-01

    Full Text Available A novel resonant pressure sensor with an improved micromechanical double-ended tuning fork resonator packaged in dry air at atmospheric pressure is presented. The resonator is electrostatically driven and capacitively detected, and the sensor is designed to realize a low cost resonant pressure sensor with medium accuracy. Various damping mechanisms in a resonator that is vibrating at atmospheric pressure are analyzed in detail, and a formula is developed to predict the overall quality factor. A trade-off has been reached between the quality factor, stress sensitivity and drive capability of the resonator. Furthermore, differential sense elements and the method of electromechanical amplitude modulation are used for capacitive detection to obtain a large signal-to-noise ratio. The prototype sensor chip is successfully fabricated using a micromachining process based on a commercially available silicon-on-insulator wafer and is hermetically encapsulated in a custom 16-pin Kovar package. Preliminary measurements show that the fundamental frequency of the resonant pressure sensor is approximately 34.55 kHz with a pressure sensitivity of 20.77 Hz/kPa. Over the full scale pressure range of 100–400 kPa and the whole temperature range of −20–60 °C, high quality factors from 1,146 to 1,772 are obtained. The characterization of the prototype sensor reveals the feasibility of a resonant pressure sensor packaged at atmospheric pressure.

  20. Benchmark continuum and kinetic simulations of argon microplasmas in the direct current and microwave regimes

    Science.gov (United States)

    Verma, Abhishek Kumar; Alamatsaz, Arghavan; Venkattraman, Ayyaswamy

    2017-10-01

    This study presents benchmark comparisons between continuum and kinetic simulations of argon microplasmas operating in the direct current and microwave regimes. Kinetic simulations using the particle-in-cell with Monte Carlo collisions (PIC-MCC) method and continuum simulations using the full-momentum equation for both ions and electrons are performed at various operating conditions in order to study the influence of product of pressure and gap size, pd (for a given gap size), influence of gap size (for a given value of pd) and operating frequency. It is shown that using the electron energy distribution function (EEDF) predicted by zero-dimensional Boltzmann solvers (such as BOLSIG+) in continuum simulations of direct current microplasmas leads to a significant under-prediction of plasma number densities with continuum simulations based on the Maxwellian EEDF performing better particularly for higher values of pd. The discrepancy between kinetic and continuum simulations is attributed to the presence of hot electrons created as a result of secondary emission and subsequent acceleration in the sheath. On the other hand, simulations performed for argon microwave microplasmas operating at 0.5 GHz, 0.8 GHz, 2 GHz and 4 GHz demonstrated that continuum simulations performed using the rate constants from BOLSIG+  showed excellent agreement with kinetic simulations for the plasma density profiles in spite of over-predicting the voltage/power required to achieve a given plasma density.

  1. Atmospheric pressure loading effects on Global Positioning System coordinate determinations

    Energy Technology Data Exchange (ETDEWEB)

    Vandam, T.M.; Blewitt, G.; Heflin, M.B. [NOAA, Silver Spring, MD (United States)]|[Univ. of Newcastle upon Tyne, Newcastle upon Tyne (United Kingdom)]|[Jet Propulsion Laboratory, Pasadena, CA (United States)

    1994-12-01

    Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65 deg), with a signal root mean square (RMS) of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements. Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Removing the modeled pressure loading from GPS determinations of baseline length for baselines longer than 6000 km reduces the variance on 73 of the 117 baselines investigated. The slight increase in variance for some of the sites and baselines is consistent with expected statistical fluctuations. The results from most stations are consistent with approximately 65% of the modeled pressure load being found in the GPS vertical position measurements. Removing an annual signal from both the measured heights and the modeled load time series leaves this value unchanged.

  2. Atmospheric sugar alcohols: evaporation rates and saturation vapor pressures

    DEFF Research Database (Denmark)

    Bilde, Merete; Zardini, Alessandro Alessio; Hong, Juan

    volatile organic molecules. Saturation vapor pressure and the associated temperature dependence (dH) are key parameters for improving predictive atmospheric models. In this work we combine experiments and thermodynamic modeling to investigate these parameters for a series of polyols, so-called sugar...... are allowed to evaporate in a laminar flow reactor, and changes in particle size as function of evaporation time are determined using a scanning mobility particle sizer system. In this work saturation vapor pressures of sugar alcohols at several temperatures have been inferred from such measurements using...

  3. Removal of paper microbial contamination by atmospheric pressure DBD discharge

    Science.gov (United States)

    Vrajova, J.; Chalupova, L.; Novotny, O.; Cech, J.; Krcma, F.; Stahel, P.

    2009-08-01

    In this paper the removal of the microbial contamination from paper material using the plasma treatment at atmospheric pressure is investigated. The Aspergillus niger has been chosen as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. Dielectric barrier discharge (DBD) operated at atmospheric pressure was used for the paper sterilization. The working gas (nitrogen, argon and helium), plasma exposition time and the plasma power density were varied in order to see the effect of the plasma treatment on the fungi removal. After the treatment, the microbial abatement was evaluated by the standard plate count method. This proved a positive effect of the DBD plasma treatment on fungi removal. Morphological and colorimetric changes of paper substrate after plasma treatment were also investigated.

  4. Cellular membrane collapse by atmospheric-pressure plasma jet

    Science.gov (United States)

    Kim, Kangil; Jun Ahn, Hak; Lee, Jae-Hyeok; Kim, Jae-Ho; Sik Yang, Sang; Lee, Jong-Soo

    2014-01-01

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  5. Ferrous alloys cast under high pressure gas atmosphere

    Directory of Open Access Journals (Sweden)

    Pirowski Z.

    2007-01-01

    Full Text Available The main objective of this paper is describing the essence of the process of introducing nitrogen to the melt of ferrous alloys by application of overpressure above the metal bath. The problem was discussed in terms of both theory (the thermodynamic aspects of the process and practice (the technical and technological aspects, safety of the furnace stand operation, and technique of conducting the melt. The novel technique of melting under high pressure of the gas atmosphere (up to 5 MPa has not been used so far in the domestic industry, mainly because of the lack of proper equipment satisfyng the requirements of safe operation. Owing to cooperation undertaken with a partner from Bulgaria, a more detailed investigation of this technology has become possible and melting of selected ferrous alloys was conducted under the gas atmosphere at a pressure of about 3,5 MPa.

  6. Reduced atmospheric pressure in Radish: Alteration of NCER and transpiration at decreased oxygen partial pressures

    Science.gov (United States)

    Wehkamp, Cara Ann; Stasiak, Michael; Wheeler, Raymond; Dixon, Mike

    Fundamental to the future of space exploration is the development of advanced life support systems capable of maintaining crews for significant periods without re-supply from Earth. Significant research is focused on the development of bioregenerative life support systems to be used in conjunction with the current physico-chemical methods. These bioregenerative life support systems harness natural ecosystem processes and employ plant photosynthesis and transpiration to produce food, oxygen and regenerate water while consuming carbon dioxide. The forthcoming exploration of the Moon and Mars has prompted interest into the effects of hypobaria on plant development. Reduced atmospheric pressures will lessen the pressure gradient between the structure and the local environment thereby decreasing gas leakage and possibly the structural mass of the plant growth facility. In order to establish the optimal specifications for reduced pressure plant growth structures it is essential to determine the atmospheric pressure limits required for conventional plant development and growth. Due to its physiological importance, oxygen will compose a significant portion of these minimal environments. The objective of this study was to test the hypothesis that reduced atmospheric pressure and decreased oxygen partial pressures had no effect on radish productivity. Radishes (Raphanus sativa L. cv. Cherry Bomb II) were grown from seed in the University of Guelph's Hypobaric Plant Growth Chambers for a period of 21 days. Treatments included total pressures of 10, 33, 66 and 96 kPa and oxygen partial pressures of 2, 7, 14 and 20 kPa. Experiments demonstrated that reduced partial pressures of oxygen had a greater effect on radish growth than hypobaria. Results showed a reduction in net carbon exchange rate and transpiration with decreasing oxygen partial pressures leading to diminished productivity. Keywords: hypobaric, radish, oxygen partial pressure, variable pressure chamber

  7. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Science.gov (United States)

    Vasile Nastuta, Andrei; Topala, Ionut; Grigoras, Constantin; Pohoata, Valentin; Popa, Gheorghe

    2011-03-01

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  8. Infrared laser ablation atmospheric pressure photoionization mass spectrometry.

    Science.gov (United States)

    Vaikkinen, Anu; Shrestha, Bindesh; Kauppila, Tiina J; Vertes, Akos; Kostiainen, Risto

    2012-02-07

    In this paper we introduce laser ablation atmospheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass spectrometry. In LAAPPI the analytes are ablated from water-rich solid samples or from aqueous solutions with an infrared (IR) laser running at 2.94 μm wavelength. Approximately 12 mm above the sample surface, the ablation plume is intercepted with an orthogonal hot solvent (e.g., toluene or anisole) jet, which is generated by a heated nebulizer microchip and directed toward the mass spectrometer inlet. The ablated analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 eV vacuum ultraviolet krypton discharge lamp. The effect of operational parameters and spray solvent on the performance of LAAPPI is studied. LAAPPI offers ~300 μm lateral resolution comparable to, e.g., matrix-assisted laser desorption ionization. In addition to polar compounds, LAAPPI efficiently ionizes neutral and nonpolar compounds. The bioanalytical application of the method is demonstrated by the direct LAAPPI analysis of rat brain tissue sections and sour orange (Citrus aurantium) leaves. © 2012 American Chemical Society

  9. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Nastuta, Andrei Vasile; Topala, Ionut; Pohoata, Valentin; Popa, Gheorghe [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol No. 11, 700506, Iasi (Romania); Grigoras, Constantin, E-mail: andrei.nastuta@uaic.ro [Physiopathology Department, Grigore T. Popa University of Medicine and Pharmacy, 700115, Iasi (Romania)

    2011-03-16

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  10. Microplasma device architectures with various diamond nanostructures

    Science.gov (United States)

    Kunuku, Srinivasu; Jothiramalingam Sankaran, Kamatchi; Leou, Keh-Chyang; Lin, I.-Nan

    2017-02-01

    Diamond nanostructures (DNSs) were fabricated from three different morphological diamonds, microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films, using a reactive ion etching method. The plasma illumination (PI) behavior of microplasma devices using the DNSs and the diamond films as cathode were investigated. The Paschen curve approach revealed that the secondary electron emission coefficient (γ value) of diamond materials is similar irrespective of the microstructure (MCD, NCD, and UNCD) and geometry of the materials (DNSs and diamond films). The diamond materials show markedly larger γ-coefficient than conventional metallic cathode materials such as Mo that resulted in markedly better PI behavior for the corresponding microplasma devices. Moreover, the PI behavior, i.e. the voltage dependence of plasma current density (J pl-V), plasma density (n e-V), and the robustness of the devices, varied markedly with the microstructure and geometry of the cathode materials that was closely correlated to the electron field emission (EFE) properties of the cathode materials. The UNCD nanopillars, possessing good EFE properties, resulted in superior PI behavior, whereas the MCD diamond films with insufficient EFE properties led to inferior PI behavior. Consequently, enhancement of plasma characteristics is the collective effects of EFE behavior and secondary electron emission characteristics of diamond-based cathode materials.

  11. Microwave generation of stable atmospheric-pressure fireballs in air

    Science.gov (United States)

    Stephan, Karl D.

    2006-11-01

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed.

  12. Standard test method for using atmospheric pressure rotating cage

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers a generally accepted procedure to conduct the rotating cage (RC) experiment under atmospheric pressure. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  13. Atmospheric pressure plasma treatment of glassy carbon for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, Henrik Junge; Stenum, Bjarne

    2007-01-01

    density increased with the plasma treatments. Adhesion test of the treated glassy carbon covered with cured epoxy showed cohesive failure, indicating strong bonding after the treatments. This is in contrast to the adhesion tests of untreated samples where the epoxy readily peeled off the glassy carbon.......Glassy carbon plates were treated with an atmospheric pressure dielectric barrier discharge (DBD). He gas, gas mixtures of He and reactive gases such as O2, CO2 and NH3, Ar gas and Ar/NH3 gas mixture were used as treatment gases. The oxygen and nitrogen contents on the surface as well as defect...

  14. Driven Motion and Instability of an Atmospheric Pressure Arc

    Energy Technology Data Exchange (ETDEWEB)

    Max Karasik

    1999-12-01

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental arc furnace is constructed and operated in air with graphite cathode and steel anode at currents 100-250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes.

  15. Ultrafast laser-collision-induced fluorescence in atmospheric pressure plasma

    Science.gov (United States)

    Barnat, E. V.; Fierro, A.

    2017-04-01

    The implementation and demonstration of laser-collision-induced fluorescence (LCIF) generated in atmospheric pressure helium environments is presented in this communication. As collision times are observed to be fast (~10 ns), ultrashort pulse laser excitation (discharge conditions presented in this study (640 Torr He), the lower limit of electron density detection is ~1012 e cm-3. The spatial profiles of the 23S helium metastable and electrons are presented as functions of E/N to demonstrate the spatial resolving capabilities of the LCIF method.

  16. Generation of subnanosecond electron beams in air at atmospheric pressure

    Science.gov (United States)

    Kostyrya, I. D.; Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Rybka, D. V.

    2009-11-01

    Optimum conditions for the generation of runaway electron beams with maximum current amplitudes and densities in nanosecond pulsed discharges in air at atmospheric pressure are determined. A supershort avalanche electron beam (SAEB) with a current amplitude of ˜30 A, a current density of ˜20 A/cm2, and a pulse full width at half maximum (FWHM) of ˜100 ps has been observed behind the output foil of an air-filled diode. It is shown that the position of the SAEB current maximum relative to the voltage pulse front exhibits a time shift that varies when the small-size collector is moved over the foil surface.

  17. Microplasma source based on a dielectric barrier discharge for the determination of mercury by atomic emission spectrometry.

    Science.gov (United States)

    Zhu, Zhenli; Chan, George C-Y; Ray, Steven J; Zhang, Xinrong; Hieftje, Gary M

    2008-11-15

    A low-power, atmospheric-pressure microplasma source based on a dielectric barrier discharge (DBD) has been developed for use in atomic emission spectrometry. The small plasma (0.6 mm x 1 mm x 10 mm) is generated within a glass cell by using electrodes that do not contact the plasma. Powered by an inexpensive ozone generator, the discharge ignites spontaneously, can be easily sustained in Ar or He at gas flow rates ranging from 5 to 200 mL min(-1), and requires less than 1 W of power. The effect of operating parameters such as plasma gas identity, plasma gas flow rate, and residual water vapor on the DBD source performance has been investigated. The plasma can be operated without removal of residual water vapor, permitting it to be directly coupled with cold vapor generation sample introduction. The spectral background of the source is quite clean in the range from 200 to 260 nm with low continuum and structured components. The DBD source has been applied to the determination of Hg by continuous-flow, cold vapor generation and offers detection limits from 14 (He-DBD) to 43 pg mL(-1) (Ar-DBD) without removal of the residual moisture. The use of flow injection with the He-DBD permits measurement of Hg with a 7.2 pg limit of detection, and with repetitive injections having an RSD of <2% for a 10 ng mL(-1) standard.

  18. A comparative study of the reduction of silver and gold salts in water by a cathodic microplasma electrode

    Science.gov (United States)

    De Vos, Caroline; Baneton, Joffrey; Witzke, Megan; Dille, Jean; Godet, Stéphane; Gordon, Michael J.; Mohan Sankaran, R.; Reniers, François

    2017-03-01

    A comparative study of the reduction of aqueous silver (Ag) and gold (Au) salts to colloidal Ag and Au nanoparticles, respectively, by a gaseous, cathodic, atmospheric-pressure microplasma electrode is presented. The resulting nanoparticles (NPs) were characterized by ultraviolet-visible (UV-vis) absorption spectroscopy and transmission electron microscopy (TEM), and the aqueous solution composition before and after experiments was determined by ionic conductivity, electrochemical potential, and/or UV-vis absorption measurements. TEM showed that Ag and Au NPs were spherical and non-agglomerated when synthesized in the presence of a stabilizer, polyvinyl alcohol. The charge injected by the plasma was correlated to the maximum intensity in the absorbance spectra which in turn depends on the nanoparticle concentration. Separately, the charge injected was correlated to the metal cation concentration. Ag and Au reduction rates were found to be directly proportional to the charge injected, independent of plasma current and process time. Differences in the mechanism for Ag and Au reduction were also observed, and solution species generated by the plasma and their role in the reduction process (e.g. H2O2, electrons) is discussed.

  19. Atmospheric pressure and suicide attempts in Helsinki, Finland

    Science.gov (United States)

    Hiltunen, Laura; Ruuhela, Reija; Ostamo, Aini; Lönnqvist, Jouko; Suominen, Kirsi; Partonen, Timo

    2012-11-01

    The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods ( P weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

  20. Exploration to generate atmospheric pressure glow discharge plasma in air

    Science.gov (United States)

    Wenzheng, LIU; Chuanlong, MA; Shuai, ZHAO; Xiaozhong, CHEN; Tahan, WANG; Luxiang, ZHAO; Zhiyi, LI; Jiangqi, NIU; Liying, ZHU; Maolin, CHAI

    2018-03-01

    Atmospheric pressure glow discharge (APGD) plasma in air has high application value. In this paper, the methods of generating APGD plasma in air are discussed, and the characteristics of dielectric barrier discharge (DBD) in non-uniform electric field are studied. It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress. Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field, the development of electron avalanches in air-gap is suppressed effectively and a large space of APGD plasma in air is generated. Further, through combining electrode structures, a large area of APGD plasma in air is generated. On the other hand, by using the method of increasing the density of initial electrons, millimeter-gap glow discharge in atmospheric pressure air is formed, and a maximum gap distance between electrodes is 8 mm. By using the APGD plasma surface treatment device composed of contact electrodes, the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained. The present paper provides references for the researchers of industrial applications of plasma.

  1. Development of atmospheric pressure plasma needle jet for sterilization applications

    Science.gov (United States)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Soon, Chin Fhong; Sahdan, Mohd Zainizan; Lias, Jais; Wibowo, Kusnanto Mukti; Bakar, Ahmad Shuhaimi Abu; Arshad, Mohd Khairuddin Md; Hashim, Uda; Nayan, Nafarizal

    2017-09-01

    Inactivation of bacteria or sterilization has been a major issue in the medical field, especially regarding of human safety, whereby, in a huge scenario fatality can be caused by hazardous bacteria. Often, E-coli as gram-negative bacteria are selected as a key indicator of proper sterilization process as E-coli is tough and dormant bacteria. The technology in sterilization has moved on from chemical, wet and irradiation sterilization to a high promising device such as atmospheric pressure plasma needle jet (APPNJ). It has been reported that atmospheric pressure plasma has provided bundle of advantages over earlier sterilization process. The APPNJ is developed in our lab using high frequency and high voltage neon transformer power supply connected to copper needle and copper sheet electrodes. The gas discharge is Ar gas flowing at 40 L/min through a quartz glass tube. The E-coli bacteria are self-cultured from waste water and then treated with APPNJ. The treatment processes are run into two difference gaps between the plasma orifice and sample with various treatment times. Only 40s is required by direct treatment to achieve 100% killing of E-coli. On the other hand, indirect treatment has inactivated 50% of the E-coli in 40s. In this study, direct and indirect effect of APPNJ to the E-coli can be observed which can be utilized into sterilization of bio-compatible material applications.

  2. Compact atmospheric pressure plasma self-resonant drive circuits

    Science.gov (United States)

    Law, V. J.; Anghel, S. D.

    2012-02-01

    This paper reports on compact solid-state self-resonant drive circuits that are specifically designed to drive an atmospheric pressure plasma jet and a parallel-plate dielectric barrier discharge of small volume (0.5 cm3). The atmospheric pressure plasma (APP) device can be operated with helium, argon or a mixture of both. Equivalent electrical models of the self-resonant drive circuits and discharge are developed and used to estimate the plasma impedance, plasma power density, current density or electron number density of three APP devices. These parameters and the kinetic gas temperature are dependent on the self-resonant frequency of the APP device. For a fixed switching frequency and APP device geometry, the plasma parameters are controlled by adjusting the dc voltage at the primary coil and the gas flow rate. The resonant frequency is controlled by the selection of the switching power transistor and means of step-up voltage transformation (ferrite core, flyback transformer, or Tesla coil). The flyback transformer operates in the tens of kHz, the ferrite core in the hundreds of kHz and Tesla coil in the MHz range. Embedded within this work is the principle of frequency pulling which is exemplified in the flyback transformer circuit that utilizes a pickup coil for feedback control of the switching frequency.

  3. Atmospheric-pressure plasma decontamination/sterilization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Hans W. (Los Alamos, NM); Selwyn, Gary S. (Los Alamos, NM)

    2001-01-01

    An atmospheric-pressure plasma decontamination/sterilization chamber is described. The apparatus is useful for decontaminating sensitive equipment and materials, such as electronics, optics and national treasures, which have been contaminated with chemical and/or biological warfare agents, such as anthrax, mustard blistering agent, VX nerve gas, and the like. There is currently no acceptable procedure for decontaminating such equipment. The apparatus may also be used for sterilization in the medical and food industries. Items to be decontaminated or sterilized are supported inside the chamber. Reactive gases containing atomic and metastable oxygen species are generated by an atmospheric-pressure plasma discharge in a He/O.sub.2 mixture and directed into the region of these items resulting in chemical reaction between the reactive species and organic substances. This reaction typically kills and/or neutralizes the contamination without damaging most equipment and materials. The plasma gases are recirculated through a closed-loop system to minimize the loss of helium and the possibility of escape of aerosolized harmful substances.

  4. Reactivity zones around an atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Birer, Özgür, E-mail: obirer@ku.edu.tr

    2015-11-01

    Highlights: • Polyethylene surfaces were treated with atmospheric pressure cold plasma jet. • The effect of plasma extends beyond the physical jet diameter. • Moieties of –NO, –COO, –CO and –NO{sub 3} as expanding ring patterns were detected. • Active species in the plasma are identified for specific surface moieties. - Abstract: The reactivity zones around an atmospheric pressure plasma jet are revealed by XPS mapping of chemical moieties on a polyethylene surface treated with a 3-mm plasma jet. The area directly hit by the helium plasma jet initially oxidizes and later etches away as the plasma treatment continues. The oxidation initially starts at the center and expands outwards as a ring pattern with different spatial potency. At the end of 10 min plasma jet treatment, distinct ring patterns for –NO, –COO, –CO and –NO{sub 3} species can be detected with respectively increasing diameters. The plasma jet can cause chemical changes at locations several millimeters away from the center. The spatial distribution of oxidized species suggests presence of chemical reactivity zones. Introduction of nitrogen into the helium plasma jet, not only increases the type of nitrogen moieties, but enriches the reactivity zones by generating nitrogen molecular ions within the plasma jet. The complex competing reaction mechanisms among the radicals, ions, metastable atoms and UV photons lead to unusual etching patterns on the surfaces.

  5. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  6. The major influence of the atmosphere on intracranial pressure: an observational study

    Science.gov (United States)

    Herbowski, Leszek

    2017-01-01

    The impact of the atmosphere on human physiology has been studied widely within the last years. In practice, intracranial pressure is a pressure difference between intracranial compartments and the surrounding atmosphere. This means that gauge intracranial pressure uses atmospheric pressure as its zero point, and therefore, this method of pressure measurement excludes the effects of barometric pressure's fluctuation. The comparison of these two physical quantities can only take place through their absolute value relationship. The aim of this study is to investigate the direct effect of barometric pressure on the absolute intracranial pressure homeostasis. A prospective observational cross-sectional open study was conducted in Szczecin, Poland. In 28 neurosurgical patients with suspected normal-pressure hydrocephalus, intracranial intraventricular pressure was monitored in a sitting position. A total of 168 intracranial pressure and atmospheric pressure measurements were performed. Absolute atmospheric pressure was recorded directly. All values of intracranial gauge pressure were converted to absolute pressure (the sum of gauge intracranial pressure and local absolute atmospheric pressure). The average absolute mean intracranial pressure in the patients is 1006.6 hPa (95 % CI 1004.5 to 1008.8 hPa, SEM 1.1), and the mean absolute atmospheric pressure is 1007.9 hPa (95 % CI 1006.3 to 1009.6 hPa, SEM 0.8). The observed association between atmospheric and intracranial pressure is strongly significant (Spearman correlation r = 0.87, p pressure are related to seasonal variation. Absolute intracranial pressure is shown to be impacted positively by atmospheric pressure.

  7. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    Science.gov (United States)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from peel ply. After oxygen plasma activation and joining the materials together with epoxy, one observes 100% cohesive failure within the cured film adhesive. Depending on the material, the lap shear strength can be increased several fold over that achieved by either solvent wiping or abrasion. The trends in adhesion with plasma exposure time do not correlate well with surface wetting or roughness; instead they correlate with the fraction of the polymer surface sites that are converted into carboxylic acid groups.

  8. Evaluation of the impact of atmospheric pressure in different seasons on blood pressure in patients with arterial hypertension

    National Research Council Canada - National Science Library

    Kamiński, Marek; Cieślik-Guerra, Urszula I; Kotas, Rafał; Mazur, Piotr; Marańda, Witold; Piotrowicz, Maciej; Sakowicz, Bartosz; Napieralski, Andrzej; Trzos, Ewa; Uznańska-Loch, Barbara; Rechciński, Tomasz; Kurpesa, Małgorzata

    2016-01-01

    .... The main objective of our research was to assess the relationship between atmospheric pressure recorded with a frequency of 1 measurement per minute and the results of 24-h blood pressure monitoring...

  9. Properties of arrays of microplasmas: application to control of electromagnetic waves

    Science.gov (United States)

    Qu, Chenhui; Tian, Peng; Semnani, Abbas; Kushner, Mark J.

    2017-10-01

    Microplasma arrays (MAs) are being investigated as a method to control the propagation of electromagnetic waves. The use of MAs as an electromagnetic wave controlling material is attractive as the electrical properties of MAs can be rapidly changed through combinations of the choice of operating conditions (e.g. pressure, gas mixture), the spatial distribution of the plasma and applied voltage waveforms. In this paper, results from a computational investigation of the plasma properties of small arrays of microplasmas are discussed. The model systems are arrays of microplasmas sustained in rare gases at pressures of up to 100 Torr in a sealed chamber. Individual plasma cells are ≈100 μm in size. Pulsed dc voltage waveforms having widths of 30 ns are applied at repetition rates of up to 10 MHz. The cross-talk between plasma cells was investigated, as well as the consequences of gas heating and sequencing of the pulses. We found that even without physical barriers between the plasma cells to control cross-talk between cells, the individual character of each cell can be retained; however the plasma cells were not completely independent. The diffusion of metastable excited atomic states and small fluxes of ions did enable adjacent cells to operate at lower voltages. The ability to control microwave propagation through waveguides was computationally investigated by placing a MA inside a standard waveguide and examining the resulting transmission coefficients. We found that for frequencies of tens to 100 GHz, the transmitted power could be controlled by the spatial distribution of the MA cells with respect to the modal structure of the wave.

  10. Operating principles of microplasmas assisted by field emitting cathodes

    Science.gov (United States)

    Venkattraman, Ayyaswamy

    2016-09-01

    Microplasmas have contributed to an exciting new direction in low-temperature plasma science and engineering with various applications including electronics, nanomaterial synthesis, and lighting to name a few. The rapid miniaturization of microplasma devices has provided the opportunity to exploit physical mechanisms that are considered unimportant in traditional macroscale plasmas. Specifically, the intense electric fields encountered in microplasma devices lead to an auxiliary source of electrons via field-induced electron emission from the electrodes. Also, recent advances in nano/microfabrication have resulted in the engineering of thin film materials (such as ultrananocrystalline diamond) with field emission threshold electric fields as low as 1 V / μm thereby allowing us to exploit them in microplasmas with dimensions 100 μm . In this regard, this talk deals with the principles that govern the operation of microplasma devices assisted by field emitting cathodes. Specifically, the talk will focus on the interesting interplay between field emission and the corresponding microplasma properties with surface-normal electric field serving as the link. Results are presented for the operating modes of field emission assisted microplasmas in the direct current and radio frequency/microwave regimes. The one-dimensional analyses include a combination of simplified global/spatial sheath models, fluid simulations as well as kinetic simulations using the particle-in-cell with Monte Carlo collisions (PIC-MCC) method. Two-dimensional fluid simulations are also presented for microcavity plasmas augmented by field emitting cathodes. The simulations are validated with experimental data whenever possible and a need for additional suitable experimental datasets is highlighted.

  11. Use of Atmospheric Pressure Cold Plasma for Meat Industry.

    Science.gov (United States)

    Lee, Juri; Lee, Cheol Woo; Yong, Hae In; Lee, Hyun Jung; Jo, Cheorun; Jung, Samooel

    2017-01-01

    Novel, effective methods to control and prevent spoilage and contamination by pathogenic microorganisms in meat and meat products are in constant demand. Non-thermal pasteurization is an ideal method for the preservation of meat and meat products because it does not use heat during the pasteurization process. Atmospheric pressure cold plasma (APCP) is a new technology for the non-thermal pasteurization of meat and meat products. Several recent studies have shown that APCP treatment reduces the number of pathogenic microorganisms in meat and meat products. Furthermore, APCP treatment can be used to generate nitrite, which is an essential component of the curing process. Here, we introduce the effectiveness of APCP treatment as a pasteurization method and/or curing process for use in the meat and meat product processing industry.

  12. Atmospheric pressure dielectric barrier discharges for sterilization and surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chin, O. H.; Lai, C. K.; Choo, C. Y.; Wong, C. S.; Nor, R. M. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Thong, K. L. [Microbiology Division, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Atmospheric pressure non-thermal dielectric barrier discharges can be generated in different configurations for different applications. For sterilization, a parallel-plate electrode configuration with glass dielectric that discharges in air was used. Gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and Gram-positive bacteria (Bacillus cereus) were successfully inactivated using sinusoidal high voltage of ∼15 kVp-p at 8.5 kHz. In the surface treatment, a hemisphere and disc electrode arrangement that allowed a plasma jet to be extruded under controlled nitrogen gas flow (at 9.2 kHz, 20 kVp-p) was applied to enhance the wettability of PET (Mylar) film.

  13. Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

    Science.gov (United States)

    Korolev, Yu. D.; Frants, O. B.; Nekhoroshev, V. O.; Suslov, A. I.; Kas'yanov, V. S.; Shemyakin, I. A.; Bolotov, A. V.

    2016-06-01

    Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

  14. Atmospheric pressure vapour phase decomposition: a proof of principle.

    Science.gov (United States)

    Cinosi, Amedeo; Andriollo, Nunzio; Tibaldi, Francesca; Monticelli, Damiano

    2012-11-15

    In the present work we demonstrated that the digestion of difficult matrices (high boiling petrochemical fractions and distillation bottoms) can be achieved by oxidation with nitric acid vapours at atmospheric pressure employing simple laboratory glassware. The application of this procedure as a digestion method prior to Total Reflection X-Ray Fluorescence (TXRF) is presented, although the employment of other detection techniques may be foreseen. The method ensured a fast, less than half an hour, treatment time and detection limits in the range 20-100 μg/kg for As, Bi, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Zn, whereas higher values were obtained for Ba, Ca, K, P, Rh, Ti and V (0.3-3 mg/kg). The potentialities and limitations of this procedure were discussed: the application to a broad range of matrices may be foreseen. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

    Science.gov (United States)

    Setareh, Salarieh; Davoud, Dorranian

    2013-11-01

    In this study atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/O2, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 min is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.

  16. Diagnostics of atmospheric pressure capillary DBD oxygen plasma jet

    CERN Document Server

    Roy, N C; Pramanik, B K

    2015-01-01

    Atmospheric pressure capillary dielectric barrier oxygen discharge plasma jet is developed to generate non-thermal plasma using unipolar positive pulse power supply. Both optical and electrical techniques are used to investigate the characteristics of the produced plasma as function of applied voltage and gas flow rate. Analytical results obtained from the optical emission spectroscopic data reveal the gas temperature, rotational temperature, excitation temperature and electron density. Gas temperature and rotational temperature are found to decrease with increasing oxygen flow rate but increase linearly with applied voltage. It is exposed that the electron density is boosting up with enhanced applied voltage and oxygen flow rate, while the electron excitation temperature is reducing with rising oxygen flow rate. Electrical characterization demonstrates that the discharge frequency is falling with flow rate but increasing with voltage. The produced plasma is applied preliminarily to study the inactivation yie...

  17. Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry.

    Science.gov (United States)

    Colizza, Kevin; Mahoney, Keira E; Yevdokimov, Alexander V; Smith, James L; Oxley, Jimmie C

    2016-11-01

    Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression. Graphical Abstract ᅟ.

  18. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    Science.gov (United States)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1δg), and 2.9 x 10^12 cm-3 O2(^1σ^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1δg) metastables were responsible for killing the anthrax and other microorganisms.

  19. Trends in surface engineering of biomaterials: atmospheric pressure plasma deposition of coatings for biomedical applications

    Science.gov (United States)

    da Ponte, G.; Sardella, E.; Fanelli, F.; D'Agostino, R.; Favia, P.

    2011-11-01

    Cold plasma processes for surface engineering of biomaterials and biomedical devices are traditionally performed at low pressure; more and more, though, surface modification plasma processes at atmospheric pressure are also gaining popularity. This short review is aimed to list briefly atmospheric pressure plasma processes reported, in the last decade, for adapting the surface of materials to the best interactions with cells, bacteria and biomolecules.

  20. Ionization of EPA Contaminants in Direct and Dopant-Assisted Atmospheric Pressure Photoionization and Atmospheric Pressure Laser Ionization

    Science.gov (United States)

    Kauppila, Tiina J.; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

  1. Isotope ratio characteristics and sensitivity for uranium determinations using a liquid sampling-atmospheric pressure glow discharge ion source coupled to an Orbitrap mass analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.; Hart, Garret L.; Koppenaal, David W.; Marcus, R. Kenneth

    2016-01-01

    Abstract The continued development of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma as an ion source for diverse, elemental/isotopic analysis applications continues. To this end, characterization of the capabilities in performing precise and accurate isotope ratio (IR) determinations is essential. Based on past experience with the Thermo Exactive Orbitrap mass analyzer, the LS-APGD was interfaced with this instrument for these tests. While the Orbitrap platform has demonstrated excellent mass resolution and accuracy in “organic” mass spectrometry (MS) applications, work using an Orbitrap for IR analysis is very sparse. These efforts build off previous work in this coupling, where the importance of a few of the LS-APGD discharge parameters and Orbitrap data acquisition methods on IR precision and accuracy were probed. Presented here are the results of a study that evaluated the analytical precision for natural uranium sample (assumed 235U/238U = 0.0072) determinations. The instrumental parameters evaluated include the number of microscans and scans making up a data acquisition set, uranium concentration/signal level, sample make-up, and Fourier transform digitization window. Ultimately, a precision of 0.41% relative standard deviation (RSD) can be achieved for a single determination, with a reproducibility of 1.63 %RSD over 10 separate analytical measurements. A preliminary study of matrix effects on IR measurements of U is presented, highlighting the importance of pre-mass selection before injection into the Orbitrap. The analytical system sensitivity is suggested with the ability to produce a calibration function having an R2 value of >0.99 over a range of 4 orders of magnitude of concentration (~1 – 1000 ng mL-1). These efforts demonstrate the very promising pairing of the LS-APGD ionization source and the Orbitrap, pointing as well to definitive paths forward to better utilize both components in high quality isotope ratio

  2. Use of nonlocal helium microplasma for gas impurities detection by the collisional electron spectroscopy method

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, Anatoly A., E-mail: akud@ak2138.spb.edu [St. Petersburg State University, 7-9 Universitetskaya nab., 199034 St. Petersburg (Russian Federation); Stefanova, Margarita S.; Pramatarov, Petko M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

    2015-10-15

    The collisional electron spectroscopy (CES) method, which lays the ground for a new field for analytical detection of gas impurities at high pressures, has been verified. The CES method enables the identification of gas impurities in the collisional mode of electron movement, where the advantages of nonlocal formation of the electron energy distribution function (EEDF) are fulfilled. Important features of dc negative glow microplasma and probe method for plasma diagnostics are applied. A new microplasma gas analyzer design is proposed. Admixtures of 0.2% Ar, 0.6% Kr, 0.1% N{sub 2}, and 0.05% CO{sub 2} are used as examples of atomic and molecular impurities to prove the possibility for detecting and identifying their presence in high pressure He plasma (50–250 Torr). The identification of the particles under analysis is made from the measurements of the high energy part of the EEDF, where maxima appear, resulting from the characteristic electrons released in Penning reactions of He metastable atoms with impurity particles. Considerable progress in the development of a novel miniature gas analyzer for chemical sensing in gas phase environments has been made.

  3. Application of atmospheric pressure plasma in polymer and composite adhesion

    Science.gov (United States)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  4. High Pressure Atmospheric Sampling Inlet System for Venus or the Gas Giants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a miniaturized high pressure atmospheric sampling inlet system for sample acquisition in extreme planetary environments,...

  5. Study of short atmospheric pressure dc glow microdischarge in air

    Science.gov (United States)

    Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey

    2011-10-01

    The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen

  6. Influence of atmospheric pressure on the incidence of spontaneous pneumothorax.

    Science.gov (United States)

    Díaz, Raúl; Díez, Manuel Mariano; Medrano, María José; Vera, Cristina; Guillamot, Paloma; Sánchez, Ana; Ratia, Tomás; Granell, Javier

    2014-01-01

    This study analyses the relationship between the incidence of idiopathic spontaneous pneumothorax (ISP) and atmospheric pressure (AP). A total of 288 cases of ISP were included, 229 men and 59 women. The AP of the day of diagnosis, of the 3 prior days and the monthly average was registered. The association between the incidence of ISP and AP was analyzed by calculating standardized incidence ratio (SIR) and Poisson regression. The AP on the day of admission (mean±standard deviation) (1,017.9±7 hectopascals [hPa]) was higher than the monthly average AP (1,016.9±4.1 hPa) (P=.005). There was a monthly distribution pattern of ISP with the highest incidence in the months of January, February and September and the lowest in April. When AP was less than 1,014 hPa, there were fewer cases registered than what would statistically have been expected (58/72 cases). In contrast, when the pressure was higher than 1,019 hPa, the registered cases were more than expected (109/82 cases) (SIR=1.25; 95% CI: 1.04 to 1.51). The risk of ISP increased 1.15 times (95% CI: 1.05 to 1.25, P=.001) for each hPa of AP, regardless of sex, age and monthly average AP. A dose-response relationship was observed, with progressive increases in risk (IRR=1.06 when the AP was 1,014-1016 hPa; 1.17 hPa when the AP was 1,016-1,019 hPa and 1.69 when AP was superior to 1,019 hPa) (P for trend=.089). The AP is a risk factor for the onset of idiopathic spontaneous pneumothorax. Copyright © 2012 AEC. Published by Elsevier Espana. All rights reserved.

  7. Electric discharge microplasmas generated in highly fluctuating fluids: Characteristics and application to the synthesis of molecular diamond

    Science.gov (United States)

    Stauss, Sven

    2014-10-01

    Plasma-based fabrication of novel nanomaterials and nanostructures is paramount for the development of next-generation electronic devices and for green energy applications. In particular, controlling the interactions between plasmas and materials interfaces, and the plasma fluctuations are crucial for further development of plasma-based processes and bottom-up growth of nanomaterials. Discharge microplasmas generated in supercritical fluids represent a special class of high-pressure plasmas, where fluctuations on the molecular scale influence the discharge properties and the possible bottom-up growth of nanomaterials. In the first part of the talk, we will discuss an anomaly observed for microplasmas generated near the critical point, a local decrease in the breakdown voltage, which has been observed for both molecular and monoatomic gases. This anomalous behavior is suggested to be caused by the concomitant decrease of the ionization potential due to the formation of clusters near the critical point, and the formation of extended electron mean free paths induced by the high-density fluctuation near the critical point. We will also show that when generating microplasma discharges close to the critical point, that the high-density fluctuation of the supercritical fluid persists. In the second part of the presentation, we will first introduce the basic properties of diamondoids and their potential for application in many different fields - biotechnology, medicine, opto- and nanoelectronics - before discussing their synthesis by microplasmas generated inside both conventional batch-type and continuous flow reactors, using the smallest diamondoid, adamantane, as a precursor and seed. Finally we show that one possible growth mechanism of larger diamondoids from smaller ones consists in the repeated abstraction of hydrogen terminations and the addition of methyl radicals. Supported financially in part by Grant No. 23760688 and Grant No. 21110002 from the Ministry of

  8. Blow-out limits of nonpremixed turbulent jet flames in a cross flow at atmospheric and sub-atmospheric pressures

    KAUST Repository

    Wang, Qiang

    2015-07-22

    The blow-out limits of nonpremixed turbulent jet flames in cross flows were studied, especially concerning the effect of ambient pressure, by conducting experiments at atmospheric and sub-atmospheric pressures. The combined effects of air flow and pressure were investigated by a series of experiments conducted in an especially built wind tunnel in Lhasa, a city on the Tibetan plateau where the altitude is 3650 m and the atmospheric pressure condition is naturally low (64 kPa). These results were compared with results obtained from a wind tunnel at standard atmospheric pressure (100 kPa) in Hefei city (altitude 50 m). The size of the fuel nozzles used in the experiments ranged from 3 to 8 mm in diameter and propane was used as the fuel. It was found that the blow-out limit of the air speed of the cross flow first increased (“cross flow dominant” regime) and then decreased (“fuel jet dominant” regime) as the fuel jet velocity increased in both pressures; however, the blow-out limit of the air speed of the cross flow was much lower at sub-atmospheric pressure than that at standard atmospheric pressure whereas the domain of the blow-out limit curve (in a plot of the air speed of the cross flow versus the fuel jet velocity) shrank as the pressure decreased. A theoretical model was developed to characterize the blow-out limit of nonpremixed jet flames in a cross flow based on a Damköhler number, defined as the ratio between the mixing time and the characteristic reaction time. A satisfactory correlation was obtained at relative strong cross flow conditions (“cross flow dominant” regime) that included the effects of the air speed of the cross flow, fuel jet velocity, nozzle diameter and pressure.

  9. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    Directory of Open Access Journals (Sweden)

    Natalie R. Danna

    2015-01-01

    Full Text Available This study assessed the osseointegrative effects of atmospheric pressure plasma (APP surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti and calcium phosphate (CaP. Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC and bone area fraction occupancy (BAFO were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P<0.001 increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P=0.57 differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted.

  10. Atmospheric pressure plasma accelerates tail regeneration in tadpoles Xenopus laevis

    Science.gov (United States)

    Rivie, A.; Martus, K.; Menon, J.

    2017-08-01

    Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged particles, including electrons and ions, as well as reactive oxygen species (ROS). Recently, it is utilized as possible therapy in oncology, sterilization, skin diseases, wound healing and tissue regeneration. In this study we focused on effect of plasma exposure on tail regeneration of tadpoles, Xenopus leavis with special emphasis on role of ROS, antioxidant defenses and morphological features of the regenerate. When amputated region of the tail was exposed to the helium plasma it resulted in a faster rate of growth, elevated ROS and increase in antioxidant enzymes in the regenerate compared to that of untreated control. An increase in nitric oxide (free radical) as well as activity of nitric oxide synthase(s) were observed once the cells of the regeneration blastema - a mass of proliferating cells are ready for differentiation. Microscopically the cells of the regenerate of plasma treated tadpoles show altered morphology and characteristics of cellular hypoxia and oxidative stress. We summarize that plasma exposure accelerates the dynamics of wound healing and tail regeneration through its effects on cell proliferation and differentiation as well as angiogenesis mediated through ROS signaling.

  11. Searching for order in atmospheric pressure plasma jets

    Science.gov (United States)

    Schäfer, Jan; Sigeneger, Florian; Šperka, Jiří; Rodenburg, Cornelia; Foest, Rüdiger

    2018-01-01

    The self-organized discharge behaviour occurring in a non-thermal radio-frequency plasma jet in rare gases at atmospheric pressure was investigated. The frequency of the azimuthal rotation of filaments in the active plasma volume and their inclination were measured along with the gas temperature under varying discharge conditions. The gas flow and heating were described theoretically by a three-dimensional hydrodynamic model. The rotation frequencies obtained by both methods qualitatively agree. The results demonstrate that the plasma filaments forming an inclination angle α with the axial gas velocity u z are forced to a transversal movement with the velocity {u}φ =\\tan (α )\\cdot {u}z, which is oriented in the inclination direction. Variations of {u}φ in the model reveal that the observed dynamics minimizes the energy loss due to convective heat transfer by the gas flow. The control of the self-organization regime motivates the application of the plasma jet for precise and reproducible material processing.

  12. Dynamics of apokamp-type atmospheric pressure plasma jets

    Science.gov (United States)

    Sosnin, Eduard A.; Panarin, Victor A.; Skakun, Victor S.; Baksht, Evgeny Kh.; Tarasenko, Victor F.

    2017-02-01

    The paper describes a new discharge source of atmospheric pressure plasma jets (APPJs) in air with no gas supply through the discharge region. In this discharge mode, plasma jets develop from the bending point of a bright current channel between two electrodes and are therefore termed an apokamp (from Greek `off' and `bend'). The apokamp can represent single plasma jets of length up 6 cm or several jets, and the temperature of such jets can range from more than 1000 °C at their base to 100-250 °C at their tip. Apokamps are formed at maximum applied voltage of positive polarity, provided that the second electrode is capacitively decoupled with ground. According to high-speed photography with time resolution from several nanoseconds to several tens of nanoseconds, the apokamp consists of a set of plasma bullets moving with a velocity of 100-220 km/s, which excludes the convective mechanism of plasma decay. Estimates on a 100-ns scale show that the near-electrode zones and the zones from which apokamps develop are close in temperature.

  13. The solvation of electrons by an atmospheric-pressure plasma

    Science.gov (United States)

    Rumbach, Paul; Bartels, David M.; Sankaran, R. Mohan; Go, David B.

    2015-01-01

    Solvated electrons are typically generated by radiolysis or photoionization of solutes. While plasmas containing free electrons have been brought into contact with liquids in studies dating back centuries, there has been little evidence that electrons are solvated by this approach. Here we report direct measurements of solvated electrons generated by an atmospheric-pressure plasma in contact with the surface of an aqueous solution. The electrons are measured by their optical absorbance using a total internal reflection geometry. The measured absorption spectrum is unexpectedly blue shifted, which is potentially due to the intense electric field in the interfacial Debye layer. We estimate an average penetration depth of 2.5±1.0 nm, indicating that the electrons fully solvate before reacting through second-order recombination. Reactions with various electron scavengers including H+, NO2−, NO3− and H2O2 show that the kinetics are similar, but not identical, to those for solvated electrons formed in bulk water by radiolysis. PMID:26088017

  14. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    Science.gov (United States)

    Danna, Natalie R.; Beutel, Bryan G.; Tovar, Nick; Witek, Lukasz; Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Coelho, Paulo G.

    2015-01-01

    This study assessed the osseointegrative effects of atmospheric pressure plasma (APP) surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti) and calcium phosphate (CaP). Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total) was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P < 0.001) increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P = 0.57) differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted. PMID:26090443

  15. Atmospheric pressure arc discharge with ablating graphite anode

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, V. A. [Keiser University, Fort Lauderdale Campus, FL, 33309, USA; Raitses, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2015-05-18

    The anodic carbon arc discharge is used to produce carbon nanoparticles. Recent experiments with the carbon arc at atmospheric pressure helium demonstrated the enhanced ablation rate for narrow graphite anodes resulting in high deposition rates of carbonaceous products on the copper cathode (Fetterman et al 2008 Carbon 46 1322–6). The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes. When considering cathode functioning, the model predicts circulation of the particles in the near-cathode region: evaporation of the cathode material, ionization of evaporated atoms and molecules in the near-cathode plasma, return of the resulting ions to the cathode, surface recombination of ions and electrons followed again by cathode evaporation etc. In the case of the low anode ablation rate, the ion acceleration in the cathode sheath provides the major cathode heating mechanism. In the case of an intensive anode ablation, an additional cathode heating is due to latent fusion heat of the atomic species evaporated from the anode and depositing at the cathode. Using the experimental arc voltage as the only input discharge parameter, the model allows us to calculate the anode ablation rate. A comparison of the results of calculations with the available experimental data shows reasonable agreement.

