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1

Cold plasma brush generated at atmospheric pressure  

SciTech Connect

A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4 W) up to tens of watts (up to 45 W). The plasma can be ignited and sustained in both continuous and pulsed modes with different plasma gases such as argon or helium, but argon was selected as a primary gas for use in this work. The brush-shaped plasma is formed and extended outside of the discharge chamber with typical dimension of 10-15 mm in width and less than 1.0 mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42 deg. C) when running with a relatively high gas flow rate of about 3500 ml/min. For an argon plasma brush, the operating voltage from less than 500 V to about 2500 V was tested, with an argon gas flow rate varied from less than 1000 to 3500 ml/min. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical applications including battery-powered operation and use in large-scale applications. Several polymer film samples were tested for surface treatment with the newly developed device, and successful changes of the wettability property from hydrophobic to hydrophilic were achieved within a few seconds.

Duan Yixiang; Huang, C.; Yu, Q. S. [C-CSE, MS K484, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Chemical Engineering, Center for Surface Science and Plasma Technology, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

2007-01-15

2

Cold plasma brush generated at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4 W) up to tens of watts (up to 45 W). The plasma can be ignited and sustained in both continuous and pulsed modes with different plasma gases such as argon or helium, but argon was selected as a primary gas for use in this work. The brush-shaped plasma is formed and extended outside of the discharge chamber with typical dimension of 10-15 mm in width and less than 1.0 mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42 °C) when running with a relatively high gas flow rate of about 3500 ml/min. For an argon plasma brush, the operating voltage from less than 500 V to about 2500 V was tested, with an argon gas flow rate varied from less than 1000 to 3500 ml/min. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical applications including battery-powered operation and use in large-scale applications. Several polymer film samples were tested for surface treatment with the newly developed device, and successful changes of the wettability property from hydrophobic to hydrophilic were achieved within a few seconds.

Duan, Yixiang; Huang, C.; Yu, Q. S.

2007-01-01

3

Cold atmospheric pressure air plasma jet for medical applications  

SciTech Connect

By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2 cm long plasma jet. With increasing flow rate, the flow becomes turbulent and temperatures of the jet are reduced to values close to room temperature. Utilizing the jet, yeast grown on agar can be eradicated with a treatment of only a few seconds. Conversely, animal studies show no skin damage even with exposures ten times longer than needed for pathogen extermination. This cold plasma jet provides an effective mode of treatment for yeast infections of the skin.

Kolb, J. F.; Price, R. O.; Bowman, A.; Chiavarini, R. L.; Stacey, M.; Schoenbach, K. H. [Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23510 (United States); Mohamed, A.-A H. [Department of Physics, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt); Swanson, R. J. [Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23510 (United States); Department of Biological Sciences, Old Dominion University, Norfolk, Virginia 23529 (United States)

2008-06-16

4

Cold atmospheric pressure plasma jet interactions with plasmid DNA  

SciTech Connect

The effect of a cold (<40 deg. C) radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. Gel electrophoresis was used to analyze the DNA forms post-treatment. The experimental data are fitted to a rate equation model that allows for quantitative determination of the rates of single and double strand break formation. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks.

O'Connell, D.; Cox, L. J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Graham, W. G.; Gans, T.; Currell, F. J. [Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, Northern Ireland (United Kingdom)

2011-01-24

5

Atmospheric pressure cold plasma as an antifungal therapy  

SciTech Connect

A microhollow cathode based, direct-current, atmospheric pressure, He/O{sub 2} (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

Sun Peng; Wu Haiyan [College of Engineering, Peking University, Beijing 100871 (China); Sun Yi; Liu Wei; Li Ruoyu [Department of Dermatology and Venereology, Peking Univ. 1st Hospital and Research Center for Medical Mycology, Peking Univ., Beijing 100034 (China); Zhu Weidong; Lopez, Jose L. [Department of Applied Science and Technology and Center for Microplasma Science and Technology, Saint Peter's College, Jersey City, New Jersey 07306 (United States); Zhang Jue; Fang Jing [College of Engineering, Peking University, Beijing 100871 (China); Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China)

2011-01-10

6

Air Purification Pavement Surface Coating by Atmospheric Pressure Cold Plasma  

NASA Astrophysics Data System (ADS)

This study develops an atmospheric pressure cold plasma (APCP) reactor to produce activated radicals from precursor molecules, and to immobilize nano titanium dioxide (TiO2) powder to substrate pavement materials. TiO2 has photocatalytic properties and under UV light can be used to oxidize and remove volatile organic compounds (VOCs) and nitrogen oxides (NOx) from the atmosphere. Although TiO2 treated paving materials have great potential to improve air quality, current techniques to adhere TiO2 to substrate materials are either not durable or reduce direct contact of TiO2 with UV light, reducing the photocatalytic effect. To solve this technical difficulty, this study introduces APCP techniques to transportation engineering to coat TiO2 to pavement. Preliminary results are promising and show that TiO2 can be incorporated successfully into an APCP environment and can be immobilized at the surface of the asphalt substrate. The TiO2 coated material with APCP shows the ability to reduce nitrogen oxides when exposed to UV light in an environmental chamber. The plasma reactor utilizes high voltage streamers as the plasma source.

Westergreen, Joe; Pedrow, Patrick; Shen, Shihui; Jobson, Bertram

2011-11-01

7

Atmospheric pressure resistive barrier cold plasma for biological decontamination  

Microsoft Academic Search

Steady-state atmospheric pressure nonthermal plasmas can splendidly debilitate bacteria in liquids, gases, and on surfaces, as well as can disintegrate hazardous chemicals. The nonthermal resistive barrier gas discharge at atmospheric pressure is currently investigated for low-temperature sterilization purposes. We have carried out electrical, chemical, optical, and biological studies of the discharge, with the intent of identifying the chemically and biologically

Magesh Thiyagarajan; Igor Alexeff; Sriram Parameswaran; Stephen Beebe

2005-01-01

8

Atmospheric Pressure Resistive Barrier Cold Plasma for Biological Decontamination  

Microsoft Academic Search

Summary form only given. We have investigated the non thermal resistive barrier gas discharge at atmospheric pressure for low temperature sterilization purposes. We have carried out electrical, chemical, optical, and biological studies on the discharge, with the intent of identifying the chemically and biologically active species produced. We have also demonstrated that effective decontamination can be achieved without causing any

I. Alexeff; S. Beebe; S. Parameswaran; M. Thiyagarajan; E. P. Michael; J. Dhanraj

2005-01-01

9

Cold Micro-Plasma Jets in Atmospheric Pressure Air  

NASA Astrophysics Data System (ADS)

Direct current microhollow cathode discharges (MHCDs) have been operated in air, nitrogen and oxygen at pressures of one atmosphere. The electrodes are 250 ?m thick molybdenum foils, separated by an alumina insulator of the same thickness. A cylindrical hole with a diameter in the 100 ?m range is drilled through all layers. By flowing gases at high pressure through this hole, plasma jets with radial dimensions on the same order as the microhole dimensions, and with lengths of up to one centimeter are generated. The gas temperature in these jets was measured by means of a micro-thermocouple. The lowest temperatures of close to room temperature were measured when the flow changed from laminar to turbulent. The results of spectral emission and absorption studies indicate high concentrations of byproducts, such as ozone, when the discharge is operated in air or oxygen. This work is supported by the U.S Air Force Office of Scientific Research (AFOSR).

Mohamed, A. H.; Suddala, S.; Schoenbach, K. H.

2003-10-01

10

Io's atmosphere - Pressure control by regolith cold trapping and surface venting  

NASA Astrophysics Data System (ADS)

A new model for the basal pressure of Io's atmosphere is developed. This model takes into account the previously ignored fact that much of Io's surface has very high porosity, typically about 90 pct. Such porosity allows efficient subsurface cold trapping of atmospheric gases which tends to keep ambient surface pressures very low. SO2 is the only gas identified on Io, and the basal pressures for atmospheric models are usually pegged to local surface temperature via the SO2 vapor pressure equilibrium curve. Near Io's subsolar point the pressure in equilibrium with a surface SO2 frost deposit is about 1/10,000,000th bar. Porous surface models of the type developed invoke equilibrium with the colder, subsurface permafrost (at about 3-cm depth) and yield pressures of about 1/10 to the 12th bar. The subsurface cold trapping model explains many but not all observations relevant to Io's atmosphere. The new subsurface cold trapping model and the earlier surface frost equilibrium model, when taken together, provide lower and upper limits, respectively, on the basal SO2 pressure of Io's atmosphere.

Matson, D. L.; Nash, D. B.

1983-06-01

11

Fabrication of transparent antifouling thin films with fractal structure by atmospheric pressure cold plasma deposition.  

PubMed

Antifouling surface with both superhydrophobicity and oil-repellency has been fabricated on glass substrate by forming fractal microstructure(s). The fractal microstructure was constituted by transparent silica particles of 100 nm diameter and transparent zinc-oxide columns grown on silica particles by atmospheric pressure cold plasma deposition. The sample surface was coated with a chemically adsorbed monomolecular layer. We found that one sample has the superhydrophobic ability with a water droplet contact angle of more than 150°, while another sample has a high transmittance of more than 85% in a wavelength range from 400 to 800 nm. PMID:23186100

Miyagawa, Hayato; Yamauchi, Koji; Kim, Yoon-Kee; Ogawa, Kazufumi; Yamaguchi, Kenzo; Suzaki, Yoshifumi

2012-12-21

12

Modelling of OH production in cold atmospheric-pressure He-H2O plasma jets  

NASA Astrophysics Data System (ADS)

Results of the modelling of OH production in the plasma bullet mode of cold atmospheric-pressure He-H2O plasma jets are presented. It is shown that the dominant source of OH molecules is related to the Penning and charge transfer reactions of H2O molecules with excited and charged helium species produced by guided streamers (plasma bullets), in contrast to the case of He-H2O glow discharges where OH production is mainly due to the dissociation of H2O molecules by electron impact.

Naidis, G. V.

2013-06-01

13

Parametric study of a cold plasma jet generated at atmospheric pressure  

NASA Astrophysics Data System (ADS)

The distinct discharge characteristics of an atmospheric-pressure cold plasma jet are investigated by using the temporal evolution of optical images and the discharge/substrate current. In a tube-type helium plasma jet reactor composed of a central high-voltage capillary electrode in a quartz tube and a ring-shaped ground electrode, plasma jet exhibits three discharge types, and the particular discharge type determines the variations in the discharge/substrate current and the relevant spatial characteristics of a jet. In order to find operation criteria to minimize substrate current induced material damage, we suggest diagrams of the discharge type and maximum substrate current in terms of the control parameters.

Kang, Woo Seok; Hur, Min; Song, Young-Hoon

2013-02-01

14

Cold-atmospheric pressure plasma polymerization of acetylene on wood flour for improved wood plastics composites  

NASA Astrophysics Data System (ADS)

Plastic composites have become a large class of construction material for exterior applications. One of the main disadvantages of wood plastic composites resides in the weak adhesion between the polar and hydrophilic surface of wood and the non-polar and hydrophobic polyolefin matrix, hindering the dispersion of the flour in the polymer matrix. To improve interfacial compatibility wood flour can be pretreated with environmentally friendly methods such as cold-atmospheric pressure plasma. The objective of this work is therefore to evaluate the potential of plasma polymerization of acetylene on wood flour to improve the compatibility with polyolefins. This presentation will describe the reactor design used to modify wood flour using acetylene plasma polymerization. The optimum conditions for plasma polymerization on wood particles will also be presented. Finally preliminary results on the wood flour surface properties and use in wood plastic composites will be discussed.

Lekobou, William; Pedrow, Patrick; Englund, Karl; Laborie, Marie-Pierre

2009-10-01

15

Temporal and spatial resolved optical emission behaviors of a cold atmospheric pressure plasma jet  

SciTech Connect

The propagation behavior of cold atmospheric pressure plasma jets has recently attracted lots of attention. In this paper, a cold He plasma jet generated by a single plasma electrode jet device is studied. The spatial-temporal resolved optical emission spectroscopy measurements are presented. It is found that the emission intensity of the He 706.5 nm line of the plasma behaves similarly both inside the syringe and in the surrounding air (plasma plume). It decreases monotonously, which is different from the emission lines, such as N{sub 2} 337.1 nm line, N{sub 2}{sup +} 391.4 nm line, and O 777.3 nm line. For the discharge inside the syringe, the emission intensity of the He 706.5 nm line decays more rapidly than that of the other three spectral lines mentioned above. The N{sub 2} 337.1 nm line behaves a similar time evolution with the discharge current. For the N{sub 2}{sup +} 391.4 nm line and the atomic O 777.3 nm line, both of them decay slower than that of the He 706.5 nm and the N{sub 2} 337.1 nm. When the plasma plume propagates further away from the nozzle, the temporal behaviors of the emission intensities of the four lines tend to be similar gradually. Besides, it is found that, when the size of the plasma bullet appears biggest, the propagation velocity of the bullet achieves its highest value while the emission intensity of the N{sub 2}{sup +} 391.4 nm line reaches its maximum. Detailed analysis shows that the Penning effect between the metastable state He{sub m} and the air molecules may play a significant role in the propagation of the plasma bullet in the open air.

Xiong, Q.; Lu, X.; Liu, J.; Xian, Y.; Xiong, Z.; Zou, F.; Zou, C.; Gong, W.; Hu, J.; Chen, K.; Pei, X.; Jiang, Z.; Pan, Y. [College of Electrical and Electronic Engineering, HuaZhong University of Science and Technology, WuHan, Hubei 430074 (China)

2009-10-15

16

Self-consistent two-dimensional modeling of cold atmospheric-pressure plasma jets/bullets  

NASA Astrophysics Data System (ADS)

A computational modeling study of streamer propagation in a cold, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, multi-temperature plasma model with detailed finite-rate chemistry and photoionization effects is used to provide fundamental insights into the structure and dynamics of the streamers. A parametric study of the streamer properties as a function of important discharge geometric and operating conditions is performed. The fluid mechanical mixing layer between the helium jet core and the ambient air is instrumental in guiding the propagation direction of the streamer and gives the plasma jet a visibly collimated appearance. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral and nitrogen molecules. Photoionization plays a role in enhancing the propagation speed of the streamer, but is not necessary to sustain the streamer. The streamer yields a large radical concentration through chemical reactions in the streamer head and the body. The streamer propagation speed increases with reduced helium jet radius and increased helium-air mixing layer width. Impurities in the helium jet result in a significant increase in the discharge propagation speed within the tube through photoionization, but not after the streamer propagates into the open ambient region. It is also observed that thinner electrodes produce stronger electric-field concentrations that increase discharge propagation speeds within the tube but have a smaller influence on the discharge after it emerges out of the tube as a streamer.

Breden, D.; Miki, K.; Raja, L. L.

2012-06-01

17

Atmospheric pressure cold plasma treatment of cellulose based fillers for wood plastic composites  

NASA Astrophysics Data System (ADS)

The main challenge of wood plastic composites (WPC) resides in the low interfacial adhesion due to incompatibility between the cellulose based filler that has a polar surface and most common matrixes, polyolefins which are non-polar. Plasma treatment is a promising technique for surface modification and its implementation into the processing of WPC would provide this industry with a versatile and nearly environmentally benign manufacturing tool. Our investigation aims at designing a cold atmospheric pressure plasma reactor for coating fillers with a hydrophobic material prior to compounding with the matrix. Deposition was achieved with our reactor that includes an array of high voltage needles, a grounded metal mesh, Ar as carrier gas and C2H2 as the precursor molecule. Parameters studied have included gas feed rates and applied voltage; FTIR, ESCA, AFM and SEM imaging were used for film diagnostics. We will also report on deposition rate and its dependence on radial and axial position as well as the effects of plasma-polymerized acetylene on the surface free energy of cellulose based substrates.

Lekobou, William; Englund, Karl; Pedrow, Patrick; Scudiero, Louis

2011-11-01

18

Free radicals induced in aqueous solution by non-contact atmospheric-pressure cold plasma  

NASA Astrophysics Data System (ADS)

To understand plasma-induced chemical processing in liquids, we investigated the formation of free radicals in aqueous solution exposed to different types of non-contact atmospheric-pressure helium plasma using the spin-trapping technique. Both hydroxyl radical (OH.) and superoxide anion radical (O2-.) adducts were observed when neutral oxygen gas was additionally supplied to the plasma. In particular, O2-. can be dominantly induced in the solution via oxygen flow into the afterglow gas of helium plasma. This type of plasma treatment can potentially be used in medical applications to control infectious diseases, because the O2-. is crucial for sterilization of liquids via atmospheric-pressure plasma.

Tani, Atsushi; Ono, Yusuke; Fukui, Satoshi; Ikawa, Satoshi; Kitano, Katsuhisa

2012-06-01

19

A simple cold Ar plasma jet generated with a floating electrode at atmospheric pressure  

SciTech Connect

An experimental study is presented of a cold atmospheric Ar plasma jet with distinct advantages of low-working voltage and high plasma stability. To effectively improve the performance of the jet, a pair of pin electrodes with one floating in the air is applied. Variation in the applied voltage and/or the Ar gas flow causes the transition of the jet plasma from ignition, through stable plume to an unstable stage. The characteristics of the jet discharge are also studied by means of the electrical and spectroscopic diagnosis.

Nie Qiuyue; Ren Chunsheng; Wang Dezhen; Zhang Jialiang [State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2008-07-07

20

Influence of helium mole fraction distribution on the properties of cold atmospheric pressure helium plasma jets  

NASA Astrophysics Data System (ADS)

The influence of helium mole fraction distribution in air on the cold atmospheric plasma jets excited by 1.5 kHz rectangular high voltage pulse is studied in this work. Computational fluid dynamics (CFD) with incorporation of large eddy simulation (LES) model is used to simulate the helium mole fraction distribution in air under the helium flow from laminar to turbulent regime with increasing helium outlet velocity. Numerical simulation results are combined with experimental results in order to determine the influence of helium distribution on the cold plasma jets. It reveals that the structure of the helium distribution caused by diffusion or by turbulent mixing in turbulent regime determines the characteristics of the cold plasma jets. On the other hand, the curves of plasma jet length (L) versus helium outlet velocity (V) at different jet diameters (D) are unified in a map of jet Reynolds number (Re = ?He.V.D/?He, where ?He is the helium viscosity constant) versus dimensionless plasma jet length (l = L/D). The map is allowed to predict the flow pattern of helium jet in order to estimate and control the plasma jet length at different jet diameters.

Xiong, Ranhua; Xiong, Qing; Nikiforov, Anton Yu.; Vanraes, Patrick; Leys, Christophe

2012-08-01

21

Atmospheric-pressure cold plasma treatment of contaminated fresh fruit and vegetable slices: inactivation and physiochemical properties evaluation  

NASA Astrophysics Data System (ADS)

A direct-current, atmospheric-pressure air cold plasma microjet (PMJ) was applied to disinfect Salmonella directly deposited on fresh fruit and vegetable slices. Effective inactivation was achieved on sliced fruit and vegetables after 1 s plasma treatment. The physiochemical properties of the slices, such as water content, color parameters, and nutritional content were monitored before and after plasma treatment. It was found that the physiochemical properties changes caused by the plasma were within an acceptable range. Reactive oxygen species, which are believed to be the major bactericidal agents in the plasma, were detected by electron spin resonance spectroscopy and optical emission spectroscopy.

Wang, R. X.; Nian, W. F.; Wu, H. Y.; Feng, H. Q.; Zhang, K.; Zhang, J.; Zhu, W. D.; Becker, K. H.; Fang, J.

2012-10-01

22

An 11 cm long atmospheric pressure cold plasma plume for applications of plasma medicine  

SciTech Connect

In this letter, a room temperature atmospheric pressure plasma jet device is reported. The high voltage electrode of the device is covered by a quartz tube with one end closed. The device, which is driven by a kilohertz ac power supply, is capable of generating a plasma plume up to 11 cm long in the surrounding room air. The rotational and vibrational temperatures of the plasma plume are 300 and 2300 K, respectively. A simple electrical model shows that, when the plasma plume is contacted with a human, the voltage drop on the human is less than 66 V for applied voltage of 5 kV (rms)

Lu Xinpei; Jiang Zhonghe; Xiong Qing; Tang Zhiyuan; Hu Xiwei; Pan Yuan [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2008-02-25

23

Photons and particles emitted from cold atmospheric-pressure plasma inactivate bacteria and biomolecules independently and synergistically.  

PubMed

Cold atmospheric-pressure plasmas are currently in use in medicine as surgical tools and are being evaluated for new applications, including wound treatment and cosmetic care. The disinfecting properties of plasmas are of particular interest, given the threat of antibiotic resistance to modern medicine. Plasma effluents comprise (V)UV photons and various reactive particles, such as accelerated ions and radicals, that modify biomolecules; however, a full understanding of the molecular mechanisms that underlie plasma-based disinfection has been lacking. Here, we investigate the antibacterial mechanisms of plasma, including the separate, additive and synergistic effects of plasma-generated (V)UV photons and particles at the cellular and molecular levels. Using scanning electron microscopy, we show that plasma-emitted particles cause physical damage to the cell envelope, whereas UV radiation does not. The lethal effects of the plasma effluent exceed the zone of physical damage. We demonstrate that both plasma-generated particles and (V)UV photons modify DNA nucleobases. The particles also induce breaks in the DNA backbone. The plasma effluent, and particularly the plasma-generated particles, also rapidly inactivate proteins in the cellular milieu. Thus, in addition to physical damage to the cellular envelope, modifications to DNA and proteins contribute to the bactericidal properties of cold atmospheric-pressure plasma. PMID:24068175

Lackmann, Jan-Wilm; Schneider, Simon; Edengeiser, Eugen; Jarzina, Fabian; Brinckmann, Steffen; Steinborn, Elena; Havenith, Martina; Benedikt, Jan; Bandow, Julia E

2013-12-01

24

Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation  

SciTech Connect

Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

Niemi, K.; O'Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O'Connell, D.; Gans, T. [Centre for Plasma Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)

2012-05-25

25

Plasma decontamination of chemical & biological warfare agents by a cold arc plasma jet at atmospheric pressure  

Microsoft Academic Search

The cold arc plasma jet was introduced to decontaminate chemical and biological warfare (CBW) agents for the application of a portable CBW decontamination system. The cold arc plasma jet is a low temperature, high density plasma that produces highly reactive species such as oxygen atoms and ozone. Moreover, it is possible to maintain stable plasma without He or Ar. The

Man Hyeop Han; Joo Hyun Noh; Ki Wan Park; Hyeon Seok Hwang; Hong Koo Baik

2008-01-01

26

Atmospheric-Pressure Cold Plasmas Used to Embed Bioactive Compounds in Matrix Material for Active Packaging of Fruits and Vegetables  

NASA Astrophysics Data System (ADS)

Active thin film packaging is a technology with the potential to provide consumers with new fruit and vegetable products-if the film can be applied without deactivating bioactive compounds.Atmospheric pressure cold plasma (APCP) processing can be used to activate monomer with concomitant deposition of an organic plasma polymerized matrix material and to immobilize a bioactive compound all at or below room temperature.Aims of this work include: 1) immobilize an antimicrobial in the matrix; 2) determine if the antimicrobial retains its functionality and 3) optimize the reactor design.The plasma zone will be obtained by increasing the voltage on an electrode structure until the electric field in the feed material (argon + monomer) yields electron avalanches. Results will be described using Red Delicious apples.Prospective matrix precursors are vanillin and cinnamic acid.A prospective bioactive compound is benzoic acid.

Fernandez, Sulmer; Pedrow, Patrick; Powers, Joseph; Pitts, Marvin

2009-10-01

27

Cold atmospheric pressure plasma jets as sources of singlet delta oxygen for biomedical applications  

NASA Astrophysics Data System (ADS)

Absolute densities of singlet delta oxygen (SDO) molecules were measured using infrared optical emission spectroscopy in the flowing effluents of two different atmospheric-pressure plasma jets (APPJs): a capacitively coupled radio-frequency-driven jet (rf-APPJ) and a lower frequency kilohertz-driven dielectric barrier discharge jet. The plasma jets were operated in helium, with small admixtures of molecular oxygen (O2 < 2%). High absolute SDO densities of up to 6.2 × 1015 cm-3 were measured at approximately 10 cm downstream. The rf-APPJ seems to be much more efficient in producing SDO. The influence of different parameters, such as gas flows and mixtures and power coupled to the plasmas, on the production of SDO by the two APPJs has been investigated. Despite the considerable differences between the two plasma jets (excitation frequency, electric field direction, inter-electrode distance, plasma propagation), similar dependencies on the oxygen admixture and on the dissipated power were found in both APPJs. However, opposite trends were observed for the gas flow dependence. The results presented in this paper show that the control of the external operating conditions of each APPJ enables the tailoring of the SDO composition of both plasma effluents. This provides scope to tune the plasma jets for desired applications, e.g., in biomedicine.

Sousa, J. S.; Niemi, K.; Cox, L. J.; Algwari, Q. Th.; Gans, T.; O'Connell, D.

2011-06-01

28

Cold atmospheric pressure plasma jets as sources of singlet delta oxygen for biomedical applications  

SciTech Connect

Absolute densities of singlet delta oxygen (SDO) molecules were measured using infrared optical emission spectroscopy in the flowing effluents of two different atmospheric-pressure plasma jets (APPJs): a capacitively coupled radio-frequency-driven jet (rf-APPJ) and a lower frequency kilohertz-driven dielectric barrier discharge jet. The plasma jets were operated in helium, with small admixtures of molecular oxygen (O{sub 2} < 2%). High absolute SDO densities of up to 6.2 x 10{sup 15} cm{sup -3} were measured at approximately 10 cm downstream. The rf-APPJ seems to be much more efficient in producing SDO. The influence of different parameters, such as gas flows and mixtures and power coupled to the plasmas, on the production of SDO by the two APPJs has been investigated. Despite the considerable differences between the two plasma jets (excitation frequency, electric field direction, inter-electrode distance, plasma propagation), similar dependencies on the oxygen admixture and on the dissipated power were found in both APPJs. However, opposite trends were observed for the gas flow dependence. The results presented in this paper show that the control of the external operating conditions of each APPJ enables the tailoring of the SDO composition of both plasma effluents. This provides scope to tune the plasma jets for desired applications, e.g., in biomedicine.

Sousa, J. S.; Niemi, K.; Cox, L. J.; Algwari, Q. Th.; Gans, T.; O'Connell, D. [Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, Northern Ireland (United Kingdom)

2011-06-15

29

In-package atmospheric pressure cold plasma treatment of cherry tomatoes.  

PubMed

Cold plasma is increasingly under research for decontamination of foods, especially fresh fruits and vegetables. The effect of cold plasma on food quality, however, remains under researched. This study investigates the effects of cold plasma generated within a sealed package from a dielectric barrier discharge on the physical quality parameters and respiration rates of cherry tomatoes. Respiration rates and weight loss were monitored continuously, while other parameters are reported at the end of storage period. Differences among weight loss, pH and firmness for control and treated cherry tomatoes were insignificant towards the end of storage life. Changes in respiration rates and colour of tomatoes were recorded as a function of treatment, which were not drastic. The results implicate that cold plasma could be employed as a means for decontamination of cherry tomatoes while retaining product quality. PMID:24650730

Misra, Nrusimha Nath; Keener, Kevin M; Bourke, Paula; Mosnier, Jean-Paul; Cullen, Patrick J

2014-08-01

30

Atmospheric-pressure plasma technology  

Microsoft Academic Search

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

U. Kogelschatz

2004-01-01

31

Assessment of the roles of various inactivation agents in an argon-based direct current atmospheric pressure cold plasma jet  

SciTech Connect

Three types of gases, pure argon (99.999%), argon with 2% oxygen, and argon with 2% oxygen and 10% nitrogen were used as operating gases of a direct current atmospheric pressure cold plasma jet to inactivate Staphylococcus aureus (S. aureus) suspended in a liquid. The inactivation efficacies for the plasma jets operating in the three gases decrease from Ar/O{sub 2}(2%) to Ar/O{sub 2}(2%)/N{sub 2}(10%) to pure Ar. Optical emission spectroscopy, electron spin resonance spectroscopy, high performance liquid chromatography, and atomic absorption spectrophotometry were employed to identify and monitor the reactive species in the plasma-liquid system for the three operating gases and revealed the presence of O, {sup 1}O{sub 2}, OH, NO, H{sub 2}O{sub 2}, O{sub 3}, and NO{sub 3}{sup -}/NO{sub 2}{sup -} as well as Cu{sup +}/Cu{sup 2+}. The S. aureus inactivation results indicate that atomic oxygen (O) is the key inactivation agent, while other species play a lesser role in the inactivation progress studied here.

Zhang Qian; Wang Ruixue [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Sun Peng; Feng Hongqing; Liang Yongdong [College of Engineering, Peking University, Beijing 100871 (China); Zhu Weidong [Department of Applied Science and Technology, Saint Peter's College, New Jersey 07031 (United States); Becker, Kurt H. [Department of Applied Physics, Polytechnic Institute of New York University, New York 11201 (United States); Zhang Jue; Fang Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

2012-06-15

32

An atmospheric-pressure cold plasma leads to apoptosis in Saccharomyces cerevisiae by accumulating intracellular reactive oxygen species and calcium  

NASA Astrophysics Data System (ADS)

A non-thermal plasma is known to induce apoptosis of various cells but the mechanism is not yet clear. A eukaryotic model organism Saccharomyces cerevisiaewas used to investigate the cellular and biochemical regulations of cell apoptosis and cell cycle after an atmospheric-pressure cold plasma treatment. More importantly, intracellular calcium (Ca2+) was first involved in monitoring the process of plasma-induced apoptosis in this study. We analysed the cell apoptosis and cell cycle by flow cytometry and observed the changes in intracellular reactive oxygen species (ROS) and Ca2+ concentration, cell mitochondrial membrane potential (??m) as well as nuclear DNA morphology via fluorescence staining assay. All experimental results indicated that plasma-generated ROS leads to the accumulation of intracellular ROS and Ca2+ that ultimately contribute to apoptosis associated with cell cycle arrest at G1 phase through depolarization of ??m and fragmenting nuclear DNA. This work provides a novel insight into the physical and biological mechanism of apoptosis induced by a plasma which could benefit for promoting the development of plasmas applied to cancer therapy.

Ma, R. N.; Feng, H. Q.; Liang, Y. D.; Zhang, Q.; Tian, Y.; Su, B.; Zhang, J.; Fang, J.

2013-07-01

33

Cold atmospheric pressure plasma treatment of ready-to-eat meat: inactivation of Listeria innocua and changes in product quality.  

PubMed

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 containing 30% oxygen and 70% argon. Treatments resulted in a reduction of L. innocua ranging from 0.8 ± 0.4 to 1.6 ± 0.5 log cfu/g with no significant effects of time and intensity while multiple treatments at 15.5 and 62 W of 20 s with a 10 min interval increased reduction of L. innocua with increasing number of treatments. Concentrations of thiobarbituric acid reactive substances (TBARS) increased with power, treatments and storage time and were significantly higher than those of control samples after 1 and 14 days of storage at 5 °C. However, the levels were low (from 0.1 to 0.4 mg/kg) and beneath the sensory threshold level. Surface colour changes included loss of redness of ?40% and 70% after 1 and 14 days of storage, respectively, regardless of plasma treatment. The results indicate that plasma may be applicable in surface decontamination of pre-packed RTE food products. However, oxidation may constitute an issue in some products. PMID:22265306

Rød, Sara Katrine; Hansen, Flemming; Leipold, Frank; Knøchel, Susanne

2012-05-01

34

Sterilization of bacteria, yeast, and bacterial endospores by atmospheric-pressure cold plasma using helium and oxygen.  

PubMed

Atmospheric-pressure cold plasma (APCP) using helium/oxygen was developed and tested as a suitable sterilization method in a clinical environment. The sterilizing effect of this method is not due to UV light, which is known to be the major sterilization factor of APCP, but instead results from the action of reactive oxygen radicals. Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae deposited on a nitrocellulose filter membrane or Bacillus subtilis spores deposited on polypropylene plates were exposed to helium/oxygen plasma generated with AC input power at 10 kHz, 6 kV. After plasma treatment, nitrocellulose filter membranes were overlaid on fresh solid media and CFUs were counted after incubation overnight. D-values were 18 sec for E. coli, 19 sec for S. aureus, 1 min 55 sec for S. cerevisiae, and 14 min for B. subtilis spores. D-values of bacteria and yeast were dependent on the initial inoculation concentration, while the D-value of B. subtilis spores showed no correlation. When treated cells were observed with a scanning electron microscope, E. coli was more heavily damaged than S. aureus, S. cerevisiae exhibited peeling, and B. subtilis spores exhibited shrunken morphology. Results showed that APCP using helium/oxygen has many advantages as a sterilization method, especially in a clinical environment with conditions such as stable temperature, unlimited sample size, and no harmful gas production. PMID:16820756

Lee, Kyenam; Paek, Kwang-hyun; Ju, Won-Tae; Lee, Yoenhee

2006-06-01

35

Desizing of Starch Containing Cotton Fabrics Using Near Atmospheric Pressure, Cold DC Plasma Treatment  

NASA Astrophysics Data System (ADS)

An attempt has been made to desize the starch containing grey cotton fabrics using the DC plasma with oxygen as the gaseous medium. Process conditions of the plasma reactor were optimized in terms of distance between the plates (3.2 cm), applied voltage (600 V) and applied pressure (0.01 bar) to obtain maximum desizing efficiency. No discolouration was observed in the hot water extracts of the desized sample in presence of iodine though relatively higher solvent extractable impurities (4.53 %) were observed in the plasma desized samples compared to acid desized samples (3.38 %). Also, significant weight loss, improvements in plasma desized samples were observed than that of grey fabrics in terms of drop absorbency.

Prasath, A.; Sivaram, S. S.; Vijay Anand, V. D.; Dhandapani, Saravanan

2013-03-01

36

In vitro efficacy of cold atmospheric pressure plasma on S. sanguinis biofilms in comparison of two test models  

PubMed Central

Dental plaque critically affects the etiology of caries, periodontitis and periimplantitis. The mechanical removal of plaque can only be performed partially due to limited accessibility. Therefore, plaque still represents one of the major therapeutic challenges. Even though antiseptic mouth rinses reduce the extent of biofilm temporarily, plaque removal remains incomplete and continuous usage can even result in side effects. Here we tested argon plasma produced by kinpen09 as one option to inactivate microorganisms and to eliminate plaque. S. sanguinis biofilms cultivated in either the European Biofilm Reactor (EUREBI) or in 24 well plates were treated with argon plasma. In both test systems a homogeneous, good analyzable and stable biofilm was produced on the surface of titan plates within 72 h (>6,9 log10 CFU/ml). Despite the significantly more powerful biofilm production in EUREBI, the difference of 0.4 log10 CFU/ml between EUREBI and the 24 well plates was practically not relevant. For that reason both test models were equally qualified for the analysis of efficacy of cold atmospheric pressure plasma. We demonstrate a significant reduction of the biofilm compared to the control in both test models. After plasma application of 180 s the biofilm produced in EUREBI or in 24 well plates was decreased by 0.6 log10 CFU/ml or 0.5 log10 CFU/ml, respectively. In comparison to recently published studies analyzing the efficacy of kinpen09, S. sanguinis produces a hardly removable biofilm. Future investigations using reduced distances between plasma source and biofilm, various compositions of plasma and alternative plasma sources will contribute to further optimization of the efficacy against S. sanguinis biofilms.

Gorynia, Susanne; Koban, Ina; Matthes, Rutger; Welk, Alexander; Gorynia, Sabine; Hubner, Nils-Olaf; Kocher, Thomas; Kramer, Axel

2013-01-01

37

Tuning Effect of N2 on Atmospheric-Pressure Cold Plasma CVD of TiO2 Photocatalytic Films  

NASA Astrophysics Data System (ADS)

To deposit TiO2 films through plasma CVD, the partial pressure ratio of O2 to TiCl4 should be greater than the stoichiometric ratio (pO2/pTiCl4 > 1). However, this may lead to the formation of powder instead of film on the substrate when using volume dielectric barrier discharge (volume-DBD) at atmospheric pressure. In this study, by adding N2 into the working gas Ar, TiO2 photocatalytic films were successfully fabricated in the presence of excess O2 (pO2/pTiCl4 = 2.6) by using a wire-to-plate atmospheric-pressure volume-DBD. The tuning effect of N2 on the deposition of TiO2 film was studied in detail. The results showed that by increasing the N2 content, the deposition rate and particle size of the TiO2 film were reduced, and its photocatalytic activity was enhanced. The tuning mechanism of N2 is further discussed.

Di, Lanbo; Li, Xiaosong; Zhao, Tianliang; Chang, Dalei; Liu, Qianqian; Zhu, Aimin

2013-01-01

38

FAST TRACK COMMUNICATION: Discharge features of radio-frequency, atmospheric-pressure cold plasmas under an intensified local electric field  

NASA Astrophysics Data System (ADS)

In this paper, stable atmospheric-pressure argon, nitrogen or air glow discharges driven by a radio-frequency power supply with water-cooled, bare copper electrodes are obtained by employing a newly-designed plasma generator. Due to the existence of the intensified local electric field by using an insulated tungsten wire between the two bare copper electrodes, which is also verified by the modelling results, the experimental measurements show that stable glow discharges of argon, nitrogen or air can be obtained following a local breakdown process in the vicinity of the tungsten wire under lower applied voltages between the electrodes.

Li, Guo; Li, He-Ping; Sun, Wen-Ting; Wang, Sen; Tian, Zhe; Bao, Cheng-Yu

2008-10-01

39

Development of an atmospheric-pressure homogeneous and cold Ar/O2 plasma source operating in glow discharge  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure Ar/O2 glow discharge is generated in a parallel bare metal plate reactor with a radio-frequency power supply by introducing a dielectric strip in the inlet of the gas flow. The role of the dielectric strip is discussed experimentally. The allowable oxygen-to-argon ratio reaches 1.0 vol % and the generated Ar/O2 plasma discharge is characterized by a low gas temperature and good spatial homogeneity, implying its feasible application as a type of material treatment for a large-area surface, as illustrated experimentally by the ashing of carbon black.

Li, Shou-Zhe; Wu, Qi; Zhang, Jialiang; Wang, Dezhen; Uhm, Han S.

2010-06-01

40

Atmospheric-pressure plasma technology  

NASA Astrophysics Data System (ADS)

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.

Kogelschatz, U.

2004-12-01

41

Inactivation of Candida Strains in Planktonic and Biofilm Forms Using a Direct Current, Atmospheric-Pressure Cold Plasma Micro-Jet  

NASA Astrophysics Data System (ADS)

A direct-current, atmospheric-pressure, He/O2 (2%) cold plasma ­microjet is applied to Candida species (C. glabrata, C. albicansand C. krusei). Effective inactivation is achieved both in air and in water within 5 min of plasma treatment. Same plasma treatment also successfully inactivated candida biofilms on Petri dish. The inactivation was verified by cell viability test (XTT assay). Severe deformation of Candida biofilms after the plasma treatment was observed through scanning electron microscope (SEM). Optical emission spectroscopy shows strong atomic oxygen emission at 777 nm. Hydroxyl radical (•OH), superoxide anion radical (•O2-) and singlet molecular oxygen (1O2) are detected by electron spin resonance (ESR) spectroscopy. The sessile minimal inhibitory concentrations (SMICs) of fluconazole, amphotericin B, and caspofungin against the Candida spp. biofilms were decreased to 2-6 fold dilutions in plasma microjet treated group in comparison with the controls. This novel approach may become a new tool for the treatment of clinical dermatosis

Zhu, Wei-Dong; Sun, Peng; Sun, Yi; Yu, Shuang; Wu, Haiyan; Liu, Wei; Zhang, Jue; Fang, Jing

42

In situ absolute air, O3 and NO densities in the effluent of a cold RF argon atmospheric pressure plasma jet obtained by molecular beam mass spectrometry  

NASA Astrophysics Data System (ADS)

A molecular beam mass spectrometer has been calibrated and used to measure the air entrainment, nitric oxide and ozone concentrations in the effluent of a cold atmospheric pressure argon RF driven plasma jet. The approaches for calibrating the mass spectrometer for different species are described in detail. Gas phase densities of ozone and nitric oxide up to 7.5 ppm and 4 ppm, respectively, have been measured in the far effluent of the argon plasma jet. The difference in air entrainment when the plasma is undisturbed or is close to a well, which is the case for e.g. in vitro plasma–cell interaction studies, is shown. In addition, an exponential decay of the positive ion flux as a function of distance in the effluent is obtained. Furthermore, the effect of plasma power, duty cycle and air and O2 admixtures introduced into the argon flow on the NO and O3 production is presented, including the possibility of independent control of the NO and O3 flux from the jet.

van Ham, B. T. J.; Hofmann, S.; Brandenburg, R.; Bruggeman, P. J.

2014-06-01

43

1-D fluid model of atmospheric-pressure rf He+O{sub 2} cold plasmas: Parametric study and critical evaluation  

SciTech Connect

In this paper atmospheric-pressure rf He+O{sub 2} cold plasmas are studied by means of a 1-D fluid model. 17 species and 60 key reactions selected from a study of 250+ reactions are incorporated in the model. O{sub 2}{sup +}, O{sub 3}{sup -}, and O are the dominant positive ion, negative ion, and reactive oxygen species, respectively. Ground state O is mainly generated by electron induced reactions and quenching of atomic and molecular oxygen metastables, while three-body reactions leading to the formation of O{sub 2} and O{sub 3} are the main mechanisms responsible for O destruction. The fraction of input power dissipated by ions is {approx}20%. For the conditions considered in the study {approx}6% of the input power is coupled to ions in the bulk and this amount will increase with increasing electronegativity. Radial and electrode losses of neutral species are in most cases negligible when compared to gas phase processes as these losses are diffusion limited due to the large collisionality of the plasma. The electrode loss rate of neutral species is found to be nearly independent of the surface adsorption probability p for p > 0.001 and therefore plasma dosage can be quantified even if p is not known precisely.

Yang Aijun; Wang Xiaohua; Rong Mingzhe; Liu Dingxin [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China); Iza, Felipe [School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom); Kong, Michael G. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China); School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom)

2011-11-15

44

Cold atmospheric plasma in cancer therapy  

SciTech Connect

Recent progress in atmospheric plasmas has led to the creation of cold plasmas with ion temperature close to room temperature. This paper outlines recent progress in understanding of cold plasma physics as well as application of cold atmospheric plasma (CAP) in cancer therapy. Varieties of novel plasma diagnostic techniques were developed recently in a quest to understand physics of CAP. It was established that the streamer head charge is about 10{sup 8} electrons, the electrical field in the head vicinity is about 10{sup 7} V/m, and the electron density of the streamer column is about 10{sup 19} m{sup ?3}. Both in-vitro and in-vivo studies of CAP action on cancer were performed. It was shown that the cold plasma application selectively eradicates cancer cells in-vitro without damaging normal cells and significantly reduces tumor size in-vivo. Studies indicate that the mechanism of action of cold plasma on cancer cells is related to generation of reactive oxygen species with possible induction of the apoptosis pathway. It is also shown that the cancer cells are more susceptible to the effects of CAP because a greater percentage of cells are in the S phase of the cell cycle.

Keidar, Michael; Shashurin, Alex; Volotskova, Olga [Mechanical and Aerospace Engineering, George Washington University, Washington DC 20052 (United States)] [Mechanical and Aerospace Engineering, George Washington University, Washington DC 20052 (United States); Ann Stepp, Mary [Medical School, George Washington University, Washington DC 20052 (United States)] [Medical School, George Washington University, Washington DC 20052 (United States); Srinivasan, Priya; Sandler, Anthony [Childrens National Medical Center, Washington DC 20010 (United States)] [Childrens National Medical Center, Washington DC 20010 (United States); Trink, Barry [Head and Neck Cancer Research Division, Department of Otolaryngology, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205 (United States)] [Head and Neck Cancer Research Division, Department of Otolaryngology, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

2013-05-15

45

Streamer-Like Atmospheric Pressure Plasma Jet (Postprint).  

National Technical Information Service (NTIS)

The properties of an atmospheric pressure plasma jet (APPJ) are examined in a single-cell dielectric capillary configuration. In contrast to some other flow-driven APPJs, this stable, cold plasma jet is electrically driven, composed of rapidly propagating...

B. L. Sands B. N. Ganguly K. Tachibana

2008-01-01

46

Cold Atmosphere Plasma in Cancer Therapy  

NASA Astrophysics Data System (ADS)

Plasma is an ionized gas that is typically generated in high-temperature laboratory conditions. Recent progress in atmospheric plasmas led to the creation of cold plasmas with ion temperature close to room temperature. Areas of potential application of cold atmospheric plasmas (CAP) include dentistry, drug delivery, dermatology, cosmetics, wound healing, cellular modifications, and cancer treatment. Various diagnostic tools have been developed for characterization of CAP including intensified charge-coupled device cameras, optical emission spectroscopy and electrical measurements of the discharge propertied. Recently a new method for temporally resolved measurements of absolute values of plasma density in the plasma column of small-size atmospheric plasma jet utilizing Rayleigh microwave scattering was proposed [1,2]. In this talk we overview state of the art of CAP diagnostics and understanding of the mechanism of plasma action of biological objects. The efficacy of cold plasma in a pre-clinical model of various cancer types (long, bladder, and skin) was recently demonstrated [3]. Both in-vitro and in-vivo studies revealed that cold plasmas selectively kill cancer cells. We showed that: (a) cold plasma application selectively eradicates cancer cells in vitro without damaging normal cells. For instance a strong selective effect was observed; the resulting 60--70% of lung cancer cells were detached from the plate in the zone treated with plasma, whereas no detachment was observed in the treated zone for the normal lung cells under the same treatment conditions. (b) Significantly reduced tumor size in vivo. Cold plasma treatment led to tumor ablation with neighbouring tumors unaffected. These experiments were performed on more than 10 mice with the same outcome. We found that tumors of about 5mm in diameter were ablated after 2 min of single time plasma treatment. The two best known cold plasma effects, plasma-induced apoptosis and the decrease of cell migration velocity can have important implications in cancer treatment by localizing the affected area of the tissue and by decreasing metastasic development. In addition, cold plasma treatment has affected the cell cycle of cancer cells. In particular, cold plasma induces a 2-fold increase in cells at the G2/M-checkpoint in both papilloma and carcinoma cells at about 24 hours after treatment, while normal epithelial cells (WTK) did not show significant differences. It was shown that reactive oxygen species metabolism and oxidative stress responsive genes are deregulated. We investigated the production of reactive oxygen species (ROS) with cold plasma treatment as a potential mechanism for the tumor ablation observed. [4pt] [1] Shashurin A., Shneider M.N., Dogariu A., Miles R.B. and Keidar M. Appl. Phys. Lett. (2010) 96, 171502.[0pt] [2] Shashurin A., Shneider M.N., Keidar M. Plasma Sources Sci. Technol. 21 (2012) 034006.[0pt] [3]. M. Keidar, R. Walk, A. Shashurin, P. Srinivasan, A. Sandler, S. Dasgupta , R. Ravi, R. Guerrero-Preston, B. Trink, British Journal of Cancer, 105, 1295-1301, 2011

Keidar, Michael

2012-10-01

47

Microwave Atmospheric-Pressure Sensor  

NASA Technical Reports Server (NTRS)

Report describes tests of microwave pressure sounder (MPS) for use in satellite measurements of atmospheric pressure. MPS is multifrequency radar operating between 25 and 80 GHz. Determines signal absorption over vertical path through atmosphere by measuring strength of echoes from ocean surface. MPS operates with cloud cover, and suitable for use on current meteorological satellites.