  16. Hydrocarbon analysis using desorption atmospheric pressure chemical ionization

    KAUST Repository

    Jjunju, Fred Paul Mark

    2013-07-01

    Characterization of the various petroleum constituents (hydronaphthalenes, thiophenes, alkyl substituted benzenes, pyridines, fluorenes, and polycyclic aromatic hydrocarbons) was achieved under ambient conditions without sample preparation by desorption atmospheric pressure chemical ionization (DAPCI). Conditions were chosen for the DAPCI experiments to control whether ionization was by proton or electron transfer. The protonated molecule [M+H]+ and the hydride abstracted [MH]+ form were observed when using an inert gas, typically nitrogen, to direct a lightly ionized plasma generated by corona discharge onto the sample surface in air. The abundant water cluster ions generated in this experiment react with condensed-phase functionalized hydrocarbon model compounds and their mixtures at or near the sample surface. On the other hand, when naphthalene was doped into the DAPCI gas stream, its radical cation served as a charge exchange reagent, yielding molecular radical cations (M+) of the hydrocarbons. This mode of sample ionization provided mass spectra with better signal/noise ratios and without unwanted side-products. It also extended the applicability of DAPCI to petroleum constituents which could not be analyzed through proton transfer (e.g., higher molecular PAHs such as chrysene). The thermochemistry governing the individual ionization processes is discussed and a desorption/ionization mechanism is inferred. © 2012 Elsevier B.V.

  17. The impact of relative humidity and atmospheric pressure on mortality in Guangzhou, China.

    Science.gov (United States)

    Ou, Chun Quan; Yang, Jun; Ou, Qiao Qun; Liu, Hua Zhang; Lin, Guo Zhen; Chen, Ping Yan; Qian, Jun; Guo, Yu Ming

    2014-12-01

    Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impacts of atmospheric pressure and relative humidity on mortality in Guangzhou, China. This study included 213,737 registered deaths during 2003-2011 in Guangzhou, China. A quasi-Poisson regression with a distributed lag non-linear model was used to assess the effects of atmospheric pressure/relative humidity. We found significant effect of low atmospheric pressure/relative humidity on mortality. There was a 1.79% (95% confidence interval: 0.38%-3.22%) increase in non-accidental mortality and a 2.27% (0.07%-4.51%) increase in cardiovascular mortality comparing the 5th and 25th percentile of atmospheric pressure. A 3.97% (0.67%-7.39%) increase in cardiovascular mortality was also observed comparing the 5th and 25th percentile of relative humidity. Women were more vulnerable to decrease in atmospheric pressure and relative humidity than men. Age and education attainment were also potential effect modifiers. Furthermore, low atmospheric pressure and relative humidity increased temperature-related mortality. Both low atmospheric pressure and relative humidity are important risk factors of mortality. Our findings would be helpful to develop health risk assessment and climate policy interventions that would better protect vulnerable subgroups of the population. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  18. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Norberg, Seth A., E-mail: norbergs@umich.edu; Johnsen, Eric, E-mail: ejohnsen@umich.edu [Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan 48109-2125 (United States); Kushner, Mark J., E-mail: mjkush@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109-2122 (United States)

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  19. Hollow needle-to-plate electrical discharge at atmospheric pressure

    Science.gov (United States)

    Pekárek, S.; Kríha, V.; Simek, M.; Bálek, R.; Hanitz, F.

    1999-08-01

    Ecological applications dealing with the cleaning of flue gases, the decomposition of volatile hydrocarbons and the destruction of toxic pollutants require, in order to reach high efficiency, the use of non-thermal plasma sources. Typical sources of such non-equilibrium plasmas are barrier discharge, direct current (DC) or alternating current (AC) gliding arc, pulsed or DC corona and DC atmospheric pressure discharge stabilized by a fast gas flow (APD-GFS). In case of APD-GFS the gas flows in a rectangular channel, the top wall of which serves as the anode and the multi-needle cathode is built into the bottom wall of the channel. In order to prevent the transition to a spark and to stabilize this type of discharge the velocity of the gas should be about 100-200 m s-1 or the discharge current must be limited. To avoid the problem connected with the acceleration of the primary (polluted) gas at such a velocity, the external flow of the primary gas around the needle electrodes can be superimposed by a flow of a secondary gas through the needles. Thus the primary gas need not be accelerated to high velocity and in order to stabilize the discharge a relatively small amount of a secondary gas supplied through the needle is required. This work is therefore focused on the study of the DC APD-GFS in hollow needle-to-plane geometry. The basic electrical characteristics, magnetic noise and integral emission spectra of this type discharge with the flow of nitrogen or air through the needle are given.

  20. Response of the Mediterranean mean sea level to atmospheric pressure forcing

    OpenAIRE

    Le Traon, Pierre-Yves; Gauzelin, P

    1997-01-01

    The response of the Mediterranean mean sea level to atmospheric pressure forcing is analyzed using 3 years of TOPEX/POSEIDON data. Coherence analysis between mean sea level and atmospheric pressure shows a significant departure from a standard inverse barometer effect at frequencies higher than 30 days(-1). At high frequencies the phase difference between sea level and pressure is about 100 degrees, while it should be 180 degrees for a perfect inverse barometer response. This result is in agr...

  1. Driven motion and instability of an atmospheric pressure arc

    Science.gov (United States)

    Karasik, Max

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental are furnace is constructed and operated in air with graphite cathode and steel anode at currents 100--250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes. Experiments are carried out on the response of the are to applied transverse DC and AC (up to ≈1 kHz) magnetic fields. The arc is found to deflect parabolically for DC field and assumes a growing sinusoidal structure for AC field. A simple analytic two-parameter fluid model of the are dynamics is derived, in which the inertia of the magnetically pumped cathode jet balances the applied J⃗xB⃗ force. Time variation of the applied field allows evaluation of the parameters individually. A fit of the model to the experimental data gives a value for the average jet speed an order of magnitude below Maecker's estimate of the maximum jet speed. A spontaneous instability of the same arc is investigated experimentally and modeled analytically. The presence of the instability is found to depend critically on cathode dimensions. For cylindrical cathodes, instability occurs only for a narrow range of cathode diameters. Cathode spot motion is proposed as the mechanism of the instability. A simple fluid model combining the effect of the cathode spot motion and the inertia of the cathode jet successfully describes the arc shape during low amplitude instability. The amplitude of cathode spot motion required by the model is in agreement with measurements. The average jet velocity required is approximately equal to that inferred from the transverse magnetic field experiments. Reasons for spot motion and for cathode

  2. Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

    Science.gov (United States)

    Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

    2015-09-03

    Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. Copyright © 2015. Published by Elsevier B.V.

  3. A lower limit of atmospheric pressure on early Mars inferred from nitrogen and argon isotopic compositions

    Science.gov (United States)

    Kurokawa, Hiroyuki; Kurosawa, Kosuke; Usui, Tomohiro

    2018-01-01

    We examine the history of the loss and replenishment of the Martian atmosphere using elemental and isotopic compositions of nitrogen and noble gases. The evolution of the atmosphere is calculated by taking into consideration various processes: impact erosion and replenishment by asteroids and comets, atmospheric escape induced by solar radiation and wind, volcanic degassing, and gas deposition by interplanetary dust particles. Our model reproduces the elemental and isotopic compositions of N and noble gases (except for Xe) in the Martian atmosphere, as inferred from exploration missions and analyses of Martian meteorites. Other processes such as ionization-induced fractionation, which are not included in our model, are likely to make a large contribution in producing the current Xe isotope composition. Since intense impacts during the heavy bombardment period greatly affect the atmospheric mass, the atmospheric pressure evolves stochastically. Whereas a dense atmosphere preserves primitive isotopic compositions, a thin atmosphere on early Mars is severely influenced by stochastic impact events and following escape-induced fractionation. The onset of fractionation following the decrease in atmospheric pressure is explained by shorter timescales of isotopic fractionation under a lower atmospheric pressure. The comparison of our numerical results with the less fractionated N (15N/14N) and Ar (38Ar/36Ar) isotope compositions of the ancient atmosphere recorded in the Martian meteorite Allan Hills 84001 provides a lower limit of the atmospheric pressure in 4 Ga to preserve the primitive isotopic compositions. We conclude that the atmospheric pressure was higher than approximately 0.5 bar at 4 Ga.

  4. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    Science.gov (United States)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  5. Modeling of microplasmas from GHz to THz

    Science.gov (United States)

    Gregório, J.; Hoskinson, A. R.; Hopwood, J.

    2015-08-01

    We present a study of atmospheric-pressure microdischarges sustained over a wide range of continuous excitation frequencies. A fluid model is used to describe the spatial and temporal evolution of the plasma properties within a 200 μm discharge gap. At 0.5 GHz, the behavior is similar to a typical rf collisional discharge. As frequency increases at constant power density, we observe a decrease in the discharge voltage from greater than 100 V to less than 10 V. A minimum of the voltage amplitude is attained when electron temporal inertia delays the discharge current to be in phase with the applied voltage. Above this frequency, the plasma develops resonant regions where the excitation frequency equals the local plasma frequency. In these volumes, the instantaneous quasi-neutrality is perturbed and intense internal currents emerge ensuring a low voltage operation range. This enhanced plasma heating mechanism vanishes when the excitation frequency is larger than the local plasma frequency everywhere in the plasma volume. For a typical peak electron density of 5 × 10 20 m-3, this condition corresponds to ˜ 0.2 THz. Beyond the plasma frequency, the discharge performs like a low loss dielectric and an increasingly large voltage is necessary to preserve a constant absorbed power.

  6. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    National Research Council Canada - National Science Library

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W; Jeong, Chang-Mo; Jeon, Young-Chan

    2013-01-01

    .... To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated...

  7. MGS RS: ATMOSPHERIC TEMPERATURE-PRESSURE PROFILES V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains over 21000 temperature-pressure profiles (TPS files) of the neutral atmosphere derived from Mars Global Surveyor (MGS) radio occultation data....

  8. Modeling of High-Pressure Turbulent Multi-Species Mixing Applicable to the Venus Atmosphere

    Science.gov (United States)

    Bellan, J.

    2017-11-01

    A comprehensive theory of high-pressure multi-species mixing is presented and salient results pertinent to the Venus atmosphere are discussed. The influence of the insights obtained from these results on Venus exploration are addressed.

  9. Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure

    NARCIS (Netherlands)

    Konakov, S.A.; Krzhizhanovskaya, V.V.

    2015-01-01

    We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis

  10. Water cycles in closed ecological systems: effects of atmospheric pressure.

    Science.gov (United States)

    Rygalov, Vadim Y; Fowler, Philip A; Metz, Joannah M; Wheeler, Raymond M; Bucklin, Ray A

    2002-01-01

    In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from ~1 to 10 L m-2 d-1 (~1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems.

  11. Decontamination of objects in a sealed container by means of atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank; Schultz-Jensen, Nadja; Kusano, Yukihiro

    2011-01-01

    . The ambient atmosphere was air at atmospheric pressure. A plasma is generated inside the bag forming ozone from the oxygen. The maximum ozone concentration in the bag was found to be 140 ppm. A log 6 reduction of L. innocua is obtained after 15 min of exposure time. The temperature of the slides after...

  12. Physiological responses to low atmospheric pressure stunning and the implications for welfare

    NARCIS (Netherlands)

    Mckeegan, D.E.F.; Sandercock, D.A.; Gerritzen, M.A.

    2013-01-01

    In low atmospheric pressure stunning (LAPS), poultry are rendered unconscious before slaughter by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia. The effects of LAPS are not instantaneous, so there are legitimate welfare concerns around the experience of birds

  13. Spectral analysis of optical emission of microplasma in sea water

    Science.gov (United States)

    Gamaleev, Vladislav; Morita, Hayato; Oh, Jun-Seok; Furuta, Hiroshi; Hatta, Akimitsu

    2016-09-01

    This work presents an analysis of optical emission spectra from microplasma in three types of liquid, namely artificial sea water composed of 10 typical agents (10ASW), reference solutions each containing a single agent (NaCl, MgCl2 + H2O, Na2SO4, CaCl2, KCl, NaHCO3, KBr, NaHCO3, H3BO3, SrCl2 + H2O, NaF) and naturally sampled deep sea water (DSW). Microplasma was operated using a needle(Pd)-to-plate(Pt) electrode system sunk into each liquid in a quartz cuvette. The radius of the tip of the needle was 50 μm and the gap between the electrodes was set at 20 μm. An inpulse generator circuit, consisting of a MOSFET switch, a capacitor, an inductor and the resistance of the liquid between the electrodes, was used as a pulse current source for operation of discharges. In the spectra, the emission peaks for the main components of sea water and contaminants from the electrodes were detected. Spectra for reference solutions were examined to enable the identification of unassigned peaks in the spectra for sea water. Analysis of the Stark broadening of H α peak was carried out to estimate the electron density of the plasma under various conditions. The characteristics of microplasma discharge in sea water and the analysis of the optical emission spectra will be presented. This work was supported by JSPS KAKENHI Grant Number 26600129.

  14. High pressure gas laser technology for atmospheric remote sensing

    Science.gov (United States)

    Javan, A.

    1980-01-01

    The development of a fixed frequency chirp-free and highly stable intense pulsed laser made for Doppler wind velocity measurements with accurate ranging is described. Energy extraction from a high pressure CO2 laser at a tunable single mode frequency is also examined.

  15. Self-sustained carbon monoxide oxidation oscillations on size-selected platinum nanoparticles at atmospheric pressure

    DEFF Research Database (Denmark)

    Jensen, Robert; Andersen, Thomas; Nierhoff, Anders Ulrik Fregerslev

    2013-01-01

    High-quality mass spectrometry data of the oscillatory behavior of CO oxidation on SiO2 supported Pt-nanoparticles at atmospheric pressure have been acquired as a function of pressure, coverage, gas composition and nanoparticle size. The oscillations are self-sustained for several days at constan...

  16. Surface modification of polylactic acid films by atmospheric pressure plasma treatment

    Science.gov (United States)

    Kudryavtseva, V. L.; Zhuravlev, M. V.; Tverdokhlebov, S. I.

    2017-09-01

    A new approach for the modification of polylactic acid (PLA) materials using atmospheric pressure plasma (APP) is described. PLA films plasma exposure time was 20, 60, 120 s. The surface morphology and wettability of the obtained PLA films were investigated by atomic force microscopy (AFM) and the sitting drop method. The atmospheric pressure plasma increased the roughness and surface energy of PLA film. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. It was shown that it is possible to obtain PLA films with various surface relief and tunable wettability. Additionally, we demonstrated that the use of cold atmospheric pressure plasma for surface activation allows for the immobilization of bioactive compounds like hyaluronic acid (HA) on the surface of obtained films. It was shown that composite PLA-HA films have an increased long-term hydrophilicity of the films surface.

  17. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  18. Germination and growth of lettuce (Lactuca sativa) at low atmospheric pressure

    Science.gov (United States)

    Spanarkel, Robert; Drew, Malcolm C.

    2002-01-01

    The response of lettuce (Lactuca sativa L. cv. Waldmann's Green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. Growth took place inside a 66-l-volume low pressure chamber maintained at 70 kPa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kPa) as a control. In other experiments, to determine short-term effects of low pressure transients, plants were grown at ambient pressure until maturity and then subjected to alternating periods of 24 h of low and ambient atmospheric pressures. In all treatments the partial pressure of O2 was maintained at 21 kPa (approximately the partial pressure in air at normal pressure), and the partial pressure of CO2 was in the range 66.5-73.5 Pa (about twice that in normal air) in both chambers, with the addition of CO2 during the light phase. With continuous exposure to low pressure, shoot and root growth was at least as rapid as at ambient pressure, with an overall trend towards slightly greater performance at the lower pressure. Dark respiration rates were greater at low pressure. Transient periods at low pressure decreased transpiration and increased dark respiration but only during the period of exposure to low pressure. We conclude that long-term or short-term exposure to subambient pressure (70 kPa) was without detectable detriment to vegetative growth and development.

  19. Liquid chromatography/mass spectrometry in anabolic steroid analysis--optimization and comparison of three ionization techniques: electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization.

    Science.gov (United States)

    Leinonen, Antti; Kuuranne, Tiia; Kostiainen, Risto

    2002-07-01

    The applicability of liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the detection of the free anabolic steroid fraction in human urine was examined. Electrospray ionization (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization methods were optimized regarding eluent composition, ion source parameters and fragmentation. The methods were compared with respect to specificity and detection limit. Although all methods proved suitable, LC/ESI-MS/MS with a methanol-water gradient including 5 mM ammonium acetate and 0.01% acetic acid was found best for the purpose. Multiple reaction monitoring allowed the determination of steroids in urine at low nanogram per milliliter levels. LC/MS/MS exhibited high sensitivity and specificity for the detection of free steroids and may be a suitable technique for screening for the abuse of anabolic steroids in sports. Copyright 2002 John Wiley & Sons, Ltd.

  20. Effect of Atmospheric Pressure Plasma Modification on Polyimide and Adhesive Joining with Titanium

    Science.gov (United States)

    Akram, M.; Jansen, K. M. B.; Ernst, L. J.; Bhowmik, S.; Ajeesh, G.; Ahmed, S.; Chakraborty, D.

    2015-10-01

    This investigation highlights the effect of surface modification on polyimide by atmospheric pressure plasma treatment with different exposure time. Surface modification of polymer by plasma treatment essentially creates physical and chemical changes such as cross-linking and formation of free radicals. It also forms oxygen functionalization in the form of polar groups on polymer surface, hence improving the wetting and adhesion properties. It is observed that surface energy of the polymer increases with increasing exposure time of atmospheric pressure plasma. However, prolonged exposure time of plasma results in deterioration of the surface layer of polyimide resulting in degradation and embrittlement. Scanning electron microscopy and atomic force microscopy analysis reveal that there is a considerable morphological change on the polymer surface due to atmospheric pressure plasma treatment. X-ray photo electron spectroscopy analysis reveals that the oxygen functionalities of polymer surface increases significantly when polyimide is exposed to atmospheric pressure plasma. Untreated and atmospheric pressure plasma-treated polyimide sheet are adhesive bonded by employing polyimide adhesive as well as with titanium substrate. Due to surface modification of polyimide, it is observed that there is a significant increase in lap shear tensile strength, and therefore, this technology is highly acceptable for aviation and space applications.

  1. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    Energy Technology Data Exchange (ETDEWEB)

    Štěpánová, Vlasta, E-mail: vstepanova@mail.muni.cz [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Černák, Mirko [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina F2, 842 48 Bratislava (Slovakia)

    2015-11-15

    Graphical abstract: - Highlights: • Rabbit fibres plasma treatment is an effective method for fibres modification. • Atmospheric pressure plasma treatment is able to affect fibres properties. • Surface changes on fibres after plasma treatment were analysed via SEM, ATR-FTIR, XPS. • Significant increase of fibres wettability after plasma treatment was observed. • Plasma treatment at atmospheric pressure can replace the chemical treatment of fibres. - Abstract: We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.

  2. Microplasma Ionization of Volatile Organics for Improving Air/Water Monitoring Systems On-Board the International Space Station

    Science.gov (United States)

    Bernier, Matthew C.; Alberici, Rosana M.; Keelor, Joel D.; Dwivedi, Prabha; Zambrzycki, Stephen C.; Wallace, William T.; Gazda, Daniel B.; Limero, Thomas F.; Symonds, Josh M.; Orlando, Thomas M.; Macatangay, Ariel; Fernández, Facundo M.

    2016-07-01

    Low molecular weight polar organics are commonly observed in spacecraft environments. Increasing concentrations of one or more of these contaminants can negatively impact Environmental Control and Life Support (ECLS) systems and/or the health of crew members, posing potential risks to the success of manned space missions. Ambient plasma ionization mass spectrometry (MS) is finding effective use as part of the analytical methodologies being tested for next-generation space module environmental analysis. However, ambient ionization methods employing atmospheric plasmas typically require relatively high operation voltages and power, thus limiting their applicability in combination with fieldable mass spectrometers. In this work, we investigate the use of a low power microplasma device in the microhollow cathode discharge (MHCD) configuration for the analysis of polar organics encountered in space missions. A metal-insulator-metal (MIM) structure with molybdenum foil disc electrodes and a mica insulator was used to form a 300 μm diameter plasma discharge cavity. We demonstrate the application of these MIM microplasmas as part of a versatile miniature ion source for the analysis of typical volatile contaminants found in the International Space Station (ISS) environment, highlighting their advantages as low cost and simple analytical devices.

  3. Generation of microwave-excited atmospheric-pressure line plasma and its application

    Science.gov (United States)

    Kuwahata, Hiroshi; Miyata, Hiroshi; Isomura, Masao; Shindo, Haruo

    2017-12-01

    A new 2.45 GHz microwave-excited atmospheric-pressure line plasma system was developed. An atmospheric-pressure helium (He) line plasma with a length of ∼350 mm and a width of ∼6 mm was generated in air at a microwave power of 1100 W. The length of the He line plasma was varied in the range of ∼120–350 mm by changing the width of the waveguide in the microwave tube and the position of the short plunger. When a Si wafer was irradiated with the He line plasma for 10 s, the surface of the Si wafer became superhydrophilic in a belt shape. On the basis of these results, the new microwave-excited atmospheric-pressure He line plasma system was found to be effective for dry cleaning large-area surfaces, such as semiconductor substrates and glass plates used in flat-panel displays.

  4. Generation and control of wide area, homogenous atmospheric pressure discharges for industrial coating applications.

    Science.gov (United States)

    Hynes, Alan; Walter, Castagna; Carr, Kieran; O'Shea, Sean; Herbert, Tony

    2004-09-01

    Dow Corning Plasma Solutions use diffuse atmospheric pressure plasma technology combined with a unique precursor delivery system for a new coatings approach: Atmospheric Pressure Plasma Liquid Deposition. Operating at atmospheric pressure and ambient temperature this process allows the use of a wide range of liquid precursors delivering high chemical functionality onto flexible substrates. Patented APPLD equipment enables plasma deposition onto wide area substrates up to 1.6m width in true reel-to-reel conditions at industrial line speeds up to 30m/min. Substrates can be either electrically insulating or conducting. Recent engineering developments addressing issues in electrode design, liquid delivery and gas retention and distribution, have significantly enhanced the stability and homogeneity of the plasma chemistry and coating performance. The process is controlled through monitoring and control of key plasma chemistry and process parameters. The process hardware and process control package will be described in detail with particular emphasis on plasma chemistry and process control tools.

  5. Atmospheric Pressure Low Temperature Plasma System for Additive Manufacturing

    Science.gov (United States)

    Burnette, Matthew; Staack, David

    2016-09-01

    There is growing interest in using plasmas for additive manufacturing, however these methods use high temperature plasmas to melt the material. We have developed a novel technique of additive manufacturing using a low temperature dielectric barrier discharge (DBD) jet. The jet is attached to the head of a 3D printer to allow for precise control of the plasma's location. Various methods are employed to deposit the material, including using a vaporized precursor or depositing a liquid precursor directly onto the substrate or into the plasma via a nebulizer. Various materials can be deposited including metals (copper using copper (II) acetylacetonate), polymers (PMMA using the liquid monomer), and various hydrocarbon compounds (using alcohols or a 100% methane DBD jet). The rastering pattern for the 3D printer was modified for plasma deposition, since it was originally designed for thermoplastic extrusion. The design constraints for fill pattern selection for the plasma printer are influenced by substrate heating, deposition area, and precursor consumption. Depositions onto pressure and/or temperature sensitive substrates can be easily achieved. Deposition rates range up to 0.08 cm3/hr using tris(2-methoxyethoxy)(vinyl)silane, however optimization can still be done on the system to improve the deposition rate. For example higher concentration of precursor can be combined with faster motion and higher discharge powers to increase the deposition rate without overheating the substrate.

  6. Atmospheric Airborne Pressure Measurements Using the Oxygen A Band for the ASCENDS Mission

    Science.gov (United States)

    Riris, Haris; Rodriguez, Mike; Stephen, Mark; Hasselbrack, William; Allan, Graham; Mao, Jiamping,; Kawa, Stephan R.; Weaver, Clark J.

    2011-01-01

    We report on airborne atmospheric pressure measurements using new fiber-based laser technology and the oxygen A-band at 765 nm. Remote measurements of atmospheric temperature and pressure are required for a number of NASA Earth science missions and specifically for the Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission. Accurate measurements of tropospheric CO2 on a global scale are very important in order to better understand its sources and sinks and to improve predictions on any future climate change. The ultimate goal of a CO2 remote sensing mission, such as ASCENDS, is to derive the CO2 concentration in the atmosphere in terms of mole fraction in unit of parts-per-million (ppmv) with regard to dry air. Therefore, both CO2 and the dry air number of molecules in the atmosphere are needed in deriving this quantity. O2 is a stable molecule and uniformly mixed in the atmosphere. Measuring the O2 absorption in the atmosphere can thus be used to infer the dry air number of molecules and then used to calculate CO2 concentration. With the knowledge of atmospheric water vapor, we can then estimate the total surface pressure needed for CO2 retrievals. Our work, funded by the ESTO IIP program, uses fiber optic technology and non-linear optics to generate 765 nm laser radiation coincident with the Oxygen A-band. Our pulsed, time gated technique uses several on- and off-line wavelengths tuned to the O2 absorption line. The choice of wavelengths allows us to measure the pressure by using two adjacent O2 absorptions in the Oxygen A-band. Our retrieval algorithm fits the O2 lineshapes and derives the pressure. Our measurements compare favorably with a local weather monitor mounted outside our laboratory and a local weather station.

  7. Kinetics of Tomato Peroxidase Inactivation by Atmospheric Pressure Cold Plasma Based on Dielectric Barrier Discharge

    OpenAIRE

    Cullen, Patrick; Pankaj, Shashi; Misra, N

    2013-01-01

    Atmospheric pressure cold plasma technology is an emerging nonthermal food technology for microbiological decontamination of food and bio-materials. This study demonstrates the applicability of in-package cold plasma technology as a novel means to inactivation of enzymes. The kinetics of inactivation of tomato peroxidase as a model enzyme was studied at 30, 40 and 50kV, for up to 5’ of atmospheric air dielectric barrier discharge plasma treatments. The enzyme activity was found to decrease wi...

  8. Atmospheric pressure ionization-tandem mass spectrometry of the phenicol drug family.

    Science.gov (United States)

    Alechaga, Élida; Moyano, Encarnación; Galceran, M Teresa

    2013-11-01

    In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. Copyright © 2013 John Wiley & Sons, Ltd.

  9. High-performance simulations for atmospheric pressure plasma reactor

    Science.gov (United States)

    Chugunov, Svyatoslav

    Plasma-assisted processing and deposition of materials is an important component of modern industrial applications, with plasma reactors sharing 30% to 40% of manufacturing steps in microelectronics production. Development of new flexible electronics increases demands for efficient high-throughput deposition methods and roll-to-roll processing of materials. The current work represents an attempt of practical design and numerical modeling of a plasma enhanced chemical vapor deposition system. The system utilizes plasma at standard pressure and temperature to activate a chemical precursor for protective coatings. A specially designed linear plasma head, that consists of two parallel plates with electrodes placed in the parallel arrangement, is used to resolve clogging issues of currently available commercial plasma heads, as well as to increase the flow-rate of the processed chemicals and to enhance the uniformity of the deposition. A test system is build and discussed in this work. In order to improve operating conditions of the setup and quality of the deposited material, we perform numerical modeling of the plasma system. The theoretical and numerical models presented in this work comprehensively describe plasma generation, recombination, and advection in a channel of arbitrary geometry. Number density of plasma species, their energy content, electric field, and rate parameters are accurately calculated and analyzed in this work. Some interesting engineering outcomes are discussed with a connection to the proposed setup. The numerical model is implemented with the help of high-performance parallel technique and evaluated at a cluster for parallel calculations. A typical performance increase, calculation speed-up, parallel fraction of the code and overall efficiency of the parallel implementation are discussed in details.

  10. Translational, rotational and vibrational temperatures of a gliding arc discharge at atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2014-01-01

    Gliding arc discharges have generally been used to generate non-equilibrium plasma at atmospheric pressure. Temperature distributions of a gliding arc are of great interest both for fundamental plasma research and for practical applications. In the presented studies, translational, rotational...... and vibrational temperatures of a gliding arc generated at atmospheric pressure air are investigated. Translational temperatures (about 1100 K) were measured by laser-induced Rayleigh scattering, and two-dimensional temperature imaging was performed. Rotational and vibrational temperatures (about 3600 K and 6700...

  11. Use of Atmospheric-Pressure Plasma Jet for Polymer Surface Modification: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-16

    Atmospheric-pressure plasma jets (APPJs) are playing an increasingly important role in materials processing procedures. Plasma treatment is a useful tool to modify surface properties of materials, especially polymers. Plasma reacts with polymer surfaces in numerous ways thus the type of process gas and plasma conditions must be explored for chosen substrates and materials to maximize desired properties. This report discusses plasma treatments and looks further into atmospheric-pressure plasma jets and the effects of gases and plasma conditions. Following the short literature review, a general overview of the future work and research at Los Alamos National Laboratory (LANL) is discussed.

  12. Design of a laboratory platform for atmospheric pressure biomedical plasma experiments

    Science.gov (United States)

    Lee, Sarah; Rutz, Sara; Hicks, Nathaniel; Briggs, Brandon

    2017-10-01

    The design of a laboratory set up for atmospheric pressure plasma (APP) experiments with biomedical applications is described. A comparison between various types of cold APP discharges (DC, RF, microwave) is presented, as well as various configurations of electrodes, dielectric materials, and gas feed conditions. Particular attention is paid to designs comprising floating electrode dielectric barrier discharges (FE-DBD) (for example as described in), but atmospheric pressure plasma jets are considered as well. A plan is discussed for initial experiments on the response of bacterial populations of E. coli and Deinococcus radiodurans to APP treatment as well as to media activated by APP. Supported by 2017 University of Alaska Anchorage Innovate Award.

  13. Melt-vapor phase transition in the lead-selenium system at atmospheric and low pressure

    Science.gov (United States)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.

    2016-03-01

    The boiling temperature and the corresponding vapor phase composition in the existence domain of liquid solutions were calculated from the partial pressures of saturated vapor of the components and lead selenide over liquid melts in the lead-selenium system. The phase diagram was complemented with the liquid-vapor phase transition at atmospheric pressure and in vacuum of 100 Pa, which allowed us to judge the behavior of the components during the distillation separation.

  14. Quantitative emission from femtosecond microplasmas for laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taschuk, M T; Kirkwood, S E; Tsui, Y Y; Fedosejevs, R [Department of Electical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6H 2V4 (Canada)

    2007-04-15

    An ongoing study of the scaling of Laser-Induced Breakdown Spectroscopy (LIBS) to microjoule pulse energies is being conducted to quantify the LIBS process. The use of microplasmas for LIBS requires good understanding of the emission scaling in order to maximize the sensitivity of the LIBS technique at low energies. The quantitative scaling of emission of Al, Cu and Si microplasmas from 100 {mu}J down to 100 nJ is presented. The scaling of line emission from major and minor constituents in Al 5052 alloy is investigated and evaluated for analytical LIBS. Ablated crater volume scaling and emission efficiency for Si microplasmas are investigated.

  15. Chemical detoxification of trichloroethylene and 1,1,1-trichloroethane in a microwave discharge plasma reactor at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Krause, T.R.; Helt, J.E.

    1991-12-31

    This report focuses on the application of plasma technology to hazardous waste treatment. Microwave sustained plasmas are used to thermal degrade trichloroethylene and trichloroethane at atmospheric pressure. (JL)

  16. Atmospheric pressure photoionisation : An ionization method for liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Robb, DB; Covey, TR; Bruins, AP

    2000-01-01

    Atmospheric pressure photoionization (APPI) has been successfully demonstrated to provide high sensitivity to LC-MS analysis. A vacuum-ultraviolet lamp designed for photoionization detection in gas chromatography is used as a source of 10-eV photons. The mixture of samples and solvent eluting from

  17. Real-Time Flavor Release from French Fries Using Atmospheric Pressure Chemical Ionization-Mass Spectrometry

    NARCIS (Netherlands)

    Loon, W.A.M.; Linssen, J.P.H.; Boelrijk, A.E.M.; Burgering, M.J.M.; Voragen, A.G.J.

    2005-01-01

    Flavor release from French fries was measured with atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) using both assessors (in vivo) and a mouth model system (in vitro). Several volatiles measured with APCI were identified with MS-MS. The effect of frying time, salt addition, and

  18. Characterization of typical chemical background interferences in atmospheric pressure ionization liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Guo, Xinghua; Bruins, Andries P.; Covey, Thomas R.

    2006-01-01

    The structures and origins of typical chemical background noise ions in positive atmospheric pressure ionization liquid chromatography/mass spectrometry (API LC/MS) are investigated and summarized in this study. This was done by classifying chemical background ions using precursor and product ion

  19. Atmospheric pressure deposition of SnO2 and ZnO

    NARCIS (Netherlands)

    Deelen, J. van; Kniknie, B.J.; Grob, F.T.J.; Volintiru, I.; Roozeboom, F.; Poodt, P.W.G.; Illiberi, A.

    2012-01-01

    Transparent conductive oxide (TCO) coated glass is widely used in thin film PV. Atmospheric pressure chemical vapor deposition (APCVD) is a highly cost effective method of deposition and apart from metal precursor and oxygen precursor, other additives can improve the layer quality. In this

  20. Cold atmospheric pressure plasma treatment of ready-to-eat meat

    DEFF Research Database (Denmark)

    Röd, Sara Katrine Solhøj; Hansen, Flemming; Leipold, Frank

    Sliced ready-to-eat (RTE) meat products are susceptible to growth of the foodborne pathogenic bacterium, Listeria monocytogenes. Cold atmospheric pressure plasma (CAPP) may be applicable for surface decontamination in sealed bags thus avoiding recontamination. Plasmas (Fig. 1), created in neutral...

  1. Atmospheric pressure photoionization for enhanced compatibility in on-line micellar electrokinetic chromatography-mass spectrometry

    NARCIS (Netherlands)

    Mol, Roelof; De Jong, Gerhardus J.; Somsen, Govert W.

    2005-01-01

    Atmospheric pressure photoionization (APPI) is presented as a novel means for the combination of micellar electrokinetic chromatography (MEKC) and mass spectrometry (MS). The on-line coupling is achieved using an adapted sheath flow interface installed on an orthogonal APPI source. Acetone or

  2. High-throughput processes for industrially scalable deposition of zinc oxide at atmospheric pressure

    NARCIS (Netherlands)

    Illiberi, A.; Grob, F.; Kniknie, B.; Frijters, C.; Deelen, J. van; Poodt, P.; Beckers, E.H.A.; Bolt, P.J.

    2014-01-01

    ZnO films have been grown on a moving glass substrate by high temperature (480 0C) chemical vapour deposition (CVD) and low temperature (200 0C) plasma enhanced CVD (PE-CVD) process at atmospheric pressure. Deposition rates above 7 nm/s have been achieved for substrate speeds from 20 to 500 mm/min.

  3. Effect of Atmospheric Pressure Plasma Modification on Polyimide and Adhesive Joining with Titanium

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.; Ajeesh, G.; Ahmed, S.; Chakraborty, D.

    2015-01-01

    This investigation highlights the effect of surface modification on polyimide by atmospheric pressure plasma treatment with different exposure time. Surface modification of polymer by plasma treatment essentially creates physical and chemical changes such as cross-linking and formation of free

  4. Sterilization of packed matter by means of low temperature atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank

    2010-01-01

    Summary form only given. The decontamination of material in closed containers by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua, is ...

  5. Atmospheric pressure plasma surface modification of titanium for high temperature adhesive bonding

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.

    2011-01-01

    In this investigation surface treatment of titanium is carried out by plasma ion implantation under atmospheric pressure plasma in order to increase the adhesive bond strength. Prior to the plasma treatment, titanium surfaces were mechanically treated by sand blasting. It is observed that the

  6. Ultrasound enhanced 50 Hz plasma treatment of glass-fiber-reinforced polyester at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Norrman, Kion; Singh, Shailendra Vikram

    2013-01-01

    Glass-fiber-reinforced polyester (GFRP) plates are treated using a 50Hz dielectric barrier discharge at a peak-to-peak voltage of 30 kV in helium at atmospheric pressure with and without ultrasonic irradiation to study adhesion improvement. The ultrasonic waves at the fundamental frequency of aro...

  7. Atmospheric pressure chemical vapor deposition of ZnO: Process modeling and experiments

    NARCIS (Netherlands)

    Deelen, J. van; Illiberi, A.; Kniknie, B.; Beckers, E.H.A.; Simons, P.J.P.M.; Lankhorst, A.

    2014-01-01

    The deposition of zinc oxide has been performed by atmospheric pressure chemical vapor deposition and trends in growth rates are compared with the literature. Diethylzinc and tertiary butanol were used as the primary reactants and deposition rates above 800 nm/min were obtained. The reaction

  8. Atmospheric pressure chemical vapor deposition of ZnO: Process modeling and experiments

    NARCIS (Netherlands)

    Deelen, J. van; Illiberi, A.; Kniknie, B.; Beckers, E.H.A.; Simons, P.J.P.M.; Lankhorst, A.

    2013-01-01

    The deposition of zinc oxide has been performed by atmospheric pressure chemical vapor deposition and trends in growth rates are compared with the literature. Diethylzinc and tertiary butanol were used as the primary reactants and deposition rates above 800 nm/minwere obtained. The reaction

  9. Electron confinement and heating in microwave-sustained argon microplasmas

    Science.gov (United States)

    Hoskinson, Alan R.; Gregório, José; Parsons, Stephen; Hopwood, Jeffrey

    2015-04-01

    We systematically measure and model the behavior of argon microplasmas sustained by a broad range of microwave frequencies. The plasma behavior exhibits two distinct regimes. Up to a transition frequency of approximately 4 GHz, the electron density, directly measured by Stark broadening, increases rapidly with rising frequency. Above the transition frequency, the density remains approximately constant near 5 × 1020 m-3. The electrode voltage falls with rising frequency across both regimes, reaching approximately 5 V at the highest tested frequency. A fluid model of the plasma indicates that the falling electrode voltage reduces the electron temperature and significantly improves particle confinement, which in turn increases the plasma density. Particles are primarily lost to the electrodes at lower frequencies, but dissociative recombination becomes dominant as particle confinement improves. Recombination events produce excited argon atoms which are efficiently re-ionized, resulting in relatively constant ionization rates despite the falling electron temperature. The fast rates of recombination are the result of high densities of electrons and molecular ions in argon microplasmas.

  10. Relating landfill gas emissions to atmospheric pressure using numerical modeling and state-space analysis

    DEFF Research Database (Denmark)

    Poulsen, T.G.; Christophersen, Mette; Moldrup, P.

    2003-01-01

    Landfill gas (CO2 and CH4) concentrations and fluxes in soil adjacent to an old, unlined Danish municipal landfill measured over a 48-hour period during the passage of a low-pressure weather system were used to identify processes governing gas fluxes and concentrations. Two different approaches...... with rapidly decreasing atmospheric pressures resulting in emission of large amounts of CH4 during short periods of time. This effect, however, was less significant for the CO2 fluxes.......-water content, soil gas permeability, soil gas diffusion coefficients, and biological CH4 degradation rate upon landfill gas concentration and fluxes in the soil. Fluxes and concentrations were found to be most sensitive to variations in volumetric soil water content, atmospheric pressure variations and gas...

  11. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    Science.gov (United States)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  12. Weather forecasting by insects: modified sexual behaviour in response to atmospheric pressure changes.

    Science.gov (United States)

    Pellegrino, Ana Cristina; Peñaflor, Maria Fernanda Gomes Villalba; Nardi, Cristiane; Bezner-Kerr, Wayne; Guglielmo, Christopher G; Bento, José Maurício Simões; McNeil, Jeremy N

    2013-01-01

    Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We

  13. Weather forecasting by insects: modified sexual behaviour in response to atmospheric pressure changes.

    Directory of Open Access Journals (Sweden)

    Ana Cristina Pellegrino

    Full Text Available Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera, the true armyworm moth, Pseudaletia unipuncta (Lepidoptera and the potato aphid, Macrosiphum euphorbiae (Hemiptera, when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating

  14. A two-dimensional array of microplasmas generated using microwave resonators

    Science.gov (United States)

    Hoskinson, Alan R.; Hopwood, Jeffrey

    2012-10-01

    We present a novel array of microplasma sources consisting of microwave resonators arranged in a two-dimensional grid. When microwave power is supplied to one of these resonators, it is shared among the entire array. Microplasmas are generated between the end of each resonator and a ground plane resulting in a ‘sheet’ of plasma. The source design, results of electromagnetic modeling, and initial experimental results are described.

  15. Pulmonary and heart diseases with inhalation of atmospheric pressure plasma flow

    Science.gov (United States)

    Hirata, Takamichi; Murata, Shigeru; Kishimoto, Takumi; Tsutsui, Chihiro; Kondo, Akane; Mori, Akira

    2012-10-01

    We examined blood pressure in the abdominal aorta of mini pig under plasma inhalation of atmospheric pressure plasma flow. The coaxial atmospheric pressure plasma source has a tungsten wire inside a glass capillary, that is surrounded by a grounded tubular electrode. Plasma was generated under the following conditions; applied voltage: 8 kVpp, frequency: 3 kHz, and helium (He) gas flow rate: 1 L/min. On the other hand, sphygmomanometry of a blood vessel proceeded using a device comprising a disposable force transducer, and a bedside monitor for simultaneous electrocardiography and signal pressure measurements. We directly measured Nitric oxide (NO) using a catheter-type NO sensor placed in the coronary sinus through an angiography catheter from the abdomen. Blood pressure decreased from 110/65 to 90/40 mm Hg in the animals in vivo under plasma inhalation. The NO concentration in the abdominal aorta like the blood pressure, reached a maximum value at about 40 s and then gradually decreased.

  16. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures: SBIR Phase I Final Report

    Science.gov (United States)

    Likhanskii, Alexandre

    2012-01-01

    This report is the final report of a SBIR Phase I project. It is identical to the final report submitted, after some proprietary information of administrative nature has been removed. The development of a numerical simulation tool for dielectric barrier discharge (DBD) plasma actuator is reported. The objectives of the project were to analyze and predict DBD operation at wide range of ambient gas pressures. It overcomes the limitations of traditional DBD codes which are limited to low-speed applications and have weak prediction capabilities. The software tool allows DBD actuator analysis and prediction for subsonic to hypersonic flow regime. The simulation tool is based on the VORPAL code developed by Tech-X Corporation. VORPAL's capability of modeling DBD plasma actuator at low pressures (0.1 to 10 torr) using kinetic plasma modeling approach, and at moderate to atmospheric pressures (1 to 10 atm) using hydrodynamic plasma modeling approach, were demonstrated. In addition, results of experiments with pulsed+bias DBD configuration that were performed for validation purposes are reported.

  17. Correlation between the season, temperature and atmospheric pressure with incidence and pathogenesis of acute appendicitis

    Directory of Open Access Journals (Sweden)

    Karanikolić Aleksandar

    2016-01-01

    Full Text Available Introduction. There is very little literature data on the correlation between the seasons, temperature and atmospheric pressure, and pathogenesis of acute appendicitis (AA. Objective. The aim of this research is to investigate the association between the seasons, changes in atmospheric temperature and pressure, and patients’ age and severity of the clinical form of AA in the city of Niš. Methods. This study included 395 patients diagnosed with AA, who, during the two-year period, from July 1st 2011 to June 30th 2013, were hospitalized and operated on at the Department of General Surgery, Clinical Center in Niš, Serbia. Results. The increased average daily values of barometric pressure by 1 millibar on the day when the event took place was associated (p < 0.05 with the decrease of total risk of the occurrence of appendicitis by 2.2% (0.2-4.1%. In all observed patients, each increase of the mean daily temperature by 1°C three days before the event took place (Lag 3 was associated (p < 0.05 with the increase of total risk of the occurrence of appendicitis by 1.3% (0.1-2.5%. Conclusion. According to the results of this research, we can conclude that patients’ sex, age and severity of the clinical form of AA are not in connection with the seasons, while there are certain connections between appendicitis occurrence and atmospheric temperature and pressure.

  18. The initial responses of hot liquid water released under low atmospheric pressures: Experimental insights

    Science.gov (United States)

    Bargery, Alistair Simon; Lane, Stephen J.; Barrett, Alexander; Wilson, Lionel; Gilbert, Jennie S.

    2010-11-01

    Experiments have been performed to simulate the shallow ascent and surface release of water and brines under low atmospheric pressure. Atmospheric pressure was treated as an independent variable and water temperature and vapor pressure were examined as a function of total pressure variation down to low pressures. The physical and thermal responses of water to reducing pressure were monitored with pressure transducers, temperature sensors and visible imaging. Data were obtained for pure water and for solutions with dissolved NaCl or CO 2. The experiments showed the pressure conditions under which the water remained liquid, underwent a rapid phase change to the gas state by boiling, and then solidified because of removal of latent heat. Liquid water is removed from phase equilibrium by decompression. Solid, liquid and gaseous water are present simultaneously, and not at the 611 Pa triple point, because dynamic interactions between the phases maintain unstable temperature gradients. After phase changes stop, the system reverts to equilibrium with its surroundings. Surface and shallow subsurface pressure conditions were simulated for Mars and the icy satellites of the outer Solar System. Freezing by evaporation in the absence of wind on Mars is shown to be unlikely for pure water at pressures greater than c. 670 Pa, and for saline solutions at pressures greater than c. 610 Pa. The physical nature of ice that forms depends on the salt content. Ice formed from saline water at pressures less than c. 610 Pa could be similar to terrestrial sea ice. Ice formed from pure water at pressures less than c. 100 Pa develops a low thermal conductivity and a 'honeycomb' structure created by sublimation. This ice could have a density as low as c. 450 kg m -3 and a thermal conductivity as low as 1.6 W m -1 K -1, and is highly reflective, more akin to snow than the clear ice from which it grew. The physical properties of ice formed from either pure or saline water at low pressures will

  19. Atmospheric pressure plasma jet's characterization and surface wettability driven by neon transformer

    Science.gov (United States)

    Elfa, R. R.; Nafarizal, N.; Ahmad, M. K.; Sahdan, M. Z.; Soon, C. F.

    2017-03-01

    Atmospheric pressure plasma driven by Neon transformer power supply argon is presented in this paper. Atmospheric pressure plasma system has attracted researcher interest over low pressure plasma as it provides a flexibility process, cost-efficient, portable device and vacuum-free device. Besides, another golden key of this system is the wide promising application in the field of work cover from industrial and engineering to medical. However, there are still numbers of fundamental investigation that are necessary such as device configuration, gas configuration and its effect. Dielectric barrier discharge which is also known as atmospheric pressure plasma discharge is created when there is gas ionization process occur which enhance the movement of atom and electron and provide energetic particles. These energetic particles can provide modification and cleaning property to the sample surface due to the bombardment of the high reactive ion and radicals to the sample surface. In order to develop atmospheric pressure plasma discharge, a high voltage and high frequency power supply is needed. In this work, we used a neon transformer power supply as the power supply. The flow of the Ar is feed into 10 mm cylinder quartz tube with different treatment time in order to investigate the effect of the plasma discharge. The analysis of each treatment time is presented by optical emission spectroscopy (OES) and water contact angle (WCA) measurement. The increase of gas treatment time shows increases intensity of reactive Ar and reduces the angle of water droplets in water contact angle. Treatment time of 20 s microslide glass surface shows that the plasma needle discharges have modified the sample surface from hydrophilic surface to superhydrophilic surface. Thus, this leads to another interesting application in reducing sample surface adhesion to optimize productivity in the industry of paintings, semiconductor and more.

  20. Could Nano-Structured Materials Enable the Improved Pressure Vessels for Deep Atmospheric Probes?

    Science.gov (United States)

    Srivastava, D.; Fuentes, A.; Bienstock, B.; Arnold, J. O.

    2005-01-01

    A viewgraph presentation on the use of Nano-Structured Materials to enable pressure vessel structures for deep atmospheric probes is shown. The topics include: 1) High Temperature/Pressure in Key X-Environments; 2) The Case for Use of Nano-Structured Materials Pressure Vessel Design; 3) Carbon based Nanomaterials; 4) Nanotube production & purification; 5) Nanomechanics of Carbon Nanotubes; 6) CNT-composites: Example (Polymer); 7) Effect of Loading sequence on Composite with 8% by volume; 8) Models for Particulate Reinforced Composites; 9) Fullerene/Ti Composite for High Strength-Insulating Layer; 10) Fullerene/Epoxy Composite for High Strength-Insulating Layer; 11) Models for Continuous Fiber Reinforced Composites; 12) Tensile Strength for Discontinuous Fiber Composite; 13) Ti + SWNT Composites: Thermal/Mechanical; 14) Ti + SWNT Composites: Tensile Strength; and 15) Nano-structured Shell for Pressure Vessels.