Flower, D. A.; Peckham, G. E.; Bradford, W. J.

1986-01-01

48

Ambient air particle transport into the effluent of a cold atmospheric-pressure argon plasma jet investigated by molecular beam mass spectrometry  

NASA Astrophysics Data System (ADS)

Ambient air species, which are transported into the active effluent of an atmospheric-pressure plasma jet result in highly reactive oxygen and nitrogen species (RONS). Especially for the envisaged application field of plasma medicine, these RONS are responsible for strong biological responses. In this work, the effect of ambient air transport into the effluent of an atmospheric-pressure plasma argon jet on the on-axis densities of nitrogen, oxygen and argon was investigated by means of absolutely calibrated molecular beam mass spectrometry (MBMS). According to biomedical experiments a (bottomless) Petri dish was installed in front of the MBMS. In the following, the near flow field is referring to the region close to the nozzle exit and the far flow field is referring to the region beyond that. The absolute on-axis densities were obtained by three different methods, for the near flow field with VUV-absorption technique, for the far flow field with the MBMS and the total flow field was calculated with a computational fluid dynamics (CFD) simulation. The results of the ambient air particle densities of all independent methods were compared and showed an excellent agreement. Therefore the transport processes of ambient air species can be measured for the whole effluent of an atmospheric-pressure plasma jet. Additionally, with the validation of the simulation it is possible in future to calculate the ambient species transport for various gas fluxes in the same turbulent flow regime. Comparing the on-axis densities obtained with an ignited and with a non-ignited plasma jet shows that for the investigated parameters, the main influence on the ambient air species transport is due to the increased temperature in the case when the jet is switched on. Moreover, the presence of positive ions (e.g. ArN_{2}^{+} ) formed due to the interaction of plasma-produced particles and ambient air species, which are transported into the effluent, is shown.

Dünnbier, M.; Schmidt-Bleker, A.; Winter, J.; Wolfram, M.; Hippler, R.; Weltmann, K.-D.; Reuter, S.

2013-10-01

49

Sterilization effects of atmospheric cold plasma brush  

Microsoft Academic Search

This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0×104-1.0×105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and\\/or Ar+O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma

Q. S. Yu; C. Huang; F.-H. Hsieh; H. Huff; Yixiang Duan

2006-01-01

50

Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua  

Microsoft Academic Search

Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC

Estefanía Noriega; Gilbert Shama; Adriana Laca; Mario Díaz; Michael G. Kong

2011-01-01

51

Feed gas humidity: a vital parameter affecting a cold atmospheric-pressure plasma jet and plasma-treated human skin cells  

NASA Astrophysics Data System (ADS)

In this study, the effect of feed gas humidity on the reactive component generation of an atmospheric-pressure argon plasma jet and its effect on human skin cells are investigated. Feed gas humidity is identified as one key parameter that strongly influences stability and reproducibility of plasma medical studies. The plasma jet is investigated by absorption spectroscopy in the ultraviolet and infrared spectral region for its ozone production depending on the humidity concentration in the feed gas. By optical emission spectroscopy the dependence of present excited plasma species such as hydroxyl radicals, molecular nitrogen, argon and atomic oxygen on the feed gas humidity is investigated. As an interface layer between the plasma jet effluent and the biological cell, a buffer solution is treated and the hydrogen peroxide (H2O2) production is studied with two independent colorimetric assays as a function of humidity admixture to the feed gas. Ultimately, the effect of varying feed gas humidity on the cell viability of indirect plasma treated adherent HaCAT cells is investigated. The highest viability is found for the driest feed gas condition. Furthermore, this work shows answers for the relevance of unwanted—or intended—feed gas humidity in plasma medical experiments and their comparatively large relevance with respect to ambient humidity. The findings will lead to more reproducible experiments in the field of plasma medicine.

Winter, J.; Wende, K.; Masur, K.; Iseni, S.; Dünnbier, M.; Hammer, M. U.; Tresp, H.; Weltmann, K.-D.; Reuter, S.

2013-07-01

52

Microplasma jet at atmospheric pressure  

SciTech Connect

A nitrogen microplasma jet operated at atmospheric pressure was developed for treating thermally sensitive materials. For example, the plasma sources in treatment of vulnerable biological materials must operate near the room temperature at the atmospheric pressure, without any risk of arcing or electrical shock. The microplasma jet device operated by an electrical power less than 10 W exhibited a long plasma jet of about 6.5 cm with temperature near 300 K, not causing any harm to human skin. Optical emission measured at the wide range of 280-800 nm indicated various reactive species produced by the plasma jet.

Hong, Yong Cheol; Uhm, Han Sup [Department of Molecular Science and Technology, Ajou University, San 5, Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of)

2006-11-27

53

Laser electrospray mass spectrometry of adsorbed molecules at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Atmospheric pressure mass analysis of solid phase biomolecules is performed using laser electrospray mass spectrometry (LEMS). A non-resonant femtosecond duration laser pulse vaporizes native samples at atmospheric pressure for subsequent electrospray ionization and transfer into a mass spectrometer. LEMS was used to detect a complex molecule (irinotecan HCl), a complex mixture (cold medicine formulation with active ingredients: acetaminophen, dextromethorphan HBr and doxylamine succinate), and a biological building block (deoxyguanosine) deposited on steel surfaces without a matrix molecule.

Brady, John J.; Judge, Elizabeth J.; Simon, Kuriakose; Levis, Robert J.

2010-02-01

54

Atmospheric pressure plasma jet applications  

Microsoft Academic Search

Summary form only given. 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\\/H2 O) which flows between two concentric cylindrical electrodes: an outer grounded electrode and an inner electrode powered at 13.56 MHz RF. While

H. W. Herrmann; L. Henins; G. S. Selwyn

1998-01-01

55

Sterilization effects of atmospheric cold plasma brush  

NASA Astrophysics Data System (ADS)

This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0×104-1.0×105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar+O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy.

Yu, Q. S.; Huang, C.; Hsieh, F.-H.; Huff, H.; Duan, Yixiang

2006-01-01

56

Atmospheric-pressure guided streamers for liposomal membrane disruption  

NASA Astrophysics Data System (ADS)

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.

Svarnas, P.; Matrali, S. H.; Gazeli, K.; Aleiferis, Sp.; Clément, F.; Antimisiaris, S. G.

2012-12-01

57

Atmospheric-pressure plasma jet  

DOEpatents

Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

Selwyn, Gary S. (Los Alamos, NM)

1999-01-01

58

Determining Atmospheric Pressure Using a Water Barometer  

ERIC Educational Resources Information Center

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…

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

2012-01-01

59

Atmospheric-pressure plasma jet  

SciTech Connect

A {gamma}-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250 C at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region there between. A jet of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

Selwyn, G.S.

1999-10-05

60

Radio frequency hollow cathode source for large area cold atmospheric plasma applications  

Microsoft Academic Search

A new type of radio frequency (rf) large area non equilibrium (‘cold’) plasma source operating at atmospheric gas pressures in an open reactor was presented. The source was based on a specially designed rf electrode with the gas flowing through an inner microstructure integrated in the electrode. A cylindrical source of 35 mm in diameter with approximately 900 hollow cathodes

L Bárdoš; H Baránková

2000-01-01

61

Contact-free cold atmospheric plasma treatment of Deinococcus radiodurans.  

PubMed

In this study we investigated the sensitivity of Deinococcus radiodurans to contact-free cold atmospheric plasma treatment as part of a project to establish new efficient procedures for disinfection of inanimate surfaces. The Gram-positive D. radiodurans is one of the most resistant microorganisms worldwide. Stationary phases of D. radiodurans were exposed to cold atmospheric plasma for different time intervals or to ultraviolet C (UVC) radiation at dose rates of 0.001-0.0656 J cm?², respectively. A methicillin-resistant Staphylococcus aureus strain (MRSA) served as control for Gram-positive bacteria. The surface microdischarge plasma technology was used for generation of cold atmospheric plasma. A plasma discharge was ignited using ambient air. Surprisingly, D. radiodurans was sensitive to the cold atmospheric plasma treatment in the same range as the MRSA strain. Survival of both bacteria decreased with increasing plasma exposure times up to 6 log?? cycles (>99.999 %) within 20 s of plasma treatment. In contrast, UVC radiation of both bacteria demonstrated that D. radiodurans was more resistant to UVC treatment than MRSA. Cold atmospheric plasma seems to be a promising tool for industrial and clinical purposes where time-saving is a critical point to achieve efficient disinfection of inanimate surfaces and where protection from corrosive materials is needed. PMID:22584820

Maisch, Tim; Shimizu, Tetsuji; Mitra, Anindita; Heinlin, Julia; Karrer, Sigrid; Li, Yang-Fang; Morfill, Gregor; Zimmermann, Julia L

2012-09-01

62

Atmospheric composition of cold super-Earths  

NASA Astrophysics Data System (ADS)

Planets of masses below 10 times that of Earth (so-called Super-Earths) orbiting far away from their central star have been discovered by Microlensing surveys. Super-Earth atmospheres cannot be characterized remotely yet. However, based on climate modelling and analogies with our solar system, we can put constraints on possible atmospheric compositions. Whenever the triple point of a gaseous constituent is reached on the surface, this constituent is likely to freeze out until equilibrium between ice and vapour/liquid is reached. Important greenhouse gases which are essential for habitability considerations are water (triple point 6.5 mb, 273 K) and carbon dioxide (triple point 5.18 bar, 216 K). In our work we apply a 1D radiative-convective model to Super-Earth atmospheres. We investigate the effect of varying orbital distance, stellar type and planetary mass upon the ability of water and carbon dioxide to remain in the atmosphere. Our results indicate a threshold regime where atmospheres switch from being CO2-rich to being N2-dominated. Implications for habitability and surface conditions are discussed.

von Paris, P.; Patzer, B.; Grenfell, J. L.; Hedelt, P.; Stracke, B.; Rauer, H.

2008-09-01

63

Temporal behavior of cold atmospheric plasma jet  

SciTech Connect

Temporally resolved evolution of parameters in atmospheric plasma jet is studied by means of microwave scattering, fast photographing, and measuring of jet currents. It is observed that streamer ('plasma bullet') propagating along with gas flow is generated immediately after the breakdown. It is demonstrated that an afterglow plasma column remains on the way of streamer passing. Lifetime of the afterglow plasma column is 3-5 {mu}s, which is longer than that of the streamer.

Shashurin, A.; Keidar, M. [Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, George Washington University, Washington, DC 20052 (United States); Shneider, M. N.; Dogariu, A.; Miles, R. B. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2009-06-08

64

Effect of the atmospheric pressure nonequilibrium plasmas on the conformational changes of plasmid DNA  

Microsoft Academic Search

The cold atmospheric pressure plasma, which has been widely used for biomedical applications, may potentially affect the conformation of DNA. In this letter, an atmospheric pressure plasma plume is used to investigate its effects on the conformational changes of DNA of plasmid pAHC25. It is found that the plasma plume could cause plasmid DNA topology alteration, resulting in the percentage

Xu Yan; Fei Zou; Xin Pei Lu; Guangyuan He; Meng Jun Shi; Qing Xiong; Xuan Gao; Zilan Xiong; Yin Li; Feng Yun Ma; Men Yu; Chang Dong Wang; Yuesheng Wang; Guangxiao Yang

2009-01-01

65

Hydrogasification of Carbon in an Atmospheric Pressure Microwave Plasma  

Microsoft Academic Search

Hydrogasification of carbon (C + 2H2 rarr CH4) was studied using a microwave plasma in atmospheric pressure Ar\\/H2 mixtures. When the activated Ar\\/H2 gas stream interacted with cold carbon particles downstream of the microwave cavity, CH4 (methane) was the only stable gasification product, as measured by gas chromatography. However, when carbon particles were injected into the plasma within the microwave

Yongho Kim; Sara Abbate; Hans Ziock; Graydon K. Anderson; Louis A. Rosocha

2007-01-01

66

Does low atmospheric pressure independently trigger migraine?  

PubMed

Although atmospheric weather changes are often listed among the common migraine triggers, studies to determine the specific weather component(s) responsible have yielded inconsistent results. Atmospheric pressure change produces air movement, and low pressure in particular is associated with warm weather, winds, clouds, dust, and precipitation, but how this effect might generate migraine is not immediately obvious. Humans are exposed to low atmospheric pressure in situations such as ascent to high altitude or traveling by airplane in a pressurized cabin. In this brief overview, we consider those conditions and experimental data delineating other elements in the atmosphere potentially related to migraine (such as Saharan dust). We conclude that the available data suggest low atmospheric pressure unaccompanied by other factors does not trigger migraine. PMID:21906054

Bolay, Hayrunnisa; Rapoport, Alan

2011-10-01

67

Biomedical applications and diagnostics of atmospheric pressure plasma  

NASA Astrophysics Data System (ADS)

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 spores.

Petrovi?, Z. Lj; Pua?, N.; Lazovi?, S.; Maleti?, D.; Spasi?, K.; Malovi?, G.

2012-03-01

68

Surface Treatment using Atmospheric Pressure Plasma  

NASA Astrophysics Data System (ADS)

Kogoma and coworkers previously reported that a homogenous glow plasma can be sustained using a barrier-type electrode system in an atmospheric pressure He gas. This approach succeeded in the surface treatment of industrial plastic films and deposition of solid substances that have usually treated in the low pressure glow plasma system. So, the use of atmospheric pressure glow plasma (APG) system should reduce the costs of plasma treatment for many kinds of the solid materials. In the review, at first, the basic theory of the atmospheric-pressure glow plasma will be introduced to explain how to attain the homogenous glow plasma in high pressure condition. Then, the prospects will be presented for different styles of low temperature atmospheric pressure plasma systems. In the final part, some application studies such as organic film deposition, silica film deposition and surface treatment of liquid crystal polymer using APG plasma will be shown.

Kogoma, Masuhiro

69

Prospects for Treating Foods with Cold Atmospheric Gas Plasmas  

NASA Astrophysics Data System (ADS)

In this review the potential applications of cold atmospheric gas plasmas are presented with particular reference to the problems of contamination of foods by biological agents. In addition to the accidental contamination of food, the very real threat arising from the deliberate contamination of the human food chain is also considered. The evidence that has been gained for the efficacy of cold plasmas in inactivating a wide range of biological agents is briefly surveyed. This is followed by an examination of previous work in which ­various types of foodstuffs have been successfully treated using cold gas plasmas. The need to demonstrate that the quality attributes of treated foods is not adversely affected is stressed. Finally, the role which gas plasmas may have in decontaminating food processing equipment is considered.

Shama, Gilbert; Kong, Michael G.

70

Investigating high mortality during the cold season: mapping mean weather patterns of temperature and pressure  

NASA Astrophysics Data System (ADS)

Due to a number of complicating factors, cold-related mortality has long been understudied. Through a synoptic climatological, environment-to-circulation perspective, this research takes a unique approach in examining anomalous surface temperature and pressure map patterns associated with the days leading up to high-mortality, spike days for Chicago, Illinois during the cold season. Atmospheric conditions leading to spike days during the cold season were evaluated through both seasonal anomaly and 1-day anomaly maps. Results indicate that high-mortality days are typically preceded by unseasonably cold weather situated over the region from 2 to 5 days beforehand, with significantly higher than average pressure 1 to 2 days before a mortality spike. As this system moves eastward, a significant 1-day warming trend accompanying a significant drop in sea level pressure follows—occurring on the day of the mortality spike or 1 day prior. Both scenarios—cold, high pressure air exposure and the rapid change in weather—are consistent with previous literature connecting them as factors contributing to cold-related mortality increases, with this sequence possibly playing a key role in yielding mortality levels anomalous enough to meet the threshold for a spike.

Allen, Michael J.; Lee, Cameron C.

2014-01-01

71

Air plasma jet with hollow electrodes at atmospheric pressure  

SciTech Connect

Atmospheric-pressure plasma jet with air is produced through hollow electrodes and dielectric with a hole of 1 mm diam. The plasma jet device is operated by injecting pressurized air into the electrode hole. The air plasma jet device at average powers less than 5 W exhibits a cold plasma jet of about 2 cm in length and near the room temperature, being low enough to treat thermally sensitive materials. Preliminary studies on the discharge characteristics and application tests are also presented by comparing the air plasma jet with the nitrogen and argon plasma jet.

Hong, Yong Cheol; Uhm, Han Sup [Department of Molecular Science and Technology, Ajou University, San 5, Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of)

2007-05-15

72

Pressure Field Study of the Tevatron Cold Compressors  

NASA Astrophysics Data System (ADS)

The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations. The compressor is designed to pump 60 g/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g/sec. Operating speeds are between 40,000 and 95,000 rpm, with a speed of 80,000 rpm at the design point. Different heat loads and magnet quench performance of each of the twenty-four satellite refrigerators dictates different process pressure and flow rates of the cold compressors. Reducing the process flow rate can cause the centrifugal cold compressor to stop pumping and subsequently surge. Tests have been conducted at the Cryogenic Test Facility at Fermilab to map the pressure field and appropriate efficiency of the IHI hydrodynamic cold compressor. The information allows tuning of each of the twenty-four Tevatron satellite refrigerators to avoid cold compressor operation near the surge and choke lines. A new impeller has also been tested. The Tevatron cold compressor pressure field and efficiency data with the new impeller are presented in this paper.

Klebaner, A. L.; Martinez, A.; Soyars, W. M.; Theilacker, J. C.

2004-06-01

73

Pressure Field Study of the Tevatron Cold Compressors  

SciTech Connect

The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations. The compressor is designed to pump 60 g/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g/sec. Operating speeds are between 40,000 and 95,000 rpm, with a speed of 80,000 rpm at the design point. Different heat loads and magnet quench performance of each of the twenty-four satellite refrigerators dictates different process pressure and flow rates of the cold compressors. Reducing the process flow rate can cause the centrifugal cold compressor to stop pumping and subsequently surge. Tests have been conducted at the Cryogenic Test Facility at Fermilab to map the pressure field and appropriate efficiency of the IHI hydrodynamic cold compressor. The information allows tuning of each of the twenty-four Tevatron satellite refrigerators to avoid cold compressor operation near the surge and choke lines. A new impeller has also been tested. The Tevatron cold compressor pressure field and efficiency data with the new impeller are presented in this paper.

Klebaner, A.L.; Martinez, A.; Soyars, W.M.; Theilacker, J.C. [Fermi National Accelerator Laboratory, Batavia, IL, 60510 (United States)

2004-06-23

74

Application of Atmospheric Pressure Ionization Mass Spectrometry.  

National Technical Information Service (NTIS)

The laboratory has developed atmospheric pressure ionization mass spectrometry and applied the technique in several different areas. Research probing the stabilities of phenoxide anions was carried out. The formation of phenoxide anions is an important cl...

R. K. Mitchum

1981-01-01

75

Atmospheric Pressure RF Capacitive Plasma Source  

Microsoft Academic Search

An atmospheric pressure plasma source has been developed and it exhibits many desirable properties for a wide range of plasma applications without the complication and expense of an attached vacuum system. An atmospheric pressure plasma jet (APPJ) operates with rf power and produces a alpha-mode capacitive discharge that is stable, steady-state, and non-thermal. The plasma parameters of this source have

Jaeyoung Park; Ivars Henins; Hans W. Herrmann; Gary S. Selwyn

2000-01-01

76

[Characterization of an atmospheric pressure DC microplasma jet].  

PubMed

In the present work, a simply designed and easy made micrometer plasma jet device operating under atmospheric pressure was characterized. The microplasma jet operates in many kinds of working gas at atmospheric pressure, such as Ar, He, N2 etc, and is powered by a direct current power source. It can generate high current density glow discharge. In order to identify various excited species generated by the direct current microplasma jet device, the optical emission spectra of the jet with argon or nitrogen as working gas were studied. Based on the optical emission spectroscopy analysis of argon microplasma jet, the electron excitation temperature was determined to be about 3 000 K by the intensity ratio of two spectral lines. It is much lower than the electron excitation temperature of atmospheric pressure plasma torch, and hints that the atmospheric pressure direct current microplasma jet is cold compared with the atmospheric pressure plasma torch. The emission spectra of the N2 second positive band system were used to determine the vibrational temperature of the atmospheric pressure direct current microplasma jet. The experimental result shows that the molecular vibrational temperature of N2 is about 2 500 K. The electron density of the microplasma jet is about 10(13) cm(-3), which can be estimated from the electrical parameters of the discharge in the microplasma jet. A simple example of application of the microplasma jet is given. General print paper surface was modified with the microplasma jet and afterwards a droplet test was carried out. It was shown that the microplasma jet is more efficient in changing the hydrophilicity of general print paper. PMID:19445187

Zheng, Pei-Chao; Wang, Hong-Mei; Li, Jian-Quan; Han, Hai-Yan; Xu, Guo-Hua; Shen, Cheng-Yin; Chu, Yan-Nan

2009-02-01

77

Linear arrays of stable atmospheric pressure microplasmas  

SciTech Connect

Microdischarges produce cold atmospheric plasma when the discharge current is limited by the quenching of a microwave resonator. A quarter-wavelength microstripline resonator is shown to support stable atmospheric microplasma in pure argon. Electrical characterization of the microplasma shows that its impedance is resistive and capacitive (Z{sub p}=500-j900 {omega}). An array of these linear resonators generates a stable, line-shaped microplasma operating from a single power source due to close-coupling among adjacent resonators. Both simulations and experiments confirm that coupled-mode theory describes the collective behavior of linear microplasma arrays.

Zhang Zhibo; Hopwood, Jeffrey [Tufts University, Medford, Massachusetts 02155 (United States)

2009-10-19

78

Linear arrays of stable atmospheric pressure microplasmas  

NASA Astrophysics Data System (ADS)

Microdischarges produce cold atmospheric plasma when the discharge current is limited by the quenching of a microwave resonator. A quarter-wavelength microstripline resonator is shown to support stable atmospheric microplasma in pure argon. Electrical characterization of the microplasma shows that its impedance is resistive and capacitive (Zp=500-j900 ?). An array of these linear resonators generates a stable, line-shaped microplasma operating from a single power source due to close-coupling among adjacent resonators. Both simulations and experiments confirm that coupled-mode theory describes the collective behavior of linear microplasma arrays.

Zhang, Zhi-Bo; Hopwood, Jeffrey

2009-10-01

79

Apparatus for Cold, Pressurized Biogeochemical Experiments  

NASA Technical Reports Server (NTRS)

A laboratory apparatus has been devised as a means of studying plausible biogeochemical reactions under high-pressure, low-temperature aqueous, anaerobic conditions like those conjectured to prevail in a liquid water ocean on Europa (the fourth largest moon of the planet Jupiter). The experiments to be performed by use of this apparatus are intended to enhance understanding of how life (if any) could originate and evolve in the Europa ocean environment. Inasmuch as terrestrial barophilic, psychrophilic organisms that thrive under anaerobic conditions are used in the experiments, the experiments may also contribute to terrestrial biogeochemistry. The apparatus (see figure) includes a bolt-closure reaction vessel secured inside a refrigerator that maintains a temperature of 4 C. Pressurized water is supplied to the interior of the vessel by a hydrostatic pump, which is attached to the vessel via high-pressure fittings. The terrestrial organisms used in the experiments thus far have been several facultative barophilic, psychrophilic stains of Shewanella bacteria. In the experiments, these organisms have been tested for reduction of ferric ion by growing them in the presence of a ferric food source under optimized terrestrial conditions. The short-term goal of these experiments has been to select Shewanella strains that exhibit iron-reduction capability and test their ability to facilitate biogeochemical reduction of iron under temperature and pressure conditions imitating those in Europa s ocean. It is anticipated, that, once growth under Europa-like conditions has been achieved, the selected Shewanella strains will be used to facilitate biogeochemical reactions of sulfate and carbonate with hydrogen gas. Any disequilibrium of the products with the environment would be interpreted as signifying biogenic activity and the possibility of life in Europa s ocean.

Amashukeli, Xenia; Pappalardo, Robert T.; Connon, Stephanie A.; Gleeson, Damhnait F.

2010-01-01

80

Living tissue under treatment of cold plasma atmospheric jet  

SciTech Connect

The interaction of the cold atmospheric plasma jet with fibroblast cells was studied. Plasma jet was initiated in the helium flow blowing through the syringe by application of high ac voltage to the discharge electrodes. The plasma jet had a length of 5 cm and a diameter of 1.5-2 mm in ambient air. Treatment of cells with plasma jet resulted in decreasing of cell migration rate, cell detachment, and appearance of ''frozen'' cells, while treatment with helium flow (no plasma) resulted in appearance of frozen cells only. A variety of cellular responses was explained by different intensities of treatment.

Shashurin, A.; Keidar, M.; Bronnikov, S. [Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, The George Washington University, Washington, District of Columbia 20052 (United States); Jurjus, R. A.; Stepp, M. A. [Department of Anatomy and Regenerative Biology, George Washington University Medical School, The George Washington University, Washington, District of Columbia 20052 (United States)

2008-11-03

81

Friction and wear properties of Ti6Al4V/WC-Co in cold atmospheric plasma jet  

NASA Astrophysics Data System (ADS)

The friction and wear properties of Ti6Al4V/WC-Co friction pair were studied using an autonomous atmospheric pressure bare electrode cold plasma jet generating device and block-on-ring friction/wear tester, respectively. The study was conducted under air, air jet, nitrogen jet, air cold plasma jet, and nitrogen cold plasma jet atmospheres. Both nitrogen cold and air cold plasma jets effectively reduced the friction coefficients of the friction pairs and decreased friction temperature. The friction coefficient in the nitrogen cold plasma jet decreased to almost 60% compared with that in the air. The scanning electron microscope, energy-dispersive X-ray spectroscope, and X-ray diffraction analyses illustrated that adhesive wear was relieved and the friction surfaces of Ti6Al4V were smoother, both in the nitrogen cold and air cold plasma jets. The roughness value Ra of the Ti6Al4V friction surfaces can reach 1.107 ?m. A large number of nitrogen particles in the ionic and excited states contained by cold plasma jets reacts easily on the friction surface to produce a large amount of nitrides, which can excellently reduce the wear of Ti6Al4V/WC-Co friction pairs in real-time.

Xu, Wenji; Liu, Xin; Song, Jinlong; Wu, Libo; Sun, Jing

2012-10-01

82

General Overview of Cold Pressure Processes for Joining Aluminium  

Microsoft Academic Search

The paper presents a brief overview on several researches developed in the Pressure Welding Laboratory, Robotics of Welding Department - Dunarea de Jos University of Galati, Romania. After the necessary Introduction in the subject, considerations on Joining Aluminium Processes Classifications are presented, including an overview on the main joining processes used for aluminium. Several aspects of Aluminium cold welding processes

Danut IORDACHESCU; Bogdan Georgescu; Mihaela IORDACHESCU

83

Pressure bump instability in very large cold bore storage rings  

SciTech Connect

Calculations have been done to estimate the circulating current necessary to induce the onset of a pressure bump instability in a cold bore storage ring. For a wide range of storage ring parameters, the instability threshold current is more than an order of magnitude higher than the operating current. 4 references, 2 tables.

Limon, P.

1983-12-01

84

Biomedical Applications of the Cold Atmospheric Plasma: Cell Responses  

NASA Astrophysics Data System (ADS)

Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. Depending on the configuration the cold plasma sources can be used in the following areas: wound healing, skin diseases, hospital hygiene, sterilization, antifungal treatments, dental care, cosmetics targeted cell/tissue removal, and cancer treatments. This dissertation is focused on the studies of biomedical applications of cold atmospheric plasma jet based on helium flow and resultant cell responses to the cold plasma treatment. The studies were carried out on extra-cellular and intra-cellular levels in vitro. The main practical applications are wound healing and alternative to existing cancer therapy methods, areas of great interest and significant challenges. The CAP jet was built in the Micropropulsion and Nanotechnology Laboratory of Dr. Michael Keidar, as a part of multidisciplinary collaboration with the GW Medical School (Dr. M.A. Stepp) concerned with plasma medicine and bioengineering studies. Normal and cancer cells have two fundamental behavioral properties, proliferation and motility, which can be evaluated through cell migration rates and cell cycle progression. Various microscopic, spectroscopic and flow cytometry techniques were used to characterize cell responses to the cold plasma treatment. It was found that CAP effect on the cells is localized within the area of the treatment (of around ˜ 5mm in diameter). The migration rates of the normal skin cells can be reduced up to ˜ 40%. However, depending on the cell type the required treatment time is different, thus differential treatment of various cells presented in tissue is possible. The CAP effect on the migration was explained through the changes of the cell surface proteins/integrins. It was also found that normal and cancer cells respond differently to the CAP treatment under the same experimental conditions. CAP is currently being evaluated as a new highly selective alternative addition to existing cancer therapies. It was shown that the increased sensitivity of cancer cells to CAP treatment is caused by differences in the distribution of cancer cells and normal cells within the cell cycle. It was also shown that the expression of ?H2A.X (pSer139), an oxidative stress reporter indicating S-phase damage, is enhanced specifically within CAP treated cells in the S phase of the cell cycle together with significant decrease in EdU-signal of DNA-replicating cells. Thus, newly developed CAP technology was proven to be of a great interest for practical applications in the areas of wound healing and cancer treatment. The identification and explanation of the mechanisms by which CAP affects the cells was presented.

Volotskova, Olga

85

A streamer-like atmospheric pressure plasma jet  

SciTech Connect

The properties of an atmospheric pressure plasma jet (APPJ) are examined in a single-cell dielectric capillary configuration. In contrast to some other flow-driven APPJs, this stable, cold plasma jet is electrically driven, composed of rapidly propagating ionization fronts with speeds of the order of 10{sup 7} cm/s. Using spatially and temporally resolved optical diagnostics, it is demonstrated that the plasma jet is initiated independent of the dielectric barrier discharge inside the capillary. It is also shown that the properties and dynamics of this APPJ are directly analogous to those of positive corona streamer discharges.

Sands, Brian L. [UES, Inc., 2645 5th St., Wright Patterson Air Force Base, Ohio 45433-7251 (United States); Ganguly, Biswa N. [Air Force Research Laboratory, 2645 5th St., Wright Patterson Air Force Base, Ohio 45433-7251 (United States); Tachibana, Kunihide [Department of Electronic Science and Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

2008-04-14

86

Intraseasonal Cold Air Outbreak over East Asia and the preceding atmospheric condition over the Barents-Kara Sea  

NASA Astrophysics Data System (ADS)

Frequent occurrence of cold air outbreak is a dominant feature of the East Asian winter monsoon. A contributing factor for the this cold air outbreak is the role of stationary Rossby waves over the Eurasian continent which intensifies the surface Siberian High and the accompanying cold air outflow. Reduced sea ice and increase in turbulence heat flux is hypothesized as a source of such stationary waves (Honda et al. 2009). In particular, the winter of 2009/2010 saw a strong correlation of high pressure anomaly over the Barents/Kara sea and the following cold air buildup over the Eurasian continent and its advection towards East Asia (Hori et al. 2011). The lag correlation of surface temperature over Japan and the 850hPa geopotential height shows a cyclonic anomaly appearing over the Barents/Kara sea which creates a cold air advection over the Eurasian continent. The pressure anomaly subsequently shifted westward to mature into a blocking high which created a wave- train pattern downstream advecting the cold air buildup eastward toward East Asia and Japan (Fig1). We further examine this mechanism for other years including the 2005/2006, 2010/2011 winter and other winters with extreme cold air outbreaks. Overall, the existence of an anticyclonic anomaly over the Barents/Kara sea correlated well with the seasonal dominance of cold air over the Eurasian continent thereby creating a contrast of a warm Arctic and cold Eurasian continent.In the intraseasonal timescale, the existence of this anticyclone corresponds to a persisting atmospheric blocking in the high latitudes. In the presentation, we address the underlying chain of events leading up to a strong cold air outbreak over East Asia from an atmosphere - sea ice - land surafce interaction point of view for paritular cold winter years.

Hori, M. E.; Inoue, J.

2011-12-01

87

Double-Layered Atmospheric Pressure Plasma Jet  

NASA Astrophysics Data System (ADS)

In this paper, we present a double-layered atmospheric pressure plasma jet (DLAPPJ) that is expected to improve conventional single-layered atmospheric pressure plasma jets. With the additional introduction of nitrogen gas into the outer nozzle between the inner and outer tubes, the plasma plume is boosted, resulting in a brighter and longer plasma torch, which may have more radicals and which may broaden the application range of atmospheric pressure plasma jets. The characteristics of the proposed device were investigated with the measurement of the visible torch length, wettability tests and optical emission spectroscopy. The results obtained imply that the DLAPPJ can be used for target-based plasma treatments, that is, (a) oxidation-related applications, such as surface treatment, biological decontamination and apoptosis induction, and (b) nitrification-related applications such as NO generation for wound healing and surface modification, by controlling radicals in plasmas.

Choi, Jaegu; Matsuo, Keita; Yoshida, Hidekazu; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori

2009-08-01

88

Atmospheric Pressure Plasma Process And Applications  

SciTech Connect

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmosphericpressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

Peter C. Kong; Myrtle

2006-09-01

89

MY NASA DATA: Atmospheric Pressure vs. Elevation  

NSDL National Science Digital Library

In this data activity, students use NASA satellite measurements of atmospheric pressure to learn that pressure decreases with height in the atmosphere. Step-by-step instructions for use of the MY NASA DATA Live Access Server (LAS) guide students through selecting a data set, importing the data into a spreadsheet, creating graphs, and analyzing data plots. The lesson provides detailed procedures, related links and sample graphs, follow-up questions, extensions, and teacher notes. Designed for student use, MY NASA DATA LAS samples micro datasets from large scientific data archives, and provides structured investigations engaging students in exploration of remotely-sensed data to answer real world questions.

90

Stability of atmospheric pressure glow discharges  

NASA Astrophysics Data System (ADS)

There has been a considerable interest in non-thermal atmospheric pressure discharges over the past decade due to increased number of industrial applications. Although non-thermal atmospheric pressure discharges have been intensively studied for the past century the clear physical picture of these discharges is far from being complete. Spontaneous transition of non-thermal atmospheric pressure discharges to thermal discharge and discharge filamentation are among least understood plasma phenomena. The discharge stability and reliable control of plasma parameters are highly desirable for numerous applications. This study focuses on stability of atmospheric pressure glow discharges with respect to filamentation and arcing. Atmospheric pressure glow discharge (APG) is the newest and the most promising addition to the family of non-thermal atmospheric pressure discharges. However this discharge is very susceptible to thermal instability which causes arcing, loss of uniformity and significant damage to electrodes. Suppression of thermal instability and effective control of discharge parameters is critical for industrial applications. A model was developed to understand transition to arc in atmospheric pressure glow discharges. APG discharges that operate in pure helium and in helium with addition of oxygen and nitrogen were considered in these studies. Simulation results indicate that arcing is the result of sheath breakdown rather than thermal instability. It was shown that although sheath breakdown is always followed by overheating the transition to arc in atmospheric glow discharges is not a result of thermal instability. In second part of this research interaction between plasma filaments in dielectric barrier discharges has been studied. This interaction is responsible for the formation of microdischarge patterns reminiscent of two-dimensional crystals. Depending on the application, microdischarge patterns may have a significant influence on DBD performance, particularly when spatial uniformity is desired. A microdischarge interaction model is proposed and a Monte-Carlo simulation of microdischarge interactions in the discharge is presented. A new method for analysis of microdischarge patterns that allow measuring the degree of pattern regularity was developed. Simulated and experimental patterns were compared using the newly developed method. Analysis of microdischarge patterns shows that regularity of the patterns increases with the number of excitation cycles used to produce the pattern.

Chirokov, Alexandre V.

91

SIMION ion optics simulations at atmospheric pressure  

Microsoft Academic Search

A method for simulating the motions of charged particles in atmospheric pressure conditions in electrostatic and magnetic fields has been developed and implemented in a user program for SIMION 7.0 and the predictive capability of the model tested against experiment. The statistical diffusion simulation (SDS) user program avoids the computationally intensive issues of high collision rates by employing collision statistics

Anthony D. Appelhans; David A. Dahl

2005-01-01

92

Electrodeless microwave plasma torch at atmospheric pressure  

Microsoft Academic Search

Summary form only given, as follows. Environmental clean-up and energy efficiency enhancement utilize plasma generated from air at the atmospheric pressure. Perfluorocompounds (PFC's), which have long lifetimes and large global warming potentials, are widely used during plasma etching and plasma-assisted chamber cleaning processes in metal and dielectric film chemical vapor deposition (CVD) systems. Electrodes of the arc plasma torches oxidize

J. H. Kim; Y. C. Hong; H. S. Uhm

2002-01-01

93

Targeting the cancer cell cycle by cold atmospheric plasma  

PubMed Central

Cold atmospheric plasma (CAP), a technology based on quasi-neutral ionized gas at low temperatures, is currently being evaluated as a new highly selective alternative addition to existing cancer therapies. Here, we present a first attempt to identify the mechanism of CAP action. CAP induced a robust ~2-fold G2/M increase in two different types of cancer cells with different degrees of tumorigenicity. We hypothesize that the increased sensitivity of cancer cells to CAP treatment is caused by differences in the distribution of cancer cells and normal cells within the cell cycle. The expression of ?H2A.X (pSer139), an oxidative stress reporter indicating S-phase damage, is enhanced specifically within CAP treated cells in the S phase of the cell cycle. Together with a significant decrease in EdU-incorporation after CAP, these data suggest that tumorigenic cancer cells are more susceptible to CAP treatment.

Volotskova, O.; Hawley, T. S.; Stepp, M. A.; Keidar, M.

2012-01-01

94

Partial-pressure measurement of atmospheric-pressure binary gas using two pressure gauges  

Microsoft Academic Search

We investigated a new method to measure the partial pressure of a binary gas system at near-atmospheric pressure conditions. The method utilizes two types of vacuum gauges, a capacitance manometer and a quartz friction pressure gauge. The partial pressure of the binary gas can be estimated by measuring the impedance change with a quartz friction pressure gauge, which depends on

Akira Kurokawa; Kenji Odaka; Shingo Ichimura

2004-01-01

95

The Thermal Pressure Distribution of a Simulated Cold Neutral Medium  

NASA Astrophysics Data System (ADS)

We numerically study the thermal pressure distribution in a gas with thermal properties similar to those of the cold neutral interstellar gas by analyzing three-dimensional hydrodynamic models in boxes with sides of 100 pc with turbulent compressible forcing at 50 pc and different Mach numbers. We find that at high pressures and for large Mach numbers, both the volume-weighted and the density-weighted distributions can be appropriately described by a log-normal distribution, whereas for small Mach numbers they are better described by a power law. Thermal pressure distributions resulting from similar simulations but with self-gravity differ only for low Mach numbers; in this case, they develop a high pressure tail.

Gazol, Adriana

2014-07-01

96

Large area atmospheric-pressure plasma jet  

DOEpatents

Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

Selwyn, Gary S. (Los Alamos, NM); Henins, Ivars (Los Alamos, NM); Babayan, Steve E. (Huntington Beach, CA); Hicks, Robert F. (Los Angeles, CA)

2001-01-01

97

Protein destruction by atmospheric pressure glow discharges  

SciTech Connect

It is well established that atmospheric pressure glow discharges are capable of bacterial inactivation. Much less known is their ability to destruct infectious proteins, even though surgical instruments are often contaminated by both bacteria and proteinaceous matters. In this letter, the authors present a study of protein destruction using a low-temperature atmospheric dielectric-barrier discharge jet. Clear evidences of protein removal are presented with data of several complimentary experiments using scanning electron microscopy, electron dispersive x-ray analysis, electrophoresis, laser-induced fluorescence microscopy, and protein reduction kinetics. Considerable degradation is observed of protein fragments that remain on their substrate surface after plasma treatment.

Deng, X. T.; Shi, J. J.; Chen, H. L.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); MRC Toxicology Unit, University of Leicester, Leicester, Leicestershire LE1 9HN (United Kingdom); Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

2007-01-01

98

Cold Atmospheric Plasma: methods of production and application in dentistry and oncology  

PubMed Central

Cold Atmospheric Plasma is an ionized gas that has recently been extensively studied by researchers as a possible therapy in dentistry and oncology. Several different gases can be used to produce Cold Atmospheric Plasma such as Helium, Argon, Nitrogen, Heliox, and air. There are many methods of production by which cold atmospheric plasma is created. Each unique method can be used in different biomedical areas. In dentistry, researchers have mostly investigated the antimicrobial effects produced by plasma as a means to remove dental biofilms and eradicate oral pathogens. It has been shown that reactive oxidative species, charged particles, and UV photons play the main role. Cold Atmospheric Plasma has also found a minor, but important role in tooth whitening and composite restoration. Furthermore, it has been demonstrated that Cold Atmospheric Plasma induces apoptosis, necrosis, cell detachment, and senescence by disrupting the S phase of cell replication in tumor cells. This unique finding opens up its potential therapy in oncology.

2013-01-01

99

Atmospheric pressure loading displacement of SLR stations  

Microsoft Academic Search

This paper addresses the local displacement at ground stations of the world-wide Satellite Laser Ranging (SLR) network induced by atmospheric pressure variations. Since currently available modelling options do not satisfy the requirements for the target application (real-time availability, complete coverage of SLR network), a new representation is developed. In a first step, the 3-dimensional displacements are computed from a 6-hourly

D. Bock; R. Noomen; H.-G. Scherneck

2005-01-01

100

Circular array of stable atmospheric pressure microplasmas  

NASA Astrophysics Data System (ADS)

A circular array composed of six quarter-wavelength microstripline resonators sustains a stable ring-shaped microplasma in atmospheric pressure argon. A single power source (1 GHz, <5 W) drives all six resonators. The operation of the array is modeled by coupled mode theory (CMT) and confirmed by electromagnetic simulations. Non-uniformities in the plasma ring are attributed to parasitic plasma sheath capacitance and confirmed by CMT.

Wu, C.; Zhang, Z.-B.; Hoskinson, A.; Hopwood, J.

2010-12-01

101

Martian Atmospheric Pressure Static Charge Elimination Tool  

NASA Technical Reports Server (NTRS)

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.

Johansen, Michael R.

2014-01-01

102

Special issue: diagnostics of atmospheric pressure microplasmas  

NASA Astrophysics Data System (ADS)

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, e.g. Werner von Siemens [9], who studied a dielectric barrier discharge (DBD) in the context of ozone generation. DBD discharges often consist of numerous filamentary discharges which are inherently transient in nature and with a characteristic size similar to the dimensions of microplasmas. Several groups are investigating the stabilization of such plasma filaments to perform temporal and spatial resolved diagnostics. To this end and due to the many similar challenges for diagnostics, this type of discharge is also included in this special issue. Research on microplasmas is performed in many groups spread all over the world, and a biannual workshop is devoted to the topic. The 7th edition of this International Workshop on Microplasmas was held in Beijing in May 2013. Large research programs consisting of clusters of research labs such as in Japan, Germany, France and the USA have been producing a wealth of information available in the literature. As the editors of this special issue, we are very pleased to have attracted a collection of excellent papers from leading experts in the field covering most of the current diagnostics performed in microplasmas. As an introduction to the regular special issue papers, a review paper is included [10]. It describes the key characteristics of atmospheric pressure plasmas and microplasmas in particular, and reviews the state of the art in plasma diagnostics. Special attention has been given in this review to highlighting the issues and challenges to probe microplasmas. The regular papers cover a large range of different diagnostics including coherent anti-Stokes Raman scattering (CARS) [11], (two-photon) laser induced fluorescence ((Ta)LIF) [12, 13, 18, 24], absorption spectroscopy [13-18], optical emission spectroscopy [12, 16-21, 24], imaging [22, 23], surface diagnostics [24, 25] and mass spectrometry [26, 27]. Different aspects of microplasmas are broadly investigated from a perspective of diagnostics, modelling and applications. Diagnostics are pivotal to both the development of models and the optimization and explorat

Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

2013-11-01

103

N Reactor pressure tube cold drawing simulation tests  

SciTech Connect

Pressure tubes are required at N Reactor for routine reactor retubing. Because the pressure tube inventory is insufficient for present and future retubing, Westinghouse Hanford Company (WHC) has decided to fabricate tubes at a Hanford facility. During planning, WHC determined that the tube drawing parameters needed verification to enable scoping and specification of the tube manufacturing process. Pacific Northwest Laboratory (PNL) provided development engineering and metal-working services for UNC Nuclear Industries, Inc., now WHC. The main objective of this work was to develop drawing process parameters for N Reactor`s full-sized tubing. The 306W Building 25-ton draw bench was used. The drawing test tubing was sized in proportion to full-sized pressure tube characteristics (strain ratio and cold work) but had dimensions scaled to PNL`s draw bench pull force capability. 6 ref., 28 figs., 20 tabs.

Page, R.E.; Faber, S.M. Jr.; Ruff, E.S.

1988-03-01

104

Integrin activation by a cold atmospheric plasma jet  

NASA Astrophysics Data System (ADS)

Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. In this paper, we explore potential mechanisms by which CAP alters cell migration and influences cell adhesion. We focus on the study of CAP interaction with fibroblasts and corneal epithelial cells. The data show that fibroblasts and corneal epithelial cells have different thresholds (treatment times) required to achieve maximum inhibition of cell migration. Both cell types reduced their migration rates by ˜30-40% after CAP compared to control cells. Also, the impact of CAP treatment on cell migration and persistence of fibroblasts after integrin activation by MnCl2, serum starvation or replating cells onto surfaces coated with integrin ligands is assessed; the results show that activation by MnCl2 or starvation attenuates cells’ responses to plasma. Studies carried out to assess the impact of CAP treatment on the activation state of ?1 integrin and focal adhesion size by using immunofluorescence show that fibroblasts have more active ?1 integrin on their surface and large focal adhesions after CAP treatment. Based on these data, a thermodynamic model is presented to explain how CAP leads to integrin activation and focal adhesion assembly.

Volotskova, Olga; Stepp, Mary Ann; Keidar, Michael

2012-05-01

105

A global mechanism creating low atmospheric luminous cold plasmas  

NASA Astrophysics Data System (ADS)

Red, white/yellow and blue balls of light have been observed in the low atmosphere over the Hessdalen valley , Norway, standing still and moving horizontally with random speed. Characteristics of these transient luminous phenomena in Hessdalen, and data from America, suggest that the process which creates these low atmospheric plasmas is a global mechanism, not only localized to the remote and desolated Hessdalen valley in Norway (62Deg.N - 11Deg.E). Transient luminous phenomena's has been observed in the low atmosphere over the Hessdalen valley for over 200 years. The first written documentation goes back to 1811 when the priest Jakob Tode Krogh wrote about it in his diary. Since 1982, inhabitants, tourists, journalists and scientists have done recurrent observations. E.P.Strand conducted the first scientific campaign in 1984, documenting over 50 observations in one month. 15 years later, Norwegian and Italian scientists installed the first permanent automated research base here. In 2010 French researchers joined this collaboration and installed two additional research bases. This transient luminous phenomenon, TLP, has been detected simultaneously on optical and radar devices, but electromagnetic radiation from this phenomenon has until now eluded detection. Smirnov (1994) and Zou(1994) was among the first scientist who used plasma physics trying to explain this phenomenon. Work done by Pavia & Taft (2010 and 2012) suggests that the TLP in Hessdalen probably is dusty or cold plasma, arranged as a cluster of Coulomb crystals. Optical spectrum data obtained by Strand (1984), Teodorani (2004) and Hauge (2007) showing a continuous optical spectrum support this hypothesis. Pictures of spiraling light rays obtained by Strand in 1984, and Hauge in 2004 and 2010 suggests that this plasma is moving in a strong magnetic field, and might be created by it. Radar reflections from the TLP in Hessdalen obtained by Strand in 1984 and Montebugnoli and Monari in 2007 points towards that the TLP acts as an reflecting surface for electromagnetic waves in the frequencies ranging from 0,4 - 10GHz, which ionized matter, plasma, will do. The non-explained TLP in Hessdalen may therefor be related to the generation of low atmospheric plasma, created by an undetected energy /excitation source. Data obtained from Mexico and USA seems to correlate with the characteristics of the Hessdalen phenomena, suggesting that the mechanism creating the Hessdalen phenomena is global and not only localized to the Hessdalen valley. These data will be shown and analyzed. Hessdalen is known for having a very high frequency of TLP observations yearly, compared to other places in the world. This very active process creating TLPs in Hessdalen may be connected to magnetic pulsations/storms since several optical observations done the last 6 years are coupled to Aurora Borealis outbreaks in the Hessdalen atmosphere. Aurora borealis is often seen on these latitudes, and this may be one of the explanations for the high observation frequency. The Hessdalen region is an old mining district with deep mining-shafts, going down to 1000m of depth, and huge layers of zinc and copper ore. This creates conducting channels for current in the ground and reflecting surfaces for electromagnetic radiation. Examining these physical facts coupled to outbreaks of Aurora borealis may contribute to an better understanding of the mechanisms creating atmospheric plasma in Hessdalen valley and other places in the world.

Gitle Hauge, Bjørn; Petter Strand, Erling

2014-05-01

106

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

The objective of this project is to identify the key physics and chemistry underlying the use of atmospheric pressure plasmas for etching removal of actinides and actinide surrogates. This includes understanding of basic discharge mechanism at atmospheric pressure, gas and surface phase chemistry, and optimization and scale-up effort of atmospheric pressure plasma jet (APPJ).

Hicks, Robert F.; Selwyn, Gary

1999-06-01

107

Fluctuating Pressure Data from 2-D Nozzle Cold Flow Tests (Dual Bell)  

NASA Technical Reports Server (NTRS)

Rocket engines nozzle performance changes as a vehicle climbs through the atmosphere. An altitude compensating nozzle, ACN, is intended to improve on a fixed geometry bell nozzle that performs at optimum at only one trajectory point. In addition to nozzle performance, nozzle transient loads are an important consideration. Any nozzle experiences large transient toads when shocks pass through the nozzle at start and shutdown. Additional transient toads will occur at transitional flow conditions. The objectives of cold flow nozzle testing at MSFC are CFD benchmark / calibration and Unsteady flow / sideloads. Initial testing performed with 2-D inserts to 14" transonic wind tunnel. Recent review of 2-D data in preparation for nozzle test facility 3-D testing. This presentation shows fluctuating pressure data and some observations from 2-D dual-bell nozzle cold flow tests.

Nesman, Tomas E.

2001-01-01

108

Atmospheric Pressure RF Capacitive Plasma Source  

NASA Astrophysics Data System (ADS)

An atmospheric pressure plasma source has been developed and it exhibits many desirable properties for a wide range of plasma applications without the complication and expense of an attached vacuum system. An atmospheric pressure plasma jet (APPJ) operates with rf power and produces a ?-mode capacitive discharge that is stable, steady-state, and non-thermal. The plasma parameters of this source have been measured: electron densities of 10^11 cm-3 and electron temperatures of 2 eV by using neutral bremsstrahlung emission. The gas temperature of less than 150 ^oC is determined in the discharge by using rotational intensity distribution. Localized electron heating near the sheath boundary has been observed and is related to the discharge stability and subsequent ? to ? mode (or arcing) transition. Recent progress has been made to replace the helium in the discharge while maintaining discharge stability and reactivity, thus broadening the appeal of this source. Thus far, the APPJ has been used to etch polyimide, tungsten, tantalum, and silicon dioxide and to deposit silicon dioxide films at rates comparable to those in low pressure plasma sources.

Park, Jaeyoung; Henins, Ivars; Herrmann, Hans W.; Selwyn, Gary S.

2000-10-01

109

Survival of Deep-Sea Shrimp ( Alvinocaris sp.) During Decompression and Larval Hatching at Atmospheric Pressure  

Microsoft Academic Search

We report successful larval hatching of deep-sea shrimp after decompression to atmospheric pressure. Three specimens of deep-sea shrimp were collected from an ocean depth of 1157 m at cold-seep sites off Hatsushima Island in Sagami Bay, Japan, using a pressure-stat aquarium system. Phylogenetic analysis of Alvinocaris sp. based on cytochrome c oxidase subunit gene sequences confirmed that these species were

Sumihiro Koyama; Takahiko Nagahama; Noriyuki Ootsu; Tomoji Takayama; Masae Horii; Satoshi Konishi; Tetsuya Miwa; Yoichi Ishikawa; Masuo Aizawa

2005-01-01

110

The Remarkable High Pressure of the Local Leo Cold Cloud  

NASA Astrophysics Data System (ADS)

Using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope, we have obtained high-resolution ultraviolet spectra of the C I absorption toward two stars behind the Local Leo Cold Cloud (LLCC). At a distance (?20 pc) that places it well inside the Local Bubble, the LLCC is the nearest example of the coldest known (T ? 20 K) diffuse interstellar clouds. The STIS measurements of the C I fine-structure excitation toward HD 85259 and HD 83023 indicate that the thermal gas pressure of the LLCC is much greater than that of the warm clouds in the Local Bubble. The mean LLCC pressure measured toward these two stars (60,000 cm-3 K) implies an H I density of ?3000 cm-3 and a cloud thickness of ?200 AU at the 20 K cloud temperature. Such a thin, cold, dense structure could arise at the collision interface between converging flows of warm gas. However, the measured LLCC pressure is appreciably higher than that expected in the colliding-cloud interpretation given the velocity and column density constraints on warm clouds in the HD 85259 and HD 83023 sightlines. Additional STIS measurements of the Zn II, Ni II, and Cr II column densities toward HD 85259 indicate that the LLCC has a modest "warm cloud" dust depletion pattern consistent with its low dust-to-gas ratio determined from H I 21 cm and 100 ?m observations. In support of the inferred sheet-like geometry for the LLCC, a multi-epoch comparison of the Na I absorption toward a high-proper-motion background star reveals a 40% column density variation indicative of LLCC Na I structure on a scale of ?50 AU.

Meyer, David M.; Lauroesch, J. T.; Peek, J. E. G.; Heiles, Carl

2012-06-01

111

THE REMARKABLE HIGH PRESSURE OF THE LOCAL LEO COLD CLOUD  

SciTech Connect

Using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope, we have obtained high-resolution ultraviolet spectra of the C I absorption toward two stars behind the Local Leo Cold Cloud (LLCC). At a distance ( Almost-Equal-To 20 pc) that places it well inside the Local Bubble, the LLCC is the nearest example of the coldest known (T Almost-Equal-To 20 K) diffuse interstellar clouds. The STIS measurements of the C I fine-structure excitation toward HD 85259 and HD 83023 indicate that the thermal gas pressure of the LLCC is much greater than that of the warm clouds in the Local Bubble. The mean LLCC pressure measured toward these two stars (60,000 cm{sup -3} K) implies an H I density of Almost-Equal-To 3000 cm{sup -3} and a cloud thickness of Almost-Equal-To 200 AU at the 20 K cloud temperature. Such a thin, cold, dense structure could arise at the collision interface between converging flows of warm gas. However, the measured LLCC pressure is appreciably higher than that expected in the colliding-cloud interpretation given the velocity and column density constraints on warm clouds in the HD 85259 and HD 83023 sightlines. Additional STIS measurements of the Zn II, Ni II, and Cr II column densities toward HD 85259 indicate that the LLCC has a modest 'warm cloud' dust depletion pattern consistent with its low dust-to-gas ratio determined from H I 21 cm and 100 {mu}m observations. In support of the inferred sheet-like geometry for the LLCC, a multi-epoch comparison of the Na I absorption toward a high-proper-motion background star reveals a 40% column density variation indicative of LLCC Na I structure on a scale of Almost-Equal-To 50 AU.

Meyer, David M. [Center for Interdisciplinary Exploration and Research in Astrophysics, Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Lauroesch, J. T. [Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292 (United States); Peek, J. E. G. [Department of Astronomy, Columbia University, Pupin Physics Laboratories, 550 West 120th Street, New York, NY 10027 (United States); Heiles, Carl, E-mail: davemeyer@northwestern.edu, E-mail: jtlaur01@louisville.edu, E-mail: goldston@gmail.com, E-mail: heiles@astro.berkeley.edu [Department of Astronomy, University of California, Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States)

2012-06-20

112

Study on an atmospheric pressure glow discharge  

NASA Astrophysics Data System (ADS)

Experiments were performed on an atmospheric pressure glow discharge (APGD) in an air gap between two dielectric barrier electrodes. While it is possible to get an APGD in a 2 mm air gap, it is possible to get only a filament discharge in a 5 mm air gap. The development of an electron avalanche in such a gap was numerically simulated. It was found that the critical applied field for a 5 mm electron avalanche to transit to a streamer is equal to 35.07 kV cm-1. This calculated critical applied field is in good agreement with the experimental one. The experimental and theoretical results confirm that only a filament discharge, rather than a glow discharge, can be produced in an atmospheric pressure air gap that is not less than 5 mm if it is not possible to lower the breakdown field of air. A resistive barrier discharge (RBD) was theoretically analysed and the development of RBD was numerically simulated. If a kilohertz discharge is required, the parameters of the resistive layer should be in the range rhovarepsilonr = (109-1011) Omega cm. APGD in a helium gap was realized using 50 Hz line power with a suitably fabricated resistive layer.

Wang, Xinxin; Li, Chengrong; Lu, Mingze; Pu, Yikang

2003-08-01

113

Chaos in atmospheric-pressure plasma jets  

NASA Astrophysics Data System (ADS)

We report detailed characterization of a low-temperature atmospheric-pressure plasma jet that exhibits regimes of periodic, quasi-periodic and chaotic behaviors. Power spectra, phase portraits, stroboscopic section and bifurcation diagram of the discharge current combine to comprehensively demonstrate the existence of chaos, and this evidence is strengthened with a nonlinear dynamics analysis using two control parameters that maps out periodic, period-multiplication, and chaotic regimes over a wide range of the input voltage and gas flow rate. In addition, optical emission signatures of excited plasma species are used as the second and independent observable to demonstrate the presence of chaos and period-doubling in both the concentrations and composition of plasma species, suggesting a similar array of periodic, quasi-periodic and chaotic regimes in plasma chemistry. The presence of quasi-periodic and chaotic regimes in structurally unbounded low-temperature atmospheric plasmas not only is important as a fundamental scientific topic but also has interesting implications for their numerous applications. Chaos may be undesirable for industrial applications where cycle-to-cycle reproducibility is important, yet for treatment of cell-containing materials including living tissues it may offer a novel route to combat some of the major challenges in medicine such as drug resistance. Chaos in low-temperature atmospheric plasmas and its effective control are likely to open up new vistas for medical technologies.

Walsh, J. L.; Iza, F.; Janson, N. B.; Kong, M. G.

2012-06-01

114

Evaluation of Diagnostic Atmospheric Dispersion Models for 'Cold Spill' Applications at Vandenberg Air Force Base, California.  

National Technical Information Service (NTIS)

Six diagnostic atmospheric dispersion modeling groups: NUATMOS/CITPUFF, CALMET/CALPUFF PGEMS, WOCSS/MACHWIND/Adaptive plume, and LINCOM/RIMPUFF/HEAVYPUFF are evaluated for use in specifying toxic hazard corridors for rocket propellent and oxidizer cold sp...

R. F. Kamada

1992-01-01

115

[Disorders caused by heat, cold, and abnormal pressure].  

PubMed

Exposure to heat disturbs the homeostasis of body water, serum osmosis, and core temperature, resulting in the development of heat cramp, heat syncope, heat exhaustion, and heat stroke. Commonly coexisting risks are humidity, windlessness, infrared radiation, physical exertion, continuous work, chemical protective clothing, and lack of acclimatization. Exposure to cold constricts peripheral arteries and reduces metabolism, resulting in the development of chilblains, frostbite, immersion foot, and hypothermia. Wind, water immersion, and alcohol drinking will aggravate the symptoms. Exposure to abnormal pressure underwater or inside caissons or air cabins compresses or distends closed cavities inside the body, resulting in squeeze, nitrogen narcosis, oxygen intoxication, decompression sickness, reverse block, lung edema, and arterial gas embolism. Multifaceted preventive measures and on-site emergency care should be undertaken. PMID:24605519

Horie, Seichi

2014-02-01

116

Cold atmospheric plasma sterilization: from bacteria to biomolecules  

NASA Astrophysics Data System (ADS)

Although ionized gases have been known to have biological effects for more than 100 years, their impact on the practice in healthcare service became very significant only recently. Today, plasma-based surgical tools are used for tissue reduction and blood coagulation as surgical procedures. Most significant however is the speed at which low-temperature gas plasmas are finding new applications in medicine and biology, including plasma sterilization, wound healing, and cancer therapies just to name a few. In the terminology of biotechnology, the ``pipeline'' is long and exciting. This presentation reviews the current status of the field with a particular emphasis on plasma inactivation of microorganisms and biomolecules, for which comprehensive scientific evidence has been obtained. Some of the early speculations of biocidal plasma species are now being confirmed through a combination of optical emission spectroscopy, laser-induced fluorescence, mass spectrometry, fluid simulation and biological sensing with mutated bacteria. Similarly, fundamental studies are being performed to examine cell components targeted by gas plasmas, from membrane, through lipid and membrane proteins, to DNA. Scientific challenge is significant, as the usual complexity of plasma dynamics and plasma chemistry is compounded by the added complication that cells are live and constantly evolving. Nevertheless, the current understanding of plasma inactivation currently provides strong momentum for plasma decontamination technologies to be realized in healthcare. We will discuss the issue of protein and tissue contaminations of surgical instruments and how cold atmospheric plasmas may be used to degrade and reduce their surface load. In the context of plasma interaction with biomolecules, we will consider recent data of plasma degradation of adhesion proteins of melanoma cells. These adhesion proteins are important for cancer cell migration and spread. If low-temperature plasmas could be used to degrade them, it could form a control strategy for cancer spread. This adds to the option of plasma-triggered programmed cell death (apoptosis). Whilst opportunities thus highlighted are significant and exciting, the underpinning science poses many open questions. The presentation will then discuss main requirements for plasma sources appropriate for their biomedical applications, in terms of the scope of up-scaling, the ability to treat uneven surfaces of varying materials, the range of plasma chemistry, and the control of plasma instabilities. Finally a perspective will be offered, in terms of both opportunities and challenges.

Kong, Michael

2009-10-01

117

Survival of deep-sea shrimp (Alvinocaris sp.) during decompression and larval hatching at atmospheric pressure.  

PubMed

We report successful larval hatching of deep-sea shrimp after decompression to atmospheric pressure. Three specimens of deep-sea shrimp were collected from an ocean depth of 1157 m at cold-seep sites off Hatsushima Island in Sagami Bay, Japan, using a pressure-stat aquarium system. Phylogenetic analysis of Alvinocaris sp. based on cytochrome c oxidase subunit gene sequences confirmed that these species were a member of the genus Alvinocaris. All 3 specimens survived to reach atmospheric pressure conditions after stepwise 63-day decompression. Two of the specimens contained eggs, which hatched after 10 and 16 days, respectively, of full decompression. Although no molting of the shrimp larvae was observed during 74 days of rearing under atmospheric pressure, the larvae developed conventional dark-adapted eyes after 15 days. PMID:15942807

Koyama, Sumihiro; Nagahama, Takahiko; Ootsu, Noriyuki; Takayama, Tomoji; Horii, Masae; Konishi, Satoshi; Miwa, Tetsuya; Ishikawa, Yoichi; Aizawa, Masuo

2005-01-01

118

Atmospheric pressure loading effects on Global Positioning System coordinate determinations  

Microsoft Academic Search

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

Tonie M. vanDam; Geoffrey Blewitt; Michael B. Heflin

1994-01-01

119

Propagation of an atmospheric pressure plasma plume  

SciTech Connect

The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2009-02-15

120

Preparation of Cold Brew Tea by Explosion Puffing Drying at Variable Temperature and Pressure  

Microsoft Academic Search

Cold brew tea was prepared using explosion puffing drying at variable temperature and pressure. The influences of moisture content of predried tea leaves, freezing pretreatment times at ?18°C, and puffing temperature on water extracts content of cold brew tea were studied according to the orthogonal experiments of processing of cold brew tea based on single factors. The biochemistry ingredients of

Xin-Yi He; Jin-Fu Liu; Zong-Hai Huang

2011-01-01

121

Physical Mechanisms of Inactivation of Bacillus subtilis Spores Using Cold Atmospheric Plasmas  

Microsoft Academic Search

This paper presents a detailed study of the potential physical mechanisms of the microbial inactivation by cold atmospheric plasmas. With the Bacillus subtilis spores as a model microorganism and an atmospheric-plasma plume in helium flow, optical emission spectroscopy and inactivation kinetics are used to demonstrate the dominating role played by the reactive oxygen species (e.g., atomic oxygen and OH) as

Xutao Deng; Jianjun Shi; Michael G. Kong

2006-01-01

122

Effect of the atmospheric pressure nonequilibrium plasmas on the conformational changes of plasmid DNA  

NASA Astrophysics Data System (ADS)

The cold atmospheric pressure plasma, which has been widely used for biomedical applications, may potentially affect the conformation of DNA. In this letter, an atmospheric pressure plasma plume is used to investigate its effects on the conformational changes of DNA of plasmid pAHC25. It is found that the plasma plume could cause plasmid DNA topology alteration, resulting in the percentage of the supercoiled plasmid DNA form decreased while that of the open circular and linearized form of plasmid DNA increased as detected by agrose gel electrophoresis. On the other hand, further investigation by using polymerase chain reaction method shows that the atmospheric pressure plasma jet treatments under proper conditions does not affect the genes of the plasmid DNA, which may have potential application in increasing the transformation frequency by genetic engineering.

Yan, Xu; Zou, Fei; Lu, Xin Pei; He, Guangyuan; Shi, Meng Jun; Xiong, Qing; Gao, Xuan; Xiong, Zilan; Li, Yin; Ma, Feng Yun; Yu, Men; Wang, Chang Dong; Wang, Yuesheng; Yang, Guangxiao

2009-08-01

123

Effect of the atmospheric pressure nonequilibrium plasmas on the conformational changes of plasmid DNA  

SciTech Connect

The cold atmospheric pressure plasma, which has been widely used for biomedical applications, may potentially affect the conformation of DNA. In this letter, an atmospheric pressure plasma plume is used to investigate its effects on the conformational changes of DNA of plasmid pAHC25. It is found that the plasma plume could cause plasmid DNA topology alteration, resulting in the percentage of the supercoiled plasmid DNA form decreased while that of the open circular and linearized form of plasmid DNA increased as detected by agrose gel electrophoresis. On the other hand, further investigation by using polymerase chain reaction method shows that the atmospheric pressure plasma jet treatments under proper conditions does not affect the genes of the plasmid DNA, which may have potential application in increasing the transformation frequency by genetic engineering.

Yan Xu; He Guangyuan; Shi Mengjun; Gao Xuan; Li Yin; Ma Fengyun; Yu Men; Wang Changdong; Wang Yuesheng; Yang Guangxiao [Genetic Engineering International Cooperation Base of Ministry of Science and Technology, Key Laboratory of Molecular Biophysics of Ministry of Education, China-UK HUST-RRes Genetic Engineering and Genomics Joint Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan 430074 (China); Zou Fei; Lu Xinpei; Xiong Qing; Xiong Zilan [College of Electrical and Electronics Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2009-08-24

124

Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua.  

PubMed

Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC voltage, excitation frequency and the presence of oxygen in the carrier gas resulted in the greatest inactivation efficiency, and this was confirmed with further studies on chicken muscle and skin. Under optimal conditions, a 10 s treatment gave > 3 log reductions of L. innocua on membrane filters, an 8 min treatment gave 1 log reduction on skin, and a 4 min treatment gave > 3 log reductions on muscle. These results show that the efficacy of gas plasma treatment is greatly affected by surface topography. Scanning electron microscopy (SEM) images of chicken muscle and skin revealed surface features wherein bacteria could effectively be protected from the chemical species generated within the gas plasma. The developments in gas plasma technology necessary for its commercial application to foods are discussed. PMID:21839378

Noriega, Estefanía; Shama, Gilbert; Laca, Adriana; Díaz, Mario; Kong, Michael G

2011-10-01

125

Tooth bleaching with nonthermal atmospheric pressure plasma.  

PubMed

We demonstrated that room temperature plasma could be used for tooth bleaching. A nonthermal, atmospheric pressure, helium plasma jet device was developed to enhance the tooth bleaching effect of hydrogen peroxide (H(2)O(2)). All teeth were sectioned sagittally into halves, which were assigned randomly to either the experimental group or the control group. The experimental group was treated with H(2)O(2) (28%, 20 microL every 30 seconds) plus plasma (5 W) for 10 minutes; the control group was treated with H(2)O(2) alone for the same duration. Removal of the tooth surface protein was demonstrated by scanning electron microscopy images and Ponceau staining. Production of hydroxyl radicals (.OH) was measured by using electron spin resonance spin-trapping. Combining plasma and H(2)O(2) improved the bleaching efficacy by a factor of 3 compared with using H(2)O(2) alone. Tooth surface proteins were noticeably removed by plasma treatment. When a piece of tooth was added to a solution of H(2)O(2) as a catalyst, production of *OH after plasma treatment was 1.9 times greater than when using H(2)O(2) alone. We suggest that the improvement in tooth bleaching induced by plasma is due to the removal of tooth surface proteins and to increased *OH production. PMID:19345811

Lee, Hyun Woo; Kim, Gon Jun; Kim, Jae Moon; Park, Jeong Kil; Lee, Jae Koo; Kim, Gyoo Cheon

2009-04-01

126

RF generated atmospheric pressure plasmas and applications  

NASA Astrophysics Data System (ADS)

RF generated atmospheric pressure plasma sources have been developed for various materials applications. They operate with rf power and produce a ?-mode capacitive discharge that is stable, steady-state, non-thermal, and volumetric. The plasma parameters of this source have been measured: electron densities of 10^11 cm-3 and electron temperatures of 2 eV by using neutral bremsstrahlung emission. Localized electron heating near the sheath boundary has been observed and is related to the discharge stability and ? to ? mode (or arcing) transition using 1D fluid model. The discharge stability improves with increase in rf frequency. The electrode surface property such as the secondary electron emission coefficient also plays a significant role in determining ? to ? mode transition. For example, a stable ?-mode air discharge is produced using 100 MHz rf power with the use of a boron nitride cover on one of the electrodes. In comparison, an air discharge becomes unstable at a lower rf frequency (e.g. 13.56 MHz) or with an alumina cover. Similar results were obtained with various feedgas such as steam, CO_2, and hydrocarbon containing gases. Further characterization of this high frequency source is under progress. For its applications, we have successfully demonstrated the effective neutralization of actual chemical warfare agents such as VX, GD and HD. In addition, significant progresses have been made in the area of etching of organic and metal film etching, and production of novel materials.

Park, Jaeyoung; Herrmann, Hans W.; Henins, Ivars; Gautier, Donald C.

2001-10-01

127

Tilts in the earth's surface caused by atmospheric pressure variations  

Microsoft Academic Search

The drift detected by tide-recording tiltmeters is thought to result from nonperiodic atmospheric pressure and temperature variations which produce elastic deformations that are transmitted downwards from the surface. These deformations can be detected in distant areas of the earth's surface. Examples are presented which show good correlation between the drift detected by tiltmeters and daily atmospheric pressure variations. A lag

K. Z. Kartvelishvili; V. I. Mirianashvili

1977-01-01

128

Mass analysis of an atmospheric pressure plasma needle discharge  

Microsoft Academic Search

Mass spectrometric measurements of a plasma needle (an example of atmospheric pressure non-equilibrium plasma source) were made for neutrals and ions. The measurements were performed for the same geometry as the standard plasma needles albeit for a somewhat increased gas flow. We discuss some of the problems of performing mass analysis at atmospheric pressures. The yields of N, O and

G. Malovic; N. Puac; S. Lazovic; Z. Petrovic

2010-01-01

129

Plasma decontamination at atmospheric pressure - basics and applications  

Microsoft Academic Search

Plasma sources, driven at atmospheric pressure gain more and more interest due to the technological advantages (avoidance of vacuum devices and batch processing). Especially nonthermal plasmas at atmospheric pressure for the antimicrobial treatment of heat sensitive materials are of rapidly growing interest. However, the realisation of industrial plasma-based decontamination or sterilisation technology remains a great challenge. This is due to

K.-D. Weltmann; R. Brandenburg; J. Ehlbeck; R. Foest; E. Kindel; M. Stieber; T. von Woedtke

2008-01-01

130

Stimulation of wound healing by helium atmospheric pressure plasma treatment  

Microsoft Academic Search

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

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

2011-01-01

131

Characterization of a Ferroelectric Atmospheric Pressure Plasma Source  

Microsoft Academic Search

A ferroelectric atmospheric pressure plasma source has been characterized. An RF electric field, with a frequency between 190 and 250 kHz, is employed to create plasma on the surface of a ferroelectric disk at atmospheric pressure. Average power consumption was measured, and images of plasma formation during an RF cycle have been collected. Excited neutrals from the ferroelectric and electrode,

Dustin L. Sullivan; Mark A. Kemp; Scott D. Kovaleski

2007-01-01

132

Decomposition of tetrafluoromethane by water plasma generated under atmospheric pressure  

Microsoft Academic Search

Tetrafluoromethane (CF4) decomposition by water plasma generated under atmospheric pressure was investigated by means of thermodynamic analyses and experiments. Thermodynamic equilibrium calculations were performed between 300 and 6000K at atmospheric pressure. Experimental results indicated that CF4 was completely decomposed by water plasma, and recovery of fluorine can be achieved more than 99%. Influence of factors such as arc current and

Narengerile; Hironori Saito; Takayuki Watanabe

2009-01-01

133

The effect of atmospheric pressure on ventricular assist device output.  

PubMed

The effect of cabin pressure change on the respiratory system during flight is well documented in the literature, but how the change in atmospheric pressure affects ventricular assist device (VAD) output flow has not been studied yet. The purpose of our study was to evaluate the change in VAD output using a mock circulatory system in a low-pressure chamber mimicking high altitude. Changes in output and driving pressure were measured during decompression from 1.0 to 0.7 atm and pressurization from 0.7 to 1.0 atm. Two driving systems were evaluated: the VCT system and the Mobart system. In the VCT system, output and driving pressure remained the same during decompression and pressurization. In the Mobart system, the output decreased as the atmospheric pressure dropped and recovered during pressurization. The lowest output was observed at 0.7 atm, which was 80% of the baseline driven by the Mobart system. Under a practical cabin pressure of 0.8 atm, the output driven by the Mobart system was 90% of the baseline. In the Mobart system, the output decreased as the atmospheric pressure dropped, and recovered during pressurization. However, the decrease in output was slight. In an environment where the atmospheric pressure changes, it is necessary to monitor the diaphragmatic motion of the blood pump and the driving air pressure, and to adjust the systolic:diastolic ratio as well as the positive and negative pressures in a VAD system. PMID:21915797

Goto, Takeshi; Sato, Masaharu; Yamazaki, Akio; Fukuda, Wakako; Watanabe, Ken-Ichi; Daitoku, Kazuyuki; Minakawa, Masahito; Fukui, Kozo; Suzuki, Yasuyuki; Fukuda, Ikuo

2012-03-01

134

Atmospheric Boundary Layer Simulations During Cold Air Outbreaks over the Gulf Stream  

NASA Astrophysics Data System (ADS)

Several large domain 10 and 2 km nested simulations of cold air outbreaks (CAOs) were performed using the Weather Research and Forecast Model (WRF) Advanced Research WRF version 3.2.1. CAOs over the Gulf Stream cause large upward heat and moisture fluxes from the ocean surface to the atmospheric boundary layer. As ocean water density depends on both temperature and salinity, these weather events may have a large impact on the ocean climatology as the Gulf Stream makes its way northward. Specifically, cold air outbreaks act to increase ocean surface density by decreasing the sea surface temperature and increasing the sea surface salinity. Thus, this study quantifies the ocean to atmosphere heat and moisture losses during several cold air outbreaks to better understand the ocean-atmosphere heat transfer.

Walsh, J. E.; Strey, S. T.

2013-12-01

135

Effect of gas pressure on Al coatings by cold gas dynamic spray  

Microsoft Academic Search

Al coatings by cold gas dynamic spray (CGDS, or Cold Spray) technique with pressure condition were investigated. The relatively soft Al has been coated at low gas pressure condition (0.7 MPa) with severe plastic deformation. However, the Al particles in the coatings coated at the higher pressure conditions (1.5 MPa, 2.5 MPa) were not severely deformed. In the case of hardness, the coating

H. Lee; H. Shin; S. Lee; K. Ko

2008-01-01

136

Spectroscopic Characterization of Atmospheric Pressure Glow Plasma  

NASA Astrophysics Data System (ADS)

The thermal structure of methane-fed dielectric barrier discharge (DBD) and atmospheric pressure glow discharge (APG) has been investigated in terms of time-averaged gas temperature profile between two parallel-plate electrodes separated by 1.0 mm. Emission spectroscopy of rotational band of CH ((0,0) 431 nm) was performed for this purpose. DBD and APG was activated by 10 kHz with 2% duty cycle pulsed voltage in order to minimize average gas temperature increase. In DBD, temperature increase of a single microdischarge, on a time average, reached 200 K. It suddenly decreased below 100 K associated with the dark space formation near dielectric barrier. Also, gas temperature in the surface discharge was fairly low because emission in these regions was limited within the initial stages of propagation, whereas energy deposition would continue until microdischarge extinction; Rotational temperature seemed to estimate far below the actual gas temperature in these regions. In APG, gas temperature was uniformly increased by positive column formation. In addition, remarkable temperature increase due to negative glow formation was obtained only near the metallic electrode. In the practical interest, we also investigated net temperature increase with high frequency operations (AC 80 kHz), which depends on not only plasma properties, but also various engineering factors such as flow field, external cooling conditions, and total input power. In DBD, gas temperature in the middle of gas gap was significantly increased with input power due to poor cooling conditions. In APG, on the contrary, gas temperature near electrodes was significantly increased associated with negative glow formation.

Okazaki, Ken

2002-10-01

137

Quality characteristics of the radish grown under reduced atmospheric pressure  

Microsoft Academic Search

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 96kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12kPa,

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

2008-01-01

138

Atmospheric Pressure Plasmas for Decontamination of Complex Medical Devices  

NASA Astrophysics Data System (ADS)

Atmospheric pressure plasma sources produce a multiplicity of different antimicrobial agents and are applicable to even complicated geometries as well as to heat sensitive materials. Thus, atmospheric pressure plasmas have a huge potential for the decontamination of even complex medical devices like central venous catheters and endoscopes. In this paper we present practicable realizations of atmospheric pressure plasma sources, namely plasma jet, dielectric barrier discharge and microwave driven discharge that are able to penetrate fine lumen or are adaptable to difficult geometries. Furthermore, the antimicrobial efficacy of these sources is given for one example setup in each case.

Weltmann, Klaus-Dieter; Winter, Jörn; Polak, Martin; Ehlbeck, Jörg; von Woedtke, Thomas

139

Reduction of surface gravity data from global atmospheric pressure loading  

NASA Astrophysics Data System (ADS)

Besides solid Earth and ocean tides, atmospheric pressure variations are one of the major sources of surface gravity perturbations. As shown by previous studies (Merriam 1992; Mukai et al. 1995; Boy et al. 1998), the usual pressure correction with the help of local pressure measurements and the barometric admittance (a simple transfer function between pressure and gravity, both measured locally) does not allow an adequate estimation of global atmospheric loading. We express the response of the Earth to pressure forcing using a Green's function formalism (Farrell 1972). The atmosphere acts on surface gravity through two effects: first, a direct gravitational attraction by air masses which is sensitive to regional (about 1000 km around the gravimeter) pressure variations; second, an elastic process induced by the Earth's surface deformation and mass redistribution which is sensitive to large scale pressure variations (wavelengths greater than 4000 km). We estimate atmospheric loading using Green's functions and global pressure charts provided by meteorological centres. We introduce different hypotheses on the atmospheric thickness and atmospheric density variations with altitude for the modelling of the direct Newtonian attraction. All computations are compared to gravity data provided by superconducting gravimeters of the GGP (Global Geodynamics Project) network. We show the improvement by modelling global pressure versus the local estimates in terms of reduction of the variance of gravity residuals. We can also validate the inverted barometer (IB) hypothesis as the oceanic response to pressure forcing for periods exceeding one week. The non-inverted barometer (NIB) hypothesis is shown to be definitely an inadequate assumption for describing the oceanic response to atmospheric pressure at seasonal timescales.

Boy, Jean-Paul; Gegout, Pascal; Hinderer, Jacques

2002-05-01

140

Cold Atmospheric Plasma: Charged Species and Their Interactions With Cells and Tissues  

Microsoft Academic Search

Cold atmospheric plasma (CAP) treatment of living tissues becomes a popular topic in modern plasma physics and in medical sciences. The plasma is capable of bacterial inactivation and noninflammatory tissue modification, which makes it an attractive tool for wound healing and the treatment of skin diseases and dental caries. There are still many open issues with regard to the mechanisms

Eva Stoffels; Yukinori Sakiyama; David B. Graves

2008-01-01

141

Cold Atmospheric Plasma for Selectively Ablating Metastatic Breast Cancer Cells  

PubMed Central

Traditional breast cancer treatments such as surgery and radiotherapy contain many inherent limitations with regards to incomplete and nonselective tumor ablation. Cold atomospheric plasma (CAP) is an ionized gas where the ion temperature is close to room temperature. It contains electrons, charged particles, radicals, various excited molecules, UV photons and transient electric fields. These various compositional elements have the potential to either enhance and promote cellular activity, or disrupt and destroy them. In particular, based on this unique composition, CAP could offer a minimally-invasive surgical approach allowing for specific cancer cell or tumor tissue removal without influencing healthy cells. Thus, the objective of this research is to investigate a novel CAP-based therapy for selectively bone metastatic breast cancer treatment. For this purpose, human metastatic breast cancer (BrCa) cells and bone marrow derived human mesenchymal stem cells (MSCs) were separately treated with CAP, and behavioral changes were evaluated after 1, 3, and 5 days of culture. With different treatment times, different BrCa and MSC cell responses were observed. Our results showed that BrCa cells were more sensitive to these CAP treatments than MSCs under plasma dose conditions tested. It demonstrated that CAP can selectively ablate metastatic BrCa cells in vitro without damaging healthy MSCs at the metastatic bone site. In addition, our study showed that CAP treatment can significantly inhibit the migration and invasion of BrCa cells. The results suggest the great potential of CAP for breast cancer therapy.

Wang, Mian; Holmes, Benjamin; Cheng, Xiaoqian; Zhu, Wei; Keidar, Michael; Zhang, Lijie Grace

2013-01-01

142

Electrode Erosion in Arc Discharges at Atmospheric Pressure.  

National Technical Information Service (NTIS)

An experimental investigation was performed in an effort to measure and increase lifetime of electrodes in an arcjet thruster. The electrode erosion of various anode and cathode materials was measured after tests in an atmospheric pressure nitrogen arc di...

T. L. Hardy

1985-01-01

143

Atmospheric-Pressure Plasma Cleaning of Contaiminated Surfaces.  

National Technical Information Service (NTIS)

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of radioactive waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is ...

R. F. Hicks H. W. Herrmann

2004-01-01

144

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces.  

National Technical Information Service (NTIS)

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of heavy metal waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is ...

R. F. Hicks H. W. Hermann

2004-01-01

145

Atmospheric pressure ionisation multiple mass spectrometric analysis of pesticides  

Microsoft Academic Search

Liquid chromatography–multiple mass spectrometry (LC–MSn) has been investigated for analysis of polar pesticides in water using an ion-trap instrument and atmospheric pressure ionisation. Carbamate, triazine and phenylurea pesticides were best ionised as positive ions with atmospheric pressure chemical ionisation, while phenoxy acid herbicides, nitrophenols and bentazone yielded stronger signals as negative ions with pneumatically assisted electrospray. The ion fragmentation processes

Daniela Baglio; Dimitrios Kotzias; Bo Richter Larsen

1999-01-01

146

Laboratory experiments of Titan tholin formed in cold plasma at various pressures: implications for nitrogen-containing polycyclic aromatic compounds in Titan haze  

Microsoft Academic Search

Titan, the largest satellite of Saturn, has a thick nitrogen\\/methane atmosphere with a thick global organic haze. A laboratory analogue of Titan's haze, called tholin, was formed in an inductively coupled plasma from nitrogen\\/methane=90\\/10 gas mixture at various pressures ranging from 13 to 2300 Pa. Chemical and optical properties of the resulting tholin depend on the deposition pressure in cold

Hiroshi Imanaka; Bishun N. Khare; Jamie E. Elsila; Emma L. O. Bakes; Christopher P. McKay; Dale P. Cruikshank; Seiji Sugita; Takafumi Matsui; Richard N. Zare

2004-01-01

147

Measuring Viscosities of Gases at Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

1987-01-01

148

Atmospheric pressure sample inlet for mass spectrometers  

NASA Astrophysics Data System (ADS)

An inlet for a mass spectrometer has been developed for direct sampling of gases over a wide range of pressure (1-760 Torr). The sample inlet is composed of two small orifices that form a pressure reduction region. These orifices are used to limit the flow of sample gas into the mass spectrometer. The pressure inside the pressure reduction region is regulated by a needle valve and a vacuum pump. The flow of gas through the orifices is viscous. The inlet is made of stainless steel and operated at high temperature to prevent surface adsorption and corrosion. Its adaptability to a wide range of pressures is very useful for monitoring process gases during manufacturing processes of microelectronic devices. This inlet can be used for effluent gas analysis at 760 Torr as well as for in situ monitoring of the semiconductor equipment at pressures less than 5 Torr. The inlet provides a fast response to changes in the constituents of gas samples without memory effects. The sample inlet has been tested extensively in the laboratory as well as in field environments.

Dheandhanoo, Seksan; Ciotti, Ralph J.; Ketkar, Suhas N.

2000-12-01

149

Einstein's Tea Leaves and Pressure Systems in the Atmosphere  

ERIC Educational Resources Information Center

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

Tandon, Amit; Marshall, John

2010-01-01

150

Novel applications of atmospheric pressure plasma on textile materials  

NASA Astrophysics Data System (ADS)

Various applications of atmospheric pressure plasma are investigated in conjunction with polymeric materials including paper, polypropylene non-woven fabric, and cotton. The effect of plasma on bulk and surface properties is examined by treating both cellulosic pulp and prefabricated paper with various plasma-gas compositions. After treatment, pulp is processed into paper and the properties are compared. The method of pulp preparation is found to be more significant than the plasma, but differences in density, strength, and surface roughness are apparent for the pulp vs. paper plasma treatments. The plasma is also used to remove sizes of PVA and starch from poly/cotton and cotton fabric respectively. In both cases plasma successfully removes a significant amount of size, but complete size removal is not achieved. Subsequent washes (PVA) or scouring (cotton) to remove the size are less successful than a control, suggesting the plasma is crosslinking the size that is not etched away. However, at short durations in cold water using an oxygen plasma, slightly more PVA is removed than with a control. For the starch sized samples, plasma and scouring are never as successful at removing starch as a conventional enzyme, but plasma improves dyeability without need for scouring. Plasma is also used to graft chemicals to the surface of polypropylene and cotton fabric. HTCC, an antimicrobial is grafted to polypropylene with successful grafting indicated by x-ray photoemission spectroscopy (XPS), dye tests, and Fourier transform infrared spectroscopy (FTIR). Antimicrobial activity of the grafted samples is also characterized. 3ATAC, a vinyl monomer is also grafted to polypropylene and to cotton. Additives including Mohr's salt, potassium persulfate, and diacrylate are assessed to increase yield. Successful grafting of 3ATAC is confirmed by XPS and dye testing. A combination of all three additives is identified as optimum for maximizing graft yield.

Cornelius, Carrie Elizabeth

151

Atmospheric-pressure air microplasma jets in aqueous media for the inactivation of Pseudomonas fluorescens cells  

NASA Astrophysics Data System (ADS)

The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

Zhang, Xianhui; Liu, Dongping; Song, Ying; Sun, Yue; Yang, Si-ze

2013-05-01

152

Atmospheric-pressure air microplasma jets in aqueous media for the inactivation of Pseudomonas fluorescens cells  

SciTech Connect

The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

Zhang, Xianhui; Yang, Si-ze [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China)] [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Dongping [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China) [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China) [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Sun, Yue [School of Physics, Changchun University of Science and Technology, Changchun 130022 (China)] [School of Physics, Changchun University of Science and Technology, Changchun 130022 (China)

2013-05-15

153

3D mixing in hot Jupiters atmospheres. I. Application to the day/night cold trap in HD 209458b  

NASA Astrophysics Data System (ADS)

Context. Hot Jupiters exhibit atmospheric temperatures ranging from hundreds to thousands of Kelvin. Because of their large day-night temperature differences, condensable species that are stable in the gas phase on the dayside - such as TiO and silicates - may condense and gravitationally settle on the nightside. Atmospheric circulation may counterbalance this tendency to gravitationally settle. This three-dimensional (3D) mixing of condensable species has not previously been studied for hot Jupiters, yet it is crucial to assess the existence and distribution of TiO and silicates in the atmospheres of these planets. Aims: We investigate the strength of the nightside cold trap in hot Jupiters atmospheres by investigating the mechanisms and strength of the vertical mixing in these stably stratified atmospheres. We apply our model to the particular case of TiO to address the question of whether TiO can exist at low pressure in sufficient abundances to produce stratospheric thermal inversions despite the nightside cold trap. Methods: We modeled the 3D circulation of HD 209458b including passive (i.e. radiatively inactive) tracers that advect with the 3D flow, with a source and sink term on the nightside to represent their condensation into haze particles and their gravitational settling. Results: We show that global advection patterns produce strong vertical mixing that can keep condensable species aloft as long as they are trapped in particles of sizes of a few microns or less on the nightside. We show that vertical mixing results not from small-scale convection but from the large-scale circulation driven by the day-night heating contrast. Although this vertical mixing is not diffusive in any rigorous sense, a comparison of our results with idealized diffusion models allows a rough estimate of the effective vertical eddy diffusivities in these atmospheres. The parametrization Kzz=5 × 104/ Pbar m2s-1, valid from ~1 bar to a few ?bar, can be used in 1D models of HD 209458b. Moreover, our models exhibit strong spatial and temporal variability in the tracer concentration that could result in observable variations during either transit or secondary eclipse measurements. Finally, we apply our model to the case of TiO in HD 209458b and show that the day-night cold trap would deplete TiO if it condenses into particles bigger than a few microns on the planet's nightside, keeping it from creating the observed stratosphere of the planet. Appendix A is available in electronic form at http://www.aanda.org

Parmentier, Vivien; Showman, Adam P.; Lian, Yuan

2013-10-01

154

Effect of Phase Pressure on Casting Properties in Cold Chamber Die Casting Process  

NASA Astrophysics Data System (ADS)

This paper focuses on the parametric optimization of process parameter in cold chamber die casting for an industrial component (crank case). Three controllable factors of the cold chamber die casting process (namely: 1st phase pressure, 2nd phase pressure and limit switch position) were studied at three levels each by Taguchi's parametric approach and single-response optimization was conducted to identify the main factor controlling surface hardness, weight of casting and dimensional accuracy (?d). Castings were produced using aluminium alloy at recommended parameters through cold chamber die casting process. Analysis shows that in cold chamber die casting process the percentage contribution of 1st phase pressure, limit switch position and 2nd phase pressure for surface hardness is 84.17, 11.43 and 1.93 % respectively. While in the case of weight of cast component, the contribution of limit switch position is 52.26 %, followed by 1st phase pressure and 2nd phase pressure 34.77 and 9.65 % respectively. Further for ?d, contribution of 1st phase pressure is 64.55 %, limit switch position 27.71 % and 2nd phase pressure contributes 4.87 %.

Singh, R.; Kapoor, R.