  1. High temperature gradient nanogap-Pirani micro-sensor with maximum sensitivity around atmospheric pressure

    Science.gov (United States)

    Ghouila-Houri, C.; Talbi, A.; Viard, R.; Moutaouekkil, M.; Elmazria, O.; Gallas, Q.; Garnier, E.; Merlen, A.; Pernod, P.

    2017-09-01

    This letter describes and discusses the design and testing of an efficient nanogap Pirani micro-sensor for pressure measurements in a wide range with a maximum sensitivity around atmospheric pressure. The structure combines a substrate-free heated wire and a mechanical support made of silicon oxide micro-bridges allowing both a constant nanoscale gap between the wire and the substrate and a 1 mm long and 3 μm wide wire. The high aspect ratio of the wire provides a uniform heating profile along the wire and contributes to low pressure detection. On the contrary, both the nanoscale gap and the short wire length between two micro-bridges contribute to shift the high limit of the pressure range. When tested between 10 kPa and 800 kPa, the sensor presents a wide measurement range, not fully reached by the experiments, with a maximum of sensitivity close to the atmospheric pressure and performances with up to 38%/dec sensitivity when operating in a constant temperature mode with an overheat of 20 °C.

  2. Black pepper powder microbiological quality improvement using DBD systems in atmospheric pressure

    Science.gov (United States)

    Grabowski, Maciej; Hołub, Marcin; Balcerak, Michał; Kalisiak, Stanisław; Dąbrowski, Waldemar

    2015-07-01

    Preliminary results are given regarding black pepper powder decontamination using dielectric barrier discharge (DBD) plasma in atmospheric pressure. Three different DBD reactor constructions were investigated, both packaged and unpackaged material was treated. Due to potential, industrial applications, in addition to microbiological results, water activity, loss of mass and the properties of packaging material, regarding barrier properties were investigated. Argon based treatment of packed pepper with DBD reactor configuration is proposed and satisfactory results are presented for treatment time of 5 min or less. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  3. Measurement and analysis for optical radiation of glow discharge plasma at atmospheric pressure

    Science.gov (United States)

    Ren, Qinglei; Lin, Qi

    2006-02-01

    The optical radiation measurement and analysis to the glow discharge plasma at atmospheric pressure have been done in the paper. The low temperature plasma due to atmospheric pressure glow discharge (APGD) in air has been produced on the planar surface of designed electrode plate. The optical radiation spectra of the plasma produced in two kinds of electrode plats with different power values loaded have been measured and sampled with the minitype grating spectrograph system. The acquired spectra data are processed averagely and analyzed. The results of analysis indicate that the optical characteristic of the APGD plasma is related to the loaded power and layout of the electrode plate. This shows that it is feasible to describe the characteristic parameters of APGD plasma qualitatively and control the strength of the APGD plasma quantitatively by the obtained relationship, which provides a convenient approach for utilizing APGD plasma effectively and also establishes some foundation to investigate APGD plasma further.

  4. Comparative study between chemical and atmospheric pressure plasma jet cleaning on glass substrate

    Science.gov (United States)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Fhong, Soon Chin; Sahdan, Mohd Zainizan; Nayan, Nafarizal

    2017-01-01

    The atmospheric pressure plasma jet with low frequency and argon as working gas is presented in this paper to demonstrate its application for glass substrate clean and modification. The glass substrate clean by atmospheric pressure plasma jet is an efficient method to replace other substrate clean method. A comparative analysis is done in this paper between substrate cleaned by chemical and plasma treatment methods. Water contact angle reading is taken for a different method of substrate clean and period of treatment. Under the plasma treatment, the sample shows low surface adhesion due to having the surface property of super hydrophilic surface 7.26°. This comparative analysis is necessary in the industrial application for cost production due to sufficient time and method of substrate clean.

  5. Atmospheric pressure plasma jets: an overview of devices and new directions

    Science.gov (United States)

    Winter, J.; Brandenburg, R.; Weltmann, K.-D.

    2015-12-01

    Atmospheric pressure plasma jets have a long history of more than 50 years. During this time their design and plasma generation mechanism has been developed and adapted to various fields of applications. This review aims at giving an overview of jet devices by starting with a brief history of their development. This is followed by an overview of commonly used terms and definitions as well as a survey of different classification schemes (e.g. geometry, excition frequency or specific energy input) described in literature. A selective update of new designs and novel research achievments on atmospheric pressure plasma jets published in 2012 or later shows the impressive variety and rapid development of the field. Finally, a brief outlook on the future trends and directions is given.

  6. Role of ambient dielectric in propagation of Ar atmospheric pressure nonequilibrium plasma jets

    Science.gov (United States)

    Song, Jian; Tang, Jingfeng; Wang, Youyin; Wei, Liqiu; Ren, Chunsheng; Yu, Daren

    2015-05-01

    A single-electrode atmospheric pressure nonequilibrium plasma jet surrounded with different ambient dielectrics is investigated driven by AC power supply. Another three ambient dielectrics, distilled water, ethanol, and carbon tetrachloride, are adopted to compare with air. By examining electrical and optical characteristics, it was found that the molecular polarity of ambient dielectrics had its significant effect on the propagation of atmospheric pressure nonequilibrium plasma jets. When the polarization of molecules was enhanced, the discharge current and the bullet velocity were also increased. For nonpolar dielectric of carbon tetrachloride, this was mainly resulted from the electron polarization in the built-in electric field. For polar dielectrics of ethanol and distilled water, in addition to the electron polarization, orientation polarization was the main cause for the further increase in discharge current and bullet velocity.

  7. Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus "Classic" Decontamination.

    Science.gov (United States)

    Hojnik, Nataša; Cvelbar, Uroš; Tavčar-Kalcher, Gabrijela; Walsh, James L; Križaj, Igor

    2017-04-28

    Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods.

  8. Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus “Classic” Decontamination

    Science.gov (United States)

    Hojnik, Nataša; Cvelbar, Uroš; Tavčar-Kalcher, Gabrijela; Walsh, James L.; Križaj, Igor

    2017-01-01

    Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods. PMID:28452957

  9. State of the art in medical applications using non-thermal atmospheric pressure plasma

    Science.gov (United States)

    Tanaka, Hiromasa; Ishikawa, Kenji; Mizuno, Masaaki; Toyokuni, Shinya; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Metelmann, Hans-Robert; Hori, Masaru

    2017-12-01

    Plasma medical science is a novel interdisciplinary field that combines studies on plasma science and medical science, with the anticipation that understanding the scientific principles governing plasma medical science will lead to innovations in the field. Non-thermal atmospheric pressure plasma has been used for medical treatments, such as for cancer, blood coagulation, and wound healing. The interactions that occur between plasma and cells/tissues have been analyzed extensively. Direct and indirect treatment of cells with plasma has broadened the applications of non-thermal atmospheric pressure plasma in medicine. Examples of indirect treatment include plasma-assisted immune-therapy and plasma-activated medium. Controlling intracellular redox balance may be key in plasma cancer treatment. Animal studies are required to test the effectiveness and safety of these treatments for future clinical applications.

  10. Properties of the acrylic acid polymers obtained by atmospheric pressure plasma polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Topala, Ionut [Plasma Physics Laboratory, Faculty of Physics, Al. I. Cuza University, 11 Carol I Boulevard, 700506 Iasi (Romania)], E-mail: itopala@plasma.uaic.ro; Dumitrascu, Nicoleta; Popa, Gheorghe [Plasma Physics Laboratory, Faculty of Physics, Al. I. Cuza University, 11 Carol I Boulevard, 700506 Iasi (Romania)

    2009-01-15

    Plasma polymers of acrylic acid were obtained using an atmospheric pressure discharge system. The plasma polymerization reactor uses a dielectric barrier discharge, with the polyethylene terephthalate dielectric acting as substrate for deposition. The plasma was characterized by specific electrical measurements, monitoring the applied voltage and the discharge current. Based on the spatially resolved optical emission spectroscopy, we analyzed the distribution of the excited species in the discharge gap, specific plasma temperatures (vibrational and gas temperatures) being calculated with the Boltzmann plot method. The properties of the plasma polymer films were investigated by contact angle measurements, infrared and UV-Vis spectroscopy, scanning electron microscopy. The films produced by plasma polymerization at atmospheric pressure showed a hydrophilic character, in correlation with the strong absorbance of OH groups in the FTIR spectrum. Moreover, the surface of the plasma polymers at micrometric scale is smooth and free of defects without particular features.

  11. ATMOSPHERIC PRESSURE AND ITS INFLUENCE ON TOURISTS AND TOURISM ACTIVITIES IN THE PRAHOVA CORRIDOR

    Directory of Open Access Journals (Sweden)

    HAVRIŞ LOREDANA-ELENA

    2014-03-01

    Full Text Available In the climate literature it is known that the atmospheric temperature directly and permanently acts on the all organisms and all geographical environment components, influencing the wellness of the weather sensitive persons and implicitly the wellness of tourists in this region. In the same time, its evolution is a good indicator in shaping the short and medium term meteorological forecast, considering that the region chosen for research is a very tripper one, especially during the winter season when the atmospheric pressure variation trend is much more pronounced. Within this framework, the present paper tries to develop a climatic diagnosis on the reference climate parameters (annual and monthly average pressure values, seasonal values, minimum and maximum absolute values and their emergence probability but also the non-periodic variability based on data recorded during 1961-2007 at Câmpina, Sinaia 1500, Predeal, Omu Peak and Braşov weather stations.

  12. Parameters of a supershort avalanche electron beam generated in atmospheric-pressure air

    Science.gov (United States)

    Tarasenko, V. F.

    2011-05-01

    Conditions under which the number of runaway electrons in atmospheric-pressure air reaches ˜5 × 1010 are determined. Recommendations for creating runaway electron accelerators are given. Methods for measuring the parameters of a supershort avalanche electron beam and X-ray pulses from gas-filled diodes, as well as the discharge current and gap voltage, are described. A technique for determining the instant of runaway electron generation with respect to the voltage pulse is proposed. It is shown that the reduction in the gap voltage and the decrease in the beam current coincide in time. The mechanism of intense electron beam generation in gas-filled diodes is analyzed. It is confirmed experimentally that, in optimal regimes, the number of electrons generated in atmospheric-pressure air with energies T > eU m , where U m is the maximum gap voltage, is relatively small.

  13. Effect of Atmospheric Pressure Plasma and Subsequent Enzymatic Treatment on Flax Fabrics

    Science.gov (United States)

    Zhong, Shaofeng; Yang, Bin; Ou, Qiongrong

    2015-09-01

    The objective is to investigate the effect of atmospheric pressure dielectric barrier discharge (APDBD) plasma and subsequent cellulase enzyme treatment on the properties of flax fabrics. The changes of surface morphology and structure, physico-mechanical properties, hydrophilicity, bending properties, whiteness, and dyeing properties of the treated substrate were investigated. The results indicated that atmospheric pressure dielectric barrier discharge plasma pre-treatment and subsequent cellulase enzyme treatment could diminish the hairiness of flax fabrics, endowing the flax fabrics with good bending properties, water uptake and fiber accessibility while keeping their good mechanical properties compared with those treated with cellulase enzyme alone. supported by the Science and Technology Project of the Education Department of Zhejiang Province, China (No. Y201432680) and the Professional Leaders Leading Project of the Education Department of Zhejiang Province, China (No. lj2013131), the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of the Education Department of Zhejiang Province, China (No. 1097802072012001)

  14. Charge dependence of the plasma travel length in atmospheric-pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yambe, Kiyoyuki; Konda, Kohmei; Masuda, Seiya [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)

    2016-06-15

    Plasma plume is generated using a quartz tube, helium gas, and foil electrode by applying AC high voltage under the atmosphere. The plasma plume is released into the atmosphere from inside of the quartz tube and is seen as the continuous movement of the plasma bullet. The travel length of plasma bullet is defined from plasma energy and force due to electric field. The drift velocity of plasma bullet has the upper limit under atmospheric-pressure because the drift velocity is determined from the balance between electric field and resistive force due to collisions between plasma and air. The plasma plume charge depends on the drift velocity. Consequently, in the laminar flow of helium gas flow state, the travel length of the plasma plume logarithmically depends on the plasma plume charge which changes with both the electric field and the resistive force.

  15. Glow plasma jet - experimental study of a transferred atmospheric pressure glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Guerra-Mutis, Marlon H [Mares Oil Ltd., Instituto Colombiano del Petroleo (ICP) - ECOPETROL (Colombia); U, Carlos V Pelaez [Laboratorio de Control Magnetico de Fluidos, Instituto Colombiano del Petroleo (ICP) - ECOPETROL (Colombia); H, Rafael Cabanzo [Laboratorio de Espectroscopia Atomico-Molecular (LEAM) - UIS (Colombia)

    2003-05-01

    In this paper we present the experimental study of a glow plasma jet (GPJ) obtained from a transferred atmospheric pressure glow discharge (APGD) operating at 60 Hz. The characterization of the emission spectra for both electrical discharges is presented and the electrical circuit features for APGD generation are discussed. The potentiality of GPJ as a source of active species for depletion of contaminants in liquid hydrocarbon fractions is also established.

  16. Oral bacterial inactivation using a novel low-temperature atmospheric-pressure plasma device

    Directory of Open Access Journals (Sweden)

    Ya-Ting Chang

    2016-03-01

    Conclusion: The novel low-temperature atmospheric-pressure device was capable of achieving effective sterilization of E. faecalis within a 2-minute interval. Further studies are needed to validate complete inactivation, refine the laboratory-made low-temperature plasma device, and develop a new plasma-jet device, which will be superior to traditional sterilization methods and can be used in root canal environment. This novel sterilization method can also be used as a clinical reference tool.

  17. Effect of nozzle profile on gas mixing in an atmospheric and low pressure DC plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Rahmane, M.; Soucy, G.; Boulos, M.I. [Univ. of Sherbrooke, Quebec (Canada); Henne, R. [Inst. for Technical Thermodynamics, Stuttgart (Germany)

    1994-12-31

    The study combines enthalpy probe and mass spectrometer measurements in a DC-plasma jet under atmospheric and low pressure conditions. Both, standard cylindrical and laval nozzle were used as anode profiles. A detailed description of the experimental technique is given together with preliminary results. These confirm the role by which enthalpy probe measurements can be used to bridge the gap in temperature range between emission spectroscopic techniques and standard thermocouple probing.

  18. Characterization of an atmospheric pressure air plasma source for polymer surface modification

    Science.gov (United States)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

    An atmospheric pressure air plasma source was generated through dielectric barrier discharge (DBD). It was used to modify polyethyleneterephthalate (PET) surfaces with very high throughput. An equivalent circuit model was used to calculate the peak average electron density. The emission spectrum from the plasma was taken and the main peaks in the spectrum were identified. The ozone density in the down plasma region was estimated by Absorption Spectroscopy. NSF and ARC-ODU

  19. Fundamental Studies of Transient, Atmospheric-Pressure, Small-Scale Plasmas

    Science.gov (United States)

    2017-01-23

    C. Jiang, R. Heller, J. Lane, and K. H. Schoenbach, " Ozone -free nitric oxide production using an atmospheric pressure surface discharge – a way to...Electrostatic modeling and energy-dependent studies showed that the direct and indirect electron-induced processes in the pulsed plasma jet are responsible for...Coupled sliding discharges : a scalable nonthermal plasma system utilizing positive and negative streamers on DISTRIBUTION A: Distribution

  20. REFERENCE ON THERMOPHYSICAL PROPERTIES: DENSITY AND VISCOSITY OF WATER FOR ATMOSPHERIC PRESSURE

    Directory of Open Access Journals (Sweden)

    Elin Yusibani

    2016-09-01

    Full Text Available A reference on thermophysical properties, density and viscosity, for water at atmospheric pressure has been developed in MS Excel (as a macros. Patterson’s density equations and Kestin’s viscosity equations have been chosen as a basic equation in the VBA programming as a user-defined function. These results have been compared with REFPROF as a wellknow standart reference

  1. Micro Raman investigation of graphene synthesized by atmospheric pressure CVD on copper foil from decane

    OpenAIRE

    Komissarov, I. V.; Kovalchuk, N. G.; Kolesov, E. A.; Tivanov, M. S.; Korolik, O. V.; Mazanik, A. V.; Shaman, Yu. P.; Basaev, A. S.; Labunov, V. A.; Prischepa, S. L.; Kargin, N. I.; Ryzhuk, R. V.; Shostachenko, S. A.

    2015-01-01

    In this article we present the results of micro-Raman studies of graphene grown on copper foil surface by atmospheric pressure CVD using decane as precursor, nitrogen as carrier gas with zero flow of hydrogen. Analysis of Raman spectroscopy data showed that film contains spots with single layer thick graphene. We observed significant blue shift of 2D and G bands positions for mono-atomically thick graphene on copper foil. Following literature we relate this shift to the strain induce...

  2. High quality graphene synthesized by atmospheric pressure CVD on copper foil

    OpenAIRE

    Trinsoutrot, Pierre; Rabot, Caroline; Vergnes, Hugues; Delamoreanu, Alexandru; Zenasni, Aziz; Caussat, Brigitte

    2013-01-01

    International audience; Graphene was synthesized at 1000 °C by Atmospheric Pressure Chemical Vapor Deposition on copper foil from methane diluted in argon and hydrogen. The influence of the main synthesis parameters was studied on 2 × 2 cm2 foils in order to obtain continuous monolayer graphenewithout crystalline defect. The uniformity, crystal quality and number of layers of graphenewere analyzed by Raman spectroscopy and Scanning Electronic Microscopy. First, an increase of the annealing pr...

  3. Performance characteristics of large aperture, ten-cell atmospheric pressure isobutane Cherenkov counters

    Science.gov (United States)

    Hylen, J.; Ming Ma, Z.; Jawahery, A.; Maruyama, T.; Milburn, R. H.

    1981-06-01

    Two large-aperture, 10-cell atmospheric-pressure isobutane Cherenkov counters were designed and constructed for a SLAC streamer-chamber experiment. The rejection efficiencies for a 9 GeV/ cπ- were measured to be 99.84% ⋍ 0.006% and 99.717% ± 0.008% for the two counters. The design details and performance characteristics are discussed.

  4. Radiative ion-ion neutralization: a new gas-phase atmospheric pressure ion transduction mechanism.

    Science.gov (United States)

    Davis, Eric J; Siems, William F; Hill, Herbert H

    2012-06-05

    All atmospheric pressure ion detectors, including photo ionization detectors, flame ionization detectors, electron capture detectors, and ion mobility spectrometers, utilize Faraday plate designs in which ionic charge is collected and amplified. The sensitivity of these Faraday plate ion detectors are limited by thermal (Johnson) noise in the associated electronics. Thus approximately 10(6) ions per second are required for a minimal detection. This is not the case for ion detection under vacuum conditions where secondary electron multipliers (SEMs) can be used. SEMs produce a cascade of approximately 10(6) electrons per ion impinging on the conversion dynode. Similarly, photomultiplier tubes (PMTs) can generate approximately 10(6) electrons per photon. Unlike SEMs, however, PMTs are evacuated and sealed so that they are commonly used under atmospheric pressure conditions. This paper describes an atmospheric pressure ion detector based on coupling a PMT with light emitted from ion-ion neutralization reactions. The normal Faraday plate collector electrode was replaced with an electrode "needle" used to concentrate the anions as they were drawn to the tip of the needle by a strong focusing electric field. Light was emitted near the surface of the electrode when analyte ions were neutralized with cations produced from the anode. Although radiative-ion-ion recombination has been previously reported, this is the first time ions from separate ionization sources have been combined to produce light. The light from this radiative-ion-ion-neutralization (RIIN) was detected using a photon multiplier such that an ion mobility spectrum was obtained by monitoring the light emitted from mobility separated ions. An IMS spectrum of nitroglycerin (NG) was obtained utilizing RIIN for tranducing the mobility separated ions into an analytical signal. The implications of this novel ion transduction method are the potential for counting ions at atmospheric pressure and for obtaining ion

  5. Atmospheric-pressure dielectric barrier discharge (DBD) in air : plasma characterisation for skin therapy

    OpenAIRE

    Rajasekaran, Priyadarshini

    2011-01-01

    A pulsed atmospheric-pressure dielectric barrier discharge (DBD) device operating in air is investigated for medical applications such as for skin disinfection and promotion of wound healing. The device ignites plasma on objects of high capacitance such as the human body and with grounded electrodes. Plasma parameters such as electron density and electron distribution function are determined. Plasma chemical kinetics is simulated and the production of biologically-useful molecules...

  6. Cleaning of niobium surface by plasma of diffuse discharge at atmospheric pressure

    Science.gov (United States)

    Tarasenko, V. F.; Erofeev, M. V.; Shulepov, M. A.; Ripenko, V. S.

    2017-07-01

    Elements composition of niobium surface before and after plasma treatment by runaway electron preionized diffuse discharge was investigated in atmospheric pressure nitrogen flow by means of an Auger electron spectroscopy. Surface characterizations obtained from Auger spectra show that plasma treatment by diffuse discharge after exposure of 120000 pulses provides ultrafine surface cleaning from carbon contamination. Moreover, the surface free energy of the treated specimens increased up to 3 times, that improve its adhesion property.

  7. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Kartick K; Jassal, Manjeet; Agrawal, Ashwini K, E-mail: ashwini@smita-iitd.co, E-mail: manjeet.jassal@smita-iitd.co [Smart and Innovative Textile Materials Group (SMITA), Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2010-02-01

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 {mu}l took around 250 s to get absorbed in the treated sample compared to < 1 s in the untreated samples. The plasma modified samples showed water contact angle of around 134{sup 0}. Both top and bottom sides of the fabric showed similar hydrophobic results in terms of water absorbency and contact angle. The results may be attributed to chemical reaction of butadiene with the cellulosic textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under <100 nm. The results showed that atmospheric pressure plasma can be successfully used for carrying out reaction of 1,3-butadiene with cellulosic textile substrates for producing hydrophobic surface finish.

  8. Micro-Biocidal Activity of Yeast Cells by Needle Plasma Irradiation at Atmospheric Pressure

    Science.gov (United States)

    Kurumi, Satoshi; Takahashi, Hideyuki; Taima, Tomohito; Suzuki, Kaoru; Hirose, Hideharu; Masutani, Shigeyuki

    In this study, we report on the biocidal activity technique by needle helium plasma irradiation at atmospheric pressure using borosilicate capillary nozzle to apply for the oral surgery. The diameter of needle plasma was less than 50 µm, and temperature of plasma irradiated area was less than body temperature. Needle plasma showed emission due to OH and O radical. Raman spectra and methylene blue stain showed yeast cells were inactivated by needle plasma irradiation.

  9. Adhesion improvement of fibres by continuous plasma treatment at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Sørensen, Bent F.

    2013-01-01

    Carbon fibres and ultra-high-molecular-weight polyethylene (UHMWPE) fibres were continuously treated by a dielectric barrier discharge plasma at atmospheric pressure for adhesion improvement with epoxy resins. The plasma treatment improved wettability, increased the oxygen containing polar...... functional groups at the surface, and subsequently improved adhesion to the epoxy and fracture resistance of epoxy composites. Hansen solubility parameters (HSP), quantitatively describing physical interactions among molecules, were measured for the UHMWPE fibre surfaces. The result identifies two distinct...

  10. Using dimers to measure biosignatures and atmospheric pressure for terrestrial exoplanets.

    Science.gov (United States)

    Misra, Amit; Meadows, Victoria; Claire, Mark; Crisp, Dave

    2014-02-01

    We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 μm dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bar and for O2 volume mixing ratios above 50% of Earth's present-day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 μm and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We also performed detectability studies for JWST transit transmission spectroscopy and found that the 1.06 and 1.27 μm dimer features could be detectable (SNR>3) for an Earth analogue orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis. We calculated the required signal-to-noise ratios to detect and characterize O2 monomer and dimer features in direct imaging-reflected spectra and found that signal-to-noise ratios greater than 10 at a spectral resolving power of R=100 would be required.

  11. Zero voltage switching driver and flyback transformer for generation of atmospheric pressure plasma jet

    Science.gov (United States)

    Zin, Rosnah Mohd; Soon, Chin Fhong; Sani, Mohd Zuhri Ab; Rizon, Elfa Rizan; Tee, Kian Sek; Ahmad, Mohd Khairul; Ahmad, Nabihah@Nornabihah; Jubadi, Warsuzarina Mat; Nayan, Nafarizal

    2017-09-01

    There are increasing interests in the application of cold atmospheric plasma device for the application in surface science and medical field. Numerous studies focused on the effects of plasma emission onto living organisms. This report presents the application of a power driver circuit for induction of cold atmospheric plasma (CAP). The system consists of a resonant inverter of Zero Voltage Switching (ZVS) circuit powered by a 12Vdc input voltage which is coupled to a flyback transformer in generation of high voltage up to 24.5 kV. The output voltage from the ZVS driver and flyback transformer to the plasma torch (quartz tube) was determined using Falstad circuit simulation. The simulation on the waveforms generated from the ZVS circuit correlated well with the actual voltage measurement at the output of the ZVS circuit. The peak voltage dropped across a parallel capacitor coupled to the flyback transformer is approximately 36 V. The atmospheric pressure plasma jet (APPJ) purged with Argon gas at a flow rate of 50 l/min was exposed to a leaf for 5 seconds. This created pin holes in the exposed area of the leaf indicating high temperature was induced at the focused spot of the plasma. An atmospheric pressure plasma jet (APPJ) system has been developed for with potential application in destructive medicine.

  12. Atmospheric pressure MALDI for the noninvasive characterization of carbonaceous ink from Renaissance documents.

    Science.gov (United States)

    Grasso, Giuseppe; Calcagno, Marzia; Rapisarda, Alessandro; D'Agata, Roberta; Spoto, Giuseppe

    2017-06-01

    The analytical methods that are usually applied to determine the compositions of inks from ancient manuscripts usually focus on inorganic components, as in the case of iron gall ink. In this work, we describe the use of atmospheric pressure/matrix-assisted laser desorption ionization-mass spectrometry (AP/MALDI-MS) as a spatially resolved analytical technique for the study of the organic carbonaceous components of inks used in handwritten parts of ancient books for the first time. Large polycyclic aromatic hydrocarbons (L-PAH) were identified in situ in the ink of XVII century handwritten documents. We prove that it is possible to apply MALDI-MS as a suitable microdestructive diagnostic tool for analyzing samples in air at atmospheric pressure, thus simplifying investigations of the organic components of artistic and archaeological objects. The interpretation of the experimental MS results was supported by independent Raman spectroscopic investigations. Graphical abstract Atmospheric pressure/MALDI mass spectrometry detects in situ polycyclic aromatic hydrocarbons in the carbonaceous ink of XVII century manuscripts.

  13. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Ishaq, M., E-mail: ishaqmusarat@gmail.com [Peter MacCallum Cancer Centre, East Melbourne, VIC 3002 (Australia); Comonwealth Scientific and Industrial Research Organization, Sydney, New South Wales (Australia); Bazaka, K. [Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Ostrikov, K. [Comonwealth Scientific and Industrial Research Organization, Sydney, New South Wales (Australia); Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia)

    2015-12-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown as a promising tool for cancer treatment. The mechanism of the plasma action is attributed to generation of reactive oxygen and nitrogen species, electric fields, charges, and photons. The relative importance of different modes of action of atmospheric-pressure plasmas depends on the process parameters and specific treatment objects. Hence, an in-depth understanding of biological mechanisms that underpin plasma-induced death in cancer cells is required to optimise plasma processing conditions. Here, the intracellular factors involved in the observed anti-cancer activity in melanoma Mel007 cells are studied, focusing on the effect of the plasma treatment dose on the expression of tumour suppressor protein TP73. Over-expression of TP73 causes cell growth arrest and/or apoptosis, and hence can potentially be targeted to enhance killing efficacy and selectivity of the plasma treatment. It is shown that the plasma treatment induces dose-dependent up-regulation of TP73 gene expression, resulting in significantly elevated levels of TP73 RNA and protein in plasma-treated melanoma cells. Silencing of TP73 expression by means of RNA interference inhibited the anticancer effects of the plasma, similar to the effect of caspase inhibitor z-VAD or ROS scavenger N-acetyl cysteine. These results confirm the role of TP73 protein in dose-dependent regulation of anticancer activity of atmospheric-pressure plasmas.

  14. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer.

    Science.gov (United States)

    Babij, Michał; Kowalski, Zbigniew W; Nitsch, Karol; Silberring, Jerzy; Gotszalk, Teodor

    2014-05-01

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet.

  15. Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

    Science.gov (United States)

    Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

    2016-11-14

    We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

  16. Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

    Science.gov (United States)

    Cao, Yingguang; Yang, Ping; Lu, Xinpei; Xiong, Zilan; Ye, Tao; Xiong, Qing; Sun, Ziyong

    2011-02-01

    Enterococcus faecalis (E. faecalis) is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofilm under different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus (S. aureus) was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively (P < 0.05). The diameter was increased with prolongation of the treatment duration. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm (P < 0.01). The transmission electron microscopy revealed that the ultrastructural changes cytoderm of E. faecalis were observed after treatment for 2 min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontic microbial treatment.

  17. Development of superhydrophobic surface on glass substrate by multi-step atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Han, Duksun [Department of Applied Plasma Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of); Moon, Se Youn, E-mail: symoon@jbnu.ac.kr [Department of Applied Plasma Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of); Department of Quantum system Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of)

    2015-07-31

    Superhydrophobic surface was prepared on a glass by helium based CH{sub 4} and C{sub 4}F{sub 8} atmospheric pressure plasmas, and its water wettability was investigated by a water droplet contact angle method. The water droplet spread over on the untreated glasses that showed the initial hydrophilic property of the glass surface. Then, the static contact angles became about 85° and 98° after a single step CH{sub 4} plasma treatment and a single step C{sub 4}F{sub 8} plasma treatment, respectively. The contact angle was remarkably increased to 152°, indicating a superhydrophobic property, after a sequential multi-step CH{sub 4} and C{sub 4}F{sub 8} plasma treatment. From the X-ray photoelectron spectroscopy and the field emission scanning electron microscope measurements, it was found that the physical morphologies and the chemical compositions were depending on the substrate materials, which were important factors for the superhydrophobicity. - Highlights: • Development of rapid and simple method for superhydrophobic surface • Effects of atmospheric pressure plasma for superhydrophobic surface preparation • Observation of chemical and physical surface modification by atmospheric pressure plasma • Effects of substrate properties for plasma–surface interaction.

  18. A novel APPI-MS setup for in situ degradation product studies of atmospherically relevant compounds: capillary atmospheric pressure photo ionization (cAPPI).

    Science.gov (United States)

    Kersten, Hendrik; Derpmann, Valerie; Barnes, Ian; Brockmann, Klaus J; O'Brien, Rob; Benter, Thorsten

    2011-11-01

    We report on the development of a novel atmospheric pressure photoionization setup and its applicability for in situ degradation product studies of atmospherically relevant compounds. A custom miniature spark discharge lamp was embedded into an ion transfer capillary, which separates the atmospheric pressure from the low pressure region in the first differential pumping stage of a conventional atmospheric pressure ionization mass spectrometer. The lamp operates with a continuous argon flow and produces intense light emissions in the VUV. The custom lamp is operated windowless and efficiently illuminates the sample flow through the transfer capillary on an area smaller than 1 mm(2). Limits of detection in the lower ppbV range, a temporal resolution of milliseconds in the positive as well as the quasi simultaneously operating negative ion mode, and a significant reduction of ion transformation processes render this system applicable to real time studies of rapidly changing chemical systems. The method termed capillary atmospheric pressure photo ionization (cAPPI) is characterized with respect to the lamp emission properties as a function of the operating conditions, temporal response, and its applicability for in situ degradation product studies of atmospherically relevant compounds, respectively.

  19. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    CERN Document Server

    Makarieva, A M; Sheil, D; Nobre, A D; Li, B -L

    2010-01-01

    Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from the fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 deg C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the...

  20. ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

    Directory of Open Access Journals (Sweden)

    Peter Pikna

    2014-10-01

    Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

  1. THE HABITABLE ZONE OF EARTH-LIKE PLANETS WITH DIFFERENT LEVELS OF ATMOSPHERIC PRESSURE

    Energy Technology Data Exchange (ETDEWEB)

    Vladilo, Giovanni; Murante, Giuseppe; Silva, Laura [INAF-Trieste Astronomical Observatory, Trieste (Italy); Provenzale, Antonello [Institute of Atmospheric Sciences and Climate-CNR, Torino (Italy); Ferri, Gaia; Ragazzini, Gregorio, E-mail: vladilo@oats.inaf.it [Department of Physics, University of Trieste, Trieste (Italy)

    2013-04-10

    As a contribution to the study of the habitability of extrasolar planets, we implemented a one-dimensional energy balance model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p = 1/3 to 3 bar. At low pressure, the habitability is low and varies with a; at high pressure, the habitability is high and relatively constant inside the HZ. We interpret these results in terms of the pressure dependence of the greenhouse effect, the efficiency of horizontal heat transport, and the extent of the liquid water temperature range. Within the limits discussed in the paper, the results can be extended to planets in eccentric orbits around non-solar-type stars. The main characteristics of the pressure-dependent HZ are modestly affected by variations of planetary properties, particularly at high pressure.

  2. An improved film evaporation correlation for saline water at sub-atmospheric pressures

    KAUST Repository

    Shahzada, Muhammad Wakil

    2011-10-03

    This paper presents an investigation of heat transfer correlation in a falling-film evaporator working with saline water at sub-atmospheric pressures. The experiments are conducted at different salinity levels ranging from 15000 to 90000 ppm, and the pressures were maintained between 0.92 to 2.81 kPa (corresponds to saturation temperatures of 5.9 – 23 0C). The effect of salinity, saturation pressures and chilled water temperatures on the heat transfer coefficient are accounted in the modified film evaporation correlations. The results are fitted to the Han & Fletcher\\'s and Chun & Seban\\'s falling-film correlations which are used in desalination industry. We modify the said correlations by adding salinity and saturation temperature corrections with respective indices to give a better agreement to our measured data.

  3. An improved film evaporation correlation for saline water at sub-atmospheric pressures

    Science.gov (United States)

    Shahzada, Muhammad Wakil; Ng, Kim Choon; Thu, Kyaw; Myat, Aung; Gee, Chun Won

    2012-06-01

    This paper presents an investigation of heat transfer correlation in a falling-film evaporator working with saline water at sub-atmospheric pressures. The experiments are conducted at different salinity levels ranging from 15000 to 90000 ppm, and the pressures were maintained between 0.92 to 2.81 kPa (corresponds to saturation temperatures of 5.9 - 23 0C). The effect of salinity, saturation pressures and chilled water temperatures on the heat transfer coefficient are accounted in the modified film evaporation correlations. The results are fitted to the Han & Fletcher's and Chun & Seban's falling-film correlations which are used in desalination industry. We modify the said correlations by adding salinity and saturation temperature corrections with respective indices to give a better agreement to our measured data.

  4. Meteorology in ruptured abdominal aortic aneurysm: an institutional study and a meta-analysis of published studies reporting atmospheric pressure.

    Science.gov (United States)

    Takagi, H; Watanabe, T; Mizuno, Y; Kawai, N; Umemoto, T

    2014-12-01

    The aim of this paper was to determine whether weather factors including atmospheric pressure are associated with the occurrence of ruptured abdominal aortic aneurysm (RAAA). We investigated our institutional experiences of RAAA in more than 150 patients during 8 years. Further, we performed a meta-analysis of published studies reporting the influence of atmospheric pressure on RAAA. We retrospectively evaluated 152 patients who underwent surgery for RAAA (including ruptured iliac arterial aneurysm) at our institute between 1 January 2006 and 31 December 2013. Daily regional meteorological data (in the nearest weather station located 3.5 km from the hospital) were obtained online from Japan Meteorological Agency. To identify comparative studies of mean atmospheric pressure on the day with RAAA versus that on the day without RAAA, MEDLINE and EMBASE were searched through January 2014 using Web-based search engines (PubMed and OVID). Mean sea level atmospheric pressure, delta mean atmospheric pressure (difference between mean sea level atmospheric pressure on the day and that on the previous day), and sunshine duration on the day with RAAA were significantly lower than those on the day without RAAA: 1012.43±7.44 versus 1013.71±6.49 hPa, P=0.039, -1.18±5.15 versus 0.05±5.62 hPa, P=0.005; and 4.76±3.76 versus 5.47±3.88 h, P=0.026; respectively. A pooled analysis of 8 studies (including our institutional study) demonstrated that mean atmospheric pressure on the day with RAAA was significantly lower than that on the day without RAAA: standardized mean difference, -0.09; 95% confidence interval, -0.14 to -0.04; P=0.0009. Atmospheric pressure on the day with RAAA appears lower than that on the day without RAAA. Atmospheric pressure may be associated with the occurrence of RAAA.

  5. Blow-out of nonpremixed turbulent jet flames at sub-atmospheric pressures

    KAUST Repository

    Wang, Qiang

    2016-12-09

    Blow-out limits of nonpremixed turbulent jet flames in quiescent air at sub-atmospheric pressures (50–100 kPa) were studied experimentally using propane fuel with nozzle diameters ranging 0.8–4 mm. Results showed that the fuel jet velocity at blow-out limit increased with increasing ambient pressure and nozzle diameter. A Damköhler (Da) number based model was adopted, defined as the ratio of characteristic mixing time and characteristic reaction time, to include the effect of pressure considering the variations in laminar burning velocity and thermal diffusivity with pressure. The critical lift-off height at blow-out, representing a characteristic length scale for mixing, had a linear relationship with the theoretically predicted stoichiometric location along the jet axis, which had a weak dependence on ambient pressure. The characteristic mixing time (critical lift-off height divided by jet velocity) adjusted to the characteristic reaction time such that the critical Damköhler at blow-out conditions maintained a constant value when varying the ambient pressure.

  6. Temperature diagnostics of a non-thermal plasma jet at atmospheric pressure

    Science.gov (United States)

    Schäfer, Jan

    2013-09-01

    The study reflects the concept of the temperature as a physical quantity resulting from the second thermodynamic law. The reliability of different approaches of the temperature diagnostics of open non-equilibrium systems is discussed using examples of low temperature atmospheric pressure discharges. The focus of this work is a miniaturized non-thermal atmospheric pressure plasma jet for local surface treatment at ambient atmosphere. The micro-discharge is driven with a capacitively coupled radio frequency electric field at 27.12 MHz and fed with argon at rates of about 1 slm through the capillary with an inner diameter of 4 mm. The discharge consists of several contracted filaments with diameter around 300 μm which are rotating azimuthally in the capillary in a self-organized manner. While the measured temperatures of the filament core exceed 700 K, the heat impact on a target below the plasma jet remains limited leading to target temperatures below 400 K. Different kinds of temperatures and energy transport processes are proposed and experimentally investigated. Nevertheless, a reliable and detailed temperature diagnostics is a challenge. We report on a novel diagnostics approach for the spatially and temporally resolved measurement of the gas temperature based on the optical properties of the plasma. Laser Schlieren Deflectometry is adapted to explore temperature profiles of filaments and their behaviour. In parallel, the method demonstrates a fundamental Fermat's principle of minimal energy. Information acquired with this method plays an important role for the optimization of local thin film deposition and surface functionalization by means of the atmospheric pressure plasma jet. The work was supported in part by the Deutsche Forschungsgemeinschaft within SFB-TR 24.

  7. Production of stable, non-thermal atmospheric pressure rf capacitive plasmas using gases other than helium or neon

    Science.gov (United States)

    Park, Jaeyoung; Henins, Ivars

    2005-06-21

    The present invention enables the production of stable, steady state, non-thermal atmospheric pressure rf capacitive .alpha.-mode plasmas using gases other than helium and neon. In particular, the current invention generates and maintains stable, steady-state, non-thermal atmospheric pressure rf .alpha.-mode plasmas using pure argon or argon with reactive gas mixtures, pure oxygen or air. By replacing rare and expensive helium with more readily available gases, this invention makes it more economical to use atmospheric pressure rf .alpha.-mode plasmas for various materials processing applications.

  8. Electron density measurement of non-equilibrium atmospheric pressure plasma using dispersion interferometer

    Science.gov (United States)

    Yoshimura, Shinji; Kasahara, Hiroshi; Akiyama, Tsuyoshi

    2017-10-01

    Medical applications of non-equilibrium atmospheric plasmas have recently been attracting a great deal of attention, where many types of plasma sources have been developed to meet the purposes. For example, plasma-activated medium (PAM), which is now being studied for cancer treatment, has been produced by irradiating non-equilibrium atmospheric pressure plasma with ultrahigh electron density to a culture medium. Meanwhile, in order to measure electron density in magnetic confinement plasmas, a CO2 laser dispersion interferometer has been developed and installed on the Large Helical Device (LHD) at the National Institute for Fusion Science, Japan. The dispersion interferometer has advantages that the measurement is insensitive to mechanical vibrations and changes in neutral gas density. Taking advantage of these properties, we applied the dispersion interferometer to electron density diagnostics of atmospheric pressure plasmas produced by the NU-Global HUMAP-WSAP-50 device, which is used for producing PAM. This study was supported by the Grant of Joint Research by the National Institutes of Natural Sciences (NINS).

  9. Etching of polymers, proteins and bacterial spores by atmospheric pressure DBD plasma in air

    Science.gov (United States)

    Kuzminova, A.; Kretková, T.; Kylián, O.; Hanuš, J.; Khalakhan, I.; Prukner, V.; Doležalová, E.; Šimek, M.; Biederman, H.

    2017-04-01

    Many studies proved that non-equilibrium discharges generated at atmospheric pressure are highly effective for the bio-decontamination of surfaces of various materials. One of the key processes that leads to a desired result is plasma etching and thus the evaluation of etching rates of organic materials is of high importance. However, the comparison of reported results is rather difficult if impossible as different authors use diverse sources of atmospheric plasma that are operated at significantly different operational parameters. Therefore, we report here on the systematic study of the etching of nine different common polymers that mimic the different structures of more complicated biological systems, bovine serum albumin (BSA) selected as the model protein and spores of Bacillus subtilis taken as a representative of highly resistant micro-organisms. The treatment of these materials was performed by means of atmospheric pressure dielectric barrier discharge (DBD) sustained in open air at constant conditions. All tested polymers, BSA and spores, were readily etched by DBD plasma. However, the measured etching rates were found to be dependent on the chemical structure of treated materials, namely on the presence of oxygen in the structure of polymers.

  10. Diffuse plasma treatment of polyamide 66 fabric in atmospheric pressure air

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lee, E-mail: leeli@mail.hust.edu.cn; Peng, Ming-yang; Teng, Yun; Gao, Guozhen

    2016-01-30

    Graphical abstract: - Highlights: • A cylindrical-electrode nanosecond-pulse diffuse-discharge reactor is presented. • Large-scale non-thermal plasmas were generated steadily in atmospheric air. • Treated PA66 fabric is etched with oxygen-containing group increases. • The hydrophily of treated PA66 fabric improves effectively. • Extending the treatment time is a method to reduce the treatment frequency. - Abstract: The polyamide 66 (PA66) fabrics are hard to be colored or glued in industrial production due to the poor hydrophily. Diffuse plasma is a kind of non-thermal plasma generated at atmospheric pressure in air. This paper proposes that large-scale diffuse plasma generated between wire electrodes can be employed for improving the hydrophily of PA66 fabrics. A repetitive nanosecond-pulse diffuse-discharge reactor using a cylindrical wire electrode configuration is presented, which can generate large-scale non-thermal plasmas steadily at atmospheric pressure without any barrier dielectric. Then the reactor is used to treat PA66 fabrics in different discharge conditions. The hydrophilicity property of modified PA66 is measured by wicking test method. The modified PA66 is also analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to prove the surface changes in physical microstructure and chemical functional groups, respectively. What's more, the effects of treatment time and treatment frequency on surface modification are investigated and discussed.

  11. Capillary-tube-based micro-plasma system for disinfecting dental biofilm.

    Science.gov (United States)

    Huang, Wen-Ke; Weng, Chih-Chiang; Liao, Jiunn-Der; Wang, Yi-Cheng; Chuang, Shu-Fen

    2013-05-01

    A low-temperature low-energy capillary-tube-based argon micro-plasma system was applied to disinfect Streptococcus mutans-containing biofilm. The micro-plasma system uses a hollow inner electrode that is ignited by a radio-frequency power supply with a matching network. The energy content was analyzed using optical emission spectroscopy. The micro-plasma-induced effect on a biofilm cultured for 24 or 48 h with a working distance of ≈3 mm at low temperature was evaluated. The morphologies of the treated live/dead bacteria and the produced polysaccharides after micro-plasma treatment were examined. Scanning electron microscopy images and staining results show that most of the S. mutans on the treated biofilm were acutely damaged within a micro-plasma treatment time of 300 s. The number of living bacteria underneath the treated biofilm greatly decreased with treatment time. The proposed micro-plasma system can thus disinfect S. mutans on/in biofilms.

  12. Growth of carbon nanowalls at atmospheric pressure for one-step gas sensor fabrication

    Directory of Open Access Journals (Sweden)

    Zhu Yanwu

    2011-01-01

    Full Text Available Abstract Carbon nanowalls (CNWs, two-dimensional "graphitic" platelets that are typically oriented vertically on a substrate, can exhibit similar properties as graphene. Growth of CNWs reported to date was exclusively carried out at a low pressure. Here, we report on the synthesis of CNWs at atmosphere pressure using "direct current plasma-enhanced chemical vapor deposition" by taking advantage of the high electric field generated in a pin-plate dc glow discharge. CNWs were grown on silicon, stainless steel, and copper substrates without deliberate introduction of catalysts. The as-grown CNW material was mainly mono- and few-layer graphene having patches of O-containing functional groups. However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing. A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth. The sensor responded to relatively low concentrations of NO2 (g and NH3 (g, thus suggesting high-quality CNWs that are useful for room temperature gas sensors. PACS: Graphene (81.05.ue, Chemical vapor deposition (81.15.Gh, Gas sensors (07.07.Df, Atmospheric pressure (92.60.hv

  13. Variations in atmospheric pressure as a source of errors in polychromatic X-ray experiments

    CERN Document Server

    Matjushin, A M

    2000-01-01

    The influence of the atmospheric pressure on the accuracy of energy diffractometry (ED), X-ray fluorescence analysis (XRF) using a semiconductor Si(Li) detector, polychromatic diffractometry without the energy dispersion (PDWED) using a coordinate detector has been considered. It is shown that in the interval of pressures 710-810 mm Hg, errors in the determination of interplanar spaces can reach 2% for PDWED, which is caused by the displacement of the maximum of spectral distribution due to changes in absorption by air gaps of the device, and by changes in the quantum efficiency of the coordinate detector. In the ED and XRF methods, changes in the spectrum lead to errors in the determination of relative intensities of diffraction and fluorescence peaks, respectively. The changes in integral intensity are about 1% and can be neglected in the majority of experiments. The curves of the displacement of the spectral distribution maximum and spectral changes were calculated as a function of the atmospheric pressure...

  14. Windowless transition between atmospheric pressure and high vacuum via differential pumping for synchrotron radiation applications.

    Energy Technology Data Exchange (ETDEWEB)

    Gog, T.; Casa, D. M.; Kuzmenko, I.; Krakora, R. J.; Bolin, T. B.; X-Ray Science Division

    2007-07-01

    A differential pump assembly is introduced which can provide a windowless transition between the full atmospheric pressure of an in-air sample environment and the high-vacuum region of a synchrotron radiation beamline, while providing a clear aperture of approximately 1 mm to pass through the X-ray beam from a modern third-generation synchrotron radiation source. This novel pump assembly is meant to be used as a substitute for an exit vacuum window on synchrotron beamlines, where the existence of such a window would negatively impact the coherent nature of the X-ray beam or would introduce parasitic scattering, distorting weak scattering signals from samples under study. It is found that the length of beam pipe necessary to reduce atmospheric pressure to below 10 mbar is only about 130 mm, making the expected photon transmission for hard X-rays through this pipe competitive with that of a regular Be beamline window. This result is due to turbulent flow dominating the first pumping stage, providing a mechanism of strong gas conductance limitation, which is further enhanced by introducing artificial surface roughness in the pipe. Successive reduction of pressure through the transitional flow regime into the high-vacuum region is accomplished over a length of several meters, using beam pipes of increasing diameter. While the pump assembly has not been tested with X-rays, possible applications are discussed in the context of coherent and small-angle scattering.