2013-04-01

155

Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere - Part 2: 3-D modeling of episodic atmospheric transport  

NASA Astrophysics Data System (ADS)

Two 3-dimensional global atmospheric transport models for persistent organic pollutants (POPs) have been employed to investigate the association between the large-scale atmospheric motions and poleward transports of persistent semi-volatile organic chemicals (SVOCs). We examine the modeled daily air concentration of ?- and ?-hexachlorocyclohexane (HCH) over a period from 1997 through 1999 during which a number of episodic atmospheric transport events were detected in this modeling study. These events provide modeling evidence for improving the interpretation on the cold condensation effect and poleward atmospheric transport of SVOCs in the mid-troposphere. Two episodic transport events of ?-HCH (lindane) to the high Arctic (80-90° N), one from Asian and another from Eurasian sources, are reported in this paper. Both events suggest that the episodic atmospheric transports occurring in the mid-troposphere (e.g. from 3000 m to 5500 m height) are driven by atmospheric horizontal and vertical motions. The association of the transport events with atmospheric circulation is briefly discussed. Strong southerly winds, forced by the evolution of two semi-permanent high pressure systems over mid-high latitudes in the Northern Hemisphere, play an important role in the long-range transport (LRT) of HCHs to the high latitudes from its sources. Being consistent with the cold condensation effect and poleward atmospheric transport in a mean meridional atmospheric circulation simulated by a 2-D atmospheric transport model, as reported by the first part of this study, this modeling study indicates that cold condensation is likely occurring more intensively in the mid-troposphere where rapid declining air temperature results in condensed phase of the chemical over and near its source regions and where stronger winds convey the chemical more rapidly to the polar region during the episodic poleward atmospheric transport events.

Zhang, L.; Ma, J.; Tian, C.; Li, Y.; Hung, H.

2010-08-01

156

Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation at the mid-troposphere - Part 2: 3-D modeling of episodic atmospheric transport  

NASA Astrophysics Data System (ADS)

Two 3-dimensional global atmospheric transport models for persistent organic pollutants (POPs) have been employed to investigate the association between the large-scale atmospheric motions and poleward transports of persistent semi-volatile organic chemicals (SVOCs). We examine the modeled daily air concentration of ?- and ?-hexachlorocyclohexane (HCH) over a period from 1997-1999 during which a number of episodic atmospheric transport events were detected in this modeling study. These events provide modeling evidence for improving the interpretation on the cold condensation effect and poleward atmospheric transport of SVOCs at the mid-troposphere. Two episodic transport events of ?-HCH (lindane) to the high Arctic (80-90° N), one from Asian and another from Eurasian sources, are reported in this paper. The both events suggest that the episodic atmospheric transports occurring at the mid-troposphere (e.g. from 3000-5500 m height) are driven by atmospheric horizontal and vertical motions. The association of the transport events with atmospheric circulation is briefly discussed. Strong southerly winds, forced by the evolution of two semi-permanent high pressure systems over mid-high latitudes in the Northern Hemisphere, play an important role in the long-range transport (LRT) of HCHs to the high latitudes from its sources. Being consistent with the cold condensation effect and poleward atmospheric transport in a mean meridional atmospheric circulation simulated by a 2-D atmospheric transport model, as reported by the first part of this study, this modeling study indicates that cold condensation is likely occurring more intensively at the mid-troposphere where rapid declining air temperature results in condensed phase of the chemical over and near its source regions and where stronger winds convey the chemical more rapidly to the polar region during the episodic poleward atmospheric transport events.

Zhang, Lisheng; Ma, Jianmin; Tian, Chongguo; Li, Yifan

2009-12-01

157

Cold fusion experiments using Maxwellian plasmas and sub-atmospheric deuterium gas  

Microsoft Academic Search

Experiments are being performed to initiate the cold fusion process in Maxwellian plasmas and sub-atmospheric deuterium gas. Thus far, apparent neutron counts have been observed using a BF3 probe and Ludlum model 2200 digital counter, and a broad 8.1 MeV peak has been observed using a 3-inch sodium iodide crystal and a Nucleus PCA II multichannel analyzer. The results appear

Mark Prelas; Frederick Boody; Warren Gallaher; Edbertho Leal-Quiros; David Mencin; Scott Taylor

1990-01-01

158

Atomic Oxygen Maximization in High-Voltage Pulsed Cold Atmospheric Plasma Jets  

Microsoft Academic Search

This paper presents a new device generating high-voltage pulsed cold atmospheric plasma jets. With these plasmas, the quantity of atomic oxygen (and, accordingly, the chemical activity) is a lot higher than that in previous researches. The main characteristic of the new device is the usage of three tubular needle-type electrodes connected in parallel. By applying high-voltage pulses (with 20-30-kV amplitude,

Nicolae Georgescu; Cristian P. Lungu; Andreea Roxana Lupu; Mariana Osiac

2010-01-01

159

Impact of Atmospheric Pressure on Oceanic Angular Momentum  

NASA Astrophysics Data System (ADS)

While the oceans respond dynamically to high-frequency variations in atmospheric pressure, at low frequencies the oceans act like an inverted barometer, responding isostatically to the imposed pressure variations. Since atmospheric pressure is usually not included in the forcing of oceanic general circulation models, the dynamic response of the oceans at high frequencies is usually not included in the angular momentum computed from such models. Instead, the oceans are usually assumed to respond as an inverted barometer when computing the oceanic angular momentum. The neglect of surface pressure when forcing an ocean model can therefore be expected to degrade the agreement of the modeled oceanic angular momentum with Earth orientation observations at high frequencies. Here, atmospheric pressure is included in the forcing of a non-Boussinesq model of the global oceans. The oceanic angular momentum computed from this pressure-forced ocean model is compared to that computed assuming an isostatic response of the oceans. It is also compared to Earth orientation observations from which atmospheric effects have been removed.

Gross, R. S.; Song, Y.

2009-12-01

160

Pressure chamber tests of eustachian tube function document lower efficiency in adults with colds when compared to without colds.  

PubMed

Abstract Conclusions: Fractional gradient equilibrated (FGE) for ears with applied positive but not negative middle ear (ME)-ambient pressure gradients is highly sensitive to a cold-like illness (CLI). Objective: The sequential development of eustachian tube (ET) dysfunction, ME under-pressure, and otitis media (OM) characterizes many children during a CLI. If linked, OM burden would be lessened by interventions that promote/preserve good ET function during a CLI. Evaluating this requires a quantitative ET function test for MEs with an intact tympanic membrane responsive to a CLI. Methods: Pressure chamber testing of ET function was performed at +200 and -200 daPa in 3 groups of adults: group I, 21 subjects with an extant CLI and groups II and III, 14 and 57 adults, respectively, without a CLI. ME-chamber pressure gradient was recorded by tympanometry before and after the subject swallowed twice. ET functional efficiency was quantified as the FGE, which was then compared among groups using a Mann-Whitney U test. Results: At chamber pressures of 200 daPa, the ME-chamber pressure gradient was negative, and FGE was low and not different among groups. At chamber pressures of -200 daPa that gradient was positive, and FGE was significantly higher in groups II and III when compared with group I. PMID:24834936

Doyle, William J; Singla, Alok; Banks, Juliane; El-Wagaa, Jenna; Swarts, J Douglas

2014-07-01

161

The acidification of lipid film surfaces by non-thermal DBD at atmospheric pressure in air  

NASA Astrophysics Data System (ADS)

We studied the acidifying efficiency of a cold atmospheric pressure plasma treatment and ambient air as a working gas on lipid films. Acidification of a thin water film could be observed on plasma-treated surfaces of wool wax, pork sebum and human lipids. This pH shift was partly attributable to NOx species and to the formation of nitric acid in the upper layers of the substrates. The acidic compounds on the lipid surfaces resulted in pH shifts for up to 2 h after plasma exposure, which might be beneficial for pH-targeted therapies in dermatology.

Helmke, A.; Hoffmeister, D.; Mertens, N.; Emmert, S.; Schuette, J.; Vioel, W.

2009-11-01

162

LNG Vehicle High-Pressure Fuel System and ''Cold Energy'' Utilization  

Microsoft Academic Search

A high-pressure fuel system for LNG vehicles with direct-injection natural gas engines has been developed and demonstrated on a heavy-duty truck. A new concept for utilizing the ''cold energy'' associated with LNG vehicles to generate mechanical power to drive auxiliary equipment (such as high-pressure fuel pumps) has also been developed and demonstrated in the laboratory. The high-pressure LNG fuel system

Charles A. powers; T. Craig Derbidge

2001-01-01

163

Electrochemical reduction of high pressure CO 2 at a Cu electrode in cold methanol  

Microsoft Academic Search

The electrochemical reduction of high pressure CO2 with a Cu electrode in cold methanol was investigated. A high pressure stainless steel vessel, with a divided H-type glass cell, was employed. The main products from CO2 by the electrochemical reduction were methane, ethylene, carbon monoxide and formic acid. In the electrolysis of high pressure CO2 at low temperature, the reduction products

Satoshi Kaneco; Kenji Iiba; Hideyuki Katsumata; Tohru Suzuki; Kiyohisa Ohta

2006-01-01

164

Plasma cathode preionized atmospheric pressure HF chemical laser  

NASA Astrophysics Data System (ADS)

The performance of an electric discharge, plasma-cathode-preionized, atmospheric-pressure HF chemical laser was investigated and the laser was geometrically optimized. The preionization electron density was measured at atmospheric pressure in helium and in a mixture of SF 6 + H 2 diluted by helium. The measured preionization density is ne ? 6.7 × 10 9-2 × 10 10cm -3, which is higher than the minimum critical density required for a self-sustained, homogeneous discharge of atmospheric-pressure electronegative gases. We have found improvement in laser specific energy for a diluted gas mixture of SF 6 + H 2 due to reduction in SF 6 concentration. The effects of inter-electrode gap height and plasma cathode grid width on laser performance were also investigated and are reported.

Kalisky, Y.; Waichman, K.; Kamin, S.; Chuchem, D.

1997-02-01

165

DBD treatment of polyethylene terephthalate: Atmospheric versus medium pressure treatment  

Microsoft Academic Search

In this paper, polyethylene terephthalate (PET) films are modified by a dielectric barrier discharge (DBD) in a helium\\/air mixture at medium (6.6 kPa) and atmospheric pressure. Surface analysis and characterization of the plasma-treated PET films is performed using contact angle measurements, X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The polymer films, modified with the DBD at medium and atmospheric

N. De Geyter; R. Morent; C. Leys; L. Gengembre; E. Payen; S. Van Vlierberghe; E. Schacht

2008-01-01

166

Plant adaptation to low atmospheric pressures: potential molecular responses  

NASA Technical Reports Server (NTRS)

There is an increasing realization that it may be impossible to attain Earth normal atmospheric pressures in orbital, lunar, or Martian greenhouses, simply because the construction materials do not exist to meet the extraordinary constraints imposed by balancing high engineering requirements against high lift costs. This equation essentially dictates that NASA have in place the capability to grow plants at reduced atmospheric pressure. Yet current understanding of plant growth at low pressures is limited to just a few experiments and relatively rudimentary assessments of plant vigor and growth. The tools now exist, however, to make rapid progress toward understanding the fundamental nature of plant responses and adaptations to low pressures, and to develop strategies for mitigating detrimental effects by engineering the growth conditions or by engineering the plants themselves. The genomes of rice and the model plant Arabidopsis thaliana have recently been sequenced in their entirety, and public sector and commercial DNA chips are becoming available such that thousands of genes can be assayed at once. A fundamental understanding of plant responses and adaptation to low pressures can now be approached and translated into procedures and engineering considerations to enhance plant growth at low atmospheric pressures. In anticipation of such studies, we present here the background arguments supporting these contentions, as well as informed speculation about the kinds of molecular physiological responses that might be expected of plants in low-pressure environments.

Ferl, Robert J.; Schuerger, Andrew C.; Paul, Anna-Lisa; Gurley, William B.; Corey, Kenneth; Bucklin, Ray

2002-01-01

167

Is atmospheric pressure change an Independent risk factor for hemoptysis?  

PubMed Central

Objective: Hemoptysis is one of the most important and challenging symptoms in pulmonary medicine. Because of the increased number of patients with hemoptysis in certain periods of the year, we aimed to investigate whether atmospheric changes have an effect on the development of hemoptysis with or without a secondary cause. Methods: The data of patients presenting with hemoptysis between January 2006 and December 2011 were analyzed. Data on the daily atmospheric pressure (hectopascal, hPa), relative humidity (%), and temperature (o C) during that time were obtained. Results: A total of 232 patients with hemoptysis, 145 male (62.5%) and 87 female (37.5%) with an average age of 48.1(±17.6), were admitted to our hospital between 2006 and 2011. The highest admission rates were in the spring season, the highest in May (n=37, 15.9%), and the lowest admission rates were in December (n=10, 4.3%). A statistically significant negative correlation was found between the number of hemoptysis cases and mean atmospheric pressure but no relative humidity or outdoor temperature. Conclusion: Hemoptysis is very much influenced by weather factors; in particular, low atmospheric pressures significantly affect the development of hemoptysis. Fluctuations in atmospheric pressure may also play a role in hemoptysis.

Araz, Omer; Ucar, Elif Yilmazel; Akgun, Metin; Aydin, Yener; Meral, Mehmet; Saglam, Leyla; Kaynar, Hasan; Gorguner, Ali Metin

2014-01-01

168

Peptide Fragmentation Induced by Radicals at Atmospheric Pressure  

PubMed Central

A novel ion dissociation technique, which is capable of providing an efficient fragmentation of peptides at essentially atmospheric pressure conditions, is developed. The fragmentation patterns observed often contain c-type fragments that are specific to ECD/ETD, along with the y-/b- fragments that are specific to CAD. In the presented experimental setup, ion fragmentation takes place within a flow reactor located in the atmospheric pressure region between the ion source and the mass spectrometer. According to a proposed mechanism, the fragmentation results from the interaction of ESI-generated analyte ions with the gas-phase radical species produced by a corona discharge source.

Vilkov, Andrey N.; Laiko, Victor V.; Doroshenko, Vladimir M.

2009-01-01

169

Atmospheric pressure microplasma jet as a depositing tool  

SciTech Connect

An atmospheric pressure microplasma jet is developed for depositing homogeneous thin films from C{sub 2}H{sub 2}. The adjustment of the gas flow through the microplasma jet assures optimal flow conditions as well as minimizes deposition inside the jet. In addition, the formation of an argon boundary layer surrounding the emerging plasma beam separates the ambient atmosphere from the flow of growth precursor. Thereby the incorporation of nitrogen and oxygen from the ambient atmosphere into the deposited film is suppressed. Soft polymerlike hydrogenated amorphous carbon (a-C:H) films are deposited at the rate of a few nm/s on the area of a few square millimeters.

Benedikt, J.; Focke, K.; Yanguas-Gil, A.; Keudell, A. von [Arbeitsgruppe Reaktive Plasmen, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

2006-12-18

170

Pressure-transient behavior during cold water injection  

Microsoft Academic Search

During injection testing, pressures in geothermal;\\u000awells sometimes decline after an initial period of;\\u000aincrease despite continued injection. The injection;\\u000atests carried out at the Yutsubo geothermal field in;\\u000aKyushu, Japan exhibit this peculiar behavior.;\\u000aDuring injection testing of Yatsubo well YT-2,;\\u000aobserved downhole pressures eventually began to;\\u000adecline despite sustained injection rates. We have;\\u000acarried out numerical simulation studies

Shinsuke Nakao; Tsuneo Ishido

1996-01-01

171

Generation of Atmospheric-Pressure Glow Discharge and Its Applications 2.Production of Atmospheric-Pressure Glow Discharge  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure glow (APG) discharge is one of the more interesting fields of recent study owing to its possible applications in plasma processing, surface treatment, sterilization, etc. This field was developed by Okazaki and Kogoma et al. of the Sophia University group in 1988, and has spread world wide. Usually, a glow discharge is difficult to keep stable at atmospheric gas pressure because glow-to-arc transition occurs due to thermalization of the plasma. However, some methods have been presented to produce stable glow plasma at atmospheric gas pressure; 1) inserting a dielectric plate between electrodes, 2) applying pulsed voltage having a pulse width shorter than the thermalization time, 3) use of a micro-hollow cathode configuration, etc. This article describes the generation of AGP mainly using the dielectric plate. Numerical analysis based on continuity equations of charged species and Poisson's equation is also described.

Takaki, Koichi; Fujiwara, Tamiya; Tochikubo, Fumiyoshi

172

Engineering a laser remote sensor for atmospheric pressure and temperature  

NASA Technical Reports Server (NTRS)

A system for the remote sensing of atmospheric pressure and temperature is described. Resonant lines in the 7600 Angstrom oxygen A band region are used and an organic dye laser beam is tuned to measure line absorption changes with temperature or pressure. A reference beam outside this band is also transmitted for calibration. Using lidar techniques, profiling of these parameters with altitude can be accomplished.

Kalshoven, J. E., Jr.; Korb, C. L.

1978-01-01

173

Effect of cosmic rays on atmospheric pressure under mountain conditions  

Microsoft Academic Search

The phenomenological model of condensation interaction between galactic cosmic rays (GCRs) and water vapor, which makes it\\u000a possible to estimate atmospheric pressure variations at different altitudes with changing GCR flux, has been developed. It\\u000a has been indicated that pressure should increase at all altitudes in the considered interval (0–5 km above sea level) during\\u000a Forbush decreases. Therefore, the correlation between

M. B. Bogdanov; A. N. Surkov; A. V. Fedorenko

2006-01-01

174

Hypobaric biology: Arabidopsis gene expression at low atmospheric pressure.  

PubMed

As a step in developing an understanding of plant adaptation to low atmospheric pressures, we have identified genes central to the initial response of Arabidopsis to hypobaria. Exposure of plants to an atmosphere of 10 kPa compared with the sea-level pressure of 101 kPa resulted in the significant differential expression of more than 200 genes between the two treatments. Less than one-half of the genes induced by hypobaria are similarly affected by hypoxia, suggesting that response to hypobaria is unique and is more complex than an adaptation to the reduced partial pressure of oxygen inherent to hypobaric environments. In addition, the suites of genes induced by hypobaria confirm that water movement is a paramount issue at low atmospheric pressures, because many of gene products intersect abscisic acid-related, drought-induced pathways. A motivational constituent of these experiments is the need to address the National Aeronautics and Space Administration's plans to include plants as integral components of advanced life support systems. The design of bioregenerative life support systems seeks to maximize productivity within structures engineered to minimize mass and resource consumption. Currently, there are severe limitations to producing Earth-orbital, lunar, or Martian plant growth facilities that contain Earth-normal atmospheric pressures within light, transparent structures. However, some engineering limitations can be offset by growing plants in reduced atmospheric pressures. Characterization of the hypobaric response can therefore provide data to guide systems engineering development for bioregenerative life support, as well as lead to fundamental insights into aspects of desiccation metabolism and the means by which plants monitor water relations. PMID:14701916

Paul, Anna-Lisa; Schuerger, Andrew C; Popp, Michael P; Richards, Jeffrey T; Manak, Michael S; Ferl, Robert J

2004-01-01

175

Seasonal-scale Observational Data Analysis and Atmospheric Phenomenology for the Cold Land Processes Experiment  

NASA Technical Reports Server (NTRS)

The Cold Land Processes Experiment (CLPX) experiment emphasized the development of a strong synergism between process-oriented understanding, land surface models and microwave remote sensing. Our work sought to investigate which topographically- generated atmospheric phenomena are most relevant to the CLPX MSA's for the purpose of evaluating their climatic importance to net local moisture fluxes and snow transport through the use of high-resolution data assimilation/atmospheric numerical modeling techniques. Our task was to create three long-term, scientific quality atmospheric datasets for quantitative analysis (for all CLPX researchers) and provide a summary of the meteorologically-relevant phenomena of the three MSAs (see Figure) over northern Colorado. Our efforts required the ingest of a variety of CLPX datasets and the execution an atmospheric and land surface data assimilation system based on the Navier-Stokes equations (the Local Analysis and Prediction System, LAPS, and an atmospheric numerical weather prediction model, as required) at topographically- relevant grid spacing (approx. 500 m). The resulting dataset will be analyzed by the CLPX community as a part of their larger research goals to determine the relative influence of various atmospheric phenomena on processes relevant to CLPX scientific goals.

Poulos, Gregory S.; Stamus, Peter A.; Snook, John S.

2005-01-01

176

Cold plasma reduction of Salmonella and Escherichia coli O157:H7 on almonds using ambient pressure gases.  

PubMed

Contamination of raw nuts, including almonds, is a food safety concern. Cold plasma is a novel antimicrobial intervention that can eliminate foodborne pathogens. The objective of this work was to evaluate the efficacy of rapid cold plasma treatments in eliminating Salmonella and Escherichia coli O157:H7 from dry almonds. Three isolates of Salmonella (S. Anatum F4317, S. Stanley H0558, and S. Enteritidis PT30) and 3 isolates of E. coli O157:H7 (C9490, ATCC 35150, and ATCC 43894) were separately grown and spot-inoculated (10 ?L) onto whole almonds and allowed to dry for 10 min. Inoculated almonds were treated with a cold plasma jet, with treatment variables evaluated in a factorial design for each isolate: time, distance, and feed gas. Treatment time was 0 s (control), 10 s, or 20 s. Distance from the emitter was 2, 4, or 6 cm. Feed gas was dry air or nitrogen. After treatment, the almonds were sampled using swabs. Survivors were enumerated on tryptic soy agar (TSA) plates. Cold plasma significantly reduced both pathogens on almonds. The greatest reduction observed was 1.34 log cfu/mL reduction of E. coli O157:H7 C9490 after 20 s treatment at 6 cm spacing. The interaction of treatment time with distance from plasma emitter head was complex, and isolate-dependent. Longer duration of treatment did not always result in enhanced reductions. In general, nitrogen as a feed gas resulted in a reduced antimicrobial efficacy compared to dry air. These results indicate that short pulses of atmospheric pressure cold plasma can significantly reduce Salmonella and E. coli O157:H7 on almonds. PMID:22384964

Niemira, Brendan A

2012-03-01

177

Global Atmospheric Pressure Effects of the October 30, 1961, Explosion  

Microsoft Academic Search

The atmospheric pressure waves set off by the explosion of October 30, 1961, were traced over a large portion of the world, including the antipodes in the Antarctic, by means of analyses of available ordinary microbarograph records. The observed geographic variations in propagation speed and maximum amplitude are examined with the aid of air density and wind analyses. Comparison is

H. Wexler; W. A. Hass

1962-01-01

178

PLANT ADAPTATION TO LOW ATMOSPHERIC PRESSURES: POTENTIAL MOLECULAR RESPONSES  

Microsoft Academic Search

(Abstract) There is an increasing realization that it may,be impossible,to attain earth normal atmospheric pressures in orbital, lunar or Martian greenhouses; simply because the construction materials do not exist to meet ,the extraordinary constraints imposed ,by balancing ,high engineering requirements against high lift costs. This equation essentially dictates that NASA have in place the capability to grow ,plants at reduced

Robert J. Ferl

179

Electrode erosion in arc discharges at atmospheric pressure  

Microsoft Academic Search

An experimental investigation was performed in an effort to measure and increase lifetime of electrodes in an arcjet thruster. The electrode erosion of various anode and cathode materials was measured after tests in an atmospheric pressure nitrogen arc discharge at powers less than 1 kW. A free-burning arc configuration and a constricted arc configuration were used to test the materials.

1985-01-01

180

Atmospheric pressure and suicide attempts in Helsinki, Finland  

NASA Astrophysics Data System (ADS)

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 < 0.001), and may explain the clustering of suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between 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.

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

2012-11-01

181

Atmospheric pressure helium afterglow discharge detector for gas chromatography  

DOEpatents

An apparatus for providing a simple, low-frequency, electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

Rice, G.; D'Silva, A.P.; Fassel, V.A.

1985-04-05

182

Atmospheric pressure helium afterglow discharge detector for gas chromatography  

DOEpatents

An apparatus for providing a simple, low-frequency electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

Rice, Gary (Gloucester, VA); D'Silva, Arthur P. (Ames, IA); Fassel, Velmer A. (Ames, IA)

1986-05-06

183

Electron Heating in Pulsed Atmospheric Pressure Glow Discharges  

Microsoft Academic Search

Atmospheric pressure glow discharges in air and noble gases have been operated by using microhollow cathode discharges as plasma cathodes [1]. In these discharges the electron energy distribution is determined by the value of the reduced electric field (E\\/N). Pulsing the discharges causes the electron energy distribution to shift into an energy range where the ionization rate increases strongly. In

Robert H. Stark; Frank Leipold; Chunqi Jiang; Hisham Merhi; Karl H. Schoenbach

2000-01-01

184

High electron density, atmospheric pressure air glow discharges  

Microsoft Academic Search

The pulsed electron heating effect has been studied on an atmospheric pressure air glow discharge. Application of a high voltage pulse causes a shift in the electron energy distribution function to higher energies. This causes a temporary increase of the ionization rate and consequently an increase of the electron density. The electron density after a 10 ns pulse application to

Frank Leipold; Abdel-Aleam H. Mohamed; Karl H. Schoenbach

2002-01-01

185

Physics of dielectric surface flashover at atmospheric pressure  

Microsoft Academic Search

The limits of the applicability of DC, AC, or pulsed high voltage are determined by breakdown along insulators or insulating support structures. It is of major technical importance to predict breakdown voltages for given structures, with parameters such as geometry, material, and temporal characteristics of the applied voltage. The impact of atmospheric conditions such as humidity, pressure, temperature, and types

John Krile; A. Neuber; James Dickens; Hermann Krompholz

2003-01-01

186

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces.  

National Technical Information Service (NTIS)

The purpose of this project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. This goal has been achieved with the invention of the atmospheric-pressure plasma jet. This device s...

R. F. Hicks G. S. Selwyn

1999-01-01

187

Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

188

Atmospheric pressure plasma diagnostics by OES, CRDS and TALIF  

Microsoft Academic Search

Nanosecond repetitively pulsed (NRP) discharges were used to generate atmospheric pressure plasmas in air or nitrogen preheated at 1000 K. In order to understand the physico-chemical mechanisms that control the number densities of active species, in situ optical diagnostic techniques were developed. The ground state of atomic oxygen was measured by two-photon absorption laser induced fluorescence (TALIF), the density of

G D Stancu; F Kaddouri; D A Lacoste; C O Laux

2010-01-01

189

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of heavy metal waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly undertaking for the US Department of Energy. Our technology shows great promise for mitigating the cost of this clean up effort.

Hicks, Robert F.; Herrmann, Hans W.

2002-06-01

190

Low temperature atmospheric pressure plasma sources for microbial decontamination  

Microsoft Academic Search

The aim of this paper is to provide a survey of plasma sources at atmospheric pressure used for microbicidal treatment. In order to consider the interdisciplinary character of this topic an introduction and definition of basic terms and procedures are given for plasma as well as for microbicidal issues. The list of plasma sources makes no claim to be complete,

J. Ehlbeck; U. Schnabel; M. Polak; J. Winter; Th von Woedtke; R. Brandenburg; T. von dem Hagen; K.-D. Weltmann

2011-01-01

191

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of nuclear waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly undertaking for the U.S. Department of Energy. Our technology shows great promise for mitigating the cost of this clean up effort.

Hicks, Robert F.; Herrmann, Hans W.

2001-06-01

192

Atmospheric Pressure Plasma Jet for Chem\\/Bio Warfare Decontamination  

Microsoft Academic Search

Atmospheric Pressure Plasma Jet (APPJ) technology may provide a much needed method of CBW decontamination which, unlike traditional decon methods, is dry and nondestructive to sensitive equipment and materials. The APPJ discharge uses a high-flow feedgas consisting primarily of an inert carrier gas, such as He, and a small amount of a reactive additive, such as O2, which flows between

Hans W. Herrmann; Ivars Henins; Jaeyoung Park; Gary S. Selwyn

1999-01-01

193

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of radioactive waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly undertaking for the US Department of Energy. Our technology shows great potential for accelerating this clean up effort.

Hicks, Robert F.; Herrmann, Hans W.

2003-06-01

194

Application of atmospheric-pressure nonequilibrium plasma in air decontamination  

Microsoft Academic Search

Summary form only given. In atmospheric-pressure gas discharge system, slit discharge (SD), has been developed for the removing of biological and chemical contaminants from the ambient air. The system consists of multiple plasma grids stacked perpendicularly to the air flow. The performance of the system has been tested using the surrogates of biological and chemical warfare agents. The results of

Shu-Min Yin; Y. Naumova; S. Babko-Malyi; M. Orrico

2006-01-01

195

CF4 abatement by atmospheric pressure microwave plasma torch  

Microsoft Academic Search

This article deals with CF4 abatement by electrodeless atmospheric pressure microwave plasma torch. The plasma abatement device is attached to the vacuum pump, which discharges the nitrogen gas with contaminants. The abatement was carried out using oxygen and air as an additive gases. The destruction and removal efficiency (DRE) of more than 98% was achieved for tetrafluoromethane(CF4). The detailed characterization

Y. C. Hong; H. S. Uhm

2003-01-01

196

Oxide surface cleaning by an atmospheric pressure plasma  

Microsoft Academic Search

In this study, an atmospheric pressure plasma was generated using a dielectric barrier discharge (DBD) with a perforated dielectric covered electrode and its effect on the cleaning of organic materials on oxides such as indium tin oxide (ITO) and magnesium oxide (MgO) was investigated. He and O2 were used as the ignition gas and cleaning gas, respectively. In addition to

Chang Heon Yi; Chang Hyun Jeong; Yong Hyuk Lee; Young Wook Ko; Geun Young Yeom

2004-01-01

197

Power ultrasound interaction with DC atmospheric pressure electrical discharge  

Microsoft Academic Search

The effect of power ultrasound application on DC hollow needle to plate atmospheric pressure electrical discharge enhanced by the flow of air through the needle electrode was studied experimentally. It was found that applying ultrasound increases discharge volume. In this volume take place plasmachemical processes, used in important ecological applications such as the production of ozone, VOC decomposition and de-NOx

Rudolf Bálek; Stanislav Pekárek; Zuzana Bartáková

2006-01-01

198

ANNUAL REPORT. ATMOSPHERIC-PRESSURE PLASMA CLEANING OF CONTAMINATED SURFACES  

EPA Science Inventory

The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of nuclear waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly unde...

199

The effects of powder properties on in-flight particle velocity and deposition process during low pressure cold spray process  

Microsoft Academic Search

In cold spray process, impacting velocity and critical velocity of particles dominate the deposition process and coating properties for given materials. The impacting velocity and critical velocity of particles depend on the powder properties and cold spray conditions. In the present study, the in-flight particle velocity of copper powder in low pressure cold spraying was measured using an imaging technique.

Xian-Jin Ning; Jae-Hoon Jang; Hyung-Jun Kim

2007-01-01

200

On the cold start problem in transient simulations with coupled atmosphere-ocean models  

SciTech Connect

Finite computer resources force compromises in the design of transeint numerical experiments with coupled atmosphere-ocean gneeral circulation models which, in the case of global warming simulations, normally preclude a full integration from the undstrubed pre-industrial state. The start of the inegation at a later time from a climate state which, in contrast to the ture climate, is initially in equilibrium then induces a cold start error. Using linear response theory a genreal expression for the cold start error is derivved. The theory is applied to the Hamburg CO{sub 2} sceanrio simulations. An attempt to estimate the global-mean-temperature response of the model to a CO{sub 2} doubling was unsuccessful because of the non-inearity of the system. However, an alternative derivation, based on the transient simulation itself, yielded a cold start error which explained the initial retardation of the Hamburg global warming curve relative to the IPCC results obtained with a simple box-diffusion-upwelling model. In the case of the sea level the behaviour of the model is apparently more linear. Teh cold start error estimations based on a CO{sub 2} doubling experiment and on an experiment with gradually increasing CO{sub 2} (scenario A) are very similar and explain about two thirds of the coupled model retardation relative to the IPCC results. 15 refs., 8 figs., 5 tabs.

Hasselmann, K.; Maier-Reimer, E. [Max-Planck Institut fuer Meteorologie, Hamburg (Germany); Sausen, R. [Deutsche Forschungsantalt fuer Luft- und Raumfahrt, Wessling (Germany)] [and others

1993-11-01

201

Study of atmospheric pressure discharges with a novel hybrid code  

NASA Astrophysics Data System (ADS)

Numerical simulations bear special significance in helping to understand the phenomena taking place in the atmospheric discharges as the diagnostic capabilities are severely limited there due to small sizes of such discharges. In this work we study atmospheric pressure discharges with a fully self-consistent hybrid code, where the kinetically treated electron component is calculated on GPU using the PIC/MCC approach and ions are treated under the fluid approximation on CPU. The resulting code is fast, because the computationally intensive kinetic algorithm is parallelized on GPU, flexible, because it is straightforward to include complex chemistry processes for the ion component in the fluid model, and allows to capture all the essential physics due to quite general assumptions underlying the model. A comparison with fully fluid simulations is made. We demonstrate with our code that the kinetic description of electrons is important even for the atmospheric pressure discharges.

Eremin, Denis; Hemke, Torben; Brinkmann, Ralf-Peter; Mussenbrock, Thomas

2012-10-01

202

Can electron multipacting explain the pressure rise in a cold bore superconducting undulator?  

NASA Astrophysics Data System (ADS)

Preliminary studies performed with the cold bore superconducting undulator installed in the ANKA (Angstrom source Karlsruhe) storage ring suggest that the beam heat load is mainly due to the electron wall bombardment. Electron bombardment can both heat the cold vacuum chamber and induce an increase in the pressure because of gas desorption. In this contribution we compare the measurements of the pressure in a cold bore performed in the electron storage ring ANKA with the predictions obtained using the equations of gas dynamic balance in a cold vacuum chamber exposed to synchrotron radiation and electron bombardment. The balance results from two competing effects: the photon and electron stimulated desorption of the gas contained in the surface layer of the chamber wall and of the gas cryosorbed, and the cryopumping by the cold surface. We show that photodesorption alone cannot explain the experimental results and that electron multipacting is needed to reproduce the observed pressure rise. Electron bombardment can at the same time explain the observed beam heat load.

Casalbuoni, S.; Schleede, S.; Saez de Jauregui, D.; Hagelstein, M.; Tavares, P. F.

2010-07-01

203

Preparation of Copper Nanoparticles Using Dielectric Barrier Discharge at Atmospheric Pressure and its Mechanism  

NASA Astrophysics Data System (ADS)

Dielectric barrier discharge (DBD) cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide (CuO). Power X-ray diffraction (XRD) was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra (OES) were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen (H) radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles.

Di, Lanbo; Zhang, Xiuling; Xu, Zhijian

2014-01-01

204

Model of a stationary microwave argon discharge at atmospheric pressure  

SciTech Connect

The many applications of microwave gas discharges at atmospheric pressure in various fields of science, technology and medicine require an adequate model of these discharges. Such a model is based on the electromagnetic wave's propagation properties and on the elementary processes in the discharge bulk. In contrast to the microwave discharges at low-gas pressures, where many elementary processes might be ignored because of their negligible contribution to the electron and heavy particle's balance equations, for such discharges at atmospheric pressure the consideration of a large number of collisional processes is mandatory. For the build of a successful discharge-column model one needs three important quantities, notably the power {theta} necessary for sustaining an electron - ion pair, electron - neutral collision frequency for momentum transfer v{sub en}, and gas temperature T{sub g}. The first two key parameters are obtained by a collisional-radiative model of the argon at atmospheric pressure, while the microwave frequency {omega}/2{pi} = 2.45 GHz, plasma column radius R, gas pressure p and gas temperature T{sub g} are fixed external parameters determined by the experimental conditions. Here, we present a model of a capillary argon microwave plasma column with a length L {approx_equal} 14 cm, sustained by wave power of 110 W - the model yields the longitudinal distributions of the plasma density, expended wave power, wave electric field magnitude, and complex wave number.

Zhelyazkov, I. [Faculty of Physics, Sofia University, BG-1164 Sofia (Bulgaria); Pencheva, M.; Benova, E. [Department for Language Teaching and International Students, Sofia University, BG-1111 Sofia (Bulgaria)

2008-03-19

205

Radio jet refraction in galactic atmospheres with static pressure gradients  

NASA Technical Reports Server (NTRS)

A theory of double radio sources which have a 'Z' or 'S' morphology is proposed, based on the refraction of radio jets in the extended atmosphere of an elliptical galaxy. The model describes a collimated jet of supersonic material bending self-consistently under the influence of external static pressure gradients. Gravity and magnetic fields are neglected in the simplest case except insofar as they determine the static pressure distribution. The calculation is a straightforward extension of a method used to calculate a ram-pressure model for twin radio trails ('C' morphology). It may also be described as a continuous-jet version of a buoyancy model proposed in 1973. The model has the added virtue of invoking a galactic atmosphere similar to those already indicated by X-ray measurements of some other radio galaxies and by models for the collimation of other radio jets.

Henriksen, R. N.; Vallee, J. P.; Bridle, A. H.

1981-01-01

206

Contact-Free Inactivation of Candida albicans Biofilms by Cold Atmospheric Air Plasma  

PubMed Central

Candida albicans is one of the main species able to form a biofilm on almost any surface, causing both skin and superficial mucosal infections. The worldwide increase in antifungal resistance has led to a decrease in the efficacy of standard therapies, prolonging treatment time and increasing health care costs. Therefore, the aim of this work was to demonstrate the applicability of atmospheric plasma at room temperature for inactivating C. albicans growing in biofilms without thermally damaging heat-sensitive materials. This so-called cold atmospheric plasma is produced by applying high voltage to accelerate electrons, which ionize the surrounding air, leading to the production of charged particles, reactive species, and photons. A newly developed plasma device was used, which exhibits a large plasma-generating surface area of 9 by 13 cm (117 cm2). Different time points were selected to achieve an optimum inactivation efficacy range of ?3 log10 to 5 log10 reduction in CFU per milliliter, and the results were compared with those of 70% ethanol. The results obtained show that contact-free antifungal inactivation of Candida biofilms by cold atmospheric plasma is a promising tool for disinfection of surfaces (and items) in both health care settings and the food industry, where ethanol disinfection should be avoided.

Shimizu, Tetsuji; Isbary, Georg; Heinlin, Julia; Karrer, Sigrid; Klampfl, Tobias G.; Li, Yang-Fang; Morfill, Gregor; Zimmermann, Julia L.

2012-01-01

207

Effect of Using Liquid Feedstock in a High Pressure Cold Spray Nozzle  

Microsoft Academic Search

This study investigates the effect of water injection in the high pressure chamber of a cold spray nozzle. A De Laval nozzle\\u000a geometry with constant back pressure and temperature is modeled numerically using Reynolds Stress Model coupled equations.\\u000a Water spray with a droplet size of 10-100 ?m is modeled using both uniform and Rosin-Rammler size distributions. The two-phase\\u000a flow of gas-liquid

E. Farvardin; O. Stier; V. Lüthen; A. Dolatabadi

2011-01-01

208

High-pressure NMR reveals close similarity between cold and alcohol protein denaturation in ubiquitin.  

PubMed

Proteins denature not only at high, but also at low temperature as well as high pressure. These denatured states are not easily accessible for experiment, because usually heat denaturation causes aggregation, whereas cold or pressure denaturation occurs at temperatures well below the freezing point of water or pressures above 5 kbar, respectively. Here we have obtained atomic details of the pressure-assisted, cold-denatured state of ubiquitin at 2,500 bar and 258 K by high-resolution NMR techniques. Under these conditions, a folded, native-like and a disordered state exist in slow exchange. Secondary chemical shifts show that the disordered state has structural propensities for a native-like N-terminal ?-hairpin and ?-helix and a nonnative C-terminal ?-helix. These propensities are very similar to the previously described alcohol-denatured (A-)state. Similar to the A-state, (15)N relaxation data indicate that the secondary structure elements move as independent segments. The close similarity of pressure-assisted, cold-denatured, and alcohol-denatured states with native and nonnative secondary elements supports a hierarchical mechanism of folding and supports the notion that similar to alcohol, pressure and cold reduce the hydrophobic effect. Indeed, at nondenaturing concentrations of methanol, a complete transition from the native to the A-state can be achieved at ambient temperature by varying the pressure from 1 to 2,500 bar. The methanol-assisted pressure transition is completely reversible and can also be induced in protein G. This method should allow highly detailed studies of protein-folding transitions in a continuous and reversible manner. PMID:23284170

Vajpai, Navratna; Nisius, Lydia; Wiktor, Maciej; Grzesiek, Stephan

2013-01-29

209

Effects of atmospheric river landfalls on the cold season precipitation in California  

NASA Astrophysics Data System (ADS)

Effects of atmospheric river (AR) landfalls in the California coast on the cold-season precipitation in California are examined for the cold seasons of 10 water years (WYs) 2001-2010 using observed data and regional modeling in conjunction with AR-landfall inventory based on visual inspections of precipitable water vapor (PWV) from remote sensing and reanalysis. The PWV in the SSM/I and SSMIS retrievals and the ERA-Interim reanalysis shows 95 AR-landfall days in the California coast that are almost evenly split between the northern and southern coasts across 37.5N. The CPC/NCEP gridded daily precipitation analysis shows that 10-30% of the cold-season precipitation totals in California have occurred during these AR landfalls. The analysis also reveals that the percentage of precipitation and the precipitation intensity during AR landfalls in California are characterized by strong north-to-south gradient. This north-south contrast in the AR precipitation is reversed for the non-AR precipitation in the coastal range. The frequency of AR landfalls and the cold-season precipitation totals in the Sierra Nevada region are only marginally correlated. Instead, AR landfalls are closely related with the occurrence of heavy precipitation events. The freezing-level altitudes are systematically higher for AR wet days than non-AR wet days indicating warmer low-troposphere during AR storms. Cold season simulations for the 10 WYs 2001-2010 show that the Weather Research and Forecast (WRF) model can reasonably simulate important features in both the seasonal and AR precipitation totals. The daily pattern correlation coefficients between the simulated and ERA-Interim upper-air fields exceed 0.9 for most of the period. This suggests that the simulated temporal variations in the atmospheric circulation agree reasonably with the reanalysis over seasonal time scales, characteristics critical for reliable simulations of regional scale hydrologic cycle. The simulated seasonal and AR precipitation totals also agree reasonably with the CPC/NCEP precipitation analysis. The most notable model errors include the overestimation (underestimation) of the season-total and AR precipitation in the northern (southern) California region. The differences in the freezing-level altitudes during the AR- and non-AR wet days in the simulation agree with those from the ERA-Interim reanalysis. The freezing level altitudes are systematically overestimated in the simulations, suggesting warm biases in the low troposphere. Overall, WRF appears to perform reasonably in simulating the key features in the cold season precipitation related with AR landfalls, an important capability for assessing the impact of global climate variations and change on future hydrology in California.

Kim, Jinwon; Waliser, Duane E.; Neiman, Paul J.; Guan, Bin; Ryoo, Ju-Mee; Wick, Gary A.

2013-01-01

210

A Micromachined Pressure Sensor with Integrated Resonator Operating at Atmospheric Pressure  

PubMed Central

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.

Ren, Sen; Yuan, Weizheng; Qiao, Dayong; Deng, Jinjun; Sun, Xiaodong

2013-01-01

211

Inactivation of biofilm-forming bacteria using cold atmospheric plasmas and potential application for decontamination of fresh foods  

Microsoft Academic Search

Summary form only given. This work aims at evaluating the prospects for using cold atmospheric plasmas to decontaminate fresh produce. Nonthermal atmospheric plasmas have mainly been studied in the past as methods for killing pathogens on surfaces either in medical or environmental contexts. Most of these studies are based on cell inactivation on surfaces such as glass, plastics and metals

D. Molha; T. Brocklehurst; G. Shama; M. G. Kong

2004-01-01

212

Atmospheric Characterization of Cold Exoplanets Using a 1.5-m Space Coronagraph  

NASA Astrophysics Data System (ADS)

We present numerical results of the science performance of the SPICES mission, which aims to characterize the spectro-polarimetric properties of cold exoplanets and circumstellar disks in the visible. We focus on the instrument ability to retrieve the spectral signatures of molecular species, clouds and surface of super-Earths in the habitable zone of solar-type stars. Considering realistic reflected planet spectra and instrument limitation, we show that SPICES could analyse the atmosphere and surface of a few super-Earths within 5 pc of the Sun.

Maire, Anne-Lise; Galicher, Raphaël; Boccaletti, Anthony; Baudoz, Pierre; Schneider, Jean; Cahoy, Kerri; Stam, Daphne; Traub, Wesley

2014-04-01

213

Atmospheric pressure loading parameters from very long baseline interferometry observations  

NASA Technical Reports Server (NTRS)

Atmospheric mass loading produces a primarily vertical displacement of the Earth's crust. This displacement is correlated with surface pressure and is large enough to be detected by very long baseline interferometry (VLBI) measurements. Using the measured surface pressure at VLBI stations, we have estimated the atmospheric loading term for each station location directly from VLBI data acquired from 1979 to 1992. Our estimates of the vertical sensitivity to change in pressure range from 0 to -0.6 mm/mbar depending on the station. These estimates agree with inverted barometer model calculations (Manabe et al., 1991; vanDam and Herring, 1994) of the vertical displacement sensitivity computed by convolving actual pressure distributions with loading Green's functions. The pressure sensitivity tends to be smaller for stations near the coast, which is consistent with the inverted barometer hypothesis. Applying this estimated pressure loading correction in standard VLBI geodetic analysis improves the repeatability of estimated lengths of 25 out of 37 baselines that were measured at least 50 times. In a root-sum-square (rss) sense, the improvement generally increases with baseline length at a rate of about 0.3 to 0.6 ppb depending on whether the baseline stations are close to the coast. For the 5998-km baseline from Westford, Massachusetts, to Wettzell, Germany, the rss improvement is about 3.6 mm out of 11.0 mm. The average rss reduction of the vertical scatter for inland stations ranges from 2.7 to 5.4 mm.

Macmillan, D. S.; Gipson, John M.

1994-01-01

214

Atmospheric-pressure Penning ionization of aliphatic hydrocarbons.  

PubMed

A study has been made of the atmospheric-pressure Penning ionization (APPeI) of aliphatic hydrocarbons (pentane, hexane, heptane, and octane) with long-lived rare gas atoms (Rg*). The metastable rare gas atoms (He*, Ne*, Ar* and Kr*) were generated by the negative-mode corona discharge of atmospheric-pressure rare gases. In the Rg*APPeI mass spectra for aliphatic hyrocarbons, the relative abundances of fragment ions were found to increase in the order of He* --> Ne* --> Ar* --> Kr*. The order is in the opposite direction to the internal energies of the Rg*. The less fragmentation observed for He* may be because the nascent molecular ions [M(+.)]* formed by Penning ionization have lifetimes long enough for them to be collisionally deactivated in the atmospheric-pressure ion source. It was found that the relative abundances of fragment ions in Ar*APPeI increased when the sample pressure in the ion source was reduced. This is attributed to the collision of Ar* with molecular ions followed by fragmentation. PMID:17016831

Hiraoka, Kenzo; Furuya, Hiroko; Kambara, Shizuka; Suzuki, Shigeo; Hashimoto, Yutaka; Takamizawa, Atsushi

2006-01-01

215

Exploration Spacecraft and Space Suit Internal Atmosphere Pressure and Composition  

NASA Technical Reports Server (NTRS)

The design of habitat atmospheres for future space missions is heavily driven by physiological and safety requirements. Lower EVA prebreathe time and reduced risk of decompression sickness must be balanced against the increased risk of fire and higher cost and mass of materials associated with higher oxygen concentrations. Any proposed increase in space suit pressure must consider impacts on space suit mass and mobility. Future spacecraft designs will likely incorporate more composite and polymeric materials both to reduce structural mass and to optimize crew radiation protection. Narrowed atmosphere design spaces have been identified that can be used as starting points for more detailed design studies and risk assessments.

Lange, Kevin; Duffield, Bruce; Jeng, Frank; Campbell, Paul

2005-01-01

216

Computational study of cold atmospheric nanosecond pulsed helium plasma jet in air  

NASA Astrophysics Data System (ADS)

A luminous plasma jet is produced when helium gas issuing into atmospheric pressure ambient air is excited by high voltage nanosecond pulsing of a dielectric covered electrode. A detailed computational modeling study of such a discharge is presented. The dynamics of streamer propagation, its dependence on the diffusional mixing layer between helium and air species, and the role of photoionization are discussed.

Breden, Doug; Miki, Kenji; Raja, Laxminarayan L.

2011-09-01

217

Atmospheric-pressure plasma synthesis of carbon nanotubes  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure radio-frequency discharge (APRFD) has great advantages over vacuum-oriented plasma-enhanced chemical vapour deposition (PECVD) as well as other types of atmospheric-pressure plasma sources in terms of single-walled carbon nanotube (SWCNT) growth. We first provide an overview on the recent advances in PECVD synthesis of CNTs, ranging from low pressure to atmospheric pressure, and then we present our current work focusing on the analysis of reactive species generated in the cathodic plasma sheath for further understanding of the SWCNT growth mechanism in PECVD. It was found that the plasma-generated C2H2 is the main CNT growth precursor in PECVD. Approximately 30% of the CH4 (initial feedstock) was converted into C2H6, C2H4 and C2H2. A trace amount of C2H2 enabled the synthesis of SWCNTs in the thermal chemical vapour deposition (CVD) regime. H2 is necessary to grow SWCNTs using PECVD because H2 suppresses the formation of excess amount of C2H2; however, H2 does not eliminate amorphous carbon even at H2/C2H2 ratios of 300. PECVD using a binary mixture of C2H2 and isotope-modified 13CH4 demonstrated that CH4 does not contribute to CNT growth in C2H2-assisted thermal CVD. Atmospheric-pressure PECVD performed with a He/CH4/H2 system is equivalent to C2H2-assisted thermal CVD without an etching gas. APRFD appears to produce a hidden species, which influences the CNT growth process.

Nozaki, Tomohiro; Yoshida, Shinpei; Karatsu, Takuya; Okazaki, Ken

2011-05-01

218

Atmospheric pressure non-thermal plasma: Sources and applications  

NASA Astrophysics Data System (ADS)

Non-thermal plasma at atmospheric pressure is an inherently unstable object. Nature of discharge plasma instabilities and conditions for observation of uniform non-thermal plasma at atmospheric pressure in different environments will be discussed. Various discharge techniques have been developed, which could support uniform non-thermal plasma with parameters varied in a wide range. Time limitation by plasma instabilities can be overcome by shortening pulse length or by restriction of plasma plug residence time with a fast gas flow. Discharge instabilities leading to formation of filaments or sparks are provoked by a positive feedback between the electric field and plasma density, while the counteracting process is plasma and thermal diffusion. With gas pressure growth the size of plasma fluctuation, which could be stabilized by diffusion, diminishes. As a result, to have long lived uniform plasma one should miniaturize discharge. There exist a number of active methods to organize negative feedback between the electric field and plasma density in order to suppress or, at least, delay the instability. Among them are ballast resistors in combination with electrode sectioning, reactive ballast, electronic feedback, and dielectric barrier across the electric current. The last methods are relevant for ac discharges. In the lecture an overview will be given of different discharge techniques scalable in pressure up to one atmosphere. The interest in this topic is dictated by a potential economic benefit from numerous non-thermal plasma technologies. The spectrum of non-thermal plasma applications is continuously broadening. An incomplete list of known applications includes: plasma-assisted chemical vapor deposition, etching, polymerization, gas-phase synthesis, protective coating deposition, toxic and harmful gas decomposition, destruction of warfare agents, electromagnetic wave shielding, polymer surface modifications, gas laser excitation, odor control, plasma assisted combustion, and gas dynamic flow control. Many of these applications have been developed with low-pressure plasma. Atmospheric pressure non-thermal plasma technologies possess such advantages as simplicity of operation and relatively low cost of equipments. A variety of available discharge techniques provides non-thermal plasma at atmospheric pressure in various gases with parameters covering a wide range in power densities, reduced electric field strengths and current densities. Requirements to non-thermal plasma parameters and sorts of gas for various applications vary widely, too. For any specific application the most appropriate discharge type can be found. The spectrum of discharge devices already existing is surprisingly broad. The problem of a successful choice of a discharge type for a specific application will be discussed. A particular emphasis will be placed on the problem of plasma removal of toxic and harmful species from the gas flow.

Napartovich, A. P.

2008-07-01

219

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

NASA Astrophysics Data System (ADS)

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, bioregenerative life support

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

220

Closed cycle Stirling cryogenic cooler with cold plasma pressure wave generator  

US Patent & Trademark Office Database

A closed cycle Stirling cryogenic cooler, typically utilizing a noble gas (He or like) as a working fluid and containing a pneumatically driven expander interconnected with a low frequency pressure wave generator using a flexible transfer line or conduit, wherein the pressure wave generator includes a sealed gas discharge cavity containing the pressurized working fluid and a plurality of discharge electrodes which are electrically isolated, protrude through the walls of the cavity and are electrically connected to the high frequency pulse voltage supply, thus producing the glow discharge resulting in a cloud of cold plasma, making a so-called "plasmanized gas piston".

2012-06-12

221

Optimizing a remote sensing instrument to measure atmospheric surface pressure  

NASA Technical Reports Server (NTRS)

Atmospheric surface pressure can be remotely sensed from a satellite by an active instrument which measures return echoes from the ocean at frequencies near the 60 GHz oxygen absorption band. The instrument is optimized by selecting its frequencies of operation, transmitter powers and antenna size through a new procedure baesd on numerical simulation which maximizes the retrieval accuracy. The predicted standard deviation error in the retrieved surface pressure is 1 mb. In addition the measurements can be used to retrieve water vapor, cloud liquid water and sea state, which is related to wind speed.

Peckham, G. E.; Gatley, C.; Flower, D. A.

1983-01-01

222

Atmospheric-pressure plasma sources for biomedical applications  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure plasmas (APPs) have attracted great interest and have been widely applied in biomedical applications, as due to their non-thermal and reactive properties, they interact with living tissues, cells and bacteria. Various types of plasma sources generated at atmospheric pressure have been developed to achieve better performance in specific applications. This article presents an overview of the general characteristics of APPs and a brief summary of their biomedical applications, and reviews a wide range of these sources developed for biomedical applications. The plasma sources are classified according to their power sources and cover a wide frequency spectrum from dc to microwaves. The configurations and characteristics of plasma sources are outlined and their biomedical applications are presented.

Park, G. Y.; Park, S. J.; Choi, M. Y.; Koo, I. G.; Byun, J. H.; Hong, J. W.; Sim, J. Y.; Collins, G. J.; Lee, J. K.

2012-08-01

223

Diagnostic methods used for atmospheric pressure thermal arc plasma  

NASA Astrophysics Data System (ADS)

Diagnostic methods used for atmospheric pressure thermal arc plasmas are presented in this paper. An experimental direct current arc plasma torch was used as a source for plasma generation at atmospheric pressure. Overheated water vapor was employed as a plasma-forming gas with an admixture of argon as a shielding gas. A couple of plasma diagnostic methods were invoked to perform the analysis of the generated plasma jet at the nozzle exhaust of the torch. Firstly, an optical emission spectroscopy method was used to determine the chemical composition of the water vapor plasma, and from the obtained spectra, the rotational and excitation temperatures were calculated roughly. Secondly, an enthalpy probe measurement was performed in order to measure the mean temperature and the velocity lengthwise and crosswise in the plasma stream.

Tamoši?nas, A.; Valatkevi?ius, P.; Valin?ius, V.; Grigaitien?, V.; Kavaliauskas, Ž.

2014-05-01

224

Development of a Compact Atmospheric Pressure Plasma Source  

NASA Astrophysics Data System (ADS)

Open plasma sources working at atmospheric pressure have a variety of uses, including applications in both the medical [1] and industrial realms [2]. We will be reporting on the development of a compact RF-driven plasma source. Operation of the system will utilize common mono- and diatomic atmospheric gases [3]. Further diagnostics, including UV-VIS emission spectra and in-situ probing, will be performed and presented. [4pt] [1] Plasma Medicine: Applications of Low-Temperature Gas Plasmas in Medicine and Biology, Ed. M. Laroussi, M. G. Kong, G. Morfill, and W. Stolz, Cambridge Press, 2012.[0pt] [2] A. Fridman, Plasma Chemistry, Cambridge Press, 2008.[0pt] [3] M. Capitelly, C.M. Ferreira, B.F. Gordiets, and A.I. Osipov, Plasma Kinetics in Atmospheric Gases, Springer Series on Atomic, Optical, and Plasma Physics, 2000.

Hyde, Alexander; Kamieneski, Richard; Batishchev, Oleg

2012-10-01

225

Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry  

SciTech Connect

Fractional number density measurements for a rf plasma 'needle' operating at atmospheric pressure have been obtained using a molecular beam mass spectrometer (MBMS) system designed for diagnostics of atmospheric plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility in the form of a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a helium/air mixture. In particular, data for the conversion of atmospheric oxygen and nitrogen into nitric oxide are discussed with reference to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery.

Aranda Gonzalvo, Y.; Whitmore, T.D.; Rees, J.A.; Seymour, D.L.; Stoffels, E. [Hiden Analytical Ltd., 420 Europa Boulevard, Warrington WA5 7UN (United Kingdom); Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2006-05-15

226

Atmospheric pressure chemical ionization of alkanes, alkenes, and cycloalkanes  

Microsoft Academic Search

Normal and cyclic alkanes and alkenes form stable gas-phase ions in air at atmospheric pressure from 40 to 200°C when moisture\\u000a is below 1 ppm. Ionization of alkanes in a 63Ni source favored charge transfer over proton transfer through pathways involving [M?1]+ and [M?3]+ ions. Ion mobility spectra for alkanes showed sharp and symmetrical profiles while spectra for alkenes suggested

Suzanne Ehart Bell; Robert G. Ewing; Gary A. Eicernan; Zeev Karpas

1994-01-01

227

Reaction mechanism of TEOS and O3 atmospheric pressure CVD  

Microsoft Academic Search

The reaction mechanism of TEOS\\/O3 atmospheric pressure CVD was studied for dependence of deposition rate on base material, and for step coverage. Base material dependence of TEOS\\/USG, PSG, BSG and BPSG (on silicon and thermal oxide) was studied. Lower deposition rates and poorer quality of TEOS\\/USG films have been obtained on more hydrophilic substrate surface with high ozone concentration. The

K. Fujino; Y. Nishimoto; N. Tokumasu; K. Maeda

1991-01-01

228

Non-thermal Air Plasma at Atmospheric Pressure  

Microsoft Academic Search

An AC-driven, non-thermal, atmospheric pressure air plasma is generated within the gap separating a disk-shaped metal electrode and a water electrode. The plasma species are identified by emission spectroscopy. The ignition phase and the steady-state are studied by a high-speed CCD camera. It is found that the plasma always initiates at the surface of the water electrode. The plasma exhibits

Xinpei Lu; Leipold Frank; O. Minayeva; Mounir Laroussi

2003-01-01

229

Focusing ions by vortex jet at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A new method for focusing ions at atmospheric pressure by a strongly swirled gas jet is proposed and verified. It is shown that, using the driven swirled jet, it is possible to ensure a significant (tenfold) increase in the efficiency of distant ion sampling as compared to that in the aspiration regime. The influence of recombination losses on the efficiency of vortex-driven take-off of ionized samples is discussed.

Kolomiets, Yu. N.; Pervukhin, V. V.

2011-05-01

230

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

The purpose of this project is to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. In order to accomplish this goal, an understanding of the scientific principles of operating the atmospheric-pressure plasma jet must be achieved. This knowledge can then be applied to the design of a working tool for D & D applications within DOE.

Hicks, Robert F.; Selwyn, Gary S.

2000-06-01

231

Atmospheric-pressure plasma decontamination\\/sterilization chamber  

Microsoft Academic Search

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

Hans W. Herrmann; Gary S. Selwyn

2001-01-01

232

Etching materials with an atmospheric-pressure plasma jet  

Microsoft Academic Search

A plasma jet has been developed for etching materials at atmospheric pressure and between 100 and 0963-0252\\/7\\/3\\/005\\/img10C. Gas mixtures containing helium, oxygen and carbon tetrafluoride were passed between an outer, grounded electrode and a centre electrode, which was driven by 13.56 MHz radio frequency power at 50 to 500 W. At a flow rate of 0963-0252\\/7\\/3\\/005\\/img11, a stable, arc-free discharge

J. Y. Jeong; S. E. Babayan; V. J. Tu; I. Henins; R. F. Hicks; G. S. Selwyn

1998-01-01

233

Atmospheric-pressure stability of energetic phases of carbon  

Microsoft Academic Search

The stability of various energetic phases of carbon is investigated with the use of ab initio pseudopotential total-energy methods. In particular, we examine the atmospheric-pressure stability of the fourfold-coordinated bc8 phase of carbon against transformations to graphitic and diamond structures lying at lower energy. A group-theoretical analysis is used to determine high-symmetry transformation paths to these low-energy structures. Ab initio

C. Mailhiot; A. K. McMahan

1991-01-01

234

Optical diagnosis of atmospheric pressure nonthermal plasma for pollution control  

Microsoft Academic Search

Various kinds of optical diagnosis for atmospheric pressure non-thermal plasma which the authors have examined experimentally, are explained. They are LIF of OH (248nm excitation), NO (226nm), TARIF of O (225nm), Sclieren image, ozone profile observation by the laser absorption, spectrum analysis of the plasma including NO-gamma emission, and streamer propagation. The last can be controlled by the gated IICCD

Tetsuji Oda; Ryo Ono; Kei Takezawa

2005-01-01

235

Double streamer phenomena in atmospheric pressure low frequency corona plasma  

SciTech Connect

Time-resolved images of an atmospheric pressure corona discharge, generated at 50 kHz in a single pin electrode source, show unique positive and negative corona discharge features: a streamer for the positive period and a glow for the negative period. However, unlike in previous reports of dc pulse and low frequency corona discharges, multistreamers were observed at the initial time stage of the positive corona. A possible physical mechanism for the multistreamers is suggested.

Kim, Dan Bee; Jung, H.; Gweon, B.; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2010-07-15

236

The nanogap Pirani—a pressure sensor with superior linearity in an atmospheric pressure range  

NASA Astrophysics Data System (ADS)

We have designed and fabricated a surface micromachined Pirani pressure sensor with an extremely narrow gap between its heater and heatsink (substrate) with superior output linearity in the atmospheric pressure range. The gap size of the device has been reduced to 50 nm by using a layer of PECVD amorphous silicon as a sacrificial layer and a xenon difluoride (XeF2) gas phase etching technique. Such a narrow gap pushes the transition from molecular to continuum heat conduction to pressures beyond 200 kPa. The higher transition pressure increases the measurement range and sensitivity of the gauge in atmospheric pressures. The gas phase etching of the sacrificial layer eliminates stiction problems related to a wet etching process. The active area of the sensor is only a 6 × 50 µm2 microbridge anchored to the substrate at both ends. An innovative fabrication technique was developed which resulted in a virtually flat microbridge with improved mechanical robustness. This process enabled us to have a very well-controlled gap between the microbridge and the substrate. The device was tested in a constant heater temperature mode with pressure ranges from 0.1 to 720 kPa. The heater power was only 3 mW at 101 kPa (atmospheric pressure), which increased to about 8 mW at 720 kPa. The output sensitivity and nonlinearity of the device were 0.55% per kPa at 101 kPa and ±13% of the output full scale, respectively.

Khosraviani, Kourosh; Leung, Albert M.

2009-04-01

237

Synthesis of carbon nanotubes in Atmospheric Pressure PECVD  

NASA Astrophysics Data System (ADS)

We have developed atmospheric pressure radio frequency discharge enhaced CVD system for the catalytic growth of CNTs. APG, which is a kind of dielectric barrier discharge (DBD), is homogeneous and stable, because the dilution gas (He) represses the generation of filamentary discharge. In this study Atmospheric Pressure Glow discharge (APG) was generated without dielectric barrier using a radio frequency (RF:13.56MHz) power source. In the case of RF discharge, dielectric between metalic electrodes is not necessary since ions and electrons are trapped between electrodes, decreasing sustaining voltage of plasma. We tried to synthesize carbon nanotubes by using Atmospheric Pressure RF Glow discharge (APRFG) enhanced CVD. Substrate used in this work was Ni (20nm)/Cr (20nm) thin films on Si wafers deposited with RF sputtering. In the carbon nanotube growing process, He/H2/CH4 mixture was processed in the vaccum chamber operated at 760 Torr, while the electrode was heated up to 700°C. The identification of several radicals from optical emission spectroscopy (OES), the relationship between synthesis of CNTs and plasma characteristics will be presented.

Nozaki, Tomohiro; Goto, Tomoya; Okazaki, Ken; Mangolini, Lorenzo

2004-09-01

238

Transmission geometry laserspray ionization vacuum using an atmospheric pressure inlet.  

PubMed

This represents the first report of laserspray ionization vacuum (LSIV) with operation directly from atmospheric pressure for use in mass spectrometry. Two different types of electrospray ionization source inlets were converted to LSIV sources by equipping the entrance of the atmospheric pressure inlet aperture with a customized cone that is sealed with a removable glass plate holding the matrix/analyte sample. A laser aligned in transmission geometry (at 180° relative to the inlet) ablates the matrix/analyte sample deposited on the vacuum side of the glass slide. Laser ablation from vacuum requires lower inlet temperature relative to laser ablation at atmospheric pressure. However, higher inlet temperature is required for high-mass analytes, for example, ?-chymotrypsinogen (25.6 kDa). Labile compounds such as gangliosides and cardiolipins are detected in the negative ion mode directly from mouse brain tissue as intact doubly deprotonated ions. Multiple charging enhances the ion mobility spectrometry separation of ions derived from complex tissue samples. PMID:24896880

Lutomski, Corinne A; El-Baba, Tarick J; Inutan, Ellen D; Manly, Cory D; Wager-Miller, James; Mackie, Ken; Trimpin, Sarah

2014-07-01

239

Stimulation of wound healing by helium atmospheric pressure plasma treatment  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

240

Atmospheric pressure loading effects on Global Positioning System coordinate determinations  

NASA Technical Reports Server (NTRS)

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. The source of the remaining discrepancy between the modeled and observed loading signal may be the result of (1) anisotropic effects in the Earth's loading response, (2) errors in GPS estimates of tropospheric delay, (3) errors in the surface pressure data, or (4) annual signals in the time series of loading and station heights. In addition, we find that using site dependent coefficients, determined by fitting local pressure to the modeled radial displacements, reduces the variance of the measured station heights as well as or better than using the global convolution sum.

Vandam, Tonie M.; Blewitt, Geoffrey; Heflin, Michael B.

1994-01-01

241

Vortex Threshold: Experimental Results at Martian Atmospheric Pressures  

NASA Astrophysics Data System (ADS)

Many examples of Martian dust devils and tracks left by their passage have been identified in Viking and Mars Orbital Camera images and inferred from lander data (Viking and Mars Pathfinder). Recent surveys suggest that dust devils may be common phenomena on Mars and, unlike Earth, could contribute significantly to the global dust budget. Previous studies have noted the apparent paradox that Martian airborne dust is abundant and only a few microns in diameter yet experiments at Mars pressures suggest current Martian ambient wind speeds are insufficient to lift such fine particles from the surface; speeds of the order of 10s or even 100s of m/s are required. Local wind speeds within terrestrial dust devils are typically much greater than ambient wind speeds, but we have no in-situ measurements of the velocity structure of Mars dust devils and so cannot directly quantify their ability to entrain material. However, by using laboratory simulations we can directly measure the ability of a vortex to lift material of known size and density under a variety of atmospheric pressures. We have constructed a vortex generator consisting of a large vertical cylinder containing a rotor comprising four vertical blades and capable of speeds up to 4500 RPM. Beneath the cylinder is a 2.4 by 2.4 m tabletop which can be covered in particles for threshold tests or instrumented with pressure transducers to measure the pressure structure of the vortex. The distance between the cylinder and the tabletop and the height of the blades within the cylinder can be varied to generate a wide range of geometries and intensities of vortices. Recently, the apparatus has been operated at the NASA-Ames Research Center Mars Surface Wind Tunnel facility to simulate Martian atmospheric conditions. We have measured vortex `saltation' threshold using many types of particles ranging in density from walnut shells (1.1 kg/m-3) to steel grit (7.6 kg/m-3) with particle sizes from 2 to 2000 microns and using atmospheric pressures ranging from 10 mbar (representing current Mars atmospheric conditions) to ambient. As expected, vortex threshold was more difficult to achieve with lower pressure conditions. Only the `optimum' particles (those with low densities and particle sizes ranging from 70 to 350 micron) reached full `saltation' at 10 mbar pressure before the apparatus speed limit was reached. Our results suggest that vortex threshold is directly analogous to boundary layer shear threshold for sand-sized particles at pressure from 65 mbar to ambient. We have used this result to equate vortex and boundary layer results in the sand-sized particle regime and hence to compare vortex threshold data with boundary layer results for smaller particles and lower pressures. We used empirical boundary layer expressions for threshold (corrected for particle size and particle Reynold's number). In all cases, vortex action appears more efficient than boundary layer winds at lifting small dust-sized particles and at lifting all particles at very low pressure. We conclude that Martian dust devils are more efficient mechanisms for particle entrainment than boundary layer winds, not merely because they have enhanced local wind speeds but also through another intrinsic mechanism. We suggest that a lift force caused by the passage of the low-pressure core of the dust devil over the particles would have such an effect and present examples of experimental `pressure-well' measurements at low pressures to support this.

Balme, M.; Greeley, R.; Phoreman, J.; Iversen, J.; Mickelson, B.; Beardmore, G.; Metzger, S.

2002-12-01

242

Modeling of an Atmospheric Pressure Helium Plasma Jet  

NASA Astrophysics Data System (ADS)

Cold atmospheric plasma jets have attracted great interest due to their potential application in fields such as biomedical surface modification. It is now well established that cold plasma jets produced by nanosecond pulsed discharges are in fact a series of rapidly propagating streamer discharges that have been termed ``plasma bullets.'' The goal of this work is to elucidate the role that the diffusion zone, air-helium interactive chemistry and photoionization play in the physics of a single plasma bullet discharge. In this work, we perform several simulations with helium in a 3 mm diameter cavity and a mixed helium-air ambient excited by a 10 kV positive pulse. We utilize a self-consistent, multi-species, two-temperature plasma model with helium-air chemistry and a three-term Helmholtz photoionization model. It was found that the presence of air, which has a higher ionization threshold than helium is crucial to the formation of the bullet. The self-induced electric fields produced at the streamer head at the air-helium interface are what drive the propagation and give the bullet its distinctive ring shape. Although not crucial to bullet formation, including air photoionization resulted in streamer speeds almost twice those seen when photoionization is not included.

Breden, Douglas; Miki, Kenji; Raja, Laxminarayan

2011-11-01

243

Pressurized thermal shock: TEMPEST computer code simulation of thermal mixing in the cold leg and downcomer of a pressurized water reactor. [Creare 61 and 64  

Microsoft Academic Search

The TEMPEST computer program was used to simulate fluid and thermal mixing in the cold leg and downcomer of a pressurized water reactor under emergency core cooling high-pressure injection (HPI), which is of concern to the pressurized thermal shock (PTS) problem. Application of the code was made in performing an analysis simulation of a full-scale Westinghouse three-loop plant design cold

L. L. Eyler; D. S. Trent

1984-01-01

244

Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology  

NASA Technical Reports Server (NTRS)

An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by United Technologies Corp. Aerospace Systems (UTAS, formerly Hamilton Sundstrand) and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle (MPCV). In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure testing with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight project computer model predictions with specific operating conditions.

Button, Amy B.; Sweterlitsch, Jeffrey J.

2013-01-01

245

Changes in Earth's rotation rate caused by zonal tide and their manifestations in atmospheric pressure field  

Microsoft Academic Search

Atmospheric pressure changes associated with tidal changes in the Earth's rotation rate are examined in the example of the semiannual solar tide. The observed semiannual changes in atmospheric pressure at the Earth's surface both qualitatively and quantitatively are attributable to real changes in the Earth's rotation rate caused in turn by the semiannual solar tide. The semiannual atmospheric pressure changes

F. I. Rudyayev

1984-01-01

246

Novel 3D Tissue Engineered Bone Model, Biomimetic Nanomaterials, and Cold Atmospheric Plasma Technique for Biomedical Applications  

NASA Astrophysics Data System (ADS)

This thesis research is consist of four chapters, including biomimetic three-dimensional tissue engineered nanostructured bone model for breast cancer bone metastasis study (Chapter one), cold atmospheric plasma for selectively ablating metastatic breast cancer (Chapter two), design of biomimetic and bioactive cold plasma modified nanostructured scaffolds for enhanced osteogenic differentiation of bone marrow derived mesenchymal stem cells (Chapter three), and enhanced osteoblast and mesenchymal stem cell functions on titanium with hydrothermally treated nanocrystalline hydroxyapatite/magnetically treated carbon nanotubes for orthopedic applications (Chapter four). All the thesis research is focused on nanomaterials and the use of cold plasma technique for various biomedical applications.

Wang, Mian

247

Interfacial heating during low-pressure cold-gas dynamic spraying of aluminum coatings  

Microsoft Academic Search

Low-pressure cold spraying was used to deposit aluminum particles (~25 ?m diameter) on to low carbon steel, and the particle–particle\\u000a interactions of the aluminum coating were analyzed. A simplified energy conservation model was developed to estimate the temperature\\u000a at the interface of the deformed particle during deposition of the powder. The Johnson–Cook model was used to calculate the\\u000a particle flow stress,

M. P. Dewar; A. G. McDonald; A. P. Gerlich

248

Blood pressure and thermal responses to repeated whole body cold exposure: effect of winter clothing  

Microsoft Academic Search

The effect of outdoor clothing and repeated cold exposure on blood pressure, heart rate, skin temperature, and thermal sensation\\u000a was studied in 16 young (18–34 years) and 8 middle-aged (35–51 years) normotensive participants. Four winter clothing ensembles\\u000a were used: regular winter clothing without a hat, with a hat, with an extra pair of pants, and with a hat and an extra pair

Yue Li; Hisham Alshaer; Geoff Fernie

2009-01-01

249

Atmospheric Pressure Plasma Induced Sterilization and Chemical Neutralization  

NASA Astrophysics Data System (ADS)

We are studying chemical neutralization and surface decontamination using atmospheric pressure plasma discharges. The plasma is produced by corona discharge from an array of pins and a ground plane. The array is constructed so that various gases, like argon or helium, can be flowed past the pins where the discharge is initiated. The pin array can be biased using either DC, AC or pulsed discharges. Results indicate that the atmospheric plasma is effective in sterilizing surfaces with biological contaminants like E-coli and bacillus subtilus cells. Exposure times of less than four minutes in an air plasma result in a decrease in live colony counts by six orders of magnitude. Greater exposure times result in a decrease of live colony counts of up to ten orders of magnitude. The atmospheric pressure discharge is also effective in decomposing organic phosphate compounds that are simulants for chemical warfare agents. Details of the decomposition chemistry, by-product formation, and electrical energy consumption of the system will be discussed.

Garate, Eusebio; Evans, Kirk; Gornostaeva, Olga; Alexeff, Igor; Lock Kang, Weng; Wood, Thomas K.

1998-11-01

250

Stable microwave coaxial cavity plasma system at atmospheric pressure  

SciTech Connect

We present a systematic study of the development of a novel atmospheric microwave plasma system for material processing in the pressure range up to 760 torr and the microwave input power up to 6 kW. Atmospheric microwave plasma was reliably produced and sustained by using a cylindrical resonator with the TM{sub 011} cavity mode. The applicator and the microwave cavity, which is a cylindrical resonator, are carefully designed and optimized with the time dependent finite element Maxwell equation solver. The azimuthal apertures are placed at the maximum magnetic field positions between the cavity and the applicator to maximize the coupling efficiency into the microwave plasma at a resonant frequency of 2.45 GHz. The system consists of a magnetron power supply, a circulator, a directional coupler, a three-stub tuner, a dummy load, a coaxial cavity, and a central cavity. Design and construction of the resonant structures and diagnostics of atmospheric plasma using optical experiments are discussed in various ranges of pressure and microwave input power for different types of gases.

Song, H. [Department of Electrical and Computer Engineering, University of Colorado, Colorado Springs, Colorado 80918 (United States); Hong, J. M.; Lee, K. H. [Plasma Systems and Materials (PSM) Inc., Sungnam-Si, Gyonggi-Do 190-1 (Korea, Republic of); Choi, J. J. [Department of Radio Science and Engineering, Kwangwoon University, Nowon-Gu, Seoul 447-1 (Korea, Republic of)

2008-05-15

251

Precise Solar Radiation Pressure Modeling for GRACE with Atmospheric Effects  

NASA Astrophysics Data System (ADS)

The primary objective of the GRACE (Gravity Recovery and Climate Experiment) mission is to characterize the mean and time variable components of Earth's gravity field. The two GRACE spacecraft provide high accuracy accelerometer data which is useful for a variety of other applications including thermosphere density and wind modeling and the study of variations in Earth's neutral density. Solar Radiation Pressure (SRP) modeling is important to these applications. The level of accuracy of the GRACE accelerometers and the large amount of data available from over eight years of measurement provides an opportunity to evaluate SRP modeling methods. The application of a detailed SRP modeling method developed by Professor David Vokrouhlicky of Charles University in Prague has led to very good correlation of modeling results with accelerometer data. The SRP modeling tool currently includes the effects of atmospheric refraction, atmospheric absorption, and Earth oblateness. The attached figure illustrates the influence of including atmospheric effects on the behavior of modeling results and level of correlation with accelerometer data. Sensitivity analyses more thoroughly illustrate the influences of including these effects and of varying atmosphere conditions on the behavior and quality of SRP modeling results.

Robertson, R. V.; Flury, J.; Bandikova, T.

2012-12-01

252

Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth  

NASA Astrophysics Data System (ADS)

Growth stimulation characteristics of plants seeds are investigated by an atmospheric discharge irradiation into plasma seeds. Atmospheric pressure plasma torch is consisted of alumina ceramics tube and the steel mesh electrodes wind inside and outside of the tube. When AC high voltage (8 kHz) is applied to the electrode gap, the barrier discharge plasma is produced inside the alumina ceramics tube. The barrier discharge plasma is blown outside with the gas flow in ceramics tube. Radish sprouts seeds locate at 1 cm from the torch edge. The growth stimulation was observed in the length of a stem and a root after the plasma irradiation. The stem length increases approximately 2.8 times at the cultivation time of 24 h. And the growth stimulation effect is found to be maintained for 40 h, after sowing seeds. The mechanism of the growth stimulation would be the redox reaction inside plant cells induced by oxygen radicals.

Akiyoshi, Yusuke; Hayashi, Nobuya; Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu

2011-11-01

253

Development of an Atmospheric Pressure Ionization Mass Spectrometer  

NASA Technical Reports Server (NTRS)

A commercial atmospheric pressure ionization mass spectrometer (APIMS) was purchased from EXTREL Mass Spectrometry, Inc. (Pittsburgh, PA). Our research objectives were to adapt this instrument and develop techniques for real-time determinations of the concentrations of trace species in the atmosphere. The prototype instrument is capable of making high frequency measurements with no sample preconcentrations. Isotopically labeled standards are used as an internal standard to obtain high precision and to compensate for changes in instrument sensitivity and analyte losses in the sampling manifold as described by Bandy and coworkers. The prototype instrument is capable of being deployed on NASA C130, Electra, P3, and DC8 aircraft. After purchasing and taking delivery by June 1994, we assembled the mass spectrometer, data acquisition, and manifold flow control instrumentation in electronic racks and performed tests.

1998-01-01

254

Effects of Moderate Strength Cold Air Exposure on Blood Pressure and Biochemical Indicators among Cardiovascular and Cerebrovascular Patients  

PubMed Central

The effects of cold air on cardiovascular and cerebrovascular diseases were investigated in an experimental study examining blood pressure and biochemical indicators. Zhangye, a city in Gansu Province, China, was selected as the experimental site. Health screening and blood tests were conducted, and finally, 30 cardiovascular disease patients and 40 healthy subjects were recruited. The experiment was performed during a cold event during 27–28 April 2013. Blood pressure, catecholamine, angiotensin II (ANG-II), cardiac troponin I (cTnI), muscle myoglobin (Mb) and endothefin-1 (ET-1) levels of the subjects were evaluated 1 day before, during the 2nd day of the cold exposure and 1 day after the cold air exposure. Our results suggest that cold air exposure increases blood pressure in cardiovascular disease patients and healthy subjects via the sympathetic nervous system (SNS) that is activated first and which augments ANG-II levels accelerating the release of the norepinephrine and stimulates the renin-angiotensin system (RAS). The combined effect of these factors leads to a rise in blood pressure. In addition, cold air exposure can cause significant metabolism and secretion of Mb, cTnI and ET-1 in subjects; taking the patient group as an example, ET-1 was 202.7 ng/L during the cold air exposure, increased 58 ng/L compared with before the cold air exposure, Mb and cTnI levels remained relatively high (2,219.5 ng/L and 613.2 ng/L, increased 642.1 ng/L and 306.5 ng/L compared with before the cold air exposure, respectively) 1-day after the cold exposure. This showed that cold air can cause damage to patients’ heart cells, and the damage cannot be rapidly repaired. Some of the responses related to the biochemical markers indicated that cold exposure increased cardiovascular strain and possible myocardial injury.

Zhang, Xiakun; Zhang, Shuyu; Wang, Chunling; Wang, Baojian; Guo, Pinwen

2014-01-01

255

High Frequency Variations of Arctic Ocean Bottom Pressure and Their Relation to Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

The ocean bottom pressure (OBP) was measured at the North Pole from 2005 to 2008, as part of the North Pole Environmental Observatory. OBP shows a spectral peak at a period of about 19 days, which is consistent with modeling results of OBP from the PanArctic Ice-Ocean Model Assimilation System, PIOMAS. The OBP measured in the central Beaufort Sea from 2003 to 2008 as part of the Beaufort Gyre Exploration Project shows the same spectral peak. The variations in Beaufort Sea OBP are well correlated with those at the North Pole. This signal is also detected in the sea level pressure (SLP) records from the NCEP/NCAR re-analysis for the same time as the observations of OBP. Similarly, Morison [1990] found a spectral peak at 19 days in OBP observations across the West Spitsbergen Current, in Fram Strait. Here we explore two questions: What is the source of the 19-day period atmospheric signal and how is this signal transferred to the ocean. Based on satellite altimetry, it has been shown that the inverted barometer effect applies in the Arctic Ocean at daily to weekly time-scales [Kwok, et al., 2006]. Indeed, comparison of OBP from PIOMAS, which assumes a perfect inverted barometer, with observed OBP suggests that departures from the inverted barometer response are small. The fact that the PIOMAS OBP without direct atmosphere pressure loading shows a spectral peak that is similar to observed OBP, suggests that these oscillations are wind (pressure gradient) driven rather than due to direct atmospheric loading. The basin-averaged OBP variations from PIOMAS are well correlated with the atmospheric pressure over Scandinavia. This is consistent with a correlation between southerly winds in Fram Strait and the basin-averaged OBP, with the pressure lagging the wind by 1-2 days. Through examination of atmospheric pressure data and ice-ocean model results, we investigate the hypotheses that the SLP variation is related to the passage of planetary waves across the North Atlantic, and that an Ekman slope current through Fram Strait is driving the ocean bottom pressure change. - Morison, J.H., (1990), Seasonal fluctuations in the West Spitsbergen Current estimated from bottom pressure measurements. J. Geophys. Re., 96 (C10), 18,381-18,395. - Kwok, R., G. F. Cunningham, H.J. Zwally, and D. Yi (2006), ICESat over Arctic sea ice: Interpretation of altimetric and reflectivity profiles, J. Geophys. Res., 111, C06006, doi:10.1029/2005JC003175.

Peralta Ferriz, A. C.; Morison, J.; Kwok, R.

2009-12-01

256

Vapour-liquid equilibrium studies at atmospheric to moderate pressures  

NASA Astrophysics Data System (ADS)

A study of vapour-liquid equilibria is presented together with current developments. The theory of vapour-liquid equilibria is discussed. Both experimental and prediction methods for obtaining vapour-liquid equilibria data are critically reviewed. The development of a new family of equilibrium stills to measure experimental VLE data from sub-atmosphere to 35 bar pressure is described. Existing experimental techniques are reviewed, to highlight the needs for these new apparati and their major attributes. Details are provided of how apparatus may be further improved and how computer control may be implemented. To provide a rigorous test of the apparatus the stills have been commissioned using acetic acid-water mixture at one atmosphere pressure. A Barker-type consistency test computer program, which allows for association in both phases has been applied to the data generated and clearly shows that the stills produce data of a very high quality. Two high quality data sets, for the mixture acetone- chloroform, have been generated at one atmosphere and 64.3oC. These data are used to investigate the ability of the new novel technique, based on molecular parameters, to predict VLE data for highly polar mixtures. Eight vapour-liquid equilibrium data sets have been produced for the mixture cyclohexane-ethanol mixture at one atmosphere, 2, 4, 6, 8 and 11 bar, 90.9oC and 132.8oC. These data sets have been tested for thermodynamic consistency using a Barker-type fitting package and shown to be of high quality. The data have been used to investigate the dependence of UNIQUAC parameters with temperature. The data have in addition been used to compare directly the performance of the predictive methods, Original UNIFAC, a modified version of UNIFAC and the new novel technique, based on molecular parameters developed from generalised London's potential (GLP) theory.

Russell, Paul Andrew

257

Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O2/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

Li, Shou-Zhe; Wu, Qi; Yan, Wen; Wang, Dezhen; Uhm, Han S.

2011-10-01

258

[Spectral diagnosis of plasma jet at atmospheric pressure].  

PubMed

A new approach to surface modification of materials using dielectric barrier discharge (DBD) plasma jet at atmospheric pressure is presented in the present paper. The emission spectral lines of argon plasma jet at atmospheric pressure were recorded by the grating spectrograph HR2000 and computer software. The argon plasma emission spectra, ranging from 300nm to 1000 nm, were measured at different applied voltage. Compared to air plasma emission spectra under the same circumstance, it is shown that all of the spectral lines are attributed to neutral argon atoms. The spectral lines 763.51 and 772.42 nm were chosen to estimate the electron excitation temperature. The purpose of the study is to research the relationship between the applied voltage and temperature to control the process of materials' surface modification promptly. The results show that electron excitation temperature is in the range of 0.1-0.5 eV and increases with increasing applied voltage. In the process of surface modification under the plasma jet, the infrared radiation thermometer was used to measure the material surface temperature under the plasma jet. The results show that the material surface temperature is in the range of 50-100 degrees C and it also increases with increasing applied voltage. Because the material surface was under the plasma jet and its temperature was decided by the plasma, and the material surface temperature increased with increasing the macro-temperature of plasma jet, the relationship between the surface temperature and applied voltage indicates the relationship between the macro-temperature of the plasma jet and the applied voltage approximately. The experimental results indicate that DBD plasma jet at atmospheric pressure is a new approach to improving the quality of materials' surface modification, and spectral diagnosis has proved to be a kind of workable method by choosing suitable applied voltage. PMID:19248476

Li, Chi; Tang, Xiao-liang; Qiu, Gao

2008-12-01

259

Atmospheric pressure ionization in a miniature mass spectrometer.  

PubMed

A miniature cylindrical ion trap mass spectrometer featuring an atmospheric pressure interface allowing atmospheric pressure chemical ionization and electrospray ionization is described together with its analytical performance characteristics. The vacuum system, ion optics, mass analyzer, control electronics system, and detection system have all been designed and built in-house. The design is based upon a three-stage, differentially pumped vacuum system with the instrument capable of being interfaced to many types of atmospheric pressure ionization sources. Ions are transferred through home-built ion optics, and instrument control is achieved through custom-designed electronics and LabView control software. Corona discharge ionization and electrospray ionization sources are implemented and used to allow the analysis of both gaseous- and solution-phase samples during the characterization of the instrument. An upper mass/charge limit of approximately 450 Th with unit resolution was achieved using a 2.5-mm-internal radius cylindrical ion trap as the mass analyzer. The specificity of the instrument can be increased by employing the MS/MS capabilities of the ion trap and has been demonstrated for nitrobenzene. Limits of detection for the trace analysis in air of the chemical warfare agent simulant methyl salicylate (1.24 ppb) and for nitrobenzene (629 pptr) are achieved. The dynamic range of the instrument is currently limited to approximately 2 orders of magnitude by saturation of the detection electronics. Isolation and collision-induced dissociation efficiencies in MS/MS experiments both greater than 50% are reported. Electrospray/nanospray data are presented on solutions including 100 microM (D,L)-arginine, 10 microM (-)-ephedrine, and 10 microM lomefloxacin. PMID:15859613

Laughlin, Brian C; Mulligan, Christopher C; Cooks, R Graham

2005-05-01

260

Microwave generation of stable atmospheric-pressure fireballs in air  

SciTech Connect

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.

Stephan, Karl D. [Department of Engineering and Technology, Texas State University-San Marcos, San Marcos, Texas 78666 (United States) and Process Energetics Laboratory, Dept. of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78758 (United States)

2006-11-15

261

Electrical characteristics and formation mechanism of atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

The behavior of atmospheric pressure plasma jet produced by a coplanar dielectric barrier discharge in helium in external electrostatic and magnetic field is investigated. Net negative charges in the plasma jet outside the tube were detected. The deflection of the plume in the external field was observed. The plasma jet is suggested to be formed by the electron beam from the temporal cathode which is accelerated by a longitudinal field induced by the surface charges on the dielectric tube or interface between the helium and ambient air. The helium flow is necessary for the jet formation in the surrounding air.

Liu, Lijuan; Zhang, Yu; Tian, Weijing; Meng, Ying; Ouyang, Jiting

2014-06-01

262

Electrode erosion in arc discharges at atmospheric pressure  

NASA Technical Reports Server (NTRS)

An experimental investigation was performed in an effort to measure and increase lifetime of electrodes in an arcjet thruster. The electrode erosion of various anode and cathode materials was measured after tests in an atmospheric pressure nitrogen arc discharge at powers less than 1 kW. A free-burning arc configuration and a constricted arc configuration were used to test the materials. Lanthanum hexaboride and thoriated tungsten had low cathode erosion rates while thoriated tungsten and pure tungsten had the lowest anode erosion rates of the materials tested. Anode cooling, reverse gas flow, and external magnetic fields were all found to reduce electrode mass loss.

Hardy, T. L.

1985-01-01

263

Twin injection-needle plasmas at atmospheric pressure  

SciTech Connect

Twin injection-needle plasmas at atmospheric pressure are introduced as low-temperature nonequilibrium plasma source. The plasmas with long plasma columns of about 55 cm are produced from one alternating current (ac) power supply as if each of the plasmas is a fraternal twin and shows different characteristics in plasma column length and gas temperature. The twin plasma columns are regarded as skinny rods with a uniform charge distribution, and the change of the plasma column lengths with different distances between the plasmas is compared with the change of the capacitance of the skinny rods presented as a model.

Hong, Yong Cheol; Cho, Soon Chon; Uhm, Han Sup [Department of Molecular Science and Technology, Ajou University, San 5, Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of)

2007-04-02

264

Electrode erosion in arc discharges at atmospheric pressure  

NASA Technical Reports Server (NTRS)

An experimental investigation was performed in an effort to measure and increase lifetime of electrodes in an arcjet thruster. The electrode erosion of various anode and cathode materials was measured after tests in an atmospheric pressure nitrogen arc discharge at powers less than 1 kW. A free-burning arc configuration and a constricted arc configuration were used to test the materials. Lanthanum hexboride and thoriated tungsten had low cathode erosion rates while thoriated tungsten and pure tungsten had the lowest anode erosion rates of the materials tested. Anode cooling, reverse gas flow, an external magnetic fields were all found to reduce electrode mass loss.

Hardy, T. L.

1985-01-01

265

Heat transport of nitrogen in helium atmospheric pressure microplasma  

NASA Astrophysics Data System (ADS)

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.

Xu, S. F.; Zhong, X. X.

2013-07-01

266

Electron kinetics in a microdischarge in nitrogen at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Electron kinetics during a microdischarge in nitrogen at atmospheric pressure is studied using the one-dimensional Particle-in-Cell/Monte Carlo Collisions model. It is obtained that the electron energy distribution function can be divided into three parts, namely, the non-equilibrium low-energy part, the Maxwellian function at moderate energies, and the high-energy tail. Simulation results showed that the role of the high-energy tail of electron energy distribution increases, when the distance between electrodes increases.

Levko, Dmitry

2013-12-01

267

Electron kinetics in a microdischarge in nitrogen at atmospheric pressure  

SciTech Connect

Electron kinetics during a microdischarge in nitrogen at atmospheric pressure is studied using the one-dimensional Particle-in-Cell/Monte Carlo Collisions model. It is obtained that the electron energy distribution function can be divided into three parts, namely, the non-equilibrium low-energy part, the Maxwellian function at moderate energies, and the high-energy tail. Simulation results showed that the role of the high-energy tail of electron energy distribution increases, when the distance between electrodes increases.