  15. In situ TEM studies of the shape evolution of Pd nanocrystals under oxygen and hydrogen environments at atmospheric pressure.

    Science.gov (United States)

    Zhang, Xun; Meng, Jun; Zhu, Beien; Yu, Jian; Zou, Shihui; Zhang, Ze; Gao, Yi; Wang, Yong

    2017-12-12

    We demonstrate an atomic scale TEM observation of shape evolutions of Pd nanocrystals under oxygen and hydrogen environments at atmospheric pressure. Combined with multi-scale structure reconstruction model calculations, the reshaping mechanism is fully understood.

  16. Assimilation of SLA along track observations in the Mediterranean with an oceanographic model forced by atmospheric pressure

    Directory of Open Access Journals (Sweden)

    S. Dobricic

    2012-09-01

    Full Text Available A large number of SLA observations at a high along track horizontal resolution are an important ingredient of the data assimilation in the Mediterranean Forecasting System (MFS. Recently, new higher-frequency SLA products have become available, and the atmospheric pressure forcing has been implemented in the numerical model used in the MFS data assimilation system. In a set of numerical experiments, we show that, in order to obtain the most accurate analyses, the ocean model should include the atmospheric pressure forcing and the observations should contain the atmospheric pressure signal. When the model is not forced by the atmospheric pressure, the high-frequency filtering of SLA observations, however, improves the quality of the SLA analyses. It is further shown by comparing the power density spectra of the model fields and observations that the model is able to extract the correct information from noisy observations even without their filtering during the pre-processing.

  17. Atmospheric pressure as a force that fills developing bones with marrow and air.

    Science.gov (United States)

    Kurbel, Sven; Radić, Radivoje; Kristek, Branka; Ivezić, Zdravko; Selthofer, Robert; Kotromanović, Zeljko

    2004-01-01

    Many theories try to explain the existence and function of paranasal sinuses. This paper is an attempt to correlate process of paranasal sinus development in human with bone pneumatization processes in animals. It is here proposed that this mechanism starts in utero and continues after birth. During endochondral development, a solid hyaline cartilage model transforms into long bones. Central chondrocytes hypertrophy and their lacunae become confluent. Dissolving of the cartilage intercellular matrix forms a primitive marrow cavity. It is soon invaded by the periostal bud. Once circulation is established in the developing bone, the dissolved hyaline matrix can be slowly washed away from the bone cavity. Circulation in the bone cavity can develop slight subatmospheric pressures, similar to negative interstitial pressures in subcutaneous tissues. The amniotic fluid conducts atmospheric pressure to the fetal body. The pressure is trying to fill enlarging bone cavities through the existing vascular openings, or to create new openings. Bone walls of developing paranasal bones are to weak to resist the pressure gradient on their walls. New openings form on the weakest spots allowing airway mucosa to form initial paranasal sinuses. The enlarging cavities of long bones that are remote from the body surface and airway also develop a slightly subatmospheric pressure that fills them with cellular elements. These elements enter bone through the feeding vessels and form bone marrow. During after birth skeletal growth, bone remodeling shapes paranasal sinuses in a process of slow evolution that do not require measurable pressure gradients. When two sinuses come in vicinity, their growth rate declines, since the remaining thin and fragile bone lamella between them does not retract anymore.

  18. An open port sampling interface for liquid introduction atmospheric pressure ionization mass spectrometry.

    Science.gov (United States)

    Van Berkel, Gary J; Kertesz, Vilmos

    2015-10-15

    A simple method to introduce unprocessed samples into a solvent for rapid characterization by liquid introduction atmospheric pressure ionization mass spectrometry has been lacking. The continuous flow, self-cleaning open port sampling interface introduced here fills this void. The open port sampling interface used a vertically aligned, co-axial tube arrangement enabling solvent delivery to the sampling end of the device through the tubing annulus and solvent aspiration down the center tube and into the ionization source of the mass spectrometer via the commercial APCI emitter probe. The solvent delivery rate to the interface was set to exceed the aspiration rate, creating a continuous sampling interface along with a constant, self-cleaning spillover of solvent from the top of the probe. Using the open port sampling interface with positive ion mode APCI and a hybrid quadrupole time-of-flight mass spectrometer, rapid, direct sampling and analysis possibilities are exemplified with plastics, ballpoint and felt tip ink pens, skin, and vegetable oils. These results demonstrated that the open port sampling interface could be used as a simple, versatile and self-cleaning system to rapidly introduce multiple types of unprocessed, sometimes highly concentrated and complex, samples into a solvent flow stream for subsequent ionization and analysis by mass spectrometry. The basic setup presented here could be incorporated with any self-aspirating liquid introduction ionization source (e.g., ESI, APCI, APPI, ICP, etc.) or any type of atmospheric pressure sampling-ready mass spectrometer system. The open port sampling interface provides a means to introduce and quickly analyze unprocessed solid or liquid samples with the liquid introduction atmospheric pressure ionization source without fear of sampling interface or ionization source contamination. Copyright © 2015 John Wiley & Sons, Ltd.

  19. Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

    Energy Technology Data Exchange (ETDEWEB)

    Lu, X., E-mail: luxinpei@hotmail.com [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Naidis, G.V. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Laroussi, M. [Plasma Engineering & Medicine Institute, Old Dominion University, Norfolk, VA 23529 (United States); Reuter, S. [Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Strasse 2, 17489 Greifswald (Germany); Graves, D.B. [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720 (United States); Ostrikov, K. [Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000 (Australia); School of Physics, Chemistry, and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Commonwealth Scientific and Industrial Research Organization, P.O.Box 218, Lindfield, NSW 2070 (Australia); School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia)

    2016-05-04

    Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmospheric-pressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, time-resolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors’ vision for the emerging convergence trends across several disciplines and application domains is presented to

  20. A Novel Atmospheric Pressure Plasma Fluidized Bed and Its Application in Mutation of Plant Seeds

    Science.gov (United States)

    Chen, Guang-Liang; Fan, Song-Hua; Li, Chun-Ling; Gu, Wei-Chao; Feng, Wen-Ran; Zhang, Gu-Ling; Wang, Jiu-Li; Latif, K.; Zhang, Shu-Gen; Wang, Zhen-Quan; Han, Er-Li; Fu, Ya-Bo; Yang, Si-Ze

    2005-08-01

    An atmospheric pressure plasma fluidized bed (APPFB) is designed to generate plasma using a dielectric barrier discharge (DBD) with one liquid electrode. In the APPFB system, the physical properties of DBD discharge and its application in plant-seed mutating are studied fundamentally. The results show that the generated plasma is a typical glow discharge free from filament and arc plasma, and the macro-temperature of the plasma fluidized bed is nearly at room temperature. There are no obvious changes in the pimientos when their seeds are treated by APPFB, but great changes are found for coxcombs.

  1. Fluoropolymer coated alanine films treated by atmospheric pressure plasmas − In comparison with gamma irradiation

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Bardenshtein, Alexander; Morgen, Per

    2017-01-01

    Fluoropolymer coated alanine films are treated by a dielectric barrier discharge and a gliding arc at atmospheric pressure as well as with gamma irradiation. The film surfaces and the underlying bulk materials are characterized before and after each treatment. The fluorine content decreases...... and the oxygen content increases at the fluoropolymer surfaces, while deposition of specific plasma energies in the alanine films is detected by electron paramagnetic resonance spectroscopy, indicating that not only the fluoropolymer surfaces but also the bulk alanine materials are modified. Differences...... of surface and bulk modification effects between the two plasma treatments are discussed in detail....

  2. Surface properties and hydrophobic recovery of polymers treated by atmospheric-pressure plasma

    Science.gov (United States)

    Borcia, C.; Punga, I. L.; Borcia, G.

    2014-10-01

    This paper provides an analysis on the relation between plasma effects on polymers exposed to inert gas atmospheric-pressure plasma, polymer structure characteristics and surface recovery during post-processing ageing. Polymers offering variety of structure, functionality, degree of oxidation, polarity, crystallinity are tested, using contact angle, XPS, XRD and solvent absorption measurement, thus exploring the relationship linking the surface polarity, the chemical structure and composition contribution in the combined functionalization/crosslinking surface modification mechanisms of plasma-exposed polymers. The limiting level of modification attainable, the surface stability and the factors controlling these are examined, concluding on the plasma capacity to provide operational stability for modified polymer surfaces.

  3. Barrier discharges driven by sub-microsecond pulses at atmospheric pressure: Breakdown manipulation by pulse width

    Energy Technology Data Exchange (ETDEWEB)

    Hoder, Tomas; Hoeft, Hans; Kettlitz, Manfred; Weltmann, Klaus-Dieter; Brandenburg, Ronny [Leibniz Institute for Plasma Science and Technology, INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2012-07-15

    Barrier discharges at atmospheric pressure in nitrogen-oxygen mixture powered by high voltage pulses of widths between 10 {mu}s and 200 ns were investigated. The development of the microdischarges on rising and falling slopes was recorded by streak and intensified CCD cameras simultaneously. The breakdown on the falling slope strongly depends on the pulse width. As a result of pulse width variation the starting point of ignition changes and positive and negative streamers occur simultaneously in the falling slope. The observed effect is caused by the electric field rearrangement in the gap due to the different positive ion densities related to their gap crossing times.

  4. Rapid Atmospheric-Pressure-Plasma-Jet Processed Porous Materials for Energy Harvesting and Storage Devices

    Directory of Open Access Journals (Sweden)

    Jian-Zhang Chen

    2015-01-01

    Full Text Available Atmospheric pressure plasma jet (APPJ technology is a versatile technology that has been applied in many energy harvesting and storage devices. This feature article provides an overview of the advances in APPJ technology and its application to solar cells and batteries. The ultrafast APPJ sintering of nanoporous oxides and 3D reduced graphene oxide nanosheets with accompanying optical emission spectroscopy analyses are described in detail. The applications of these nanoporous materials to photoanodes and counter electrodes of dye-sensitized solar cells are described. An ultrashort treatment (1 min on graphite felt electrodes of flow batteries also significantly improves the energy efficiency.

  5. Small mass spectrometer with extended measurement capabilities at high pressures. [for planetary atmosphere analysis

    Science.gov (United States)

    Von Zahn, U.; Mauersberger, K.

    1978-01-01

    For the in situ investigation of planetary atmospheres a small Mattauch-Herzog mass spectrometer has been developed. Its high-pressure performance has been improved by incorporating differential pumping between the ion source and the analyzing fields, shortening the path-length as well as increasing the extraction field in the ion source. In addition doubly ionized and dissociated ions are used for mass analysis. These measures make possible operation up to 0.01 millibars. Results of laboratory tests related to linearity, dynamic range, and mass resolution are presented, in particular for CO2.

  6. epsilon-Fe2O3 nanoparticles synthesized in atmospheric-pressure microwave torch

    OpenAIRE

    David Bohumil; Pizúrová Naděžda; Synek Petr; Kudrle Vít; Jašek Ondřej; Schneeweiss Oldřich

    2014-01-01

    The article reports on epsilon-Fe2O3 nanoparticles synthesized in a single step by atmospheric-pressure microwave torch discharge using gaseous precursors only. Morphology and composition of the as-synthesized nanopowder were studied by HR-TEM, XRD, and Mossbauer spectroscopy. In the studied nanopowder, epsilon-Fe2O3 phase (d(xRD)=25 nm, 32 wt%) together with alpha-Fe2O3 and gamma-Fe2O3 phases was found. The characteristic epsilon-Fe2O3 and alpha/gamma-Fe2O3 sextets in the Mossbauer spectra m...

  7. Atmospheric Pressure Plasma Jet as a Dry Alternative to Inkjet Printing in Flexible Electronics

    Science.gov (United States)

    Gandhiraman, Ram Prasad; Lopez, Arlene; Koehne, Jessica; Meyyappan, M.

    2016-01-01

    We have developed an atmospheric pressure plasma jet printing system that works at room temperature to 50 deg C unlike conventional aerosol assisted techniques which require a high temperature sintering step to obtain desired thin films. Multiple jets can be configured to increase throughput or to deposit multiple materials, and the jet(s) can be moved across large areas using a x-y stage. The plasma jet has been used to deposit carbon nanotubes, graphene, silver nanowires, copper nanoparticles and other materials on substrates such as paper, cotton, plastic and thin metal foils.

  8. Characterization of the improvised explosive urea nitrate using electrospray ionization and atmospheric pressure chemical ionization.

    Science.gov (United States)

    Tamiri, Tsippy

    2005-01-01

    Mass spectra of urea nitrate were measured in electrospray ionization and in atmospheric pressure chemical ionization in the negative mode. In both ionization methods two characteristic adduct ions containing the intact molecule [urea nitrate+NO3]- and [urea nitrate+HNO3+NO3]- are shown. The structure of the two adduct ions was deduced using measurements of isotopically labeled urea nitrate. Collision-induced dissociation measurements of the adduct ions show typical losses enabling the identification of urea nitrate in trace amounts. Using these methods urea nitrate was identified in real cases. Copyright (c) 2005 John Wiley & Sons, Ltd.

  9. Crednerite-CuMnO2 thin films prepared using atmospheric pressure plasma annealing

    Science.gov (United States)

    Chen, Hong-Ying; Lin, Yu-Chang; Lee, Jiann-Shing

    2015-05-01

    This study reports the preparation of crednerite-CuMnO2 thin films using atmospheric pressure plasma annealing. The pristine thin films were deposited onto a quartz substrate using the sol-gel process. The specimens were then annealed using atmospheric pressure plasma at N2-(0-20%)O2 for 20 min. Crednerite-CuMnO2 thin films were obtained using atmospheric pressure plasma annealing at N2-5%O2 and N2-10%O2. The lattice parameters of the thin films were a = 0.5574-0.5580 nm, b = 0.2874-0.2879 nm, c = 0.5878-0.5881 nm, and β = 104.15-104.25°, which agree well with previous reports. The Raman shifts of the crednerite-CuMnO2 thin films were 688 ± 2 cm-1, 381 ± 2 cm-1, and 314 ± 2 cm-1. The binding energy of Cu-2p spectrum of the crednerite-CuMnO2 thin films was 932.3 ± 0.2 eV representing the Cu+ in the thin films. The binding energies of Mn-3p spectrum were 48.1 ± 0.2 eV (Mn3+) and 50.0 ± 0.2 eV (Mn4+). Furthermore, the cation distribution in the thin films was Cu+1.0(Mn3+0.6Mn4+0.4)O2 from the X-ray photoelectron spectroscopy measurement. When the crednerite-CuMnO2 phase was formed, the surface morphology exhibited a compact/dense granular morphology. The optical bandgap of the crednerite-CuMnO2 thin films was 2.6 eV, 2.8 eV, and 3.5 eV. In addition, the resistivity of the crednerite-CuMnO2 thin films was (2.61-2.65) × 104 Ω cm, which is consistent with previous literature reports. Moreover, the activation energies for the carrier conduction in the crednerite-CuMnO2 thin films were 0.10-0.12 eV. Hence, an atmospheric pressure plasma annealing offers a green, economic, effective and feasible method for preparing crednerite-CuMnO2 thin films.

  10. Spatial and temporal evolutions of ozone in a nanosecond pulse corona discharge at atmospheric pressure

    Science.gov (United States)

    Duten, X.; Redolfi, M.; Aggadi, N.; Vega, A.; Hassouni, K.

    2011-10-01

    This paper deals with the experimental determination of the spatial and temporal evolutions of the ozone concentration in an atmospheric pressure pulsed plasma, working in the nanosecond regime. We observed that ozone was produced in the localized region of the streamer. The ozone transport requires a characteristic time well above the millisecond. The numerical modelling of the streamer expansion confirms that the hydrodynamic expansion of the filamentary discharge region during the streamer propagation does not lead to a significant transport of atomic oxygen and ozone. It appears therefore that only diffusional transport can take place, which requires a characteristic time of the order of 50 ms.

  11. Cellular and molecular responses of Neurospora crassa to non-thermal plasma at atmospheric pressure

    Science.gov (United States)

    Park, Gyungsoon; Ryu, Young H.; Hong, Young J.; Choi, Eun H.; Uhm, Han S.

    2012-02-01

    Filamentous fungi have been rarely explored in terms of plasma treatments. This letter presents the cellular and molecular responses of the filamentous fungus Neurospora crassa to an argon plasma jet at atmospheric pressure. The viability and cell morphology of N. crassa spores exposed to plasma were both significantly reduced depending on the exposure time when treated in water. The intracellular genomic DNA content was dramatically reduced in fungal tissues after a plasma treatment and the transcription factor tah-3 was found to be required for fungal tolerance to a harsh plasma environment.

  12. Decontamination of a rotating cutting tool during operation by means of atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank; Kusano, Yukihiro; Hansen, F.

    2010-01-01

    The decontamination of a rotating cutting tool used for slicing in the meat industry by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua...... of the whole cutting tool. A log 5 reduction of L. innocua is obtained after 340 s of plasma operation. The temperature of the knife after treatment was found to be below 30 °C. The design of the setup allows a decontamination during slicing operation....

  13. Porous tungsten prepared by atmospheric-pressure chemical vapor deposition with WF6 and its characterization

    Science.gov (United States)

    Li, Ying; Yu, Xiaodong; Tan, Chengwen; Wang, Fuchi; Ma, Honglei; Yue, Jintao

    2017-05-01

    Porous tungsten (W) is used in aeronautic and aerospace engineering, power electronics field and metallurgical industry. In this study, porous W with 98wt% W was prepared on a carbon foam substrate by atmospheric-pressure chemical vapor deposition (CVD) with tungsten fluoride (WF6) as the precursor. The porous W with 78.1346% porosity displayed a pure α-W phase and the uniform surface. The mode pore diameter of porous W is 208.0 µm. In a compression test, the fracture strength of porous W is 20.3 MPa.

  14. Never neglect the atmospheric pressure effect on a brain with a skull defect

    Science.gov (United States)

    Wee, Hsiao-Yue; Kuo, Jinn-Rung

    2014-01-01

    Herein, we report an unusual case of a patient who presented with a severe, sinking skin flap after a decompressive craniectomy and ventriculoperitoneal shunt surgery due to a traumatic brain injury. After cranioplasty, the patient’s neurological deficiency improved and was confirmed by transcranial Doppler sonography. In addition to discussing the pathogenesis of the sinking skin flap, we emphasize the importance of cranioplasty for neurological improvement and remind the surgeon to “never neglect the atmospheric pressure effect on a brain with a skull defect”. PMID:24741332

  15. Atmospheric-Pressure Plasma Jet Surface Treatment for Use in Improving Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-06

    Atmospheric-pressure plasma jets (APPJs) are a method of plasma treatment that plays an important role in material processing and modifying surface properties of materials, especially polymers. Gas plasmas react with polymer surfaces in numerous ways such as oxidation, radical formation, degradation, and promotion of cross-linking. Because of this, gas and plasma conditions can be explored for chosen processes to maximize desired properties. The purpose of this study is to investigate plasma parameters in order to modify surface properties for improved adhesion between aluminum and epoxy substrates using two types of adhesives. The background, results to date, and future work will be discussed.

  16. Surface discharge induced interactions of filaments in argon dielectric barrier discharge at atmospheric pressure

    Science.gov (United States)

    Li, Xuechen; Zhang, Panpan; Chu, Jingdi; Zhang, Qi; Lin, Xiaotong; Jia, Pengying; Dong, Lifang

    2017-10-01

    A needle-plate geometry is used to generate two barrier-discharge filaments composed of volume discharge and surface discharge in atmospheric pressure argon, interactions of which are investigated for the first time on the nanosecond timescale using an intensified charge-coupled device. The results indicate that the onset of volume discharges for the two filaments have a periodical discharge sequence, which implies interactions of the two filaments. Moreover, strong interactions of the two filaments are controlled through surface discharges, one of which is induced by that of the other filament during the positive discharge. Different from repulsive streamers, counter-propagating streamers are attractive between the two filaments.

  17. DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xu; Ptasinska, Sylwia [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Klas, Matej [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Liu, Yueying [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Sharon Stack, M. [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2013-06-10

    The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

  18. Rapid inactivation of Penicillium digitatum spores using high-density nonequilibrium atmospheric pressure plasma

    Science.gov (United States)

    Iseki, Sachiko; Ohta, Takayuki; Aomatsu, Akiyoshi; Ito, Masafumi; Kano, Hiroyuki; Higashijima, Yasuhiro; Hori, Masaru

    2010-04-01

    A promising, environmentally safe method for inactivating fungal spores of Penicillium digitatum, a difficult-to-inactivate food spoilage microorganism, was developed using a high-density nonequilibrium atmospheric pressure plasma (NEAPP). The NEAPP employing Ar gas had a high electron density on the order of 1015 cm-3. The spores were successfully and rapidly inactivated using the NEAPP, with a decimal reduction time in spores (D value) of 1.7 min. The contributions of ozone and UV radiation on the inactivation of the spores were evaluated and concluded to be not dominant, which was fundamentally different from the conventional sterilizations.

  19. Application of an atmospheric pressure sampling mass spectrometer to chlorination reactions

    Science.gov (United States)

    Jacobson, N. S.

    1986-01-01

    An atmospheric pressure mass spectrometric sampling system, based on a free jet expansion was used to study certain M-Cl-O reactions at high temperatures. The apparatus enables the volatile species from a 1-atm chemical process to be directly identified with a mass spectrometer which operates at approx. 10 to the minus 8th power torr. Studies for both pure metals and alloys are discussed. It is shown that this mass spectrometer system aids in identifying the volatile species, and provides fundamental information on the reaction mechanism.

  20. Evaluation of Vapor Pressure Estimation Methods for Use in Simulating the Dynamic of Atmospheric Organic Aerosols

    Directory of Open Access Journals (Sweden)

    A. J. Komkoua Mbienda

    2013-01-01

    Lee and Kesler (LK, and Ambrose-Walton (AW methods for estimating vapor pressures ( are tested against experimental data for a set of volatile organic compounds (VOC. required to determine gas-particle partitioning of such organic compounds is used as a parameter for simulating the dynamic of atmospheric aerosols. Here, we use the structure-property relationships of VOC to estimate . The accuracy of each of the aforementioned methods is also assessed for each class of compounds (hydrocarbons, monofunctionalized, difunctionalized, and tri- and more functionalized volatile organic species. It is found that the best method for each VOC depends on its functionality.

  1. Energy distribution of runaway electrons generated by a nanosecond discharge in atmospheric-pressure air

    Science.gov (United States)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Kostyrya, I. D.; Lomaev, M. I.; Petin, V. K.; Rybka, D. V.; Shlyakhtun, S. V.

    2008-12-01

    The spectra of an ultrashort avalanche electron beam generated by a nanosecond discharge in atmospheric-pressure air were investigated. The temporal characteristics of the beam current pulses, gap voltage, and discharge current in a gas diode were measured with a time resolution of ˜0.1 ns. A simple technique was developed for recovering electron spectra from the curves of beam attenuation by aluminum foils. The effect of the cathode design, electrode gap length, and generator parameters on the electron spectra were studied using seven setups. It is shown that generation of electrons with anomalously high energies requires the use of cathodes with increased curvature radius.

  2. Controlled nanostructured silver coated surfaces by atmospheric pressure chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sheel, D.W.; Brook, L.A.; Yates, H.M. [Institute for Materials Research, Salford University, Manchester, M5 4 WT (United Kingdom)

    2008-02-15

    Thin film silver has been widely reported for its interesting properties. In this paper we describe a route to produce controlled nanostructured silver layers. A combination of Flame Assisted Chemical Vapour Deposition at atmospheric pressure, with low cost and a low toxicity silver precursor, was used to generate coatings of structured silver surfaces on glass. This approach gives a high degree of control of surface structure, density and topography. These layers have potential applications in areas such as catalysis, photo-activity and for biocidal surfaces. Our results indicate very high biocidal activity where the nano-structure is proposed as playing a significant role. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  3. Characterization of atmospheric pressure plasma treated wool/cashmere textiles: Treatment in nitrogen

    Science.gov (United States)

    Zanini, Stefano; Citterio, Attilio; Leonardi, Gabriella; Riccardi, Claudia

    2018-01-01

    We performed atmospheric pressure plasma treatments of wool/cashmere (15/85%) textiles with a dielectric barrier discharge (DBD) in nitrogen. The chemical properties of the plasma treated samples were investigated with attenuated total reflectance Fourier transform infrared (FTIR/ATR) spectroscopy, X-ray photoelectron microscopy (XPS), and fatty acid gas chromatographic analysis. Changes in mechanical properties and tactile performance of textiles after the plasma treatment were determined using the KES-F system. The analyses reveal significant surface modification of the treated fabrics, which enhances their surface wettability.

  4. Inversion effects on wind and surface pressure in atmospheric front propagation simulation with a hyperbolic model

    Science.gov (United States)

    Yudin, M. S.

    2017-11-01

    In this paper the effects of an inversion layer in a stratified atmosphere on the surface wind speed and pressure are investigated with models based on the compressible Navier-Stokes equations in two dimensions. Artificial compressibility is introduced into the models in order to make the governing equations hyperbolic. For comparison with available simulation data, the physical processes under study are assumed to be adiabatic. Plain orography is considered in surface pressure simulations with a finite-difference version of the model, while surface wind speed effects are estimated in artificial cold front propagation over a hill with a finite-element version of the model. The front surface is described in both models by an equation for advection of a scalar substance, which is solved with a third-order semi-Lagrangian procedure. The results of simulations show various meteorological effects in agreement with observations and in accordance with a theory proposed by Charba [3].

  5. Rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser.

    Science.gov (United States)

    Qu, Yanchen; Ren, Deming; Hu, Xiaoyong; Liu, Fengmei; Zhao, Jingshan

    2002-08-20

    An experimental study of a rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser is reported. To rapidly shift laser wavelengths over selected transitions in the 9-11 microm wavelength region, we have utilized a high-frequency stepping motor and a diffraction grating. The laser is highly automated with a monolithic microprocessor controlled laser line selection. For the achievement of stable laser output, a system of laser excitation with a voltage of 10 kV, providing effective surface corona preionization and allowing one to work at various gas pressures, is utilized. Laser operation at 59 emission lines of the CO2 molecule rotational transition is obtained and at 51 lines, the pulse energy of laser radiation exceeds 30 mJ. The system can be tuned between two different rotational lines spanning the wavelength range from 9.2 to 10.8 microm within 10 ms.

  6. Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

    Science.gov (United States)

    Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

    2015-01-01

    Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

  7. Super-atmospheric pressure electrospray ion source: applied to aqueous solution.

    Science.gov (United States)

    Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

    2011-12-01

    This is a follow-up paper of our previous report on an ion source, which was operated at an operating pressure higher than the atmospheric pressure. Besides having more working gas for desolvation, the reduction of mean free path of electrons in a higher pressure environment increases the threshold voltage for gaseous breakdown, thus enabling a stable electrospray for the sample solution with high surface tension without the occurrence of electric discharge. In our previous work, the ion source was not coupled directly to the mass spectrometer and significant amount of ions were lost before entering the vacuum of the mass spectrometer. In this paper, we report the new design of our second prototype in which, by using a modified ion transport capillary, the pressurized ESI ion source was coupled directly to the first pumping stage of the mass spectrometer without additional modification on the vacuum pumping system. Demonstrations of the new ion source on the sensitive detection of native proteins from aqueous solution in both positive and negative ion modes are presented. © American Society for Mass Spectrometry, 2011

  8. Minimally-Invasive Gene Transfection by Chemical and Physical Interaction of Atmospheric Pressure Plasma Flow

    Science.gov (United States)

    Kaneko, Toshiro

    2014-10-01

    Non-equilibrium atmospheric pressure plasma irradiated to the living-cell is investigated for medical applications such as gene transfection, which is expected to play an important role in molecular biology, gene therapy, and creation of induced pluripotent stem (iPS) cells. However, the conventional gene transfection using the plasma has some problems that the cell viability is low and the genes cannot be transferred into some specific lipid cells, which is attributed to the unknown mechanism of the gene transfection using the plasma. Therefore, the time-controlled atmospheric pressure plasma flow is generated and irradiated to the living-cell suspended solution for clarifying the transfection mechanism toward developing highly-efficient and minimally- invasive gene transfection system. In this experiment, fluorescent dye YOYO-1 is used as the simulated gene and LIVE/DEAD Stain is simultaneously used for cell viability assay. By the fluorescence image, the transfection efficiency is calculated as the ratio of the number of transferred and surviving cells to total cell count. It is clarified that the transfection efficiency is significantly increased by the short-time (90%). This result indicates that the physical effects such as the electric field caused by the charged particles arriving at the surface of the cell membrane, and chemical effects associated with plasma-activated products in solution act synergistically to enhance the cell-membrane transport with low-damage. This work was supported by JSPS KAKENHI Grant Number 24108004.

  9. Augmented survival of Neisseria gonorrhoeae within biofilms: exposure to atmospheric pressure non-thermal plasmas.

    Science.gov (United States)

    Xu, L; Tu, Y; Yu, Y; Tan, M; Li, J; Chen, H

    2011-01-01

    Bacteria embedded within biofilms present a challenge to surface decontamination by conventional means. Atmospheric pressure non-thermal plasma processes have emerged as a promising approach to overcoming this problem. We used atmospheric pressure non-equilibrium plasmas (APNPs) to assess planktonic versus biofilm-resident bacterial (Neisseria gonorrhoeae) susceptibility to treatment. The decontamination efficiency of the process was evaluated against bacteria embedded within a biofilm, as well as planktonic cells placed on a glass surface. Bacterial survival was assessed using a combination of colony forming unit (CFU) ability and vital staining with a combination of SYTO9 plus propidium iodide. Both methods revealed an increased resistance of biofilm-resident bacteria compared with planktonic cells, after a 20-min exposure to the APNPs. Transmission electron microscopy revealed disruption and damage to the cell wall, resulting in the release of cytoplasmic compounds, alterations in morphology, and a decrease in cell volume, indicating that APNPs may affect the cell wall. Present results show that biofilm-resident bacteria demonstrate augmented survival when exposed to APNP treatment and therefore that decontamination procedures should take into account this survival when evaluating surface decontamination measures.

  10. Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique

    Directory of Open Access Journals (Sweden)

    Choon-Sang Park

    2016-01-01

    Full Text Available This work presents a study on the preparation of plasma-polymerized aniline (pPANI nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, gas chromatography-mass spectrometry (GC-MS, and gel permeation chromatography (GPC techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight (Mw, about 533 kDa with 1.9 polydispersity index (PDI. This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.

  11. Development of compact ion gun under atmospheric pressure X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Hana, Nurul, E-mail: 1033340426h@kindai.ac.jp [Graduate School of Engineering, Kinki University, 3-4-1 Kowakae, Higashi Osaka, Osaka 577-8502 (Japan); Tsutsui, Hidenori; Matsutani, Takaomi [Graduate School of Engineering, Kinki University, 3-4-1 Kowakae, Higashi Osaka, Osaka 577-8502 (Japan); Hosokawa, Yoshinori [X-Ray Precision Inc., 2 Miyanohigashi, Kisshoin, Minamiku, Kyoto 601-8510 (Japan)

    2012-02-01

    A highly efficient and highly stable compact ion gun (less than 10 Multiplication-Sign 10 Multiplication-Sign 5 cm) operable under atmospheric pressure was developed for environmental measurements and materials technology applications. Soft X-ray ionization was used as an ion source. In this work, soft X-rays were generated from a beryllium/titanium target irradiated by 9 keV thermal electrons. For a nitrogen assist gas flow rate of 500 ml/min and an acceleration voltage of 3.9 kV, the highest average ion current was 1.34 nA and a current stability of {+-}6% over 10 min was obtained. A high frequency electric field was applied to the electrode in the X-ray ionization chamber in order to enhance the ion current. The ion current increased by a factor of 1.6 compared to the current in the absence of the high frequency electric field. The ion gun developed here was employed to deposit a silicon carbonitride (SiCN) film on silicon and copper substrates by using nitrogen ions and hexamethyldisilane under atmospheric pressure conditions. The deposition of a hydrogenated SiCO and SiCN mixture film was confirmed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.

  12. Electrical and optical characteristics of atmospheric pressure plasma needle jet driven by neon trasformer

    Science.gov (United States)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Soon, Chin Fhong; Sahdan, Mohd Zainizan; Lias, Jais; Mamat, Mohamad Hafiz; Rusop, Mohamad; Nayan, Nafarizal

    2017-09-01

    The atmospheric pressure plasma needle jet driven by double sinusoidal waveform of neon transformer is reported in this paper. The commercial neon transformer produces about 5 kV of peak sinusoidal voltages and 35 kHz of frequency. Argon gas has been used as discharge gas for this system since the discharge was easily developed rather than using helium gas. In addition, argon gas is three times cheaper than helium gas. The electrical property of the argon discharge has been analyzed in details by measuring its voltage, current and power during the discharge process. Interestingly, it has been found that the total power on the inner needle electrode was slightly lower than that of outer electrode. This may be due to the polarization charges that occurred at inner needle electrode. Then, further investigation to understand the discharge properties was carried out using optical emission spectroscopy (OES) analysis. During OES measurements, two positions of plasma discharge are measured by aligning the quartz optical lens and spectrometer fiber. The OH emission intensity was found higher than that of N2 at the plasma orifice. However, OH emission intensity was lower at 1.5 cm distance from orifice which may be due to penning ionization effect. These results and understanding are essential for surface modification and biomedical applications of atmospheric pressure plasma needle jet.

  13. Surface modification of polyester synthetic leather with tetramethylsilane by atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kan, C.W., E-mail: tccwk@polyu.edu.hk [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Kwong, C.H. [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Ng, S.P. [Hong Kong Community College, The Hong Kong Polytechnic University (Hong Kong)

    2015-08-15

    Highlights: • Atmospheric pressure plasma treatment improved surface performance of polyester synthetic leather with tetramethylsilane. • XPS and FTIR confirmed the deposition of organosilanes on the sample's surface. • Contact angle increases to 138° after plasma treatment. - Abstract: Much works have been done on synthetic materials but scarcely on synthetic leather owing to its surface structures in terms of porosity and roughness. This paper examines the use of atmospheric pressure plasma (APP) treatment for improving the surface performance of polyester synthetic leather by use of a precursor, tetramethylsilane (TMS). Plasma deposition is regarded as an effective, simple and single-step method with low pollution. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) confirm the deposition of organosilanes on the sample's surface. The results showed that under a particular combination of treatment parameters, a hydrophobic surface was achieved on the APP treated sample with sessile drop static contact angle of 138°. The hydrophobic surface is stable without hydrophilic recovery 30 days after plasma treatment.

  14. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    Science.gov (United States)

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

    2013-02-01

    Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  15. Separated Type Atmospheric Pressure Plasma Microjets Array for Maskless Microscale Etching

    Directory of Open Access Journals (Sweden)

    Yichuan Dai

    2017-06-01

    Full Text Available Maskless etching approaches such as microdischarges and atmospheric pressure plasma jets (APPJs have been studied recently. Nonetheless, a simple, long lifetime, and efficient maskless etching method is still a challenge. In this work, a separated type maskless etching system based on atmospheric pressure He/O2 plasma jet and microfabricated Micro Electro Mechanical Systems (MEMS nozzle have been developed with advantages of simple-structure, flexibility, and parallel processing capacity. The plasma was generated in the glass tube, forming the micron level plasma jet between the nozzle and the surface of polymer. The plasma microjet was capable of removing photoresist without masks since it contains oxygen reactive species verified by spectra measurement. The experimental results illustrated that different features of microholes etched by plasma microjet could be achieved by controlling the distance between the nozzle and the substrate, additive oxygen ratio, and etch time, the result of which is consistent with the analysis result of plasma spectra. In addition, a parallel etching process was also realized by plasma microjets array.

  16. Effects of atmospheric pressure plasma jet with floating electrode on murine melanoma and fibroblast cells

    Science.gov (United States)

    Xu, G.; Liu, J.; Yao, C.; Chen, S.; Lin, F.; Li, P.; Shi, X.; Zhang, Guan-Jun

    2017-08-01

    Atmospheric pressure cold plasma jets have been recently shown as a highly promising tool in certain cancer therapies. In this paper, an atmospheric pressure plasma jet (APPJ) with a one inner floating and two outer electrode configuration using helium gas for medical applications is developed. Subjected to a range of applied voltages with a frequency of 19.8 kHz at a fixed rate of gas flow (i.e., 3 l/min), electrical and optical characteristics of the APPJ are investigated. Compared with the device only with two outer electrodes, higher discharge current, longer jet, and more active species in the plasma plume at the same applied voltage together with the lower gas breakdown voltage can be achieved through embedding a floating inner electrode. Employing the APPJ with a floating electrode, the effects of identical plasma treatment time durations on murine melanoma cancer and normal fibroblast cells cultured in vitro are evaluated. The results of cell viability, cell apoptosis, and DNA damage detection show that the plasma can inactivate melanoma cells in a time-dependent manner from 10 s to 60 s compared with the control group (p melanoma cells at the same treatment time. The different basal reactive oxygen species level and antioxidant superoxide dismutase level of two kinds of cells may account for their different responses towards the identical plasma exposure.

  17. Non-thermal atmospheric pressure plasmas as a novel candidate for preventive therapy of melanoma.

    Science.gov (United States)

    Omata, Yasuhiro; Iida, Machiko; Yajima, Ichiro; Takeda, Kozue; Ohgami, Nobutaka; Hori, Masaru; Kato, Masashi

    2014-09-01

    Due to the increased ultraviolet radiation, the incidence of melanoma is increasing worldwide more than that of any other cancer. In this study, the effects of irradiation of non-thermal atmospheric pressure plasmas (NEAPPs) on benign melanocytic tumors from our original hairless model mice (HL-RET-mice), in which benign melanocytic tumors and melanomas spontaneously develop in the skin stepwise, were examined. Expression levels of melanoma cell adhesion molecule (MCAM) and matrix metalloproteinase-2 (MMP-2) mRNA in melanomas were higher than those in benign melanocytic tumors in the mice. Repeated irradiation of non-thermal atmospheric pressure plasmas (NEAPPs) for the benign tumors decreased the expression levels of MCAM and MMP-2 mRNA in the tumors from the mice. Previous studies showed that MCAM sites are upstream of MMP-2, that MCAM regulates transcription of MMP-2 in melanoma cells and that MMP-2 is associated with the conversion of a benign tumor to a malignant tumor. Therefore, our results suggest that the NEAPP irradiation-mediated decrease in the expression level of MMP-2 in benign melanocytic tumors is associated with decreased expression levels of MCAM. Moreover, NEAPP irradiation might be a potential candidate for therapy to prevent melanoma development through suppression of malignant conversion in benign melanocytic tumors.

  18. Sterilization by negative and positive DC plasma with a micro discharge gap at atmospheric pressure

    Science.gov (United States)

    Li, Hua; Jiang, Lin-Xiu; Jiang, Yong-Rong; Zhu, Jian-Min; Chen, Zhen-Cheng

    2017-11-01

    A new needle-to-droplet electrode structure with a micro discharge gap (2 mm) was designed to achieve direct current (DC) discharge plasma in ambient air with the aim of using the plasma to sterilize liquids. Without using noble gases or an external air flow, we succeeded in generating both a negative and positive DC plasma at atmospheric pressure. The plasma was driven by a 0 to ‑20,000 V, 100 W DC power supply. A stainless steel needle with a tip diameter of ˜ 50μm and a 200-μL droplet of bacteria-containing liquid served as the electrodes. At atmospheric pressure and room temperature (23∘C), utilizing the negative DC plasma, the discharge time lasted 10 s; the results showed that the higher the discharge voltage, the more efficient the sterilization effect. Conversely, when we applied a voltage of ‑5.5 kV, we found that the sterilization effect was more efficient for longer discharge times. Our findings demonstrate that Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) can be killed in about 30 s. Our experiments show that our sterilization method required less time and was more efficient for positive than for negative DC plasma under the same conditions.

  19. Single short-column liquid chromatography with atmospheric pressure chemical ionization - (tandem) mass spectrometric detection for trace environmental analysis.

    NARCIS (Netherlands)

    Hogenboom, A.C.; Vreuls, J.J.; Rontree, J.A.; van Baar, B.L.M.; Niessen, W.M.A.; Brinkman, U.A.T.; Slobodník, J.

    1996-01-01

    Single short, i.e. ca 2-cm long, high-pressure-packed columns coupled with mass spectrometric (MS) or tandem MS detection enable rapid trace-level determination and identification of environmental pollutants in water samples. In this study an atmospheric pressure chemical ionization (APCI) interface

  20. Generation of micro-jet atmospheric pressure plasmas and study of their characteristics

    Science.gov (United States)

    Kim, Danbee; Rhee, J. K.; Gweon, B.; Choe, W.

    2006-10-01

    Low temperature micro-plasmas of about 360 μm in radius and were produced in the ambient air at tens of kHz using a pin electrode with and without a plane electrode. A pin electrode was placed in a pyrex tube, through which a helium gas was supplied. In the case of a pin electrode to a dielectric-covered plane electrode set up, a cone-shaped plasma was generated due to the presence of the dielectric material. It was shown that the discharge mode, plasma size, and gas temperature could be controlled not only by operational parameters such as gas flow rate, voltage, frequency, but also by geometrical parameters such as electrode position. The plasma radius was up to 5.5 mm at the dielectric surface and up to 8 mm in length. The rotational temperature was varied between 310 K and 490 K. In the case of the single pin electrode only, a needle-shaped jet plasma was generated of which length was as long as 60 mm. The plasma size was varied as the operational parameters were changed. The measured gas temperature was less than 310 K under all experimental conditions. Due to the advantageous features of the plasmas, they can be applied to treat small area, thermally sensitive surfaces.

  1. Atmospheric Pressure Glow Discharge for Point-of-Use Water Treatment

    Science.gov (United States)

    Lindsay, Alexander; Byrns, Brandon; Shannon, Steven; Knappe, Detlef

    2012-10-01

    Treatment of biological and chemical contaminants is an area of growing global interest where atmospheric pressure plasmas can make a significant contribution. Addressing key challenges of volume processing and operational cost, a large volume 162 MHz coaxial air-plasma source has been developed.footnotetextByrns (2012) J. Phys. D: Appl. Phys. 45 (2012) 195204 Because of VHF ballasting effects, the electric discharge is maintained at a steady glow, allowing formation of critical non-equilibrium chemistry. High densities, ne = 10^11-10^12, have been recorded. The atmospheric nature of the device permits straightforward and efficient treatment of water samples. [H^+] concentrations in 150 milliliter tap water samples have been shown to increase by 10^5 after five minutes of discharge exposure. Recent literature has demonstrated that increasing acidity is strongly correlated with a solution's ability to deactivate microbial contaminants.footnotetextTraylor (2011) J. Phys. D: Appl. Phys. 44 (2011) 472001 The work presented here will explore the impact of treatment gas, system configuration, and power density on water disinfection and PFC abatement. An array of plasma diagnostics, including OES and electrical measurements, are combined with post-process water analysis, including GC-MS and QT analysis of coliform and E.coli bacteria. Development of volume processing atmospheric plasma disinfection methods offers promise for point-of-use treatments in developing areas of the world, potentially supplementing or replacing supply and weather-dependent disinfection methods.

  2. Crednerite-CuMnO{sub 2} thin films prepared using atmospheric pressure plasma annealing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong-Ying, E-mail: hychen@cc.kuas.edu.tw [Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, 415 Chiken Kuang Road, Kaohsiung 807, Taiwan, ROC (China); Lin, Yu-Chang [Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, 415 Chiken Kuang Road, Kaohsiung 807, Taiwan, ROC (China); Lee, Jiann-Shing [Department of Applied Physics, National Pingtung University, 4-18 Minsheng Road, Pingtung City 900, Taiwan, ROC (China)

    2015-05-30

    Highlights: • Crednerite-CuMnO{sub 2} thin films were formed at atmospheric pressure plasma with N{sub 2}–(5–10)%O{sub 2}. • The binding energy of Cu-2p spectrum of the crednerite-CuMnO{sub 2} thin films was 932.3 eV (Cu{sup +}). • The binding energies of Mn-3p spectrum were 48.1 ± 0.2 eV (Mn{sup 3+}) and 50.0 ± 0.2 eV (Mn{sup 4+}). • The cation distribution in the crednerite-CuMnO{sub 2} thin films was Cu{sub 1.0}{sup +}(Mn{sub 0.6}{sup 3+}Mn{sub 0.4}{sup 4+})O{sub 2}. • The electrical conductivity of CuMnO{sub 2} thin films was (2.61–2.65) × 10{sup 4} Ω cm. - Abstract: This study reports the preparation of crednerite-CuMnO{sub 2} thin films using atmospheric pressure plasma annealing. The pristine thin films were deposited onto a quartz substrate using the sol–gel process. The specimens were then annealed using atmospheric pressure plasma at N{sub 2}–(0–20%)O{sub 2} for 20 min. Crednerite-CuMnO{sub 2} thin films were obtained using atmospheric pressure plasma annealing at N{sub 2}–5%O{sub 2} and N{sub 2}–10%O{sub 2}. The lattice parameters of the thin films were a = 0.5574–0.5580 nm, b = 0.2874–0.2879 nm, c = 0.5878–0.5881 nm, and β = 104.15–104.25°, which agree well with previous reports. The Raman shifts of the crednerite-CuMnO{sub 2} thin films were 688 ± 2 cm{sup −1}, 381 ± 2 cm{sup −1}, and 314 ± 2 cm{sup −1}. The binding energy of Cu-2p spectrum of the crednerite-CuMnO{sub 2} thin films was 932.3 ± 0.2 eV representing the Cu{sup +} in the thin films. The binding energies of Mn-3p spectrum were 48.1 ± 0.2 eV (Mn{sup 3+}) and 50.0 ± 0.2 eV (Mn{sup 4+}). Furthermore, the cation distribution in the thin films was Cu{sup +}{sub 1.0}(Mn{sup 3+}{sub 0.6}Mn{sup 4+}{sub 0.4})O{sub 2} from the X-ray photoelectron spectroscopy measurement. When the crednerite-CuMnO{sub 2} phase was formed, the surface morphology exhibited a compact/dense granular morphology. The optical bandgap of the crednerite-CuMnO{sub 2} thin

  3. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    Directory of Open Access Journals (Sweden)

    A. M. Makarieva

    2013-01-01

    Full Text Available Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 °C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the global mean power at which this potential energy is released by condensation is around one per cent of the global solar power – this is similar to the known stationary dissipative power of general atmospheric circulation. We conclude that condensation and evaporation merit attention as major, if previously overlooked, factors in driving atmospheric dynamics.

  4. Mechanisms of sustaining a radio-frequency atmospheric pressure planar discharge

    Science.gov (United States)

    Wang, Lei; Dinescu, Gheorghe; Deng, Xiaolong; Ionita, Eusebiu-Rosini; Leys, Christophe; Nikiforov, Anton Yu

    2017-07-01

    The time behavior of an atmospheric pressure planar discharge sustained in He gas was investigated experimentally and through two dimensional (2D) discharge simulation. The 30 mm long uniform α-mode discharge was observed at radio frequency (RF) input power below 35 W. The gas temperature of 375 ± 50 K in the discharge core was estimated by emission spectroscopy of OH(A-X) emission. A sheath region of about 100-150 μm width near both electrodes was observed during the whole RF cycle. However, there were differences in emission dynamics among various species detected in the discharge. OH(A) emission does not follow the RF voltage temporal variation. Strong He emission was always detected near the cathode, which was consistent with the 2D discharge simulation results. He-excited species production was found mainly due to the electron impact process. The simulation showed that both the electron and ion density vary from 1.88 × 1017 m-3 to 1.92 × 1017 m-3, and the electron temperature was about 1.85 eV in the plasma bulk. The ion temperature stayed close to the rotational temperature of OH radicals, and only increased near the sheath region to 0.65 eV. It was found that the mechanism of the sheath formation in atmospheric pressure discharge strongly correlates with the dynamics of the electron density and electron temperature variation in the gap, and the process is similar to low pressure RF capacitively coupled discharges. The high uniformity of the discharge and the upscale possibility to any desirable size are considered beneficial for industrial applications of the source, which is key for processes of thin coating deposition and polymer modification.