Levko, Dmitry [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France)] [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France)

2013-12-14

268

Carbon nanofibers synthesized by decomposition of alcohol at atmospheric pressure  

NASA Astrophysics Data System (ADS)

In the present study, we fabricated the carbon nanofibers (CNFs) by decomposition of methyl alcohol at atmospheric pressure. The CNFs were grown on Ni/Si substrates using simplified hot-filament chemical vapor deposition equipment. The deposits mainly consist of the semicrystalline CNFs, in which a few of carbon nanotubes are included. On the 30-nm-thick Ni/Si substrates, the mean length of the CNFs is 2-3 mum, and their average diameter is less than 100 nm. The as-deposited CNFs were evaluated by both scanning and transmission electron microscopes. The field-electron-emission properties of CNFs were characterized as well.

Jiang, N.; Koie, R.; Inaoka, T.; Shintani, Y.; Nishimura, K.; Hiraki, A.

2002-07-01

269

Study of a dual frequency atmospheric pressure corona plasma  

SciTech Connect

Radio frequency mixing of 2 and 13.56 MHz was investigated by performing experimental measurements on the atmospheric pressure corona plasma. As a result of the dual frequency, length, current density, and electron excitation temperature of the plasma were increased, while the gas temperature was maintained at roughly the same level when compared to the respective single frequency plasmas. Moreover, observation of time-resolved images revealed that the dual frequency plasma has a discharge mode of 2 MHz positive streamer, 2 MHz negative glow, and 13.56 MHz continuous glow.

Kim, Dan Bee; Moon, S. Y.; Jung, H.; Gweon, B.; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2010-05-15

270

Study of a dual frequency atmospheric pressure corona plasma  

NASA Astrophysics Data System (ADS)

Radio frequency mixing of 2 and 13.56 MHz was investigated by performing experimental measurements on the atmospheric pressure corona plasma. As a result of the dual frequency, length, current density, and electron excitation temperature of the plasma were increased, while the gas temperature was maintained at roughly the same level when compared to the respective single frequency plasmas. Moreover, observation of time-resolved images revealed that the dual frequency plasma has a discharge mode of 2 MHz positive streamer, 2 MHz negative glow, and 13.56 MHz continuous glow.

Kim, Dan Bee; Moon, S. Y.; Jung, H.; Gweon, B.; Choe, Wonho

2010-05-01

271

Seasonal Variations in Global Sea Level Pressure and the Total Mass of the Atmosphere  

Microsoft Academic Search

The annual cycles of sea level and surface pressures and the atmospheric pressure owing to water va- por have been analyzed in detail. Global sea level pressures undergo an annual cycle of 0.5 mbar range with a maximum in the northern winter. Global surface pressures, which represent the total mass of the atmosphere, also undergo an annual cycle of 0.5

Kevin E. Trenberth

1981-01-01

272

Growth of wheat under one tenth of the atmospheric pressure  

NASA Astrophysics Data System (ADS)

Wheat plants were grown in twin closed growth chambers under normal and reduced atmospheric pressures. For the first 22 days from sowing, the reduced pressure was maintained at 200 hPa, and at 100 hPa for the remaining 27 days until harvest. These pressures were obtained by evacuation of the chamber and adding oxygen (170 and 79 hPa respectively) and carbon dioxide (0.65 and 1.0 hPa respectively; about 2 and 3 times above the control). Eighty-seven per cent of the final dry mass was produce under 100 hPa treatment. Growth and development of wheat are not negatively affected by low pressure treatment. Compared to the control, final dry mass increased by 76 %, leaf number by 133 %, and ear number by 35 %, probably due to elevation of CO2. Shortening of shoot parts and increases in chlorophyll and proteins content are not in accordance with a predicted CO2 effect and could be attributed to the N2 removal and the subsequent alteration in gas diffusion rate.

Massimino, D.; André, M.

1999-01-01

273

Cold Atmospheric Plasma for Clinical Purposes: Promising Results in Patients and Future Applications  

NASA Astrophysics Data System (ADS)

Infected chronic wounds are both socioeconomic and medical problem. Cold atmospheric plasma (CAP) has already proven its efficacy in killing bacteria on agar plates but also the first prospective randomized controlled trial in patients. As an add-on therapy CAPs proved a highly significant decrease in bacterial load in 5 min plasma-treated wounds (34%, p < 10-6, n = 291, 36 patients) in comparison with wounds that received only standard wound care. This reduction is found in all kinds of germs, even multiresistant ones. Two minutes of plasma treatment led to a significant reduction in bacterial load as well (40%, p < 0.016, n = 70, 14 patients). The treatment is very well tolerated and no side effects occurred until now (in total more than 2,000 treatments in over 220 patients). The results of this study revealed the potential of atmospheric argon plasma treatment as a new approach to kill bacteria in terms of mutiresistancy. With the same CAP device other dermatologic diseases were treated successfully, e.g. Hailey-Hailey disease. New plasma devices using surrounding ambient air have not only greater bactericidal but also virucidal properties. These devices may herald a new era in public, personal, pet, and food hygiene, same as in decontamination. Investigations of human compatibility are promising.

Isbary, Georg

274

Atmospheric-pressure plasma decontamination/sterilization chamber  

DOEpatents

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.

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

2001-01-01

275

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

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.

Robert F. Hicks; Hans W. Herrmann

2003-12-15

276

A dc non-thermal atmospheric-pressure plasma microjet  

NASA Astrophysics Data System (ADS)

A direct current (dc), non-thermal, atmospheric-pressure plasma microjet is generated with helium/oxygen gas mixture as working gas. The electrical property is characterized as a function of the oxygen concentration and show distinctive regions of operation. Side-on images of the jet were taken to analyze the mode of operation as well as the jet length. A self-pulsed mode is observed before the transition of the discharge to normal glow mode. Optical emission spectroscopy is employed from both end-on and side-on along the jet to analyze the reactive species generated in the plasma. Line emissions from atomic oxygen (at 777.4 nm) and helium (at 706.5 nm) were studied with respect to the oxygen volume percentage in the working gas, flow rate and discharge current. Optical emission intensities of Cu and OH are found to depend heavily on the oxygen concentration in the working gas. Ozone concentration measured in a semi-confined zone in front of the plasma jet is found to be from tens to ˜120 ppm. The results presented here demonstrate potential pathways for the adjustment and tuning of various plasma parameters such as reactive species selectivity and quantities or even ultraviolet emission intensities manipulation in an atmospheric-pressure non-thermal plasma source. The possibilities of fine tuning these plasma species allows for enhanced applications in health and medical related areas.

Zhu, WeiDong; Lopez, Jose L.

2012-06-01

277

Compact atmospheric pressure plasma self-resonant drive circuits  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

278

Atmospheric oxygenation caused by a change in volcanic degassing pressure.  

PubMed

The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45?billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria and to changes in the compositions of volcanic gases, but not to the composition of erupting lavas--geochemical constraints indicate that the oxidation state of basalts and their mantle sources has remained constant since 3.5?billion years ago. Here we propose that a decrease in the average pressure of volcanic degassing changed the oxidation state of sulphur in volcanic gases, initiating the modern biogeochemical sulphur cycle and triggering atmospheric oxygenation. Using thermodynamic calculations simulating gas-melt equilibria in erupting magmas, we suggest that mostly submarine Archaean volcanoes produced gases with SO(2)/H(2)S?atmosphere. PMID:21993759

Gaillard, Fabrice; Scaillet, Bruno; Arndt, Nicholas T

2011-10-13

279

The influence of atmospheric pressure on landfill methane emissions.  

PubMed

Landfills are the largest source of anthropogenic methane (CH4) emissions to the atmosphere in the United States. However, few measurements of whole landfill CH4 emissions have been reported. Here, we present the results of a multi-season study of whole landfill CH4 emissions using atmospheric tracer methods at the Nashua, New Hampshire Municipal landfill in the northeastern United States. The measurement data include 12 individual emission tests, each test consisting of 5-8 plume measurements. Measured emissions were negatively correlated with surface atmospheric pressure and ranged from 7.3 to 26.5 m3 CH4 min(-1). A simple regression model of our results was used to calculate an annual emission rate of 8.4 x 10(6) m3 CH4 year(-1). These data, along with CH4 oxidation estimates based on emitted landfill gas isotopic characteristics and gas collection data, were used to estimate annual CH4 generation at this landfill. A reported gas collection rate of 7.1 x 10(6) m3 CH4 year(-1) and an estimated annual rate of CH4 oxidation by cover soils of 1.2 x 10(6) m3 CH4 year(-1) resulted in a calculated annual CH4 generation rate of 16.7 x 10(6) m3 CH4 year(-1). These results underscore the necessity of understanding a landfill's dynamic environment before assessing long-term emissions potential. PMID:12957154

Czepiel, P M; Shorter, J H; Mosher, B; Allwine, E; McManus, J B; Harriss, R C; Kolb, C E; Lamb, B K

2003-01-01

280

Comparative Fourier transform infrared spectroscopy study of cold-, pressure-, and heat-induced unfolding and aggregation of myoglobin.  

PubMed Central

We studied the cold unfolding of myoglobin with Fourier transform infrared spectroscopy and compared it with pressure and heat unfolding. Because protein aggregation is a phenomenon with medical as well as biotechnological implications, we were interested in both the structural changes as well as the aggregation behavior of the respective unfolded states. The cold- and pressure-induced unfolding both yield a partially unfolded state characterized by a persistent amount of secondary structure, in which a stable core of G and H helices is preserved. In this respect the cold- and pressure-unfolded states show a resemblance with an early folding intermediate of myoglobin. In contrast, the heat unfolding results in the formation of the infrared bands typical of intermolecular antiparallel beta-sheet aggregation. This implies a transformation of alpha-helix into intermolecular beta-sheet. H/2H-exchange data suggest that the helices are first unfolded and then form intermolecular beta-sheets. The pressure and cold unfolded states do not give rise to the intermolecular aggregation bands that are typical for the infrared spectra of many heat-unfolded proteins. This suggests that the pathways of the cold and pressure unfolding are substantially different from that of the heat unfolding. After return to ambient conditions the cold- or pressure-treated proteins adopt a partially refolded conformation. This aggregates at a lower temperature (32 degrees C) than the native state (74 degrees C).

Meersman, Filip; Smeller, Laszlo; Heremans, Karel

2002-01-01

281

Decolonisation of MRSA, S. aureus and E. coli by Cold-Atmospheric Plasma Using a Porcine Skin Model In Vitro  

PubMed Central

In the last twenty years new antibacterial agents approved by the U.S. FDA decreased whereas in parallel the resistance situation of multi-resistant bacteria increased. Thus, community and nosocomial acquired infections of resistant bacteria led to a decrease in the efficacy of standard therapy, prolonging treatment time and increasing healthcare costs. Therefore, the aim of this work was to demonstrate the applicability of cold atmospheric plasma for decolonisation of Gram-positive (Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus) and Gram-negative bacteria (E. coli) using an ex vivo pig skin model. Freshly excised skin samples were taken from six month old female pigs (breed: Pietrain). After application of pure bacteria on the surface of the explants these were treated with cold atmospheric plasma for up to 15 min. Two different plasma devices were evaluated. A decolonisation efficacy of 3 log10 steps was achieved already after 6 min of plasma treatment. Longer plasma treatment times achieved a killing rate of 5 log10 steps independently from the applied bacteria strains. Histological evaluations of untreated and treated skin areas upon cold atmospheric plasma treatment within 24 h showed no morphological changes as well as no significant degree of necrosis or apoptosis determined by the TUNEL-assay indicating that the porcine skin is still vital. This study demonstrates for the first time that cold atmospheric plasma is able to very efficiently kill bacteria applied to an intact skin surface using an ex vivo porcine skin model. The results emphasize the potential of cold atmospheric plasma as a new possible treatment option for decolonisation of human skin from bacteria in patients in the future without harming the surrounding tissue.

Maisch, Tim; Shimizu, Tetsuji; Li, Yang-Fang; Heinlin, Julia; Karrer, Sigrid; Morfill, Gregor; Zimmermann, Julia L.

2012-01-01

282

Measurement of viscosity of gaseous mixtures at atmospheric pressure  

NASA Technical Reports Server (NTRS)

Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model.

Singh, J. J.; Mall, G. H.; Chegini, H.

1986-01-01

283

Substrate-specific pressure-dependence of microbial sulfate reduction in deep-sea cold seep sediments of the Japan Trench  

PubMed Central

The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples.

Vossmeyer, Antje; Deusner, Christian; Kato, Chiaki; Inagaki, Fumio; Ferdelman, Timothy G.

2012-01-01

284

Effect of the pressure of sputtering atmosphere on the physical properties of amorphous aluminum oxide films  

Microsoft Academic Search

Amorphous aluminum oxide films were prepared by rf-sputtering at various values of the pressure of sputtering atmosphere, and their density, refractive index, Young's modulus and internal stress were measured. The physical properties of the present films depended on the pressure of sputtering atmosphere. The density, refractive index, and Young's modulus decreased with the pressure below about 6.5 Pa, beyond which

Y. Kijima; T. Hanada

2000-01-01

285

Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry of Carotenoids  

PubMed Central

Carotenoids are natural pigments synthesized by plants and photosynthetic microorganisms, some of which, like ?-carotene, are precursors of vitamin A, and others such as lutein and lycopene might function in the prevention of age-related macular degeneration and prostate cancer, respectively. Mass spectrometry provides high sensitivity and selectivity for the identification and quantitative analysis of carotenoids in biological samples, and previous studies have described how atmospheric pressure chemical ionization (APCI) offers distinct advantages over electrospray and fast atom bombardment for the analysis of specific carotenoids. Since APCI product ion tandem mass spectra have been reported for only a few carotenoids, a detailed investigation of twelve carotenes and xanthophylls was carried out using both positive ion and negative ion APCI tandem mass spectrometry with collision-induced dissociation. Using protonated molecules as precursor ions in positive ion mode and radical anions in negative ion mode, characteristic fragment ions were identified that may be used to distinguish between carotenoids.

van Breemen, Richard B.; Dong, Linlin; Pajkovic, Natasa D.

2011-01-01

286

Development of ac corona discharge modes at atmospheric pressure  

SciTech Connect

Corona discharges in gases exist under several distinctive forms. In this paper, a survey study has been made of ac corona discharge modes generated in some different gases fed in a wire-duct reactor with a constant rate of flowing at atmospheric pressure. The properties of different corona modes are analyzed under some condition transitions from Trichel pulses to a steady glow. In the course of the presented experimental work, numerous apparent contradictions with earlier observations necessitated further study and are given to provide more information on the physical mechanisms of the ac corona discharges. Furthermore, we have gained insight into some new technologies and applications of the environmentally friendly corona and plasma discharges.

El-Koramy, Reda Ahmed; Yehia, Ashraf; Omer, Mohamed [Department of Physics, Faculty of Science, Assiut University, 71516 Assiut (Egypt)

2011-02-15

287

Radio jet refraction in galactic atmospheres with static pressure gradients  

NASA Technical Reports Server (NTRS)

A theory based on the refraction of radio jets in the extended atmosphere of an elliptical galaxy, is proposed for double radio sources with a Z or S morphology. The model describes a collimated jet of supersonic material that bends self-consistently under the influence of external static pressure gradients, and may alternatively be seen as a continuous-jet version of the buoyancy model proposed by Gull (1973). Emphasis is placed on (1) S-shaped radio sources identified with isolated galaxies, such as 3C 293, whose radio structures should be free of distortions resulting from motion relative to a cluster medium, and (2) small-scale, galaxy-dominated rather than environment-dominated S-shaped sources such as the inner jet structure of Fornax A.

Henriksen, R. N.; Vallee, J. P.; Bridle, A. H.

1981-01-01

288

Electron Density in Atmospheric Pressure Microwave Surface Wave Discharges  

SciTech Connect

In this paper, we present results of the spectroscopic measurements of the electron density in a microwave surface wave sustained discharges in Ar and Ne at atmospheric pressure. The discharge in the form of a plasma column was generated inside a quartz tube cooled with a dielectric liquid. The microwave power delivered to the discharge via rectangular waveguide was applied in the range of 200-1500 W. In all investigations presented in this paper, the gas flow rate was relatively low (0.5 l/min), so the plasma column was generated in the form of a single filament, and the lengths of the upstream and downstream plasma columns were almost the same. The electron density in the plasma columns was determined using the method based on the Stark broadening of H{sub {beta}} spectral line, including plasma region inside the waveguide which was not investigated earlier.

Jasinski, M.; Zakrzewski, Z. [Centre for Plasma and Laser Engineering, Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-952 Gdansk (Poland); Mizeraczyk, J. [Centre for Plasma and Laser Engineering, Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-952 Gdansk (Poland); Department of Marine Electronics, Gdynia Martime University, Morska 83, 81-225 Gdynia (Poland)

2008-03-19

289

Phenomena of oscillations in atmospheric pressure direct current glow discharges  

SciTech Connect

Self-sustained oscillations in a dc glow discharge with a semiconductor layer at atmospheric pressure were investigated by means of a one-dimensional fluid model. It is found that the dc glow discharge initially becomes unstable in the subnormal glow region and gives rise to oscillations of plasma parameters. A variety of oscillations with one or more frequencies have been observed under different conditions. The discharge oscillates between the glow discharge mode and the Townsend discharge mode in the oscillations with large amplitude while operates in the subnormal glow discharge mode all the while in the oscillations with small amplitude. Fourier Transform spectra of oscillations reveal the transition mechanism between different oscillations. The effects of semiconductor conductivity on the oscillation frequency of the dominant mode, gas voltage, as well as the discharge current have also been analyzed.

Liu, Fu-cheng [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)] [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Yan, Wen; Wang, De-zhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2013-12-15

290

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy 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. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

Robert F. Hicks; Gary S. Selwyn

2001-01-09

291

Electric probe investigations of microwave generated, atmospheric pressure, plasma jets  

SciTech Connect

We examine the applicability of the Langmuir-type of characterization for atmospheric pressure plasma jets generated in a millimeter-size cavity microwave resonator at 2.45 GHz. Wide range I-V characteristics of helium, argon, nitrogen, air and oxygen are presented for different gas fluxes, distances probe-resonator, and microwave powers. A detailed analysis is performed for the fine variation in the current around the floating potential. A simplified theory specially developed for this case is presented, considering the ionic and electronic saturation currents and the floating potential. Based on this theory, we conclude that, while the charge carrier density depends on gas flow, distance to plasma source, and microwave absorbed power, the electron temperature is quite independent of these parameters. The resulting plasma parameters for helium, argon, and nitrogen are presented.

Porteanu, H. E.; Kuehn, S.; Gesche, R. [Microwave Department, Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany)

2010-07-15

292

Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma  

NASA Astrophysics Data System (ADS)

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.

Setareh, Salarieh; Davoud, Dorranian

2013-11-01

293

Development of a trielectrode plasma curtain at atmospheric pressure  

SciTech Connect

The development of a nonequilibrium, low-power, trielectrode plasma curtain at atmospheric pressure is presented. The discharge is based on the combination of an ac dielectric barrier discharge with a dc corona discharge in a three electrode system, and can be sustained for large time periods and over interelectrode air gaps up to 20 mm and with an electrode length of {approx}10 cm in the transversal direction. The discharge is composed of a train of streamers, with a repetition frequency in the range 50-200 kHz, and carrying an average current in the range 0.1-0.4 mA. The geometry of the discharge makes it appropriate for gas decontamination.

Zastawny, H.; Artana, G. [Laboratorio de Fluidodinamica, Universidad de Buenos Aires, Av. Paseo Colon 850, 1063 Buenos Aires (Argentina); Sosa, R. [Laboratorio de Fluidodinamica, Universidad de Buenos Aires, Av. Paseo Colon 850, 1063 Buenos Aires (Argentina); Instituto de Fisica del Plasma, CONICET-Dto. de Fisica, FCEN, Universidad de Buenos Aires, Ciudad. Universitaria, Pab. I, 1428 Buenos Aires (Argentina); Grondona, D.; Marquez, A.; Kelly, H. [Instituto de Fisica del Plasma, CONICET-Dto. de Fisica, FCEN, Universidad de Buenos Aires, Ciudad. Universitaria, Pab. I, 1428 Buenos Aires (Argentina)

2008-07-21

294

Thin organic films by atmospheric-pressure ion deposition.  

PubMed

Interest in thin films of functional organic materials has increased enormously in recent years because of the wide range of possible applications. Here we report an experimental setup for processing various organic materials into thin structured films under atmospheric pressure. The technique is based on an electrospray process. Microdroplets are initially formed and dried, generating ions that are extracted by electrostatic lenses. Thin structured films are then produced by the deposition of the resulting ion beam onto a moveable target. The technique offers several interesting features, including precise control of film thicknesses. We have also made experiments to investigate structured deposition, this being the first step towards the production of thin films where in all three dimensions the chemical composition can be chosen at will. This might provide a simple approach towards creating thin structured films and composites that are currently unattainable. PMID:15098026

Saf, Robert; Goriup, Marian; Steindl, Thomas; Hamedinger, Thomas E; Sandholzer, Daniel; Hayn, Gertraude

2004-05-01

295

Determination of hexabromocyclododecane by flowing atmospheric pressure afterglow mass spectrometry.  

PubMed

The first application of a flowing atmospheric-pressure afterglow ion source for mass spectrometry (FAPA-MS) for the chemical characterization and determination of hexabromocyclododecane (HBCD) is presented. The samples of technical HBCD and expanded polystyrene foam (EPS) containing HBCD as a flame retardant were prepared by dissolving the appropriate solids in dichloromethane. The ionization of HBCD was achieved with a prototype FAPA source. The ions were detected in the negative-ion mode. The ions corresponding to a deprotonated HBCD species (m/z 640.7) as well as chlorine (m/z 676.8), nitrite (m/z 687.8) and nitric (m/z 703.8) adducts were observed in the spectra. The observed isotope pattern is characteristic for a compound containing six bromine atoms. This technique is an effective approach to detect HBCD, which is efficiently ionized in a liquid phase, resulting in high detection efficiency and sensitivity. PMID:25059130

Smoluch, Marek; Silberring, Jerzy; Reszke, Edward; Kuc, Joanna; Grochowalski, Adam

2014-10-01

296

Parametric Investigations of an Atmospheric pressure Uniform Glow Discharge in helium  

NASA Astrophysics Data System (ADS)

In the cold plasma processing field, applications of the atmospheric pressure uniform glow discharge are numerous. Among them one can mention the increase of the surface energy of materials, the cleaning and etching of surfaces, and the decontamination and sterilization. The development of the glow regime at atmospheric pressure permits to avoid the technical and economical drawbacks of low pressure glow discharge systems. It also increases the efficiency of the surface treatment as compared to the corona discharge. In these conditions, a glow regime is obtained and studied in particular experimental conditions. The working gas is helium, the frequency in the range 1-20 kHz, the gap distance of some mm and the metallic electrodes are covered by a dielectric layer. The current is characterized by one peak per half cycle and is typically in the range of a few tens of mA. Since this discharge involves complex nonlinear processes and is sensitive to the variation of its parameters, detailed experimental (Ph. Decomps (1996), PhD thesis, Universite Paul Sabatier Toulouse France, No d'ordre 2538.) and numerical studies, covering wide ranges of system parameters, were required. These investigations allowed the determination of the optimal operating conditions for which the discharge remains of the glow type, and therefore induces a better surface treatment. In this paper the detailed theory ( Ben Gadri R., Rabehi A., Massines F. and Segur P. (1994), XIIth Eur. Sect. Conf. on the At. & Mol. Phy. of Ionized Gases, The Netherlands, 23-26 August, pp. 228-229.) of the one dimensional f luid model and a parametric study of the discharge characteristics are presented. A particular attention will be given to the influence of the different system parameters on the operational mode of the discharge.

Ben Gadri, Rami

1997-11-01

297

The influence of atmospheric pressure on landfill methane emissions  

SciTech Connect

Landfills are the largest source of anthropogenic methane (CH{sub 4}) emissions to the atmosphere in the United States. However, few measurements of whole landfill CH{sub 4} emissions have been reported. Here, we present the results of a multi-season study of whole landfill CH{sub 4} emissions using atmospheric tracer methods at the Nashua, New Hampshire Municipal landfill in the northeastern United States. The measurement data include 12 individual emission tests, each test consisting of 5-8 plume measurements. Measured emissions were negatively correlated with surface atmospheric pressure and ranged from 7.3 to 26.5 m{sup 3} CH{sub 4} min{sup -1}. A simple regression model of our results was used to calculate an annual emission rate of 8.4x10{sup 6} m{sup 3} CH{sub 4} year{sup -1}. These data, along with CH{sub 4} oxidation estimates based on emitted landfill gas isotopic characteristics and gas collection data, were used to estimate annual CH{sub 4} generation at this landfill. A reported gas collection rate of 7.1x10{sup 6} m{sup 3} CH{sub 4} year{sup -1} and an estimated annual rate of CH{sub 4} oxidation by cover soils of 1.2x10{sup 6} m{sup 3} CH{sub 4} year{sup -1} resulted in a calculated annual CH{sub 4} generation rate of 16.7x10{sup 6} m{sup 3} CH{sub 4} year{sup -1}. These results underscore the necessity of understanding a landfill's dynamic environment before assessing long-term emissions potential.

Czepiel, P.M.; Shorter, J.H.; Mosher, B.; Allwine, E.; McManus, J.B.; Harriss, R.C.; Kolb, C.E.; Lamb, B.K

2003-07-01

298

Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off  

NASA Technical Reports Server (NTRS)

The Cryogenics Test Laboratory (CTL) at the Kennedy Space Center (KSC) routinely utilizes cryostat test hardware to evaluate comparative and absolute thermal conductivities of a wide array of insulation systems. The test method is based on measurement of the flow rate of gas evolved due to evaporative boil-off of a cryogenic liquid. The gas flow rate typically stabilizes after a period of a couple of hours to a couple of days, depending upon the test setup. The stable flow rate value is then used to calculate the thermal conductivity for the insulation system being tested. The latest set of identical cryostats, 1,000-L spherical tanks, exhibited different behavior. On a macro level, the flow rate did stabilize after a couple of days; however the stable flow rate was oscillatory with peak to peak amplitude of up to 25 percent of the nominal value. The period of the oscillation was consistently 12 hours. The source of the oscillation has been traced to variations in atmospheric pressure due to atmospheric tides similar to oceanic tides. This paper will present analysis of this phenomenon, including a calculation that explains why other cryostats are not affected by it.

Sass, J. P.; Frontier, C. R.

2007-01-01

299

Cold atmospheric plasma in nitrogen and air generated by the hybrid plasma source  

SciTech Connect

Generation of long plumes of cold atmospheric plasma in nitrogen and air has been successfully performed by the hybrid hollow electrode activated discharge (H-HEAD) source. The source with a simple cylindrical electrode terminated by a gas nozzle combines the microwave antenna plasma with the hollow cathode plasma generated inside the gas nozzle by pulsed dc power. The H-HEAD source is capable of generating up to 10 cm long plumes in air at microwave powers below 500 W and at air flow rates as low as 100 sccm (standard cubic centimeter per minute). The corresponding flow rates in the nitrogen plasma are even less than 80 sccm. The discharges in air and nitrogen have similar shapes and are comparable with the corresponding plasma columns in argon. A comparison of the optical emission spectra of the plasma in nitrogen and air is presented. The temperatures generated on steel substrates by interaction with nitrogen and air plasma columns at different microwaves and dc powers are compared with the corresponding effects in argon plasma.

Barankova, H.; Bardos, L.; Soederstroem, D. [Angstroem Laboratory, Uppsala University, Plasma Group, Box 534, SE-751 21 Uppsala (Sweden)

2006-07-15

300

Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet  

NASA Astrophysics Data System (ADS)

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

Bayliss, D. L.; Walsh, J. L.; Shama, G.; Iza, F.; Kong, M. G.

2009-11-01

301

Modeling of inactivation of surface borne microorganisms occurring on seeds by cold atmospheric plasma (CAP)  

NASA Astrophysics Data System (ADS)

Cold Atmospheric Plasma (CAP) is a fast, low cost, simple, easy to handle technology for biological application. Our group has developed a number of different CAP devices using the microwave technology and the surface micro discharge (SMD) technology. In this study, FlatPlaSter2.0 at different time intervals (0.5 to 5 min) is used for microbial inactivation. There is a continuous demand for deactivation of microorganisms associated with raw foods/seeds without loosing their properties. This research focuses on the kinetics of CAP induced microbial inactivation of naturally growing surface microorganisms on seeds. The data were assessed for log- linear and non-log-linear models for survivor curves as a function of time. The Weibull model showed the best fitting performance of the data. No shoulder and tail was observed. The models are focused in terms of the number of log cycles reduction rather than on classical D-values with statistical measurements. The viability of seeds was not affected for CAP treatment times up to 3 min with our device. The optimum result was observed at 1 min with increased percentage of germination from 60.83% to 89.16% compared to the control. This result suggests the advantage and promising role of CAP in food industry.

Mitra, Anindita; Li, Y.-F.; Shimizu, T.; Klämpfl, Tobias; Zimmermann, J. L.; Morfill, G. E.

2012-10-01

302

Cold atmospheric air plasma sterilization against spores and other microorganisms of clinical interest.  

PubMed

Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log(10) CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D(23)(°)(C) values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma. PMID:22582068

Klämpfl, Tobias G; Isbary, Georg; Shimizu, Tetsuji; Li, Yang-Fang; Zimmermann, Julia L; Stolz, Wilhelm; Schlegel, Jürgen; Morfill, Gregor E; Schmidt, Hans-Ulrich

2012-08-01

303

Cold Atmospheric Air Plasma Sterilization against Spores and Other Microorganisms of Clinical Interest  

PubMed Central

Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log10 CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D23°C values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma.

Isbary, Georg; Shimizu, Tetsuji; Li, Yang-Fang; Zimmermann, Julia L.; Stolz, Wilhelm; Schlegel, Jurgen; Morfill, Gregor E.; Schmidt, Hans-Ulrich

2012-01-01

304

Characteristics of gusty wind disturbances and turbulent fluctuations in windy atmospheric boundary layer behind cold fronts  

NASA Astrophysics Data System (ADS)

Statistical analysis of turbulent and gusty characteristics in the atmospheric boundary layer with strong mean wind behind cold fronts has been carried out. The data used in the analysis were the multilevel ultrasonic anemometer-thermometer observations for 5 years during spring in East Asia. The results show: (1) there is systematical descending component of the basic flow in the lower part and ascending component in the upper part of the boundary layer; (2) the turbulent fluctuations (period less than 1 min) are nearly random and isotropic with weak coherency, but the gusty wind disturbances (1 min < period < 10 min) are anisotropic with rather strong coherency; (3) the kinetic energy of gusty wind disturbances and the related downward flux of momentum reach their maximum at some level below h*, where h* is the level separating the descending and ascending components of the mean flow; and (4) the turbulent kinetic energy and related downward flux of momentum increase first in the lowest layer and then decrease with height, if the fastest sampling frequency is 10 Hz, although the reason is unclear yet.

Cheng, Xueling; Zeng, Qing-Cun; Hu, Fei

2011-03-01

305

Inactivation of Salmonella enterica serovar Typhimurium on fresh produce by cold atmospheric gas plasma technology.  

PubMed

Cold atmospheric gas plasma treatment (CAP) is an alternative approach for the decontamination of fresh and minimally processed food. In this study, the effects of growth phase, growth temperature and chemical treatment regime on the inactivation of Salmonella enterica serovar Typhimurium (S. Typhimurium) by Nitrogen CAP were examined. Furthermore, the efficacy of CAP treatment for decontaminating lettuce and strawberry surfaces and potato tissue inoculated with S. Typhimurium was evaluated. It was found that the rate of inactivation of S. Typhimurium was independent of the growth phase, growth temperature and chemical treatment regime. Under optimal conditions, a 2 min treatment resulted in a 2.71 log-reduction of S. Typhimurium viability on membrane filters whereas a 15 min treatment was necessary to achieve 2.72, 1.76 and 0.94 log-reductions of viability on lettuce, strawberry and potato, respectively. We suggest that the differing efficiency of CAP treatment on the inactivation of S. Typhimurium on these different types of fresh foods is a consequence of their surface features. Scanning electron microscopy of the surface structures of contaminated samples of lettuce, strawberry and potato revealed topographical features whereby S. Typhimurium cells could be protected from the active species generated by plasma. PMID:23122497

Fernández, A; Noriega, E; Thompson, A

2013-02-01

306

Destruction of oral biofilms formed in situ on machined titanium (Ti) surfaces by cold atmospheric plasma.  

PubMed

The decontamination of implant surfaces represents the basic procedure in the management of peri-implant diseases, but it is still a challenge. The study aimed to evaluate the degradation of oral biofilms grown in situ on machined titanium (Ti) discs by cold atmospheric plasma (CAP). ~200 Ti discs were exposed to the oral cavities of five healthy human volunteers for 72 h. The resulting biofilms were divided randomly between the following treatments: CAP (which varied in mean power, treatment duration, and/or the gas mixture), and untreated and treated controls (diode laser, air-abrasion, chlorhexidine). The viability, quantity, and morphology of the biofilms were determined by live/dead staining, inoculation onto blood agar, quantification of the total protein content, and scanning electron microscopy. Exposure to CAP significantly reduced the viability and quantity of biofilms compared with the positive control treatments. The efficacy of treatment with CAP correlated with the treatment duration and plasma power. No single method achieved complete biofilm removal; however, CAP may provide an effective support to established decontamination techniques for treatment of peri-implant diseases. PMID:23574038

Idlibi, Ahmad Nour; Al-Marrawi, Fuad; Hannig, Matthias; Lehmann, Antje; Rueppell, Andre; Schindler, Axel; Jentsch, Holger; Rupf, Stefan

2013-01-01

307

Effects of pressure, cold and gloves on hand skin temperature and manual performance of divers.  

PubMed

Cold water immersion and protective gloves are associated with decreased manual performance. Although neoprene gloves slow hand cooling, there is little information on whether they provide sufficient protection when diving in cold water. Nine divers wearing three-fingered neoprene gloves and dry suits were immersed in water at 25 and 4 degrees C, at depths of 0.4 msw (101 kPa altitude adjusted) and 40 msw (497 kPa) in a hyperbaric chamber. Skin temperatures were measured at the fingers, hand, forearm, chest and head. Grip strength, tactile sensitivity and manual dexterity were measured at three time intervals. There was an exponential decay in finger and back of hand skin temperatures with exposure time in 4 degrees C water. Finger and back of hand skin temperatures were lower at 40 msw than at 0.4 msw (P < 0.05). There was no effect of pressure or temperature on grip strength. Tactile sensitivity decreased linearly with finger skin temperature at both pressures. Manual dexterity was not affected by finger skin temperature at 0.4 msw, but decreased with fall in finger skin temperature at 40 msw. Results show that neoprene gloves do not provide adequate thermal protection in 4 degrees C water and that impairment of manual performance is dependent on the type of task, depth and exposure time. PMID:18369658

Zander, Joanna; Morrison, James

2008-09-01

308

Effect of Using Liquid Feedstock in a High Pressure Cold Spray Nozzle  

NASA Astrophysics Data System (ADS)

This study investigates the effect of water injection in the high pressure chamber of a cold spray nozzle. A De Laval nozzle geometry with constant back pressure and temperature is modeled numerically using Reynolds Stress Model coupled equations. Water spray with a droplet size of 10-100 ?m is modeled using both uniform and Rosin-Rammler size distributions. The two-phase flow of gas-liquid is modeled using an unsteady discrete phase mass source with two-way coupling with the main gas flow. Upon injection, the droplets in the water spray evaporate while travelling through the nozzle due to momentum and energy exchange with the gas flow. The evaporation behavior in the presence of water content is modeled and a correlation between the initial diameter and the diameter just before the throat is obtained. As a result, the proper droplet size distribution with a fully evaporative spray can be used as a carrier of nano-particles in cold spray nozzles. Having the results, guides us to substitute the un-evaporated part of the droplet with an equal diameter agglomerate of nano-particles and find a minimum fraction of nano-particles suspended in the liquid which guarantees fully evaporative liquid spray injection.

Farvardin, E.; Stier, O.; Lüthen, V.; Dolatabadi, A.

2011-01-01

309

The combined effect of the cold pressor test and isometric exercise on heart rate and blood pressure.  

PubMed

The purpose of this study was to determine if the cold pressor test during isometric knee extension [15% of maximal voluntary contraction (MVC)] could have an additive effect on cardiovascular responses. Systolic and diastolic blood pressures, heart rate and pressure rate product were measured in eight healthy male subjects. The subjects performed the cold pressor tests and isometric leg extensions singly and in combination. The increases of systolic and diastolic blood pressure during isometric exercise were of almost the same magnitude as those during the cold pressor test. The responses of arterial blood pressure, and heart rate to a combination of the cold pressor test and isometric knee extension were greater than for each test separately. It is suggested that this additional effect of cold immersion of one hand during isometric exercise may have been due to vasoconstriction effects in the contralateral unstressed limb. In summary, the circulatory effects of the local application of cold during static exercise at 15% MVC were additive. PMID:1893909

Peikert, D; Smolander, J

1991-01-01

310

Comparison of electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization for a lipidomic analysis of Leishmania donovani.  

PubMed

A comparison of electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) for the analysis of a wide range of lipids has been performed on standard mixtures and extracts of Leishmania donovani promastigotes resistant to Amphotericin B (AmB). Calibration model, precision, limits of detection and quantification (LOD and LOQ) were assessed for each source. APPI provided the highest signal, signal-to-noise (S/N), and sensitivity for non-polar and low-polarity lipids, while ESI and APCI gave better results for the most polar ones. The linear model was valid for all lipids, except for one class with APPI, six classes with ESI, and eleven classes with APCI. LODs ranged from 0.2 to 20 ?g mL(-1) for ESI, from 0.1 to 10 ?g mL(-1) for APCI, and from 0.02 to 9.5 ?g mL(-1) for APPI. LOQs ranged from 0.2 to 61 ?g mL(-1) for ESI, from 0.4 to 31 ?g mL(-1) for APCI, and from 0.1 to 29 ?g mL(-1) for APPI. Each source provided similar lipid composition and variations in a comparison of three different L. donovani samples: miltefosine-treated, miltefosine-resistant and treated miltefosine-resistant parasites. A treated miltefosine-resistant sample was finally analyzed with each ion source in order to verify that the same lipid molecular species are detected. PMID:22560453

Imbert, Laurent; Gaudin, Mathieu; Libong, Danielle; Touboul, David; Abreu, Sonia; Loiseau, Philippe M; Laprévote, Olivier; Chaminade, Pierre

2012-06-15

311

Surface Modification by Atmospheric Pressure Plasma for Improved Bonding  

NASA Astrophysics Data System (ADS)

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 <5° to 40° over a period of 12 hours. When stored under a nitrogen purge, the water contact angle of a clean surface increased from <5° to 30° over a period of 40-60 hours. The change in contact angle resulted from the adsorption of nonanal onto the exposed surface hydroxyl groups. The rate of adsorption of nonanal under a nitrogen purged atmosphere ranged from 0.378+/-0.011 hr-1 to 0.182+/-0.008 hr -1 molecules/(cm2•s), decreasing as the fraction of hydrogen-bonded hydroxyl groups increased from 49% to 96% on the SiO 2 surface. The adsorption of the organic contaminant could be suppressed indefinitely by storing the silicon wafers in the presence of activated carbon or in a freezer at -22°C. The enhancement of adhesive bond strength and durability for carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024 was demonstrated with the atmospheric pressure helium-oxygen plasma. All surfaces studied were converted from a hydrophobic state with a water contact angle of 65° to 80° into a hydrophilic state with a water contact angle between 20° and 40° within 5 seconds of plasma exposure. X-ray photoelectron spectroscopy confirmed that the carbon atoms on the carbon-fiber/epoxy composite were oxidized, yielding 17 atom% carboxylic acid groups, 10% ketones or aldehydes and 9% alcohols. Analysis of stainless steel and aluminum by XPS illustrate oxidation of the metal surface and an increase in the concentration of hydroxyl groups in the oxide film. Following plasma activation, the total hydroxyl species concentration on stainless steel increased from 31% to 57%, while aluminum exhibited an increase from 4% to 16% hydroxyl species. Plasma activation of the surface led to an increase in bond strength of the different surfaces by up to 150% when using Cytec FM300 and FM300-2 epoxy adhesives. Wedge crack extension tests following plasma activation revealed cohesive failure percentages of 97% for carbon-fiber/epoxy composite bonded to stainless steel, and 96% for aluminum bonded to itself. The bond strength and durability of the substrates correlated with changes in the specific surface chemistry, not the wetting angle or the morphological properties of the material. This suggests that enhanced chemical bonding at the interface was responsible for the improvement in mechanical properties following plasma activation. The surface preparation of polymers and composites using atmospheric pressure plasmas is a promising technique for replacing traditional methods of surface preparation by sanding, grit blasting or peel ply. After oxygen plasma activation and joining the materials together with epoxy, one observes 100% cohesive failure within the c

Williams, Thomas Scott

312

Ocean-atmosphere interaction and the tropical climatology. Part II. Why the Pacific cold tongue is in the east  

SciTech Connect

The influence of coupled processes on the climatology of the tropical Pacific is studied in a model for the interaction of equatorial SST, the associated component of the Walker circulation, and upper-ocean dynamics. In this part, the authors show how different physical mechanisms affect the spatial pattern of the Pacific warm pool and cold tongue in this coupled climatology. When model parameters give a suitable balance between effects of upwelling and thermocline depth on sea surface temperature and for suitable atmospheric parameters, a good prototype for the observed cold-tongue configuration is produced. This is largely determined by coupled ocean-atmosphere processes within the basin, Presence of an easterly wind stress component produced by factors external to the Pacific basin can be important in setting up a cooling tendency, but this is magnified and modified by a chain of nonlinear feedbacks between trade winds and ocean dynamics affecting the SST gradient within the basin. These feedbacks determine a preferred spatial pattern that does not strongly depend on the form of the external wind stress and that tends to place the cold tongue in the east-central basin. Although robust to external influences, this pattern is sensitive to the balance of coupled processes. Parameter changes can produce warm-pool-cold-tongue patterns significantly different from observed but resembling some noted in coupled GCMs. 27 refs., 17 refs.

Dijkstra, H.A. [Univ. of Utrecht (Netherlands)] [Univ. of Utrecht (Netherlands); Neelin, J.D. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States)

1995-05-01

313

Cold Reversal on Kodiak Island, Alaska, Correlated with the European Younger Dryas by Using Variations of Atmospheric C-14 Content  

NASA Technical Reports Server (NTRS)

High-resolution AMS (accelerator-mass-spectrometer) radiocarbon dating was performed on late-glacial macrofossils in lake sediments from Kodiak Island, Alaska, and on shells in marine sediments from southwest Sweden. In both records, a dramatic drop in radiocarbon ages equivalent to a rise in the atmospheric C-14 by approximately 70%. coincides with the beginning of the cold period at 11000 yr B.P. (C-14 age). Thus our results show that a close correlation between climatic records around the globe is possible by using a global signature of changes in atmospheric C-14 content.

Hajdas, Irka; Bonani, Georges; Boden, Per; Peteet, Dorothy M.; Mann, Daniel H.

1999-01-01

314

High Pressure Cold Sprayed (HPCS) and Low Pressure Cold Sprayed (LPCS) Coatings Prepared from OFHC Cu Feedstock: Overview from Powder Characteristics to Coating Properties  

NASA Astrophysics Data System (ADS)

Cold spraying enables high quality Cu coatings to be deposited for applications where high electrical and/or thermal conductivity is needed. Fully dense Cu coatings can provide an effective corrosion barrier in specific environments. The structure of cold-sprayed Cu coatings is characterized by high deformation which imparts excellent properties. Coating properties depend on powder, the cold spray process and post treatments. First of all, powder characteristics have a strong influence on the formation of pure coatings. Secondly, cold spraying provides dense, adherent, and conductive coatings by using HPCS and LPCS. Furthermore, an addition of Al2O3 particles to the Cu powder in LPCS process significantly improves coating properties. Also, heat treatments improve electrical conductivity. This study summarizes optimal characteristics of Cu powder optimized for cold spraying, achieving high coating quality and compares properties of HPCS Cu, LPCS Cu and Cu+Al2O3 coatings prepared from the same batch of OFHC Cu powder.

Koivuluoto, Heli; Coleman, Andrew; Murray, Keith; Kearns, Martin; Vuoristo, Petri

2012-09-01

315

Atmospheric pressure ionisation multiple mass spectrometric analysis of pesticides.  

PubMed

Liquid chromatography-multiple mass spectrometry (LC-MS") has been investigated for analysis of polar pesticides in water using an ion-trap instrument and atmospheric pressure ionisation. Carbamate, triazine and phenylurea pesticides were best ionised as positive ions with atmospheric pressure chemical ionisation, while phenoxy acid herbicides, nitrophenols and bentazone yielded stronger signals as negative ions with pneumatically assisted electrospray. The ion fragmentation processes and pathways were studied in detail by MS, MS2, MS3 and MS4. All compounds were observed as their protonised or deprotonised molecular ions by MS and in the successive fragmentation by MS" the structures of typical (diagnostic) product ions were tentatively identified for each class of pesticide. Phenylureas yield an ion at m/z 72 by MS2, corresponding to O=C=N+(CH3)2. Carbamates produce [M+H-CONCH3]+ fragments by MS2 from neutral loss of methylisocyanate. Characteristic fragmentation pathways for triazine pesticides are [M+H]+-->m/z 174-->m/z 146-->m/z 110 and [M+H]+-->m/z 174-->m/z 132-->m/z 104 by MS-MS2-MS3-MS4 from cleavage of lateral chains in the triazine ring followed by ring opening. Phenoxy acid herbicides produce peculiar fragments by MS2 from loss of the acidic group possibly as the corresponding lactone. Nitrophenols are subject to loss of both *OH radical and NO groups thereby forming the correspondent phenols and quinones. The performance of the method with respect to quantitation compares favourably with traditional methods. With the ion-trap run in a time scheduled single ion monitoring mode, typical limits of detection (LODs) are in the low pg range and the repeatability standard deviations are between 3 and 15%. Assuming extraction of 1-l water samples and 1 ml final volumes the injection of 50-microl aliquots corresponds to LODs well below the requirement for the European Union water directive (EC/80/778). PMID:10497941

Baglio, D; Kotzias, D; Larsen, B R

1999-08-27

316

Timing of the Antarctic cold reversal and the atmospheric CO2 increase with respect to the Younger Dryas Event  

NASA Astrophysics Data System (ADS)

The transition from the Last Glacial to the Holocene is a key period for understanding the mechanisms of global climate change. Ice cores from the large polar ice sheets provide a wealth of information with good time resolution for this period. However, interactions between the two hemispheres can only be investigated if ice core records from Greenland and Antarctica can be synchronised accurately and reliably. The atmospheric methane concentration shows large and very fast changes during this period. These variations are well suited for a synchronisation of the age scales of ice cores from Greenland and Antarctica. Here we confirm the proposed lead of the Antarctic Cold Reversal on the Younger Dryas cold event. The Antarctic cooling precedes the Younger Dryas by at least 1.8 kyr. This suggests that northern and southern hemispheres were in anti-phase during the Younger Dryas cold event. A further result of the synchronisation is that the long-term glacial-interglacial increase of atmospheric CO2 was not interrupted during the Younger Dryas event and that atmospheric CO2 changes are not necessarily dominated by changes in the North Atlantic circulation.

Blunier, T.; Schwander, J.; Stauffer, B.; Stocker, T.; Dällenbach, A.; Indermühle, A.; Tschumi, J.; Chappellaz, J.; Raynaud, D.; Barnola, J.-M.

1997-11-01

317

Laboratory experiments of Titan tholin formed in cold plasma at various pressures: implications for nitrogen-containing polycyclic aromatic compounds in Titan haze  

NASA Astrophysics Data System (ADS)

Titan, the largest satellite of Saturn, has a thick nitrogen/methane atmosphere with a thick global organic haze. A laboratory analogue of Titan's haze, called tholin, was formed in an inductively coupled plasma from nitrogen/methane=90/10 gas mixture at various pressures ranging from 13 to 2300 Pa. Chemical and optical properties of the resulting tholin depend on the deposition pressure in cold plasma. Structural analyses by IR and UV/VIS spectroscopy, microprobe laser desorption/ionization mass spectrometry, and Raman spectroscopy suggest that larger amounts of aromatic ring structures with larger cluster size are formed at lower pressures (13 and 26 Pa) than at higher pressures (160 and 2300 Pa). Nitrogen is more likely to incorporate into carbon networks in tholins formed at lower pressures, while nitrogen is bonded as terminal groups at higher pressures. Elemental analysis reveals that the carbon/nitrogen ratio in tholins increases from 1.5-2 at lower pressures to 3 at 2300 Pa. The increase in the aromatic compounds and the decrease in C/N ratio in tholin formed at low pressures indicate the presence of the nitrogen-containing polycyclic aromatic compounds in tholin formed at low pressures. Tholin formed at high pressure (2300 Pa) consists of a polymer-like branched chain structure terminated with ?CH 3, ?NH 2, and ?C?N with few aromatic compounds. Reddish-brown tholin films formed at low pressures (13-26 Pa) shows stronger absorptions (almost 10 times larger k-value) in the UV/VIS range than the yellowish tholin films formed at high pressures (160 and 2300 Pa). The tholins formed at low pressures may be better representations of Titan's haze than those formed at high pressures, because the optical properties of tholin formed at low pressures agree well with that of Khare et al. (1984a, Icarus 60, 127-137), which have been shown to account for Titan's observed geometric albedo. Thus, the nitrogen-containing polycyclic aromatic compounds we find in tholin formed at low pressure may be present in Titan's haze. These aromatic compounds may have a significant influence on the thermal structure and complex organic chemistry in Titan's atmosphere, because they are efficient absorbers of UV radiation and efficient charge exchange intermediaries. Our results also indicate that the haze layers at various altitudes might have different chemical and optical properties.

Imanaka, Hiroshi; Khare, Bishun N.; Elsila, Jamie E.; Bakes, Emma L. O.; McKay, Christopher P.; Cruikshank, Dale P.; Sugita, Seiji; Matsui, Takafumi; Zare, Richard N.

2004-04-01

318

Power ultrasound interaction with DC atmospheric pressure electrical discharge.  

PubMed

The effect of power ultrasound application on DC hollow needle to plate atmospheric pressure electrical discharge enhanced by the flow of air through the needle electrode was studied experimentally. It was found that applying ultrasound increases discharge volume. In this volume take place plasmachemical processes, used in important ecological applications such as the production of ozone, VOC decomposition and de-NOx processes enhancement. In our experiments we used a negatively biased needle electrode as a cathode and a perpendicularly placed surface of the ultrasonic resonator--horn--as an anode. To demonstrate the effect of ultrasound waves on electrical discharge photographs of the discharge for the needle to the ultrasonic resonator at distances of 4, 6 and 8mm are shown. By varying the distance between needle and the surface of the transducer, we were able to create the node or the antinode at the region around the tip of the needle, where the ionization processes are effective. In our experimental arrangement the amplitude of acoustic pressure at antinode exceeded 10(4) Pa. The photographs reveal that the diameter of the discharge on the surface of the ultrasonic horn is increased when ultrasound is applied. The increase of discharge volume caused by the application of ultrasound can be explained as a combined effect of the change of the reduced electric field E/n (E is electric field strength and n is the neutral particles density), strong turbulence of the particles in the discharge region caused by quick changes of amplitudes of the standing ultrasonic wave and finally by the boundary layer near the ultrasonic transducer perturbations due to vibrations of the transducer surface. PMID:16793088

Bálek, Rudolf; Pekárek, Stanislav; Bartáková, Zuzana

2006-12-22

319

The application of Cold Atmospheric Plasma (CAP) for the sterilisation of spacecraft materials  

NASA Astrophysics Data System (ADS)

Plasma, oft called the fourth state of matter after solid, liquid and gas, is defined by its ionized state. Ionization can be induced by different means, such as a strong electromagnetic field applied with a microwave generator. The concentration and composition of reactive atoms and molecules produced in Cold Atmospheric Plasma (CAP) depends on the gases used, the gas flow, the power applied, the humidity level etc.. In medicine, low-temperature plasma is already used for the sterilization of surgical instruments, implants and packaging materials as plasma works at the atomic level and is able to reach all surfaces, even the interior of small hollow items like needles. Its ability to sterilise is due to the generation of biologically active bactericidal agents, such as free radicals and UV radiation. In the project PLASMA-DECON (DLR/BMWi support code 50JR1005) a prototype of a device for sterilising spacecraft material and components was built based on the surface micro-discharge (SMD) plasma technology. The produced plasma species are directed into a closed chamber which contains the parts that need to be sterilised. To test the inactivation efficiency of this new device bacterial spores were used as model organisms because in the COSPAR Planetary Protection Policy all bioburden constraints are defined with respect to the number of spores (and other heat-tolerant aerobic microorganisms). Spores from different Bacillus species and strains, i.e. wildtype strains from culture collections and isolates from spacecraft assembly cleanrooms, were dried on three different spacecraft relevant materials and exposed to CAP. The specificity, linearity, precision, and effective range of the device was investigated. From the results obtained it can be concluded that the application of CAP proved to be a suitable method for bioburden reduction / sterilisation in the frame of planetary protection measures and the design of a larger plasma device is planned in the future.

Rettberg, Petra; Barczyk, Simon; Morfill, Gregor; Thomas, Hubertus; Satoshi Shimizu, .; Shimizu, Tetsuji; Klaempfl, Tobias

2012-07-01

320

Altitude dependent Titan/fs atmospheric chemistry: UV irradiation experiments at low temperature combined with cold plasma irradiation  

NASA Astrophysics Data System (ADS)

Active organic chemistry in Titan/fs atmosphere forming organic haze and various gas species is induced by solar UV radiation and charged particle irradiations. The main available energy sources depend on altitude, so that the physical and chemical properties of the haze and the condensates of hydrocarbons and nitriles may depend on altitude. To understand Titan/fs atmospheric chemistry as a function of altitudes, we have conducted laboratory simulations using UV irradiation and/or charged particle irradiation as energy sources. We utilize GCMS for analyzing the chemical components of gas products, condensed ice mixtures, and pylorizates from tholins. First, the gas products and tholins were formed from methane-nitrogen gas mixture through cold plasma irradiation. This simulates the upper atmosphere of Titan where methane and nitrogen are dissociated by short UV and charge particle irradiations. The gas products were fractionally condensed by cold traps at several temperatures. More than 100 gas species were detected by GCMS, including saturated and unsaturated aliphatic hydrocarbons, substituted aromatics, nitriles, nitrogen heteroaromatics such as pyrrole, pyridine, pyrazine, pyrazole. Nitrogen containing compounds larger than (C+N)4 were mainly detected from ice mixture condensed at 196 K. Py-GCMS analysis of tholin revealed various alkanes, nitriles, and substituted aromatics as well as substituted pyrroles. In the lower stratosphere of Titan, various gas species diffused from the upper atmosphere may undergo further photolysis by long UV. To simulate the lower stratosphere, the gas products from cold plasma were further irradiated by long UV lights (> about 150 nm) at about 196 K and 1 mbar. The unsaturated hydrocarbons were reduced and formed the tholin materials, although the production rate was very small. Our results can be directly applied to the Huygens mission in 2005, which will measure gas compositions (GCMS) and aerosol particles (ACP-GCMS) at several altitudes in Titan/fs lower atmosphere.

Imanaka, H.; Khare, B. N.; Bakes, E. L. O.; Sekine, Y.; McKay, C. P.; Cruikshank, D. P.; McGuigan, M.; Waite, J. H.; Sacks, R.

2004-11-01

321

On the mechanism of atmospheric pressure plasma plume  

SciTech Connect

For the purpose of unveiling the parameters influencing the length of atmospheric pressure plasma plume, an over 165 cm long argon plasma plume is generated in the quartz tube attached to the nozzle of the device. Dependence of plasma length on discharge parameters such as applied voltage, frequency of power supply, and argon gas flow rate was investigated. Experimental results indicated that (a) the applied voltage plays crucial roles on plasma plume length, that is, the plasma plume length exponentially increases with the applied voltage, (b) the plasma plume length increases with frequency, more obviously when the applied voltage is higher, (c) the plasma plume length increases with argon gas flow rate, reaches its maximum at critical value of the gas flow rate, and then decreases again. An evaluation of the physical phenomena involved in streamer propagation, particularly of the energy balance, was investigated. The numerical results were qualitatively consistent with previous experimental results by successfully indicating the high velocity of ''plasma bullet'' and providing physical mechanism of energy balance determining streamer length.

Chen Longwei; Zhao Peng; Shu Xingsheng; Shen Jie; Meng Yuedong [Applied Plasma Division, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2010-08-15

322

On the mechanism of atmospheric pressure plasma plume  

NASA Astrophysics Data System (ADS)

For the purpose of unveiling the parameters influencing the length of atmospheric pressure plasma plume, an over 165 cm long argon plasma plume is generated in the quartz tube attached to the nozzle of the device. Dependence of plasma length on discharge parameters such as applied voltage, frequency of power supply, and argon gas flow rate was investigated. Experimental results indicated that (a) the applied voltage plays crucial roles on plasma plume length, that is, the plasma plume length exponentially increases with the applied voltage, (b) the plasma plume length increases with frequency, more obviously when the applied voltage is higher, (c) the plasma plume length increases with argon gas flow rate, reaches its maximum at critical value of the gas flow rate, and then decreases again. An evaluation of the physical phenomena involved in streamer propagation, particularly of the energy balance, was investigated. The numerical results were qualitatively consistent with previous experimental results by successfully indicating the high velocity of ``plasma bullet'' and providing physical mechanism of energy balance determining streamer length.

Chen, Longwei; Zhao, Peng; Shu, Xingsheng; Shen, Jie; Meng, Yuedong

2010-08-01

323

Collisional -- radiative model of helium microwave discharges at atmospheric pressure  

NASA Astrophysics Data System (ADS)

This paper presents a stationary collisional-radiative model to describe the behavior of helium microwave discharges (2.45 GHz), produced in cylindrical geometry (1 mm radius) at atmospheric pressure. The model couples the rate balance equations for the charged particles (electrons, He^+ and He2^+ ions), the He(n <= 6) excited states and the He2^* excimers, to the two-term homogeneous and stationary electron Boltzmann equation [1,2]. The latter is solved using a coherent set of electron cross sections [2], adjusted to ensure good predictions of the swarm parameters and the Townsend ionization coefficient. The model was solved for typical 5x10^14 cm-3 electron density and 2500 K gas temperature, yielding [He2^+]/[ He^+] ˜ 0.92 and [He2^*]/[ He] ˜ 3.4x10-8. Results show also that the He2^+ ions are produced mainly from the 3-body conversion of He^+ ions and lost by the corresponding reverse reaction together with diffusion and dissociative recombination. The He2^* is produced by a 3-body reaction involving the 2^3P states and by the electron-stabilized recombination of He2^+ and is lost by electron dissociation. [1] L.L. Alves et al, J. Phys. D 25, 1713 (1992). [2] T. Belmonte et al, J. Phys. D 40, 7343 (2007).

Santos, M.; Alves, L. L.; Gadonna, K.; Belmonte, T.

2011-11-01

324

Atmospheric Pressure Plasma Jet for Chem/Bio Warfare Decontamination  

NASA Astrophysics Data System (ADS)

Atmospheric Pressure Plasma Jet (APPJ) technology may provide a much needed method of CBW decontamination which, unlike traditional decon methods, is dry and nondestructive to sensitive equipment and materials. The APPJ discharge uses a high-flow feedgas consisting primarily of an inert carrier gas, such as He, and a small amount of a reactive additive, such as O2, which flows between capacitively-coupled electrodes powered at 13.56 MHz. The plasma generates highly reactive metastable and atomic species of oxygen which are then directed onto a contaminated surface. The reactive effluent of the APPJ has been shown to effectively neutralize VX nerve agent as well as simulants for anthrax and mustard blister agent. Research efforts are now being directed towards reducing He consumption and increasing the allowable stand-off distance. Recent results demonstrate that by replacing the O2 reactive additive with CO2, ozone formation is greatly reduced. This has the result of extending the lifetime of atomic oxygen by an order of magnitude or more. A recirculating APP Decon Chamber which combines heat, vacuum, forced convection and reactivity is currently being developed for enhanced decontamination of sensitive equipment. Several techniques are also being evaluated for use in an APP Decon Jet for decontamination of items which cannot be placed inside a chamber.

Herrmann, Hans W.; Henins, Ivars; Park, Jaeyoung; Selwyn, Gary S.

1999-11-01

325

Infrared polarization spectroscopy of CO 2 at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Polarisation spectroscopy (PS) was used to probe CO 2 gas concentration in a CO 2/N 2 binary mixture at atmospheric pressure and ambient temperature. The CO 2 molecules were probed by a direct laser excitation to an overtone and combination vibrational state. The tuneable narrow linewidth infrared laser radiation at 2 ?m was obtained by Raman shifting of the output from a single-longitudinal-mode pulsed alexandrite laser-system to the second Stokes component in a H 2 gas cell. Infrared polarisation spectroscopy (IRPS) and time-resolved infrared laser-induced fluorescence (IRLIF) spectra were collected. A linear dependence of the IRPS signal on the CO 2 mole fraction has been found. This indicates that the IRPS signal is only weakly affected by the molecular collisions and that the inter- and intra- molecular energy transfer processes do not strongly influence the molecular alignment at the time scale of the measurements. Thus IRPS holds great potential for quantitative instantaneous gas concentration diagnostics in general. This is especially important for molecules which do not posses an accessible optical transition such as CO, CO 2 and N 2O. In addition, an accurate experimental method to measure the extinction ratio of the IR polarisers employed in this study has been developed and applied. With its obvious merits as simplicity, easy alignment and high accuracy, the method can be generalized to all spectral regions, different polarisers and high extinction ratios.

Alwahabi, Z. T.; Li, Z. S.; Zetterberg, J.; Aldén, M.

2004-04-01

326

Atmospheric pressure chemical vapour deposition of vanadium diselenide thin films  

NASA Astrophysics Data System (ADS)

Atmospheric pressure chemical vapour deposition (APCVD) of vanadium diselenide thin films on glass substrates was achieved by reaction of [V(NMe 2) 4] and tBu 2Se. X-ray diffraction showed that the VSe 2 films were crystalline with preferential growth either along the (1 0 1) or the (1 1 0) direction. Energy-dispersive analysis by X-rays (EDAX) gave a V:Se ratio close to 1:2 for all films. The films were matt black in appearance, were adhesive, passed the Scotch tape test but could be scratched with a steel scalpel. SEM showed that the films were composed of plate-like crystallites orientated parallel to the substrate which become longer and thicker with increasing deposition temperature. Attempts to produce vanadium selenide films were also performed using tBu 2Se and two different vanadium precursors: VCl 4 and VOCl 3. Both were found to be unsuitable for producing VSe 2 from the APCVD reaction with tBu 2Se. The VSe 2 showed charge density wave transition at 110-115 K.

Boscher, Nicolas D.; Blackman, Christopher S.; Carmalt, Claire J.; Parkin, Ivan P.; Prieto, A. Garcia

2007-05-01

327

Etching materials with an atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

A plasma jet has been developed for etching materials at atmospheric pressure and between 100 and 0963-0252/7/3/005/img10C. Gas mixtures containing helium, oxygen and carbon tetrafluoride were passed between an outer, grounded electrode and a centre electrode, which was driven by 13.56 MHz radio frequency power at 50 to 500 W. At a flow rate of 0963-0252/7/3/005/img11, a stable, arc-free discharge was produced. This discharge extended out through a nozzle at the end of the electrodes, forming a plasma jet. Materials placed 0.5 cm downstream from the nozzle were etched at the following maximum rates: 0963-0252/7/3/005/img12 for Kapton (0963-0252/7/3/005/img13 and He only), 0963-0252/7/3/005/img14 for silicon dioxide, 0963-0252/7/3/005/img15 for tantalum and 0963-0252/7/3/005/img16 for tungsten. Optical emission spectroscopy was used to identify the electronically excited species inside the plasma and outside in the jet effluent.

Jeong, J. Y.; Babayan, S. E.; Tu, V. J.; Park, J.; Henins, I.; Hicks, R. F.; Selwyn, G. S.

1998-08-01

328

Growth of silicon oxynitride films by atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

Ultra-thin silicon oxynitride (SiOxNy) layers were deposited by direct interaction of plasma species formed in an atmospheric pressure plasma jet (APPJ) with a silicon wafer. APPJs have been ignited in mixtures of helium (He) together with several nitrogen-based compounds. The chemical composition of the APPJ treated silicon surfaces was analysed by ultra-high vacuum x-ray photoelectron spectroscopy (XPS). The obtained N 1s XPS spectra showed that even 5 min of APPJ treatment is sufficient to fabricate SiOxNy films with a few nanometre thickness. A Si substrate exposed to an APPJ generated in a mixture of He/NH3 resulted in the most efficient growth of SiOxNy films, indicated by the strongest N 1s XPS signal among all studied gas mixtures. Moreover, the N 1s spectra exhibited two major characteristics of chemical bonding structures attributed to nitrogen bonded to three silicon surface atoms, N–(S)3, and nitrogen bonded to two silicon surface atoms and one oxygen atom, (Si)2–N–O.

Zhang, Xueqiang; Ptasinska, Sylwia

2014-04-01

329

Using atmospheric pressure plasma treatment for treating grey cotton fabric.  

PubMed

Conventional wet treatment, desizing, scouring and bleaching, for grey cotton fabric involves the use of high water, chemical and energy consumption which may not be considered as a clean process. This study aims to investigate the efficiency of the atmospheric pressure plasma (APP) treatment on treating grey cotton fabric when compared with the conventional wet treatment. Grey cotton fabrics were treated with different combinations of plasma parameters with helium and oxygen gases and also through conventional desizing, scouring and bleaching processes in order to obtain comparable results. The results obtained from wicking and water drop tests showed that wettability of grey cotton fabrics was greatly improved after plasma treatment and yielded better results than conventional desizing and scouring. The weight reduction of plasma treated grey cotton fabrics revealed that plasma treatment can help remove sizing materials and impurities. Chemical and morphological changes in plasma treated samples were analysed by FTIR and SEM, respectively. Finally, dyeability of the plasma treated and conventional wet treated grey cotton fabrics was compared and the results showed that similar dyeing results were obtained. This can prove that plasma treatment would be another choice for treating grey cotton fabrics. PMID:24507269

Kan, Chi-Wai; Lam, Chui-Fung; Chan, Chee-Kooi; Ng, Sun-Pui

2014-02-15

330

Experimental evidence of chaotic behavior in atmospheric pressure arc discharge  

SciTech Connect

Thermal plasma technology is already playing an important role in the production of new materials, in the destruction of toxic wastes, and in the development of safer and more efficient manufacturing and material processing applications. In free burning as well as in stabilized arc columns, the inherent movement of arc root results in fluctuation in arc voltage. A full knowledge and control over the arc root dynamics can effectively lengthen the life time, drastically improve performance and reliability in arc plasma devices. In this paper, the authors experimentally investigate the fluctuating voltage signals generated from an atmospheric pressure arc discharge produced in a hollow electrode plasma torch. For the first time, analysis of these signals reveal them to exhibit chaotic behavior. The present analysis is supported with real time behavior, phase portraits, power spectra and Lyapunov exponents. Dependence of system behavior on various control parameters is also investigated. This approach is interesting in the sense that it can lead to better understanding of physics for future researches on arc plasma jets and related devices.

Ghorui, S.; Sahasrabudhe, S.N.; Murthy, P.S.S.; Das, A.K.; Venkatramani, N.

2000-02-01

331

Microchip atmospheric pressure chemical ionization source for mass spectrometry.  

PubMed

A novel microchip heated nebulizer for atmospheric pressure chemical ionization mass spectrometry is presented. Anisotropic wet etching is used to fabricate the flow channels, inlet, and nozzle on a silicon wafer. An integrated heater of aluminum is sputtered on a glass wafer. The two wafers are jointed by anodic bonding, creating a two-dimensional version of an APCI source with a sample channel in the middle and gas channels symmetrically on both sides. The ionization is initiated with an external corona-discharge needle positioned 2 mm in front of the microchip heated nebulizer. The microchip APCI source provides flow rates down to 50 nL/min, stable long-term analysis with chip lifetime of weeks, good quantitative repeatability (RSD < 10%) and linearity (r(2) > 0.995) with linear dynamic rage of at least 4 orders of magnitude, and cost-efficient manufacturing. The limit of detection (LOD) for acridine measured with microchip APCI at flow rate of 6.2 muL/min was 5 nM, corresponding to a mass flow of 0.52 fmol/s. The LOD with commercial macro-APCI at a flow rate of 1 mL/min for acridine was the same, 5 nM, corresponding to a significantly worse mass flow sensitivity (83 fmol/s) than measured with microchip APCI. The advantages of microchip APCI makes it a very attractive new microfluidic detector. PMID:15538790

Ostman, Pekka; Marttila, Seppo J; Kotiaho, Tapio; Franssila, Sami; Kostiainen, Risto

2004-11-15

332

Study of short atmospheric pressure dc glow microdischarge in air  

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

333

Water solubility in rhyolitic silicate melts at atmospheric pressure  

NASA Astrophysics Data System (ADS)

High temperature (900-1100 °C) experiments have been conducted to measure the solubility of water in a rhyolitic melt at atmospheric pressure (1 atm) and to quantify the magnitude of retrograde solubility at low pressure. Individual cores (1 cm x 1 cm) of crystal- and bubble-free rhyolitic obsidian from Hrafntinnugryggur, Krafla (Iceland) were held in a furnace at 900-1100 °C for 0.25 to 20 hours. During this time, the uniform bubble-free cores vesiculate to produce variably swollen bubble-rich run products. The volume change in each core reflects the volume of bubbles produced in each experiment and depends on the experimental temperature and the time held at that temperature. The run product volumes for isothermal experiments (e.g., 950 °C) increase non-linearly with increasing time (e.g., 0.18 cm3 at 1.5 h, 0.96 cm3 at 12.5 h) until reaching a maximum value, after which the volume does not change appreciably. We take this plateau in the isothermal volume:time curve as coinciding with the 1 atm. solubility limit for the rhyolite at this temperature. With increasing temperature, the slope and final horizontal plateaus of the volume:time curves increase such that samples from the higher temperature suites vesiculate more, as well as more rapidly (e.g., 0.85 cm3 after 0.5 hours, 1.78 cm3 after 1 hour at 1100 °C). The variations in the maximum volume of bubbles produced for each temperature constrain the retrograde solubility of water in the melt at 1 atm. Fourier transform infrared spectroscopy (FTIR) analyses of the residual water content of the glass in the starting material and in the most vesiculated sample from each temperature suite shows a decrease in the water content of the glass from an initial 0.114 wt% (? 0.013) to 0.098 wt% (? 0.010), 0.087 wt% (? 0.009), 0.093 wt% (? 0.008), 0.090 wt% (? 0.006) and 0.108 wt% (? 0.010) for 900 °C, 950 °C, 1000 °C, 1050 °C and 1100 °C respectively. This change in the solubility of water at different temperatures, though slight, produces a marked change in maximum run product porosity from 50 to 70% through the temperature series, illuminating the effect of retrograde solubility at conduit- and surface-relevant pressures. The readiness of a rhyolitic silicate melt not only to produce more bubbles at higher temperatures, but also to resorb existing bubbles during cooling has important implications for magmatic fragmentation, flow of lava, and welding processes.

Ryan, Amy; Russell, Kelly; Nichols, Alexander; Porritt, Lucy; Friedlander, Elizabeth

2014-05-01

334

Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films  

Microsoft Academic Search

Borophosphosilicate glass (BPSG) films have been grown on silicon wafers by plasma enhanced chemical vapor deposition at atmospheric pressure (AP-PECVD). Tetraethoxysilane (TEOS), triethylborate (TEB), and trimethylphosphite (TMPI) were adopted as precursors, and argon and oxygen were respectively used as the carrier and reactive gases to produce stable plasma at atmospheric pressure. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS),

Minghui Yin; Lingli Zhao; Xiangyu Xu; Shouguo Wang

2008-01-01

335

Simulations of the general circulation of the Martian atmosphere. II - Seasonal pressure variations  

NASA Astrophysics Data System (ADS)

The CO2 seasonal cycle of the Martian atmosphere and surface is simulated with a hybrid energy balance model that incorporates dynamical and radiation information from a large number of general circulation model runs. This information includes: heating due to atmospheric heat advection, the seasonally varying ratio of the surface pressure at the two Viking landing sites to the globally averaged pressure, the rate of CO2 condensation in the atmosphere, and solar heating of the atmosphere and surface. The predictions of the energy balance model are compared with the seasonal pressure variations measured at the two Viking landing sites and the springtime retreat of the seasonal polar cap boundaries. The following quantities are found to have a strong influence on the seasonal pressures at the Viking landing sites: albedo of the seasonal CO2 ice deposits, emissivity of this deposit, atmospheric heat advection, and the pressure ratio.

Pollack, J. B.; Haberle, R. M.; Murphy, J. R.; Schaeffer, J.; Lee, H.

1993-02-01

336

A Double Resonance Approach to Submillimeter\\/Terahertz Remote Sensing at Atmospheric Pressure  

Microsoft Academic Search

The remote sensing of gases in complex mixtures at atmospheric pressure is a\\u000achallenging problem and much attention has been paid to it. The most\\u000afundamental difference between this application and highly successful\\u000aastrophysical and upper atmospheric remote sensing is the line width associated\\u000awith atmospheric pressure broadening, ~ 5 GHz in all spectral regions. In this\\u000apaper, we discuss

Frank C. De Lucia; Douglas T. Petkie; Henry O. Everitt

2009-01-01

337

Microwave capillary plasmas in helium at atmospheric pressure  

NASA Astrophysics Data System (ADS)

This work uses both simulations and experiments to study helium plasmas (99.999% purity), sustained by surface-wave discharges (2.45 GHz frequency) in capillary tubes (3 mm in-radius) at atmospheric pressure. The simulations use a self-consistent homogeneous and stationary collisional–radiative model (CRM) that solves the rate balance equations for the different species present in the plasma (electrons, He+ and He_2^+ ions, He(n ? 6) excited states and He_2^* excimers) and the gas thermal balance equation, coupled with the two-term electron Boltzmann equation (including direct and stepwise inelastic and superelastic collisions as well as electron–electron collisions). The experiments use optical emission spectroscopy diagnostics to measure the electron density ne (from the H? Stark broadening), the gas temperature Tg (from the ro-vibrational transitions of OH, present at trace concentrations) and the populations of excited states in the energy region 22.7–24.2 eV, whose spectrum allows determining the excitation temperature Texc. Measurements yield ne ? (2.45 ± 1.4) × 1013 cm?3, Tg ? 1700 ± 100 K and Texc ? 2793 ± 116 K, for a ?180 ± 10 W power coupled and ?1 cm length plasma column. The model predictions at ne = 1.7 × 1013 cm?3 are in very good agreement with measurements yielding Tg = 1800 K, Texc = 2792 K (for ?30% average relative error between calculated and measured excited-state densities), and a power absorbed by the plasma per unit length of 165 W cm?1. The model results depend strongly on ne, and hence on the plasma conductivity and on the power coupled to the plasma. The coupling of a thermal module to the CRM has been shown to be crucial. Increasing the electron density leads to very high gas temperature values, which limits the variation range of (ne, Tg) as input parameters to the model.

Santos, M.; Noël, C.; Belmonte, T.; Alves, L. L.

2014-07-01

338

Abatement of perfluorinated compounds using microwave plasmas at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Microwave plasmas sustained at atmospheric pressure, for instance by electromagnetic surface waves, can be efficiently used to abate greenhouse-effect gases such as perfluorinated compounds. As a working example, we study the destruction and removal efficiency (DRE) of SF6 at concentrations ranging from 0.1% to 2.4% of the total gas flow where N2, utilized as a purge gas, is the carrier gas. O2 is added to the mixture at a fixed ratio of 1.2-1.5 times the concentration of SF6 to ensure full oxidation of the SF6 fragments, providing thereby scrubbable by-products. Fourier-transform infrared spectroscopy has been utilized for identification of the by-products and quantification of the residual concentration of SF6. Optical emission spectroscopy was employed to determine the gas temperature of the nitrogen plasma. In terms of operating parameters, the DRE is found to increase with increasing microwave power and decrease with increasing gas flow rate and discharge tube radius. Increasing the microwave power, in the case of a surface-wave discharge, or decreasing the gas flow rate increases the residence time of the molecules to be processed, hence, the observed DRE increase. In contrast, increasing the tube radius or the gas-flow rate increases the degree of radial contraction of the discharge and, therefore, the plasma-free space close to the tube wall: this comparatively colder region favors the reformation of the fragmented SF6 molecules, and enlarging it lowers the destruction rate. DRE values higher than 95% have been achieved at a microwave power of 6 kW with 2.4% SF6 in N2 flow rates up to 30 standard l/min.

Kabouzi, Y.; Moisan, M.; Rostaing, J. C.; Trassy, C.; Guérin, D.; Kéroack, D.; Zakrzewski, Z.

2003-06-01

339

Tailoring non-equilibrium atmospheric pressure plasmas for healthcare technologies  

NASA Astrophysics Data System (ADS)

Non-equilibrium plasmas operated at ambient atmospheric pressure are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. This includes the unique opportunity to deliver short-lived highly reactive species such as atomic oxygen and atomic nitrogen. Reactive oxygen and nitrogen species can initiate a wide range of reactions in biochemical systems, both therapeutic and toxic. The toxicological implications are not clear, e.g. potential risks through DNA damage. It is anticipated that interactions with biological systems will be governed through synergies between two or more species. Suitable optimized plasma sources are improbable through empirical investigations. Quantifying the power dissipation and energy transport mechanisms through the different interfaces from the plasma regime to ambient air, towards the liquid interface and associated impact on the biological system through a new regime of liquid chemistry initiated by the synergy of delivering multiple energy carrying species, is crucial. The major challenge to overcome the obstacles of quantifying energy transport and controlling power dissipation has been the severe lack of suitable plasma sources and diagnostic techniques. Diagnostics and simulations of this plasma regime are very challenging; the highly pronounced collision dominated plasma dynamics at very small dimensions requires extraordinary high resolution - simultaneously in space (microns) and time (picoseconds). Numerical simulations are equally challenging due to the inherent multi-scale character with very rapid electron collisions on the one extreme and the transport of chemically stable species characterizing completely different domains. This presentation will discuss our recent progress actively combining both advance optical diagnostics and multi-scale computer simulations.

Gans, Timo

2012-10-01

340

Atmospheric pressure dielectric barrier discharges interacting with liquid covered tissue  

NASA Astrophysics Data System (ADS)

The interaction of plasmas with liquids is of increasing importance in biomedical applications. Tissues treated by atmospheric pressure dielectric barrier discharges (DBDs) in plasma medicine are often covered by a thin layer of liquid, typically a blood serum like water with dissolved gases and proteins up to hundreds of micrometres thick. The liquid processes the plasma-produced radicals and ions prior to their reaching the tissue. In this paper, we report on a computational investigation of the interaction of DBDs in humid air with a thin water layer covering tissue. The water layer, 50–400 µm thick, contains dissolved O2aq (aq means an aqueous species) and alkane-like hydrocarbons (RHaq). In the model, the DBDs are operated with multiple pulses at 100 Hz followed by a 1 s afterglow. Gas phase reactive oxygen and nitrogen species (RONS) intersect the water-vapour saturated air above the liquid and then solvate when reaching the water. The photolysis of water by plasma-produced UV/VUV plays a significant role in the production of radicals. Without RHaq, O_{2aq}^{-} , ONOO_{aq}^{-} , NO_{3aq}^{-} and hydronium (H_{3} O_{aq}^{+} ) dominate the water ions with H_{3} O_{aq}^{+} determining the pH. The dominant RONS in the liquid are O3aq, H2O2aq, and HNOxaq. Dissolved O2aq assists the production of HNO3aq and HOONOaq during the afterglow. With RHaq, reactive oxygen species are largely consumed, leaving an R·aq (alkyl radical) to reach the tissue. These results are sensitive to the thickness of the water layer.

Tian, Wei; Kushner, Mark J.

2014-04-01

341

Atmospheric characterization of cold exoplanets using a 1.5-m coronagraphic space telescope  

NASA Astrophysics Data System (ADS)

Context. High-contrast imaging is currently the only available technique for the study of the thermodynamical and compositional properties of exoplanets in long-period orbits, comparable to the range from Venus to Jupiter. The SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) project is a coronagraphic space telescope dedicated to the spectro-polarimetric analysis of gaseous and icy giant planets as well as super-Earths at visible wavelengths. So far, studies for high-contrast imaging instruments have mainly focused on technical feasibility because of the challenging planet/star flux ratio of 10-8-10-10 required at short separations (200 mas or so) to image cold exoplanets. However, the main interest of such instruments, namely the analysis of planet atmospheric/surface properties, has remained largely unexplored. Aims: The aim of this paper is to determine which planetary properties SPICES or an equivalent direct imaging mission can measure, considering realistic reflected planet spectra and instrument limitation. Methods: We use numerical simulations of the SPICES instrument concept and theoretical planet spectra to carry out this performance study. We also define a criterion on the signal-to-noise ratio of the measured spectrum to determine under which conditions SPICES can retrieve planetary physical properties. Results: We find that the characterization of the main planetary properties (identification of molecules, effect of metallicity, presence of clouds and type of surfaces) would require a median signal-to-noise ratio of at least 30. In the case of a solar-type star ?10 pc, SPICES will be able to study Jupiters and Neptunes up to ~5 and ~2 AU respectively, because of the drastic flux decrease with separation. It would also analyze cloud and surface coverage of super-Earths of radius 2.5 Earth radii at 1 AU. Finally, we determine the potential targets in terms of planet separation, radius and distance for several stellar types. For a Sun analog, we show that SPICES could characterize Jupiters (M ? 30 Earth masses) as small as 0.5 Jupiter radii at ?2 AU up to 10 pc, and super-Earths at 1-2 AU for the handful of stars that exist within 4-5 pc. Potentially, SPICES could perform analysis of a hypothetical Earth-size planet around ? Cen A and B. However, these results depend on the planetary spectra we use, which are derived for a few planet parameters assuming a solar-type host star. Grids of model spectra are needed for a further performance analysis. Our results obtained for SPICES are also applicable to other small (1-2 m) coronagraphic space telescopes.

Maire, A.-L.; Galicher, R.; Boccaletti, A.; Baudoz, P.; Schneider, J.; Cahoy, K. L.; Stam, D. M.; Traub, W. A.

2012-05-01

342

Control of blue mold (Penicillium expansum) by fludioxonil in apples (cv Empire) under controlled atmosphere and cold storage conditions.  

PubMed

A reduced risk fungicide, fludioxonil, was tested for its efficacy against blue mold caused by thiabendazole-resistant and -sensitive Penicillium expansum (Link) Thom in apples under three storage conditions. In a co-treatment, fludioxonil and inoculum were applied together to test the protective activity of the fungicide on wounds that had been aged for 1 or 2 days. The fungicide was also tested for its curative activity in post-inoculation treatment on apples that had been inoculated for 1 or 2 days. Fludioxonil was very effective as co-treatment and as post-inoculation treatment. At a concentration of 300 mg litre(-1), fludioxonil gave complete control of post-harvest blue mold caused by the thiabendazole-resistant and -sensitive P expansum for 105 days in controlled atmosphere (CA) storage at 2 (+/-1) degrees C, for 42 days in common cold storage at 4 (+/-1) degrees C and also in a shelf-life study for 6 days at 20 (+/-1) degrees C. Comparison on the effect of fludioxonil in CA storage and common cold storage showed that higher concentrations of fungicide were needed in cold storage than in CA storage. Fludioxonil at a concentration of 450 mg litre(-1), gave 98 and 92% control of blue mold of apples in the simulated shelf-life studies after CA and common cold storages, respectively. Fludioxonil has a potential to be incorporated in the fungicide resistance management strategies for control of blue mold in apples stored for 105 days. PMID:15662721

Errampalli, Deena; Northover, John; Skog, Lisa; Brubacher, Nichole R; Collucci, Cheryl A

2005-06-01

343

Modeling the barotropic response of the Mediterranean sea level to atmospheric pressure forcing  

NASA Astrophysics Data System (ADS)

An important characteristic of the Earth's atmosphere with direct impact on the marine environmental and Earth's gravity field are the variations of atmospheric pressure as it often determines wind and weather patterns across the globe. Variations in atmospheric pressure and especially low atmospheric systems affect the values of radar altimeter sea level anomalies (SLA). This response of sea level is closed to the Inverse Barometer (IB) correction given by the altimeters within their geophysical data records. In this work, altimetric data sets from the satellite remote sensing mission of Jason-2, along with their total IB corrections acquired by the on-board altimeters, have been used for a period of forty days between October and November 2013. This period was characterized by extreme low-pressure fields over the Mediterranean Sea and especially in the area of the Ionian and Adriatic Seas and over the island of Rhodes, Greece. The Jason-2 along-track records of the SLA have been used to study both the sea level response to atmospheric pressure change over short time scales (such as ten days) and examine if the barometer correction (local and global) given by the altimeter is close to the expected response (-1 cm/mbar) of sea level to atmospheric pressure change. For the latter, atmospheric pressure data for the period under study were available from the Live Access Server (LAS) of NOAA, as well, provided at four times per day intervals in a grid format. From the LAS atmospheric pressure data, the IB effect was computed and compared with the one provided by the altimeter for its external evaluation. Finally, a regional multiple regression analysis between sea level anomalies, the LAS atmospheric pressure and wind speed components is carried out to model the barotropic response of the Mediterranean to atmospheric wind and pressure forcing.

Natsiopoulos, Dimitrios A.; Vergos, Georgios S.; Tziavos, Ilias N.

2014-05-01

344

Plasma formation in atmospheric pressure helium discharges under different background air pressures  

NASA Astrophysics Data System (ADS)

Atmospheric pressure glow discharges generated between parallel-plate electrodes in helium have been characterized using temporally resolved emission spectra. The variation of typical spectral lines over time has been analyzed. In helium with a low concentration of N2, the emission of He at 706.5 nm is dominant and appears 500 ns earlier than N2+ first negative bands, indicating low reaction rates of Penning ionization and charge transfer in the initial stage. During the decay, it is the Penning ionization caused by He metastables with a long lifetime rather than the charge transfer reaction that leads to the long decay of N2+ emissions. When helium contains a higher concentration of N2 molecules, the N2+ first negative bands become the most intense, and emissions from He, N2+, and O exhibit similar behavior as they increase. The emissions last for a shorter time under such conditions because of rapid consumption of He metastables and He2+.

Liu, Yaoge; Hao, Yanpeng; Zheng, Bin

2012-09-01

345

Non-invasive modalities of positive pressure ventilation improve the outcome of acute exacerbations in COLD patients  

Microsoft Academic Search

Objective: 1) To compare the clinical usefulness of both non-invasive pressure support ventilation (NPSV) and non-invasive intermittent positive pressure ventila- tion in assist-control (A\\/C) mode (NIPPV) in chronic ob- structive lung disease (COLD) patients with acute hyper- capnic respiratory failure: 2) to compare retrospectively the usefulness of non-invasive mechanical ventilation (NMV) with standard medical therapy alone. Design: Prospective randomized retrospective

M. Vitacca; F. Rubini; K. Foglio; S. Scalvini; S. Nava; N. Ambrosino

1993-01-01

346

Electrochemical reduction of high pressure carbon dioxide at a Cu electrode in cold methanol with CsOH supporting salt  

Microsoft Academic Search

The electrochemical reduction of high pressure CO2 at a Cu electrode in cold methanol was investigated with cesium hydroxide supporting salt. A divided H-type glass cell, which was placed in a high-pressure stainless steel vessel, was employed. The main products from CO2 by the electrochemical reduction were carbon monoxide, formic acid, methane and ethylene. The maximum current efficiency of CO

Satoshi Kaneco; Kenji Iiba; Hideyuki Katsumata; Tohru Suzuki; Kiyohisa Ohta

2007-01-01

347

Cold flow simulation of the alternate turbopump development turbine of the Space Shuttle main engine high pressure fuel turbopump  

Microsoft Academic Search

Completion of the installation at the Naval Postgraduate School of a cold-flow test facility for the turbine of the Space Shuttle Main Engine High Pressure Fuel Turbopump is reported. The article to be tested is the first stage of the Alternate Turbopump Development model designed and manufactured by Pratt & Whitney. The purpose of the facility is to enable the

Richard J. Rutkowski

1994-01-01

348

Deactivating bacteria with RF Driven Hollow Slot Microplasmas in Open Air at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

A hollow slot discharge operating in open air at atmospheric pressure has demonstrated its ability to deactivate bacterial growth on nearby surfaces exposed to the RF driven plasma. The cold plasma exits from a hollow slot with a width of 0.2 mm and variable length of 1-35 cm. An internal electrode was powered by 13.56 MHz radio-frequency power at a voltage below 200 V. External electrically grounded slots face the work piece. The plasma plume extends millimeters to centimeter beyond the hollow slot toward the work piece to be irradiated. Argon-Oxygen gas mixtures, at 33 liters per minute flow, were passed through the electrodes and the downstream plasma was employed for the process, with treatment exposure time varied from 0.06 to 0.18 seconds. Bacterial cultures were fixed to 0.22 micron cellulose filter membranes and passed under the plasma at a controlled rate at a distance of about 5-10 millimeters from the grounded slot electrode. Preliminary studies on the effectiveness of the plasma for sterilization were carried out on E. coli. Cultures were grown overnight on the membranes after exposure and the resulting colony forming units (cfu) were determined in treated and untreated groups. In the plasma treated group, a 98.2% kill rate was observed with the lowest exposure time, and increased to 99.8% when the exposure time was tripled. These studies clearly demonstrate the ability of the RF-driven hollow slot atmospheric plasma to inhibit bacterial growth on surfaces.

Yu, Zengqi; Pruden, Amy; Sharma, Ashish; Collins, George

2003-10-01

349

Final Report: "Improved Optical Diagnostic and Microwave Power Supply," an ARRA Supplement to "Instabilities in Nonthermal Atmospheric Pressure Plasma”  

SciTech Connect

This is the final report for the supplemental program “Improved Optical Diagnostic and Microwave Power Supply” which has funded the purchase of laboratory instrumentation to enhance the main DOE project, “Instabilities in Nonthermal Atmospheric Pressure Plasma.” The main program’s goals include a scientific study of the plasma physics causing large-area plasmas to become unstable at atmospheric pressure. These fundamental scientific discoveries will then allow for the design of controllable cold plasma sources capable of materials processing, including photovoltaic devices, at one atmosphere. This leads to lower costs of energy production. This final report describes only the completion of the supplement. A high-speed spectroscopic camera capable of diagnosing plasma fluctuations and instabilities on time-scales of 2 ns was specified, purchased, installed and tested at the Tufts University Plasma Laboratory. In addition, a 30 watt microwave power system capable of producing short pulses of power in the 0.8 – 4.2 GHz bands was specified, purchased, installed and tested. Scientific experiments are continuing under the funding of the main grant, but a few preliminary examples of scientific discoveries made using these items are included in this report.

Jeffrey Hopwood

2011-05-31

350

Changes in blood pressure and dipsogenic responsiveness to angiotensin II during chronic exposure of rats to cold  

SciTech Connect

To assess the role of the renin-angiotensin (RA) system in the development of cold-induced hypertension in rats, systolic blood pressure (SBP), plasma renin activity (PRA), and the dipsogenic responsiveness to s.c. administration of angiotensin II (AII) were measured weekly for 4 weeks. SBP increased significantly during the third week of exposure to cold (5C), compared to warm-adapted controls. A significant increase in SBP occurred during the third week of cold. In contrast, (PRA) increased within the first week of cold, and declined thereafter to reach the level of the control by the third week. By the fourth week, PRA decreased to a level significantly below that of control. The dipsogenic responsiveness to acute administration of AII increased significantly by the third week of cold and remained significantly elevated during the fourth week. There was a significant direct relationship between dipsogenic responsiveness to AII and SBP in the cold-treated but not the control group. There was also a significant indirect linear relationship between PRA and dipsogenic responsiveness to AII. Cold-treated rats had significant increases in urinary norepinephrine output and weights of heart, kidneys, adrenals, and brown adipose tissue. Thus, the results suggest, but do not prove, either that the elevation of blood pressure under these conditions may be induced by changes in the RA system. The results suggest further that the reduction in the drinking response to AII accompanying increases in PRA may be related to changes in the regulation of central receptors for AII.