  5. The critical assessment of vapour pressure estimation methods for use in modelling the formation of atmospheric organic aerosol

    Directory of Open Access Journals (Sweden)

    M. H. Barley

    2010-01-01

    Full Text Available A selection of models for estimating vapour pressures have been tested against experimental data for a set of compounds selected for their particular relevance to the formation of atmospheric aerosol by gas-liquid partitioning. The experimental vapour pressure data (all <100 Pa of 45 multifunctional compounds provide a stringent test of the estimation techniques, with a recent complex group contribution method providing the best overall results. The effect of errors in vapour pressures upon the formation of organic aerosol by gas-liquid partitioning in an atmospherically relevant example is also investigated. The mass of organic aerosol formed under typical atmospheric conditions was found to be very sensitive to the variation in vapour pressure values typically present when comparing estimation methods.

  6. Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Desmazières, Bernard [Global Bioenergies, 5 rue Henri Desbruyeres, 91030 Evry (France); Legros, Véronique [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France); Giuliani, Alexandre [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette (France); UAR1008, CEPIA, INRA, Rue de la Geraudiere, F-44316 Nantes (France); Buchmann, William, E-mail: william.buchmann@univ-evry.fr [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France)

    2014-01-15

    Graphical abstract: Atmospheric pressure photoIonization mass spectra of synthetic oligomers were recorded in the negative mode by varying the photon energy using synchrotron radiation. Photon energy required for an efficient ionization of the polymer was correlated to ionization potential of the solvent (for example 9.4 eV for tetrahydrofuran). -- Highlights: •Atmospheric pressure photoionization was performed using synchrotron radiation. •Photoionization of oligomers in THF with 10% CH{sub 2}Cl{sub 2} produces intact [M + Cl]{sup −} ions. •The photon energy required corresponds to ionization potential of the solvent. •Polymer distributions depend on source parameters such T °C and applied voltages. •Liquid chromatography was coupled to MS using an APPI interface for polymer analysis. -- Abstract: Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8 eV up to 10.6 eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the

  7. Nanosecond pulsed laser nanostructuring of Au thin films: Comparison between irradiation at low and atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Aké, C., E-mail: citlali.sanchez@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, C. U., Delegación Coyoacán, C.P. 04510, México D.F. (Mexico); Canales-Ramos, A. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, C. U., Delegación Coyoacán, C.P. 04510, México D.F. (Mexico); García-Fernández, T. [Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, Col. San Lorenzo Tezonco, México D.F., C.P. 09790 (Mexico); Villagrán-Muniz, M. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, C. U., Delegación Coyoacán, C.P. 04510, México D.F. (Mexico)

    2017-05-01

    Highlights: • Background pressure plays an important role in NPs formation and its characteristics. • The NPs diameter and their size dispersion are smaller when irradiating in vacuum. • The plasmon resonance shifts ∼15 nm to higher frequencies when irradiating in vacuum. • Film partial ablation cannot be neglected for thickness in the range 40–80 nm. • In situ optical techniques monitor the timescale of the process and ablation dynamics. - Abstract: Au thin films with tens of nm in thickness deposited on glass substrates were irradiated with nanosecond UV (355 nm) laser pulses at atmospheric pressure and in vacuum conditions (∼600 and 10{sup −5} Torr). We studied the effect of the laser fluence (200–400 mJ/cm{sup 2}), thickness of the starting film (∼40–80 nm) and surrounding pressure on the partial ablation/evaporation of the films and the morphology of the produced nanoparticles (NPs). The dynamics of NPs formation was studied by measuring in real time the transmission of the samples upon continuous-wave laser exposure, and by means of probe beam deflection technique. The ejection of material from the film as a result of the irradiation was confirmed by time-resolved shadowgraphy technique. Experiments show that the NPs diameter and their size distribution are smaller when the irradiation is performed in vacuum regardless the laser fluence and thickness of the started film. It is also shown that the plasmon band shifts to higher frequencies with lower background pressure. The optical measurements show that the films melt and ablate during the laser pulse, but the transmission of the irradiated areas continues changing during tens of microseconds due to ejection of material and solidification of the remaining gold. Our results indicate that partial ablation cannot be neglected in nanostructuration by ns-pulsed irradiation of thin films when their thickness is in the studied range.

  8. Application of atmospheric pressure plasma on polyethylene for increased prosthesis adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Van Vrekhem, S., E-mail: stijn.vanvrekhem@ugent.be [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Cools, P. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Declercq, H. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Tissue Engineering Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 6B3, 9000 Ghent (Belgium); Van Tongel, A. [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185 13K12, 9000 Ghent (Belgium); Vercruysse, C.; Cornelissen, M. [Tissue Engineering Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 6B3, 9000 Ghent (Belgium); De Geyter, N.; Morent, R. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium)

    2015-12-01

    Biopolymers are often subjected to surface modification in order to improve their surface characteristics. The goal of this study is to show the use of plasma technology to enhance the adhesion of ultra-high molecular weight polyethylene (UHMWPE) shoulder prostheses. Two different plasma techniques (low pressure plasma activation and atmospheric pressure plasma polymerization) are performed on UHMWPE to increase the adhesion between (1) the polymer and polymethylmethacrylate (PMMA) bone cement and (2) the polymer and osteoblast cells. Both techniques are performed using a dielectric barrier discharge (DBD). A previous paper showed that low pressure plasma activation of UHMWPE results in the incorporation of oxygen-containing functional groups, which leads to an increased surface wettability. Atmospheric pressure plasma polymerization of methylmethacrylate (MMA) on UHMWPE results in a PMMA-like coating, which could be deposited with a high degree of control of chemical composition and layer thickness. The thin film also proved to be relatively stable upon incubation in a phosphate buffer solution (PBS). This paper discusses the next stage of the study, which includes testing the adhesion of the plasma-activated and plasma-polymerized samples to bone cement through pull-out tests and testing the cell adhesion and proliferation on the samples. In order to perform the pull-out tests, all samples were cut to standard dimensions and fixed in bone cement in a reproducible way with a sample holder specially designed for this purpose. The cell adhesion and proliferation were tested by means of an MTS assay and live/dead staining after culturing MC3T3 osteoblast cells on UHMWPE samples. The results show that both plasma activation and plasma polymerization significantly improve the adhesion to bone cement and enhance cell adhesion and proliferation. In conclusion, it can be stated that the use of plasma technology can lead to an implant with improved quality and a subsequent

  9. Atmospheric-pressure plasma jet system for silicon etching without fluorocarbon gas feed

    Science.gov (United States)

    Ohtsu, Yasunori; Nagamatsu, Kenta

    2018-01-01

    We developed an atmospheric-pressure plasma jet (APPJ) system with a tungsten rod electrode coated with C2F4 particles of approximately 0.3 µm diameter for the surface treatment of a silicon wafer. The APPJ was generated by dielectric barrier discharge with a driving frequency of 22 kHz using a He gas flow. The characteristics of the APPJ were examined under various experimental conditions. The plasma jet length increased proportionally to the electric field. It was found that the treatment area of the silicon wafer was approximately 1 mm in diameter. By atomic force microscopy analysis, minute irregularities with a maximum length of about 600 nm and part of a ring-shaped trench were observed. A Si etching rate of approximately 400 nm/min was attained at a low power of 6 W and a He flow rate of 1 L/min without introducing molecular gas including F atoms.

  10. Monte Carlo analysis of field-dependent electron avalanche coefficients in nitrogen at atmospheric pressure

    Science.gov (United States)

    Nguyen, H. K.; Mankowski, J.; Dickens, J. C.; Neuber, A. A.; Joshi, R. P.

    2017-12-01

    Calculations of electron impact ionization of nitrogen gas at atmospheric pressure are presented based on the kinetic Monte Carlo technique. The emphasis is on energy partitioning between primary and secondary electrons, and three different energy sharing schemes have been evaluated. The ionization behavior is based on Wannier's classical treatment. Our Monte Carlo results for the field-dependent drift velocities match the available experimental data. More interestingly, the field-dependent first Townsend coefficient predicted by the Monte Carlo calculations is shown to be in close agreement with reported data for E/N values ranging as high as 4000 Td, only when a random assignment of excess energies between the primary and secondary particles is used.

  11. Statistical modelling of discharge behavior of atmospheric pressure dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Tay, W. H.; Kausik, S. S.; Wong, C. S., E-mail: cswong@um.edu.my; Yap, S. L.; Muniandy, S. V. [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-11-15

    In this work, stochastic behavior of atmospheric pressure dielectric barrier discharge (DBD) has been investigated. The experiment is performed in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes powered by a 50 Hz ac high voltage source. Current pulse amplitude distributions for different space gaps and the time separation between consecutive current pulses are studied. A probability distribution function is proposed to predict the experimental distribution function for the current pulse amplitudes and the occurrence of the transition regime of the pulse distribution. Breakdown voltage at different positions on the dielectric surface is suggested to be stochastic in nature. The simulated results based on the proposed distribution function agreed well with the experimental results and able to predict the regime of transition voltage. This model would be useful for the understanding of stochastic behaviors of DBD and the design of DBD device for effective operation and applications.

  12. Pressure Contact Sounding Data for NASA's Atmospheric Variability Experiment (AVE 3)

    Science.gov (United States)

    Fuelberg, H. E.; Hill, C. K.; Turner, R. E.; Long, K. E.

    1975-01-01

    The basic rawinsonde data are described at each pressure contact from the surface to sounding termination for the 41 stations participating in the AVE III measurement program that began at 0000 GMT on February 6 and ended at 1200 GMT on February 7, 1975. Soundings were taken at 3-hour intervals during a large period of the experiment from most stations within the United States east of about 105 degrees west longitude. Methods of data processing, change in reduction scheme since the AVE II pilot experiment, and data accuracy are briefly discussed. An example of contact data is presented, and microfiche cards of all the contact data are included in the appendix. The AVE III project was conducted to better understand and establish the extent of applications for meteorological satellite sensor data through correlative ground truth experiments and to provide basic experimental data for use in studies of atmospheric scales of-motion interrelationships.

  13. Pressure contact sounding data for NASA's Atmospheric Variability Experiment (AVE 2). [rawinsondes

    Science.gov (United States)

    Fuelberg, H. E.; Turner, R. E.

    1975-01-01

    The basic rawinsonde data are described at each pressure contact from the surface to sounding termination for the 54 stations participating in the AVE 2 pilot experiment. Soundings were taken at three-hour intervals from stations within the United States east of about 105 degrees west longitude. Methods of data reduction and estimates of data accuracy are discussed. Examples of the data records produced are shown. The AVE 2 pilot experiment was conducted as part of NASA's program to better understand and establish the extent of applications for meteorological satellite sensor data through correlative ground truth experiments and to provide basic experimental data for use in studies of atmospheric scales-of-motion interrelationships.

  14. A model for plasma modification of polypropylene using atmospheric pressure discharges

    CERN Document Server

    Dorai, R

    2003-01-01

    Atmospheric pressure plasmas are commonly used to improve the wetting and adhesion properties of polymers. In spite of their use, the mechanisms for achieving these properties are unclear. In this regard, we report on a computational investigation of the gas phase and surface kinetics during humid-air corona treatment of polypropylene (PP) and the resulting modification of its surface properties while varying energy deposition, relative humidity (RH), web speed, and gas temperature. Using results from a global plasma chemistry model validated against experiments, we found that increasing energy deposition increased the densities of alcohol, carbonyl, acid, and peroxy radicals on the PP surface. In doing so, significant amounts of gas phase O sub 3 and N sub x O sub y are produced. Increasing the RH increased the production of peroxy and acid groups, while decreasing those of alcohol and carbonyl groups. Production of O sub 3 decreased while that of HNO sub 3 increased. Increasing the temperature decreased the...

  15. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan

    2014-01-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating...... current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column......, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light...

  16. Atmospheric-pressure plasma jet characterization and applications on melanoma cancer treatment (B/16-F10)

    Energy Technology Data Exchange (ETDEWEB)

    Mashayekh, Shahriar [Physics Department, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Rajaee, Hajar; Hassan, Zuhir M. [Imonology Department, Faculty of Medical Science, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Akhlaghi, Morteza [Laser-Plasma Research Institute, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Shokri, Babak [Physics Department and Laser-Plasma Research Institute, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Islamic Republic of Iran (Iran, Islamic Republic of)

    2015-09-15

    A new approach in medicine is the use of cold plasma for various applications such as sterilization blood coagulation and cancer cell treatment. In this paper, a pin-to-hole plasma jet for biological applications has been designed and manufactured and characterized. The characterization includes power consumption via Lissajous method, thermal behavior of atmospheric-pressure plasma jet by using Infra-red camera as a novel method and using Speicair software to determine vibrational and transitional temperatures, and optical emission spectroscopy to determine the generated species. Treatment of Melanoma cancer cells (B16/F10) was also implemented, and tetrazolium salt dye (MTT assay) and flow cytometry were used to evaluate viability. Effect of ultraviolet photons on cancerous cells was also observed using an MgF{sub 2} crystal with MTT assay. Finally, in-vivo studies on C57 type mice were also done in order to have a better understanding of the effects in real conditions.

  17. The use of atmospheric pressure plasma as a curing process for canned ground ham.

    Science.gov (United States)

    Lee, Juri; Jo, Kyung; Lim, Yubong; Jeon, Hee Joon; Choe, Jun Ho; Jo, Cheorun; Jung, Samooel

    2018-02-01

    This study investigated the potential use of atmospheric pressure plasma (APP) treatment as a curing process for canned ground ham. APP treatment for 60min while mixing increased the nitrite content in the meat batters from 0.64 to 60.50mgkg(-1) while the pH and the total content of aerobic bacteria in the meat batters were unchanged. The canned ground hams cured by the APP treatment for 30min displayed no difference in their physicochemical qualities, such as nitrosyl hemochrome, color, residual nitrite, texture, lipid oxidation, and protein oxidation, compared with those of canned ground hams cured with sodium nitrite or celery powder at 42mgkg(-1) of nitrite. The canned ground hams cured by the APP treatment received a higher score in taste and overall acceptability than those cured with sodium nitrite. Canned ground ham can be cured by the APP treatment without nitrite additives. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    Science.gov (United States)

    Yaopromsiri, C.; Yu, L. D.; Sarapirom, S.; Thopan, P.; Boonyawan, D.

    2015-12-01

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  19. Generation and characterization of OH and O radicals by atmospheric pressure steam/oxygen plasma

    CERN Document Server

    Roy, N C; Alam, M K; Talukder, M R

    2016-01-01

    Atmospheric pressure steam/oxygen plasma is generated by a 88 Hz, 6kV AC power supply. The properties of the produced plasma are investigated by optical emission spectroscopy (OES). The relative intensity, rotational, vibrational, excitation temperatures and electron density are studied as function of applied voltage, electrode spacing and oxygen flow rate. The rotational and vibrational temperatures are determined simulating the bands with the aid of LIFBASE simulation software. The excitation temperature is obtained from the CuI transition taking non-thermal equilibrium condition into account employing intensity ratio method. The electron density is approximated from the H_{\\alpha} Stark broadening using the Voigt profile fitting method. It is observed that the rotational and vibrational temperatures are decreased with increasing electrode spacing and O2 flow rate, but increased with the applied voltage. The excitation temperature is found to increase with increasing applied voltage and O2 flow rate, but de...

  20. Synthesis of Carbon Nanotubes in Thermal Plasma Reactor at Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Lukasz Szymanski

    2017-02-01

    Full Text Available In this paper, a novel approach to the synthesis of the carbon nanotubes (CNTs in reactors operating at atmospheric pressure is presented. Based on the literature and our own research results, the most effective methods of CNT synthesis are investigated. Then, careful selection of reagents for the synthesis process is shown. Thanks to the performed calculations, an optimum composition of gases and the temperature for successful CNT synthesis in the CVD (chemical vapor deposition process can be chosen. The results, having practical significance, may lead to an improvement of nanomaterials synthesis technology. The study can be used to produce CNTs for electrical and electronic equipment (i.e., supercapacitors or cooling radiators. There is also a possibility of using them in medicine for cancer diagnostics and therapy.

  1. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    Science.gov (United States)

    Carr,; Jeffrey, W [Livermore, CA

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  2. Development of a scanning nanopipette probe microscope for fine processing using atmospheric pressure plasma jet

    Science.gov (United States)

    Morimatsu, Daisuke; Sugimoto, Hiromitsu; Nakamura, Atsushi; Ogino, Akihisa; Nagatsu, Masaaki; Iwata, Futoshi

    2016-08-01

    We developed a novel technique for fine material processing based on a localized atmospheric-pressure plasma jet (APPJ) using a scanning probe microscope equipped with a nanopipette. Using a nanopipette — a tapered glass capillary with an aperture of sub-micrometer diameter — as a nozzle makes it possible to localize the discharge area of the APPJ for fine surface processing. The nanopipette can also be used as a probe for a scanning probe microscope operated with shear-force feedback control, which is capable of positioning the pipette edge in the vicinity of material surfaces for APPJ processing and imaging of the processed surface. Sub-micrometer holes and line patterns were successfully processed on a photoresist film. It was possible to control the size of the processed patterns by varying the applied pulse voltage and the distance between the pipette and the surface.

  3. Independent Orbiter Assessment (IOA): Assessment of the atmospheric revitalization pressure control subsystem FMEA/CIL

    Science.gov (United States)

    Saiidi, M. J.

    1988-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the atmospheric Revitalization Pressure Control Subsystem (ARPCS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL proposed Post 51-L updates based upon the CCB/PRCB presentations and an informal criticality summary listing. A discussion of each discrepancy from the comparison is provided through additional analysis as required. These discrepancies were flagged as issues, and recommendations were made based on the FMEA data available at the time. This report documents the results of that comparison for the Orbiter ARPCS hardware.

  4. Effect of swirling desolvation gas flow in an atmospheric pressure ion source.

    Science.gov (United States)

    Savtchenko, Serguei; Ashgriz, Nasser; Jolliffe, Chuck; Cousins, Lisa; Gamble, Heather

    2014-09-01

    A numerical study is performed to examine the effect of introducing a swirling desolvation gas flow on the flow transport characteristics in an electrospray and an atmospheric pressure chemical ionization (APCI) system. An ion source having three coaxial tubes is considered: (1) an inner capillary tube to inject the liquid sample, (2) a center coaxial tube to provide a room temperature gas flow to nebulize the liquid, referred to as the nebulizing gas flow, and (3) an outer coaxial tube having a converging exit to supply a high temperature gas for droplet desolvation, referred to as the desolvation gas flow. The results show that a swirling desolvation gas flow reduces the dispersion of the nebulizing gas and suppresses turbulent diffusion. The effect of swirling desolvation flow on the trajectory of a range of droplet sizes emitted from a source is also considered.

  5. Sheath and bulk expansion induced by RF bias in atmospheric pressure microwave plasma

    Science.gov (United States)

    Lee, Jimo; Nam, Woojin; Lee, Jae Koo; Yun, Gunsu

    2017-10-01

    A large axial volume expansion of microwave-driven plasma at atmospheric pressure is achieved by applying a low power radio frequency (RF) bias at an axial location well isolated from the original plasma bulk. The evolution of the plasma plume visualized by high speed ICCD imaging suggest that the free electrons drifting toward the bias electrode cause the prodigious expansion of the sheath, creating a stable plasma stream channel between the microwave and the RF electrodes. For argon plasma in ambient air, enhanced emissions of OH and N2 spectral lines are measured in the extended plume region, supporting the acceleration of electrons and subsequent generation of radical species. The coupling of RF bias with microwave provides an efficient way of enlarging the plasma volume and enhancing the production of radicals. Work supported by the National Research Foundation of Korea under BK21+ program and Grant No. 2015R1D1A1A01061556 (Ministry of Education).

  6. Gas mixing enhanced by power modulations in atmospheric pressure microwave plasma jet

    Science.gov (United States)

    Voráč, J.; Potočňáková, L.; Synek, P.; Hnilica, J.; Kudrle, V.

    2016-04-01

    Microwave plasma jet operating in atmospheric pressure argon was power modulated by audio frequency sine envelope in the 102 W power range. Its effluent was imaged using interference filters and ICCD camera for several different phases of the modulating signal. The combination of this fast imaging with spatially resolved optical emission spectroscopy provides useful insights into the plasmachemical processes involved. Phase-resolved schlieren photography was performed to visualize the gas dynamics. The results show that for higher modulation frequencies the plasma chemistry is strongly influenced by formation of transient flow perturbation resembling a vortex during each period. The perturbation formation and speed are strongly influenced by the frequency and power variations while they depend only weakly on the working gas flow rate. From application point of view, the perturbation presence significantly broadened lateral distribution of active species, effectively increasing cross-sectional area suitable for applications.

  7. Surface modification of nanofibrillated cellulose films by atmospheric pressure dielectric barrier discharge

    DEFF Research Database (Denmark)

    Siró, Istvan; Kusano, Yukihiro; Norrman, Kion

    2013-01-01

    of atmospheric pressure plasma treatment, the water contact angle of NFC films increased and the values were comparable with those of PLA films. On the other hand, surface chemical characterization revealed inhomogeneity of the plasma treatment and limited improvement in adhesion between NFC and PLA films......A dielectric barrier discharge in a gas mixture of tetrafluoromethane (CF4) and O2 was used for tailoring the surface properties of nanofibrillated cellulose (NFC) films. The surface chemical composition of plasma-modified NFC was characterized by means of X-ray photoelectron spectroscopy and time......-of-flight secondary ion mass spectrometry, while surface morphology was illustrated by atomic force microscopy. Wettability was characterized through the static sessile drop method. The adhesion between NFC and polylactide (PLA) laminated films was tested by the double cantilever beam technique. As a result...

  8. Plasma chemistry in an atmospheric pressure Ar/NH3 dielectric barrier discharge

    DEFF Research Database (Denmark)

    Fateev, A.; Leipold, F.; Kusano, Y.

    2005-01-01

    absorption spectroscopy was also employed for the detection of stable products in the exhaust gas. To clarify the different processes for ammonia decomposition, N-2(2 - 10%) was added to the plasma. Modeling of the chemical kinetics in an Ar/NH3 plasma was performed as well. The dominant stable products...... of an atmospheric pressure Ar/NH3 DBD are H-2, N-2 and N2H4. The hydrazine (N2H4) concentration in the plasma and in the exhaust gases at various ammonia concentrations and different discharge powers was measured. Thermal N2H4 decomposition into NH2 radicals may be used for NOx reduction processes....

  9. Sterilisation of Hydroponic Culture Solution Contaminated by Fungi using an Atmospheric Pressure Corona Discharge

    Science.gov (United States)

    Mizukami, Kohji; Satoh, Kohki; Kanayama, Hiroshi; Itoh, Hidenori; Tagashira, Hiroaki; Shimozuma, Mitsuo; Okamoto, Hiroyuki; Takasaki, Satoko; Kinoshita, Muneshige

    The hydroponic culture solution contaminated by fungi is sterilised by a DC corona discharge, and the sterilisation characteristics are investigated in this work. A DC streamer corona discharge is generated at atmospheric pressure in air between needle clusters and a water bath containing contaminated solution by fungus such as Fusarium oxysporum f. sp. spinaciae or Fusarium sp.. It is found that the fungi are killed by the exposure of the corona discharge, and that the death rates of the fungi chiefly depend on the concentration of the hydroponic culture solutions. It is also found that the number densities of the fungi decrease exponentially with the energy expenditure of the corona discharge, and that damping coefficients of the fungi densities depend on the concentration of the hydroponic culture solutions. This suggests that the fungi are chiefly inactivated by electroporation.

  10. A battery-operated atmospheric-pressure plasma wand for biomedical applications

    Science.gov (United States)

    Pei, X.; Liu, J.; Xian, Y.; Lu, X.

    2014-04-01

    A handheld, battery-operated atmospheric-pressure plasma rod (named the plasma wand) which does not rely on an external power source (e.g. mains power or a power generator) or gas supply is reported. The plasma wand can be used for killing bacteria, fungi or viruses that are hidden in narrow channels such as the nasal cavity and ear canal, which are difficult to access using most currently available devices. Besides, the electrical characterization, plasma wand temperature, emission spectra of the plasma, ozone and OH radical concentration generated by the device, are investigated by different diagnostic methods. The ozone concentration reaches 120 ppm 1 mm away from the device and the OH concentration reaches 3.5 × 1014 cm-3 in the plasma. The preliminary bacteria inactivation experiment results show that all the bacteria samples on the microfiltration membrane are killed by this device within 30 s.

  11. The gas conversion of methane with oxygen at atmospheric pressure using a cylindrical dielectric barrier discharge

    Science.gov (United States)

    Martens, Tom; Petrovic, Dragana; de Bie, Christophe; Bogaerts, Annemie; Brok, Wouter; van Dijk, Jan

    2008-10-01

    The conversion of methane to useful chemicals and liquid fuels currently requires steam reforming, which requires great amounts of energy input. We are currently investigating the possibilities of using a plasma activated system for this gas conversion. Due to the pulsed nature and the low operating temperature capabilities, we have chosen the atmospheric pressure dielectric barrier discharge as a setup to investigate whether it can be used as a more efficient gas conversion reactor. For this purpose we have developed a CH4/O2 chemical reaction set and used it in a 2D fluid model of a cylindrical dielectric barrier discharge, in which we also incorporate the influence of the gas flow. In this way we investigate whether we can optimize the production of methanol or formaldehyde. The parameters under study are the CH4/O2 ratio, the applied voltage characteristics, the gap width and the gas flow rate.

  12. Controlled growth of copper oxide nanostructures by atmospheric pressure micro-afterglow

    Science.gov (United States)

    Altaweel, A.; Filipič, G.; Gries, T.; Belmonte, T.

    2014-12-01

    A large variety of copper oxide nanostructures encompassing nanodots, nanowires and nanowalls, sometimes organized in ;cabbage-like; architectures, are grown locally by direct oxidation of copper thin films using the micro-afterglow of an Ar-O2 microwave plasma operating at atmospheric pressure. Morphology, structure and composition of the oxidized copper thin films are characterized by X-ray diffraction, secondary ion mass spectrometry and scanning electron microscopy. The concentric areas where each kind of nanostructures is found are defined by both their radial position with respect to the afterglow centre and by experimental conditions. A growth mechanism is proposed, based on stress-induced outward migration of copper ions. The development of stress gradients is caused by the formation of a copper oxide scale layer. If copper oxide nanowires can be grown as in thermal oxidation processes, micro-afterglow conditions offer novel nanostructures and nano-architectures.

  13. Atmospheric pressure plasma treatment of glass fibre composite for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, H.; Stenum, Bjarne

    2007-01-01

    treated for more than 30 s. X-Ray photoelectron spectroscopic analysis showed that the contents of aluminium and oxygen on the surface increased with the plasma treatment. The adhesion strength of the 2-s treated surface was comparable to or higher than that achieved by conventional mechanical surface......Glass-fibre-reinforced polyester composite plates were treated with an atmospheric pressure dielectric barrier discharge. Synthetic air was used as the treatment gas. The water contact angle dropped markedly from 84 to 22° after a 2-s treatment, and decreased to 0° when the composite plates were...... roughening. It decreased when the surfaces were treated for 5 and 15 s, but recovered for 30-s treatment....

  14. Sterilization Efficiency of Spore forming Bacteria in Powdery Food by Atmospheric Pressure Plasmas Sterilizer

    Science.gov (United States)

    Nagata, Masayoshi; Tanaka, Masashi; Kikuchi, Yusuke

    2015-09-01

    To provide food sterilization method capable of killing highly heat resistant spore forming bacteria, we have studied effects of plasma treatment method at atmospheric pressure in order to develop a new high speed plasma sterilization apparatus with a low cost and a high efficiency. It is also difficult even for the plasma treatment to sterilize powdery food including spices such as soybean, basil and turmeric. This paper describes that an introduction of mechanical rotation of a treatment space increases the efficiency so that perfect inactivation of spore forming bacteria in these materials by a short treatment time has been demonstrated in our experiments. We also will discuss the sterilization mechanism by dielectric barrier discharge.

  15. Atmospheric-pressure glow plasma synthesis of plasmonic and photoluminescent zinc oxide nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Bilik, N., E-mail: bilik006@umn.edu, E-mail: kortshagen@umn.edu; Greenberg, B. L.; Yang, J.; Kortshagen, U. R., E-mail: bilik006@umn.edu, E-mail: kortshagen@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Aydil, E. S. [Department of Chemical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2016-06-28

    In this paper, we present a large-volume (non-micro) atmospheric pressure glow plasma capable of rapid, large-scale zinc oxide nanocrystal synthesis and deposition (up to 400 μg/min), whereas in the majority of the literature, nanoparticles are synthesized using micro-scale or filamentary plasmas. The reactor is an RF dielectric barrier discharge with a non-uniform gap spacing. This design encourages pre-ionization during the plasma breakdown, making the discharge uniform over a large volume. The produced zinc oxide nanocrystals typically have diameters ranging from 4 to 15 nm and exhibit photoluminescence at ≈550 nm and localized surface plasmon resonance at ≈1900 cm{sup −1} due to oxygen vacancies. The particle size can be tuned to a degree by varying the gas temperature and the precursor mixing ratio.

  16. CO2 sensing at atmospheric pressure using fiber Fabry-Perot interferometer

    Science.gov (United States)

    Ma, Wenwen; He, Yelu; Zhao, Yangfan; Shen, Shilei; Wang, Ruohui; Qiao, Xueguang

    2017-05-01

    A Fabry-Perot interferometer (FPI) for CO2 gas sensing at atmospheric pressure is proposed and experimentally demonstrated. The gas sensing material is poly(ethyleneimine) (PEI)/poly(vinylalcohol) (PVA) compound, which exhibits reversible refrative index change upon absorption and release of CO2 gas molecules. The FPI is fabricated by coating a PEI/P VA film with a thickness of 15μm film at the end face of a single-mode fiber (SMF). A well-confined interference spectrum with fringe contrast of 19.5 dB and free spectra range (FSR) of 33.15 nm is obtained. The proposed FPI sensor is sensitive to the CO2 gas concentration change, and a sensitivity of 0.2833nm/PCT is obtained. The FPI sensor provides a solution in the development of low-cost and compact gas sensors for CO2 leakage monitoring.

  17. Translation Effects in Fluorine Doped Tin Oxide Thin Film Properties by Atmospheric Pressure Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Mohammad Afzaal

    2016-10-01

    Full Text Available In this work, the impact of translation rates in fluorine doped tin oxide (FTO thin films using atmospheric pressure chemical vapour deposition (APCVD were studied. We demonstrated that by adjusting the translation speeds of the susceptor, the growth rates of the FTO films varied and hence many of the film properties were modified. X-ray powder diffraction showed an increased preferred orientation along the (200 plane at higher translation rates, although with no actual change in the particle sizes. A reduction in dopant level resulted in decreased particle sizes and a much greater degree of (200 preferred orientation. For low dopant concentration levels, atomic force microscope (AFM studies showed a reduction in roughness (and lower optical haze with increased translation rate and decreased growth rates. Electrical measurements concluded that the resistivity, carrier concentration, and mobility of films were dependent on the level of fluorine dopant, the translation rate and hence the growth rates of the deposited films.

  18. Spatiotemporally resolved characteristics of a gliding arc discharge in a turbulent air flow at atmospheric pressure

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2017-01-01

    of the glow-type discharge is the same as that of the electronic power dissipated in the plasma column. The glow-type discharge can transfer into a spark discharge characterized by a sharp peak current of several amperes and a sudden increase of the brightness in the plasma column. Transitions can also......A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by a 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the gliding arc discharge, including glow-type discharges, spark-type discharges, short-cutting events...... be found to take place from spark-type discharges to glow-type discharges. Short-cutting events were often observed as the intermediate states formed during the spark-glow transition. Three different types of short-cutting events have been observed to generate new current paths between two plasma channel...

  19. Cold atmospheric pressure plasma for treatment of chronic wounds: drug or medical device?

    Science.gov (United States)

    Kramer, A; Conway, B R; Meissner, K; Scholz, F; Rauch, B H; Moroder, A; Ehlers, A; Meixner, A J; Heidecke, C-D; Partecke, L I; Kietzmann, M; Assadian, O

    2017-08-02

    The use of cold atmospheric pressure plasma (CAPP) as a new therapeutic option to aid the healing of chronic wounds appears promising. Currently, uncertainty exists regarding their classification as medical device or medical drug. Because the classification of CAPP has medical, legal, and economic consequences as well as implications for the level of preclinical and clinical testing, the correct classification is not an academic exercise, but an ethical need. A multidisciplinary team of physicians, surgeons, pharmacists, physicists and lawyers has analysed the physical and technical characteristics as well as legal conditions of the biological action of CAPP. It was concluded that the mode of action of the locally generated CAPP, with its main active components being different radicals, is pharmacological and not physical in nature. Depending on the intended use, CAPP should be classified as a drug, which is generated by use of a medical device directly at the point of therapeutic application.

  20. Electron heating and mode transition in dual frequency atmospheric pressure argon dielectric barrier discharge

    Science.gov (United States)

    Zhang, Z. L.; Lim, J. W. M.; Nie, Q. Y.; Zhang, X. N.; Jiang, B. H.

    2017-10-01

    Plasma ionization, excitation, mode transitions and associated electron heating mechanisms in atmospheric pressure dielectric barrier discharges (DBD) driven by dual radio frequency sources are investigated in this paper. The electrons are found to be heated mainly by the high frequency component in the plasma bulk when discharged in α mode. On the contrary, the low frequency component is primarily responsible for heating in the sheath which is caused by intense motion in the sheath. It was also found that variation of the lower frequency component ratio could effectively modulate the electron energy distribution as determined from time averaged EEDF. The results above have demonstrated that the independent control of plasma parameters via non-linear synergistic effect between the dual frequency sources can be achieved through reasonable selection of processing parameters.

  1. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    Energy Technology Data Exchange (ETDEWEB)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O' Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  2. Established and emerging atmospheric pressure surface sampling/ionization techniques for mass spectrometry.

    Science.gov (United States)

    Van Berkel, Gary J; Pasilis, Sofie P; Ovchinnikova, Olga

    2008-09-01

    The number and type of atmospheric pressure techniques suitable for sampling analytes from surfaces, forming ions from these analytes, and subsequently transporting these ions into vacuum for interrogation by MS have rapidly expanded over the last several years. Moreover, the literature in this area is complicated by an explosion in acronyms for these techniques, many of which provide no information relating to the chemical or physical processes involved. In this tutorial article, we sort this vast array of techniques into relatively few categories on the basis of the approaches used for surface sampling and ionization. For each technique, we explain, as best known, many of the underlying principles of operation, describe representative applications, and in some cases, discuss needed research or advancements and attempt to forecast their future analytical utility.

  3. Synthesis of Carbon Nanotubes in Thermal Plasma Reactor at Atmospheric Pressure.

    Science.gov (United States)

    Szymanski, Lukasz; Kolacinski, Zbigniew; Wiak, Slawomir; Raniszewski, Grzegorz; Pietrzak, Lukasz

    2017-02-18

    In this paper, a novel approach to the synthesis of the carbon nanotubes (CNTs) in reactors operating at atmospheric pressure is presented. Based on the literature and our own research results, the most effective methods of CNT synthesis are investigated. Then, careful selection of reagents for the synthesis process is shown. Thanks to the performed calculations, an optimum composition of gases and the temperature for successful CNT synthesis in the CVD (chemical vapor deposition) process can be chosen. The results, having practical significance, may lead to an improvement of nanomaterials synthesis technology. The study can be used to produce CNTs for electrical and electronic equipment (i.e., supercapacitors or cooling radiators). There is also a possibility of using them in medicine for cancer diagnostics and therapy.

  4. The transfer of atmospheric-pressure ionization waves via a metal wire

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yang; Liu, Dongping, E-mail: Dongping.liu@dlnu.edu.cn [Liaoning Key Lab of Optoelectronic Films & Materials, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Wang, Wenchun [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Peng, Yifeng; Niu, Jinhai; Bi, Zhenhua; Ji, Longfei; Song, Ying; Wang, Xueyang; Qi, Zhihua [Liaoning Key Lab of Optoelectronic Films & Materials, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China)

    2016-01-15

    Our study has shown that the atmospheric-pressure He ionization waves (IWs) may be transferred from one dielectric tube (tube 1) to the other one (tube 2) via a floating metal wire. The propagation of IWs along the two tubes is not affected by the diameter of a floating metal wire, however, their propagation is strongly dependent on the length of a floating metal wire. The propagation of one IW along the tube 1 may result in the second IW propagating reversely inside the tube in vicinity of a floating metal wire, which keeps from their further propagation through the tube 1. After they merge together as one conduction channel inside the tube 1, the transferred plasma bullet starts to propagate along the tube 2. The propagation of transferred plasma bullets along the tube 2 is mainly determined by the capacitance and inductance effects, and their velocity and density can be controlled by the length of a floating metal wire.

  5. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    Energy Technology Data Exchange (ETDEWEB)

    Yaopromsiri, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Bang Khen, Chiang Mai 50290 (Thailand); Thopan, P.; Boonyawan, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-12-15

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  6. Effect of non-thermal atmospheric pressure plasma jet on human breast cancer cells

    Science.gov (United States)

    Mirpour, Shahriar; Nikkhah, Maryam; Pirouzmand, Somaye; Ghomi, Hamid Reza

    2012-10-01

    Nowadays, Non-thermal plasma enjoy a wide range of applications in biomedical fields such as Sterilization, Wound healing, Cancer treatment and etc. The aim of this paper is to study the effect of non-thermal atmospheric pressure plasma jet on breast cancer (MCF-7) cells. In this regard the effect of plasma on death of the cancer cells are explored experimentally. The plasma in this discharge is created by pulsed dc high voltage power supply with repetition rate of several tens of kilohertz which led to the inductively coupled plasma. The pure helium gas were used for formation of the plasma jet. MTT assay were used for quantification of death cells. The results showed that the cells death rate increase with plasma exposure time. This study confirm that plasma jet have significant effect on treatment of human breast cancer cells.

  7. Dominant Overall Chemical Reaction in a Chlorine Trifluoride Silicon Nitrogen System at Atmospheric Pressure

    Science.gov (United States)

    Habuka, Hitoshi; Otsuka, Toru; Qu, Wei-Feng

    1999-11-01

    This study evaluates the overall chemical reaction in a chlorine trifluoride silicon nitrogen system at atmospheric pressure, based on the observation of the dominant chemical species in the gas phase using a quadrupole mass spectra analyzer coupled with a horizontal cold-wall single-wafer epitaxial reactor. Chlorine trifluoride gas etches the silicon surface, producing two major products, silicon tetrafluoride gas and chlorine gas, at room temperature and 530 K. The production of chlorosilanes was not observed in this study. The results obtained in this study indicate that the dominant overall chemical reaction in a chlorine trifluoride silicon nitrogen system is 3Si + 4ClF3 →3SiF4 ↑+ 2Cl2 ↑.

  8. Control of the Proliferation of Mammalian Cells by the Non-Thermal Atmospheric Pressure Plasmas

    Science.gov (United States)

    Lee, Hae June; Ha, Chang Seung; Ma, Yonghao; Lee, Jungyeol; Song, Kiwon

    2012-10-01

    Recent development of the atmospheric pressure plasmas (APPs) reported dramatic achievement on the applications to sterilization, wound healing, blood coagulation, and so on. These effects are coming from the abundant electrons, various ions, radicals, and neutral atoms which cause specific interactions with cells. However, the application of APPs to human cells has been mainly focused on cell death, but not so much on cell proliferation. In this study, the effects of a non-thermal dielectric barrier discharge (DBD) were investigated for three different human cell lines. It was observed that the exposure of APP to human adipose-derived stem cells (ASC) and the primary lung fibroblast IMR-90 cells induced increased cell proliferation in a specific condition. On the other hand, the same exposure of APP to HeLa cells dramatically decreased their viability. These observations suggest that different types of human cells differentially respond to the exposure of APP.

  9. Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure

    Science.gov (United States)

    Bodik, Michal; Zahoranova, Anna; Micusik, Matej; Bugarova, Nikola; Spitalsky, Zdenko; Omastova, Maria; Majkova, Eva; Jergel, Matej; Siffalovic, Peter

    2017-04-01

    We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm-3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

  10. Atmospheric-pressure electric discharge as an instrument of chemical activation of water solutions

    Science.gov (United States)

    Rybkin, V. V.; Shutov, D. A.

    2017-11-01

    Results of experimental studies and numerical simulations of physicochemical characteristics of plasmas generated in different types of atmospheric-pressure discharges (pulsed streamer corona, gliding electric arc, dielectric barrier discharge, glow-discharge electrolysis, diaphragmatic discharge, and dc glow discharge) used to initiate various chemical processes in water solutions are analyzed. Typical reactor designs are considered. Data on the power supply characteristics, plasma electron parameters, gas temperatures, and densities of active particles in different types of discharges excited in different gases and their dependences on the external parameters of discharges are presented. The chemical composition of active particles formed in water is described. Possible mechanisms of production and loss of plasma particles are discussed.

  11. Impact of low atmosphere pressure stunning of broilers on breast skin Salmonella and Campylobacter post-defeathering and breast fillet meat quality

    Science.gov (United States)

    Low atmosphere pressure stun (LAPS) is a method of controlled atmosphere poultry slaughter that utilizes a decrease of atmospheric pressure (0.2 ATM) to induce unconsciousness and death. Following feed withdrawal periods of 4, 6, 8, or 10 hours, broilers were slaughtered using LAPS or electrical stu...

  12. Induction of proliferation of basal epidermal keratinocytes by cold atmospheric-pressure plasma.

    Science.gov (United States)

    Hasse, S; Duong Tran, T; Hahn, O; Kindler, S; Metelmann, H-R; von Woedtke, T; Masur, K

    2016-03-01

    Over the past few decades, new cold plasma sources have been developed that have the great advantage of operating at atmospheric pressure and at temperatures tolerable by biological material. New applications for these have emerged, especially in the field of dermatology. Recently it was demonstrated that cold atmospheric-pressure plasma positively influences healing of chronic wounds. The potential of cold plasma lies in its capacity to reduce bacterial load in the wound while at the same time stimulating skin cells and therefore promoting wound closure. In recent years, there have been great advances in the understanding of the molecular mechanisms triggered by cold plasma involving signalling pathways and gene regulation in cell culture. To investigate cold plasma-induced effects in ex vivo treated human skin biopsies. Human skin tissue was exposed to cold plasma for different lengths of time, and analysed by immunofluorescence with respect to DNA damage, apoptosis, proliferation and differentiation markers. After cold plasma treatment, the epidermal integrity and keratin expression pattern remained unchanged. As expected, the results revealed an increase in apoptotic cells after 3 and 5 min of treatment. Strikingly, an induction of proliferating basal keratinocytes was detected after cold plasma exposure for 1 and 3 min. As these are the cells that regenerate the epidermis, this could indeed be beneficial for wound closure. We investigated the effect of cold plasma on human skin by detecting molecules for growth and apoptosis, and found that both processes are dependent on treatment time. Therefore, this approach offers promising results for further applications of cold plasma in clinical dermatology. © 2015 British Association of Dermatologists.

  13. Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

    Directory of Open Access Journals (Sweden)

    Noelia Álvarez-Gutiérrez

    2016-03-01

    Full Text Available The challenge of developing effective separation and purification technologies that leave much smaller energy footprints is greater for carbon dioxide (CO2 than for other gases. In addition to its involvement in climate change, CO2 is present as an impurity in biogas and bio-hydrogen (biological production by dark fermentation, in post-combustion processes (flue gas, CO2-N2 and many other gas streams. Selected phenol-formaldehyde resin-based activated carbons prepared in our laboratory have been evaluated under static conditions (adsorption isotherms as potential adsorbents for CO2 separation at sub-atmospheric pressures, i.e., in post-combustion processes or from biogas and bio-hydrogen streams. CO2, H2, N2, and CH4 adsorption isotherms at 25 °C and up to 100 kPa were obtained using a volumetric equipment and were correlated by applying the Sips model. Adsorption equilibrium was then predicted for multicomponent gas mixtures by extending the multicomponent Sips model and the Ideal Adsorbed Solution Theory (IAST in conjunction with the Sips model. The CO2 uptakes of the resin-derived carbons from CO2-CH4, CO2-H2, and CO2-N2 at atmospheric pressure were greater than those of the reference commercial carbon (Calgon BPL. The performance of the resin-derived carbons in terms of equilibrium of adsorption seems therefore relevant to CO2 separation in post-combustion (flue gas, CO2-N2 and in hydrogen fermentation (CO2-H2, CO2-CH4.

  14. Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization.

    Science.gov (United States)

    Vaikkinen, Anu; Haapala, Markus; Kersten, Hendrik; Benter, Thorsten; Kostiainen, Risto; Kauppila, Tiina J

    2012-02-07

    A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (μAPPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different μAPPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in μAPPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production. © 2012 American Chemical Society

  15. Experimental investigation of photoresist etching by kHz AC atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijun, E-mail: lijunwang@mail.xjtu.edu.cn; Zheng, Yashuang; Wu, Chen; Jia, Shenli

    2016-11-01

    Graphical abstract: Pin-ring electrode, double-ring electrode and multi-electrode kHz AC atmospheric pressure plasma jet were used to etch PR on Si wafer, and a corresponding parametric study was carefully investigated. Display Omitted - Highlights: • The surface roughness increases dramatically after APPJ treatment. • The etch rate of the pin-ring electrode APPJ is the highest than that of the multi-electrode APPJ and the double-ring electrode APPJ. • Ar APPJ has a much higher etch rate and more irregular etch trace than He APPJ. • The effective etching initially increases and then decreases with the increment of plasma jet outlet to PR surface distance. - Abstract: In this study, the mechanism of the photoresist (PR) etching by means of a kHz AC atmospheric pressure plasma jet (APPJ) is investigated. The scanning electron (SEM) and the polarizing microscope are used to perform the surface analysis, and the mechanical profilometry is applied to diagnose the etch rate. The results show that granulated structure with numerous microparticles appears at the substrate surface after APPJ treatment, and the etch rate in the etch center is the fastest and gradually slows down to the edge of etch region. In addition, the pin-ring electrode APPJ has the highest etch rate at but easy to damage the Si wafer, the double-ring APPJ is the most stable but requires long time to achieve the ideal etch result, and the etch rate and the etch result of the multi-electrode APPJ fall in between. Ar APPJ had much higher PR etch rate and more irregular etch trace than He APPJ. It is speculated that Ar APPJ is more energetic and effective in transferring reactive species to the PR surface. It is also observed that the effective etch area initially increases and then decreases as plasma jet outlet to the PR surface distance increases.

  16. Eradication of Pseudomonas aeruginosa biofilms by atmospheric pressure non-thermal plasma.

    Directory of Open Access Journals (Sweden)

    Mahmoud Y Alkawareek

    Full Text Available Bacteria exist, in most environments, as complex, organised communities of sessile cells embedded within a matrix of self-produced, hydrated extracellular polymeric substances known as biofilms. Bacterial biofilms represent a ubiquitous and predominant cause of both chronic infections and infections associated with the use of indwelling medical devices such as catheters and prostheses. Such infections typically exhibit significantly enhanced tolerance to antimicrobial, biocidal and immunological challenge. This renders them difficult, sometimes impossible, to treat using conventional chemotherapeutic agents. Effective alternative approaches for prevention and eradication of biofilm associated chronic and device-associated infections are therefore urgently required. Atmospheric pressure non-thermal plasmas are gaining increasing attention as a potential approach for the eradication and control of bacterial infection and contamination. To date, however, the majority of studies have been conducted with reference to planktonic bacteria and rather less attention has been directed towards bacteria in the biofilm mode of growth. In this study, the activity of a kilohertz-driven atmospheric pressure non-thermal plasma jet, operated in a helium oxygen mixture, against Pseudomonas aeruginosa in vitro biofilms was evaluated. Pseudomonas aeruginosa biofilms exhibit marked susceptibility to exposure of the plasma jet effluent, following even relatively short (≈ 10's s exposure times. Manipulation of plasma operating conditions, for example, plasma operating frequency, had a significant effect on the bacterial inactivation rate. Survival curves exhibit a rapid decline in the number of surviving cells in the first 60 seconds followed by slower rate of cell number reduction. Excellent anti-biofilm activity of the plasma jet was also demonstrated by both confocal scanning laser microscopy and metabolism of the tetrazolium salt, XTT, a measure of bactericidal

  17. Degradation of the Neonicotinoid Pesticides in the Atmospheric Pressure Ionization Source

    Science.gov (United States)

    Chai, Yunfeng; Chen, Hongping; Liu, Xin; Lu, Chengyin

    2017-12-01

    During the analysis of neonicotinoid pesticide standards (thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid) by mass spectrometry, the degradation of these pesticides (M-C=N-R is degraded into M-C=O, M is the skeleton moiety, and R is NO2 or CN) was observed in the atmospheric pressure ionization interfaces (ESI and APCI). In APCI, the degradation of all the five neonicotinoid pesticides studied took place, and the primary mechanism was in-source ion/molecule reaction, in which a molecule of water (confirmed by use of H2 18O) attacked the carbon of the imine group accompanying with loss of NH2R (R=NO2, CN). For the nitroguanidine neonicotinoid pesticides (R=NO2, including thiamethoxam, clothianidin, and imidacloprid), higher auxiliary gas heater temperature also contributed to their degradation in APCI due to in-source pyrolysis. The degradation of the five neonicotinoid pesticides studied in ESI was not significant. In ESI, only the nitroguanidine neonicotinoid pesticides could generate the degradation products through in-source fragmentation mechanism. The degradation of cyanoamidine neonicotinoid pesticides (R=CN, including acetamiprid and thiacloprid) in ESI was not observed. The degradation of neonicotinoid pesticides in the ion source of mass spectrometer renders some adverse consequences, such as difficulty interpreting the full-scan mass spectrum, reducing the sensitivity and accuracy of quantitative analysis, and misleading whether these pesticides have degraded in the real samples. Therefore, a clear understanding of these unusual degradation reactions should facilitate the analysis of neonicotinoid pesticides by atmospheric pressure ionization mass spectrometry. [Figure not available: see fulltext.

  18. DNA damage in oral cancer and normal cells induced by nitrogen atmospheric pressure plasma jets

    Science.gov (United States)

    Han, Xu; Kapaldo, James; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

    2015-09-01

    Nitrogen atmospheric pressure plasma jets (APPJs) have been shown to effectively induce DNA double strand breaks in SCC25 oral cancer cells. The APPJ source constructed in our laboratory operates based on dielectric barrier discharge. It consists of two copper electrodes alternatively wrapping around a fused silica tube with nitrogen as a feed gas. It is generally more challenging to ignite plasma in N2 atmosphere than in noble gases. However, N2 provides additional advantages such as lower costs compared to noble gases, thus this design can be beneficial for the future long-term clinical use. To compare the effects of plasma on cancer cells (SCC25) and normal cells (OKF), the cells from both types were treated at the same experimental condition for various treatment times. The effective area with different damage levels after the treatment was visualized as 3D maps. The delayed damage effects were also explored by varying the incubation times after the treatment. All of these studies are critical for a better understanding of the damage responses of cellular systems exposed to the plasma radiation, thus are useful for the development of the advanced plasma cancer therapy. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through Grant No. DE-FC02-04ER15533.

  19. Experimental Research on Water Boiling Heat Transfer on Horizontal Copper Rod Surface at Sub-Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Li-Hua Yu

    2015-09-01

    Full Text Available In recent years, water (R718 as a kind of natural refrigerant—which is environmentally-friendly, safe and cheap—has been reconsidered by scholars. The systems of using water as the refrigerant, such as water vapor compression refrigeration and heat pump systems run at sub-atmospheric pressure. So, the research on water boiling heat transfer at sub-atmospheric pressure has been an important issue. There are many research papers on the evaporation of water, but there is a lack of data on the characteristics at sub-atmospheric pressures, especially lower than 3 kPa (the saturation temperature is 24 °C. In this paper, the experimental research on water boiling heat transfer on a horizontal copper rod surface at 1.8–3.3 kPa is presented. Regression equations of the boiling heat transfer coefficient are obtained based on the experimental data, which are convenient for practical application.

  20. Mechanisms behind surface modification of polypropylene film using an atmospheric-pressure plasma jet

    Science.gov (United States)

    Shaw, David; West, Andrew; Bredin, Jerome; Wagenaars, Erik

    2016-12-01

    Plasma treatments are common for increasing the surface energy of plastics, such as polypropylene (PP), to create improved adhesive properties. Despite the significant differences in plasma sources and plasma properties used, similar effects on the plastic film can be achieved, suggesting a common dominant plasma constituent and underpinning mechanism. However, many details of this process are still unknown. Here we present a study into the mechanisms underpinning surface energy increase of PP using atmospheric-pressure plasmas. For this we use the effluent of an atmospheric-pressure plasma jet (APPJ) since, unlike most plasma sources used for these treatments, there is no direct contact between the plasma and the PP surface; the APPJ provides a neutral, radical-rich environment without charged particles and electric fields impinging on the PP surface. The APPJ is a RF-driven plasma operating in helium gas with small admixtures of O2 (0-1%), where the effluent propagates through open air towards the PP surface. Despite the lack of charged particles and electric fields on the PP surface, measurements of contact angle show a decrease from 93.9° to 70.1° in 1.4 s and to 35° in 120 s, corresponding to a rapid increase in surface energy from 36.4 mN m-1 to 66.5 mN m-1 in the short time of 1.4 s. These treatment effects are very similar to what is found in other devices, highlighting the importance of neutral radicals produced by the plasma. Furthermore, we find an optimum percentage of oxygen of 0.5% within the helium input gas, and a decrease of the treatment effect with distance between the APPJ and the PP surface. These observed effects are linked to two-photon absorption laser-induced fluorescence spectroscopy (TALIF) measurements of atomic oxygen density within the APPJ effluent which show similar trends, implying the importance of this radical in the surface treatment of PP. Analysis of the surface reveals a two stage mechanism for the production of polar

  1. Correlation of phase resolved current, emission and surface charge measurements in an atmospheric pressure helium jet

    Science.gov (United States)

    Gerling, Torsten; Wild, Robert; Vasile Nastuta, Andrei; Wilke, Christian; Weltmann, Klaus-Dieter; Stollenwerk, Lars

    2015-07-01

    The interaction of an atmospheric pressure plasma jet with two different surfaces (conducting and dielectric) is investigated using a setup with two ring electrodes around a dielectric capillary. For diagnostics, phase resolved ICCD-imaging, current measurements and surface charge measurements are applied. The results show the correlation of plasma dynamics with the deposition of surface charge and electrical current signals. Further, the influence of the distance between surface and jet capillary on the surface charge distribution is presented. A complex discharge dynamic is found with a dielectric barrier discharge between the ring electrodes and back-and-forth bullet propagation outside the capillary. A conducting channel connecting the jet nozzle and the surface is found. This correlates well with the observed charge exchange on the surface. The number of formed channels and the average deposited charge density on the surface is found to be strongly sensitive to the jet distance from the surface. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  2. Analysis of nitrogen-based explosives with desorption atmospheric pressure photoionization mass spectrometry.

    Science.gov (United States)

    Kauppila, T J; Flink, A; Pukkila, J; Ketola, R A

    2016-02-28

    Fast methods that allow the in situ analysis of explosives from a variety of surfaces are needed in crime scene investigations and home-land security. Here, the feasibility of the ambient mass spectrometry technique desorption atmospheric pressure photoionization (DAPPI) in the analysis of the most common nitrogen-based explosives is studied. DAPPI and desorption electrospray ionization (DESI) were compared in the direct analysis of trinitrotoluene (TNT), trinitrophenol (picric acid), octogen (HMX), cyclonite (RDX), pentaerythritol tetranitrate (PETN), and nitroglycerin (NG). The effect of different additives in DAPPI dopant and in DESI spray solvent on the ionization efficiency was tested, as well as the suitability of DAPPI to detect explosives from a variety of surfaces. The analytes showed ions only in negative ion mode. With negative DAPPI, TNT and picric acid formed deprotonated molecules with all dopant systems, while RDX, HMX, PETN and NG were ionized by adduct formation. The formation of adducts was enhanced by addition of chloroform, formic acid, acetic acid or nitric acid to the DAPPI dopant. DAPPI was more sensitive than DESI for TNT, while DESI was more sensitive for HMX and picric acid. DAPPI could become an important method for the direct analysis of nitroaromatics from a variety of surfaces. For compounds that are thermally labile, or that have very low vapor pressure, however, DESI is better suited. Copyright © 2016 John Wiley & Sons, Ltd.

  3. Production of TEMPO by O atoms in atmospheric pressure non-thermal plasma–liquid interactions

    Science.gov (United States)

    Elg, Daniel T.; Yang, I.-Wei; Graves, David B.

    2017-11-01

    Non-thermal atmospheric pressure plasmas enable plasma treatment of surfaces without requiring a low-pressure environment. These plasmas are currently of interest for, among other things, their biomedical applications, many of which are enabled by production of reactive oxygen and nitrogen species (RONS). Plasma–liquid interactions are especially important due to the high amounts of water in biological materials. However, the chemistries of these plasmas are very complex and are not well-understood. One method to quantify plasma–liquid interactions is to dissolve a reactant into the liquid which, when exposed to plasma-created RONS, forms a measurable product. In particular, the oxidation of the spin trap TEMP to TEMPO has been used to track trends in reactive oxygen species. However, the effect of individual species on TEMP has not previously been determined. This paper differentiates the oxidation of TEMP due to various oxygen species produced by a He plasma jet operating in a controllable environment. Oxidation of TEMP is mainly to O atoms, with small or negligible contributions from other species. Thus, the TEMPO yield will also be used to illuminate trends in O atom production.

  4. Improved Correction of Atmospheric Pressure Data Obtained by Smartphones through Machine Learning

    Directory of Open Access Journals (Sweden)

    Yong-Hyuk Kim

    2016-01-01

    Full Text Available A correction method using machine learning aims to improve the conventional linear regression (LR based method for correction of atmospheric pressure data obtained by smartphones. The method proposed in this study conducts clustering and regression analysis with time domain classification. Data obtained in Gyeonggi-do, one of the most populous provinces in South Korea surrounding Seoul with the size of 10,000 km2, from July 2014 through December 2014, using smartphones were classified with respect to time of day (daytime or nighttime as well as day of the week (weekday or weekend and the user’s mobility, prior to the expectation-maximization (EM clustering. Subsequently, the results were analyzed for comparison by applying machine learning methods such as multilayer perceptron (MLP and support vector regression (SVR. The results showed a mean absolute error (MAE 26% lower on average when regression analysis was performed through EM clustering compared to that obtained without EM clustering. For machine learning methods, the MAE for SVR was around 31% lower for LR and about 19% lower for MLP. It is concluded that pressure data from smartphones are as good as the ones from national automatic weather station (AWS network.

  5. Influence of the coupling between an atmospheric pressure ion mobility spectrometer and the low pressure ion inlet of a mass spectrometer on the mobility measurement

    Directory of Open Access Journals (Sweden)

    Gunzer Frank

    2016-01-01

    Full Text Available Ion mobility spectrometers (IMS are versatile gas analyzers. Due to their small size and robustness, combined with a very high sensitivity, they are often used in gas sensing applications such as environmental monitoring. In order to improve the selectivity, they are typically combined with a mass spectrometer (MS. Since IMS works at atmospheric pressure, and MS works at vacuum, a special interface reducing the pressure over normally two stages has to be used. In this paper the influence of this coupling of different pressure areas on the IMS signal will be analyzed with help of finite elements method simulations.

  6. Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds.

    Science.gov (United States)

    Shao, Pei-Lin; Liao, Jiunn-Der; Wong, Tak-Wah; Wang, Yi-Cheng; Leu, Steve; Yip, Hon-Kan

    2016-01-01

    Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT), and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3) and laminin in the wound area were assessed using histological and immunohistochemistry (IHC) analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically.

  7. Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds.

    Directory of Open Access Journals (Sweden)

    Pei-Lin Shao

    Full Text Available Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT, and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3 and laminin in the wound area were assessed using histological and immunohistochemistry (IHC analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically.

  8. Carbon dioxide, temperature, salinity, and atmospheric pressure from surface underway survey in the North Pacific from January 1998 to January 2004 (NODC Accession 0045502)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea surface pCO2, sea surface temperature, sea surface salinity, and atmospheric pressure measurements collected in the North Pacific as part of the NOAA Office of...

  9. Experiment plan for characterization of the properties of molten rock at atmospheric and elevated pressures: Magma Energy Research Project

    Energy Technology Data Exchange (ETDEWEB)

    Modreski, P.J.

    1979-02-01

    Knowledge of the properties of molten rock (magma) is of importance to the Magma Energy Research Project of Sandia Laboratories. Facilities have been set up at Sandia to study the physical properties, chemistry, and corrosive nature of magma to 1600/sup 0/C and from atmospheric pressure to 4 kbar (400 MPa). Experiments at atmospheric pressure are being done in the presence of multicomponent gas mixtures to control the chemical activities of oxygen and sulfur. The high-pressure apparatus includes cold-seal small-volume pressure vessels (to 1100/sup 0/C and 1 kbar) and a large (750 cm/sup 3/ sample volume), internally heated pressure vessel (to 1600/sup 0/C and 4 kbar). The large vessel contains a number of penetrations for electrical leads and pressure lines, and is linked to a computer for data acquisition and control of experiments. Water and other dissolved volatiles (CO/sub 2/, CO, SO/sub 2/, S/sub 2/, H/sub 2/S, HCl, HF) have significant effects on all the properties of magma, and these effects will be studied in the high-pressure apparatus. Phase equilibria, viscosity, electrical conductivity, and materials compatibility will be the first properties to be examined under pressure. This report includes a review of the nature and chemical basis for the effects of dissolved volatiles on these properties of magma. 70 references, 10 figures.

  10. Novel diagnostics for direct measurements of radical densities in atmospheric pressure plasma jets

    Science.gov (United States)

    Wagenaars, Erik

    2017-10-01

    Atmospheric-pressure plasma jets (APPJs) are widely studied for potential applications in industry and healthcare, e.g. surface modification of plastics, plasma medicine and photoresist removal. These plasmas can operate in open air, remain at room temperature and still have a non-equilibrium chemistry. Even though the exact mechanisms through which APPJs affect target surfaces remain largely unknown, it is clear that reactive species play a pivotal role in the success of APPJs. Therefore, reactive species diagnostics of APPJs play an important role in further developing our understanding of the plasma chemistry and will enable increases in treatment efficacy. Two-photon Absorption Laser Induced Fluorescence (TALIF) is a well-known technique for the measurement of absolute densities of atomic radicals such as O, N and H. Unfortunately, application of this technique on APPJs that are operating under realistic conditions for applications, i.e. in open air and with complex admixtures, is not straightforward. The highly collisional environment of APPJs means that collisional quenching of the laser-excited state becomes significant and needs to be taken into account. For well-controlled atmospheres and simple admixtures the effect can be estimated using quenching coefficients, however under realistic operating conditions the identity and density of the quenching partners is unknown due to the complexity of the plasma chemistry. I will present a picosecond TALIF diagnostic which uses a sub-nanosecond laser and iCCD camera that allows the measurement of the quenching-affected fluorescence decay rate directly, enabling absolute measurements of O and N density maps in the open-air effluent of an APPJ. The author acknowledges his collaborators at UoY, A. West, J. Bredin, S. Schroeter, K. Niemi, T. Gans, J. Dedrick and D. O'Connell and support from the UK EPSRC (EP/K018388/1 & EP/H003797/1).

  11. Physiological responses to low atmospheric pressure stunning and the implications for welfare.

    Science.gov (United States)

    McKeegan, D E F; Sandercock, D A; Gerritzen, M A

    2013-04-01

    In low atmospheric pressure stunning (LAPS), poultry are rendered unconscious before slaughter by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia. The effects of LAPS are not instantaneous, so there are legitimate welfare concerns around the experience of birds before loss of consciousness. Using self-contained telemetry logging units, high-quality continuous electroencephalogram (EEG) and electrocardiogram (EKG) recordings were obtained from 28 broiler chickens during exposure to LAPS in a commercial poultry processing plant. Application of LAPS was associated with changes in the EEG pattern in the form of increases in total power, decreases in mean frequency, and in particular, increases in slow-wave (delta) activity, indicating a gradual loss of consciousness. Increased delta wave activity was seen within 10 s of LAPS onset and consistently thereafter, peaking at 30 s into LAPS at which point the EEG signal shared characteristics with that of birds in a surgical plane of anesthesia. During LAPS, heart rate consistently decreased, with more pronounced bradycardia and arrhythmia observed after 30 s. No heart rate increases were observed in the period when the birds were potentially conscious. After an initial quiescent period, brief body movements (presumed to be ataxia/loss of posture) were seen on average at 39 s into the LAPS process. Later (after 120 s on average), artifacts related to clonic (wing flapping) and tonic (muscle spasms) convulsions were observed in the EKG recordings. Based on EEG analysis and body movement responses, a conservative estimate of time to loss of consciousness is approximately 40 s. The lack of behavioral responses indicating aversion or escape and absence of heart rate elevation in the conscious period strongly suggest that birds do not find LAPS induction distressing. Collectively, the results suggest that LAPS is a humane approach that has the potential to improve the welfare of poultry at

  12. Development and Characterization of a Hybrid Atmospheric Pressure Plasma Electrospinning System for Nanofiber Enhancement

    Science.gov (United States)

    Nowak, Joshua Michael

    A hybrid atmospheric pressure-electrospinning plasma system was developed to be used for the production of nanofibers and enhance their performance for various applications. Electrospun nanofibers are excellent candidates for protective clothing in the field of chemical and biological warfare defense; however, nanofibers are structurally weak and easily abrade and tear. They can be strengthened through the support of a substrate fabric, but they do not adhere well to substrates. Through the use of the developed hybrid system with either pure He or He/O2 (99/1) feed gas, adherence to the substrate along with abrasion and flex resistance were improved. The plasma source was diagnosed electrically, thermally, and optically. An equivalent circuit model was developed for non-thermal, highly collisional plasmas that can solve for average electron temperature and electron number density. The obtained temperatures (~ 3eV) correlate very well with the results of a neutral Bremsstrahlung continuum matching technique that was also employed. Using the temperatures and number densities obtained from the circuit model and the optical spectroscopy, a global chemical kinetics code was written in order to solve for radical and ion concentrations. This code shows that there are significant concentrations of oxygen radicals present. The XPS analysis confirmed that there was an increase of surface oxygen from 11.1% up to 16.6% for the He/O2 plasma and that the C-O bonding, which was not present in the control samples, has increased to 45.4%. The adhesive strength to the substrate has a significant increase of 81% for helium plasma and 144% for He/O2 plasma; however, these values remain below the desired values for protective clothing applications. The hybrid system displayed the ability to oxygenate nanofibers as they are being electrospun and shows the feasibility of making other surface modifications. The developed circuit model and chemical kinetics code both show promise as tools

  13. Characterizations of atmospheric pressure low temperature plasma jets and their applications

    Science.gov (United States)

    Karakas, Erdinc

    2011-12-01

    Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio

  14. Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L.; Mancinelli, B. R. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina) and Instituto de Fisica del Plasma (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas y Naturales UBA Ciudad Universitaria Pab. I, (1428) Buenos Aires (Argentina)

    2012-09-15

    Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.

  15. Thin-layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemica lionization

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikova, Olga S [ORNL; Van Berkel, Gary J [ORNL

    2010-01-01

    An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high-performance thin-layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read-out resolution, detection limits, and surface type are discussed.

  16. Accurate quantitation of pentaerythritol tetranitrate and its degradation products using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

    NARCIS (Netherlands)

    Brust, H.; Asten, A. van; Koeberg, M.; Dalmolen, J.; Heijden, A.E.D.M. van der; Schoenmakers, P.

    2014-01-01

    After an explosion of pentaerythritol tetranitrate (PETN), its degradation products pentaerythritol trinitrate (PETriN), dinitrate (PEDiN) and mononitrate (PEMN) were detected using liquid chromatography-atmospheric-pressure chemical-ionization-mass spectrometry (LC-APCI-MS). Discrimination between

  17. Anisole, a new dopant for atmospheric pressure photoionization mass spectrometry of low proton affinity, low ionization energy compounds

    NARCIS (Netherlands)

    Kauppila, TJ; Kostiainen, R; Bruins, AP

    2004-01-01

    Atmospheric pressure photoionization (APPI) is a novel method of ionization in liquid chromatography/mass spectrometry (LC/MS). It was originally developed in order to broaden the range of LC/MS ionizable compounds towards less polar compounds that cannot be analyzed by electrospray (ESI) and

  18. Cold atmospheric pressure plasma treatment of ready-to-eat meat: Inactivation of Listeria innocua and changes in product quality

    DEFF Research Database (Denmark)

    Rød, Sara Katrine; Hansen, Flemming; Leipold, Frank

    2012-01-01

    The application of cold atmospheric pressure plasma for decontamination of a sliced ready-to-eat (RTE) meat product (bresaola) inoculated with Listeria innocua was investigated. Inoculated samples were treated at 15.5, 31, and 62 W for 2–60 s inside sealed linear-low-density-polyethylene bags...

  19. Diode laser absorption measurement and analysis of HCN in atmospheric-pressure, fuel-rich premixed methane/air flames

    NARCIS (Netherlands)

    Gersen, Sander; Mokhov, A. V.; Levinsky, H. B.

    2008-01-01

    Measurements of HCN in flat, fuel-rich premixed methane/air flames at atmospheric pressure are reported. Quartz-microprobe sampling followed by wavelength modulation absorption spectroscopy with second harmonic detection was used to obtain an overall measurement uncertainty of better than 20% for

  20. Gene Transfection Method Using Atmospheric Pressure Dielectric-Barrier Discharge Plasmas

    Science.gov (United States)

    Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

    2013-09-01

    Gene transfection which is the process of deliberately introducing nucleic acids into cells is expected to play an important role in medical treatment because the process is necessary for gene therapy and creation of induced pluripotent stem (iPS) cells. However, the conventional transfection methods have some problems, so we focus attention on promising transfection methods by atmospheric pressure dielectric-barrier discharge (AP-DBD) plasmas. AP-DBD He plasmas are irradiated to the living cell covered with genes. Preliminarily, we use fluorescent dye YOYO-1 instead of the genes and use LIVE/DEAD Stain for cell viability test, and we analyze the transfection efficiency and cell viability under the various conditions. It is clarified that the transfection efficiency is strongly dependence on the plasma irradiation time and cell viability rates is high rates (>90%) regardless of long plasma irradiation time. These results suggest that ROS (Reactive Oxygen Species) and electric field generated by the plasma affect the gene transfection. In addition to this (the plasma irradiation time) dependency, we now investigate the effect of the plasma irradiation under the various conditions.

  1. Spatially-Selective Membrane Permeabilization Induced by Cell-Solution Electrode Atmospheric Pressure Plasma Irradiation

    Science.gov (United States)

    Sasaki, Shota; Hokari, Yutaro; Kanzaki, Makoto; Kaneko, Toshiro

    2015-09-01

    Gene transfection, which is the process of deliberately introducing nucleic acids into cells, is expected to play an important role in medical treatment because the process is necessary for gene therapy and creation of induced pluripotent stem (iPS) cells. However, the conventional transfection methods have some problems, so we focus attention on promising transfection methods by atmospheric pressure plasma (APP). We have previously reported that the cell membrane permeability, which is closely related with gene transfection, is improved using a cell-solution electrode for generating He-APP. He-APP is irradiated to the solution containing the adherent cells and delivery materials such as fluorescent dyes (YOYO-1) and plasmid DNA (GFP). In case of YOYO-1 delivery, more than 80% of cells can be transferred only in the plasma-irradiated area and the spatially-selective membrane permeabilization is realized by the plasma irradiation. In addition, it is confirmed that plasmid DNA is transfected and the GFP genes are expressed using same APP irradiation system with no obvious cellular damage.

  2. Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jia Caixia [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education) and Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Chen Ping, E-mail: chenping_898@126.com [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education) and Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China) and Liaoning Key Laboratory of Advanced Polymer Matrix Composites Manufacturing Technology, Shenyang Aerospace University, Shenyang 110034 (China); Liu Wei [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education) and Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Dalian University of Education, Dalian 116021 (China); Li Bin; Wang Qian [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education) and Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2011-02-15

    Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm{sup 3} plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, C=O and O=C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

  3. Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

    Science.gov (United States)

    Jia, Caixia; Chen, Ping; Liu, Wei; Li, Bin; Wang, Qian

    2011-02-01

    Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm3 plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, Cdbnd O and Odbnd C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

  4. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2018-03-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  5. Effect of external electric and magnetic field on propagation of atmospheric pressure plasma jet

    Science.gov (United States)

    Zhu, Ping; Meng, Zhaozhong; Hu, Haixin; Ouyang, Jiting

    2017-10-01

    The behaviors of atmospheric pressure plasma jet produced by a coplanar dielectric barrier discharge (CDBD) in helium in external electrostatic and magnetic field are investigated experimentally. Time-resolved ICCD images of jet in electric field, magnetic field, and floating metal ring are recorded, respectively. The results show that the jet dynamics is affected significantly by a metal ring, an electric, and/or a magnetic field. In a transverse electric field, the jet shows behavior of deflection, broadening, and shortening according to the structure of electric field. In a transverse magnetic field, the jet deflects to up or down depending on the magnetic direction. The jet can be slowed down or obstructed by a floating metal ring on the jet path, but will still pass through the tube at higher applied voltages of DBD, without significant change in jet length or shape out of the tube compared with that without metal ring. A positive DC voltage on the metal ring helps to improve the jet length, but a negative voltage will reduce the length or completely stop the jet. The electric field to sustain the jet in helium is estimated to be about 24 ± 15 kV/cm from this experiment.

  6. Laser Microdissection and Atmospheric Pressure Chemical Ionization Mass Spectrometry Coupled for Multimodal Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

    2013-01-01

    This paper describes the coupling of ambient laser ablation surface sampling, accomplished using a laser capture microdissection system, with atmospheric pressure chemical ionization mass spectrometry for high spatial resolution multimodal imaging. A commercial laser capture microdissection system was placed in close proximity to a modified ion source of a mass spectrometer designed to allow for sampling of laser ablated material via a transfer tube directly into the ionization region. Rhodamine 6G dye of red sharpie ink in a laser etched pattern as well as cholesterol and phosphatidylcholine in a cerebellum mouse brain thin tissue section were identified and imaged from full scan mass spectra. A minimal spot diameter of 8 m was achieved using the 10X microscope cutting objective with a lateral oversampling pixel resolution of about 3.7 m. Distinguishing between features approximately 13 m apart in a cerebellum mouse brain thin tissue section was demonstrated in a multimodal fashion including co-registered optical and mass spectral chemical images.

  7. An experimental study of atmospheric pressure dielectric barrier discharge (DBD) in argon

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, D. P. [Department of Natural Sciences, School of Science, Kathmandu University, Dhulikhel (Nepal); Tyata, R. B. [Department of Natural Sciences, School of Science, Kathmandu University, Dhulikhel, Nepal and Department of Electrical, Khwopa College of Engineering, Libali-2, Bhaktapur (Nepal); Shrestha, R. [Department of Natural Sciences, School of Science, Kathmandu University, Dhulikhel, Nepal and Department of Physics, Basu College, Kalighat, Byasi, Bhaktapur (Nepal); Wong, C. S. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-03-05

    In this paper, experimental results on atmospheric pressure argon dielectric barrier discharge (DBD) have been presented. The discharge was generated using a high voltage (0 to 20 kV) power supply operating at frequency of 10 to 30 kHz and was studied by means of electrical and optical measurements. A homogeneous and steady discharge was observed between the electrodes with gap spacing from 1 mm to 3 mm and with a dielectric barrier of thickness 1.5 mm while argon gas is fed at a controlled flow rate of 2liter per min. The electron temperature (T{sub e}) and electron density (n{sub e}) of the plasma have been determined by means of optical emission spectroscopy. Our results show that the electron density is of the order of 10{sup 16} cm{sup −3} while the electron temperature is estimated to be ∼ 1 eV. The homogeneity and non-thermal nature of the discharge were utilized in the investigation of the change in wettabilty of a polymer sample subjected to the treatment by the discharge. Contact angle analysis showed that the discharge was effective in improving the wettability of low density Polyethylene (LDPE) polymer sample after the treatment.

  8. Improvement of wettability and absorbancy of textile using atmospheric pressure dielectric barrier discharge

    Science.gov (United States)

    Ghimire, Bhagirath; Subedi, Deepak Prasad; Khanal, Raju

    2017-08-01

    In this study, cotton textile samples, commonly used in making quilt covers were subjected to atmospheric pressure dielectric barrier discharge treatment to study their surface wettability and absorbancy. Samples were treated in the discharge using a rotatory mechanism and the effects of plasma treatment were examined by contact angle measurement and weight measurement. Air plasma treatment was successful in incorporating hydrophilic functional groups on the textile surface due to which wettability as well as absorbancy immediately after the treatment were highly improved. Effects of plasma treatment started to appear only after 20 cycles (9 mins) and got saturated after 24 cycles (10.8 mins) of treatment. The contact angle reduced from 137 ° (untreated sample) to a value less than 30 ° while absorbancy increased by more than two times as compared to untreated sample. Also, the aging behavior of the plasma treated samples were studied for about a week after plasma treatment. It was observed that the induced oxygen containing groups re-oriented into the bulk of the material during their storage in the environment due to which initial properties of the samples recovered gradually. Our results indicate that low temperature plasma can be successfully applied to modify the properties of textiles and textile industries could utilize this by standardization.

  9. A tomographic visualization of electric discharge sound fields in atmospheric pressure plasma using laser diffraction

    Science.gov (United States)

    Nakamiya, Toshiyuki; Mitsugi, Fumiaki; Iwasaki, Yoichiro; Ikegami, Tomoaki; Tsuda, Ryoichi; Sonoda, Yoshito; Danuta Stryczewska, Henryka

    2013-02-01

    The phase modulation of transparent gas can be detected using Fraunhofer diffraction technique, which we call optical wave microphone (OWM). The OWM is suitable for the detection of sonic wave from audible sound to ultrasonic wave. Because this technique has no influence on sound field or electric field during the measurement, we have applied it to the sound detection for the electric discharges. There is almost no research paper that uses the discharge sound to examine the electrical discharge phenomenon. Two-dimensional visualization of the sound field using the OWM is also possible when the computerized tomography (CT) is combined. In this work, coplanar dielectric barrier discharge sin different gases of Ar, N2, He were characterized via the OWM as well as applied voltage and discharge current. This is the first report to investigate the influence of the type of the atmospheric gas on the two-dimensional sound field distribution for the coplanar dielectric barrier discharge using the OWM with CT. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  10. Ionization Capabilities of Hydronium Ions and High Electric Fields Produced by Atmospheric Pressure Corona Discharge.

    Science.gov (United States)

    Sato, Natsuhiko; Sekimoto, Kanako; Takayama, Mitsuo

    2016-01-01

    Atmospheric pressure corona discharge (APCD) was applied to the ionization of volatile organic compounds. The mass spectra of analytes having aromatic, phenolic, anilinic, basic and aliphatic in nature were obtained by using vapor supply and liquid smear supply methods. The vapor supply method mainly gave protonated analytes [A+H]+ caused by proton transfer from hydronium ion H3O+, except for benzene, toluene and n-hexane that have lower proton affinity. The use of the liquid smear supply method resulted in the formation of molecular ion A·+ and/or dehydride analyte [A-H]+, according to the nature of analytes used. The formation of A·+ without fragment ions could be explained by the electron tunneling via high electric fields 108 V/m at the tip of the corona needle. The dehydride analytes [A-H]+ observed in the mass spectra of n-hexane, di- and tributylamines may be explained by the hydride abstraction from the alkyl chains by the hydronium ion. The hydronium ion can play the two-roles for analytes, i.e., the proton donor to form [A+H]+ and the hydride acceptor to form [A-H]+.

  11. Inactivation of virus in solution by cold atmospheric pressure plasma: identification of chemical inactivation pathways

    Science.gov (United States)

    Aboubakr, Hamada A.; Gangal, Urvashi; Youssef, Mohammed M.; Goyal, Sagar M.; Bruggeman, Peter J.

    2016-05-01

    Cold atmospheric pressure plasma (CAP) inactivates bacteria and virus through in situ production of reactive oxygen and nitrogen species (RONS). While the bactericidal and virucidal efficiency of plasmas is well established, there is limited knowledge about the chemistry leading to the pathogen inactivation. This article describes a chemical analysis of the CAP reactive chemistry involved in the inactivation of feline calicivirus. We used a remote radio frequency CAP produced in varying gas mixtures leading to different plasma-induced chemistries. A study of the effects of selected scavengers complemented with positive control measurements of relevant RONS reveal two distinctive pathways based on singlet oxygen and peroxynitrous acid. The first mechanism is favored in the presence of oxygen and the second in the presence of air when a significant pH reduction is induced in the solution by the plasma. Additionally, smaller effects of the H2O2, O3 and \\text{NO}2- produced were also found. Identification of singlet oxygen-mediated 2-imidazolone/2-oxo-His (His  +14 Da)—an oxidative modification of His 262 comprising the capsid protein of feline calicivirus links the plasma induced singlet oxygen chemistry to viral inactivation.

  12. The role of VUV radiation in the inactivation of bacteria with an atmospheric pressure plasma jet

    CERN Document Server

    Schneider, Simon; Ellerweg, Dirk; Denis, Benjamin; Narberhaus, Franz; Bandow, Julia E; Benedikt, Jan

    2011-01-01

    A modified version of a micro scale atmospheric pressure plasma jet (\\mu-APPJ) source, so-called X-Jet, is used to study the role of plasma generated VUV photons in the inactivation of E. coli bacteria. The plasma is operated in He gas or a He/O2 mixture and the X-Jet modification of the jet geometry allows effective separation of heavy reactive particles (such as O atoms or ozone molecules) from the plasma-generated photons. The measurements of the evolution of zone of inhibitions formed in monolayers of vegetative E. coli bacteria, of VUV emission intensity and of positive ion spectra show that photochemistry in the gas phase followed by photochemistry products impacting on bacteria can result in bacterial inactivation. Interestingly, this process is more effective than direct inactivation by VUV radiation damage. Mainly protonated water cluster ions are detected by mass spectrometry indicating that water impurity has to be carefully considered. The measurements indicate that the combination of the presence...

  13. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2017-12-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  14. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    Directory of Open Access Journals (Sweden)

    Asma Begum

    2013-06-01

    Full Text Available In this paper He-discharge (plasma jet/bullet in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 1011 cm-3 and it reaches to the maximum of 1012 cm-3.

  15. Evaluation of pathogen inactivation on sliced cheese induced by encapsulated atmospheric pressure dielectric barrier discharge plasma.

    Science.gov (United States)

    Yong, Hae In; Kim, Hyun-Joo; Park, Sanghoo; Alahakoon, Amali U; Kim, Kijung; Choe, Wonho; Jo, Cheorun

    2015-04-01

    Pathogen inactivation induced by atmospheric pressure dielectric barrier discharge (DBD) (250 W, 15 kHz, air discharge) produced in a rectangular plastic container and the effect of post-treatment storage time on inactivation were evaluated using agar plates and cheese slices. When agar plates were treated with plasma, populations of Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes showed 3.57, 6.69, and 6.53 decimal reductions at 60 s, 45 s, and 7 min, respectively. When the pathogens tested were inoculated on cheese slices, 2.67, 3.10, and 1.65 decimal reductions were achieved at the same respective treatment times. The post-treatment storage duration following plasma treatment potently affected further reduction in pathogen populations. Therefore, the newly developed encapsulated DBD-plasma system for use in a container can be applied to improve the safety of sliced cheese, and increasing post-treatment storage time can greatly enhance the system's pathogen-inactivation efficiency. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Destruction of chemical warfare surrogates using a portable atmospheric pressure plasma jet

    Science.gov (United States)

    Škoro, Nikola; Puač, Nevena; Živković, Suzana; Krstić-Milošević, Dijana; Cvelbar, Uroš; Malović, Gordana; Petrović, Zoran Lj.

    2018-01-01

    Today's reality is connected with mitigation of threats from the new chemical and biological warfare agents. A novel investigation of cold plasmas in contact with liquids presented in this paper demonstrated that the chemically reactive environment produced by atmospheric pressure plasma jet (APPJ) is potentially capable of rapid destruction of chemical warfare agents in a broad spectrum. The decontamination of three different chemical warfare agent surrogates dissolved in liquid is investigated by using an easily transportable APPJ. The jet is powered by a kHz signal source connected to a low-voltage DC source and with He as working gas. The detailed investigation of electrical properties is performed for various plasmas at different distances from the sample. The measurements of plasma properties in situ are supported by the optical spectrometry measurements, whereas the high performance liquid chromatography measurements before and after the treatment of aqueous solutions of Malathion, Fenitrothion and Dimethyl Methylphosphonate. These solutions are used to evaluate destruction and its efficiency for specific neural agent simulants. The particular removal rates are found to be from 56% up to 96% during 10 min treatment. The data obtained provide basis to evaluate APPJ's efficiency at different operating conditions. The presented results are promising and could be improved with different operating conditions and optimization of the decontamination process.

  17. Non-thermal atmospheric pressure plasma functionalized dental implant for enhancement of bacterial resistance and osseointegration.

    Science.gov (United States)

    Lee, Jung-Hwan; Jeong, Won-Seok; Seo, Seog-Jin; Kim, Hae-Won; Kim, Kyoung-Nam; Choi, Eun-Ha; Kim, Kwang-Mahn

    2017-03-01

    Even though roughened titanium (Ti) and Ti alloys have been clinically used as dental implant, they encourage bacterial adhesion, leading to failure of the initial stability. Here, the non-thermal atmospheric pressure plasma jet (NTAPPJ) functionalized Ti and Ti alloy were investigated to promote cellular activities but inhibit the initial attachment of the adherent pioneer bacterium, Streptococcus sanguinis, without topographical changes. After the produced radicals from NTAPPJ were characterized, bacterial adhesion to specimens was assessed by PrestoBlue assay and live-dead staining with or without the NTAPPJ functionalizing. After the surface was characterized using optical profilometry, X-ray photoelectron spectroscopy and contact angle analysis, the ions released from the specimens were investigated. In vitro initial cell attachment (4h or 24h) with adhesion images and alkaline phosphatase activity (ALP, 14 days) measurements were performed using rat bone marrow-derived mesenchymal stem cells. The initial bacterial adhesion to the Ti and Ti alloy was significantly inhibited after NTAPPJ functionalizing (pammonia and air, p<0.05). The initial cell adhesion with well-developed vinculin localization and consequent ALP activity at 14days to the NTAPPJ-functionalized specimens were superior to the non-treated specimens. For the promising success of dental implants, NTAPPJ functionalizing is suggested as a novel surface modification technique; this technique can help ensure the success of integration between the dental implants and bone tissues with less concern of inflammation. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Atmospheric pressure plasma deposition of antimicrobial coatings on non-woven textiles

    Science.gov (United States)

    Nikiforov, Anton Yu.; Deng, Xiaolong; Onyshchenko, Iuliia; Vujosevic, Danijela; Vuksanovic, Vineta; Cvelbar, Uros; De Geyter, Nathalie; Morent, Rino; Leys, Christophe

    2016-08-01

    A simple method for preparation of nanoparticle incorporated non-woven fabric with high antibacterial efficiency has been proposed based on atmospheric pressure plasma process. In this work direct current plasma jet stabilized by fast nitrogen flow was used as a plasma deposition source. Three different types of the nanoparticles (silver, copper and zinc oxide nanoparticles) were employed as antimicrobial agents. X-ray photoelectron spectroscopy (XPS) measurements have shown a positive chemical shift observed for Ag 3d 5/2 (at 368.1 eV) suggests that silver nanoparticles (AgNPs) are partly oxidized during the deposition. The surface chemistry and the antibacterial activity of the samples against Staphylococcus aureus and Escherichia coli were investigated and analyzed. It is shown that the samples loaded with nanoparticles of Ag and Cu and having the barrier layer of 10 nm characterized by almost 97% of bacterial reduction whereas the samples with ZnO nanoparticles provide 86% reduction of Staphylococcus aureus. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  19. Atmospheric Pressure Plasma: A High-Performance Tool for the Efficient Removal of Biofilms

    Science.gov (United States)

    Fricke, Katja; Koban, Ina; Tresp, Helena; Jablonowski, Lukasz; Schröder, Karsten; Kramer, Axel; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Kocher, Thomas

    2012-01-01

    Introduction The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents. Method In this study a Candida albicans biofilm, formed on polystyrene (PS) wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture). The capability of plasma-assisted biofilm removal was assessed by microscopic imaging. Results The Candida albicans biofilm, with a thickness of 10 to 20 µm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy. PMID:22880025

  20. Multi-electrodes Atmospheric Pressure Plasma Jet Aiming Bio-applications

    Science.gov (United States)

    Han, Jeon G.; Sahu, B. B.; Shin, K. S.; Lee, J. S.; Hori, M.

    2015-09-01

    For the recent advancement in the field of plasma medicine, there is growing demand for the atmospheric-pressure plasma (APP) jet sources with desired plasma characteristics. In this study, a stable non-thermal low-voltage APP jet device was designed and developed for optical and electrical characterizations. The jet was operated at very low frequency in the range 10-40 KHz, which enabled the generation of low power (~ 7W) plasma with a plasma column diameter of about 5 mm. The jet has a visible radial diameter of approximately 10 mm. Optical emission spectroscopy was used as a diagnostic tool to investigate the generation of plasmas and radical species. Discharge parameters are also measured to evaluate the different operating conditions. The gas temperature measured at the substrate location varies from 300 to 315 K for different gases where the electrical input power ranged from 1 to 7 W. The highly reactive species like OH, O, N2, N2 + and along with the trace of NO are characterized with respect to the different gas flow rate of Ar/He/O2/N2, applied voltages, duty cycles and frequencies to evaluate the capability of the APP jet for future bio-applications.

  1. Simulations of planar non-thermal plasma assisted ignition at atmospheric pressure

    KAUST Repository

    Casey, Tiernan A.

    2016-10-21

    The opportunity for ignition assistance by a pulsed applied voltage is investigated in a canonical one-dimensional configuration. An incipient ignition kernel, formed by localized energy deposition into a lean mixture of methane and air at atmospheric pressure, is subjected to sub-breakdown electric fields (E/N ≈ 100 Td) by a DC potential applied across the domain, resulting in non-thermal behavior of the plasma formed during the discharge. A two-fluid approach is employed to couple thermal neutrals and ions to the non-thermal electrons. A two-temperature plasma mechanism describing gas phase combustion, excitation of neutral species, and high-energy electron kinetics is employed to account for non-thermal effects. Charged species transported from the ignition zone drift rapidly through the domain, augmenting the magnitude of the electric field in the fresh gas during the pulse through a dynamic-electrode effect, which results in an increase in the energy of the electrons in the fresh mixture with increasing time. Enhanced fuel and oxidizer decomposition due to electron impact dissociation and interaction with excited neutrals generate a pool of radicals, mostly O and H, in the fresh gas ahead of the flame\\'s preheat zone. In the configuration considered, the effect of the nanosecond pulse is to increase the mass of fuel burned at equivalent times relative to the unsupported ignition through enhanced radical generation, resulting in an increased heat release rate in the immediate aftermath of the pulse.

  2. Effects of oxygen concentration on atmospheric pressure dielectric barrier discharge in Argon-Oxygen Mixture

    Science.gov (United States)

    Li, Xuechun; Li, Dian; Wang, Younian

    2016-09-01

    A dielectric barrier discharge (DBD) can generate a low-temperature plasma easily at atmospheric pressure and has been investigated for applications in trials in cancer therapy, sterilization, air pollution control, etc. It has been confirmed that reactive oxygen species (ROS) play a key role in the processes. In this work, we use a fluid model to simulate the plasma characteristics for DBD in argon-oxygen mixture. The effects of oxygen concentration on the plasma characteristics have been discussed. The evolution mechanism of ROS has been systematically analyzed. It was found that the ground state oxygen atoms and oxygen molecular ions are the dominated oxygen species under the considered oxygen concentrations. With the oxygen concentration increasing, the densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. Increasing the oxygen concentration, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode. Project supported by the National Natural Science Foundation of China (Grant No. 11175034).

  3. Computational investigations of streamers in a single bubble suspended in distilled water under atmospheric pressure conditions

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan

    2016-09-01

    We present a computational model of nanosecond streamers generated in helium bubbles immersed in distilled water at the atmospheric pressure conditions. The model is based on the self-consistent, multispecies and the continuum description of plasma and takes into account the presence of water vapor in the gas bubble for a more accurate description of the kinetics of the discharge. We find that the dynamic characteristics of the streamer discharge are completely different at low and high over voltages. We observe that the polarity of the trigger voltage has a substantial effect on initiation, transition and evolution stages of streamers with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages due to the presence of multiple streamers. We also find that the presence of water vapor significantly influences the distribution of the dominant species in the streamer trail and has a profound effect on the flux of the dominant species to the bubble wall. The research reported in this publication was supported by Competitive Research Funding from King Abdullah University of Science and Technology (KAUST).

  4. Nitrogen-doped twisted graphene grown on copper by atmospheric pressure CVD from a decane precursor

    Directory of Open Access Journals (Sweden)

    Ivan V. Komissarov

    2017-01-01

    Full Text Available We present Raman studies of graphene films grown on copper foil by atmospheric pressure CVD with n-decane as a precursor, a mixture of nitrogen and hydrogen as the carrier gas, under different hydrogen flow rates. A novel approach for the processing of the Raman spectroscopy data was employed. It was found that in particular cases, the various parameters of the Raman spectra can be assigned to fractions of the films with different thicknesses. In particular, such quantities as the full width at half maximum of the 2D peak and the position of the 2D graphene band were successfully applied for the elaborated approach. Both the G- and 2D-band positions of single layer fractions were blue-shifted, which could be associated with the nitrogen doping of studied films. The XPS study revealed the characteristics of incorporated nitrogen, which was found to have a binding energy around 402 eV. Moreover, based on the statistical analysis of spectral parameters and the observation of a G-resonance, the twisted nature of the double-layer fraction of graphene grown with a lower hydrogen feeding rate was demonstrated. The impact of the varied hydrogen flow rate on the structural properties of graphene and the nitrogen concentration is also discussed.

  5. Nitrogen-doped twisted graphene grown on copper by atmospheric pressure CVD from a decane precursor.

    Science.gov (United States)

    Komissarov, Ivan V; Kovalchuk, Nikolai G; Labunov, Vladimir A; Girel, Ksenia V; Korolik, Olga V; Tivanov, Mikhail S; Lazauskas, Algirdas; Andrulevičius, Mindaugas; Tamulevičius, Tomas; Grigaliūnas, Viktoras; Meškinis, Šarunas; Tamulevičius, Sigitas; Prischepa, Serghej L

    2017-01-01

    We present Raman studies of graphene films grown on copper foil by atmospheric pressure CVD with n-decane as a precursor, a mixture of nitrogen and hydrogen as the carrier gas, under different hydrogen flow rates. A novel approach for the processing of the Raman spectroscopy data was employed. It was found that in particular cases, the various parameters of the Raman spectra can be assigned to fractions of the films with different thicknesses. In particular, such quantities as the full width at half maximum of the 2D peak and the position of the 2D graphene band were successfully applied for the elaborated approach. Both the G- and 2D-band positions of single layer fractions were blue-shifted, which could be associated with the nitrogen doping of studied films. The XPS study revealed the characteristics of incorporated nitrogen, which was found to have a binding energy around 402 eV. Moreover, based on the statistical analysis of spectral parameters and the observation of a G-resonance, the twisted nature of the double-layer fraction of graphene grown with a lower hydrogen feeding rate was demonstrated. The impact of the varied hydrogen flow rate on the structural properties of graphene and the nitrogen concentration is also discussed.

  6. Atmospheric pressure plasma: a high-performance tool for the efficient removal of biofilms.

    Directory of Open Access Journals (Sweden)

    Katja Fricke

    Full Text Available INTRODUCTION: The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents. METHOD: In this study a Candida albicans biofilm, formed on polystyrene (PS wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture. The capability of plasma-assisted biofilm removal was assessed by microscopic imaging. RESULTS: The Candida albicans biofilm, with a thickness of 10 to 20 µm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy.

  7. Degradation of palm oil refinery wastewaters by non-thermal gliding arc discharge at atmospheric pressure.

    Science.gov (United States)

    Mountapmbeme-Kouotou, P; Laminsi, S; Acayanka, E; Brisset, J-L

    2013-07-01

    The gliding electric discharge in humid air is a source of activated species forming (e.g. (•)OH, (•)NO and their derivatives H2O2, ONO2H and NO3H) which are present in a non-thermal plasma at atmospheric pressure. These species are able to degrade organic pollutants in palm oil refinery wastewaters (PORW). The increase in acidity (pH decrease), conductivity and total dissolved solids (TDS) and the decrease in the total organic carbon (TOC) of PORW samples exposed to the discharge are reported. More than 50% TOC abatement is obtained for 15 min treatment in batch conditions with a laboratory reactor. The organic pollutants of PORW, i.e. mainly fatty acids are degraded according to a pseudo first-order reaction (k* = 0.06 min(-1)). Post discharge reactions are also observed after having switched off the discharge, which suggests that the pseudo first-order (k ≈ 0.05 min(-1)) degradation reactions should be attributed to the diffusion of soluble reactive species, e.g. H2O2 and ONOOH in the liquid target.

  8. Application of atmospheric-pressure argon plasma jet for bread mold decontamination

    Science.gov (United States)

    Thonglor, P.; Amnuaycheewa, P.

    2017-09-01

    Atmospheric-pressure argon plasma (APAP) is a promising non-thermal technology for microbial control and prevention minimally affecting quality of foods. Effect of APAP jet on the growth of bread molds, including two Aspergillus sp., Rhizopus stolonifer, and Penicillium roqueforti, isolated from white bread were investigated. The molds were isolated, verified, cultured to fully grown on potato dextrose agar (PDA), and subsequently treated with APAP jet using plasma generating power at 24 W for 5, 10, and 20 min, respectively. The inhibition of mold growth was investigated by comparing fungal dry weights and the effect on fungal cell structure was observed using compound light microscope. The results indicated that the 20-min treatment time is most effective in retarding the growth of the three bread molds. However, this level of generating power did not lead to destruction of the cellular structures for all the four fungi. Plasma generating power and treatment time are significant parameters determining the success of bread mold decontamination and further investigation on real bread matrix is needed.

  9. Improvement of wettability and absorbancy of textile using atmospheric pressure dielectric barrier discharge

    Directory of Open Access Journals (Sweden)

    Bhagirath Ghimire

    2017-08-01

    Full Text Available In this study, cotton textile samples, commonly used in making quilt covers were subjected to atmospheric pressure dielectric barrier discharge treatment to study their surface wettability and absorbancy. Samples were treated in the discharge using a rotatory mechanism and the effects of plasma treatment were examined by contact angle measurement and weight measurement. Air plasma treatment was successful in incorporating hydrophilic functional groups on the textile surface due to which wettability as well as absorbancy immediately after the treatment were highly improved. Effects of plasma treatment started to appear only after 20 cycles (9 mins and got saturated after 24 cycles (10.8 mins of treatment. The contact angle reduced from 137 ° (untreated sample to a value less than 30 ° while absorbancy increased by more than two times as compared to untreated sample. Also, the aging behavior of the plasma treated samples were studied for about a week after plasma treatment. It was observed that the induced oxygen containing groups re-oriented into the bulk of the material during their storage in the environment due to which initial properties of the samples recovered gradually. Our results indicate that low temperature plasma can be successfully applied to modify the properties of textiles and textile industries could utilize this by standardization.

  10. Oxidative modification and electrochemical inactivation of Escherichia coli upon cold atmospheric pressure plasma exposure.

    Directory of Open Access Journals (Sweden)

    Marlène Dezest

    Full Text Available Cold atmospheric pressure plasmas (CAPPs are known to have bactericidal effects but the mechanism of their interaction with microorganisms remains poorly understood. In this study the bacteria Escherichia coli were used as a model and were exposed to CAPPs. Different gas compositions, helium with or without adjunctions of nitrogen or oxygen, were used. Our results indicated that CAPP induced bacterial death at decontamination levels depend on the duration, post-treatment storage and the gas mixture composition used for the treatment. The plasma containing O2 in the feeding gas was the most aggressive and showed faster bactericidal effects. Structural modifications of treated bacteria were observed, especially significant was membrane leakage and morphological changes. Oxidative stress caused by plasma treatment led to significant damage of E. coli. Biochemical analyses of bacterial macromolecules indicated massive intracellular protein oxidation. However, reactive oxygen and nitrogen species (RONS are not the only actors involved in E. coli's death, electrical field and charged particles could play a significant role especially for He-O2 CAPP.

  11. Cold atmospheric pressure plasma and decontamination. Can it contribute to preventing hospital-acquired infections?

    Science.gov (United States)

    O'Connor, N; Cahill, O; Daniels, S; Galvin, S; Humphreys, H

    2014-10-01

    Healthcare-associated infections (HCAIs) affect ∼4.5 million patients in Europe alone annually. With the ever-increasing number of 'multi-resistant' micro-organisms, alternative and more effective methods of environmental decontamination are being sought as an important component of infection prevention and control. One of these is the use of cold atmospheric pressure plasma (CAPP) systems with clinical applications in healthcare facilities. CAPPs have been shown to demonstrate antimicrobial, antifungal and antiviral properties and have been adopted for other uses in clinical medicine over the past decade. CAPPs vary in their physical and chemical nature depending on the plasma-generating mechanism (e.g. plasma jet, dielectric barrier discharge, etc.). CAPP systems produce a 'cocktail' of species including positive and negative ions, reactive atoms and molecules (e.g. atomic oxygen, ozone, superoxide and oxides of nitrogen), intense electric fields, and ultraviolet radiation (UV). The effects of these ions have been studied on micro-organisms, skin, blood, and DNA; thus, a range of possible applications of CAPPs has been identified, including surface decontamination, wound healing, biofilm removal, and even cancer therapy. Here we evaluate plasma devices, their applications, mode of action and their potential role specifically in combating HCAIs on clinical surfaces. Copyright © 2014 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  12. Atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for complex thiophenic mixture analysis

    KAUST Repository

    Hourani, Nadim

    2013-10-01

    Rationale Polycyclic aromatic sulfur heterocycles (PASHs) are detrimental species for refining processes in petroleum industry. Current mass spectrometric Methods that determine their composition are often preceded by derivatization and dopant addition approaches. Different ionization Methods have different impact on the molecular assignment of complex PASHs. The analysis of such species under atmospheric pressure chemical ionization (APCI) is still considered limited due to uncontrolled ion generation with low- and high-mass PASHs. Methods The ionization behavior of a model mixture of five selected PASH standards was investigated using an APCI source with nitrogen as the reagent gas. A complex thiophenic fraction was separated from a vacuum gas oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same ionization pattern was observed for the real thiophenic sample. It was found that S1 class species were the major sulfur-containing species found in the VGO sample. These species indicated the presence of alkylated benzothiophenic (BT), dibenzothiophenic (DBT) and benzonaphthothiophenic (BNT) series that were detected by APCI-FTICR MS. CONCLUSIONS This study provides an established APCI-FTICR MS method for the analysis of complex PASHs. PASHs were detected without using any derivatization and without fragmentation. The method can be used for the analysis of S-containing crude oil samples. © 2013 John Wiley & Sons, Ltd.

  13. Reduction in lateral lipid mobility of lipid bilayer membrane by atmospheric pressure plasma irradiation

    Science.gov (United States)

    Suda, Yoshiyuki; Tero, Ryugo; Yamashita, Ryuma; Yusa, Kota; Takikawa, Hirofumi

    2016-03-01

    Plasma medicine is an emerging research field in which various applications of electrical discharge, especially in the form of nonequilibrium plasma at atmospheric pressure, are examined, for example, the application of plasma to biological targets for various purposes such as selective killing of tumor cells and blood stanching. We have focused on the behavior of an artificial cell membrane system at the solid-liquid interface. To evaluate the lateral lipid mobility, we measured the diffusion coefficient of the supported lipid bilayer (SLB) composed of dioleoylphosphatidylcholine with fluorescence recovery after photobleaching by confocal laser scanning microscopy. It was found that the diffusion coefficient was decreased by plasma irradiation and that the diffusion coefficient decreasing rate proceeded with increasing plasma power. We investigated the effects of stimulation with an equilibrium chemical, H2O2, on the SLB and confirmed that the diffusion coefficient did not change at least up to a H2O2 concentration of 5 mM. These results indicate that transient active species generated by plasma play critical roles in the reduction in SLB fluidity. The effects of the two generated major oxidized lipid species, hydroxyl- or hydroperoxy-phosphatidylcholine (PC) and acyl-chain-truncated PCs terminated with aldehyde or carboxyl group, on lateral lipid mobility are discussed.

  14. Cavity-enhanced absorption spectroscopy to characterize atmospheric pressure plasma jets

    Science.gov (United States)

    van Helden, Jean-Pierre; Nave, Andy; Reuter, Stephan; Roepcke, Juergen; Gianella, Michele; Ritchie, Grant

    2016-09-01

    Non-equilibrium atmospheric pressure plasma jets gain more and more interest as their technological applications increase in diverse fields such as material processing and plasma medicine. Hence, it is essential to diagnose the fluxes of the species generated by these plasma sources to identify relevant fundamental processes and to improve process efficiency. Especially for a comprehensive understanding of the kinetics of the transient species involved, high precision measurements of reactive molecular precursors, free radicals and to identify of any short lived species are of crucial importance. However, the detection of transient species in these type of plasmas poses a challenge for diagnostic techniques as the plasmas typically have small dimensions and high density gradients in space and time. We have overcome these limitations by using cavity-enhanced absorption spectroscopy (CEAS). In this contribution, the latest results concerning the detection of transient species in two types of plasma jets employing CEAS in the near- and mid-infrared spectral range will be presented. We will show that with these methods spatially resolved investigations of concentrations in the mm sized effluent of the plasma jet can be achieved.

  15. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [College of Material and Textile Engineering, Jiaxing University, Jiaxing 314033 (China); Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Manolache, Sorin [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); US Forest Products Laboratory, Madison, WI 53726 (United States); Qiu, Yiping, E-mail: ypqiu@dhu.edu.cn [College of Textiles, Donghua University, Shanghai 201620 (China); Sarmadi, Majid, E-mail: majidsar@wisc.edu [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2016-02-28

    Graphical abstract: - Highlights: • The continuous ethanol flow technique can successfully modify ramie fiber surface with an increase in IFSS value up to 50%. • Response surface methodology was applied to design the plasma treatment parameters for ramie fiber modification. • The ethanol flow rate was the most influential treatment parameter in plasma modification process. - Abstract: In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  16. Molecular Effects of Atmospheric Pressure Plasma Jet on the Double-Stranded DNA

    Directory of Open Access Journals (Sweden)

    Abasalt Hosseinzadeh Colagar

    2017-03-01

    Full Text Available Introduction The aim of this study was toinvestigate the sterilization potential of atmospheric pressure plasma jet (APPJ and interactions of this technology with double-stranded DNA using the polymerase chain reaction (PCR and single-strand conformation polymorphism (SSCP techniques. Materials and Methods The plasma jet was produced through a high voltage sinusoidal power supplyusing a mixture of argon and oxygen gases with theflow rate of 1 L/min. Escherichia coli cells and double-stranded DNA (dsDNA fragments were amplified by T7 universal primer through the PCR technique and treated with argon/oxygen APPJ at different exposure times. The data were analyzed by the agarose and polyacrylamide gel electrophoresis, SSCP and renewed PCR techniques. Results According to the results of the study, the APPJ could serve as an effective instrument for sterilization at > 30 sec discharge. The destruction of DNA was detectable by different techniques after 120 sec from APPJ discharge. Conclusion Our findings revealed that the active species of plasma can lead to cell death. These species may break or nick the dsDNA, exchange DNA nucleotides, and lead to transition and transversion mutations. These mutagenesis effects of APPJ might be the reason of microorganism cell death after the treatment in addition to other destructive effects of APPJ on macromolecules.

  17. Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions

    Science.gov (United States)

    Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

    2017-07-01

    Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO3) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO3-nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO3) was produced in the flame. The HNO3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO3 showed the strongest affinity to histidine and formed (Mhistidine-H+HNO3)- complex ions, whereas some amino acids did not react with HNO3 at all. Reactions between HNO3 and histidine residues in AI and AII resulted in the formation of dominant [MAI-H+(HNO3)]- and [MAII-H+(HNO3)]- ions. Results from analyses of AAs and insulin indicated that HNO3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO3)n]3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins.

  18. Effect of sheath gas in atmospheric-pressure plasma jet for potato sprouting suppression

    Science.gov (United States)

    Nishiyama, S.; Monma, M.; Sasaki, K.

    2016-09-01

    Recently, low-temperature atmospheric-pressure plasma jets (APPJs) attract much interest for medical and agricultural applications. We try to apply APPJs for the suppression of potato sprouting in the long-term storage. In this study, we investigated the effect of sheath gas in APPJ on the suppression efficiency of the potato sprouting. Our APPJ was composed of an insulated thin wire electrode, a glass tube, a grounded electrode which was wound on the glass tube, and a sheath gas nozzle which was attached at the end of the glass tube. The wire electrode was connected to a rectangular-waveform power supply at a frequency of 3 kHz and a voltage of +/- 7 kV. Helium was fed through the glass tube, while we tested dry nitrogen, humid nitrogen, and oxygen as the sheath gas. Eyes of potatoes were irradiated by APPJ for 60 seconds. The sprouting probability was evaluated at two weeks after the plasma irradiation. The sprouting probability was 28% when we employed no sheath gases, whereas an improved probability of 10% was obtained when we applied dry nitrogen as the sheath gas. Optical emission spectroscopy was carried out to diagnose the plasma jet. It was suggested that reactive species originated from nitrogen worked for the efficient suppression of the potato sprouting.

  19. Syngas production from tar reforming by microwave plasma jet at atmospheric pressure: power supplied influence

    Science.gov (United States)

    de Souza Medeiros, Henrique; Justiniano, Lucas S.; Gomes, Marcelo P.; Soares da Silva Sobrinho, Argemiro; Petraconi Filho, Gilberto

    2013-09-01

    Now a day, scientific community is searching for new fuels able to replace fossil fuels with economic and environment gains and biofuel play a relevant rule, mainly for the transport sector. A major process to obtaining such type of renewable resource is biomass gasification. This process has as product a gas mixture containing CO, CH4, and H2 which is named synthesis gas (syngas). However, an undesirable high molecular organic species denominated tar are also produced in this process which must be removed. In this work, results of syngas production via tar reforming in the atmospheric pressure microwave discharge having as parameter the power supply. Argon, (argon + ethanol), and (argon + tar solution) plasma jet were produced by different values of power supplied (from 0.5 KW to 1.5 KW). The plasma compounds were investigated by optical spectroscopy to each power and gas composition. The main species observed in the spectrum are Ar, CN, OII, OIV, OH, H2, H(beta), CO2, CO, and SIII. This last one came from tar. The best value of the power applied to syngas production from tar reforming was verified between 1.0 KW and 1.2 KW. We thank the following institutions for financial support: CNPq, CAPES, and FAPESP.

  20. Environment-Dependent Radiation Damage in Atmospheric Pressure X-ray Spectroscopy.

    Science.gov (United States)

    Weatherup, Robert S; Wu, Cheng Hao; Escudero, Carlos; Pérez-Dieste, Virginia; Salmeron, Miquel B

    2017-09-18

    Atmospheric pressure X-ray spectroscopy techniques based on soft X-ray excitation can provide powerful interface-sensitive chemical information about a solid surface immersed in a gas or liquid environment. However, X-ray illumination of such dense phases can lead to the generation of considerable quantities of radical species by radiolysis. Soft X-ray absorption measurements of Cu films in both air and aqueous alkali halide solutions reveal that this can cause significant evolution of the Cu oxidation state. In air and NaOH (0.1 M) solutions, the Cu is oxidized toward CuO, while the addition of small amounts of CH3OH to the solution leads to reduction toward Cu2O. For Ni films in NaHCO3 solutions, the oxidation state of the surface is found to remain stable under X-ray illumination and can be electrochemically cycled between a reduced and oxidized state. We provide a consistent explanation for this behavior based on the products of X-ray-induced radiolysis in these different environments and highlight a number of general approaches that can mitigate radiolysis effects when performing operando X-ray measurements.

  1. Fourier transform infrared absorption spectroscopy characterization of gaseous atmospheric pressure plasmas with 2 mm spatial resolution

    Energy Technology Data Exchange (ETDEWEB)

    Laroche, G. [Laboratoire d' Ingenierie de Surface, Centre de Recherche sur les Materiaux Avances, Departement de genie des mines, de la metallurgie et des materiaux, Universite Laval, 1065, avenue de la Medecine, Quebec G1V 0A6 (Canada); Centre de recherche du CHUQ, Hopital St Francois d' Assise, 10, rue de l' Espinay, local E0-165, Quebec G1L 3L5 (Canada); Vallade, J. [Laboratoire Procedes, Materiaux et Energie Solaire, PROMES, CNRS, Technosud, Rambla de la Thermodynamique, F-66100 Perpignan (France); Agence de l' environnement et de la Ma Latin-Small-Letter-Dotless-I -carettrise de l' Energie, 20, avenue du Gresille, BP 90406, F-49004 Angers Cedex 01 (France); Bazinette, R.; Hernandez, E.; Hernandez, G.; Massines, F. [Laboratoire Procedes, Materiaux et Energie Solaire, PROMES, CNRS, Technosud, Rambla de la Thermodynamique, F-66100 Perpignan (France); Nijnatten, P. van [OMT Solutions bv, High Tech Campus 9, 5656AE Eindhoven (Netherlands)

    2012-10-15

    This paper describes an optical setup built to record Fourier transform infrared (FTIR) absorption spectra in an atmospheric pressure plasma with a spatial resolution of 2 mm. The overall system consisted of three basic parts: (1) optical components located within the FTIR sample compartment, making it possible to define the size of the infrared beam (2 mm Multiplication-Sign 2 mm over a path length of 50 mm) imaged at the site of the plasma by (2) an optical interface positioned between the spectrometer and the plasma reactor. Once through the plasma region, (3) a retro-reflector module, located behind the plasma reactor, redirected the infrared beam coincident to the incident path up to a 45 Degree-Sign beamsplitter to reflect the beam toward a narrow-band mercury-cadmium-telluride detector. The antireflective plasma-coating experiments performed with ammonia and silane demonstrated that it was possible to quantify 42 and 2 ppm of these species in argon, respectively. In the case of ammonia, this was approximately three times less than this gas concentration typically used in plasma coating experiments while the silane limit of quantification was 35 times lower. Moreover, 70% of the incoming infrared radiation was focused within a 2 mm width at the site of the plasma, in reasonable agreement with the expected spatial resolution. The possibility of reaching this spatial resolution thus enabled us to measure the gaseous precursor consumption as a function of their residence time in the plasma.

  2. Measurement of hydroxyl radical density generated from the atmospheric pressure bioplasma jet

    Science.gov (United States)

    Hong, Y. J.; Nam, C. J.; Song, K. B.; Cho, G. S.; Uhm, H. S.; Choi, D. I.; Choi, E. H.

    2012-03-01

    Atmospheric pressure bioplasmas are being used in a variety of bio-medical and material processing applications, surface modifications of polymers. This plasma can generate the various kinds of radicals when it contacs with the water. Especially, hydroxyl radical species have very important role in the biological and chemical decontamination of media in this situation. It is very important to investigate the hydroxyl radical density in needle-typed plasma jet since it plays a crucial role in interaction between the living body and plasma. We have generated the needle-typed plasma jet bombarding the water surface by using an Ar gas flow and investigated the emission lines by OES (optical emission spectroscopy). It is noted that the electron temperature and plasma density are measured to be about 1.7 eV and 3.4 × 1012 cm-3, respectively, under Ar gas flow ranged from 80 to 300 sccm (standard cubic centimeter per minute) in this experiment. The hydroxyl radical density has also been investigated and measured to be maximum value of 2.6 × 1015 cm-3 for the gas flow rate of 150 sccm in the needle-typed plasma jet by the ultraviolet optical absorption spectroscopy.

  3. Nanosecond Repetitively Pulsed Discharges in Air at Atmospheric Pressure -- Experiment and Theory of Regime Transitions

    Science.gov (United States)

    Pai, David; Lacoste, Deanna; Laux, Christophe

    2009-10-01

    In atmospheric pressure air preheated from 300 to 1000 K, the Nanosecond Repetitively Pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and inter-electrode gap distance) of each discharge regime. Notably, there is a minimum gap distance for the existence of the glow regime that increases with decreasing gas temperature. A theory is developed to describe the Corona-to-Glow (C-G) and Glow-to-Spark (G-S) transitions for NRP discharges. The C-G transition is shown to depend on the Avalanche-to-Streamer Transition (AST) as well as the electric field strength in the positive column. The G-S transition is due to the thermal ionization instability. The minimum gap distance for the existence of the glow regime can be understood by considering that the applied voltage of the AST must be lower than that of the thermal ionization instability. This is a previously unknown criterion for generating glow discharges, as it does not correspond to the Paschen minimum or to the Meek-Raether criterion.

  4. Studying Townsend and glow modes in an atmospheric-pressure DBD using mass spectrometry

    Science.gov (United States)

    McKay, Kirsty; Donaghy, David; He, Feng; Bradley, James W.

    2018-01-01

    Ambient molecular beam mass spectrometry has been employed to examine the effects of the mode of operation and the excitation waveform on the ionic content of a helium-based atmospheric-pressure parallel plate dielectric barrier discharge. By applying 10 kHz microsecond voltage pulses with a nanosecond rise times and 10 kHz sinusoidal voltage waveforms, distinctly different glow and Townsend modes were produced, respectively. Results showed a significant difference in the dominant ion species between the two modes. In the Townsend mode, molecular oxygen ions, atomic oxygen anions and nitric oxide anions are the most abundant species, however, in the glow mode water clusters ions and hydrated nitric oxygen anions dominate. Several hypotheses are put forward to explain these differences, including low electron densities and energies in the Townsend mode, more efficient ionization of water molecules through penning ionization and charge exchange with other species in glow mode, and large temperature gradients due to the pulsed nature of the glow mode, leading to more favorable conditions for cluster formation.

  5. Simulation for spatio-temporal variation of chemically active species in an atmospheric pressure streamer discharge.

    Science.gov (United States)

    Komuro, Atsushi; Takaahshi, Kazunori; Ando, Akira

    2016-09-01

    Spatiotemporal variation of radical density in an atmospheric pressure plasma discharge has been investigated by two-dimensional numerical simulation. Behaviors of radicals are characterized by four areas as ``Hot anode region'', ``Secondary streamer region'', ``Primary streamer region'', and ``Near-cathode region''. Although the reduced electric field in ``Hot anode region'' is relatively high, the gas temperature also increases and the ozone destruction process proceed. On the other hand, in ``Near-cathode region'', the high-energy radicals such as N(4S) is effectively produced because the instantaneous value of reduced electric field is high. Behaiviour of OH is also investigated. The results show that OH is effectively produced in ``Secondary streamer region'' and is not effective in ``Hot anode region''. This is because the reduced electric filed in ``Secondary streamer region'' is sufficiently high for the dissociation of H2O by O(D) and N2(a) and the gas temperature in ``Hot anode region'' is too high for the production of OH.

  6. Influence of atmospheric pressure low-temperature plasma treatment on the shear bond strength between zirconia and resin cement.

    Science.gov (United States)

    Ito, Yuki; Okawa, Takahisa; Fukumoto, Takahiro; Tsurumi, Akiko; Tatsuta, Mitsuhiro; Fujii, Takamasa; Tanaka, Junko; Tanaka, Masahiro

    2016-10-01

    Zirconia exhibits excellent strength and high biocompatibility in technological applications and it is has therefore been investigated for clinical applications and research. Before setting prostheses, a crown prosthesis inner surface is sandblasted with alumina to remove contaminants and form small cavities. This alumina sandblasting causes stress-induced phase transition of zirconia. Atmospheric-pressure low-temperature plasma has been applied in the dental industry, particularly for adhesives, as a surface treatment to activate the surface energy and remove contaminants. The purpose of this study was to examine the influence of atmospheric-pressure low-temperature plasma treatment on the shear bond strength between zirconia and adhesive resin cement. The surface treatment method was classified into three groups: untreated (Cont group), alumina sandblast treatment (Sb group), and atmospheric-pressure low-temperature plasma treatment (Ps group). Adhesive resin cement was applied to stainless steel and bonded to zirconia. Shear adhesion tests were performed after complete hardening of the cement. Multiple comparisons were performed using a one-way analysis of variance and the Bonferroni method. X-ray diffractometry was used to examine the change in zirconia crystal structure. Statistically significant differences were noted between the control and Sb groups and between the control and Ps groups. In contrast, no statistically significant differences were noted for the Ps and Sb bond strength. Atmospheric-pressure low-temperature plasma treatment did not affect the zirconia crystal structure. Atmospheric-pressure low-temperature plasma treatment improves the bonding strength of adhesive resin cement as effectively as alumina sandblasting, and does not alter the zirconia crystal structure. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  7. Investigation of microplasma discharge in sea water for optical emission spectroscopy

    Science.gov (United States)

    Gamaleev, Vladislav; Okamura, Yo; Kitamura, Kensuke; Hashimoto, Yusuke; Oh, Jun-Seok; Furuta, Hiroshi; Hatta, Akimitsu

    2016-07-01

    Microplasma discharge in sea water for optical emission spectroscopy was investigated using a needle-to-plane electrode system. The electrodes of a Pd needle and a Pt plate were placed with a gap of 25 µm in typical artificial sea water or locally sampled natural deep sea water. A pulse current source, consisting of a MOSFET switch, a capacitor, an inductor and the resistance of the sea water between the electrodes, was used. The circuit parameters were optimized to decrease the breakdown voltage and the spark duration to suppress erosion of the electrodes. Using a microgap configuration, spark discharges were reproducibly ignited in the highly conductive sea water at low breakdown voltages. The ignition of spark discharges required not only a critical voltage sufficient for breakdown, but also a critical energy for preheating of the sea water, sufficient for bubble formation. The possibility of using optical emission spectroscopy of microplasma in water is shown for identifying elemental composition of sea water.

  8. A comparative summary on streamers of positive corona discharges in water and atmospheric pressure gases

    Science.gov (United States)

    Tachibana, Kunihide; Motomura, Hideki

    2015-07-01

    From an intention of summarizing present understandings of positive corona discharges in water and atmospheric pressure gases, we tried to observe streamers in those media by reproducing and complementing previously reported results under a common experimental setup. We used a point-to-plane electrode configuration with different combinations of electrode gap (7 and 19 mm length) and pulsed power sources (0.25 and 2.5 ɛs duration). The general features of streamers were similar and the streamer-to-spark transition was also observed in both the media. However, in the details large differences were observed due to inherent nature of the media. The measured propagation speed of streamers in water of 0.035 × 106 ms-1 was much smaller than the speed in gases (air, N2 and Ar) from 0.4 to 1.1 × 106 ms-1 depending on species. In He the discharge looked glow-like and no streamer was observed. The other characteristics of streamers in gases, such as inception voltage, number of branches and thickness did also depend on the species. The thickness and the length of streamers in water were smaller than those in gases. From the volumetric expansion of a streamer in water after the discharge, the molecular density within the streamer medium was estimated to be rarefied from the density of water by about an order of magnitude in the active discharge phase. We derived also the electron density from the analysis of Stark broadened spectral lines of H and O atoms on the order of 1025 m-3 at the earlier time of the streamer propagation. The analyzed background blackbody radiation, rotational temperature of OH band emission and population density of Cu atomic lines yielded a consistent temperature of the streamer medium between 7000 and 10 000 K. Using the present data with a combination of the analysis of static electric field and previously reported results, we discuss the reason for the relatively low streamer inception voltage in water as compared to the large difference in the

  9. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

    2006-11-01

    Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are

  10. Fundamentals of ambient metastable-induced chemical ionization mass spectrometry and atmospheric pressure ion mobility spectrometry

    Science.gov (United States)

    Harris, Glenn A.

    Molecular ionization is owed much of its development from the early implementation of electron ionization (EI). Although dramatically increasing the library of compounds discovered, an inherent problem with EI was the low abundance of molecular ions detected due to high fragmentation leading to the difficult task of the correct chemical identification after mass spectrometry (MS). These problems stimulated the research into new ionization methods which sought to "soften" the ionization process. In the late 1980s the advancements of ionization techniques was thought to have reached its pinnacle with both electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Both ionization techniques allowed for "soft" ionization of large molecular weight and/or labile compounds for intact characterization by MS. Albeit pervasive, neither ESI nor MALDI can be viewed as "magic bullet" ionization techniques. Both techniques require sample preparation which often included native sample destruction, and operation of these techniques took place in sealed enclosures and often, reduced pressure conditions. New open-air ionization techniques termed "ambient MS" enable direct analysis of samples of various physical states, sizes and shapes. One particular technique named Direct Analysis In Real Time (DART) has been steadily growing as one of the ambient tools of choice to ionize small molecular weight (applications using DART as an ionization source, there have not been many studies investigating the fundamental properties of DART desorption and ionization mechanisms. The work presented in this thesis is aimed to provide in depth findings on the physicochemical phenomena during open-air DART desorption and ionization MS and current application developments. A review of recent ambient plasma-based desorption/ionization techniques for analytical MS is presented in Chapter 1. Chapter 2 presents the first investigations into the atmospheric pressure ion transport

  11. Effects of light on responses to low atmospheric pressure stunning in broilers.

    Science.gov (United States)

    Martin, J E; Christensen, K; Vizzier-Thaxton, Y; McKeegan, D E F

    2016-10-01

    Low atmospheric pressure stunning (LAPS) is a novel approach to poultry stunning involving the application of gradual decompression lasting 280 s according to a prescribed pressure curve. The aim of this study was to determine how behavioural, electroencephalogram (EEG) and electrocardiogram (ECG) responses to LAPS are influenced by illumination of the decompression chamber. A secondary aim was to examine responses to the decompression chamber without LAPS being applied, as such a "sham" control has been absent in previous studies. A two by two factorial design was employed, with LAPS/light, LAPS/dark, sham/light and sham/dark treatments (N = 20 per treatment). Broilers were exposed to each treatment in pairs, in each of which one bird was instrumented for recording EEG and ECG. Illumination was applied at 500 lx, and in sham treatments, birds were identically handled but remained undisturbed in the LAPS chamber without decompression for 280 s. Birds which underwent the sham treatment exhibited behaviours which were also observed in LAPS (e.g. sitting) while those exposed to LAPS exhibited hypoxia-related behaviours (e.g. ataxia, loss of posture). Behavioural latencies and durations were increased in the sham treatments, since the whole cycle time was available (in LAPS; birds were motionless by 186 s). Within the sham treatments, illumination increased active behaviour and darkness induced sleep, but slow-wave EEG was seen in both. The pattern of EEG response to LAPS (steep reduction in median frequency in the first 60 s and increased total power) was similar, irrespective of illumination, though birds in darkness had shorter latencies to loss of consciousness and isoelectric EEG. Cardiac responses to LAPS (pronounced bradycardia) closely matched those reported previously and were not affected by illumination. The effects of LAPS/sham treatment primarily reflected the presence/absence of hypoxia, while illumination affected activity/sleep levels in sham

  12. Homogenization of atmospheric pressure time series recorded at VLBI stations using a segmentation LASSO approach

    Science.gov (United States)

    Balidakis, Kyriakos; Heinkelmann, Robert; Lu, Cuixian; Soja, Benedikt; Karbon, Maria; Nilsson, Tobias; Glaser, Susanne; Andres Mora-Diaz, Julian; Anderson, James; Liu, Li; Raposo-Pulido, Virginia; Xu, Minghui; Schuh, Harald

    2015-04-01

    Time series of meteorological parameters recorded at VLBI (Very Long Baseline Interferometry) observatories allow us to realistically model and consequently to eliminate the atmosphere-induced effects in the VLBI products to a large extent. Nevertheless, this advantage of VLBI is not fully exploited since such information is contaminated with inconsistencies, such as uncertainties regarding the calibration and location of the meteorological sensors, outliers, missing data points, and breaks. It has been shown that such inconsistencies in meteorological data used for VLBI data analysis impose problems in the geodetic products (e.g vertical site position) and result in mistakes in geophysical interpretation. The aim of the procedure followed here is to optimally model the tropospheric delay and bending effects that are still the main sources of error in VLBI data analysis. In this study, the meteorological data recorded with sensors mounted in the vicinity of VLBI stations have been homogenized spanning the period from 1979 until today. In order to meet this objective, inhomogeneities were detected and adjusted using test results and metadata. Some of the approaches employed include Alexandersson's Standard Normal Homogeneity Test and an iterative procedure, of which the segmentation part is based on a dynamic programming algorithm and the functional part on a LASSO (Least Absolute Shrinkage and Selection Operator) estimator procedure. For the provision of reference time series that are necessary to apply the aforementioned methods, ECMWF's (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis surface data were employed. Special care was taken regarding the datum definition of this model. Due to the significant height difference between the VLBI antenna's reference point and the elevation included in geopotential fields of the specific numerical weather models, a hypsometric adjustment is applied using the absolute pressure level from the WMO

  13. Seasonal Variations of the Earth's Gravitational Field: An Analysis of Atmospheric Pressure, Ocean Tidal, and Surface Water Excitation

    Science.gov (United States)

    Dong, D,; Gross, R.S.; Dickey, J.

    1996-01-01

    Monthly mean gravitational field parameters (denoted here as C(sub even)) that represent linear combinations of the primarily even degree zonal spherical harmonic coefficients of the Earth's gravitational field have been recovered using LAGEOS I data and are compared with those derived from gridded global surface pressure data of the National meteorological center (NMC) spanning 1983-1992. The effect of equilibrium ocean tides and surface water variations are also considered. Atmospheric pressure and surface water fluctuations are shown to be the dominant cause of observed annual C(sub even) variations. Closure with observations is seen at the 1sigma level when atmospheric pressure, ocean tide and surface water effects are include. Equilibrium ocean tides are shown to be the main source of excitation at the semiannual period with closure at the 1sigma level seen when both atmospheric pressure and ocean tide effects are included. The inverted barometer (IB) case is shown to give the best agreement with the observation series. The potential of the observed C(sub even) variations for monitoring mass variations in the polar regions of the Earth and the effect of the land-ocean mask in the IB calculation are discussed.

  14. Aluminum metal surface cleaning and activation by atmospheric-pressure remote plasma

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz, J., E-mail: jmespadero@uco.es; Bravo, J.A.; Calzada, M.D.

    2017-06-15

    Highlights: • Atmospheric-pressure postdischarges have been applied on aluminium surfaces. • The outer hydrocarbon layer is reduced by the action of the postdischarge. • The treatment promotes the appearance of hydrophilic OH radicals in the surface. • Effectivity for distances up to 5 cm allows for treating irregular surfaces. • Ageing in air due to the disappearance of OH radicals has been reported. - Abstract: The use of the remote plasma (postdischarge) of argon and argon-nitrogen microwave plasmas for cleaning and activating the surface of metallic commercial aluminum samples has been studied. The influence of the nitrogen content and the distance between the treated samples and the end of the discharge on the hydrophilicity and the surface energy has been analyzed by means of the sessile drop technique and the Owens-Wendt method. A significant increase in the hydrophilicity has been noted in the treated samples, together with an increase in the surface energy from values around 37 mJ/m{sup 2} to 77 mJ/m{sup 2}. Such increase weakly depends on the nitrogen content of the discharge, and the effectivity of the treatment extends to distances up to 5 cm from the end of the discharge, much longer than those reported in other plasma-based treatments. The analysis of the treated samples using X-ray photoelectron spectroscopy reveals that such increase in the surface energy takes place due to a reduction of the carbon content and an increase in the amount of OH radicals in the surface. These radicals tend to disappear within 24–48 h after the treatment when the samples are stored in contact with ambient air, resulting in the ageing of the treated surface and a partial retrieval of the hydrophobicity of the surface.

  15. Influence of the Steam Addition on Premixed Methane Air Combustion at Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Mao Li

    2017-07-01

    Full Text Available Steam-diluted combustion in gas turbine systems is an effective approach to control pollutant emissions and improve the gas turbine efficiency. The primary purpose of the present research is to analyze the influence of steam dilution on the combustion stability, flame structures, and CO emissions of a swirl-stabilized gas turbine model combustor under atmospheric pressure conditions. The premixed methane/air/steam flame was investigated with three preheating temperatures (384 K/434 K/484 K and the equivalence ratio was varied from stoichiometric conditions to the flammability limits where the flame was physically blown out from the combustor. In order to represent the steam dilution intensity, the steam fraction Ω defined as the steam to air mass flow rate ratio was used in this work. Exhaust gases were sampled with a water-cooled emission probe which was mounted at the combustor exit. A 120 mm length quartz liner was used which enabled the flame visualization and optical measurement. Time-averaged CH chemiluminescence imaging was conducted to characterize the flame location and it was further analyzed with the inverse Abel transform method. Chemical kinetics calculation was conducted to support and analyze the experimental results. It was found that the LBO (lean blowout limits were increased with steam fraction. CH chemiluminescence imaging showed that with a high steam fraction, the flame length was elongated, but the flame structure was not altered. CO emissions were mapped as a function of the steam fraction, inlet air temperature, and equivalence ratios. Stable combustion with low CO emission can be achieved with an appropriate steam fraction operation range.

  16. Atmospheric Pressure Plasma Polymerization Synthesis and Characterization of Polyaniline Films Doped with and without Iodine

    Directory of Open Access Journals (Sweden)

    Choon-Sang Park

    2017-11-01

    Full Text Available Although polymerized aniline (polyaniline, PANI with and without iodine (I2 doping has already been extensively studied, little work has been done on the synthesis of PANI films using atmospheric pressure plasma (APP deposition. Therefore, this study characterized pure and I2-doped PANI films synthesized using an advanced APP polymerization system. The I2 doping was conducted ex-situ and using an I2 chamber method following the APP deposition. The pure and I2-doped PANI films were structurally analyzed using field emission scanning electron microscope (FE-SEM, atomic force microscope (AFM, X-ray Diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, X-ray photoelectron spectroscopy (XPS, and time of flight secondary ion mass spectrometry (ToF-SIMS studies. When increasing the I2 doping time, the plane and cross-sectional SEM images showed a decrease in the width and thickness of the PANI nanofibers, while the AFM results showed an increase in the roughness and grain size of the PANI films. Moreover, the FT-IR, XPS, and ToF-SIMS results showed an increase in the content of oxygen-containing functional groups and C=C double bonds, yet decrease in the C–N and C–H bonds when increasing the I2 doping time due to the reduction of hydrogen in the PANI films via the I2. To check the suitability of the conductive layer for polymer display applications, the resistance variations of the PANI films grown on the interdigitated electrode substrates were also examined according to the I2 doping time.

  17. Atmospheric Pressure Plasma Polymerization Synthesis and Characterization of Polyaniline Films Doped with and without Iodine.

    Science.gov (United States)

    Park, Choon-Sang; Jung, Eun Young; Kim, Dong Ha; Kim, Do Yeob; Lee, Hyung-Kun; Shin, Bhum Jae; Lee, Dong Ho; Tae, Heung-Sik

    2017-11-06

    Although polymerized aniline (polyaniline, PANI) with and without iodine (I₂) doping has already been extensively studied, little work has been done on the synthesis of PANI films using atmospheric pressure plasma (APP) deposition. Therefore, this study characterized pure and I₂-doped PANI films synthesized using an advanced APP polymerization system. The I₂ doping was conducted ex-situ and using an I₂ chamber method following the APP deposition. The pure and I₂-doped PANI films were structurally analyzed using field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and time of flight secondary ion mass spectrometry (ToF-SIMS) studies. When increasing the I₂ doping time, the plane and cross-sectional SEM images showed a decrease in the width and thickness of the PANI nanofibers, while the AFM results showed an increase in the roughness and grain size of the PANI films. Moreover, the FT-IR, XPS, and ToF-SIMS results showed an increase in the content of oxygen-containing functional groups and C=C double bonds, yet decrease in the C-N and C-H bonds when increasing the I₂ doping time due to the reduction of hydrogen in the PANI films via the I₂. To check the suitability of the conductive layer for polymer display applications, the resistance variations of the PANI films grown on the interdigitated electrode substrates were also examined according to the I₂ doping time.

  18. Lens epithelial cell response to atmospheric pressure plasma modified poly(methylmethacrylate) surfaces.

    Science.gov (United States)

    D'Sa, Raechelle A; Burke, George A; Meenan, Brian J

    2010-05-01

    Selective control of cellular response to polymeric biomaterials is an important consideration for many ocular implant applications. In particular, there is often a need to have one surface of an ophthalmic implant capable of promoting cell attachment while the other needs to be resistant to this effect. In this study, an atmospheric pressure dielectric barrier discharge (DBD) has been used to modify the surface region of poly(methyl methacrylate) (PMMA), a well established ocular biomaterial, with the aim of promoting a controlled response to human lens epithelial cells (LEC) cultured thereon. The DBD plasma discharge environment has also been employed to chemically graft a layer of poly(ethylene glycol) methyl ether methacrylate (PEGMA) onto the PMMA and the response to LEC likewise determined. Two different molecular weights of PEGMA, namely 1000 and 2000 MW were used in these experiments. The LEC response to DBD treated polystyrene (PS) samples has also been examined as a positive control and to help to further elucidate the nature of the modified surfaces. The LEC adhered and proliferated readily on the DBD treated PMMA and PS surfaces when compared to the pristine polymer samples which showed little or no cell response. The PMMA and PS surfaces that had been DBD grafted with the PEGMA(1000) layer were found to have some adhered cells. However, on closer inspection, these cells were clearly on the verge of detaching. In the case of the PEGMA(2000) grafted surfaces no cells were observed indicating that the higher molecular weight PEGMA has been able to attain a surface conformation that is capable of resisting cell attachment in vitro.

  19. Gas heating dynamics during leader inception in long air gaps at atmospheric pressure

    Science.gov (United States)

    Liu, Lipeng; Becerra, Marley

    2017-08-01

    The inception of leader discharges in long air gaps at atmospheric pressure is simulated with a thermo-hydrodynamic model and a detailed kinetic scheme for N2/O2/H2O mixtures. In order to investigate the effect of humidity, the kinetic scheme includes the most important reactions with the H2O molecule and its derivatives, resulting in a scheme with 45 species and 192 chemical reactions. The heating of a thin plasma channel in front of an anode electrode during the streamer to leader transition is evaluated with a detailed 1D radial model. The analysis includes the simulation of the corresponding streamer bursts, dark periods and aborted leaders that may occur prior to the inception of a propagating leader discharge. The simulations are performed using the time-varying discharge current in two laboratory discharge events of positive polarity reported in the literature as input. Excellent agreement between the simulated and the experimental time variation of the thermal radius for a 1 m rod-plate air gap discharge event reported in the literature has been found. The role of different energy transfer and loss mechanisms prior to the inception of a stable leader is also discussed. It is found that although a small percentage of water molecules can accelerate the vibrational-translational relaxation to some extent, this effect leads to a negligible temperature increase during the streamer-to-leader transition. It is also found that the gas temperature should significantly exceed 2000 K for the transition to lead to the inception of a propagating leader. Otherwise, the strong convection loss produced by the gas expansion during the transition causes a drop in the translational temperature below 2000 K, aborting the incepted leader. Furthermore, it is shown that the assumptions used by the widely-used model of Gallimberti do not hold when evaluating the streamer-to-leader transition.

  20. Structural and optical properties of CdO nanostructures prepared by atmospheric-pressure CVD

    Energy Technology Data Exchange (ETDEWEB)

    Terasako, T., E-mail: terasako.tomoaki.mz@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Fujiwara, T. [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Nakata, Y.; Yagi, M. [Kagawa National College of Technology, 551 Koda, Takuma-cho, Mitoyo 769-1192 (Japan); Shirakata, S. [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2013-01-01

    Cadmium oxide (CdO) nanostructures of various shapes were successfully grown on gold (Au) nanocolloid coated c-plane sapphire substrates by atmospheric-pressure CVD using Cd powder and H{sub 2}O as source materials. CdO nanorods (NRs) exhibited tapered shapes and the degree of the tapering became larger with increasing substrate temperature. One of the possible reasons for the tapering behavior is the competition between the axial growth due to the vapor–liquid–solid (VLS) mechanism and the radial growth due to the vapor–solid (VS) mechanism. The influence of the competition between the two different growth mechanisms was also confirmed on the appearance of “seaweed-like” NRs. Moreover, we cannot neglect the influence of the shrinkage of catalyst particles during the growth process on the tapering behavior. In addition, there is a possibility that the temporal evolution of catalyst particles, such as diffusion, splitting, migration and coalescence, contributes not only to the disappearance of catalyst particles on the tips of the NRs, resulting in the enhancement of the radial growth relative to the axial growth, but also to the formation of nanobelts (NBs) and nanotrees (NTs). Photoacoustic measurements revealed that the absorption edge shifts towards lower energies and the absorption band below the absorption edge becomes larger with increasing T{sub S}. This tendency may be due to the increase of intrinsic defects and/or the decrease in residual impurities. - Highlights: ► Various shapes of CdO nanostructures were grown by AP-CVD using Cd and H{sub 2}O. ► This diversity is due to the competition between VLS and VS mechanisms. ► The temporal evolution of Au catalyst particles also contributes to the diversity. ► Photoacoustic spectra were changed, depending on the substrate temperature. ► This is probably related to the intrinsic defects and/or residual impurities.

  1. Studies in graphene growth and processing using atmospheric pressure chemical vapor deposition

    Science.gov (United States)

    Merrell, Andrew Nephi

    This dissertation focuses on graphene, a promising two-dimensional, carbon material with many favorable electronic properties. The prospect of implementing graphene into a wide variety of potential device applications is enticing, but many factors stand in the way before this goal is realized. Atmospheric pressure chemical vapor deposition (APCVD) is a graphene production method that may be compatible with large-scale growth. Motivated by the need to more fully understand APCVD growth of graphene, a system is constructed, and several studies are carried out. Specifically, a detailed study is presented which involves the effects of hydrogen and contaminant oxygen in APCVD-grown graphene. The research shows that hydrogen is an important factor to control during the cooling stage of APCVD, as it has a direct effect on the formation of oxides on the copper foil (copper is used as the catalyst for graphene growth in APCVD). It is also determined that hydrogen, as well as the reaction chamber, play an important role in the formation of SiO2 nanoparticles, which accumulate on the copper surface during graphene growth. Methods for patterning and processing graphene are also explored in this dissertation, as such methods are crucial in the realization of graphene-based devices. The method of e-beam assisted metal deposition used in conjunction with masked-CVD growth is proposed as an effective alternative to conventional processing methods such as photolithography and electron-beam lithography. The proposed methods have several advantages, which pave the way for lowering graphene/metal contact resistance, and preserving the intrinsic properties of graphene during device fabrication.

  2. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    Energy Technology Data Exchange (ETDEWEB)

    Abuzairi, Tomy [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electrical Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424 (Indonesia); Okada, Mitsuru [Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Nagatsu, Masaaki, E-mail: nagatsu.masaaki@shizuoka.ac.jp [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan)

    2016-12-30

    Highlights: • Spatio-temporal behaviors of capillary APPJs are studied for various substrates. • Plasma irradiation area depended on the substrate conductivity and permittivity. • Surface irradiation area was significantly broadened in polymer-like substrate. • Effect of applying a substrate bias on the APPJ irradiation area was investigated. - Abstract: An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5–4.2 km/s and 2–7 × 10{sup 17} m{sup −3}. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from −900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  3. Cold atmospheric pressure plasma elimination of clinically important single- and mixed-species biofilms.

    Science.gov (United States)

    Modic, Martina; McLeod, Neil P; Sutton, J Mark; Walsh, James L

    2017-03-01

    Mixed-species biofilms reflect the natural environment of many pathogens in clinical settings and are highly resistant to disinfection methods. An indirect cold atmospheric-pressure air-plasma system was evaluated under two different discharge conditions for its ability to kill representative Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) pathogens. Plasma treatment of individual 24-h-old biofilms and mixed-species biofilms that contained additional species (Enterococcus faecalis and Klebsiella pneumoniae) was considered. Under plasma conditions that favoured the production of reactive nitrogen species (RNS), individual P. aeruginosa biofilms containing ca. 5.0 × 10(6) CFU were killed extremely rapidly, with no bacterial survival detected at 15 s of exposure. Staphylococcus aureus survived longer under these conditions, with no detectable growth after 60 s of exposure. In mixed-species biofilms, P. aeruginosa survived longer but all species were killed with no detectable growth at 60 s. Under plasma conditions that favoured the production of reactive oxygen species (ROS), P. aeruginosa showed increased survival, with the lower limit of detection reached by 120 s, and S. aureus was killed in a similar time frame. In the mixed-species model, bacterial kill was biphasic but all pathogens showed viable cells after 240 s of exposure, with P. aeruginosa showing significant survival (ca. 3.6 ± 0.6 × 10(6) CFU). Overall, this study shows the potential of indirect air plasma treatment to achieve significant bacterial kill, but highlights aspects that might affect performance against key pathogens, especially in real-life settings within mixed populations. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  4. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Begum, Asma [Independent University, Bangladesh, School of Engineering and Computer Science, Bashundhara, Dhaka (Bangladesh); Laroussi, Mounir [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, Virginia (United States); Pervez, Mohammad Rasel [Master Mind College, Department of Physics, Dhanmondi, Dhaka (Bangladesh)

    2013-06-15

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10{sup 11} cm{sup -3} and it reaches to the maximum of 10{sup 12} cm{sup -3}.

  5. Three distinct modes in a surface micro-discharge in atmospheric pressure He + N2 mixtures

    Science.gov (United States)

    Li, Dong; Liu, Dingxin; He, Tongtong; Li, Qiaosong; Wang, Xiaohua; Kong, Michael G.

    2015-12-01

    A surface micro-discharge in atmospheric pressure He + N2 mixtures is studied in this paper with an emphasis on the discharge modes. With the N2 admixture increasing from 0.1% to 20%, the discharge evolves from a spatially diffuse mode to a filamentary mode during positive half-cycles of the applied voltage. However during the negative half-cycles, an additional patterned mode emerges between the diffuse and the filamentary modes, which has not been reported before to exist in surface micro-discharges. In the diffuse and patterned modes, the plasmas cover almost the entirety of the mesh area during one cycle after plasma ignition in all mesh elements, and the discharge power increases linearly with the applied voltage. In contrast, plasma coverage of the mesh area is only partial in the filamentary mode and the plasma is more unstable with the discharge power increasing exponentially with the applied voltage. As the surface micro-discharge evolves through the three modes, the density of excited species changes significantly, for instance, the density of N2+(B) drops by ˜20-fold from [N2] = 0.2% to 20%. The N2+(B) is predicted to be generated mainly through successive processes of Penning ionization by helium metastables and electron-impact excitation of N2+(X), the latter is most responsible for the density decrease of N2+(B) because much more N2+(X) is converted to N4+(X) as the increase of N2 fraction. Also, the electron density and electron temperature decrease with the discharge mode transition.

  6. Conductive zinc oxide thin film coatings by combustion chemical vapour deposition at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Zunke, I., E-mail: iz@innovent-jena.de [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Heft, A. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Schäfer, P.; Haidu, F.; Lehmann, D. [Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Grünler, B.; Schimanski, A. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Zahn, D.R.T. [Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, 09126 Chemnitz (Germany)

    2013-04-01

    We have established a combustion chemical vapour deposition (C-CVD) system for the deposition of zinc oxide (ZnO) at atmospheric pressure. This C-CVD process has the advantage of a short exposure of the substrates to the flame. It is also potentially applicable as an inline coating system. Fundamental studies were performed on undoped ZnO. The specific resistivity of these layers strongly depends on the film thickness and decreases with increasing thickness. As the lowest resistivities, values of about 2.0 · 10{sup −1} Ωcm are achieved. Ultra-violet photoemission spectra show the valence band structure of the deposited ZnO. The work function and valence band edge were determined. UV–vis spectra were taken to investigate the transmission of the coated glass samples. From these spectra the band gap energy was obtained. Raman spectroscopy as well as infrared spectroscopy confirmed the presence of ordered ZnO crystallites. The X-ray diffraction verified this result and illustrates the hexagonal structure. In the mid-infrared range precursor deposits were detected for low substrate temperatures. - Highlights: ► Zinc oxide (ZnO) films are conductive in the range of 2.0 · 10{sup −1} Ωcm. ► X-ray diffraction, Raman and infrared spectroscopy indicate crystalline ZnO films. ► Precursor deposits were proved within the films for low growing temperatures. ► Band gap energy changes are achieved due to different growing temperatures.

  7. Main species and chemical pathways in cold atmospheric-pressure Ar + H2O plasmas

    Science.gov (United States)

    Liu, Dingxin; Sun, Bowen; Iza, Felipe; Xu, Dehui; Wang, Xiaohua; Rong, Mingzhe; Kong, Michael G.

    2017-04-01

    Cold atmospheric-pressure plasmas in Ar + H2O gas mixtures are a promising alternative to He + H2O plasmas as both can produce reactive oxygen species of relevance for many applications and argon is cheaper than helium. Although He + H2O plasmas have been the subject of multiple experimental and computational studies, Ar + H2O plasmas have received less attention. In this work we investigate the composition and chemical pathways in Ar + H2O plasmas by means of a global model that incorporates 57 species and 1228 chemical reactions. Water vapor concentrations from 1 ppm to saturation (32 000 ppm) are considered in the study and abrupt transitions in power dissipation channels, species densities and chemical pathways are found when the water concentration increases from 100 to 1000 ppm. In this region the plasma transitions from an electropositive discharge in which most power is coupled to electrons into an electronegative one in which most power is coupled to ions. While increasing electronegativity is also observed in He + H2O plasmas, in Ar + H2O plasmas the transition is more abrupt because Penning processes do not contribute to gas ionization and the changes in the electron energy distribution function and mean electron energy caused by the increasing water concentration result in electron-neutral excitation and ionization rates changing by many orders of magnitude in a relatively small range of water concentrations. Insights into the main chemical species and pathways governing the production and loss of electrons, O, OH, OH(A) and H2O2 are provided as part of the study.

  8. Afterglow chemistry of atmospheric-pressure helium-oxygen plasmas with humid air impurity

    Science.gov (United States)

    Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

    2014-04-01

    The formation of reactive species in the afterglow of a radio-frequency-driven atmospheric-pressure plasma in a fixed helium-oxygen feed gas mixture (He+0.5%O2) with humid air impurity (a few hundred ppm) is investigated by means of an extensive global plasma chemical kinetics model. As an original objective, we explore the effects of humid air impurity on the biologically relevant reactive species in an oxygen-dependent system. After a few milliseconds in the afterglow environment, the densities of atomic oxygen (O) decreases from 1015 to 1013 cm-3 and singlet delta molecular oxygen (O2(1D)) of the order of 1015 cm-3 decreases by a factor of two, while the ozone (O3) density increases from 1014 to 1015 cm-3. Electrons and oxygen ionic species, initially of the order of 1011 cm-3, recombine much faster on the time scale of some microseconds. The formation of atomic hydrogen (H), hydroxyl radical (OH), hydroperoxyl (HO2), hydrogen peroxide (H2O2), nitric oxide (NO) and nitric acid (HNO3) resulting from the humid air impurity as well as the influence on the afterglow chemistry is clarified with particular emphasis on the formation of dominant reactive oxygen species (ROS). The model suggests that the reactive species predominantly formed in the afterglow are major ROS O2(1D) and O3 (of the order of 1015 cm-3) and rather minor hydrogen- and nitrogen-based reactive species OH, H2O2, HNO3 and NO2/NO3, of which densities are comparable to the O-atom density (of the order of 1013 cm-3). Furthermore, the model quantitatively reproduces the experimental results of independent O and O3 density measurements.

  9. An added dimension: GC atmospheric pressure chemical ionization FTICR MS and the Athabasca oil sands.

    Science.gov (United States)

    Barrow, Mark P; Peru, Kerry M; Headley, John V

    2014-08-19

    The Athabasca oil sands industry, an alternative source of petroleum, uses large quantities of water during processing of the oil sands. In keeping with Canadian environmental policy, the processed water cannot be released to natural waters and is thus retained on-site in large tailings ponds. There is an increasing need for further development of analytical methods for environmental monitoring. The following details the first example of the application of gas chromatography atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FTICR MS) for the study of environmental samples from the Athabasca region of Canada. APCI offers the advantages of reduced fragmentation compared to other ionization methods and is also more amenable to compounds that are inaccessible by electrospray ionization. The combination of GC with ultrahigh resolution mass spectrometry can improve the characterization of complex mixtures where components cannot be resolved by GC alone. This, in turn, affords the ability to monitor extracted ion chromatograms for components of the same nominal mass and isomers in the complex mixtures. The proof of concept work described here is based upon the characterization of one oil sands process water sample and two groundwater samples in the area of oil sands activity. Using the new method, the Ox and OxS compound classes predominated, with OxS classes being particularly relevant to the oil sands industry. The potential to resolve retention times for individual components within the complex mixture, highlighting contributions from isomers, and to characterize retention time profiles for homologous series is shown, in addition to the ability to follow profiles of double bond equivalents and carbon number for a compound class as a function of retention time. The method is shown to be well-suited for environmental forensics.

  10. Desorption atmospheric pressure photoionization with polydimethylsiloxane as extraction phase and sample plate material

    Energy Technology Data Exchange (ETDEWEB)

    Vaikkinen, A. [Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FIN-00014 University of Helsinki (Finland); Kotiaho, T. [Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FIN-00014 University of Helsinki (Finland); Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland); Kostiainen, R. [Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FIN-00014 University of Helsinki (Finland); Kauppila, T.J., E-mail: tiina.kauppila@helsinki.fi [Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FIN-00014 University of Helsinki (Finland)

    2010-12-03

    Desorption atmospheric pressure photoionization (DAPPI) is an ambient ionization technique for mass spectrometry (MS) that can be used to ionize polar as well as neutral and completely non-polar analytes. In this study polydimethylsiloxane (PDMS) was used as a solid phase extraction sorbent for DAPPI-MS analysis. Pieces of PDMS polymer were soaked in an aqueous sample, where the analytes were sorbed from the sample solution to PDMS. After this, the extracted analytes were desorbed directly from the polymer by the hot DAPPI spray solvent plume, without an elution step. Swelling and extracting the PDMS with a cleaning solvent prior to extraction diminished the high background in the DAPPI mass spectrum caused by PDMS oligomers. Acetone, hexane, pentane, toluene, diisopropylamine and triethylamine were tested for this purpose. The amines were most efficient in reducing the PDMS background, but they also suppressed the signals of low proton affinity analytes. Toluene was chosen as the optimum cleaning solvent, since it reduced the PDMS background efficiently and gave intensive signals of most of the studied analytes. The effects of DAPPI spray solvents toluene, acetone and anisole on the PDMS background and the ionization of analytes were also compared and extraction conditions were optimized. Anisole gave a low background for native PDMS, but toluene ionized the widest range of analytes. Analysis of verapamil, testosterone and anthracene from purified, spiked wastewater was performed to demonstrate that the method is suited for in-situ analysis of water streams. In addition, urine spiked with several analytes was analyzed by the PDMS method and compared to the conventional DAPPI procedure, where sample droplets are applied on PMMA surface. With the PDMS method the background ion signals caused by the urine matrix were lower, the S/N ratios of analytes were 2-10 times higher, and testosterone, anthracene and benzo[a]pyrene that were not detected from PMMA in urine

  11. Atmospheric-Pressure Cold Plasma Induces Transcriptional Changes in Ex Vivo Human Corneas.

    Directory of Open Access Journals (Sweden)

    Umberto Rosani

    Full Text Available Atmospheric pressure cold plasma (APCP might be considered a novel tool for tissue disinfection in medicine since the active chemical species produced by low plasma doses, generated by ionizing helium gas in air, induces reactive oxygen species (ROS that kill microorganisms without substantially affecting human cells.In this study, we evaluated morphological and functional changes in human corneas exposed for 2 minutes (min to APCP and tested if the antioxidant n-acetyl l-cysteine (NAC was able to inhibit or prevent damage and cell death.Immunohistochemistry and western blotting analyses of corneal tissues collected at 6 hours (h post-APCP treatment demonstrated no morphological tissue changes, but a transient increased expression of OGG1 glycosylase that returned to control levels in 24 h. Transcriptome sequencing and quantitative real time PCR performed on different corneas revealed in the treated corneas many differentially expressed genes: namely, 256 and 304 genes showing expression changes greater than ± 2 folds in the absence and presence of NAC, respectively. At 6 h post-treatment, the most over-expressed gene categories suggested an active or enhanced cell functioning, with only a minority of genes specifically concerning oxidative DNA damage and repair showing slight over-expression values (<2 folds. Moreover, time-related expression analysis of eight genes up-regulated in the APCP-treated corneas overall demonstrated the return to control expression levels after 24 h.These findings of transient oxidative stress accompanied by wide-range transcriptome adjustments support the further development of APCP as an ocular disinfectant.

  12. Atmospheric pressure plasma jet for bacterial decontamination and property improvement of fruit and vegetable processing wastewater

    Science.gov (United States)

    Mohamed, Abdel-Aleam H.; Shariff, Samir M. Al; Ouf, Salama A.; Benghanem, Mohamed

    2016-05-01

    An atmospheric pressure plasma jet was tested for decontaminating and improving the characteristics of wastewater derived from blackberry, date palm, tomato and beetroot processing industries. The jet was generated by blowing argon gas through a cylindrical alumina tube while a high voltage was applied between two electrodes surrounding the tube. Oxygen gas was mixed with argon at the rate of 0.2% and the argon mass flow was fixed at 4.5 slm. Images show that the generated plasma jet penetrated the treated wastewater samples. Plasma emission spectra show the presence of O and OH radicals as well as excited molecular nitrogen and argon. Complete decontamination of wastewater derived from date palm and tomato processing was achieved after 120 and 150 s exposure to the plasma jet, respectively. The bacterial count of wastewater from blackberry and beetroot was reduced by 0.41 and 2.24 log10 colony-forming units (CFU) per ml, respectively, after 180 s. Escherichia coli was the most susceptible bacterial species to the cold plasma while Shigella boydii had the minimum susceptibility, recording 1.30 and 3.34 log10 CFU ml-1, respectively, as compared to the 7.00 log10 initial count. The chemical oxygen demands of wastewater were improved by 57.5-93.3% after 180 s exposure to the plasma jet being tested. The endotoxins in the wastewater were reduced by up to 90.22%. The variation in plasma effectiveness is probably related to the antioxidant concentration of the different investigated wastewaters.

  13. Characterization of triacetone triperoxide by ion mobility spectrometry and mass spectrometry following atmospheric pressure chemical ionization

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, Robert G.; Waltman, Melanie J.; Atkinson, David A.

    2011-04-28

    The atmospheric pressure chemical ionization of triacetone triperoxide (TATP) with subsequent separation and detection by ion mobility spectrometry has been studied. Positive ionization with hydronium reactant ions produced only fragments of the TATP molecule, with m/z 91 ion being the most predominant species. Ionization with ammonium reactant ions produced a molecular adduct at m/z 240. The reduced mobility value of this ion was constant at 1.36 cm{sup 2}V{sup -1}s{sup -1} across the temperature range from 60 to 140 C. The stability of this ion was temperature dependent and did not exist at temperatures above 140 C, where only fragment ions were observed. The introduction of ammonia vapors with TATP resulted in the formation of m/z 58 ion. As the concentration of ammonia increased, this smaller ion appeared to dominate the spectra and the TATP-ammonium adduct decreased in intensity. The ion at m/z 58 has been noted by several research groups upon using ammonia reagents in chemical ionization, but the identity was unknown. Evidence presented here supports the formation of protonated 2-propanimine. A proposed mechanism involves the addition of ammonia to the TATP-ammonium adduct followed by an elimination reaction. A similar mechanism involving the chemical ionization of acetone with excess ammonia also showed the formation of m/z 58 ion. TATP vapors from a solid sample were detected with a hand-held ion mobility spectrometer operated at room temperature. The TATP-ammonium molecular adduct was observed in the presence of ammonia and TATP vapors with this spectrometer.

  14. Characterization of triacetone triperoxide by ion mobility spectrometry and mass spectrometry following atmospheric pressure chemical ionization.

    Science.gov (United States)

    Ewing, Robert G; Waltman, Melanie J; Atkinson, David A

    2011-06-15

    The atmospheric pressure chemical ionization of triacetone triperoxide (TATP) with subsequent separation and detection by ion mobility spectrometry has been studied. Positive ionization with hydronium reactant ions produced only fragments of the TATP molecule, with m/z 91 ion being the most predominant species. Ionization with ammonium reactant ions produced a molecular adduct at m/z 240. The reduced mobility value of this ion was constant at 1.36 cm(2)V(-1)s(-1) across the temperature range from 60 to 140 °C. The stability of this ion was temperature dependent and did not exist at temperatures above 140 °C, where only fragment ions were observed. The introduction of ammonia vapors with TATP resulted in the formation of m/z 58 ion. As the concentration of ammonia increased, this smaller ion appeared to dominate the spectra and the TATP-ammonium adduct decreased in intensity. The ion at m/z 58 has been noted by several research groups upon using ammonia reagents in chemical ionization, but the identity was unknown. Evidence presented here supports the formation of protonated 2-propanimine. A proposed mechanism involves the addition of ammonia to the TATP-ammonium adduct followed by an elimination reaction. A similar mechanism involving the chemical ionization of acetone with excess ammonia also showed the formation of m/z 58 ion. TATP vapors from a solid sample were detected with a hand-held ion mobility spectrometer operated at room temperature. The TATP-ammonium molecular adduct was observed in the presence of ammonia and TATP vapors with this spectrometer.

  15. Tungsten disulfide (as catalyst) in cracking (of hydrocarbons) at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Free, G.; Meier, H.

    1943-05-19

    The catalytic effects of tungsten disulfide (code-named K5058) on paraffinic hydrocarbons at atmospheric pressure and temperatures from 400/sup 0/C to 460/sup 0/C, in a porcelain tube are considered. The principal effect was a far-reaching aromatization of the middle-oil fractions to hydrogen gas and products held tightly to the catalyst. A much less predominant effect was a cracking of the paraffins to gasoline or gaseous hydrocarbons. Variations in boilingpoint of starting material seemed to make no difference in the results. Evidence for the predominance of aromatization over cracking came from properties of reaction products (compositions, iodine numbers, aniline points, specific gravity, etc.) and thermodynamic considerations. For example, in a contrastive pari of experiments, one using K5058 and the other using K6108 (Terrana), a known cracking catalyst, but each operating on 186 grams of pure cetane (hexadecane) at temperature of 460/sup 0/ for one hour with a throughput of 1.2 vol./vol./hr, the fifferences in results were significatn. For each mole of cetane introduced, K5058 produced 0.02 moles of gasoline, 1.6 mole of hydrogen, 0.84 moles of middle oil, 0.07 moles of ethane, 0.08 moles ethylene, 0.04 moles methane, and non propane or butane, whereas K6108 produced 0.43 moles of gaoline, 0.03 moles of hydrogen, 0.69 moles of middle oil, 0.02 moles of ethane, 0.01 moles ethylene, 0.04 moles methane, and 0.34 moles of propane and butane combined. In addition, K5058 gave a considerable amount (about 7% by weight) of coke-like precipitates which were not analyzed, but which were assumed to by polymerization or condensation products from olefins or aromatics; K6108 gave almost none of this material. 5 tables

  16. How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

    Science.gov (United States)

    Leins, Martina; Gaiser, Sandra; Schulz, Andreas; Walker, Matthias; Schumacher, Uwe; Hirth, Thomas

    2015-01-01

    This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators — a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes. PMID:25938699

  17. Synthesis of magnetic nanoparticles by atmospheric-pressure glow discharge plasma-assisted electrolysis

    Science.gov (United States)

    Shirai, Naoki; Yoshida, Taketo; Uchida, Satoshi; Tochikubo, Fumiyoshi

    2017-07-01

    For the synthesis of magnetic nanoparticles (NPs), we used plasma-assisted electrolysis in which atmospheric-pressure DC glow discharge using a liquid electrode is combined with electrolysis. The solution surface is exposed to positive ions or electrons in plasma. To synthesize magnetic NPs, aqueous solutions of FeCl2 or an iron electrode immersed in liquid was used to supply iron ions in the liquid. Magnetic NPs were synthesized at the plasma-liquid interface upon the electron irradiation of the liquid surface. In the case of using aqueous solutions of FeCl2, the condition of magnetic NP synthesis depended on the gas species of plasma and the chemical agent in the liquid for controlling oxidization. The amount of magnetic NPs synthesized using plasma is not very large. On the other hand, in the case of using an iron electrode immersed in NaCl solution, magnetic NPs were synthesized without using FeCl2 solutions. When plasma-assisted electrolysis was operated, the iron electrode eluted Fe cations, resulting in the formation of magnetic NPs at the plasma-liquid interface. Magnetic NP synthesis depended on the concentration of NaCl solution and discharge current. The magnetic NPs were identified to be magnetite. By using this method, more magnetite NPs were synthesized than in the case of plasma-assisted electrolysis with FeCl2 aqueous solutions. The pH of the liquid used in plasma-assisted electrolysis was important for the synthesis of magnetite NPs.

  18. Plasma-on-chip device for stable irradiation of cells cultured in media with a low-temperature atmospheric pressure plasma.

    Science.gov (United States)

    Okada, Tomohiro; Chang, Chun-Yao; Kobayashi, Mime; Shimizu, Tetsuji; Sasaki, Minoru; Kumagai, Shinya

    2016-09-01

    We have developed a micro electromechanical systems (MEMS) device which enables plasma treatment for cells cultured in media. The device, referred to as the plasma-on-chip, comprises microwells and microplasma sources fabricated together in a single chip. The microwells have through-holes between the microwells and microplasma sources. Each microplasma source is located on the backside of each microwells. The reactive components generated by the microplasma sources pass through the through-holes and reach cells cultured in the microwells. In this study, a plasma-on-chip device was modified for a stable plasma treatment. The use of a dielectric barrier discharge (DBD) technique allowed a stable plasma treatment up to 3 min. The plasma-on-chip with the original electrode configuration typically had the maximum stable operation time of around 1 min. Spectral analysis of the plasma identified reactive species such as O and OH radicals that can affect the activity of cells. Plasma treatment was successfully performed on yeast (Saccharomyces cerevisiae) and green algae (Chlorella) cells. While no apparent change was observed with yeast, the treatment degraded the activity of the Chlorella cells and decreased their fluorescence. The device has the potential to help understand interactions between plasma and cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Synthesis and in vacuo deposition of iron oxide nanoparticles by microplasma-assisted decomposition of ferrocene

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Michael, E-mail: mvschaefer@mail.usf.edu, E-mail: axk650@case.edu, E-mail: mohan@case.edu, E-mail: schlaf@mail.usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Kumar, Ajay, E-mail: mvschaefer@mail.usf.edu, E-mail: axk650@case.edu, E-mail: mohan@case.edu, E-mail: schlaf@mail.usf.edu; Mohan Sankaran, R., E-mail: mvschaefer@mail.usf.edu, E-mail: axk650@case.edu, E-mail: mohan@case.edu, E-mail: schlaf@mail.usf.edu [Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Ohio 44106 (United States); Schlaf, Rudy, E-mail: mvschaefer@mail.usf.edu, E-mail: axk650@case.edu, E-mail: mohan@case.edu, E-mail: schlaf@mail.usf.edu [Department of Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States)

    2014-10-07

    Microplasma-assisted gas-phase nucleation has emerged as an important new approach to produce high-purity, nanometer-sized, and narrowly dispersed particles. This study aims to integrate this technique with vacuum conditions to enable synthesis and deposition in an ultrahigh vacuum compatible environment. The ultimate goal is to combine nanoparticle synthesis with photoemission spectroscopy-based electronic structure analysis. Such measurements require in vacuo deposition to prevent surface contamination from sample transfer, which can be deleterious for nanoscale materials. A homebuilt microplasma reactor was integrated into an existing atomic layer deposition system attached to a surface science multi-chamber system equipped with photoemission spectroscopy. As proof-of-concept, we studied the decomposition of ferrocene vapor in the microplasma to synthesize iron oxide nanoparticles. The injection parameters were optimized to achieve complete precursor decomposition under vacuum conditions, and nanoparticles were successfully deposited. The stoichiometry of the deposited samples was characterized in situ using X-ray photoelectron spectroscopy indicating that iron oxide was formed. Additional transmission electron spectroscopy characterization allowed the determination of the size, shape, and crystal lattice of the particles, confirming their structural properties.

  20. The utility of continuum simulations for direct current and microwave microplasmas

    Science.gov (United States)

    Ayyaswamy, Venkattraman; Alamatsaz, Arghavan; Verma, Abhishek Kumer

    2017-10-01

    State-of-the-art microplasma devices have contributed to several challenges that require a fundamental understanding of the various mechanisms involved in order to achieve optimal operation for a given application. In this context, the role of computations cannot be stressed enough. Historically, the computational techniques used for simulating plasmas belong to two categories `` continuum/fluid and kinetic methods. The primary goal of the current work is to perform an exhaustive comparison of continuum and kinetic simulations for a range of operating conditions. Kinetic simulations using the particle-in-cell with Monte Carlo collisions (PIC-MCC) method and continuum simulations using the full-momentum equation are performed at various operating conditions. It is shown that using the electron energy distribution function (EEDF) predicted by BOLSIG+ in continuum simulations of direct current microplasmas leads to a significant under-prediction of plasma densities. The discrepancy between kinetic and continuum simulations is attributed to the presence of hot electrons created as a result of secondary emission. On the other hand, continuum simulations performed for a microwave microplasma operating at 0.5 GHz showed excellent agreement with kinetic simulations.

  1. Time-resolved microplasma electron dynamics in a pulsed microwave discharge

    Science.gov (United States)

    Monfared, S. K.; Hoskinson, A. R.; Hopwood, J.

    2013-10-01

    Microwave-driven microplasmas are typically operated in a steady-state mode in which the electron temperature is constant in time. Transient measurements of excitation temperature and helium emission lines, however, suggest that short microwave pulses can be used to increase the electron energy by 20-30%. Time-resolved optical emission spectrometry reveals an initial burst of light emission from the igniting microplasma. This emission overshoot is also correlated with a measured increase in excitation temperature. Excimer emission lags atomic emission, however, and does not overshoot. A simple model shows that an increase in electron temperature is responsible for the overshoot of atomic optical emission at the beginning of each microwave pulse. The formation of dimers and subsequent excimer emission requires slower three-body collisions with the excited rare gas atoms, which is why excimer emission does not overshoot the steady-state values. Similar results are observed in argon gas. The overshoot in electron temperature may be used to manipulate the collisional production of species in microplasmas using short, low-duty cycle microwave pulses.

  2. Time-resolved microplasma excitation temperature in a pulsed microwave discharge

    Science.gov (United States)

    Hopwood, Jeffrey; Monfared, Shabnam; Hoskinson, Alan

    2013-09-01

    Microwave-driven microplasmas are usually operated in a steady-state mode such that the electron temperature is constant in time. Transient measurements of excitation temperature and helium emission lines, however, suggest that short microwave pulses can be used to raise the electron energy by 20-30% for approximately 100 ns. Time-resolved optical emission spectrometry reveals an initial burst of light emission from the igniting microplasma. This emission overshoot is also correlated with a measured increase in excitation temperature. Excimer emission lags atomic emission, however, and does not overshoot. A simple model demonstrates that an increase in electron temperature is responsible for the overshoot of atomic optical emission at the beginning of each microwave pulse. The formation of dimers and subsequent excimer emission requires slower three-body collisions with the excited rare gas atom; this is why excimer emission does not overshoot the steady state value. Similar experimental and modeling results are observed in argon gas. The overshoot in electron temperature may be used to manipulate the collisional production of species in microplasmas using short, low-duty cycle microwave pulses. This material is based upon work supported by the USAF and Physical Sciences Inc., under contract No. FA8650-C-12-C-2312. Additional support was provided by the DARPA MPD program under award FA9550-12-1-0006.

  3. H2O and CO2 vapor pressure measurements at temperatures relevant to the middle atmosphere of Earth and Mars

    Science.gov (United States)

    Nachbar, M.; Duft, D.; Leisner, T.

    2017-09-01

    Measurements of the vapor pressure of H2O and CO2 at temperatures relevant to the middle atmosphere of Earth and Mars are rare but important in order to describe cloud formation and ice particle growth processes. In this contribution we present a novel technique for measuring the vapor pressure of condensable gases by analyzing the depositional growth rates on free nanoparticles at high supersaturation. The method is applied to measure the vapor pressure of CO2 between 75K and 85K. By comparison with previous measurements and parameterizations we are able to show the excellent functionality of the method. In addition, the method is used to measure the vapor pressure over H2O ice between 135K and 160K. We show that the vapor pressure of so called stacking disordered ice Isd deposited at temperatures below 160K is significantly higher compared to hexagonal ice Ih. The consequences for ice cloud formation in the atmosphere of Earth and Mars will be discussed.

  4. Tailoring electron energy distribution functions through energy confinement in dual radio-frequency driven atmospheric pressure plasmas

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, C.; Waskoenig, J. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Gans, T. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2012-10-08

    A multi-scale numerical model based on hydrodynamic equations with semi-kinetic treatment of electrons is used to investigate the influence of dual frequency excitation on the effective electron energy distribution function (EEDF) in a radio-frequency driven atmospheric pressure plasma. It is found that variations of power density, voltage ratio, and phase relationship provide separate control over the electron density and the mean electron energy. This is exploited to directly influence both the phase dependent and time averaged effective EEDF. This enables tailoring the EEDF for enhanced control of non-equilibrium plasma chemical kinetics at ambient pressure and temperature.

  5. Temperature and atmospheric pressure may be considered as predictors for the occurrence of bacillary dysentery in Guangzhou, Southern China

    Directory of Open Access Journals (Sweden)

    Tiegang Li

    2014-06-01

    Full Text Available Introduction The control of bacillary dysentery (BD remains a big challenge for China. Methods Negative binomial multivariable regression was used to study relationships between meteorological variables and the occurrence of BD during the period of 2006-2012. Results Each 1°C rise of temperature corresponded to an increase of 3.60% (95%CI, 3.03% to 4.18% in the monthly number of BD cases, whereas a 1 hPa rise in atmospheric pressure corresponded to a decrease in the number of BD cases by 2.85% (95%CI = 3.34% to 2.37% decrease. Conclusions Temperature and atmospheric pressure may be considered as predictors for the occurrence of BD in Guangzhou.

  6. Optical properties of the atmospheric pressure helium plasma jet generated by alternative current (a.c.) power supply

    Energy Technology Data Exchange (ETDEWEB)

    Ilik, Erkan, E-mail: eilik@ogu.edu.tr; Akan, Tamer [Faculty of Arts and Sciences, Department of Physics, Eskisehir Osmangazi University, 26480 Eskisehir (Turkey)

    2016-05-15

    In this work, an atmospheric pressure plasma jet (APPJ) was produced to generate cold flowing post-discharge plasma of pure helium gas. The main aim of this study was to generate cold flowing APPJ of pure helium gas and to determine how their optical emission spectrum change influences varying different flow rates. Lengths of early, middle, and late post-discharge plasma (jet) regions and their fluctuations were determined, respectively. Then, ignition condition dependence of the post-discharge plasma for flow rate was specified at a constant voltage. Spectroscopic studies of an atmospheric pressure plasma jet of helium were presented via analyzing OH, N{sub 2}, N{sub 2}{sup +}, oxygen, and helium intensities for various flow rates.

  7. Orientation Control of ZnO Films Deposited Using Nonequilibrium Atmospheric Pressure N2/O2 Plasma

    Science.gov (United States)

    Nose, Yukinori; Nakamura, Tatsuru; Yoshimura, Takeshi; Ashida, Atsushi; Uehara, Tsuyoshi; Fujimura, Norifumi

    2013-01-01

    Nonequilibrium atmospheric pressure N2/O2 plasma was applied to the chemical vapor deposition (CVD) of zinc oxide (ZnO) films on glass substrates at the substrate temperature of 200 °C. Although the deposition temperature is very low, the ZnO films showed (0001) preferred orientation including a small amount of diffraction from the (1011) plane. We attempted to improve the (0001) preferred orientation for ZnO films without increasing the substrate temperature. After systematic experiments, we found that adjusting the ratio of the oxygen flow rate in the total gas flow rate [O2/(O2+ N2) ratio] was effective for orientation control of the ZnO films. This result indicates the potential of nonequilibrium atmospheric pressure N2/O2 plasma for the low-temperature CVD process of ZnO films used in piezoelectric devices and transparent thin-film transistors on a flexible substrate.

  8. Gas adsorption and desorption effects on high pressure small volume cylinders and their relevance to atmospheric trace gas analysis

    Science.gov (United States)

    Satar, Ece; Nyfeler, Peter; Pascale, Céline; Niederhauser, Bernhard; Leuenberger, Markus

    2017-04-01

    Long term atmospheric monitoring of trace gases requires great attention to precision and accuracy of the measurement setups. For globally integrated and well established greenhouse gas observation networks, the World Meteorological Organization (WMO) has set recommended compatibility goals within the framework of its Global Atmosphere Watch (GAW) Programme [1]. To achieve these challenging limits, the measurement systems are regularly calibrated with standard gases of known composition. Therefore, the stability of the primary and secondary gas standards over time is an essential issue. Past studies have explained the small instabilities in high pressure standard gas cylinders through leakage, diffusion, regulator effects, gravimetric fractionation and surface processes [2, 3]. The latter include adsorption/desorption, which are functions of temperature, pressure and surface properties. For high pressure standard gas mixtures used in atmospheric trace gas analysis, there exists only a limited amount of data and few attempts to quantify the surface processes [4, 5]. Specifically, we have designed a high pressure measurement chamber to investigate trace gases and their affinity for adsorption on different surfaces over various temperature and pressure ranges. Here, we focus on measurements of CO2, CH4 and CO using a cavity ring down spectroscopy analyzer and quantify the concentration changes due to adsorption/desorption. In this study, the first results from these prototype cylinders of steel and aluminum will be presented. References [1] World Meteorological Organization (WMO), Global Atmosphere Watch.(GAW): Report No. 229, 18th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques (GGMT-2015), 2016. [2] Keeling, R. F., Manning, A. C., Paplawsky, W. J., and Cox, A. C.: On the long-term stability of reference gases for atmospheric O2 /N2 and CO2 measurements, Tellus B, 59, 10.3402/tellusb.v59i1.16964, 2007. [3

  9. Effects and Mechanism of Atmospheric-Pressure Dielectric Barrier Discharge Cold Plasma on Lactate Dehydrogenase (LDH) Enzyme

    OpenAIRE

    Hao Zhang; Zimu Xu; Jie Shen; Xu Li; Lili Ding; Jie Ma; Yan Lan; Weidong Xia; Cheng Cheng; Qiang Sun; Zelong Zhang; Chu, Paul K

    2015-01-01

    Proteins are carriers of biological functions and the effects of atmospheric-pressure non-thermal plasmas on proteins are important to applications such as sterilization and plasma-induced apoptosis of cancer cells. Herein, we report our detailed investigation of the effects of helium-oxygen non-thermal dielectric barrier discharge (DBD) plasmas on the inactivation of lactate dehydrogenase (LDH) enzyme solutions. Circular dichroism (CD) and dynamic light scattering (DLS) indicate that the los...

  10. Experimental and numerical study of the propagation of a discharge in a capillary tube in air at atmospheric pressure

    OpenAIRE

    Jánský, Jaroslav; Le Delliou, Pierre; Tholin, Fabien; Tardiveau, Pierre; Bourdon, Anne; Pasquiers, Stéphane

    2011-01-01

    Abstract This paper presents an experimental and numerical study of a pulsed air plasma discharge at atmospheric pressure propagating in a capillary glass tube. In this work, we have compared the discharge structures and the axial propagation velocities of discharges. First, we have studied a needle-to-plane configuration without tube. For applied voltages in the range 7 ? 18 kV, we have observed in experiments and in simulations that a plasma ball starts to develop around the needle tip. ...

  11. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    OpenAIRE

    Pai, David,; Lacoste, Deanna,; Laux, C.

    2010-01-01

    International audience; In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determine...

  12. Analysis of frequency response and scale-factor of tuning fork micro-gyroscope operating at atmospheric pressure.

    Science.gov (United States)

    Ding, Xukai; Li, Hongsheng; Ni, Yunfang; Sang, Pengcheng

    2015-01-22

    This paper presents a study of the frequency response and the scale-factor of a tuning fork micro-gyroscope operating at atmospheric pressure in the presence of an interference sense mode by utilizing the approximate transfer function. The optimal demodulation phase (ODP), which is always ignored in vacuum packaged micro-gyroscopes but quite important in gyroscopes operating at atmospheric pressure, is obtained through the transfer function of the sense mode, including the primary mode and the interference mode. The approximate transfer function of the micro-gyroscope is deduced in consideration of the interference mode and the ODP. Then, the equation describing the scale-factor of the gyroscope is also obtained. The impacts of the interference mode and Q-factor on the frequency response and the scale-factor of the gyroscope are analyzed through numerical simulations. The relationship between the scale-factor and the demodulation phase is also illustrated and gives an effective way to find out the ODP in practice. The simulation results predicted by the transfer functions are in close agreement with the results of the experiments. The analyses and simulations can provide constructive guidance on bandwidth and sensitivity designs of the micro-gyroscopes operating at atmospheric pressure.

  13. Characteristics of a micro-gap argon barrier discharge excited by a saw-tooth voltage at atmospheric pressure

    Science.gov (United States)

    Li, Xuechen; Zhang, Qi; Jia, Pengying; Chu, Jingdi; Zhang, Panpan; Dong, Lifang

    2017-03-01

    Using two water electrodes, a micro-gap dielectric barrier discharge excited by a saw-tooth voltage is investigated in atmospheric pressure argon. Through electrical and optical measurements, it is found that, at a lower driving frequency, a stepped discharge mode is obtained per half voltage cycle. Moreover, the duration and amplitude of the current plateau increase with the increase in the applied peak voltage. With the increase in the driving frequency, the stepped discharge mode transits into a pulsed one after a multi-peak mode. During this process, a diffuse discharge at a lower frequency transits into a filamentary one at a higher frequency. Temporal evolutions of the discharges are investigated axially based on fast photography. It is found that the stepped mode is in atmospheric pressure Townsend discharge (APTD) regime. However, there is a transition from APTD to atmospheric pressure glow discharge for the pulsed mode. Spectral intensity ratio of 391.4 nm to 337.1 nm is used to determine the averaged electron energy, which decreases with increasing peak voltage or driving frequency.

  14. Clinical use of cold atmospheric pressure argon plasma in chronic leg ulcers: A pilot study.

    Science.gov (United States)

    Ulrich, C; Kluschke, F; Patzelt, A; Vandersee, S; Czaika, V A; Richter, H; Bob, A; Hutten, J von; Painsi, C; Hüge, R; Kramer, A; Assadian, O; Lademann, J; Lange-Asschenfeldt, B

    2015-05-01

    In the age of multiresistant microbes and the increasing lack of efficient antibiotics, conventional antiseptics play a critical role in the prevention and therapy of wound infections. Recent studies have demonstrated the antiseptic effects of cold atmospheric pressure plasma (APP). In this pilot, study we investigate the overall suitability of one of the first APP sources for wound treatment focusing on its potential antimicrobial effects. The wound closure rate and the bacterial colonisation of the wounds were investigated. Patients suffering from chronic leg ulcers were treated in a clinical controlled monocentric trial with either APP or octenidine (OCT). In patients who presented with more than one ulceration in different locations, one was treated with APP and the other one with OCT. Each group was treated three times a week over a period of two weeks. The antimicrobial efficacy was evaluated immediately after and following two weeks of treatment. Wounds treated with OCT showed a significantly higher microbial reduction (64%) compared to wounds treated with APP (47%) immediately after the treatment. Over two weeks of antiseptic treatment the bacterial density was reduced within the OCT group (-35%) compared to a slight increase in bacterial density in the APP-treated group (+12%). Clinically, there were no signs of delayed wound healing observed in either group and both treatments were well tolerated. The immediate antimicrobial effects of the APP prototype source were almost comparable to OCT without any signs of cytotoxicity. This pilot study is limited by current configurations of the plasma source, where the narrow plasma beam made it difficult to cover larger wound surface areas and in order to avoid untreated areas of the wound bed, smaller wounds were assigned to the APP-treatment group. This limits the significance of AAP-related effects on the wound healing dynamics, as smaller wounds tend to heal faster than larger wounds. However, clinical wound

  15. Resonance broadening of argon lines in a micro-scaled atmospheric pressure plasma jet (argon μAPPJ)

    Science.gov (United States)

    Pipa, A. V.; Ionikh, Yu. Z.; Chekishev, V. M.; Dünnbier, M.; Reuter, S.

    2015-06-01

    Optical emission from atmospheric pressure micro-jet operating with pure argon (argon μAPPJ) flow has been detected with a moderate resolution spectrometer. Large broadening of the several argon (Ar) lines has been observed in the near infrared spectral region. This effect was attributed to resonance broadening of the s2 (Paschen notation) level in 3p54s configuration. In the present work, corresponding line profiles are suggested for plasma diagnostics. For this, a general case of resonance broadening coefficient of noble gases is discussed. As broadening reflects the Ar density, and the static gas pressure of the jet is in equilibrium with the ambient, the local gas temperature can be inferred. An estimation of gas temperature from the width of the 750 nm Ar line is in agreement with rotational temperature of OH radicals determined from the A2Σ+ → X2Π (0, 0) band. At low temperatures (300-600 K) and at partial Ar pressure near atmospheric, the resonance width of the suggested lines is very sensitive to small temperature variations. High temperature sensitivity and large width make the resonance broadened lines very attractive for diagnostics of low temperature discharges at elevated pressure, e.g., as they are used in plasma-medicine.

  16. Experimental Study of Coaxial Cylinder Dielectric Barrier Discharge in Ar/NH3 Mixtures under the Atmosphere-Pressure.

    Science.gov (United States)

    Li, Yan-qin; Bu, De-cai; Di, Lan-bo; Zhang, Xiu-ling; Liu, Zhi-sheng; Li, Xue-hui

    2015-03-01

    An atmosphere-pressure Dielectric Barrier Discharge in Ar/NH3 mixtures between cylinder electrodes is studied by Optical Emission Spectroscopy and the main particles of atmosphere-pressure Ar/NH3 DBD plasma are NH, N, N+, N2, Ar, H(α) and OH. NH is decomposition products of NH3, and NH(c 1π) and NH(A 3π) are two kinds of excited-state neutral particles and produced by penning ionization of Ar* and NH3. The nitrogen active atom is detected at 674.5 nm which may provide the experimental foundation for the synthesis of ε-Fe3N ferroparticles by the atmosphere-pressure Ar/NH3 DBD plasma. The intensities of main particles are analyzed at different NH3 flow rate and applied voltage peak-peak value. The results show that the spectral line intensities of various particles increase with the rise of the applied voltage peak-peak value at the same NH3 flow rate, and first increase and then decrease with the increase of the NH3 flow rate at the same applied voltage peak-peak value. The applied voltage peak-peak value being kept constant, the spectral line intensity of nitrogen active atom first increases and then decreases with the increase of the NH3 flow rate. When NH3 flow rate is 20 mL x min(-1), the spectral line intensity of nitrogen active atom reaches a maximum at the same applied voltage peak-peak value. The spectral line intensity of nitrogen active atom decreases gradually with increasing the applied voltage peak-peak value at the same NH3 flow rate and it is mainly because of the translation of discharge mode from multi-pulse APGD to filamentary discharge in the atmosphere-pressure Ar/NH3 DBD. The microdischarge channels overlap and the microdischarges affect each other in multi-pulse APGD; hence the increasing rate of the spectral line intensity is quicker in multi-pulse APGD than in filamentary discharge with increasing the applied voltage peak-peak value. When the applied voltage peak-peak value is up from 4 600 to 6 400 V, the single-pulse and two-pulse APGD

  17. Signal processing of diurnal and semidiurnal variations in radon and atmospheric pressure: A new tool for accurate in situ measurement of soil gas velocity, pressure gradient, and tortuosity

    Science.gov (United States)

    Pinault, Jean-Louis; Baubron, Jean-Claude

    1997-08-01

    Signal processing of diurnal and semidiurnal variations of both atmospheric pressure and radon concentration in soil gases is shown to be useful for estimating soil gas transport parameters. The two daily-cycle peaks at 12- and 24-hour periods in the Power Spectral Density (PSD) of atmospheric pressure seem to be present everywhere on Earth's surface, and it is the effect of these regular pressure variations on the radon concentration in soil gases that makes it possible to determine three soil gas transport parameters which can be used to estimate real gas velocity; i.e. tortuosity τ, the ratio k/n between intrinsic permeability and effective porosity (that part of porosity involved in gas transport), and the pressure gradient α. The parameters k and n can be determined independently if the gas flux at the surface is measured at the same time. The method is robust, representative, and accurate: since it allows reliable estimation of transport parameters, it can provide relevant information about the depth of the radon source and the time it takes for information to reach the surface when radon bursts occur at depth. Radon is an appropriate soil gas tracer because it exists in all soils. Moreover, the measurement of radon concentration requires only passive sensors that do not hamper the rising gas column. Gas flux data obtained in Andalusia, Spain, in connection with mineral exploration are processed as examples. Determining the complete set of transport parameters helps in the interpretation of recorded radon outbursts, which are found to be correlated with regional seismic activity.

  18. Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

    Science.gov (United States)

    Yambe, Kiyoyuki; Saito, Hidetoshi

    2017-12-01

    When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

  19. Comparison of electrospray ionisation, atmospheric pressure chemical ionisation and atmospheric pressure photoionisation for the identification of metabolites from labile artemisinin-based anti-malarial drugs using a QTRAP® mass spectrometer.

    Science.gov (United States)

    Louw, Stefan; Njoroge, Mathew; Chigorimbo-Murefu, Nyaradzo; Chibale, Kelly

    2012-10-30

    Artemisinin-based drugs and their metabolites are prone to in-source fragmentation under atmospheric pressure ionisation mass spectrometry (API-MS) conditions. To facilitate correct and efficient identification of all possible drug metabolites using full scan MS analyzer methods, stable [M + NH(4) ](+) ions should be produced in the MS source. Using a high-performance liquid chromatography (HPLC) hybrid triple quadrupole linear ion trap MS system, electrospray ionisation (ESI), atmospheric pressure chemical ionisation (APCI) and atmospheric pressure photoionisation (APPI) methods were developed for the detection of [M + NH(4) ](+) ions of the test compounds dihydroartemisinin, artemisinin, artemether and artesunic acid. The optimised methods employed ammonium formate buffered HPLC mobile phase in combination with moderate source temperatures (100-200 °C) and showed satisfactorily reduced in-source fragmentation. With a full scan MS analyser method for the detection of the in vitro metabolites of the test compounds, the respective performance of the ESI and APCI methods was found to be comparable. ESI generally resulted in less in-source fragmentation. Incorrect assignment of metabolites resulted from strong in-source fragmentation of artemether using the APPI method. The most number of metabolites could be detected using ESI in combination with a selective MS analyser method. ESI and APCI full scan methods proved to be capable of detecting any drug metabolites present in reasonable concentrations, and are useful when employed in addition to selective scan methods that target low level expected metabolites. APPI can be a valuable alternative for detecting expected metabolites due to good signal-to-noise (S/N) ratio. Copyright © 2012 John Wiley & Sons, Ltd.

  20. Generation and size classification of single-walled carbon nanotube aerosol using atmospheric pressure pulsed laser ablation (AP-PLA)

    Science.gov (United States)

    Klanwan, Jiraporn; Seto, Takafumi; Furukawa, Takuma; Otani, Yoshio; Charinpanitkul, Tawatchai; Kohno, Masamichi; Hirasawa, Makoto

    2010-10-01

    Gas suspended single-walled carbon nanotubes (SWCNTs) with single tube diameter smaller than 2 nm and length of longer than 500 nm were generated by simple and continuous system using laser ablation technique under atmospheric conditions. Graphite target containing 0.5 wt%-nickel and 0.5 wt%-cobalt was ablated by Nd:YAG laser in an electrical furnace under atmospheric pressure of nitrogen flow that allowed one step and continuous synthesis of the SWCNTs. Size distribution of the gas suspended SWCNTs aerosol was measured using size-classification by a differential mobility analyzer (DMA) coupled with a condensation particle counter (CPC) used as a detector. Characteristics of SWCNT aerosol generated under the different temperature were also investigated using scanning and transmission electron microscopes and Raman scattering. Mono-mobility SWCNT aerosol with mobility diameter of 100 and 200 nm was successfully prepared after the size separation using a DMA.