Fregly, M.J.; Shechtman, O.; van Bergen, P.; Reeber, C.; Papanek, P.E. (Univ. of Florida, Gainesville (United States))

1991-03-11

351

Effect of Atmospheric Pressure on Wet Bulb Depression  

NASA Astrophysics Data System (ADS)

Future space exploration missions will likely operate at pressures less than 1 atm ( 100 kPa) to reduce gas leakage and structural mass, and facilitate rapid EVAs. Understanding environmental monitoring, control, and physiological responses to reduced pressures will be required to assure mission success. Wet / dry bulb psychrometers are useful devices for monitoring humidity and provide insights into cooling phenomena for wet, evaporating surfaces. To study the effects of pressure on psychrometers we conducted a series of tests in a hypobaric chamber. Chamber RH monitoring and control were based on capacitance type devices, which previous testing and manufacturer's specifications have shown to be unaffected by pressure. Test data were gathered using an Enercorp model HT-WD-A psychrometer with matched platinum RTD temperature probes positioned side-by-side with a dew point (chilled mirror) device and two capacitance RH sensors. The chamber was kept dark and measurements were taken at three RHs (30, 50, and 70) and four pressures (10, 25, 50, and 97 kPa). Results showed an increase in wet bulb depression (i.e., a drop in wet bulb temperature) for a given RH as the pressure decreased, with the largest changes occurring as pressure dropped from 25 and 10 kPa. At a dry bulb temperature of 25 C, the normal wet bulb temperature for 30 RH and 97 kPa is 15 C, but this dropped to 8 C at 10 kPa. These observations are consistent with previous reports of increased evaporation rates at reduced pressure and match recently published psychrometric models for different pressures. The results suggest that psychrometers need direct calibration at the target pressures or that pressure corrected charts are required. Moreover, for a given vapor pressure deficit, any moist surfaces, including transpiring plant leaves, will be cooler at lower pressures due to the increased evaporation rates.

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

352

Applications of tunable high energy/pressure pulsed lasers to atmospheric transmission and remote sensing  

NASA Technical Reports Server (NTRS)

Atmospheric transmission of high energy C12 O2(16) lasers were improved by pulsed high pressure operation which, due to pressure broadening of laser lines, permits tuning the laser 'off' atmospheric C12 O2(16) absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers, and for vertical transmission through the entire atmosphere. The atmospheric transmission of tuned C12 O2(16) lasers compares favorably with C12 O2(18) isotope lasers and CO lasers. The advantages of tunable, high energy, high pressure pulsed lasers over tunable diode lasers and waveguide lasers, in combining high energies with a large tuning range, are evaluated for certain applications to remote sensing of atmospheric constituents and pollutants. Pulsed operation considerably increases the signal to noise ratio without seriously affecting the high spectral resolution of signal detection obtained with laser heterodyning.

Hess, R. V.; Seals, R. K.

1974-01-01

353

Constant Altitude Flight Survey Method for Mapping Atmospheric Ambient Pressures and Systematic Radar Errors.  

National Technical Information Service (NTIS)

The flight test technique described uses controlled survey runs to determine horizontal atmospheric pressure variations and systematic altitude errors that result from space positioning measurements. The survey data can be used not only for improved air d...

T. J. Larson L. J. Ehernberger

1985-01-01

354

FORMATION OF POLYCYCLIC AROMATIC HYDROCARBONS IN AN ATMOSPHERIC PRESSURE ETHYLENE DIFFUSION FLAME. (R825412)  

EPA Science Inventory

Abstract The microstructure of an atmospheric pressure, counterflow, sooting, flat, laminar ethylene diffusion flame has been studied experimentally by withdrawing samples from within the flame using a heated quartz microprobe coupled to an online gas chromatograph/mas...

355

DURIP 98/99 Spectroscopic Diagnostics for Atmospheric Pressure Air Plasmas.  

National Technical Information Service (NTIS)

The goal of this project was to develop laser-based diagnostics employing the cavity ring-down spectroscopy (CRDS) technique for the investigation of trace quantities of molecular species in hostile environments such as atmospheric pressure air plasmas. A...

R. N. Zare

1999-01-01

356

Microbial Decontamination of Mango and Melon Surface Using a Cold Atmospheric Plasma Treatment  

Microsoft Academic Search

Summary form only given. Inactivation of micro-organism on solid surface using cold plasma has been shown effective in many cases, however there has been few report, if any, of the application of this technique to treat the skin of fruits. In this report, various spoilage micro-organisms such as: E. coli, L. monocytogenes, S. cerevisae and G. liquefaciens were deposited on

S. Perni; G. Shama; M. G. Kong

2007-01-01

357

Microstructural Evolution of 6061 Aluminum Gas-Atomized Powder and High-Pressure Cold-Sprayed Deposition  

NASA Astrophysics Data System (ADS)

Gas-atomized 6061 aluminum powder was used as feedstock for deposition using a high pressure cold-spraying process. The microstructures of the as-received powder and cold spray processed (CSP) ultrafine-grained (UFG) 6061 depositions were characterized by different electron microscopy techniques. It was found that there is segregation of solute elements at the particle grain boundaries, which is increased after cold spraying (CS). Various microstructural features were observed in both directions (parallel and perpendicular) of the CSP layer, including low-angle grain boundaries, clustered-small-cell walls, and dislocation tangle zones. The results also indicated that a combination of different recrystallization mechanisms (i.e., continuous and geometrical) may contribute to the formation of nano and UFG structures during CS.

Rokni, M. R.; Widener, C. A.; Champagne, V. R.

2014-02-01

358

Transparent conductive indium-doped zinc oxide films prepared by atmospheric pressure plasma jet  

Microsoft Academic Search

Atmospheric-pressure plasma processing has attracted much interest for industrial applications due to its low cost, high processing speed and simple system. In this study, atmospheric-pressure plasma jet technique was developed to deposit indium-doped zinc oxide films. The inorganic metal salts of zinc nitrate and indium nitrate were used as precursors for Zn ions and In ions, respectively. The effect of

Kow-Ming Chang; Sung-Hung Huang; Chin-Jyi Wu; Wei-Li Lin; Wei-Chiang Chen; Chia-Wei Chi; Je-Wei Lin; Chia-Chiang Chang

2011-01-01

359

Microwave resonance plasma source for surface modification technologies at atmospheric pressure  

Microsoft Academic Search

This paper extends the range of applications for microwave energy to create a plasma source based on the resonance phenomenon and operated at atmospheric pressure. The atmospheric-pressure process is advantageous for plasma-assisted coating deposition and plasma surface treatment. The novel Microwave Resonance Plasma Torch (MRPT) using the tunable TM 013 mode cylindrical resonant cavity and working at 2.45 GHz was

A. Taube; G. Demyashev; E. Siores

2001-01-01

360

Atmospheric pressure ionization and liquid chromatography\\/mass spectrometry—together at last  

Microsoft Academic Search

The evolution of atmospheric pressure ionization techniques which are now routinely applied as liquid chromatograph\\/mass spectrometer\\u000a (LC\\/MS) interfaces is described. Electrospray and related methods, as well as atmospheric pressure chemical ionization combined\\u000a with the heated nebulizer interface, both began as specialized ionization techniques which became much more widely accepted\\u000a when combined with tandem mass spectrometry. Today, both are widely used

Bruce A. Thomson

1998-01-01

361

Destruction of Bacillus Subtilis cells using an atmospheric-pressure capillary plasma electrode discharge  

Microsoft Academic Search

We report the results of experiments aimed at the investigation of the destruction of spore-forming bacteria, which are believed to be among the most resistant micro-organisms, using a novel atmospheric-pressure capillary plasma electrode discharge plasma. Various well-characterized cultures of Bacillus Subtilis were prepared, subjected to atmospheric-pressure plasma jets emanating from a plasma-shower reactor operated either in He or in air

N. S. Panikov; S. Paduraru; R. Crowe; P. J. Ricatto; C. Christodoulatos; K. Becker

2002-01-01

362

Atmospheric-pressure plasma cleaning of contaminated surfaces. 1998 annual progress report  

Microsoft Academic Search

'The object of this research program is to develop an atmospheric-pressure plasma jet for converting transuranic wastes (TRUs) into low-level radioactive wastes (LLWs). This plasma process will be used to efficiently decontaminate a wide range of structures and equipment. This report summarizes work after 1 year and 9 months of a 3-year project. A picture of the atmospheric-pressure plasma jet

R. F. Hicks; G. Selwyn

1998-01-01

363

Atmospheric pressure plasma for decontamination of chem\\/bio warfare agents  

Microsoft Academic Search

Summary form only given. The Atmospheric Pressure Plasma Jet (APPJ) is a unique, a capacitively-coupled RF, nonthermal, uniform discharge operating at atmospheric pressure with a high flow of He\\/O2 feedgas. The APPJ generates highly reactive atomic and metastable species of oxygen and directs them on to a contaminated surface at high velocity. This may provide a much needed method of

H. W. Henmann; G. S. Selwyn; J. Henins

1999-01-01

364

Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications  

NASA Astrophysics Data System (ADS)

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-level aerosol chemical and biological threats. Polymer solution concentration, electrospinning voltage, and deposition areal density were varied to establish the relationship of processing-structure-filtration efficiency for electrospun fiber mats. A high barrier efficiency of greater than 99.5% was achieved on electrospun fiber mats without sacrificing air permeability and pressure drop. ii) Fabrication and Characterization of Multifunctional ZnO/Nylon 6 nanofibers ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process, The electrospinning of polymer solution and electrospraying of ZnO particles were carried out simultaneously such that the ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers. The prepared ZnO/Nylon 6 nanofiber mats were tested for detoxifying characteristics against simulants of C-B agents. The results showed that ZnO/Nylon 6 functional nanofiber mats exhibited good detoxification action against paraoxon and have antibacterial efficiency over 99.99% against both the gram-negative E. coli and gram positive B. cereus bacteria. iii) Improving adhesion of electrospun nanofiber mat onto woven fabric by plasma pretreatment of substrate fabric and plasma-electrospinning hybrid process Electrospun nanofibers were deposited onto plasma-pretreated woven fabric to improve the adhesion. In addition, the plasma-electrospinning hybrid process was developed and used in which the nanofibers were subjected to in-situ plasma treatment during electrospinning. The effects of plasma treatement on substrate fabric and electrospun fibers were characterized by water contact angle test, XPS analyses. The improvement of nanofiber adhesive properties on fabric substrate was evaluated by peel test, flex resistance test and abrasion resistance test. The test results showed that the plasma treatment caused introduction of active chemical groups on substrate fabric and electrospun nanofibers. These active chemical assisted in possible cross-linking formation between nanofiber mat and substrate fabric, and this hypothesi

Vitchuli Gangadharan, Narendiran

365

Randomized placebo-controlled human pilot study of cold atmospheric argon plasma on skin graft donor sites.  

PubMed

Cold atmospheric plasma has already been shown to decrease the bacterial load in chronic wounds. However, until now it is not yet known if plasma treatment can also improve wound healing. We aimed to assess the impact of cold atmospheric argon plasma on the process of donor site healing. Forty patients with skin graft donor sites on the upper leg were enrolled in our study. The wound sites were divided into two equally sized areas that were randomly assigned to receive either plasma treatment or placebo (argon gas) for 2 minutes. Donor site healing was evaluated independently by two blinded dermatologists, who compared the wound areas with regard to reepithelialization, blood crusts, fibrin layers, and wound surroundings. From the second treatment day onwards, donor site wound areas treated with plasma (n = 34) showed significantly improved healing compared with placebo-treated areas (day 1, p = 0.25; day 2, p = 0.011; day 3, p < 0.001; day 4, p < 0.001; day 5, p = 0.004; day 6, p = 0.008; day 7, p = 0.031). Positive effects were observed in terms of improved reepithelialization and fewer fibrin layers and blood crusts, whereas wound surroundings were always normal, independent of the type of treatment. Wound infection did not occur in any of the patients, and no relevant side effects were observed. Both types of treatment were well tolerated. The mechanisms contributing to these clinically observed effects should be further investigated. PMID:23937657

Heinlin, Julia; Zimmermann, Julia L; Zeman, Florian; Bunk, Wolfram; Isbary, Georg; Landthaler, Michael; Maisch, Tim; Monetti, Roberto; Morfill, Gregor; Shimizu, Tetsuji; Steinbauer, Julia; Stolz, Wilhelm; Karrer, Sigrid

2013-01-01

366

Effect of Atmospheric Pressure on Wet Bulb Depression  

Microsoft Academic Search

Future space exploration missions will likely operate at pressures less than 1 atm ( 100 kPa) to reduce gas leakage and structural mass, and facilitate rapid EVAs. Understanding environmental monitoring, control, and physiological responses to reduced pressures will be required to assure mission success. Wet \\/ dry bulb psychrometers are useful devices for monitoring humidity and provide insights into cooling

Raymond Wheeler; Michael Stasiak; Jamie Lawson; Cara Ann Wehkamp; Mike Dixon

2008-01-01

367

Intermediate frequency atmospheric disturbances: A dynamical bridge connecting western U.S. extreme precipitation with East Asian cold surges  

NASA Astrophysics Data System (ADS)

this study, an atmospheric river (AR) detection algorithm is developed to investigate the downstream modulation of the eastern North Pacific ARs by another weather extreme, known as the East Asian cold surge (EACS), in both reanalysis data and high-resolution global model simulations. It is shown that following the peak of an EACS, atmospheric disturbances of intermediate frequency (IF; 10-30 day period) are excited downstream. This leads to the formation of a persistent cyclonic circulation anomaly over the eastern North Pacific that dramatically enhances the AR occurrence probability and the surface precipitation over the western U.S. between 30°N and 50°N. A diagnosis of the local geopotential height tendency further confirms the essential role of IF disturbances in establishing the observed persistent anomaly. This downstream modulation effect is then examined in the two simulations of the National Center for Atmospheric Research Community Climate System Model version 4 with different horizontal resolutions (T85 and T341) for the same period (1979-2005). The connection between EACS and AR is much better captured by the T341 version of the model, mainly due to a better representation of the scale interaction and the characteristics of IF atmospheric disturbances in the higher-resolution model. The findings here suggest that faithful representations of scale interaction in a global model are critical for modeling and predicting the occurrences of hydrological extremes in the western U.S. and for understanding their potential future changes.

Jiang, Tianyu; Evans, Katherine J.; Deng, Yi; Dong, Xiquan

2014-04-01

368

Measurement of the NO + O 3 Reaction Rate at Atmospheric Pressure Using Realistic Mixing Ratios  

Microsoft Academic Search

Accurate values for the rate and temperature dependence of the reaction NO + O3 ? NO2 + O2 are important in the chemical modelling of photochemical processes in the atmosphere. Previous measurements have been made at low total pressures and\\/or with very large mixing ratios relative to those observed in the atmosphere. In this study the reaction rate has been

P. C. Moonen; J. N. Cape; R. L. Storeton-West; R. McCOLM

1998-01-01

369

Rubidium filtered Thomson scattering measurement in an atmospheric pressure argon arc  

Microsoft Academic Search

High temperature, atmospheric pressure plasmas represent a significant challenge for diagnostics. The temperature is too high for physical probes, the plasmas are filamentary with dimensions too small to be resolved by microwave techniques, and the plasma luminosity and Rayleigh scattering background limit optical diagnostics. We report here the measurement of electron temperature and number density in an atmospheric arc discharge

S. H. Zaidi; Z. Tang; R. B. Miles

2001-01-01

370

Atmospheric Dispersion of Emissions Due To Leakages in Pressurized Natural Gas Ducts  

Microsoft Academic Search

A simplified approach is presented to the problem of tra nsient atmospheric dispersion of accidental releases of natural gas, originated by leakages in pressurized ducts on sea level. The model aims at estimating instantaneous high atmospheric concentration, for subsequent risk assessment analysis. In this scenario, blockage valves are used for instantaneous shutdown of tube operation, therefore isolating the harmful inventory.

F. C. M. M. Soares; O. Q. F. Araújo; J. L. Medeiros

371

Short Rise Time High Power Microwave Induced Surface Flashover at Atmospheric Pressures  

Microsoft Academic Search

High power microwave transmission is ultimately limited by window flashover at the vacuum-air dielectric boundary. While surface flashover in the presence of a vacuum has been studied in some detail, the mechanisms associated with flashover in an atmospheric environment need further investigation. For an aircraft based high power microwave system, atmospheric pressures ranging from 760 torr (sea level) to 90

Jonathan Foster; Greg Edmiston; John Krile; Herman Krompholz; Andreas Neuber

2008-01-01

372

Direct measurements of soil-gas entry into an experimental basement driven by atmospheric pressure fluctuations  

SciTech Connect

To study the importance of changes in atmospheric pressure on radon entry into houses, we have simultaneously measured the soil-gas entry into an experimental basement structure and the fluctuations in atmospheric pressure. Small amplitude ({approx}10 Pa), rapid ({approx} 20 min) fluctuations in atmospheric pressure were an important driving force for soil-gas entry because (1) the characteristic time for the propagation of a pressure disturbance in the soil gas was {approx} 2 min, and (2) the time-rate-of-change of these small fluctuations is often larger than that of the semidiurnal oscillations. An analytical model has been derived for a structure with a subslab gravel layer based on a one-dimensional solution to the transient pressure diffusion equation. This model correctly predicts the temporal response of the measure soil-gas entry into the experimental structure, but underpredicts the amplitude. 14 refs., 3 figs., 1 tab.

Robinson, A.L.; Sextro, R.G. [Lawrence Berkeley Lab., Berkeley, CA (United States)] [Lawrence Berkeley Lab., Berkeley, CA (United States)

1995-07-15

373

Atmospheric oxygenation caused by a change in volcanic degassing pressure  

Microsoft Academic Search

The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria and to changes in the compositions of

Fabrice Gaillard; Bruno Scaillet; Nicholas T. Arndt

2011-01-01

374

Decontamination of media by a gaseous discharge at atmospheric pressure  

Microsoft Academic Search

Summary form only given, as follows. The use of plasmas to decontaminate matter has recently received a lot of attention. The plasma generated by the one atmosphere glow discharge has been found to be an excellent sterilization agent. This is due to the production of free radicals which interact with proteins and acids within the cells of the microorganisms, causing

B. Pierce; C. Malott; G. S. Sayler; M. Laroussi; B. B. Glascock; B. McCurdy

1998-01-01

375

Fate of the fungicide tolylfluanid in the pear cold stored in controlled or non controlled atmosphere  

Microsoft Academic Search

Tolylfluanid (N-dichlorofluoromethylthio-N',N'-dimethyl-N-p-tolylsulfamide; Euparen M) is a contact fungicide used preventively with success against Venturia spp. on apples and pears, with a secundary activity against powdery mildews and against red spider mites. It is used against Botrytis spp. and downy mildews of strawberry, lettuce and vineyards. It is used for the protection of apples and pears during the cold storage, especially

J. Rouchaud; F. Gustin; P. Creemers; G. Goffings; M. Herregods

1991-01-01

376

Classical and quantum ordering of protons in cold solid hydrogen under megabar pressures.  

PubMed

A combination of state-of-the-art theoretical methods has been used to obtain an atomic-level picture of classical and quantum ordering of protons in cold high-pressure solid hydrogen. We focus mostly on phases II and III of hydrogen, exploring the effects of quantum nuclear motion on certain features of these phases (through a number of ab initio path integral molecular dynamics (PIMD) simulations at particular points on the phase diagram). We also examine the importance of van der Waals forces in this system by performing calculations using the optB88-vdW density functional, which accounts for non-local correlations. Our calculations reveal that the transition between phases I and II is strongly quantum in nature, resulting from a competition between anisotropic inter-molecular interactions that restrict molecular rotation and thermal plus quantum fluctuations of the nuclear positions that facilitate it. The transition from phase II to III is more classical because quantum nuclear motion plays only a secondary role and the transition is determined primarily by the underlying potential energy surface. A structure of P2(1)/c symmetry with 24 atoms in the primitive unit cell is found to be stable when anharmonic quantum nuclear vibrational motion is included at finite temperatures using the PIMD method. This structure gives a good account of the infra-red and Raman vibron frequencies of phase II. We find additional support for a C2/c structure as a strong candidate for phase III, since it remains transparent up to 300 GPa, even when quantum nuclear effects are included. Finally, we find that accounting for van der Waals forces improves the agreement between experiment and theory for the parts of the phase diagram considered, when compared to previous work which employed the widely-used Perdew-Burke-Ernzerhof exchange-correlation functional. PMID:23360786

Li, Xin-Zheng; Walker, Brent; Probert, Matthew I J; Pickard, Chris J; Needs, Richard J; Michaelides, Angelos

2013-02-27

377

Distribution of Atmospheric Pressure at Sea Level in the Lake Baikal Area.  

National Technical Information Service (NTIS)

The distribution of the average long-term atmospheric pressure over Lake Baikal, and the territory of eastern Siberia and northern Mongolia contiguous thereto, is reviewed. Use was made of average long-term pressure values from 217 stations located betwee...

V. A. Krotova L. I. Lut

1968-01-01

378

Measurements of pressure and force fields on building models in simulated atmospheric flows  

Microsoft Academic Search

Measurements and analyses of space-time structure of random pressure fields and associated area-averaged loads acting on prismatic building models in simulated atmospheric flows are presented. The objective of this study is three- fold: first, a broadening of our understanding of wind induced surface pressure fluctuations around buildings; second, gaining insight into the aerodynamics of prisms immersed in turbulent boundary layer

Ahsan Kareem

1990-01-01

379

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

PubMed

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. PMID:12481804

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

2002-01-01

380

Water cycles in closed ecological systems: effects of atmospheric pressure  

NASA Technical Reports Server (NTRS)

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.

Rygalov, Vadim Y.; Fowler, Philip A.; Metz, Joannah M.; Wheeler, Raymond M.; Bucklin, Ray A.; Sager, J. C. (Principal Investigator)

2002-01-01

381

On non-equilibrium atmospheric pressure plasma jets and plasma bullet  

NASA Astrophysics Data System (ADS)

Because of the enhanced plasma chemistry, atmospheric pressure nonequilibrium plasmas (APNPs) have been widely studied for several emerging applications such as biomedical applications. For the biomedical applications, plasma jet devices, which generate plasma in open space (surrounding air) rather than in confined discharge gaps only, have lots of advantages over the traditional dielectric barrier discharge (DBD) devices. For example, it can be used for root canal disinfection, which can't be realized by the traditional plasma device. On the other hand, currently, the working gases of most of the plasma jet devices are noble gases or the mixtures of the noble gases with small amount of O2, or air. If ambient air is used as the working gas, several serious difficulties are encountered in the plasma generation process. Amongst these are high gas temperatures and disrupting instabilities. In this presentation, firstly, a brief review of the different cold plasma jets developed to date is presented. Secondly, several different plasma jet devices developed in our lab are reported. The effects of various parameters on the plasma jets are discussed. Finally, one of the most interesting phenomena of APNP-Js, the plasma bullet is discussed and its behavior is described. References: [1] X. Lu, M. Laroussi, V. Puech, Plasma Sources Sci. Technol. 21, 034005 (2012); [2] Y. Xian, X. Lu, S. Wu, P. Chu, and Y. Pan, Appl. Phys. Lett. 100, 123702 (2012); [3] X. Pei, X. Lu, J. Liu, D. Liu, Y. Yang, K. Ostrikov, P. Chu, and Y. Pan, J. Phys. D 45, 165205 (2012).

Lu, Xinpei

2012-10-01

382

Atmospheric Pressure Oscillations Forced by Surface Waves From the 2003 Tokachi-Oki Earthquake  

NASA Astrophysics Data System (ADS)

Clear atmospheric pressure changes associated with the 2003 Tokachi-Oki Earthquake with M 8.3 were recorded by 8 microbarographs along Japan. The maximum oscillatory pressure change is about 2 Pascal with dominant period is about 15-20 second, and lasted for more than 30 minutes. Comparing the pressure change with broadband seismic records observed near or at the microbarogram, the pressure change starts at the arrival of seismic waves and reaches its maximum amplitude at the arrival of Rayleigh waves. Four microbarographs, co-located with STS-1 broadband seismographs and suffering less atmospheric wind noise, show that peaks in vertical ground velocity records correspond to the peaks of atmospheric pressure records. Similar pressure changes were observed during the largest aftershock (M 7.4). All ground motion analyzed in this paper were recorded by STS-1 broadband sensors. Spectrum analysis in the frequency domain supports that the vertical ground velocity and the pressure change has the same phase and the amplitude ratio is constant up to a period of about 50 second. The constant amplitude ratio is about (atmospheric density) times (sound velocity in the atmosphere), indicating that the surface ground in vertical ground motion compresses or inflates the air above the ground locally and low-frequency sound waves are generated. Pressure change recorded after the passage of Rayleigh waves does not well correlate with the ground velocity. Through the precise atmospheric pressure and ground motion measurement at the same sites, we witnessed the process of low-frequency sound generation by the vertical ground surface motion acted as a vibrating plate of a speaker. The radiated low-frequency sound waves propagates upward and reaches to the ionosphere with large amplitude because of the energy conservation. The ionospheric turbulence reported in the past researches were originated from this low-frequency sound at the ground surface.

Watada, S.; Nishida, K.; Sekiguchi, S.

2004-12-01

383

Electron heating in radio-frequency capacitively coupled atmospheric-pressure plasmas  

SciTech Connect

In atmospheric-pressure plasmas the main electron heating mechanism is Ohmic heating, which has distinct spatial and temporal evolutions in the {alpha} and {gamma} modes. In {gamma} discharges, ionizing avalanches in the sheaths are initiated not only by secondary electrons but also by metastable pooling reactions. In {alpha} discharges, heating takes place at the sheath edges and in contrast with low-pressure plasmas, close to 50% of the power absorbed by the electrons is absorbed at the edge of the retreating sheaths. This heating is due to a field enhancement caused by the large collisionality in atmospheric-pressure discharges.

Liu, D. W.; Iza, F.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

2008-12-29

384

Ignition during hydrogen release from high pressure into the atmosphere  

NASA Astrophysics Data System (ADS)

The first investigations concerned with a problem of hydrogen jet ignition, during outflow from a high-pressure vessel were carried out nearly 40 years ago by Wolanski and Wojcicki. The research resulted from a dramatic accident in the Chorzow Chemical Plant Azoty, where the explosion of a synthesis gas made up of a mixture composed of three moles of hydrogen per mole of nitrogen, at 300°C and 30 MPa killed four people. Initial investigation had excluded potential external ignition sources and the main aim of the research was to determine the cause of ignition. Hydrogen is currently considered as a potential fuel for various vehicles such as cars, trucks, buses, etc. Crucial safety issues are of potential concern, associated with the storage of hydrogen at a very high pressure. Indeed, the evidence obtained nearly 40 years ago shows that sudden rupture of a high-pressure hydrogen storage tank or other component can result in ignition and potentially explosion. The aim of the present research is identification of the conditions under which hydrogen ignition occurs as a result of compression and heating of the air by the shock wave generated by discharge of high-pressure hydrogen. Experiments have been conducted using a facility constructed in the Combustion Laboratory of the Institute of Heat Engineering, Warsaw University of Technology. Tests under various configurations have been performed to determine critical conditions for occurrence of high-pressure hydrogen ignition. The results show that a critical pressure exists, leading to ignition, which depends mainly on the geometric configuration of the outflow system, such as tube diameter, and on the presence of obstacles.

Oleszczak, P.; Wolanski, P.

2010-12-01

385

Wavelet filter analysis of local atmospheric pressure effects in the long-period tidal bands  

NASA Astrophysics Data System (ADS)

It is well known that local atmospheric pressure variations obviously affect the observation of short-period Earth tides, such as diurnal tides, semi-diurnal tides and ter-diurnal tides, but local atmospheric pressure effects on the long-period Earth tides have not been studied in detail. This is because the local atmospheric pressure is believed not to be sufficient for an effective pressure correction in long-period tidal bands, and there are no efficient methods to investigate local atmospheric effects in these bands. The usual tidal analysis software package, such as ETERNA, Baytap-G and VAV, cannot provide detailed pressure admittances for long-period tidal bands. We propose a wavelet method to investigate local atmospheric effects on gravity variations in long-period tidal bands. This method constructs efficient orthogonal filter bank with Daubechies wavelets of high vanishing moments. The main advantage of the wavelet filter bank is that it has excellent low frequency response and efficiently suppresses instrumental drift of superconducting gravimeters (SGs) without using any mathematical model. Applying the wavelet method to the 13-year continuous gravity observations from SG T003 in Brussels, Belgium, we filtered 12 long-period tidal groups into eight narrow frequency bands. Wavelet method demonstrates that local atmospheric pressure fluctuations are highly correlated with the noise of SG measurements in the period band 4-40 days with correlation coefficients higher than 0.95 and local atmospheric pressure variations are the main error source for the determination of the tidal parameters in these bands. We show the significant improvement of long-period tidal parameters provided by wavelet method in term of precision.

Hu, X.-G.; Liu, L. T.; Ducarme, B.; Hsu, H. T.; Sun, H.-P.

2006-11-01

386

Fullerenes and Carbon Nanotubes Formed in an Electric Arc at and Above Atmospheric Pressure  

Microsoft Academic Search

[60]Fullerene and carbon nanotubes have been obtained with an electric arc discharge in helium or argon at the pressure of 0.1–3.0 bar (i.e. from ?0.9 up to 2.0 bar above the atmospheric pressure, respectively). The yield of the process is about 10 times higher in helium with a maximum at the pressure of 0.2 bar, while in argon the maximum is observed at

J. J. Langer; S. Golczak; S. ?abi?ski; T. Gibi?ski

2004-01-01

387

Application of atmospheric pressure nonthermal plasma for the in vitro eradication of bacterial biofilms.  

PubMed

The use of atmospheric pressure nonthermal plasma represents an interesting and novel approach for the decontamination of surfaces colonized with microbial biofilms that exhibit enhanced tolerance to antimicrobial challenge. In this study, the influence of an atmospheric pressure nonthermal plasma jet, operated in a helium and oxygen gas mixture under ambient pressure, was evaluated against biofilms of Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Within < 4 min of plasma exposure, complete eradication of the two gram-positive bacterial biofilms was achieved. Although gram-negative biofilms required longer treatment time, their complete eradication was still possible with 10 min of exposure. Whilst this study provides useful proof of concept data on the use of atmospheric pressure plasmas for the eradication of bacterial biofilms in vitro, it also demonstrates the critical need for improved understanding of the mechanisms and kinetics related to such a potentially significant approach. PMID:22329678

Alkawareek, Mahmoud Y; Algwari, Qais T; Gorman, Sean P; Graham, William G; O'Connell, Deborah; Gilmore, Brendan F

2012-07-01

388

Atmospheric pressure streamer follows the turbulent argon air boundary in a MHz argon plasma jet investigated by OH-tracer PLIF spectroscopy  

NASA Astrophysics Data System (ADS)

An open question in the research of the dynamics of non-equilibrium cold atmospheric pressure plasma jets is the influence of ambient species on streamer propagation pathways. In the present work, by means of planar laser-induced fluorescence (PLIF), an atmospheric pressure argon plasma jet is investigated in a laminar and turbulent gas flow regime. The flow pattern is investigated with plasma on and plasma off. It is shown that in turbulent mode, the streamer path changes according to the flow pattern changes and the resulting changes in air abundance. From a comparison of an analytical diffusion calculation and LIF measurements, the air impurity boundary is determined. Most importantly, the origin of the streamer pathway is investigated in detail, by recording the flow pattern from OH-PLIF measurements and simultaneously measuring the streamer path by an overlay technique through emission measurements. It is shown that the streamer path is correlated to the turbulent flow pattern.

Iseni, S.; Schmidt-Bleker, A.; Winter, J.; Weltmann, K.-D.; Reuter, S.

2014-04-01

389

The Effect of Atmospheric Pressure on Rocket Thrust -- Part I.  

ERIC Educational Resources Information Center

The first of a two-part question asks: Does the total thrust of a rocket depend on the surrounding pressure? The answer to this question is provided, with accompanying diagrams of rockets. The second part of the question (and answer) are provided in v20 n7, p479, Oct 1982 of this journal. (Author/JN)

Leitner, Alfred

1982-01-01

390

Generation of large-volume, atmospheric-pressure, nonequilibrium plasmas  

Microsoft Academic Search

A review is presented of the issues associated with the generation of large-volume, high-pressure, nonequilibrium plasmas, as well as the approaches that have been developed for generating these plasmas using electrical discharges in gases. The various instabilities that have been overcome to obtained these plasmas as well as the techniques for quenching them are also reviewed. Last, recent efforts to

E. E. Kunhardt

2000-01-01

391

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

NASA Technical Reports Server (NTRS)

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.

Spanarkel, Robert; Drew, Malcolm C.

2002-01-01

392

Growth of Carnobacterium spp. from permafrost under low pressure, temperature, and anoxic atmosphere has implications for Earth microbes on Mars  

PubMed Central

The ability of terrestrial microorganisms to grow in the near-surface environment of Mars is of importance to the search for life and protection of that planet from forward contamination by human and robotic exploration. Because most water on present-day Mars is frozen in the regolith, permafrosts are considered to be terrestrial analogs of the martian subsurface environment. Six bacterial isolates were obtained from a permafrost borehole in northeastern Siberia capable of growth under conditions of low temperature (0 °C), low pressure (7 mbar), and a CO2-enriched anoxic atmosphere. By 16S ribosomal DNA analysis, all six permafrost isolates were identified as species of the genus Carnobacterium, most closely related to C. inhibens (five isolates) and C. viridans (one isolate). Quantitative growth assays demonstrated that the six permafrost isolates, as well as nine type species of Carnobacterium (C. alterfunditum, C. divergens, C. funditum, C. gallinarum, C. inhibens, C. maltaromaticum, C. mobile, C. pleistocenium, and C. viridans) were all capable of growth under cold, low-pressure, anoxic conditions, thus extending the low-pressure extreme at which life can function.

Nicholson, Wayne L.; Krivushin, Kirill; Gilichinsky, David; Schuerger, Andrew C.

2013-01-01

393

The Changing Cold Regions Network: Atmospheric, Cryospheric, Ecological and Hydrological Change in the Saskatchewan and Mackenzie River Basins, Canada (Invited)  

NASA Astrophysics Data System (ADS)

The cold interior of Northwestern Canada has one of the world's most extreme and varied climates and, as with other regions across the Arctic, is experiencing rapid environmental change. The Changing Cold Regions Network (CCRN) is a new Canadian research network devoted to addressing key challenges and globally-important issues facing the Arctic by improving the understanding of past and ongoing changes in climate, land, vegetation, and water, and predicting their future integrated responses, with a geographic focus on the Saskatchewan and Mackenzie River Basins. The network is funded for 5 years (2013-18) by the Natural Sciences and Engineering Research Council of Canada, and combines the unique expertise of 36 Canadian scientists representing 8 universities and 4 Federal government agencies, as well as 15 international researchers from the United States, China, Australia, the UK, France, and Germany. The network will also involve the World Climate Research Programme, NASA, the Canadian Space Agency, and the National Center for Atmospheric Research. CCRN will integrate existing and new experimental data with modelling and remote sensing products to understand, diagnose and predict changing land, water and climate, and their interactions and feedbacks, for Northwestern Canada's cold interior. It will use a network of world class observatories to study the detailed connections among changing climate, ecosystems and water in the permafrost regions of the Sub-arctic, the Boreal Forest, the Western Cordillera, and the Prairies. Specifically, the network will: 1. Document and evaluate observed Earth system change, including hydrological, ecological, cryospheric and atmospheric components over a range of scales from local observatories to biome and regional scales; 2. Improve understanding and diagnosis of local-scale change by developing new and integrative knowledge of Earth system processes, incorporating these processes into a suite of process-based integrative models, and using the models to better understand Earth system change; 3. Improve large-scale atmospheric and hydrological models for river basin-scale modelling and prediction to better account for the changing Earth system and its atmospheric feedbacks; and 4. Analyze and predict regional and large-scale variability and change, focusing on the governing factors for the observed trends and variability in large-scale aspects of the Earth system and their representation in current models, and the projections of regional scale effects of Earth system change on climate, land and water resources. In addition, CCRN will work collaboratively to apply and transfer the improved knowledge, modelling tools and results to government and other stakeholders, to support land and water management in the context of changing climate and economic demands. It is expected that the knowledge and tools developed through this research will benefit not only Canada, but also many other countries in cold regions that face similar challenges in the face of such uncertainty, and in particular, CCRN welcomes the opportunity for broader collaboration with the international arctic research community.

Wheater, H. S.; DeBeer, C.

2013-12-01

394

A model of the cathode region of atmospheric pressure arcs  

Microsoft Academic Search

The paper deals with calculation of parameters in the near-cathode plasma layer, on the cathode surface and in the body of a cathode in high-pressure arc discharges. These parameters can be calculated independently of the arc column if the heat flux coming from the column to the edge of the near-cathode layer does not play a decisive role in the

M. S. Benilov; A. Marotta

1995-01-01

395

Rugged, no-moving-parts windspeed and static pressure probe designs for measurements in planetary atmospheres  

NASA Technical Reports Server (NTRS)

Instruments developed for making meteorological observations under adverse conditions on Earth can be applied to systems designed for other planetary atmospheres. Specifically, a wind sensor developed for making measurements within tornados is capable of detecting induced pressure differences proportional to wind speed. Adding strain gauges to the sensor would provide wind direction. The device can be constructed in a rugged form for measuring high wind speeds in the presence of blowing dust that would clog bearings and plug passages of conventional wind speed sensors. Sensing static pressure in the lower boundary layer required development of an omnidirectional, tilt-insensitive static pressure probe. The probe provides pressure inputs to a sensor with minimum error and is inherently weather-protected. The wind sensor and static pressure probes have been used in a variety of field programs and can be adapted for use in different planetary atmospheres.

Bedard, A. J., Jr.; Nishiyama, R. T.

1993-01-01

396

Electrical discharge regimes and aerosol production in point-to-plane DC high-pressure cold plasmas  

Microsoft Academic Search

The paper deals with the production of particles by electrical discharges in point-to-grid configurations (for centimetric gaps in controlled air or nitrogen at atmospheric pressure). The original conection between discharge regimes and aerosol characteristics enables us to define the electrical parameter governing the production rate of particles and the underlying physical mechanisms which can prevail in each electrical regime. Whatever

J. P Borra; A Goldman; M Goldman; D Boulaud

1998-01-01

397

An analysis of the errors associated with the determination of atmospheric temperature from atmospheric pressure and density data  

NASA Technical Reports Server (NTRS)

A graph was developed for relating delta T/T, the relative uncertainty in atmospheric temperature T, to delta p/p, the relative uncertainty in the atmospheric pressure p, for situations, when T is derived from the slope of the pressure-height profile. A similar graph relates delta T/T to delta roh/rho, the relative uncertainty in the atmospheric density rho, for those cases when T is derived from the downward integration of the density-height profile. A comparison of these two graphs shows that for equal uncertainties in the respective basic parameters, p or rho, smaller uncertainties in the derived temperatures are associated with density-height rather than with pressure-height data. The value of delta T/T is seen to depend not only upon delta p or delta rho, and to a small extent upon the value of T or the related scale height H, but also upon the inverse of delta h, the height increment between successive observations of p or rho. In the case of pressure-height data, delta T/T is dominated by 1/delta h for all values of delta h; for density-height data, delta T/T is dominated by delta rho/rho for delta h smaller than about 5 km. In the case of T derived from density-height data, this inverse relationship between delta T/T and delta h applies only for large values of delta h, that is, for delta h 35 km. No limit exists in the fineness of usable height resolution of T which may be derived from densities, while a fine height resolution in pressure-height data leads to temperature with unacceptably large uncertainties.

Minzner, R. A.

1976-01-01

398

VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters  

NASA Astrophysics Data System (ADS)

Aims: The main goal of this research is to determine the angular size and the atmospheric structures of cool giant stars (? Oct, ? Peg, NU Pav, ? Peg, and ? Hya) and to compare them with hydrostatic stellar model atmospheres, to estimate the fundamental parameters, and to obtain a better understanding of the circumstellar environment. Methods: We conducted spectro-interferometric observations of ? Oct, ? Peg, NU Pav, and ? Peg in the near-infrared K band (2.13-2.47 ?m), and ? Hya (1.9-2.47 ?m) with the VLTI/AMBER instrument at medium spectral resolution (~1500). To obtain the fundamental parameters, we compared our data with hydrostatic atmosphere models (PHOENIX). Results: We estimated the Rosseland angular diameters of ? Oct, ? Peg, NU Pav, ? Peg, and ? Hya to be 11.66±1.50 mas, 16.87±1.00 mas, 13.03±1.75 mas, 6.31±0.35 mas, and 3.78±0.65 mas, respectively. Together with distances and bolometric fluxes (obtained from the literature), we estimated radii, effective temperatures, and luminosities of our targets. In the ? Peg visibility, we observed a molecular layer of CO with a size similar to that modeled with PHOENIX. However, there is an additional slope in absorption starting around 2.3 ?m. This slope is possibly due to a shell of H2O that is not modeled with PHOENIX (the size of the layer increases to about 5% with respect to the near-continuum level). The visibility of ? Peg shows a low increase in the CO bands, compatible with the modeling of the PHOENIX model. The visibility data of ? Oct, NU Pav, and ? Hya show no increase in molecular bands. Conclusions: The spectra and visibilities predicted by the PHOENIX atmospheres agree with the spectra and the visibilities observed in our stars (except for ? Peg). This indicates that the opacity of the molecular bands is adequately included in the model, and the atmospheres of our targets have an extension similar to the modeled atmospheres. The atmosphere of ? Peg is more extended than that predicted by the model. The role of pulsations, if relevant in other cases and unmodeled by PHOENIX, therefore seems negligible for the atmospheric structures of our sample. The targets are located close to the red limits of the evolutionary tracks of the STAREVOL model, corresponding to masses between 1 M? and 3 M?. The STAREVOL model fits the position of our stars in the Hertzsprung-Russell (HR) diagram better than the Ekström model does. STAREVOL includes thermohaline mixing, unlike the Ekström model, and complements the latter for intermediate-mass stars. Based on observations made with the VLT Interferometer (VLTI) at Paranal Observatory under programme ID 089.D-0801.Figures 2-4 are available in electronic form at http://www.aanda.org

Arroyo-Torres, B.; Martí-Vidal, I.; Marcaide, J. M.; Wittkowski, M.; Guirado, J. C.; Hauschildt, P. H.; Quirrenbach, A.; Fabregat, J.

2014-06-01

399

A rule-of-thumb for atmospheric density and pressure versus altitude  

NASA Astrophysics Data System (ADS)

Order-of-magnitude values for the density and pressure of the Earth's atmosphere are readily obtained for altitudes up to 160 km by means of a simple rule-of-thumb. The results, while not precise, are good enough for rough calculations when your favorite atmospheric table is not at hand.The rule-of-thumb is atmospheric massdensity, number-density, and pressure all decrease by approximately a factor of 10 for every 10-mile increase in altitude up to an altitude of 100 miles. (This is one of the few cases in which working with English units is advantageous.) Interpolation in 5-mile increments is obtained by using a factor of three decrease in atmospheric parameters for every 5-mile increase in altitude.

Dessler, A. J.

400

Asteroid entry in Venusian atmosphere: Pressure and density fields effect on crater formation  

NASA Technical Reports Server (NTRS)

The objectives are to look at time scales of overpressure compared to cratering and to determine: what are the transient pressure and density due to atmospheric entry; do shock waves evacuate ambient gas; do transient atmospheric disturbances 'settle down' during cratering; can the pressure/density field be approximated as quasi-static; how does disturbance scale with impactor size; and what is the role of atmospheric thickness. The general approach is to perform inexpensive exploratory calculations, perform experiments to validate code and observe crater growth, and to follow up with more realistic coupling calculations. This viewgraph presentation presents progress made with the objective to obtain useful scaling relationships for crater formation when atmospheric effects are important.

Schmidt, Robert

1995-01-01

401

Using the Transportable Array to Explore the Relationship between Atmospheric Pressure and Ground Displacement  

NASA Astrophysics Data System (ADS)

We use data from the Transportable Array (TA) component of EarthScope’s USArray to study the relationship between atmospheric pressure and ground tilt at long periods. Recent upgrades to the TA station hardware include an environmental monitoring sensor package for state of health monitoring. The environmental sensors provide observations of vault temperature, relative humidity, and atmospheric pressure. As the TA rolls eastward each new station is being equipped with the environmental sensor package. Over 250 TA stations in the central plains are already transmitting data from these new sensors, providing an unprecedented new dataset of co-located seismic and atmospheric pressure observations. Previous studies have observed that variations in local atmospheric pressure are strongly correlated to horizontal ground displacement at periods of several hundred seconds or more as a result of atmospheric pressure-induced tilt. Tilt is a major source of noise on long-period horizontal seismic recordings. For individual seismographic stations it has been demonstrated that the atmospheric pressure recordings can be used as an effective means of reducing long-period horizontal seismic noise by correcting for the pressure-induced tilt. To-date, observations of the pressure-tilt correlation have been made at only a limited number of widely separated and highly unique sites, making it difficult to separate systematic versus local effects. The TA now provides the means to make co-located pressure and displacement observations for identically constructed seismic station vaults deployed in a grid with 70 km separation between sites - allowing the TA to make multiple, uniform samples of the same large-scale pressure systems. We have computed the coherence between the pressure and displacement time series at each TA station that is equipped with the environmental monitoring sensors. The coherence is computed for discrete time windows, with results accumulated over the course of multiple months of observations. We will present results of this analysis as a means of exploring the systematics of the relationship between pressure and ground tilt as a function of time and space, giving particular attention to separating regional- and local-scale effects.

Woodward, R.; Busby, R. W.; Hafner, K.

2010-12-01

402

2.45 GHz microwave-excited atmospheric pressure air microplasmas based on microstrip technology  

NASA Astrophysics Data System (ADS)

A plasma system based on microstrip technology was developed for the generation of atmospheric pressure microplasmas. A discharge gap was placed between the striplines and the ground plane on the transverse cross section in the direction of microwave propagation. This microstrip structure permits the concentration of electric fields at the discharge gap, which is confirmed by a computer simulation using the three-dimensional simulation code based on the finite-difference time-domain method, and can produce atmospheric pressure plasmas even in air. The microplasmas were sustained in the discharge gap (width: 0.2 mm, length: 6 mm) at a microwave power of 1 W. The experimentally measured rotational temperature of nitrogen molecules was 800 K, indicating these plasmas to be nonthermal plasmas. This plasma system will provide a portable microplasma system utilizing a small semiconductor microwave source and a large-scale atmospheric pressure nonthermal plasma using the array configuration.

Kim, Jaeho; Terashima, Kazuo

2005-05-01

403

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

404

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

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

405

Ozone generation using atmospheric pressure glow discharge in air  

NASA Astrophysics Data System (ADS)

This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltag