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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

Three distinct modes in a cold atmospheric pressure plasma jet  

Microsoft Academic Search

Cold atmospheric pressure helium plasma jets are increasingly used in many processing applications, due to a distinct combination of their inherent plasma stability with excellent reaction chemistry often enhanced downstream. Despite their widespread usage, it remains largely unknown whether cold atmospheric plasma jets maintain similar characteristics from breakdown to arcing or whether they possess different operating modes. In addition to

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

2010-01-01

3

Interactions of cold atmospheric pressure plasma jets with plasmid DNA  

Microsoft Academic Search

Summary form only given. Cold atmospheric pressure plasmas offer a unique environment for treatments of soft materials, including bio-materials and living tissue. Single plasma devices can be as small as micro-meters allowing very precise treatments reducing damage to surrounding healthy living cells. It is essential to correlate direct plasma parameters with effects on bio-materials. There are various energy carrying species

D. O'Connell; L. Cox; W. Hyland; S. McMahon; B. Graham; T. Gans; F. Currell

2010-01-01

4

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

5

Cold atmospheric pressure air plasma jet for medical applications  

NASA Astrophysics Data System (ADS)

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.; Mohamed, A.-A. H.; Price, R. O.; Swanson, R. J.; Bowman, A.; Chiavarini, R. L.; Stacey, M.; Schoenbach, K. H.

2008-06-01

6

Cold atmospheric pressure plasma jet interactions with plasmid DNA  

NASA Astrophysics Data System (ADS)

The effect of a cold (<40 °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.

2011-01-01

7

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

8

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

Microsoft Academic Search

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

Q. Xiong; X. Lu; J. Liu; Y. Xian; Z. Xiong; F. Zou; C. Zou; W. Gong; J. Hu; K. Chen; X. Pei; Z. Jiang; Y. Pan

2009-01-01

9

The Interaction of a Direct-Current Cold Atmospheric-Pressure Air Plasma With Bacteria  

Microsoft Academic Search

A direct-current cold atmospheric-pressure air plasma microjet (PMJ) based on the microhollow cathode discharge design is used to inactivate six types of bacteria within a small well-defined area on a large Petri dish. We show that the PMJ is very effective in inactivating bacteria in their vegetative state as well as in the spore state within the area of plasma

Hongqing Feng; Peng Sun; Yufeng Chai; Guohua Tong; Jue Zhang; Weidong Zhu; Jing Fang

2009-01-01

10

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

2012-12-13

11

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

12

Development of a new atmospheric pressure cold plasma jet generator and application in sterilization  

NASA Astrophysics Data System (ADS)

This paper reports that a new plasma generator at atmospheric pressure, which is composed of two homocentric cylindrical all-metal tubes, successfully generates a cold plasma jet. The inside tube electrode is connected to ground, the outside tube electrode is connected to a high-voltage power supply, and a dielectric layer is covered on the outside tube electrode. When the reactor is operated by low-frequency (6 kHz-20 kHz) AC supply in atmospheric pressure and argon is steadily fed as a discharge gas through inside tube electrode, a cold plasma jet is blown out into air and the plasma gas temperature is only 25-30°C. The electric character of the discharge is studied by using digital real-time oscilloscope (TDS 200-Series), and the discharge is capacitive. Preliminary results are presented on the decontamination of E.colis bacteria and Bacillus subtilis bacteria by this plasma jet, and an optical emission analysis of the plasma jet is presented in this paper. The ozone concentration generated by the plasma jet is 1.0×1016cm-3 which is acquired by using the ultraviolet absorption spectroscopy.

Cheng, Cheng; Liu, Peng; Xu, Lei; Zhang, Li-Ye; Zhan, Ru-Juan; Zhang, Wen-Rui

2006-07-01

13

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

14

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

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

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

17

Inactivation of Escherichia coli ATCC 11775 in fresh produce using atmospheric pressure cold plasma  

NASA Astrophysics Data System (ADS)

Food-borne outbreaks are associated with the presence of pathogenic bacteria in food products such as fresh produce. One of the target microorganisms is Escherichia coli which exhibits resistance to being inactivated with conventional disinfection methods for vegetables. Atmospheric pressure cold plasma (APCP) was tested to disinfect three vegetables with challenge surfaces, lettuce, carrots and tomatoes. The produce was inoculated with the bacteria to reach an initial microbial concentration of 10^7 cfu/g. Vegetables were initially exposed to the APCP discharges from a needle array at 5.7 kV RMS in argon, processing times of 0.5, 3 and 5 min. Initial results indicate that microbial decontamination is effective on the lettuce (1.2 log reduction) when compared with other vegetables. To claim disinfection, a 3 log reduction or more is needed, which makes APCP treatment very promising technology for decontamination of produce. We propose that with method refinements full disinfection can be achieved using APCP.

Bermudez-Aguirre, Daniela; Wemlinger, Erik; Barbosa-Canovas, Gustavo; Pedrow, Patrick; Garcia-Perez, Manuel

2011-11-01

18

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

19

Antimicrobial impact of cold atmospheric pressure plasma on medical critical yeasts and bacteria cultures.  

PubMed

Objectives: Plasma medicine focuses on the application of cold atmospheric pressure plasmas (CAPs) in or on the human body. So far, plasmas have been used to sterilize implant materials or other thermally unstable medical products and have been applied for chemical surface modifications. This study investigates the antimicrobial effect of physical plasmas on microorganisms which cause skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans, depending on the plasma source and the kind of plasma excitation used. Materials: Microorganisms were plated onto MH2 agar plates. Plasma treatment was performed using the plasma sources BLASTER MEF and kinpen 09. To investigate the antimicrobial effects, the following plasma parameters have been varied: working gas, distance from nozzle to surface, electrical power, grid spacing of treatment lines, number of treatments and work piece velocity. Results: The generated plasmas had an antimicrobial effect that depended on the chosen plasma parameters, in particular on the process gas used, the plasma power and the number of treatments performed. Thus, different reactive species were observed by optical emission spectroscopy measurement in the generated plasmas. Conclusions: The study showed that CAPs exhibit profound bactericidal and fungicidal properties in vitro. However, an important factor for the antimicrobial efficacy is the composition of the 'chemical soup' supplied by the CAP system which can be regulated by the process gases used. © 2013 S. Karger AG, Basel. PMID:23921169

Wiegand, C; Beier, O; Horn, K; Pfuch, A; Tölke, T; Hipler, U-C; Schimanski, A

2013-08-01

20

FAST TRACK COMMUNICATION: A cold atmospheric pressure plasma jet controlled with spatially separated dual-frequency excitations  

Microsoft Academic Search

A dual-frequency cold atmospheric pressure plasma (CAP) jet is studied as a possible route to separate control of basic plasma parameters particularly plasma density, plasma plume length and gas temperature. With spatially separate application of two excitation frequencies, one at 5.5 MHz and the other at 30 kHz, plasma dynamics exhibit interaction between influences by the two individual excitation frequencies.

Z. Cao; Q. Y. Nie; M. G. Kong

2009-01-01

21

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

22

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

23

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

SciTech Connect

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{center_dot}) and superoxide anion radical (O{sub 2}{sup -}{center_dot}) adducts were observed when neutral oxygen gas was additionally supplied to the plasma. In particular, O{sub 2}{sup -}{center_dot} 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 O{sub 2}{sup -}{center_dot} is crucial for sterilization of liquids via atmospheric-pressure plasma.

Tani, Atsushi; Fukui, Satoshi [Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Ono, Yusuke; Kitano, Katsuhisa [Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Ikawa, Satoshi [Technology Research Institute of Osaka Prefecture, Izumi, Osaka 594-1157 (Japan)

2012-06-18

24

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

Microsoft Academic Search

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

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

2011-01-01

25

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

26

Development of a cold atmospheric pressure microplasma jet for freeform cell printing  

NASA Astrophysics Data System (ADS)

An atmospheric pressure non-thermal microplasma jet (Ø 50 ?m) was developed for localized functionalization of various substrates, including polymers, to allow maskless freeform cell printing. The applied microplasma jet power ranged from 0.1 to 0.2 W without causing any damage to the polyethylene substrate. The surface characterization results demonstrate that the microplasma treatment locally changes the surface roughness and the concentration of oxygen-containing functional groups on the polyethylene surface. The biological characterization confirms that the osteoblast cells attach and survive on the plasma activated line while untreated surfaces show almost no attachment and viability.

Ayan, Halim; Yildirim, Eda D.; Pappas, Daphne D.; Sun, Wei

2011-09-01

27

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

2013-09-25

28

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

29

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

NASA Astrophysics Data System (ADS)

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.

2012-05-01

30

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

31

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

32

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

33

Correlation of streamer current pulses associated with adjacent high voltage needles in atmospheric pressure cold plasma reactors  

NASA Astrophysics Data System (ADS)

We hypothesize that for a 12 needle array in an atmospheric pressure cold plasma reactor there will be correlation between needle corona current pulses. Guaitella et al. have shown in their surface dielectric barrier discharge that synchronous surface streamers are likely triggered by photodesorbed negative charges with binding energy (at the surface of the dielectric) less than 3.5 eV.ootnotetextO. Guaitella, I. Marinov, A. Rousseau, Applied Physics Letters, 98, 2011. The reactor used in our work has two rings of axially aligned needles. The current in each needle is measured with broad band current sensors that respond primarily to free electron drift. Digital signal processing will be used to analyze correlation between streamer current pulses. A 60 Hz 10 kVRMS voltage source produces the streamers and concomitantly the cold plasma. The current pulse correlation will be studied between 1 needle and each of the other 11 needles with the expectation that nearest neighbor needles will have the highest correlation. Understanding correlated streamer current pulses will inform reactor modeling and reactor optimization.

Wemlinger, Erik; Pedrow, Patrick

2011-11-01

34

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

35

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

36

Cold Atmospheric-Pressure Plasmas Applied to Active Packaging of Fruits and Vegetables  

NASA Astrophysics Data System (ADS)

Active packaging of fruits and vegetables uses films that absorb molecules from or contribute molecules to the produce. Applying uniform film to specific parts of a plant will enhance safe and economic adoption of expensive biofilms and biochemicals which would damage the plant or surrounding environment if misapplied. The pilot application will be to apply wax film to apples, replacing hot wax which is expensive and lowers the textural quality of the apple. The plasma zone will be obtained by increasing the voltage on an electrode structure until the electric field in the feed material (Argon + monomer) is sufficiently high to yield electron avalanches. The ``corona onset criterion'' is used to design the cold plasma reactor. The apple will be placed in a treatment chamber downstream from the activation zone. Key physical properties of the film will be measured. The deposition rate will be optimized in terms of economics and fruit surface quality for the purpose of determining if the technique is competitive in food processing plants.

Pedrow, Patrick; Fernandez, Sulmer; Pitts, Marvin

2008-10-01

37

Interactions between atmospheric pressure plasma jets  

Microsoft Academic Search

Cold atmospheric pressure plasmas offer a unique environment for treatments of soft materials. Here we investigate the possibility of exploiting the interaction of two or more atmospheric pressure plasma jets for increased control and manipulation. The interaction zone itself offers the possibility of a more controllable gentle environment for delicate treatments. The interaction between two counter-streaming atmospheric pressure plasma jets

Qais Th. Algwari; Colm O'Neill; Deborah O'Connell

2009-01-01

38

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

PubMed

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. PMID:23967387

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

2013-04-29

39

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

40

Surface Treatment of Flat Panel Display Substrates by a Uniform Large Area Glow Cold Plasma Tunnel at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

A novel, uniform, continuous, atmospheric pressure plasma tunnel (APPT), which was 400 × 175 × 2 mm3, had been developed for surface treatment of flat panel display (FPD) glass substrates in-line at atmospheric pressure with gas mixtures containing argon and oxygen. The electrical properties of the glow plasma tunnel were presented by simultaneous measurement of current and voltage and the results showed that there were a big phase shift and big different amplitudes of current waveforms, which were due to the variation of the capacitance between the discharge electrodes, when the FPD glass substrate passed through the tunnel. The effects of the plasma treatment on the surface of the FPD glass substrate had also been studied by using contact angle measurement and scanning probe microscopy (SPM). The results showed that the wettability of the surface had an obvious improvement after the plasma treatment with the time of 10 second.

Wang, Shouguo; Wan, Jun; Jia, Xianghong; Zhao, Lingli

2009-09-01

41

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

Microsoft Academic Search

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,

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

2008-01-01

42

Development of an atmospheric-pressure homogeneous and cold Ar/O{sub 2} plasma source operating in glow discharge  

SciTech Connect

An atmospheric-pressure Ar/O{sub 2} 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/O{sub 2} 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 Shouzhe; Wu Qi; Zhang Jialiang; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 137-701 (Korea, Republic of)

2010-06-15

43

Effect of cathode microstructure on arc velocity and erosion rate of cold cathodes in magnetically rotated atmospheric pressure arcs  

NASA Astrophysics Data System (ADS)

Atmospheric pressure arc velocity and arc erosion measurements were performed on thermal sprayed copper cathodes having grain size distributions from submicrometre to a few micrometres in a continuous running arc system. Ultrahigh purity (UHP), 99.99% pure, argon and a mixture of UHP argon with 10% (volumetric) extra dry air were used as plasma forming gases. An external magnetic field of 0.10 T was used to rotate the arc which was operated at a constant power setting of 6 kW (150 A and 40 V). Cathodes having different microstructures were formed using high velocity oxygen fuel (HVOF) spraying and vacuum plasma spraying (VPS) methods with different annealing times. HVOF sprayed cathodes were tested for arc erosion and arc velocity in their as-sprayed state and also after annealing them at 300 and 600 °C for 1 and 8 h durations in an inert argon atmosphere. VPS sprayed coatings were tested as-sprayed. The effect of the initial coating thickness on erosion rates was investigated. Annealing HVOF coatings at 600 °C for 8 h produced near equi-axed grains with a 2-3 µm average size. These coatings showed 60% higher steady state arc velocities and up to 68% lower erosion rates compared with massive copper cathodes having a 20-23 µm average grain size. VPS coatings having a 0.9-1.5 µm average grain size gave up to 70% lower erosion rates when compared with massive copper cathodes. The results show a clear effect of the cathode microstructure on the arc velocity and the erosion rate.

Rao, Lakshminarayana; Munz, Richard J.

2008-08-01

44

Mechanisms of bacterial inactivation in the liquid phase induced by a remote RF cold atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

A radio-frequency atmospheric pressure argon plasma jet is used for the inactivation of bacteria (Pseudomonas aeruginosa) in solutions. The source is characterized by measurements of power dissipation, gas temperature, absolute UV irradiance as well as mass spectrometry measurements of emitted ions. The plasma-induced liquid chemistry is studied by performing liquid ion chromatography and hydrogen peroxide concentration measurements on treated distilled water samples. Additionally, a quantitative estimation of an extensive liquid chemistry induced by the plasma is made by solution kinetics calculations. The role of the different active components of the plasma is evaluated based on either measurements, as mentioned above, or estimations based on published data of measurements of those components. For the experimental conditions being considered in this work, it is shown that the bactericidal effect can be solely ascribed to plasma-induced liquid chemistry, leading to the production of stable and transient chemical species. It is shown that HNO2, ONOO- and H2O2 are present in the liquid phase in similar quantities to concentrations which are reported in the literature to cause bacterial inactivation. The importance of plasma-induced chemistry at the gas-liquid interface is illustrated and discussed in detail.

van Gils, C. A. J.; Hofmann, S.; Boekema, B. K. H. L.; Brandenburg, R.; Bruggeman, P. J.

2013-05-01

45

A study of eukaryotic response mechanisms to atmospheric pressure cold plasma by using Saccharomyces cerevisiae single gene mutants  

NASA Astrophysics Data System (ADS)

The mechanisms of eukaryotic cell response to cold plasma are studied. A series of single gene mutants of eukaryotic model organism Saccharomyces cerevisiae are used to compare their sensitivity to plasma treatment with the wild type. We examined 12 mutants in the oxidative stress pathway and the cell cycle pathway, in which 8 are found to be hypersensitive to plasma processing. The mutated genes' roles in the two pathways are analyzed to understand the biological response mechanisms of plasma treatment. The results demonstrate that genes from both pathways are needed for the eukaryotic cells to survive the complex plasma treatment.

Feng, Hongqing; Wang, Ruixue; Sun, Peng; Wu, Haiyan; Liu, Qi; Fang, Jing; Zhu, Weidong; Li, Fangting; Zhang, Jue

2010-09-01

46

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

47

Treating lamb’s lettuce with a cold plasma – Influence of atmospheric pressure Ar plasma immanent species on the phenolic profile of Valerianella locusta  

Microsoft Academic Search

The antimicrobial effectiveness of non-thermal plasma is scientifically accepted. Applications can be found in medicinal sterilisation processes. However, the effects of plasma treatments on plant food with regard to nutritional value are not yet sufficiently investigated. To study the interactions of plasma immanent reactive species with secondary plant metabolites, lamb’s lettuce (Valerianella locusta) was exposed to an atmospheric pressure plasma

Franziska Grzegorzewski; Jörg Ehlbeck; Oliver Schlüter; Lothar W. Kroh; Sascha Rohn

2011-01-01

48

Cold denaturation of proteins under high pressure  

Microsoft Academic Search

The advantageous usage of the high pressure technique in studies of cold denaturation of proteins is reviewed, with a brief explanation of the theoretical background of this universal phenomenon. Various experimental results are presented and discussed, explaining the plausible image of the cold denatured state of proteins. In order to understand more clearly this phenomenon and protein structure transition in

Shigeru Kunugi; Naoki Tanaka

2002-01-01

49

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

50

Atmospheric-Pressure Plasma Process and Applications.  

National Technical Information Service (NTIS)

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 ...

P. Kong

2006-01-01

51

Blood Pressure: Is It Affected by Cold Weather?  

MedlinePLUS

... only. Blood pressure: Is it affected by cold weather? By Mayo Clinic staff Original Article: http://www. ... Question Blood pressure: Is it affected by cold weather? Can cold weather or seasonal changes in weather ...

52

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

53

Atmospheric-pressure plasma jet  

Microsoft Academic Search

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

Selwyn; Gary S

1999-01-01

54

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

55

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

56

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

57

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

58

Extratropical Atmospheric Response to Equatorial Atlantic Cold Tongue Anomalies  

Microsoft Academic Search

Abstract The extra-tropical atmospheric response to the equatorial cold tongue mode,in the Atlantic Ocean has been investigated with the coupled ocean-atmosphere model SPEEDO. Similar as in the observations the model simulates a lagged co-variability between the equatorial cold tongue mode,during late boreal summer,and the east Atlantic pattern a few months later in early winter. The equatorial cold tongue mode,attains its

Reindert J. Haarsma; Wilco Hazeleger

2007-01-01

59

Absolute OH density measurements in the effluent of a cold atmospheric-pressure Ar-H2O RF plasma jet in air  

NASA Astrophysics Data System (ADS)

Absolute OH densities are obtained in a radio-frequency-driven Ar-H2O atmospheric-pressure plasma jet by laser-induced fluorescence (LIF), calibrated by Rayleigh scattering and by UV broadband absorption. The measurements are carried out in ambient air and the effect of air entrainment into the Ar jet is measured by analyzing the time-resolved fluorescence signals. The OH densities are obtained for different water vapor concentrations admixed to the Ar and as a function of the axial distance from the nozzle. A sensitivity analysis to deduce the accuracy of the model-calculated OH density from the LIF measurement is reported. It is found that the UV absorption and the LIF results correspond within experimental accuracy close to the nozzle and deviate in the far effluent. The possible reasons are discussed. The OH densities found in the plasma jet are in the range (0.1-2.5) × 1021 m-3 depending on the water concentration and plasma conditions.

Verreycken, Tiny; Mensink, Rob; van der Horst, Ruud; Sadeghi, Nader; Bruggeman, Peter J.

2013-10-01

60

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

61

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

62

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

63

Sterilization effects of atmospheric cold plasma brush  

SciTech Connect

This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0x10{sup 4}-1.0x10{sup 5} Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar+O{sub 2} 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 [Center for Surface Science and Plasma Technology, and Department of Chemical Engineering, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Department of Biological Engineering, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2006-01-02

64

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

65

Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean during the North Atlantic cold events of the past 50 k.y  

Microsoft Academic Search

Multiproxy paleoenvironmental records (pollen and planktonic isotope) from Ocean Drilling Program Site 976 (Alboran Sea) document rapid ocean and climate variations during the last glacial that follow the Dansgaard-Oeschger climate oscillations seen in the Greenland ice core records, thus suggesting a close link of the Mediterranean climate swings with North Atlantic climates. Continental conditions rapidly oscillated through cold-arid and warm-wet

N. Combourieu Nebout; J. L. Turon; R. Zahn; L. Capotondi; L. Londeix; K. Pahnke

2002-01-01

66

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

67

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

68

Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets  

SciTech Connect

Pulsed excitation of cold atmospheric plasmas is commonly believed to offer valuable benefits compared to the mainstream sinusoidal excitation. However, direct comparison of pulsed and sinusoidal atmospheric plasmas remains few, if any, thus casting an uncertainty of whether pulsed excitation facilitates any significant advantage. In this letter, we report a comparison study of pulsed and sinusoidal cold atmospheric plasma jets through electrical characterization, gas temperature measurement, and optical detection of reactive plasma species. An example of pulsed excitation is shown to reduce the electrical energy consumption by a factor of 12 for producing the same amount of oxygen atoms.

Walsh, J.L.; Shi, J.J.; Kong, M.G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

2006-04-24

69

Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets  

NASA Astrophysics Data System (ADS)

Pulsed excitation of cold atmospheric plasmas is commonly believed to offer valuable benefits compared to the mainstream sinusoidal excitation. However, direct comparison of pulsed and sinusoidal atmospheric plasmas remains few, if any, thus casting an uncertainty of whether pulsed excitation facilitates any significant advantage. In this letter, we report a comparison study of pulsed and sinusoidal cold atmospheric plasma jets through electrical characterization, gas temperature measurement, and optical detection of reactive plasma species. An example of pulsed excitation is shown to reduce the electrical energy consumption by a factor of 12 for producing the same amount of oxygen atoms.

Walsh, J. L.; Shi, J. J.; Kong, M. G.

2006-04-01

70

GCM simulations of cold dry Snowball Earth atmospheres  

Microsoft Academic Search

We use the full-physics atmospheric general circulation model ECHAM5 to investigate cold and virtually dry Snowball Earth atmospheres. These result from specifying sea ice as the surface boundary condition everywhere, corresponding to a frozen aquaplanet, while keeping total solar irradiance at its present-day value of 1365 Wm-2 and setting atmospheric carbon dioxide to 300 ppmv. Here, we present four simulations

A. Voigt; I. Held; J. Marotzke

2009-01-01

71

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

2012-05-15

72

Atmospheric science: Coming in from the cold  

NASA Astrophysics Data System (ADS)

The abundance of some persistent organic pollutants has decreased in the Arctic atmosphere over recent years. But observations and model simulations confirm that warming is now remobilizing these toxic chemicals from sinks such as ice and sea water.

Dachs, Jordi

2011-08-01

73

Atmospheric science: Coming in from the cold  

Microsoft Academic Search

The abundance of some persistent organic pollutants has decreased in the Arctic atmosphere over recent years. But observations and model simulations confirm that warming is now remobilizing these toxic chemicals from sinks such as ice and sea water.

Jordi Dachs

2011-01-01

74

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

75

A streamer-like atmospheric pressure plasma jet  

Microsoft Academic Search

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 107 cm?s. Using spatially and temporally resolved optical diagnostics, it is demonstrated that the plasma jet

Brian L. Sands; Biswa N. Ganguly; Kunihide Tachibana

2008-01-01

76

A streamer-like atmospheric pressure plasma jet  

Microsoft Academic Search

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 107 cm\\/s. Using spatially and temporally resolved optical diagnostics, it is demonstrated that the plasma jet

Brian L. Sands; Biswa N. Ganguly; Kunihide Tachibana

2008-01-01

77

Double-Layered Atmospheric Pressure Plasma Jet  

Microsoft Academic Search

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

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

2009-01-01

78

Determining Atmospheric Pressure Using a Water Barometer  

NASA Astrophysics Data System (ADS)

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 mass of the water that is used as the fluid medium in the barometer. Simple calculations based upon the mass of water collected from the barometer yield the mass of the atmosphere per square unit of area at the site where the experiment is conducted.

Lohrengel, C. Frederick; Larson, Paul R.

2012-12-01

79

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

80

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

81

Topographic and Atmospheric Pressure Mapping of Mars  

NASA Astrophysics Data System (ADS)

Ground-based near-infrared images and spectral observations of Mars are shown to provide relatively detailed topographic images of the martian surface and may be used to obtain martian atmospheric pressure system information.

Chamberlain, S.; Bailey, J.; Crisp, D.; Walter, M.

2006-03-01

82

Large area atmospheric-pressure plasma jet  

Microsoft Academic Search

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

Gary S. Selwyn; Ivars Henins; Steve E. Babayan; Robert F. Hicks

2001-01-01

83

Direct characterization of hydrophobic hydration during cold and pressure denaturation.  

PubMed

Cold and pressure denaturation are believed to have their molecular origin in hydrophobic interactions between nonpolar groups and water. However, the direct characterization of the temperature- and pressure-dependent variations of those interactions with atomistic simulations remains challenging. We investigated the role of solvent in the cold and pressure denaturation of a model hydrophobic 32-mer polymer by performing extensive coarse-grained molecular dynamics simulations including explicit solvation. Our simulations showed that the water-excluded folded state of this polymer is marginally stable and can be unfolded by heating or cooling, as well as by applying pressure, similar to globular proteins. We further detected essential population of a hairpin-like configuration prior to the collapse, which is consistently accompanied by a vapor bubble at the elbow of the kink. Increasing pressure suppresses formation of this vapor bubble by reducing water fluctuations in the hydration shell of the polymer, thus promoting unfolding. Further analysis revealed a slight reduction of water tetrahedrality in the polymer hydration shell compared to the bulk. Cold denaturation is driven by an enhanced tetrahedral ordering of hydration shell water than bulk water. At elevated pressures, the strikingly reduced fluctuations combined with the increase in interstitial water molecules in the polymer hydration shell contribute to weakening of hydrophobic interactions, thereby promoting pressure unfolding. These findings provide critical molecular insights into the changes in hydrophobic hydration during cold and pressure unfolding of a hydrophobic polymer, which is strongly related to the cold and pressure denaturation of globular proteins. PMID:22512347

Das, Payel; Matysiak, Silvina

2012-05-02

84

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.

85

Possible mechanism for cold denaturation of proteins at high pressure.  

PubMed

We study cold denaturation of proteins at high pressures. Using multicanonical Monte Carlo simulations of a model protein in a water bath, we investigate the effect of water density fluctuations on protein stability. We find that above the pressure where water freezes to the dense ice phase (approximately 2 kbars) the mechanism for cold denaturation with decreasing temperature is the loss of local low-density water structure. We find our results in agreement with data of bovine pancreatic ribonuclease A. PMID:14525339

Marqués, Manuel I; Borreguero, Jose M; Stanley, H Eugene; Dokholyan, Nikolay V

2003-09-26

86

Possible Mechanism for Cold Denaturation of Proteins at High Pressure  

NASA Astrophysics Data System (ADS)

We study cold denaturation of proteins at high pressures. Using multicanonical Monte Carlo simulations of a model protein in a water bath, we investigate the effect of water density fluctuations on protein stability. We find that above the pressure where water freezes to the dense ice phase (?2 kbars) the mechanism for cold denaturation with decreasing temperature is the loss of local low-density water structure. We find our results in agreement with data of bovine pancreatic ribonuclease A.

Marqués, Manuel I.; Borreguero, Jose M.; Stanley, H. Eugene; Dokholyan, Nikolay V.

2003-09-01

87

Possible Mechanism for Cold Denaturation of Proteins at High Pressure  

Microsoft Academic Search

We study cold denaturation of proteins at high pressures. Using\\u000amulticanonical Monte Carlo simulations of a model protein in a water bath, we\\u000ainvestigate the effect of water density fluctuations on protein stability. We\\u000afind that above the pressure where water freezes to the dense ice phase\\u000a($\\\\approx2$ kbar), the mechanism for cold denaturation with decreasing\\u000atemperature is the loss

Manuel I. Marques; Jose M. Borreguero; H. Eugene Stanley; Nikolay V. Dokholyan

2003-01-01

88

[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

89

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

90

Optical diagnostics of atmospheric pressure air plasmas  

Microsoft Academic Search

Atmospheric pressure air plasmas are often thought to be in local thermodynamic equilibrium owing to fast interspecies collisional exchange at high pressure. This assumption cannot be relied upon, particularly with respect to optical diagnostics. Velocity gradients in flowing plasmas and\\/or elevated electron temperatures created by electrical discharges can result in large departures from chemical and thermal equilibrium. This paper reviews

C O Laux; T G Spence; C H Kruger; R N Zare

2003-01-01

91

Seasonal Behaviour of Atmospheric Pressure Oscillations  

Microsoft Academic Search

IT is well known that the atmospheric pressure at any given point does not remain constant in time and is subject to periodic and non-periodic fluctuations. Statistical analyses have been used to establish them and many investigations have been published. This communication reports the results of a spectral density analysis performed for the barometric pressure data at the Langmuir Laboratory

Bhartendu; J. A. Allen; G. W. Paltridge; M. H. Wilkening

1967-01-01

92

DIAGNOSTICS OF ATMOSPHERIC PRESSURE AIR PLASMAS  

Microsoft Academic Search

Atmospheric pressure air plasmas are often thought to be in Local Thermodynamics Equilibrium (LTE) owing to fast interspecies collisional exchanges at high pressure. As will be seen here, this assumption cannot be relied upon, particularly with respect to optical diagnostics. Large velocity gradients in flowing plasmas and\\/or elevated electron temperatures created by electrical discharges can result in large departures from

C. O. Laux; C. H. Kruger; R. N. Zare

93

Diagnostics on an atmospheric pressure plasma jet  

Microsoft Academic Search

The atmospheric pressure plasma jet (APPJ) is a homogeneous non-equilibrium discharge at ambient pressure. It operates with a noble base gas and a percentage-volume admixture of a molecular gas. Applications of the discharge are mainly based on reactive species in the effluent. The effluent region of a discharge operated in helium with an oxygen admixture has been investigated. The optical

K. Niemi; St. Reuter; L. Schaper; N. Knake; V. Schulz-von der Gathen; T. Gans

2007-01-01

94

Measuring the atmosphere : temperature, pressure and ozone  

NSDL National Science Digital Library

How does altitude affect temperature and pressure? This page, part of an interactive laboratory series for grades 8-12, provides students with information for an interactive laboratory activity on the effects of altitude on temperature and pressure and the location of ozone in the atmosphere. The activity enables students to collect three sets of data on temperature, pressure, and ozone concentration as a gas-filled balloon equipped with data collection equipment rises through the atmosphere. Students determine how often and at what altitude to collect data. Questions about each graphed data set are provided. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

95

Evaporation of urea at atmospheric pressure.  

PubMed

Aqueous urea solution is widely used as reducing agent in the selective catalytic reduction of NO(x) (SCR). Because reports of urea vapor at atmospheric pressure are rare, gaseous urea is usually neglected in computational models used for designing SCR systems. In this study, urea evaporation was investigated under flow reactor conditions, and a Fourier transform infrared (FTIR) spectrum of gaseous urea was recorded at atmospheric pressure for the first time. The spectrum was compared to literature data under vacuum conditions and with theoretical spectra of monomolecular and dimeric urea in the gas phase calculated with the density functional theory (DFT) method. Comparison of the spectra indicates that urea vapor is in the monomolecular form at atmospheric pressure. The measured vapor pressure of urea agrees with the thermodynamic data obtained under vacuum reported in the literature. Our results indicate that considering gaseous urea will improve the computational modeling of urea SCR systems. PMID:21381736

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

2011-03-07

96

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 [1]. 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 and 95 krpm, with a speed of 80 krpm 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.; /Fermilab

2003-01-01

97

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

98

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

99

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

100

Electron density and temperature measurements in the cold plasma environment of Titan: Implications for atmospheric escape  

NASA Astrophysics Data System (ADS)

We present electron temperature and density measurements of Titan's cold ionospheric plasma from the Langmuir probe instrument on Cassini from 52 flybys. An expression of the density as a function of temperature is presented for altitudes below two Titan radii. The density falls off exponentially with increased temperature as log(ne) = -2.0log(Te) + 0.6 on average around Titan. We show that this relation varies with location around Titan as well as with the solar illumination direction. Significant heating of the electrons appears to take place on the night/wake side of Titan as the density-temperature relation is less steep there. Furthermore, we show that the magnetospheric ram pressure is not balanced by the thermal and magnetic pressure in the topside ionosphere and discuss its implications for plasma escape. The cold ionospheric plasma of Titan extends to higher altitudes in the wake region, indicating the loss of atmosphere down the induced magnetospheric tail.

Edberg, N. J. T.; Wahlund, J.-E.; Ågren, K.; Morooka, M. W.; Modolo, R.; Bertucci, C.; Dougherty, M. K.

2010-10-01

101

An Atmospheric-Pressure Helium Plasma Jet Induced by an Atmospheric-Pressure Argon Plasma Discharge in a Single-Electrode Configuration  

Microsoft Academic Search

An atmospheric-pressure (AP) cold helium plasma jet is induced by an argon plasma discharge generated in a single-electrode configuration at AP. The dependences of the length of the downstream and upstream helium plasma jets on the angle between gas flow directions of helium and argon, the applied voltage on the single electrode, and the gas flow rate of helium are

Shou-Zhe Li; Wen-Tong Huang; Dezhen Wang

2009-01-01

102

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

103

Electron heating in atmospheric pressure glow discharges  

Microsoft Academic Search

The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and

Robert H. Stark; Karl H. Schoenbach

2001-01-01

104

Formation Mechanism of Atmospheric Pressure Plasma Jet  

Microsoft Academic Search

Atmospheric pressure plasma jet can protrude some 5.0 cm into air. It holds promise for multivarious innovative applications, but its formation mechanism remains unsettled. We show that the plasma jet is essentially a streamer corona totally independent of, but obscured by, dielectric barrier discharge. Consequently, the jets can be equally successfully generated even with one single bare metal electrode attached

Nan Jiang; Ailing Ji; Zexian Cao

2008-01-01

105

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

106

Atmospheric Pressure Fluidized Bed Coal Combustion Test.  

National Technical Information Service (NTIS)

A pilot plant is realized for the combustion of coal in a fluidized bed at atmospheric pressure, with a bed cooled by immersed exchangers. Technological devices and the associated operating conditions are developed. In particular, pre-heating of the bed, ...

N. Meysson B. Grue

1982-01-01

107

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

108

Magnetized Neutron Star Atmospheres: Beyond the Cold Plasma Approximation  

NASA Astrophysics Data System (ADS)

All the neutron star (NS) atmosphere models published so far have been calculated in the "cold plasma approximation," which neglects the relativistic effects in the radiative processes, such as cyclotron emission/absorption at harmonics of cyclotron frequency. Here, we present new NS atmosphere models which include such effects. We calculate a set of models for effective temperatures T eff = 1-3 MK and magnetic fields B ~ 1010-1011 G, typical for the so-called central compact objects (CCOs) in supernova remnants, for which the electron cyclotron energy E c, e and its first harmonics are in the observable soft X-ray range. Although the relativistic parameters, such as kT eff/mec 2 and E c, e /mec 2, are very small for CCOs, the relativistic effects substantially change the emergent spectra at the cyclotron resonances, E ? sE c, e (s = 1, 2, ...). Although the cyclotron absorption features can form in a cold plasma due to the quantum oscillations of the free-free opacity, the shape and depth of these features change substantially if the relativistic effects are included. In particular, the features acquire deep Doppler cores, in which the angular distribution of the emergent intensity is quite different from that in the cold plasma approximation. The relative contributions of the Doppler cores to the equivalent widths of the features grow with increasing quantization parameter b eff ? E c, e /kT eff and harmonic number s. The total equivalent widths of the features can reach ~150-250 eV; they increase with growing b eff and are smaller for higher harmonics.

Suleimanov, V. F.; Pavlov, G. G.; Werner, K.

2012-05-01

109

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

110

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

111

Research on atmospheric pressure plasma processing sewage  

NASA Astrophysics Data System (ADS)

The water pollution has become more and more serious with the industrial progress and social development, so it become a worldwide leading environmental management problem to human survival and personal health, therefore, countries are looking for the best solution. Generally speaking, in this paper the work has the following main achievements and innovation: (1) Developed a new plasma device--Plasma Water Bed. (2) At atmospheric pressure condition, use oxygen, nitrogen, argon and helium as work gas respectively, use fiber spectrometer to atmospheric pressure plasma discharge the emission spectrum of measurement, due to the different work gas producing active particle is different, so can understand discharge, different particle activity, in the treatment of wastewater, has the different degradation effects. (3) Methyl violet solution treatment by plasma water bed. Using plasma drafting make active particles and waste leachate role, observe the decolorization, measurement of ammonia nitrogen removal.

Song, Gui-cai; Na, Yan-xiang; Dong, Xiao-long; Sun, Xiao-liang

2013-08-01

112

Atmospheric pressure plasma jet for decontamination purposes  

NASA Astrophysics Data System (ADS)

Advanced oxidation processes, especially induced by non-thermal plasmas, are widely known for their high sanitation efficiency. The paper presents general overview of atmospheric pressure plasma jet (APPJ) reactors for bactericidal decontamination purposes. In the conclusion part, the basic requirements for APPJ as a tool for biomedical applications including the treatment of living tissues are highlighted. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

Paw?at, Joanna

2013-02-01

113

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

114

Physiological Action of Diminished Atmospheric Pressure  

Microsoft Academic Search

WITH reference to the effect of diminished atmospheric pressure on the vital powers, alluded to in Prof. Bonney's review of Mr. Whymper's ``Travels among the Great Andes of the Equator'' (NATURE, April 14, p. 561), I do not know whether it is worth while recalling the well-known fact that numerous passes in the Himalayas, ranging from 17,000 to 19,000 feet,

F. R. Mallet

1892-01-01

115

Reverse Propagation of Atmospheric Pressure Plasma Jets  

Microsoft Academic Search

Bullet-like propagation of individual bright spots has been observed using photomultiplier tubes in helium atmospheric pressure plasma jets with dielectric barrier discharges. Under typical discharge conditions, such optical-emission spots in plasma jets (also known as ``plasma bullets'') are known to propagate in the direction of the applied electric field. Results of this study show that similar optical-emission spots can also

Tsuyohito Ito; Aurélien Raddenzati; Artabaze Shams; Satoshi Hamaguchi

2010-01-01

116

Apoptosis in vascular cells induced by cold atmospheric plasma treatment  

NASA Astrophysics Data System (ADS)

Apoptosis is a natural mechanism of cellular self-destruction. It can be triggered by moderate, yet irreversible damage. Apoptosis plays a major role in tissue renewal. Artificial apoptosis induction will become a novel therapy that meets all requirements for tissue-saving surgery. Diseased tissues can disappear without inflammation and scarring. This is particularly important in treatment of blockages in body tracts (e.g. cardiovascular diseases). Artificial induction of apoptosis can be achieved by means of cold plasma treatment. In this work an atmospheric micro-plasma operated in helium/air has been used to induce apoptosis in vascular cells. Parametric studies of apoptosis induction have been conducted; the efficiency is almost 100%. The apoptotic factors are ROS/RNS (reactive oxygen and nitrogen species). Their densities in the plasma have been measured by mass spectrometry. For apoptosis induction, RNS seem to be more important than ROS, because of their relative abundance. Moreover, addition of a ROS scavenger (ascorbic acid) to the cell culture medium does not reduce the occurrence of apoptosis. Cold plasma is a very efficient tool for fundamental studies of apoptosis, and later, for controlled tissue removal in vivo.

Sladek, Raymond; Stoffels, Eva

2006-10-01

117

Unifying microscopic mechanism for pressure and cold denaturations of proteins.  

PubMed

We study the stability of globular proteins as a function of temperature and pressure through NPT simulations of a coarse-grained model. We reproduce the elliptical stability of proteins and highlight a unifying microscopic mechanism for pressure and cold denaturations. The mechanism involves the solvation of nonpolar residues with a thin layer of water. These solvated states have lower volume and lower hydrogen-bond energy compared to other conformations of nonpolar solutes. Hence, these solvated states are favorable at high pressure and low temperature, and they facilitate protein unfolding under these thermodynamical conditions. PMID:23006112

Dias, Cristiano L

2012-07-27

118

Investigations on the generation of atomic oxygen inside a capacitively coupled atmospheric pressure plasma jet  

Microsoft Academic Search

Inside a miniaturized capacitively coupled cold atmospheric pressure plasma jet operated at a helium base gas flow with a minor molecular oxygen admixture atomic oxygen is created. The build up of atomic oxygen along the discharge channel and its further decay in the effluent is investigated by means of xenon calibrated two photon laser induced fluorescence spectroscopy (TALIF). The longitudinal

N. Knake; D. Schröder; J. Winter; V. Schulz-von der Gathen

2010-01-01

119

Investigations of an atmospheric pressure plasma jet by optical emission spectroscopy  

Microsoft Academic Search

A plasma jet, which works under atmospheric pressure, has been developed for surface treatment. The plasma stream is generated with a dielectric barrier discharge (DBD) and a process gas of Ar flowing out into the environmental air. The DBD plasma jet features a cold gas temperature. Furthermore, the plasma stream is harmless for humans because of its low voltage. In

S. Förster; C. Mohr; W. Viöl

2005-01-01

120

Physics and chemistry in a glow dielectric barrier discharge at atmospheric pressure: diagnostics and modelling  

Microsoft Academic Search

Glow dielectric barrier discharge (GDBD) appears as an attractive solution to realise an atmospheric pressure cold plasma process suitable for all the surface treatments including thin film coatings. Such a development requires a large understanding of the GDBD physics and chemistry. The objective of this work is to contribute to that understanding. From the analysis of electrical measurements, time resolved

F. Massines; P. Ségur; N. Gherardi; C. Khamphan; A. Ricard

2003-01-01

121

Cold atmospheric plasma decontamination of the pericarps of fruit.  

PubMed

This investigation describes the inactivation by cold atmospheric plasmas of one pathogenic and three spoilage organisms on the pericarps of mangoes and melons. The operating voltage necessary for efficient microbial decontamination of fruit pericarps was first established using Escherichia coli at a concentration of 10(7) CFU/cm2 on the surface of mango. It was found that, when the plasma was sustained slightly above its breakdown voltage of 12 kV (peak to peak), no inactivation was detected when cells were plated onto tryptone soya extract agar (TSA). However, when plated onto eosin methylene blue agar, sublethal injury corresponding to approximately 1 log reduction was achieved, whereas on TSA supplemented with 4% NaCl a greater reduction of 1.5 log was revealed. When the voltage was increased by 33% to 16 kV, a reduction in cell counts of 3 log was achieved on all three plating media. Further investigations at these new operating conditions were conducted using a range of spoilage microorganisms (Saccharomyces cerevisae, Pantoea agglomerans, and Gluconacetobacter liquefaciens) all at a surface concentration of 106 CFU/cm2 on the pericarps of mango and melon. P. agglomerans and G. liquefaciens were reduced below the detection limit (corresponding to 3 log) after only 2.5 s on both fruits, whereas E. coli required 5 s to reach the same level of inactivation. S. cerevisae was the most resistant organism studied and was reduced in numbers below the detection limit after 10 s on mango and 30 s on melon. The optical emission spectra generated by the cold atmospheric plasma at both high and low operating voltages were compared in order to identify putative lethal species. It was shown that an increase in the applied voltage led to more efficient production of reactive plasma species, particularly oxygen atoms, and the production of oxygen atoms was related to the level of bacterial inactivation achieved. Production of atomic oxygen could be used as an indicator of inactivation efficiency for scaling up cold plasma systems for whole fruit. PMID:18326179

Perni, Stefano; Liu, David W; Shama, Gilbert; Kong, Michael G

2008-02-01

122

Bacillus subtilis devitalization mechanism of atmosphere pressure plasma jet  

Microsoft Academic Search

Bio-applications of atmospheric pressure plasma have been widely studied in recent years. However, the devitalization mechanisms of micro-organisms by atmosphere pressure plasma have not been clearly explained. This paper was to find the possible sterilization mechanisms and define the major sterilization factors with the atmospheric pressure plasma jet. For the sterilization target, the Bacillus subtilis was selected. In this paper,

Sanxi Deng; Cheng Cheng; Guohua Ni; Yuedong Meng; Hua Chen

2010-01-01

123

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

124

Basalt vesicularity as a measure of atmospheric pressure and palaeoelevation  

Microsoft Academic Search

THE pressure in, and thus the size of, a bubble in a lava flow is determined by the atmospheric pressure and the hydrostatic pressure of the overlying lava. If atmospheric sea-level pressure is known (or assumed), vesicle size distributions in basalt flows can thus be used as an indicator of the palaeoelevation of emplacement1. Here we show by analysis of

Dork L. Sahagian; Joseph E. Maus

1994-01-01

125

Atmospheric pressure scanning transmission electron microscopy  

SciTech Connect

Scanning transmission electron microscope (STEM) images of gold nanoparticles (2.1 nm average diameter) at atmospheric pressure have been recorded through a 0.36 mm thick mixture of CO, O2 and He. This was accomplished using a reaction cell consisting of two electron-transparent silicon nitride membranes mounted on a specially designed specimen rod. Gas flow occurred through plastic tubing from the outside of the microscope to the specimen region and back. Gold nanoparticles of a full width half maximum diameter of 1.0 nm were visible above the background noise and the achieved resolution was 0.5 nm in accordance with calculations of the beam broadening.

De Jonge, Niels [ORNL; Veith, Gabriel M [ORNL; Bigelow, Wilbur C [ORNL

2010-01-01

126

Characteristics of atmospheric pressure microwave plasma torch  

NASA Astrophysics Data System (ADS)

Atmospheric pressure microwave (2.45 GHz) plasma torch has been designed and built. The plasma optical and electrical characteristic have been investigated. The data has been compared with the kHz frequency rf torch. Electron temperature, density and gas temperatures are measured for different flow rates and for different gases. Optical emission spectrometer and ICCD camera are used to measure the argon and helium plasma characteristics and the results are compared for both designs. This Work has been supported by TUBITAK TEYDEB project no:9100036

Bozduman, Ferhat; Teke, Erdogan; Gulec, Ali; Oksuz, Lutfi

2012-10-01

127

SIMION ion optics simulations at atmospheric pressure  

SciTech Connect

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 SDS (Statistical Diffusion Simulation) user program avoids the computationally intensive issues of high collision rates by employing collision statistics to simulate the effects of millions of collisions per time step. Ion motions are simulated by a combined viscous ion mobility and random ion jumping approach. Comparison of the model predictions against measurement of Cs+ transport through room air, N2, Xe, Ar, and He collision gases in a simple drift cell at pressures from 6 Torr to 640 Torr are favorable and provide confidence that the approach is viable.

anthony d appelhans; david a dahl

2005-06-01

128

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

129

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

130

EDITORIAL Metal vapour in atmospheric-pressure arcs Metal vapour in atmospheric-pressure arcs  

Microsoft Academic Search

Metal vapour has a significant, and in some cases dominant, influence in many applications of atmospheric-pressure plasmas, including arc welding, circuit interruption and mineral processing. While the influence of metal vapour has long been recognized, it is only recently that diagnostic and computational tools have been sufficiently well-developed to allow this influence to be more thoroughly examined and understood. Some

Anthony B. Murphy

2010-01-01

131

Structure of the Pressure-Assisted Cold Denatured State of Ubiquitin  

Microsoft Academic Search

The pressure-assisted cold denatured state of ubiquitin in aqueous solution was investigated by high resolution NMR. Hydrogen exchange kinetics were measured for backbone amide protons in the cold denatured protein to determine its structure. In contrast to cold denatured ribonuclease A and lysozyme, cold denatured ubiquitin shows little persistent secondary structure. The behavior of ubiquitin supports the idea of a

David P. Nash; Jiri Jonas

1997-01-01

132

Decontamination Using a One Atmosphere Uniform Glow Discharge Cold Plasma.  

National Technical Information Service (NTIS)

Atmospheric Glow Technologies is developing an innovative mobile atmospheric plasma decon system based upon the patented one atmosphere uniform glow discharge plasma (OAUGDP) technology. This advanced system will be a deployable military protection system...

K. Kelly-Wintenberg

2002-01-01

133

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

134

Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere - Part 1: 2-D modeling in mean atmosphere  

NASA Astrophysics Data System (ADS)

In the first part of this study for revisiting the cold condensation effect on global distribution of semi-volatile organic chemicals (SVOCs), the atmospheric transport of SVOCs to the Arctic in the mid-troposphere in a mean meridional atmospheric circulation over the Northern Hemisphere was simulated by a two-dimensional (2-D) atmospheric transport model. Results show that under the mean meridional atmospheric circulation the long-range atmospheric transport of SVOCs from warm latitudes to the Arctic occurs primarily in the mid-troposphere. Although major sources are in low and mid-latitude soils, the modeled air concentration of SVOCs in the mid-troposphere is of the same order as or higher than that near the surface, demonstrating that the mid-troposphere is an important pathway and reservoir of SVOCs. The cold condensation of the chemicals is also likely to take place in the mid-troposphere over a source region of SVOCs in warm low latitudes through interacting with clouds. We demonstrate that the temperature dependent vapour pressure and atmospheric degradation rate of SVOCs exhibit similarities between lower atmosphere over the Arctic and the mid-troposphere over a tropical region. Frequent occurrence of atmospheric ascending motion and convection over warm latitudes carry the chemicals to a higher altitude where some of these chemicals may partition onto solid or aqueous phase through interaction with atmospheric aerosols, cloud water droplets and ice particles, and become more persistent at lower temperatures. Stronger winds in the mid-troposphere then convey solid and aqueous phase chemicals to the Arctic where they sink by large-scale descending motion and wet deposition. Using calculated water droplet-air partitioning coefficient of several persistent organic semi-volatile chemicals under a mean air temperature profile from the equator to the North Pole we propose that clouds are likely important sorbing media for SVOCs and pathway of the cold condensation effect and poleward atmospheric transport. The role of deposition and atmospheric descending motion in the cold condensation effect over the Arctic is also discussed.

Ma, J.

2010-08-01

135

Study of Atmospheric Pressure Abnormal Glow Discharge  

NASA Astrophysics Data System (ADS)

Atmospheric pressure abnormal glow discharge (APAGD) was carried out simply with a transformer of 1: 500 driven by a alternating current with a frequency of 50 Hz. Typical stable discharge parameters, namely voltage of 400 V to 850 V and current of 60 mA to 110 mA were measured by oscillograph. Simulation of the discharge process suggested that the stable discharge was supported by the impedance from the secondary coil of the transformer, which offered a negative feedback to prevent the discharge from turning into an arc. An interpretation was given for the oscillogram of the sinuous discharge current and square voltage. Furthermore, the electron temperature and electron density averaged in the discharge channel of APAGD were estimated.

Li, Xiang; Tang, Changjian; Dai, Xiaoyan; Yin, Yongxiang

2008-04-01

136

Protein patterning by atmospheric-pressure plasmas  

NASA Astrophysics Data System (ADS)

Low-frequency (LF) atmospheric-pressure plasma (APP) jets have been used for patterning of thin fibronectin films deposited on a silicon (Si) wafer with the use of a metal stencil mask. Since fibronectin is an adhesion protein that can be found in the extracellular matrix (ECM), a micro-patterned fibronectin film may be used for arranging living cells in a desired pattern on a surface. Removal of fibronectin from the surface by plasma application was observed by Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM). It has been found that removal of fibronectin takes place even in the location away from the direct plasma jet application spot, which indicates that desorption of fibronectin is likely to be caused by chemically reactive charge-neutral species that can diffuse away from the plasma without emitting visible light.

Ando, A.; Sayed, M. A.; Asano, T.; Tero, R.; Kitano, K.; Urisu, T.; Hamaguchi, S.

2010-06-01

137

Numerical experiments on the atmospheric response to cold Equatorial Pacific conditions ('La Nina') during northern summer.  

National Technical Information Service (NTIS)

The effect of cold conditions in the central and eastern Equatorial Pacific during Northern Summer is examined in a series of numerical experiments with the low resolution (T21) atmospheric general circulation model ECHAM2. Anomalous sea surface temperatu...

H. Storch D. Schriever K. Arpe G. W. Branstator R. Legnani

1993-01-01

138

High frequency atmospheric cold plasma treatment system for materials surface processing  

NASA Astrophysics Data System (ADS)

The paper presents a new laboratory-made plasma treatment system. The power source which generates the plasma is based on a modern half-bridge type inverter circuit working at a frequency of 4 MHz, and giving an output power of about 200 W. The inverter is fed directly from the mains voltage and features high speed protection circuits for both over voltage and over current protection, making the system light and easy to operate. The output of the inverter is connected to the resonant circuit formed by a Tesla coil and the dielectric barrier discharge plasma chamber. The plasma is generated at atmospheric pressure in argon, helium or mixtures of helium and small quantities of argon. It is a cold discharge (Tgas < 150°C) with a homogeneous structure. The plasma generates chemically active species, especially O and OH, which could be important in various applications such as the treatment and processing of materials surfaces.

Tudoran, Cristian D.; Surducan, Vasile; Anghel, Sorin D.

2012-02-01

139

Pulsed dc- and sine-wave-excited cold atmospheric plasma plumes: A comparative analysis  

NASA Astrophysics Data System (ADS)

Cold atmospheric-pressure plasma plumes are generated in the ambient air by a single-electrode plasma jet device powered by pulsed dc and ac sine-wave excitation sources. Comprehensive comparisons of the plasma characteristics, including electrical properties, optical emission spectra, gas temperatures, plasma dynamics, and bacterial inactivation ability of the two plasmas are carried out. It is shown that the dc pulse excited plasma features a much larger discharge current and stronger optical emission than the sine-wave excited plasma. The gas temperature in the former discharge remains very close to the room temperature across the entire plume length; the sine-wave driven discharge also shows a uniform temperature profile, which is 20-30 degrees higher than the room temperature. The dc pulse excited plasma also shows a better performance in the inactivation of gram-positive staphylococcus aureus bacteria. These results suggest that the pulsed dc electric field is more effective for the generation of nonequilibrium atmospheric pressure plasma plumes for advanced plasma health care applications.

Xiong, Q.; Lu, X. P.; Ostrikov, K.; Xian, Y.; Zou, C.; Xiong, Z.; Pan, Y.

2010-04-01

140

BLOOD PRESSURE AND HEART RATE RESPONSES IN MEN EXPOSED TO ARM AND LEG COLD PRESSOR TESTS AND WHOLE-BODY COLD EXPOSURE  

Microsoft Academic Search

Objectives. Comparison of the effects of different types of cold exposure on blood pressure and heart rate. Study design. Controlled laboratory study. Methods. Twenty healthy men were exposed to three different types of cold exposure: cold pressor tests for hands and feet, and a 2-h cold air exposure at an ambient temperature of +10 °C. Results. All types of cold

Ilkka Korhonen

141

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

142

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

143

Correcting for Atmospheric Pressure Loading in GPS Processing  

Microsoft Academic Search

Atmospheric pressure loading effects are calculated for more than 70 worldwide IGS permanent GPS stations using the atmospheric surface pressure data given by the ECMWF on a grid of 1o by 1o. These loading effects are then compared to timeseries of height coordinates determined by different GPS processing centers. We found high correlations between the two time series, especially for

T. VanDam; M. Brondeel; A. De Wulf

2002-01-01

144

Study of atmospheric pressure Capillary Plasma Electrode Discharge (CPED)  

Microsoft Academic Search

Atmospheric pressure plasmas, like dielectric barrier discharges (DBDs) or coronas, have long been used for a variety of industrial applications. Capillary Plasma Electrode Discharge (CPED) developed at Stevens Institute of Technology is a novel atmospheric pressure type discharge with a major potential for applications in surface cleaning, sterilization and VOC destruction. Capillary discharge is more stable, provides higher electron densities

Lukasz Moskwinski

2009-01-01

145

Simulation of a helium\\/oxygen atmospheric pressure plasma jet  

Microsoft Academic Search

Atmospheric pressure plasma jet (APPJ) has attracted a great deal of attention recently because its atmospheric pressure operation minimize the need for high cost vacuum system and thus allows a wide range of applications, e.g., surface modification, thin film synthesis, and bio-medical treatments, etc., at low cost. Although experimental works have been demonstrated extensively, along with numerical simulation using global

P.-W. Yu; F.-W. Gu; K.-C. Leou; M.-W. Wu; C.-F. Ai

2010-01-01

146

Investigation of Helium Atmospheric Pressure Plasma Jet by Schlieren Visualization  

Microsoft Academic Search

An optical schlieren system was used to visualize he- lium gas flow in ambient. Simultaneous photographing of gas flows and plasma plumes helps to reveal more details of atmospheric pressure plasma jet. Index Terms—Atmospheric pressure plasma jet (APPJ), schlieren photography.

Nan Jiang; Jinglong Yang; Feng He; Zexian Cao

2011-01-01

147

Spectral diagnosis of plasma jet at atmospheric pressure  

Microsoft Academic Search

A new approach to surface modification of materials using dielectric barrier discharge (DBD) plasma jet at atmospheric pressure is presented in this 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, whose range is from 300nm to 1000nm, were measured at different

X. L. Tang; G. Qiu; C. Li; X. P. Wang; X. P. Feng

2009-01-01

148

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

149

Corrosion Protection of Light Alloys Using Low Pressure Cold Spray  

NASA Astrophysics Data System (ADS)

Corrosion attack of aluminum- and magnesium-based alloys is a major issue worldwide. This study provides a report on the electrochemical behavior of several types of protective metal coatings obtained by low pressure cold spray (LPCS) and describes the performance of the latter's corrosion resistance properties. In this manner several metal feedstock compositions were cold sprayed on AA2024-T3 Alclad substrate. Electrochemical methods, such as open circuit potential and potentiodynamic polarization, were used in combination with materials characterization techniques to assess the performance of LPCS protective coating layers. All sprayed samples were tested in the accelerated corrosion salt spray chamber for a time period of up to 500 h to obtain corrosion kinetics data, and with specific attention being focused on the characterization of the coating's microstructural and mechanical properties. The overall conclusion of this study is that the LPCS process could be utilized to deposit corrosion protection coatings of light alloys as well as to repair aluminum and aluminum cladding structures during overhaul maintenance schedule in industry.

Dzhurinskiy, D.; Maeva, E.; Leshchinsky, Ev.; Maev, R. Gr.

2012-03-01

150

Room-temperature atmospheric pressure plasma plume for biomedical applications  

SciTech Connect

As low-temperature nonequilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little ozone is generated and the gas temperature, as measured by emission spectroscopy, remains at room temperature even after hours of operations. The plasma plume can be touched by bare hands and can be directed manually by a user to come in contact with delicate objects and materials including skin and dental gum without causing any heating or painful sensation.

Laroussi, M.; Lu, X. [Electrical and Computer Engineering Department Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23529 (United States)

2005-09-12

151

Low and atmospheric pressure plasma treatment of natural textile fibers  

Microsoft Academic Search

In this contribution we report on plasma modification of natural textile fibres, like raw wool and wool yarn and cotton wool and cotton yarn. Radiofrequency plasmas (13.56 MHz) generated in parallel plate configuration at low pressure and in dielectric barrier discharge (DBD) configuration at atmospheric pressure have been used. At low pressure the samples were treated at different times (1-30

I. Luciu; B. Mitu; V. Satulu; A. Matei; G. Dinescu

2008-01-01

152

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

153

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

154

Analysis of Sterilization Effect of Atmospheric Pressure Pulsed Plasma  

SciTech Connect

We have developed a new technology, the High Voltage Atmospheric Pressure Pulsed Plasma (HVAPPP), for bacteria killing. The aim of this paper is to present a simple device to generate plasma able to kill efficiently bacteria.

Ekem, N.; Akan, T.; Pat, S. [Eskisehir Osmangazi University, Physics department, Eskisehir (Turkey); Akgun, Y.; Kiremitci, A. [Eskisehir Osmangazi University Microbiology department, Eskisehir (Turkey); Musa, G. [National Institute for Laser Plasma and Radiation Physics, Bucharest (Romania)

2007-04-23

155

Combined barrier discharge in atmospheric-pressure air  

NASA Astrophysics Data System (ADS)

A combined (dual) barrier electric discharge in atmospheric-pressure air is investigated. The discharge is induced in a discharge chamber with two pairs of electrodes of different configurations. The electrodes are connected to two independent high voltage power supplies. The plasma-chemical synthesis of ozone was studied in atmospheric pressure air depending on the parameters of each discharge contour. The analysis was performed in terms of efficiency and practical application of a combined barrier discharge.

Andreev, V. V.; Pichugin, Yu. P.; Telegin, V. G.; Telegin, G. G.

2012-12-01

156

Preface: Subsurface, surface and atmospheric processes in cold regions hydrology  

Technology Transfer Automated Retrieval System (TEKTRAN)

This special section presents papers from three sessions at the 24th General Assembly of the International Union of Geodesy and Geophysics (IUGG), held in Perugia, Italy, in July 2007: ‘Interactions between snow, vegetation and the atmosphere’, ‘Hydrology in mountain regions’ and ‘Climate-permafrost...

157

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

158

On OH production in water containing atmospheric pressure plasmas  

NASA Astrophysics Data System (ADS)

In this paper radical production in atmospheric pressure water containing plasmas is discussed. As OH is often an important radical in these discharges the paper focuses on OH production. Besides nanosecond pulsed coronas and diffusive glow discharges, several other atmospheric pressure plasmas which are of interest nowadays have a typical electron temperature in the range 1-2 eV and an ionization degree of 10-5-10-4. These properties are quite different from the typical plasma properties known from low pressure gas discharges. In the plasma physics literature OH production is primarily ascribed to be due to electron, metastable induced or thermal dissociation of water, processes which are dominant in (low pressure) gas discharges and in combustion and hot flames. It is shown in this paper that for several atmospheric pressure plasmas also dissociative recombination can be an effective method of OH radical production. Several examples are presented in detail. This paper provides a basic framework for OH production in atmospheric pressure plasmas and shows that accurate knowledge of ne, Te, Tg, the dominant ionic species, radical and neutral species are indispensable to obtain a complete view on the chemical kinetics in these challenging complex atmospheric pressure plasmas. A few relevant plasma diagnostics together with their limitations are also briefly discussed in this context.

Bruggeman, Peter; Schram, Daan C.

2010-08-01

159

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

160

The impact of cold atmospheric plasmas on microbialy contaminated raw plant foods  

Microsoft Academic Search

A considerable body of data has been accumulated in recent years attesting to the efficacy of cold atmospheric plasmas in inactivating microorganisms on the surfaces of abiotic materials such as glass and synthetic membranes. However, one novel application for such plasmas is in microbially decontaminating foods such as fruits and vegetables which are served raw, and for which there are

D. L. Bayliss; G. Shama; M. G. Kong

2008-01-01

161

Atmospheric Pressure Plasma Jet (APPJ) and Dielectric Barrier Atmospheric Pressure Glow Discharge (DB-APGD) in Comparison  

Microsoft Academic Search

In this work two prominent types of low temperature atmospheric pressure plasma sources are compared. First, a plane-parallel 13.56 MHz RF-excited atmospheric pressure plasma jet (APPJ) operated with 2 m3\\/h helium feed gas containing 0.5 % molecular oxygen is investigated. Its stainless steel electrodes' area measures 8 x 4 cm2 and the discharge gap is 1.1 mm. The effluent leaving

S. Reuter; V. Schulz-von der Gathen; H. F. Döbele

2007-01-01

162

Effect of the atmospheric pressure on surface displacements  

Microsoft Academic Search

Atmospheric pressure variations with periods of some days and months can be considered as loading functions on the Earth's surface and can induce quasi-periodic surface deformations. The influence of such surface displacements is calculated by performing a convolution sum between the mass loading Green's functions and the local and regional barometric pressure data (geographically distribution in a 1° × 1°

H.-P. Sun; B. Ducarme; V. Dehant

1995-01-01

163

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

164

Estimating atmospheric pressure loading regression coefficients from GPS observations  

Microsoft Academic Search

The loading exerted by atmospheric pressure on the surface of the Earth causes deformations, mainly in vertical direction. Consequently, these deformations are also subject to pressure variations. At present this effect is only modeled by a few research groups in the post-processing of very long baseline interferometry (VLBI) and global positioning system (GPS) observations. As the displacements may clearly exceed

Klaus Kaniuth; Sandra Vetter

2006-01-01

165

Atmospheric pressure fluctuations and oxygen enrichment in waste tanks  

SciTech Connect

During In-Tank Precipitation (ITP) processing radiolytic decomposition of tetraphenylborate and water can produce benzene and hydrogen, which, given sufficiently high oxygen concentrations, can deflagrate. To prevent accumulations of benzene and hydrogen and avoid deflagration, continuous nitrogen purging is maintained. If the nitrogen purging is interrupted by, for example, a power failure, outside air will begin to seep into the tank through vent holes and cracks. Eventually a flammable mixture of benzene, hydrogen, and oxygen will occur (deflagration). However, this process is slow under steady-state conditions (constant pressure) and mechanisms to increase the exchange rate with the outside atmosphere must be considered. The most important mechanism of this kind is from atmospheric pressure fluctuations in which an increase in atmospheric pressure forces air into the tank which then mixes with the hydrogen-benzene mixture. The subsequent decrease in atmospheric pressure causes venting from the tank of the mixture -- the net effect being an increase in the tank`s oxygen concentration. Thus, enrichment occurs when the atmospheric pressure increases but not when the pressure decreases. Moreover, this natural atmospheric {open_quotes}pumping{close_quotes} is only important if the pressure fluctuations take place on a time scale longer than the characteristic mixing time scale (CMT) of the tank. If pressure fluctuations have a significantly higher frequency than the CMT, outside air will be forced into the tank and then out again before any significant mixing can occur. The CMT is not known for certain, but is estimated to be between 8 and 24 hours. The purpose of this report is to analyze yearly pressure fluctuations for a five year period to determine their statistical properties over 8 and 24-hour periods. The analysis also includes a special breakdown into summer and winter seasons and an analysis of 15-minute data from the SRTC Climatology Site.

Kurzeja, R.J.; Weber, A.H.

1993-07-01

166

Vapor Pressure of Fluids in High-Pressure Gas Atmospheres.  

National Technical Information Service (NTIS)

As part of the investigation of the critical parameters in the combustion of hydraulic fluids, experiments were conducted to verify the accuracy of the Poynting equation which predicts the effect of inert gas pressure upon the vapor pressure of a liquid. ...

D. R. Ventriglio R. W. McQuaid

1967-01-01

167

RF-powered atmospheric pressure plasma jet for surface treatment  

NASA Astrophysics Data System (ADS)

Atmospheric pressure plasma jet (APPJ) was developed for decontamination purposes. Features of the device are ability to work with various feed-gases at the atmospheric pressure in several gas-flow, frequency and current-voltage regimes. LabVIEW virtual measurement sub-system for monitoring and measurement process through subsequent setting of electrical and gas-flow parameters (digital control of flow-meters), conditioning and amplification of electrical signals and collection of the data from peripheral measuring devices was applied. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

Paw?at, Joanna; Samo?, Rados?aw; Stryczewska, Henryka D.; Diatczyk, Jaros?aw; Gi?ewski, Tomasz

2013-02-01

168

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

169

Growth of wheat under one tenth of the atmospheric pressure  

Microsoft Academic Search

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

D. Massimino; M. André

1999-01-01

170

Attenuation of microwaves propagating through parallel-plate helium glow discharge at atmospheric pressure  

SciTech Connect

The experimental study of microwave-plasma interaction has been performed to demonstrate the transmission and attenuation of microwaves in atmospheric pressure glow discharge plasma. The cold-collisional plasma produced at atmospheric pressure can absorb the microwave energy because of its complex dielectric constant. The microwave of 10 GHz frequency was launched into the plasma and attenuation was measured as a function of electron plasma density, plasma thickness, electron-neutral collision frequency, etc. It was observed that the attenuation significantly depends on electron plasma density and thickness. The microwave attenuation measurement was also used as a diagnostic to estimate electron plasma density. It was validated by optical emission spectroscopic measurements with helium line intensity ratio method. Both the methods show good agreement.

Srivastava, A. K.; Prasad, G.; Atrey, P. K.; Kumar, Vinay [Institute for Plasma Research, Bhat, Near Indira Bridge, Gandhinagar, Gujarat 382428 (India)

2008-02-01

171

Eradication of Bacterial Biofilms Using Atmospheric Pressure Non-Thermal Plasmas  

NASA Astrophysics Data System (ADS)

Bacterial biofilms are ubiquitous in natural and clinical settings and form a major health risk. Biofilms are recognised to be the predominant mode of bacterial growth, and are an immunological challenge compared to planktonic bacteria of the same species. Eradication of biofilms with atmospheric pressure plasma jets is investigated. Cold non-equilibrium plasmas, operated at ambient atmospheric pressure and temperature, are efficient sources for controlled energy transport through highly reactive neutrals (e.g. ROS, RNS), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. A focused panel of clinically significant biofilms, including Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Bacillus cereus, are exposed to various plasma jet configurations operated in helium and oxygen mixtures. Viability of surviving cells was determined using both standard plate counting method and XTT viability assay. These are correlated with measurements and simulations of relevant reactive plasma species.

Yousef Alkawareek, Mahmoud; Gilmore, Brendan; Gorman, Sean; Algwari, Qais; Graham, William; O'Connell, Deborah

2011-11-01

172

Cold ion atmospheric plasma jets for living tissue treatment  

NASA Astrophysics Data System (ADS)

Recently a great attention is attracted to the creation of the cold plasma jets and their interaction with living tissue. The plasma gun operating on helium and equipped with high-voltage resonant transformer is designed. Long nondivergent plasma jets with length more than 5 cm and diameter 1-2 mm are obtained. The measured electrical current in the plasma jet indicates that the plasma jet is discontinuous and represents a series of propagating plasma bundles (two bundles per driving high voltage period) with peak current up to few hundred mA. The exposition of the living tissue (fibroblast cells and PEM cells) to the helium plasma jet causes an immediate detachment of part of the cells from their matrix in the case of direct contact of the jet with cell culture. In addition, it was found that migration velocity inside of the treated region significantly decreases in the case of treatment through the thin layer of the protecting media covering the cell culture.

Shashurin, Alexey; Keidar, Michael; Stepp, Mary Ann

2008-11-01

173

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

174

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

Microsoft Academic Search

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

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

2010-01-01

175

Atmospheric Pressure Chemical Vapor Deposition of Titanium Nitride  

NASA Astrophysics Data System (ADS)

Titanium nitride (TiN) is a technologically important material due to its chemical inertness, high melting point, hardness, and electrical and optical properties. The low resistivity and chemical inertness make TiN the material of choice for diffusion barriers in microelectronic applications. Thin films (<800A) of TiN were grown by Atmospheric Pressure Chemical Vapor Deposition (APCVD) from tetrakis(dimethylamido) titanium (TDMAT) or tetrakis(diethylamido) titanium (TDEAT) with and without ammonia. Depositions were conducted under cold wall reactor and laminar flow conditions in a belt furnace at low temperatures (190^circ C-420^circC). Films were characterized by four point probe, Rutherford Backscattering, Forward Recoil, and X-Ray Photoelectron Spectroscopies. Films grown from TDMAT and TDEAT in the absence of ammonia were substoichiometric (N/Ti < 0.76), highly resistive (rho > 2.2 times 10^4 muOmega-cm), and contained carbon (C/Ti = 0.15-0.45), oxygen (O/Ti = 0.7-1.3), and hydrogen. TDMAT was more reactive than TDEAT, depositing films at lower temperatures and lower ammonia concentrations. TiN deposition rates ranged from 10A/min (280^ circ, TDEAT) to 190A/min (420^ circC, TDMAT) in the absence of ammonia. Film stoichiometries improved dramatically with the addition of ammonia (NH_3/TDMAT >=q 1; NH_3/TDEAT >=q 4). N/Ti ranged from 0.9-1.1, increasing with the ammonia concentration. Oxygen and carbon concentrations fell to 0.5 and <0.1 respectively, relative to the titanium content. Nitrogen, oxygen, and carbon concentrations were insensitive to temperature when ammonia was coreacted with the metal precursor. Hydrogen concentration continued to fall with increasing ammonia partial pressure. Film growth rates (220-300 A/min) were only weakly dependent on temperature or ammonia concentration, except for TDMAT at 420^circC. Ammonia reduced the film growth rate at these conditions. Lowest resistivities were obtained at 370^circ under high ammonia concentrations (NH_3 /TDMAT = 26, rho = 1500 muOmega-cm; NH_3/TDEAT = 110, rho = 660 mu Omega-cm). Though less reactive, TDEAT had a higher conversion rate of titanium atoms (gas phase)/titanium atoms (deposited film) of 35% than TDMAT (10%), probably due to excessive dust formation from TDMAT. Preliminary conformality measurements suggest that TDEAT films have better step coverage than films from TDMAT.

Musher, Joshua N.

176

Atmospheric Pressure Wave from an Explosion  

Microsoft Academic Search

PRESSURE waves were obtained from one of two explosions set off at White Sands Missile Range (33° 27' 1ST., 106° 34' W.; elevation 4,900 ft. above mean sea-level), New Mexico. The first explosion occurred at 1100 p.m. M.S.T., October 28, 1965, and the second at 1100 a.m. M.S.T., November 2, 1965. These explosions were identical shots of 10 tons of

Bhartendu; R. McCrory

1966-01-01

177

Dynamical Downstream Modulation of the eastern North Pacific Atmospheric River Activity by East Asian Cold Surge  

NASA Astrophysics Data System (ADS)

East Asian cold surge (EACS) is an efficient mechanism transporting cold and dry air from Siberia to the east coast of the Eurasian continent. Extratropical cyclone genesis, thus the amplitude of the upper level, high-frequency baroclinic disturbances over the east coast are immediately enhanced as the cold air approaches. Utilizing a newly developed algorithm for atmospheric river detection, our study reveals that the occurrence probability of atmospheric rivers over the eastern North Pacific near the west coast of North America is significantly modulated by EACS. In particular, this dynamical downstream modulation goes through two stages where high-frequency, baroclinic disturbances propagating northeastward contributes to the formation of atmospheric rivers in the Gulf of Alaska, and low-frequency, barotropic disturbances developed following the passage of high-frequency disturbances play a more important role in organizing extreme moisture transport and atmospheric rivers along the west coast of U.S. The modulation mechanism discussed above is successfully reproduced in a high-resolution GCM initialized at the time of the peak of EACS, suggesting EACS and its dynamical triggers as potential source of predictability for the winter extreme precipitation events in the western U.S.

Jiang, T.; Deng, Y.; Chen, X.

2011-12-01

178

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

179

Plant adaptation to low atmospheric pressures: potential molecular responses.  

PubMed

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. PMID:11987308

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

2002-01-01

180

Long term properties of monthly atmospheric pressure fields  

NASA Astrophysics Data System (ADS)

We assess the statistical properties of atmospheric pressure time series retrieved from a large database of monthly records. We analyze the short and long term properties of the time series including possible trends, persistence and antipersistence. We also analyze times series of climatic indices which are based on the atmospheric pressure fields, such as the North Atlantic oscillation index and the El Niño-Southern Oscillation index. Acknowledgment: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided financial support for the participation of the students in the Assembly.

Giannoulis, S.; Ioannou, C.; Karantinos, E.; Malatesta, L.; Theodoropoulos, G.; Tsekouras, G.; Venediki, A.; Dimitriadis, P.; Papalexiou, S. M.; Koutsoyiannis, D.

2012-04-01

181

Atmospheric pressure photoionization using tunable VUV synchrotron radiation  

NASA Astrophysics Data System (ADS)

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

Giuliani, A.; Giorgetta, J.-L.; Ricaud, J.-P.; Jamme, F.; Rouam, V.; Wien, F.; Laprévote, O.; Réfrégiers, M.

2012-05-01

182

Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition  

NASA Astrophysics Data System (ADS)

An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O2 plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O2 plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O2 (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Wang, Xing-Quan; Lv, Guo-Hua; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

2012-07-01

183

Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition  

SciTech Connect

An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O{sub 2} plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O{sub 2} plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O{sub 2} (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

Chen Wei; Huang Jun; Wang Xingquan; Lv Guohua; Zhang Guoping [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Du Ning; Liu Xiaodi; Guo Lihong [Department of Oral Biology, Peking University School and Hospital of Stomatology, 100080 Beijing (China); Yang Size [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Aeronautics, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005 (China)

2012-07-01

184

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

185

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

186

Deactivation of Enterococcus Faecalis Bacteria by an Atmospheric Cold Plasma Brush  

NASA Astrophysics Data System (ADS)

An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed and used to treat enterococcus faecalis bacteria. The results show that the efficiency of the inactivation process by helium plasma is dependent on applied power and exposure time. After plasma treatments, the cell structure and morphology changes can be observed by scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Lv, Guo-Hua; Wang, Xing-Quan; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

2012-07-01

187

Alternating-current glow and pseudoglow discharges in atmospheric pressure  

Microsoft Academic Search

Stabilization and control of alternating-current glow and pseudoglow discharges have been studied in atmospheric pressure static air and methane flow gas by a pin-to-pin configuration. The electrode configuration and input power control the amplitude and duration of the discharge current and current pulses. Glow and pseudoglow discharges have been applied to the methane conversion.

Yun Yang

2003-01-01

188

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

189

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

190

VUV emission from dielectric surface flashover at atmospheric pressure  

Microsoft Academic Search

Spectroscopic measurements in the vacuum ultraviolet (VUV) regime are difficult to make due to extremely large absorption of VUV radiation in most materials. This paper describes an experimental setup designed for studying the optical emission during pulsed surface flashover for the wavelength range between 115 nm to 180 nm at atmospheric pressures with a focus on the scheme used to

G. Rogers; A. Neuber; G. Laity; J. Dickens; K. Frank; T. Schramm

2009-01-01

191

Repetitive nanosecond glow discharge in atmospheric pressure air  

Microsoft Academic Search

Nonequilibrium, weakly ionized plasmas are widely used in the industry, but they are restricted to the domain of continuous discharges at low gas pressure or with specialty gases because of stability and power budget constraints. In this study, repetitively pulsed discharges were investigated as a way to decrease the power budget of atmospheric air plasmas by several orders of magnitude

Denis Packan

2004-01-01

192

Ice Shelf Elevation Changes due to Atmospheric Pressure Variations  

Microsoft Academic Search

Floating ice shelves undergo vertical motion as a result of the response of the underlying ocean to changes in atmospheric pressure (Pair). This response is known as the inverse barometer effect (IBE). Open-ocean measurements of Pair and sea level agree with the theoretical response of 1 cm per millibar for low frequency variability of Pair. Here we demonstrate, using simultaneous

L. Padman; M. King; H. A. Fricker

2002-01-01

193

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

194

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

195

Investigation on Spurt Length of Atmospheric-Pressure Plasma Jets  

Microsoft Academic Search

Three kinds of electrode configurations are employed for studying the spurt length of atmospheric-pressure plasma jets (APPJs). The influences of Ar flow rate, applied voltage, and electrode width on APPJ length are investigated. It is found that, for all the electrode configurations, the maximal length of the APPJ is achieved at 3 L\\/min of flow rate. With the increase of

Xian-Jun Shao; Guan-Jun Zhang; Jiang-Yang Zhan; Hai-Bao Mu

2011-01-01

196

Chemical machining of Zerodur material with atmospheric pressure plasma jet  

Microsoft Academic Search

The material of Zerodur is widely used in high performance optics because of its excellent thermal stability characteristics. This paper deals with the development of an APPJ (Atmospheric Pressure Plasma Jet) chemical machining process for defect free and high efficiency machining of Zerodur. The APPJ chemical machining mechanism for multi-phase multi-composite materials is presented. The chemical property of the plasma

Y. X. Yao; B. Wang; J. H. Wang; H. L. Jin; Y. F. Zhang; S. Dong

2010-01-01

197

Development of Atmospheric Pressure Plasma Jet with Slit Nozzle  

Microsoft Academic Search

A wide flame atmospheric pressure plasma jet has been developed by using a slit nozzle for large area treatment of surfaces. The width of the plasma treated surfaces has been broadened to more than 5 times that obtained by conventional nozzle. The proper function of the slit nozzle towards surface treatment is confirmed by evaluating contact angles of water on

Nobuaki Oshima; Ryuji Takada; Yusuke Kubota; Petros Abraha; Tamio Hara

2011-01-01

198

Electrodeless microwave plasma-torch at atmospheric pressure  

Microsoft Academic Search

Summary form only given. Increasing environmental awareness and regulation have motivated research into new methods to remediate toxins from atmospheric pressure gas streams. Plasma remediation was identified as a promising technology treating contaminated gas streams and air. Plasma remediation of toxic gas streams from mobile emitting sources (i.e., Nox, Sox, soot emission from diesel truck engines) and cleaning processes (i.e.,

Y. C. Hong; H. S. Uhm

2001-01-01

199

Underground cavern storage for liquefied gases near atmospheric pressure  

Microsoft Academic Search

An underground chamber is described for storing liquid gases at substantially atmospheric pressure and cryogenic temperatures. An inclined adit has its upper end at ground level and its lower end suspends into a rock-enclosed cavern. Means are provided at the adit for sealing the cavern from the passage of liquid or vapor into or out of the cavern. Sealing means

A. R. Khan; B. E. Eakin; P. J. Anderson

1968-01-01

200

A refinement for the Rayleigh radiance computation with variation of the atmospheric pressure  

Microsoft Academic Search

The Rayleigh scattering radiance at the top of the atmosphere (TOA) depends on the surface atmospheric pressure. In processing the Coastal Zone Color Scanner (CZCS) imagery, Gordon et al. (Applied Optics, 27, 862–871, 1988) developed a simple formula to account for the Rayleigh radiance changes with the variation of the surface atmospheric pressure. For the atmospheric pressure changes within ±3%,

Menghua Wang

2005-01-01

201

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

202

Ir/thz Double Resonance Signatures at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

IR/THz double resonance (DR) spectroscopy, historically used to investigate molecular collision dynamics and THz molecular lasers at low pressures (< 1 Torr), shows promise for trace gas remote sensing at atmospheric pressure. Molecular specificity is obtained through the rare coincidence(s) between molecule-specific ro-vibrational energy levels and CO2 laser lines. The resulting molecule-specific, DR-induced, THz spectroscopic signatures strongly depend on the type of ro-vibrational transition involved (P, Q, or R), the type of vibrational level excited (stretching or bending), and the molecular mass. To illustrate these sensitivities, calculated DR spectra of prototypical molecules such as methyl fluoride, methyl chloride, and methyl cyanide will be discussed. Although atmospheric pressure broadening obfuscates pure rotational spectra, we show how it can enhance the DR signature in two ways: by relaxing the pump coincidence requirement and by adding the DR signatures of multiple nearby transitions. We will present estimates of this enhancement, including cases where the coincidences that produce the strongest DR signatures at atmospheric pressure do not exist at low pressures.

Phillips, Dane J.; Tanner, Elizabeth A.; Everitt, Henry O.; Medvedev, Ivan R.; Neese, Christopher F.; Holt, Jennifer; De Lucia, Frank C.

2010-06-01

203

Quality characteristics of the radish grown under reduced atmospheric pressure  

NASA Astrophysics Data System (ADS)

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

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

204

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

205

Calculating Low Pressure Chemical Activation Atmospheric Hydrocarbon Synthesis Rates  

NASA Astrophysics Data System (ADS)

The formation of larger hydrocarbons, polyacetylenes, aromatics, and nitriles in the reducing atmospheres of the outer planets and moons occurs by recombination and addition reactions of smaller fragments at low temperatures and pressures, difficult to reach in the laboratory. However, because C-C bonds are usually weaker than C-H bonds, cleavage reactions can occur which interrupt this synthesis. The competing dissociation and recombination channels in these chemical activation reactions will be energy and pressure dependent. (Similar competition can occur during photolysis.) The rate constants can be determined computationally using statistical rate theory with parameters available from experiments and quantum calculations. We have applied this approach to generate temperature and pressure dependent rate constant expressions for several reactions that help determine atmospheric concentrations of larger hydrocarbon species in jovian atmospheres. Attention must be paid to isomers and H tunneling. Examples include: H + C3H7 -> CH3 + C2H5 C2H3 + C2H5 -> C4H8, H + C4H7, or CH3 + C3H5 (allyl isomer) H + C3H5 -> C3H6 or CH3 + C2H3 CH3 + CN -> H + CH2CN In addition, if photolysis is followed by internal conversion of electronic energy to vibrationally excited ground state molecules, the same approach may apply to computing C-C scission product yields. Product experiments to test this are underway. Research supported by grants from the NASA Outer Planets Research Program and Planetary Atmospheres Program.

Smith, Gregory P.

2008-09-01

206

Radiative and Dynamical Feedbacks Over the Equatorial Cold-Tongue: Results from Seven Atmospheric GCMs  

SciTech Connect

The equatorial Pacific is a region with strong negative feedbacks. Yet coupled GCMs have exhibited a propensity to develop a significant SST bias in that region, suggesting an unrealistic sensitivity in the coupled models to small energy flux errors that inevitably occur in the individual model components. Could this 'hypersensitivity' exhibited in a coupled model be due to an underestimate of the strength of the negative feedbacks in this region? With this suspicion, the feedbacks in the equatorial Pacific in seven atmospheric GCMs (AGCMs) have been quantified using the interannual variations in that region and compared with the corresponding calculations from the observations. The seven AGCMs are: the NCAR CAM1, the NCAR CAM2,the NCAR CAM3, the NASA/NSIPP Atmospheric Model, the Hadley Center Model, the GFDL AM2p10, and the GFDL AM2p12. All the corresponding coupled runs of these seven AGCMs have an excessive cold-tongue in the equatorial Pacific. The net atmospheric feedback over the equatorial Pacific in the two GFDL models is found to be comparable to the observed value. All other models are found to have a weaker negative net feedback from the atmosphere--a weaker regulating effect on the underlying SST than the real atmosphere. A weaker negative feedback from the cloud albedo and a weaker negative feedback from the atmospheric transport are the two leading contributors to the weaker regulating effect from the model atmosphere. All models overestimate somewhat the positive feedback from water vapor. These results confirm the suspicion that an underestimate of negative feedbacks from the atmosphere over the equatorial Pacific region is a prevalent problem. The results also suggest, however, that a weaker regulatory effect from the atmosphere is unlikely solely responsible for the 'hypersensitivity' in all models. The need to validate the feedbacks from the ocean transport is therefore highlighted.

Sun, D; Zhang, T; Covey, C; Klein, S; Collins, W; Kiehl, J; Meehl, J; Held, I; Suarez, M

2005-01-04

207

Cryogenic Pressure Calibration Facility Using a Cold Force Reference  

Microsoft Academic Search

Presently various commercial cryogenic pressure sensors are being investigated for installation in the LHC collider, they will eventually be used to assess that the magnets are fully immersed in liquid and to monitor fast pressure transients. In the framework of this selection procedure a cryogenic pressue calibration facility has been designed and built; it is based on a cryogenic primary

T Bager; J Casas-Cubillos; L Métral

1999-01-01

208

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

209

Effects of Gas Pressure of Cold Spray on the Formation of Al-Based Intermetallic Compound  

Microsoft Academic Search

In this paper, postannealing of cold-sprayed (CDGS) coatings for intermetallic compounds (IMC) in the matrix at low temperature\\u000a and dependences of types and dispersion characteristics of intermetallic compounds on spraying pressure condition were investigated.\\u000a The pressure prior to entering the gas heater was fixed at 0.7, 1.5, and 2.5 MPa. The relatively soft Al has been coated at\\u000a low gas pressure

H. Lee; H. Shin; K. Ko

2010-01-01

210

Dynamics behavior of homogeneous dielectric barrier discharge at atmospheric pressure  

SciTech Connect

An experimental study on the dynamics behavior of homogeneous dielectric barrier discharge (HDBD) at atmospheric pressure is described in this paper. Two kinds of discharge mode, glow and Townsend discharge modes, can be easily identified according to the differential conductivity of current-voltage relationship in the ascent stage of discharge current for the atmospheric HDBD. A (three-dimensional) 3D phase space made by discharge current, gas gap voltage, and charge density of dielectric-plate surface was utilized in the study. By projecting the discharge evolution trajectory in the 3D space, the 3D trajectory of multiple current peaks discharge in atmospheric helium shows a limited cycle with convolutions and undergoes a series of bifurcation process; however, the 3D trajectory of atmospheric N{sub 2} HDBD is a limited cycle without any convolution and bifurcation process. In addition, the first ionization coefficient of working gas plays a key role to determine the discharge mode of atmospheric HDBD, the transition of discharge mode and the dynamics stability of atmospheric HDBD.

Zhang Yan [School of Mechanical and Power Engineering, Henan Polytechnic University, Henan 454000 (China); Gu Biao [State Key Laboratory for Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China); Wang Wenchun; Wang Dezhen; Peng Xuwen [State Key Laboratory for Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2009-07-15

211

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

212

Occurrence of shallow cold flows in the winter atmospheric boundary layer of interior of Alaska  

NASA Astrophysics Data System (ADS)

During winters, the absence of solar radiation combined with clear skies and weak synoptic forcing enables cold pooling in the complex topographic basins of interior Alaska. Under these conditions, shallow, small-scale cold flows originating within, or flowing from, north-facing semi-enclosed basins are able to penetrate the frigid atmospheric boundary layer (ABL) of the open south-facing basins. This paper introduces the Winter Boundary Layer Experiment carried out during three consecutive periods in Fairbanks (2009-2011) and examines observational results illustrating the changes in the mean and turbulent state of the ABL during the occurrence of shallow flows. Observations introduced here demonstrate that during flow penetration, surface layer stratification is destroyed allowing mixing and thermal stabilization of the basin cooling regime. Evidence of upper level ABL thermal turbulence related to shear driven flow is introduced and discussed. Basin-scale turbulent heat fluxes are shown to reach -20 Wm-2 during flow occurrence.

Fochesatto, Gilberto J.; Mayfield, John A.; Starkenburg, Derek P.; Gruber, Matthew A.; Conner, James

2013-10-01

213

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

214

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

215

Atmospheric pressure loading effects on Global Positioning System coordinate determinations  

SciTech Connect

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.

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

1994-12-01

216

ECD-like peptide fragmentation at atmospheric pressure  

PubMed Central

Fragmentation of multiply-charged peptide ions via interaction with products of gas discharge at atmospheric pressure conditions was studied using ion mobility separation – fragmentation cell - linear ion trap mass spectrometer. The observed fragmentation spectra mainly consisted of c- type ions that are specific to electron capture dissociation. Experiments with different gases flowing through the discharge and different discharge polarities suggested that fragmentation proceeds via capture of free electrons. Fragmentation of a model phosphorylated peptide using this technique produced c- type fragments with an intact phosphorylation group. High field asymmetric waveform ion mobility separation of a peptide mixture prior to the fragmentation cell demonstrated the feasibility of conducting MS/MS-like experiments at atmospheric pressure conditions.

Berkout, Vadym D.; Doroshenko, Vladimir M.

2012-01-01

217

Removal of paper microbial contamination by atmospheric pressure DBD discharge  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

218

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

219

The study of atmospheric pressure plasma for surface cleaning  

Microsoft Academic Search

In this study, capillary dielectric-covered dielectric barrier discharge was used to generate atmospheric pressure plasmas. The effect of various gas combinations such as He+O2, (He+O2)\\/Ar, and (He+O2)\\/SF6 was studied with respect to the changes in contact angle, surface energy and photoresist etch rate (ER). By adding a small percentage of O2 (40 sccm) to He (4 slm), we observed the

C. H. Yi; Y. H. Lee; G. Y. Yeom

2002-01-01

220

Capacitively Coupled Microplasma Source on a Chip at Atmospheric Pressure  

Microsoft Academic Search

A small-scale and low-power 13.56 MHz capacitively coupled plasma is generated in a capillary, whose cross section is 65--500× 500--5000 mum, on a quartz chip of 20× 20 mm at atmospheric pressure. The capillary is sandwiched between parallel-plate electrodes which are externally located on a chip. A pi-type matching network is miniaturized and appropriately designed to satisfy the resonance condition

Hiroyuki Yoshiki; Yasuhiro Horiike

2001-01-01

221

Atmospheric pressure plasma processing with microstructure electrodes and microplanar reactors  

Microsoft Academic Search

Atmospheric pressure plasmas can be generated, if the distance between the plasma generating electrodes is in the range of 100 ?m, and radio-frequencies of 13.56 or 27.12 MHz are applied. Such small dimensioned plasmas are only of interest for industrial plasma applications if larger areas can be processed. It will be shown that both with microstructure electrodes as with microplanar-reactor,

H. Schlemm; D. Roth

2001-01-01

222

RF from two pulse laser plasmas in atmospheric pressure gas  

Microsoft Academic Search

Summary form only given. We have measured the production of RF produced by a mode-locked (M-L) CO2 laser (100 mJ macro pulse, 3 ns pulselets @ 25 Mhz) focused onto a target of copper in a background of atmospheric pressure N2 and He. Prior to the arrival of the M-L laser pulse, a small (few mm to cm) “vacuum bubble”

G. K. Chawla

1997-01-01

223

Beta-type Stirling engine operating at atmospheric pressure  

Microsoft Academic Search

In this study, a beta-type Stirling engine, with a 192 cc total swept-volume, was manufactured and its performance tested at atmospheric pressure. The hot-source temperature is chosen as a fundamental parameter of the experimental study. Experiments were performed with an electrical heater at 800, 900 and 1000 °C temperatures. Torque and output-power variations were obtained for different engine speeds. The

Serdar Yucesu; Tolga Topgul; Melih Okur

2005-01-01

224

Ice-shelf elevation changes due to atmospheric pressure variations  

Microsoft Academic Search

The inverse barometer effect (IBE) is the isostatic response of ocean surface height to changes in atmospheric pressure (Pair) at a rate of about 1cm hPa-1. The IBE is a significant contributor to variability of ice-shelf surface elevation (etaice), as we demonstrate with simultaneous global positioning system measurements of etaice and local measurements of Pair from the Amery, Brunt and

Laurie Padman; Matt King; Derek Goring; Hugh Corr; Richard Coleman

2003-01-01

225

Direct-current glow discharges in atmospheric pressure air plasmas  

Microsoft Academic Search

Investigations have been conducted to experimentally validate the mechanisms of ionization in two-temperature atmospheric pressure air plasmas in which the electron temperature is elevated with respect to the gas temperature. To test a predicted S-shaped dependence of steady-state electron number density on the electron temperature and its macroscopic interpretation in terms of current density versus electric field, direct-current (dc) glow

Lan Yu; Christophe O. Laux; Denis M. Packan; Charles H. Kruger

2002-01-01

226

Oxidation of Pd(553): From ultrahigh vacuum to atmospheric pressure  

Microsoft Academic Search

The oxidation of a vicinal Pd(553) surface has been studied from ultrahigh vacuum (UHV) to atmospheric oxygen pressures at elevated sample temperatures. The investigation combines traditional electron based UHV techniques such as high resolution core level spectroscopy, low-energy electron diffraction, scanning tunneling microscopy with in situ surface x-ray diffraction, and ab initio simulations. In this way, we show that the

R. Westerström; J. Gustafson; A. Resta; A. Mikkelsen; J. N. Andersen; E. Lundgren; N. Seriani; F. Mittendorfer; M. Schmid; J. Klikovits; P. Varga; M. D. Ackermann; J. W. M. Frenken; N. Kasper; A. Stierle

2007-01-01

227

Spatiotemporal behavior of a dielectric capillary atmospheric pressure plasma jet  

Microsoft Academic Search

We have studied an atmospheric pressure plasma jet utilizing time- and space-resolved emission spectroscopy by flowing helium\\/argon gas mixtures through a cylindrical glass capillary energized using a deltatrise ˜ 15 ns high voltage pulse. Emission measurements from Ar 2p1--1s2 were acquired from both the inner capillary DBD and the outer plasma jet. Just outside the capillary, the jet emission was

Brian Sands; Biswa Ganguly; Kunihide Tachibana

2007-01-01

228

Materials processing with atmospheric-pressure plasma jets  

Microsoft Academic Search

Summary form only given. Atmospheric-pressure plasma jets can be used for a wide range of materials processing applications, including surface cleaning and modification, selective etching, and thin-film deposition. The plasma source consists of two closely spaced electrodes through which helium and other gases flow (O2, CF4, etc.). A variety of electrode configurations can be used, and the source is suitable

R. Hicks; J. Jeong; S. Babayan; A. Schuetze; Jaeyoung Park; H. Herrmann; I. Henins; G. Selwyn

1998-01-01

229

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

230

Production of titanium dioxide powders by atmospheric pressure plasma jet  

Microsoft Academic Search

TiO2 powders have been successfully synthesized by atmospheric pressure plasma jet (APPJ), which operates by feeding air between two coaxial electrodes that are driven by a 20.8kHz power source. Tetrachloride titanium is mixed with the effluent of the plasma jet in deferent regions to produce TiO2 powders. The synthesized samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy

Zhongwei Liu; Qiang Chen; Zhengduo Wang; Lizhen Yang; Chuanyue Wang

2011-01-01

231

Spinel lithium manganese oxide synthesized under a pressurized oxygen atmosphere  

Microsoft Academic Search

Spinel lithium manganese oxide was synthesized via co-precipitation. The prepared lithium manganese oxide powder was further heated at 700°C for 15h under pressurized (3bar) oxygen atmosphere. The resultant exhibited a highly crystalline cubic spinel phase with space group Fd3m, as confirmed by X-ray diffraction. The spinel compound exhibited a slightly smaller lattice constant than a conventional spinel compound, even though

Ki-Soo Lee; Seung-Taek Myung; Hun-Gi Jung; Jung Kyoo Lee; Yang-Kook Sun

2010-01-01

232

Thin film deposition on powder surfaces using atmospheric pressure discharge  

SciTech Connect

The deposition of SiOx containing films on NaCl and KBr particles in dielectric barrier discharge under atmospheric pressure was investigated. As precursor hexamethyldisiloxane (HMDSO) and tetraethoxysilane (TEOS) in argon-oxygen gas mixtures were used. The deposited layers were studied by means of light microscopy, SEM and XPS investigations. The particles could be completely covered by SiOx. With increasing oxygen content in the coating the carbon content decreases.

Brueser, V.; Haehnel, M.; Kersten, H. [Institute for Low Temperature Plasma Physics, F.-L.-Jahn-Str.19, 17489 Greifswald (Germany)

2005-10-31

233

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

234

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

235

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

236

Infrared laser ablation atmospheric pressure photoionization mass spectrometry.  

PubMed

In this paper we introduce laser ablation atmospheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass spectrometry. In LAAPPI the analytes are ablated from water-rich solid samples or from aqueous solutions with an infrared (IR) laser running at 2.94 ?m wavelength. Approximately 12 mm above the sample surface, the ablation plume is intercepted with an orthogonal hot solvent (e.g., toluene or anisole) jet, which is generated by a heated nebulizer microchip and directed toward the mass spectrometer inlet. The ablated analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 eV vacuum ultraviolet krypton discharge lamp. The effect of operational parameters and spray solvent on the performance of LAAPPI is studied. LAAPPI offers ~300 ?m lateral resolution comparable to, e.g., matrix-assisted laser desorption ionization. In addition to polar compounds, LAAPPI efficiently ionizes neutral and nonpolar compounds. The bioanalytical application of the method is demonstrated by the direct LAAPPI analysis of rat brain tissue sections and sour orange (Citrus aurantium) leaves. PMID:22242626

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

2012-01-19

237

Atmospheric pressure thermospray ionization using a heated microchip nebulizer.  

PubMed

When a standard atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI) ion source is used without applying the corona discharge or photoirradiation, atmospheric pressure thermospray ionization (APTSI) of various compounds can be achieved. Although largely ignored, this phenomenon has recently gained interest as an alternative ionization technique. In this study, this technique is performed for the first time on a miniaturized scale using a microchip nebulizer. Sample ionization with the presented microchip-APTSI (microAPTSI) is achieved by applying only heat and gas flow to a nebulizer chip, without any other methods to promote gas-phase ionization. To evaluate the performance of the described microAPTSI setup, ionization efficiency for a set of test compounds was monitored as the microchip positioning, temperature, nebulizer gas flow rate, sample solution composition, and solvent flow rate were varied. The microAPTSI mass spectra of the test compounds were also compared to those obtained with ESI and APCI. The microAPTSI produces ESI-like spectra with low background noise, favoring the formation of protonated or deprotonated molecules of compounds that are ionizable in solution. Multiple charging of peptides without in-source fragmentation was also observed. Unlike ESI, however, the microAPTSI source can tolerate the presence of mobile phase additives like trifluoroacetic acid (TFA) without significant ion suppression. The microAPTSI source can be used with standard mass spectrometer ion source hardware, being a unique alternative to the present interfacing techniques. PMID:19760642

Keski-Rahkonen, Pekka; Haapala, Markus; Saarela, Ville; Franssila, Sami; Kotiaho, Tapio; Kostiainen, Risto; Auriola, Seppo

2009-10-30

238

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

239

Separation of VUV\\/UV photons and reactive particles in the effluent of a He\\/O2 atmospheric pressure plasma jet  

Microsoft Academic Search

Cold atmospheric pressure plasmas can be used for treatment of living tissues or for inactivation of bacteria or biological macromolecules. The treatment is usually characterized by a combined effect of UV and VUV radiation, reactive species and ions. This combination is usually beneficial for the effectiveness of the treatment but it makes the study of fundamental interaction mechanisms very difficult.

S. Schneider; J.-W. Lackmann; F. Narberhaus; J. E. Bandow; B. Denis; J. Benedikt

2011-01-01

240

Multi-atmospheric pressure ionisation interface for liquid chromatography–mass spectrometry  

Microsoft Academic Search

We describe the structure of a multi-atmospheric pressure ionisation (multi-API) interface for liquid chromatography–mass spectrometry (LC–MS). This interface includes five modes of atmospheric pressure spray with electron impact ionisation (APEI), atmospheric pressure chemical ionisation (APCI), atmospheric pressure spray ionisation (APSI), electrospray ionisation (ESI) and sonic spray ionisation (SSI). This LC–MS system was realised by developing an APEI interface which resembles

Minoru Sakairi; Yoshiaki Kato

1998-01-01

241

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

242

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

Microsoft Academic Search

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 (?10 Pa), rapid (?20 min) fluctuations in atmospheric pressure were an important driving force for soil-gas entry because 1) the characteristic time for the propagation of

Allen L. Robinson; Richard G. Sextro

1995-01-01

243

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

Microsoft Academic Search

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 (~10 Pa), rapid (~20 min) fluctuations in atmospheric pressure were an important driving force for soil-gas entry because 1) the characteristic time for the propagation of

Allen L. Robinson; Richard G. Sextro

1995-01-01

244

Diode laser absorption and emission spectroscopy of a streamer discharge in an atmospheric pressure plasma jet  

Microsoft Academic Search

Research into atmospheric pressure plasma jets (APPJs) that are initiated via a self-sustaining streamer discharge has recently been driven by both their potential for applications to nonthermal material processing, and fundamental questions regarding the basic discharge mechanisms that drive this remarkably stable atmospheric pressure discharge. We have characterized a streamer-initiated atmospheric pressure plasma jet in a 5% Ar \\/ 95%

B. L. Sands; R. J. Leiweke; B. N. Ganguly

2010-01-01

245

Radio jet refraction in galactic atmospheres with static pressure gradients  

SciTech Connect

A theory of double radio sources which has 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 the method used by Begelman, Rees, and Blandford to calculate a ram-pressure model for twin radio trails (C morphology). It may also be described as a continuous-jet version of the buoyancy model proposed by Gull and Northover.

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

1981-10-01

246

Reducing pressure on the rolls and tension in the asymmetric cold-rolling of strip  

Microsoft Academic Search

Relations are presented to determine the rolling pressure and forward tension on strip during its asymmetric cold rolling.\\u000a The relations account for the reduction and strain-hardening of the strip, unit frictional forces, the difference between\\u000a the peripheral velocities of the work rolls, and the tension on the ends of the strip. Lowering the pressure of the strip\\u000a metal on the

E. A. Maksimov

2011-01-01

247

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

2013-01-02

248

Manufacture of 3D structures by cold low pressure lamination of ceramic green tapes  

Microsoft Academic Search

3D multilayer devices were generated by Laminated Object Manufacturing (LOM), a well-known rapid-prototyping technology. Divergent from this method, commercial ceramic green tapes were used which were laminated by Cold Low Pressure Lamination (CLPL). In contrast to thermo-compression, which works at pressures and elevated temperatures, CLPL allows to join particularly fine, complex structures with cavities or undercuts, because no mass flow

Karin Schindler; Andreas Roosen

2009-01-01

249

Atmospheric pressure ion focusing with a vortex stream.  

PubMed

For successful operation of ionization analysis techniques an efficient sampling and sample ion transportation into an analytical path are required. This is of particular importance for atmospheric pressure ionization sources like corona discharge, electrospray, MALDI, ionization with radioactive isotopes ((3)H, (63)Ni) that produce nonuniform spatial distribution of sample ions. The available methods of sample ion focusing with electric fields are either efficient at reduced pressure (to 1 Torr) or feature high sample losses. In this paper we suggest to use a highly whirled gas stream for atmospheric pressure ion focusing. We use a (63)Ni radioactive source to produce an ionized bipolar sample at atmospheric pressure. It is shown by experiments that compared to an aspiration method a forced highly whirled vortex stream allows one to enhance the efficiency of remote ionized sample collection at distances equal to the vortex sampler diameter by an order of magnitude. With a vortex stream, a sixfold increase in the efficiency of the radial ionized sample collection has been obtained. It may be deduced that with the vortex stream remote sampling obtains a new feature which is characterized by a considerable enhancement of the efficiency of the ionized sample collection and can be called as a "gas-dynamic" ionized sample focusing. Considered is the effect of recombination losses of the ionized sample during the remote sampling thereof with the vortex sampler. Prospects for a practical implementation of the vortex sampler for solving the problems of the customs control over the smuggling of radioactive ? and ? sources are made based on the research results. PMID:21872021

Kolomiets, Yuri N; Pervukhin, Viktor V

2011-07-12

250

Efficiency of cold passover and heated humidification under continuous positive airway pressure  

Microsoft Academic Search

Cold passover and heated humidifiers are employed for the prevention of side-effects associated with continuous positive airway pressure (CPAP) treatment. However, to date, it has not been possible to separately measure the humidity of inspired and expired air. The aim of this study was to compare the relative humidity of the inspired air and the water loss during respiration between

W. J. Randerath; J. Meier; H. Genger; U. Domanski; K. H. Ruhle

2002-01-01

251

Restoration of sensitivity in chemo-resistant glioma cells by cold atmospheric plasma.  

PubMed

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. Despite multimodal treatments including surgery, chemotherapy and radiotherapy the prognosis remains poor and relapse occurs regularly. The alkylating agent temozolomide (TMZ) has been shown to improve the overall survival in patients with malignant gliomas, especially in tumors with methylated promoter of the O6-methylguanine-DNA-methyltransferase (MGMT) gene. However, intrinsic and acquired resistance towards TMZ makes it crucial to find new therapeutic strategies aimed at improving the prognosis of patients suffering from malignant gliomas. Cold atmospheric plasma is a new auspicious candidate in cancer treatment. In the present study we demonstrate the anti-cancer properties of different dosages of cold atmospheric plasma (CAP) both in TMZ-sensitive and TMZ-resistant cells by proliferation assay, immunoblotting, cell cycle analysis, and clonogenicity assay. Importantly, CAP treatment restored the responsiveness of resistant glioma cells towards TMZ therapy. Concomitant treatment with CAP and TMZ led to inhibition of cell growth and cell cycle arrest, thus CAP might be a promising candidate for combination therapy especially for patients suffering from GBMs showing an unfavorable MGMT status and TMZ resistance. PMID:23704990

Köritzer, Julia; Boxhammer, Veronika; Schäfer, Andrea; Shimizu, Tetsuji; Klämpfl, Tobias G; Li, Yang-Fang; Welz, Christian; Schwenk-Zieger, Sabina; Morfill, Gregor E; Zimmermann, Julia L; Schlegel, Jürgen

2013-05-21

252

In-Reactor Deformation of a Pilgered Cold-Worked Zr-2.5 Wt% Nb Pressure Tube.  

National Technical Information Service (NTIS)

Zr-2.5 wt% Nb pressure tubes in CANDU reactors are cold-drawn to achieve the desired mechanical strength and tube dimensions. As part of an assessment of possible alternative fabrication processes, a pressure tube was cold-worked by pilgering and its dime...

M. D. McManus A. R. Causey

1986-01-01

253

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

Microsoft Academic Search

Summary  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

D. Peikert; J. Smolander

1991-01-01

254

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

255

[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

256

Dominant Overall Chemical Reaction in a Chlorine Trifluoride Silicon Nitrogen System at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

This study evaluates the overall chemical reaction in a chlorine trifluoride silicon nitrogen system at atmospheric pressure, based on the observation of the dominant chemical species in the gas phase using a quadrupole mass spectra analyzer coupled with a horizontal cold-wall single-wafer epitaxial reactor. Chlorine trifluoride gas etches the silicon surface, producing two major products, silicon tetrafluoride gas and chlorine gas, at room temperature and 530 K. The production of chlorosilanes was not observed in this study. The results obtained in this study indicate that the dominant overall chemical reaction in a chlorine trifluoride silicon nitrogen system is 3Si + 4ClF3 ?3SiF4 ?+ 2Cl2 ?.

Habuka, Hitoshi; Otsuka, Toru; Qu, Wei-Feng

1999-11-01

257

Microwave generation of stable atmospheric-pressure fireballs in air  

NASA Astrophysics Data System (ADS)

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.

2006-11-01

258

Study on Atmospheric Pressure Plasma Reactor for Biphenyl Decomposition  

NASA Astrophysics Data System (ADS)

Among several techniques of decomposition of dioxins offered by the present technology, possibility of application of atmospheric pressure arc was investigated. The treated substance was biphenyl due to a high risk involved while using pure dioxins during the experiment. The performance of hollow plasma reactor was investigated. In the experiment, discharge gaps' dimensions were from 5 to 20 mm, the source current ranged from 50 A to 150 A. Biphenyl was partly decomposed in a short time due to the high arc plasma temperature. Except the gaseous products, solid naphthalene and amorphous carbon were formed.

Pawlat, Joanna; Inaba, Tsuginori

259

Generation of subnanosecond electron beams in air at atmospheric pressure  

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

260

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

261

Microwave generation of stable atmospheric-pressure fireballs in air.  

PubMed

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. PMID:17279961

Stephan, Karl D

2006-11-14

262

Electrode erosion in arc discharges at atmospheric pressure  

SciTech Connect

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

Continuous nanoparticle generation and assembly by atmospheric pressure arc discharge  

NASA Astrophysics Data System (ADS)

This letter describes a nanoparticle generation and deposition system which combines aspects of high temperature plasmas with room temperature aerosols. The process works at atmospheric pressure and produces nanoparticles of Au or ZnO through cathode erosion inside a dc arc discharge plasma. The particles are positively charged by the arc and form a room temperature aerosol. From the aerosol, nanoparticles assemble on conductive sample surfaces through openings in patterned resist with resolution enhanced by electrodynamic nanolenses. We report that continued operation of the system results in funneled deposition of nanoparticles into well positioned three dimensional nanostructures.

Cole, Jesse J.; Lin, En-Chiang; Barry, Chad R.; Jacobs, Heiko O.

2009-09-01

264

Arc-cold cathode interactions: parametric dependence on local pressure  

NASA Astrophysics Data System (ADS)

A numerical model describing the attachment of an electric arc on a vaporizing non-refractory cathode is developed and applied to a Cu cathode. The model describes the arc - cathode interaction zone by a combination of a quasi-stationary vacuum arc cathode spot model with a collisionless cathode sheath model for the current transfer in the cathode region. The conditions of pressure and electron temperature within the cathode spot plasma necessary to account for current densities ranging from 0963-0252/6/4/008/img1 A 0963-0252/6/4/008/img2 (upper limit for non-vaporizing cathode models) to 0963-0252/6/4/008/img3 A 0963-0252/6/4/008/img2 are presented. Results show that current densities higher than 0963-0252/6/4/008/img5 A 0963-0252/6/4/008/img2 can only be accounted for with metallic plasma pressures exceeding 35 atm and electron temperatures ranging from 1 to 2 eV within the cathode spots. The current transfer to the cathode is mainly assumed by the ions at low current densities (0963-0252/6/4/008/img7 A 0963-0252/6/4/008/img2) and by the thermo-field electrons for higher current densities. The heat flux to the cathode surface under the spots is mainly due to the flux of returning ions and ranges from 0963-0252/6/4/008/img9 to 0963-0252/6/4/008/img10 W 0963-0252/6/4/008/img2 for current densities ranging from 0963-0252/6/4/008/img12 to 0963-0252/6/4/008/img5 A 0963-0252/6/4/008/img2. At low current densities (0963-0252/6/4/008/img15), the main heat loss is by conduction through the cathode while at high current densities, the Nottingham cooling associated with the thermo-field emission of electrons dominates. The model allowed us to define the upper and lower limits for the vacuum erosion rate by vaporization of the cathode. It is shown that the experimentally obtained vacuum erosion rate value for Cu falls between both limits for an electron temperature within the cathode spot of 1 to 2 eV.

Coulombe, Sylvain; Meunier, Jean-Luc

1997-11-01

265

Next generation of the atmospheric pressure loading service  

NASA Astrophysics Data System (ADS)

A major revision of the service of the atmospheric pressure loading launched in 2002 is scheduled to be completed in 2013. Revised service accessible at http://astrogeo.org/loading will have improved accuracy, reduced latency, and better user interface. Improvement in accuracy will be achieved owing to using numerical models with much higher resolution (several tens of kilometers versus several hundreds of kilometers) owing to more precise surface pressure reduction, and owing to taking into account the dynamic response of the ocean. Using operational numerical weather models matched to reanalysis model allows us to compute loading with latencies measured by hours. Using advanced algorithms for loading computation running at high performance computer allows to offer a service of computing loading on the fly.

Petrov, Leonid; Boy, Jean-Paul

2013-04-01

266

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

267

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

268

Growth of wheat under one tenth of the atmospheric pressure.  

PubMed

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. PMID:11542536

Massimino, D; Andre, M

1999-01-01

269

Characterizing Electrospray Ionization Using Atmospheric Pressure Ion Mobility Spectrometry  

PubMed Central

Reduced flow-rate electrospray ionization has been proven to provide improved sensitivity, less background noise, and improved limits of detections for ESI-MS analysis. Miniaturizing the ESI source from conventional electrospray to micro-electrospray and further down to nano-electrospray has resulted in higher and higher sensitivity. However, when effects of flow rate were investigated for atmospheric pressure ESI-IMS using a nanospray emitter, a striking opposite result was observed. The general tendency we observed in ESI-IMS was that higher flow rate offered higher ion signal intensity throughout a variety of conditions investigated. Thus further efforts were undertaken to rationalize these contradictory results. It is well accepted that decreased flow rate increases both ionization efficiency and transmission efficiency thus improves ion signal in ESI-MS. However, our study revealed that decreased flow rate results in decreased ion signal because ion transfer is constant no matter how flow rate changes in ESI-IMS. Since ion transfer is constant in atmospheric pressure ESI-IMS, ionization efficiency can be studied independently, which otherwise is not possible in ESI-MS where both ionization efficiency and transmission efficiency vary as conditions alter. In this report, we present a systematic study on signal intensity and ionization efficiency at various experimental conditions using ESI-IMS and demonstrated the ionization efficiency as a function of flow rate, analyte concentration, and solvent composition.

Tang, Xiaoting; Bruce, James E.; Hill, Herbert H.

2013-01-01

270

[Vibrational temperature of plasma plume in atmospheric pressure air].  

PubMed

A tri-electrode discharge device was designed in a dielectric barrier discharge configurations to generate a fairly large volume plasma plume in atmospheric pressure air. The discharge characteristics of the plasma plume were investigated by an optical method. The discharge emission from the plasma plume was collected by a photomultiplier tube. It was found that the number of discharge pulse per cycle of the applied voltage increased with increasing the peak value of the applied voltage. The emission spectra of the plasma plume were collected by a spectrometer. The vibrational temperature was calculated by fitting the experimental data to the theoretical one. Results showed that the vibrational temperature of the plasma plume decreases with increasing the U(p). Spatially resolved measurement of the vibrational temperature was also conducted on the plasma plume with the same method. Results showed that the vibrational temperature increases firstly and then decreases with increasing distance from the nozzle. The vibrational temperature reachs its maximum when the distance is 5.4 mm from the nozzle. These experimental phenomena were analyzed qualitatively based on the discharge theory. These results have important significance for the industrial applications of the plasma plume in atmospheric pressure air. PMID:24059168

Li, Xue-Chen; Chang, Yuan-Yuan; Jia, Peng-Ying; Zhao, Huan-Huan; Bao, Wen-Ting

2013-07-01

271

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

272

Atmospheric Pressure RF Plasma Electrical and Optical Characteristics  

NASA Astrophysics Data System (ADS)

An atmospheric pressure 13.56 MHz RF source is used for plasma polymerization, nanocomposite deposition and for sterilization purposes. The air discharge electrical and optical characteristics are measured using monochromator and electrical probes. The addition of helium flow to the RF discharge system allows production of stable glow plasma discharge. The electron temperature and plasma densities are estimated using the emission lines of HeI and double probes. Emission of the He+air atmospheric pressure plasma is observed from the OH radical, several lines of the N2, N2^+ and atomic O, H and He lines. He flow rate and applied rf voltage affect on these emission spectra are investigated and the spectral lines are used for calculation of plasma parameters. Plasma electron temperature is calculated using HeI lines and compared with double probe data. The OI 777 and H? 656 lines are also investigated by varying the applied voltage and He flow rate. The calculated electron temperature was approximately 0.2 eV and dependent on the He flow rate and applied power.

Gulec, Ali; Oksuz, Lutfi; Hershkowitz, Noah

2009-10-01

273

Benzene Dissociation in DC Atmospheric Pressure Air Glow Discharges  

NASA Astrophysics Data System (ADS)

By using a micro-hollow cathode discharge (MHCD) as an electron source to lower or eliminate the cathode fall voltage, a glow discharge could be operated in a dc atmospheric pressure air [1]. The effect of this glow discharge plasma on VOC (Volatile Organic Compound) remediation, particularly, benzene remediation, has been studied. A higher than 90 % destruction rate has been obtained by flowing a 300 ppm benzene/ dry air mixture through the plasma filament. The plasma is confined by a dielectric to a cross-section of 1 mm by 1.5 mm and extends over a depth of 0.8 mm. With a flow rate of 100 sccm, the residence time of the gas in the plasma column is 0.7 ms. A destruction efficiency of more than 0.5 L/kJ has been measured. The energy efficiency is 0.9 g/kWh which is comparable to that achieved by low pressure glow discharges in benzene/ noble gas mixtures [2]. References: [1] R. H. Stark and K. H. Schoenbach, "Direct Current Glow Discharges in Atmospheric Air," Appl. Phys. Lett. 89, 3568 (2001). [2] D. L. McCorkle, W. Ding, C. Ma and L. A. Pinnaduwage, "Dissociation of Benzene and Methylene Chloride Based on Enhanced Dissociative Electron Attachment to Highly Excited Molecules," J. Phys. D: Appl. Phys. 32, 46 (1999). Acknowledgments: This work is supported by the Air Force Office of Scientific Research.

Jiang, Chunqi; Stark, Robert H.; Schoenbach, Karl H.

2001-10-01

274

The responses of skin blood flow, mean arterial pressure and R-R interval induced by cold stimulation with cold wind and ice water.  

PubMed

This study was designed to evaluate the peripheral circulation response to cold wind stimulation. Skin blood flow (SBF), ECG R-R intervals (RRs) and mean arterial pressure (MAP) were measured in ten healthy men under strictly controlled conditions. Cold wind flow and ice water bath were prepared as cold stimulations. The subjects were exposed to each cold stimulation and the values of the responses were simultaneously recorded. The cold wind stimulation reduced SBF (maximally 40.4 +/- 3.2%) and increased MAP (maximally 106.9 +/- 1.3%), but did not affect RRs. On the other hand, all parameters were affected by the ice water stimulation, which reduced SBF to 16.4 +/- 1.2% and RRs to 85.1 +/- 3.0%, and increased MAP to 130.6 +/- 2.4% compared with the control state. All subjects suffered from intense pain during the ice water but not the cold wind stimulation, and two of them were eliminated from this study because of vagotonia. After phentolamine iontophoresis was used to block the receptor of peripheral alpha-adrenergic nerve terminals, the cold wind stimulation did not affect SBF. These results suggest that cold wind stimulation is a useful test for evaluating peripheral alpha-adrenergic nerve function in relation to cold sensation, without increase of RRs and noxious pain. PMID:8946327

Shibahara, N; Matsuda, H; Umeno, K; Shimada, Y; Itoh, T; Terasawa, K

1996-11-01

275

Contact-free inactivation of Trichophyton rubrum and Microsporum canis by cold atmospheric plasma treatment.  

PubMed

Aim: Cold atmospheric plasma (CAP) has already proven efficient at disinfection of microorganisms including biofilms. The objective of the present study is to assess the efficacy of CAP against the dermatophytes Trichophyton rubrum and Microsporum canis in vitro. Materials & methods:T. rubrum and M. canis were exposed to CAP for different treatment times and time intervals in vitro. Treatment with ciclopirox olamine or UVC radiation (0.120 J/cm(2)) served as controls. CAP was generated by the surface microdischarge technology. Fungal colony growth was measured upon CAP treatment. Results: Repeated daily CAP treatments of 10 min demonstrated an inhibition of growth during the treatment period of 9 days. Single CAP treatment sessions for 5, 8 and 10 min, as well as treatments for 5 or 8 min daily, resulted in less fungal growth inhibition. UVC radiation treatment failed, but not ciclopirox olamine. Conclusion: CAP shows promising potential for future application in the treatment of dermatophyte infections. PMID:24020738

Heinlin, Julia; Maisch, Tim; Zimmermann, Julia L; Shimizu, Tetsuji; Holzmann, Thomas; Simon, Michaela; Heider, Judith; Landthaler, Michael; Morfill, Gregor; Karrer, Sigrid

2013-09-01

276

Downstream modulation of North Pacific atmospheric river activity by East Asian cold surges  

NASA Astrophysics Data System (ADS)

An East Asian cold surge (EACS) is characterized by rapid advancement of a polar airmass toward the east coast of the Eurasian continent in boreal winter. Over the east coast of Asia, extratropical cyclogenesis and the amplitudes of atmospheric disturbances ranging from synoptic to subseasonal timescales are immediately enhanced as the cold air approaches. This study investigates for the first time the impact of these EACS-excited disturbances on the activity of atmospheric rivers (ARs) over the North Pacific. Applying a new AR detection algorithm to the NASA MERRA dataset, we show that the daily occurrence probability of ARs over the eastern North Pacific near the west coast of U.S. is effectively modulated by EACS. In particular, this downstream dynamical modulation goes through two distinct stages: during the period Day 0-3, where Day 0 corresponds to the time of the peak intensity of an EACS event, high-frequency (HF, <6-day) baroclinic disturbances developed over the western North Pacific and Gulf of Alaska lead to significant poleward moisture transport over these two regions, and during the period Day 4-6, intermediate-low frequency (IF-LF, >12-day) barotropic disturbances developed from the merging of high-frequency troughs increase the daily occurrence probability of ARs near the west coast of the U.S. by 50%, relative to the climatological value. The results reported here demonstrate the critical role of IF and LF disturbances in establishing the link between the predictability of EACS and that of the AR-related extreme precipitation events in the western U.S. in boreal winter.

Jiang, Tianyu; Deng, Yi

2011-10-01

277

Operation of a pneumatic piston-type drive with discharge into a medium with pressure greater than atmospheric pressure  

Microsoft Academic Search

UDC 621.231 Calculations of the energy parameters of a pneumatic piston-type drive make use of the absolute pressure of compressed air, setting it equal to unity in the atmosphere. Fluctuations that occur in the atmospheric air pressure are comparatively slight and, for this reason, results of calculations are in good agreement with the field values of the parameters. When working

Kh. B. Tkach

1996-01-01

278

Numerical Study of In-flight Particle Parameters in Low-Pressure Cold Spray Process  

NASA Astrophysics Data System (ADS)

A 2-D model of the low-pressure cold spray with a radial powder feeding was established using CFD software in this study. The flow field was simulated for both propellant gases of nitrogen and helium. To predict the in-flight particle velocity and temperature, discrete phase model was introduced to simulate the interaction of particle and the supersonic gas jet. The experimental velocity of copper powder with different sizes was used to validate the calculated one for low-pressure cold spray process. The results show that the computational model can provide a satisfactory prediction of the supersonic gas flow, which is consistent with the experimental Schlieren photos. It was found that similar velocity was obtained with the drag coefficient formula of Henderson and with that of Morsi and Alexander. As the shape factor was estimated, the reasonable prediction of velocity for non-spherical particle can be obtained, to compare with the experimental results.

Ning, Xian-Jin; Wang, Quan-Sheng; Ma, Zhuang; Kim, Hyung-Jun

2010-12-01

279

Heritability of Blood Pressure Responses to Cold Pressor Test in a Chinese Population  

Microsoft Academic Search

BackgroundGenetic determinants of blood pressure (BP) responses to the cold pressor test (CPT), a phenotype associated with risk of hypertension and cardiovascular disease has not been well studied.MethodsWe examined the heritability of BP response to CPT in 1,994 subjects from 627 families in rural north China. BP was measured before and at 0, 1, 2, and 4 min after the

Hao Mei; Dongfeng Gu; Treva K. Rice; James E. Hixson; Jing Chen; Cashell E. Jaquish; Qi Zhao; Chung-Shiuan Chen; Ji-Chun Chen; C. Charles Gu; Tanika N. Kelly; Jiang He

2009-01-01

280

Effects of residual stress in creep crack growth analysis of cold bent tubes under internal pressure  

Microsoft Academic Search

In this paper, the effects of residual stresses are considered in crack growth of cold bent and longitudinally cracked carbon–manganese tubes and pipes tested under pressure at 360°C, using the fracture mechanics parameters reference stress, ?ref, K and C?. Residual stress measurements using the X-Ray diffraction technique and a successive layer removal method have been performed through the thickness of

O Kwon; B Pathiraj; K. M Nikbin

2001-01-01

281

Area postrema is essential for the maintenance of normal blood pressure under cold stress in rats  

Microsoft Academic Search

No final conclusion has yet been achieved on whether the area postrema (AP) is involved in the regulation of cardiovascular\\u000a activity in the rats. The aim of the present study was to investigate the role of the AP in the regulation of basal blood\\u000a pressure under normal as well as abnormal (cold stress) conditions in Sprague-Dawley rats. The lesion of

Zhong Ming Qian; Hon Wai Koon

1998-01-01

282

Investigation of sterilization mechanism by atmospheric pressure plasma jet system (APPJS)  

Microsoft Academic Search

In this study, the atmospheric pressure plasma jet system (APPJS), which dispersed a plasma by injected gas pressure, was used to solve drawbacks of conventional sterilization methods of an atmospheric pressure plasma. To confirm that APPJS is superior to conventional plasma systems in the sterilization process, the characteristics of APPJS is compared with those of conventional plasma systems. In addition

Y. K. Lee; J. H. Choi; E. S. Lee; S. J. Lee; K. M. Song; H. K. Baik

2003-01-01

283

Effect of microbial loading on the efficiency of cold atmospheric gas plasma inactivation of Salmonella enterica serovar Typhimurium  

Microsoft Academic Search

In recent years the application of cold atmospheric gas plasma (CAP) aimed at the removal of microbial contamination from fresh and minimally processed food has received increased attention. For CAP to be successfully adopted by the food production industry, factors which affect its potential for microbial inactivation must be evaluated. In this study, we examined the effects of initial microbial

A. Fernández; N. Shearer; D. R. Wilson; A. Thompson

284

Effects of Gas Pressure of Cold Spray on the Formation of Al-Based Intermetallic Compound  

NASA Astrophysics Data System (ADS)

In this paper, postannealing of cold-sprayed (CDGS) coatings for intermetallic compounds (IMC) in the matrix at low temperature and dependences of types and dispersion characteristics of intermetallic compounds on spraying pressure condition were investigated. The pressure prior to entering the gas heater was fixed at 0.7, 1.5, and 2.5 MPa. The relatively soft Al has been coated at low gas pressure condition (0.7 MPa) with severe plastic deformation owing to large peening effect. On the contrary, the Al particles coated at the higher pressure (1.5, 2.5 MPa) were not severely deformed. It was concluded that the pressure-controlled peening effects could alter the main route of Al consumption during annealing: eutectic or compounding of intermetallics. The thin and continuous IMC layer was formed at the interface with low pressure condition (0.7 MPa). On the other hand, the thick and discontinuous IMC layer was observed at the higher pressure condition (1.5, 2.5 MPa). Also, many eutectic pores were found in the Al-Ni composite coatings with lower gas pressure condition (0.7 MPa), but far less were found with high pressure environment.

Lee, H.; Shin, H.; Ko, K.

2010-01-01

285

Atmospheric loss and supply by an impact-induced vapor cloud: Its dependence on atmospheric pressure on a planet  

NASA Astrophysics Data System (ADS)

Hypervelocity impact would vaporize the impactor and part of planetary surface and create a rock vapor cloud. Results from previous studies suggest that the energetic impact would have a role to blow off and cause a large-scale loss of the planetary atmosphere through expansion of the vapor cloud. Impact also has been considered as a material source. Numerous, repeated impact events during the heavy bombardment period could greatly affect the amount of volatiles and the atmospheric pressure on the planetary surface in either way. To discuss the evolution of the atmospheric pressure by impacts, we carried out hydro-calculations with a two-dimensional hydrodynamic code and investigated the dependence of the loss and supply of the atmosphere on the atmospheric pressure. We integrated both effects by impacts over impactor size distribution and assessed the evolution of the atmospheric pressure on early Mars. Using this approach, we found that the numerous impacts likely increase the atmosphere monotonically or control the atmospheric pressure to some value, rather than causing the monotonic decrease as the previous study suggested.

Hamano, K.; Abe, Y.

2010-07-01

286

A dielectric barrier discharge in neon at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A dielectric barrier discharge in neon at atmospheric pressure is investigated with electrical measurement and fast photography. It is found that a stable diffuse discharge can be easily generated in a gap with a gap space of 0.5-6 mm and is identified with a glow discharge. The first breakdown voltage of the gap is considerably higher than that of the same gap working in a stable diffuse discharge mode, which indicates that Penning ionization of neon metastables from the previous discharge with inevitable gas impurities plays an important role in the decrease in the breakdown voltage. Discharge patterns are observed in a gap shorter than 1 mm. From the experiments with a wedge-like gap, it is found that the discharge patterns are formed in the area with a higher applied electric field, which suggests that a higher applied electric field may cause a transition from a diffuse glow to discharge patterns.

Ran, Junxia; Luo, Haiyun; Wang, Xinxin

2011-08-01

287

Synthesis of silicon nanocones using rf microplasma at atmospheric pressure  

SciTech Connect

We report the synthesis of silicon nanocones using the rf microplasma discharge at atmospheric pressure. The products formed underneath the tube electrode on Fe-coated crystalline silicon were constituted mainly of silicon and silicon oxide despite the use of a methane-argon mixture. Carbon nanotubes and silicon nanowires were also formed around the silicon nanocones. The number density and average size of silicon nanocones increased with the plasma exposure time accompanied by the enlargement of their surface distribution. The growth mechanism of silicon nanocones is discussed in terms of the catalytic growth via diffusion of silicon with nanocrystalline Si particle through FeSi{sub x} nanoclusters, and enhanced Si oxidation by the plasma heating.

Shirai, H.; Kobayashi, T.; Hasegawa, Y. [Department of Functional Materials Science, Faculty of Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan); Institute of Physics and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Graduate School of Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura, Saitama338-8570 (Japan)

2005-10-03

288

Atmospheric pressure argon plasma jet using a cylindrical piezoelectric transformer  

NASA Astrophysics Data System (ADS)

A low-voltage atmospheric pressure nonthermal argon plasma jet using a circular piezoelectric transducer is proposed. An Ar plasma flame is generated at an input voltage of 87 V. The consumed power is 2 W. The electrical and optical properties of the jet are analyzed. In particular, the transient Ar discharge ignition and evolution including the so-called plasma bullet phenomenon is examined temporally resolved with the aid of a fast camera. It is found that four discharge phases can be identified, designated as ignition, extension, self-propagation, and attenuation. The plasma bullet is launched while the electric field in the discharge space is decreasing. The average bullet velocity is 23 km/s.

Kim, Hyun; Brockhaus, Albrecht; Engemann, Jürgen

2009-11-01

289

Epoxy Resin Surface Functionalization Using Atmospheric Pressure Plasma Jet Treatment  

NASA Astrophysics Data System (ADS)

Atmospheric pressure plasma jet (APPJ) of N2 has been applied to promote adhesion between the epoxy resin post and composite core material due to the chemical active functional groups created. The APPJ was proved to be able to improve adhesive ability of the epoxy resin through the polar groups such as carbonyl group on its surface revealed by decreasing contact angle. The jet was generated from N2/Ar and N2/He gas mixture with ratio as low as 0.40--0.44 vol %, respectively. The optical emission spectrometry showed that the active species which could react with the substrate surface are nitrogen molecules and nitrogen molecules ion. The radial distribution functions (RDFs) calculations indicated that the most probable position of nitrogen active species reacting on the epoxy surface is at hydroxyl group with hydrogen bonding distance less than 35 nm.

Sangprasert, Waleepan; Nimmanpipug, Piyarat; Yavirach, Piriya; Lee, Vannajan Sanghiran; Boonyawan, Dheerawan

2012-01-01

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

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

292

Supershort electron beam from air filled diode at atmospheric pressure  

NASA Astrophysics Data System (ADS)

The properties of an electron beam (e-beam) formed in air under atmospheric pressure are reported. The nanosecond generators RADAN-303 (two devices) and RADAN-220, producing nanosecond voltage pulses with amplitude of up to 400 kV and subnanosecond rise time were used in the experiments. It was shown for the first time that the duration of e-beam current of gas diode behind the foil does not exceed 0.1 ns. The maximum amplitude of current of a supershort avalanche electron beam (SAEB) behind the foil was [similar]400 A. The data on the influence of various parameters on e-beam current amplitude measured behind the foil were obtained. An electron beam with energy less than 60 keV and powerful X-ray radiation were formed in discharge gap simultaneously with SAEB.

Tarasenko, V. F.; Shunailov, S. A.; Shpak, V. G.; Kostyrya, I. D.

2005-10-01

293

FT-IR measurements of cold C3H8 cross sections at 7–15 ?m for Titan atmosphere  

NASA Astrophysics Data System (ADS)

We present absorption cross sections of propane (C3H8) at temperatures from 145 K to 297 K in the 690–1550 cm?1 region. Pure and N2-broadened spectra were measured at pressures from 3 Torr to 742 Torr using a Bruker IFS125 FT-IR spectrometer at JPL. The gas absorption cell, developed at Connecticut College, was cooled by a closed-cycle helium refrigerator. The cross sections were measured and compiled for individual spectra recorded at various experimental conditions covering the planetary atmosphere and Titan. In addition to the cross sections, a propane pseudoline list with a frequency grid of 0.005 cm?1, was fitted to the 34 laboratory spectra. Line intensities and lower state energies were retrieved for each line, assuming a constant width. Validation tests showed that the pseudoline list reproduces discrete absorption features and continuum, the latter contributed by numerous weak and hot band features, in most of the observed spectra within 3%. Based on the pseudoline list, the total intensity in the 690–1550 cm?1 region was determined to be 52.93 (±3%) × 10?19 cm?1/(molecule cm?2) at 296 K; this value is within 3% of the average from four earlier studies. Finally, the merit of the pseudoline approach is addressed for heavy polyatomic molecules in support of spectroscopic observation of atmospheres of Titan and other planets. The cold cross sections will be submitted to the HITRAN database (hitran.harvard.edu), and the list of C3H8 pseudolines will be available from a MK-IV website of JPL (http://mark4sun.jpl.nasa.gov/data/spec/Pseudo).

Sung, Keeyoon; Toon, Geoffrey C.; Mantz, Arlan W.; Smith, Mary Ann H.

2013-11-01

294

Efficiency of cold passover and heated humidification under continuous positive airway pressure.  

PubMed

Cold passover and heated humidifiers are employed for the prevention of side-effects associated with continuous positive airway pressure (CPAP) treatment. However, to date, it has not been possible to separately measure the humidity of inspired and expired air. The aim of this study was to compare the relative humidity of the inspired air and the water loss during respiration between cold passover and heated humidifiers under CPAP. Humidity and temperature were determined separately for the respiratory phases, without humidification, with cold passover and heated humidifiers in 10 healthy subjects. Humidity was measured with a capacitive hygrometer, temperature with a "Type K" thermosensor, and impedance of the total respiratory system with impulse oscillometry. The relative humidity (rH) of the inspired air (mean+/-SD) increased significantly from 24.0+/-9.1%, rH (34.8+/-1.0 degrees C, no humidifier) to 34.5+/-10.1%, rH (34.6+/-1.0 degrees C) under cold humidification, and to 53.9+/-13.2% rH (35.0+/-1.1 degrees C) under heated humidification. With heated humidification, water loss was reduced by 38% compared to cold humidification. The impedance increased from 5.7+/-1.8 cmH2O x L x s(-1) (no humidifier) to 6.7+/-1.8 cmH2O x L x s(-1) (heated humidifier). The authors conclude that the use of a heated humidifier during continuous positive airway pressure appreciably increases the relative humidity of the inspired air and reduces the water loss during respiration. PMID:12166568

Randerath, W J; Meier, J; Genger, H; Domanski, U; Rühle, K H

2002-07-01

295

Radial pressure pulse and heart rate variability in heat- and cold-stressed humans.  

PubMed

This study aims to explore the effects of heat and cold stress on the radial pressure pulse (RPP) and heart rate variability (HRV). The subjects immersed their left hand into 45°C and 7°C water for 2 minutes. Sixty healthy subjects (age 25 ± 4?yr; 29 men and 31 women) were enrolled in this study. All subjects underwent the supine temperature measurements of the bilateral forearms, brachial arterial blood pressure, HRV and RPP with a pulse analyzer in normothermic conditions, and thermal stresses. The power spectral low-frequency (LF) and high-frequency (HF) components of HRV decreased in the heat test and increased in the cold test. The heat stress significantly reduced radial augmentation index (AIr) (P < .05), but the cold stress significantly increased AIr (P < .01). The spectral energy of RPP did not show any statistical difference in 0 ~ 10?Hz region under both conditions, but in the region of 10 ~ 50?Hz, there was a significant increase (P < .01) in the heat test and a significant decrease in the cold test (P < .01). The changes in AIr induced by heat and cold stress were significantly negatively correlated with the spectral energy in the region of 10 ~ 50?Hz (SE(10-50?Hz)) but not in the region of 0 ~ 10?Hz (SE(0-10?Hz)). The results demonstrated that the SE(10-50?Hz), which only possessed a small percentage in total pulse energy, presented more physiological characteristics than the SE(0-10?Hz) under the thermal stresses. PMID:21113292

Huang, Chin-Ming; Chang, Hsien-Cheh; Kao, Shung-Te; Li, Tsai-Chung; Wei, Ching-Chuan; Chen, Chiachung; Liao, Yin-Tzu; Chen, Fun-Jou

2010-11-14

296

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

297

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

298

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

Microsoft Academic Search

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 (â10 Pa), rapid (â 20 min) fluctuations in atmospheric pressure were an important driving force for soil-gas entry because (1) the characteristic time for the propagation

Allen L. Robinson; Richard G. Sextro

1995-01-01

299

Effect of Penicillin on Staphylococcus Aureus Cultivated at High Atmospheric Pressure.  

National Technical Information Service (NTIS)

Staphylococcus aureus showed decreased penicillin susceptibility at high atmospheric pressure (0.3% oxygen in helium, 1,000 psi). High pressure may have protected bacteria by osmotic stabilization. (Author)

N. A. Schlamm A. L. Coykendall C. E. Meyers

1968-01-01

300

Growth of Escherichia Coli in High Pressure Helium-Oxygen Gas Atmospheres.  

National Technical Information Service (NTIS)

Growth of Escherichia coli strain W was accelerated by pressurization to 68 atm (1000 psig) with helium-oxygen gas atmospheres. The acceleration appeared to be related to sequestration of iron and more efficient iron utilization by pressurized cells. (Aut...

N. A. Schlamn J. E. Perry

1970-01-01

301

Atmosphere  

NSDL National Science Digital Library

What is this atmosphere that surrounds the Earth? This instructional tutorial, part of an interactive laboratory series for grades 8-12, introduces students to the structure, effects, and components of the atmosphere. Here students investigate the composition of the atmosphere; effects of temperature, pressure, and ozone; the greenhouse effect; and how Earth compares with other planets. Interactive activities present students with opportunities to explore ideas and answer questions about the atmosphere, including its structure, the making of ozone, rocket launching, and measuring the atmosphere. Pop-up boxes provide additional information on topics such as dust, rain, and atmospheric composition. Students complete a final written review of six questions about the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

302

Influence of environmental moisture on atmospheric pressure plasma jet treatment of ultrahigh-modulus polyethylene fibers  

Microsoft Academic Search

One of the main differences between low-pressure and atmospheric-pressure plasma treatments is that there is little moisture involved in the low-pressure plasma treatment, although moisture could exist at the wall of the vacuum chamber or react with the substrate after plasma treatment, while in the atmospheric-pressure plasma treatment moisture exists not only in the environment but also in any hygroscopic

Y. Liu; H. Xu; L. Ge; C. Wang; L. Han; H. Yu; Y. Qiu

2007-01-01

303

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

304

Investigation of the mutagenic potential of cold atmospheric plasma at bactericidal dosages.  

PubMed

In the past few years, cold atmospheric plasma (CAP) has evolved into a new tool in the fight against nosocomial infections and antibiotic-resistant microorganisms. The products generated by the plasma-electrons, ions, reactive species and UV light-represent a 'lethal cocktail' for different kinds of pathogen, which opens up possible applications in hygiene and medicine. Nevertheless, to ensure the safe usage of CAP on skin (e.g., to treat wounds or skin diseases) several pre-clinical in vitro studies have to be performed before implementing clinical trials on humans. In the study presented here, inactivation experiments with Escherichia coli were carried out to identify the necessary plasma dosage for a 5 log reduction: with a small hand-held battery-operated CAP device, these disinfection properties were achieved after application during 30s. This and higher plasma dosages were then used to analyze the mutagenicity induced in V79 Chinese hamster cells-to furthermore define a 'safe application window'-with the HPRT (hypoxanthine-guanine phosphoribosyl transferase) mutation assay. The results show that a CAP treatment of up to 240 s and repeated treatments of 30s every 12h did not induce mutagenicity at the Hprt locus beyond naturally occurring spontaneous mutations. PMID:23416235

Boxhammer, V; Li, Y F; Köritzer, J; Shimizu, T; Maisch, T; Thomas, H M; Schlegel, J; Morfill, G E; Zimmermann, J L

2013-02-14

305

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

306

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

307

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

308

Airborne lidar measurements of atmospheric pressure made using the oxygen A-band  

NASA Astrophysics Data System (ADS)

We report on the atmospheric pressure measurements using a fiber-based laser system using the oxygen A-band at 765 nm. Remote measurements of atmospheric temperature and pressure are required for a number of scientific applications including greenhouse gas monitoring, weather prediction, and climate modeling.

Riris, Haris; Rodriguez, Michael D.; Allan, Graham R.; Hasselbrack, William E.; Stephen, Mark A.; Abshire, James B.

2011-09-01

309

Biomedical Applications of Low Temperature Atmospheric Pressure Plasmas to Cancerous Cell Treatment and Tooth Bleaching  

Microsoft Academic Search

Low temperature atmospheric pressure plasmas have attracted great interests and they have been widely applied to biomedical applications to interact with living tissues, cells, and bacteria due to their non-thermal property. This paper reviews the biomedical applications of low temperature atmospheric pressure plasmas to cancerous cell treatment and tooth bleaching. Gold nanoparticles conjugated with cancer-specific antibodies have been introduced to

Jae Koo Lee; Myoung Soo Kim; June Ho Byun; Kyong Tai Kim; Gyoo Cheon Kim; Gan Young Park

2011-01-01

310

Plasma Decomposition of Clathrate Hydrates by 2.45 GHz Mircowave Irradiation at Atmospheric Pressure  

Microsoft Academic Search

The purpose of this research is to develop a process to use the plasma decomposition of clathrate hydrates to produce fuel gas. An ordinary microwave (MW) oven is used as the source of 2.45 GHz MW radiation under atmospheric-pressure. The plasma decomposition of the hydrates could pave the way for a new utilization of atmospheric pressure plasma. Cyclopentane (CP) hydrate

Shinfuku Nomura; Andi Erwin Eka Putra; Shinobu Mukasa; Hiroshi Yamashita; Hiromichi Toyota

2011-01-01

311

Influence of barrier material and surface roughness on atmospheric pressure uniform dielectric barrier discharge in air  

Microsoft Academic Search

Summary form only given. An atmospheric pressure uniform discharge has a great potential for improving surface treatment, efficiency of ozone generation, de-NOx and so on. So far, we have studied a stable generation of atmospheric pressure uniform discharge using dielectric barrier discharge device, and we already reported that by elevating barrier temperature or by using acrylic barrier material, the discharge

N. Osawa; Y. Mochizuki; Y. Yoshioka

2009-01-01

312

Flammability limits and laminar flame speed of hydrogeneair mixtures at sub-atmospheric pressures  

Microsoft Academic Search

Hydrogen behavior at elevated pressures and temperatures was intensively studied by numerous investigators. Nevertheless, there is a lack of experimental data on hydrogen ignition and combustion at reduced sub-atmospheric pressures. Such conditions are related to the facilities operating under vacuum or sub-atmospheric conditions, for instance like ITER vacuum vessel. Main goal of current work was an experimental evalu- ation of

M. Kuznetsov; S. Kobelt; J. Grune; T. Jordan

2012-01-01

313

Lissajous Figure Characteristics of High Frequency Homogeneous Dielectric Barrier Discharge in Helium at Atmospheric Pressure  

Microsoft Academic Search

There are three models of Dielectric barrier discharge under atmospheric pressure, and a simple, effective diagnostic method to distinguish the discharge mode is urgently brought forward. Based on dielectric barrier electrodes, glow, pseudoglow homogeneous discharges under an 11.8 kHz voltage in helium at atmospheric pressure and filamentary discharges in air were investigated by measurements of discharge current and Lissajous figure.

X. L. Wang; Y. P. Hao; L. Yang

2008-01-01

314

Carbon dioxide reforming of methane to synthesis gas by an atmospheric pressure plasma jet  

Microsoft Academic Search

An experimental investigation on CO2 reforming of CH4 to synthesis gas was performed using a novel atmospheric pressure plasma jet, which is initiated by an alternating current of 50 Hz and a high ratio transformer. The plasma jet proved to be a stable and uniform atmospheric pressure discharge that held the advantages of both thermal and nonthermal plasma. The effects

Xiang LI; Mei-gui BAI; Xu-mei TAO; Shu-yong SHANG; Yong-xiang YIN; Xiao-yan DAI

2010-01-01

315

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

316

Forbush-effects and atmospheric pressure dynamics at high-altitude Tien Shan station  

NASA Astrophysics Data System (ADS)

We present atmospheric pressure dynamics studies at the high-altitude Tien Shan station (3340 m above sea level) during 23rd cycle of solar activity after Forbush-effects. It is established that 80 % of Forbush effects with delay 1 ÷ 3 days are accompanied with steady depression of atmospheric pressure irrespective of geomagnetic field conditions. We found that atmospheric pressure dynamics at mountains and ground levels during investigated periods is different. Experimental results are compared with possible mechanisms of influence of sporadic effects of solar activity on circulation of the lower atmosphere.

Antonova, V.; Kryukov, S.

2013-02-01

317

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

318

Ion chemistry in gaseous discharges at atmospheric pressure  

NASA Astrophysics Data System (ADS)

The role of ions in plasma chemistry is briefly reviewed on the basis of recent literature reports. In addition, different chemical processes induced by gaseous discharges at atmospheric pressure are discussed here, with particular emphasis on the elucidation of some aspects of the ion chemistry occurring in benzene/air dielectric barrier and corona discharges. Through a multi-technique approach relying on gas chromatographic, mass spectrometric, spectroscopic and computational analyses, we have been able to reveal subtle mechanistic aspects involved in the ionic processes leading to the synthesis of covalent adducts. In particular, we report here the experimental conditions and the thermochemical reasons whereby we can access the synthesis (i) of benzenediazonium ion {\\rmC}_6H_{5}N_2^+ from the reaction of phenylium ion C_6H_5^+ with N2, (ii) of protonated biphenyl ions C_12H_{11}^+ from electrophilic aromatic attack of phenylium ion on C6H6, (iii) of phenol radical cations C6H5OH+. via O radical addition on the benzene ring followed by ionization of the neutral product and finally (iv) of biphenyl-oxonium ions C12H11O+ and hydroxylbiphenyl-oxonium ions C_12H_{11}O_2^+ as end-products of the electrophilic attack of phenol ions on benzene and phenol, respectively. Finally, intriguing chemical paths involved in the corona discharge ionization of acetonitrile are also discussed.

Tosi, Paolo; Ascenzi, Daniela; Franceschi, Pietro; Guella, Graziano

2009-08-01

319

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

320

Ambient analysis by thermal desorption atmospheric pressure photoionization.  

PubMed

Ambient mass spectrometry has attracted substantial attention in recent years. Among ambient ionization methods, thermal desorption ionization stands out because of two attributes: (1) simplicity, rendering the technique suitable for in-field applications, and (2) ability to couple with a variety of gas-phase ionization methods thereby broadening the range of molecules that can be analyzed with this method. Here, we report on improving the performance of a direct analysis in real time (DART) source by implementing atmospheric pressure photoionization (APPI) downstream of the desorption region. At identical desorption and ion sampling conditions, APPI leads to detection of radical molecular ions from non-polar compounds that are absent from the spectra generated by DART alone. Moreover, a factor of 3-5 improvement in sensitivity is observed using APPI for positive ions commonly detected by DART and DART-APPI. Using helium and nitrogen as desorption gases, APPI shows identical performance regardless of desorption gas type. In contrast, a dramatic decrease in sensitivity is observed for DART operated with nitrogen compared to DART with helium. Comparable performance for DART and DART-APPI are observed in negative ion mode, although both show a drastic improvement in the absence of the Vapur interface. This interface creates a differentially pumped chamber prior to inlet of the mass spectrometer and reduces the mass spectrometer gas load when helium is used as desorption gas. PMID:23180079

Jorabchi, Kaveh; Hanold, Karl; Syage, Jack

2012-11-23

321

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

322

Filamentation in argon microwave plasma at atmospheric pressure  

SciTech Connect

Filamentation in an argon plasma is studied using a microwave cavity at atmospheric pressure. We show that the size and gas temperature of the filaments increase with the power absorbed by the plasma. The appearance of an additional filament occurs at specific values of the absorbed power. Each new filament appears with a smaller diameter than that of its parent filament but the sum of the diameters of all filaments evolves linearly with the absorbed power. A secondary filament emerges from a set of microfilaments created by a perturbation of the electric field (a slight increase in the incident power above a threshold value). This perturbation occurs over a larger radius than that of the parent filament. By resorting to modeling, we found that the filamentation process involves either a decrease in the effective frequency for momentum-transfer collisions, i.e., a lower electron temperature, or an increase in the electron density. We could show that a small change in the relative positions occupied by two filaments in the microwave cavity requires a strong variation in the electron temperature.

Cardoso, R. P.; Belmonte, T.; Noeel, C.; Kosior, F.; Henrion, G. [Departement CP2S, CNRS, Institut Jean Lamour, Nancy-Universite, UPV-Metz, Parc de Saurupt, CS 14234, 54042 Nancy Cedex (France)

2009-05-01

323

Atmospheric pressure microwave torch for synthesis of carbon nanotubes  

NASA Astrophysics Data System (ADS)

The microwave (mw) plasma torch at atmospheric pressure has been studied for carbon nanotube (CNT) synthesis. The depositions were carried out on silicon substrates with 5 15 nm thin iron catalytic overlayers from the mixture of argon, hydrogen and methane. The optical emission spectroscopy of the torch showed the presence of C2 and CH radicals as well as carbon and hydrogen excited atoms. The vicinity of the substrate influenced the relative intensities and increased the emission of C2. For fixed mw power, the temperature of the substrate strongly depended on its position with respect to the nozzle electrode and on the gas mixture, particularly the amount of H2. The speed of the substrate heating during an early deposition phase had a significant effect on the CNT synthesis. An abrupt increase of the temperature at the beginning increased the efficiency of the CNT synthesis. Areas of dense straight standing CNTs, 30 nm in average diameter, with approximately the same sized iron nanoparticles on their tops were found in accordance with the model of growth by plasma enhanced chemical vapour deposition. However, the deposit was not uniform and a place with only several nanometres thick CNTs grown on much larger iron particles was also found. Here, taking into account the gas temperature in the torch, 3100 3900 K, we can see similarities with the 'dissolution precipitation' model of the CNT growth by high temperature methods, arc or laser ablation.

Zajícková, L.; Eliás, M.; Jasek, O.; Kudrle, V.; Frgala, Z.; Matejková, J.; Bursík, J.; Kadlecíková, M.

2005-12-01

324

Infrared polarization spectroscopy of CO2 at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Polarisation spectroscopy (PS) was used to probe CO2 gas concentration in a CO2/N2 binary mixture at atmospheric pressure and ambient temperature. The CO2 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 H2 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 CO2 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, CO2 and N2O. 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

325

The manipulation of atmospheric pressure dielectric barrier plasma jets  

NASA Astrophysics Data System (ADS)

Atmospheric pressure plasma jets offer a unique route to transport reactive chemical species generated under highly non-equilibrium conditions to a remote downstream sample; as such, they have become the device of choice in many biological and materials processing applications. This contribution explores techniques to manipulate the propagation dynamics of the fast moving ionization front generated in a dielectric barrier plasma jet, after it is launched from the powered electrode. To achieve this, the electric field in the region through which the ionization front propagates is manipulated on a sub-microsecond timescale. It is demonstrated that the application of voltage pulses of varying duration and delay to supplementary electrodes placed along the axis of propagation and tangential to it facilitates a considerable level of control over the velocity, intensity and direction of the ionization front. In doing so, the flux of reactive species transported to a specific point on a downstream substrate can be electrically modulated on a pulse to pulse basis, a finding that could significantly extend the application scope of plasma jet devices.

Walsh, J. L.; Olszewski, P.; Bradley, J. W.

2012-06-01

326

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

327

Soil-gas entry into an experimental basement driven by atmospheric pressure fluctuations—Measurements, spectral analysis, and model comparison  

Microsoft Academic Search

To study the effects of atmospheric pressure fluctuations on the entry of radon and soil-gas contaminants into houses, we have simultaneously measured the changes in atmospheric pressure and the gas flow rate between the interior of an experimental basement structure and the underlying soil. Atmospheric pressure fluctuations draw soil gas into the experimental basement without the indoor-outdoor pressure differences commonly

Allen L. Robinson; Richard G. Sextro; William J. Fisk

1997-01-01

328

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

329

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); Neelin, J.D. [Univ. of California, Los Angeles, CA (United States)

1995-05-01

330

Relation of atmospheric pressure changes and the occurrences of acute myocardial infarction and stroke.  

PubMed

Previous studies have demonstrated variation in vascular events with respect to season and time of day. Changes in barometric pressure display daily and seasonal variations and could modulate the occurrence of vascular events. The objective of this study was to determine whether a relation exists between changes in barometric pressure and occurrence of stroke or acute myocardial infarction (AMI). A retrospective analysis of hospital admissions for AMI and stroke from 1993 to 1996 in central Texas was related to changes in atmospheric pressure that were obtained from the National Climatic Data Center. Patients who had AMI (n = 1,327) or stroke (n = 839) were identified from a computerized hospital database. Mean atmospheric pressure, greatest change in pressure, and rate of change in pressure per 24-hour period were computed. One-, 2-, and 3-day and seasonal groupings of cardiovascular events were related to corresponding changes in barometric pressure. The fall and winter seasons had the highest variability in atmospheric pressure readings. There was a significant correlation (p = 0.0083) between a decrease in atmospheric pressure and the occurrence of AMI the day after a pressure decrease, especially during the fall and winter seasons. No relation between stroke and atmospheric pressure was demonstrated. In conclusion, we conclude that rapid decreases in barometric pressure are associated with the occurrence of AMI but not of stroke. PMID:15979431

Houck, Philip D; Lethen, Jan E; Riggs, Mark W; Gantt, D Scott; Dehmer, Gregory J

2005-07-01

331

Resistance of the protozoan Colpoda maupasi to Martian conditions of atmospheric pressure and low partial pressure of oxygen.  

PubMed

Among the most important factors limiting the active life of animal organisms in Martian conditions are low atmospheric pressure and insignificant amounts of oxygen in the atmosphere (no more than 0.15% of the Earth's atmosphere). The experiments with aerobic protozoon C. maupasi have shown that in conditions of hermetically sealed chambers, for instance in 2.5 liter anaerostats, the protozoon can survive for a long time and reproduce in an atmosphere of air or nitrogen containing 1 or 0.0005% oxygen at a pressure from 15 mm Hg and higher. At the atmospheric pressure 10 mm Hg we observed a considerable decrease in the survival percentage and no reproduction. The exposure to 5 mm Hg resulted in a 100 per cent mortality of the protozoon. In a specially-constructed chamber "Photostat", in which current atmosphere pressure were automatically maintained during an experiment of many days, the reaction of the infusoria was somewhat different: they reproduced and existed not only at the pressure of 10-15 mm Hg, but also at 5 mm Hg, in an atmosphere of both air and nitrogen containing from 1 to 0.0005% O2. This indicates not only low-oxygen consumption of unicellular animals but also the capability of cells to extract some traces of this gas from the atmosphere. Low pressure and some traces of oxygen in the Martian atmosphere are not an impediment for the existence of some of the Earth's animals, such as the protozoon C. maupasi for example. PMID:11949684

Lozina-Lozinsky, L K; Bychenkova, V N

1969-01-01

332

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

333

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

334

Hollow needle-to-plate electrical discharge at atmospheric pressure  

NASA Astrophysics Data System (ADS)

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

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

1999-08-01

335

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

336

Focusing of Ions in Atmospheric Pressure Gases Using Electrostatic Fields.  

NASA Astrophysics Data System (ADS)

It has become increasingly important to improve the sensitivity of instruments that sample ions in atmospheric pressure gases from diffuse ion sources such as flames in air, ambient ions in air, and sprays, by introducing ions more efficiently into the analyzer region. Although the present state of mass spectroscopy is highly developed, a signal gain of a factor of two is deemed to be very significant. A prototype electrostatic lens system has been developed that demonstrates the feasibility of focusing ions toward a sampling orifice from various ion sources using spherically converging fields applied with a resistive thick film lens. The limit of a zero space charge ion source was investigated with a differential ion beam showing that gains in sensitivity can be on the order of 100 despite the observed field asymmetry. As part of this study, the ion flow in the micro-region approaching the vacuum orifice was analyzed, experimentally and theoretically, taking into account the combined effect of fluid motion and ion drift due to electric fields. Ions drifting toward the orifice plate are collected from an area larger than the orifice by a ratio which depends inversely on the field strength. Gains achievable by this system with an intense corona discharge ion source were examined to study effects of space charge. In order to maximize gain with the space charge fields present required the application of stronger focusing fields, strengthening the bias field, so that overall gain is reduced by the offsetting effect of the decrease in ion sampling area. Nevertheless, significant improvements in sensitivity, typically three times that of a non-focusing system, were observed. Thus the ion focusing system is of real benefit even with intense ion sources.

Potjewyd, John

337

Body temperature, shivering, blood pressure and heart rate during a standard cold stress in Australia and Antarctica  

PubMed Central

1. Four men of European descent were exposed naked to an air temperature of 10° C for 2 hr in Australia, and again after 24 weeks' residence at Mawson, Antarctica. 2. Their ability to maintain rectal temperature during the test cold exposure significantly improved at Mawson. Shivering and cold diuresis did not change. The response of skin temperature did not change significantly except for a small increase in toe temperature. Bradycardia caused by the cold exposure was significantly greater at Mawson, but the rise in blood pressure did not change. Spontaneous fluctuations in rectal temperature that occurred during the cold exposure were intensified at Mawson. 3. The results confirm those of a previous study at Mawson, and are attributed to general acclimatization to cold. It is suggested that tissue insulation increased as a result of enhanced vasoconstriction.

Budd, G. M.; Warhaft, N.

1966-01-01

338

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

339

Heat stress attenuates the increase in arterial blood pressure during the cold pressor test  

PubMed Central

The mechanisms by which heat stress impairs the control of blood pressure leading to compromised orthostatic tolerance are not thoroughly understood. A possible mechanism may be an attenuated blood pressure response to a given increase in sympathetic activity. This study tested the hypothesis that whole body heating attenuates the blood pressure response to a non-baroreflex-mediated sympathoexcitatory stimulus. Ten healthy subjects were instrumented for the measurement of integrated muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), heart rate, sweat rate, and forearm skin blood flow. Subjects were exposed to a cold pressor test (CPT) by immersing a hand in an ice water slurry for 3 min while otherwise normothermic and while heat stressed (i.e., increase core temperature ?0.7°C via water-perfused suit). Mean responses from the final minute of the CPT were evaluated. In both thermal conditions CPT induced significant increases in MSNA and MAP without altering heart rate. Although the increase in MSNA to the CPT was similar between thermal conditions (normothermia: ?14.0 ± 2.6; heat stress: ?19.1 ± 2.6 bursts/min; P = 0.09), the accompanying increase in MAP was attenuated when subjects were heat stressed (normothermia: ?25.6 ± 2.3, heat stress: ?13.4 ± 3.0 mmHg; P < 0.001). The results demonstrate that heat stress can attenuate the pressor response to a sympathoexcitatory stimulus.

Cui, Jian; Shibasaki, Manabu; Low, David A.; Keller, David M.; Davis, Scott L.

2010-01-01

340

Heat stress attenuates the increase in arterial blood pressure during the cold pressor test.  

PubMed

The mechanisms by which heat stress impairs the control of blood pressure leading to compromised orthostatic tolerance are not thoroughly understood. A possible mechanism may be an attenuated blood pressure response to a given increase in sympathetic activity. This study tested the hypothesis that whole body heating attenuates the blood pressure response to a non-baroreflex-mediated sympathoexcitatory stimulus. Ten healthy subjects were instrumented for the measurement of integrated muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), heart rate, sweat rate, and forearm skin blood flow. Subjects were exposed to a cold pressor test (CPT) by immersing a hand in an ice water slurry for 3 min while otherwise normothermic and while heat stressed (i.e., increase core temperature ~0.7°C via water-perfused suit). Mean responses from the final minute of the CPT were evaluated. In both thermal conditions CPT induced significant increases in MSNA and MAP without altering heart rate. Although the increase in MSNA to the CPT was similar between thermal conditions (normothermia: ?14.0 ± 2.6; heat stress: ?19.1 ± 2.6 bursts/min; P = 0.09), the accompanying increase in MAP was attenuated when subjects were heat stressed (normothermia: ?25.6 ± 2.3, heat stress: ?13.4 ± 3.0 mmHg; P < 0.001). The results demonstrate that heat stress can attenuate the pressor response to a sympathoexcitatory stimulus. PMID:20798269

Cui, Jian; Shibasaki, Manabu; Low, David A; Keller, David M; Davis, Scott L; Crandall, Craig G

2010-08-26

341

Influence of higher atmospheric pressure on the Martian radiation environment: Implications for possible habitability in the Noachian epoch  

Microsoft Academic Search

Noachian radiation environment not too hazardous for emergence of lifeHigher atmospheric pressure lowers absorbed dose rates on Martian surfaceDose rates for higher atmospheric pressure in magnitude of terrestrial values

B. Ehresmann; S. Burmeister; R. F. Wimmer-Schweingruber; G. Reitz

2011-01-01

342

Atmospheric pressure drives changes in the vertical distribution of biogenic free-phase gas in a northern peatland  

Microsoft Academic Search

Gas content in deep peat soils is larger and less variable than shallow peatIncreases in atmospheric pressure result in gas release from shallow peatDecreases in atmospheric pressure result in upward gas movement

Xavier Comas; Lee Slater; A. S. Reeve

2011-01-01

343

Influence of changes in atmospheric pressure on evaporation rates of low-loss helium cryostats  

Microsoft Academic Search

Experimental equipment for pressure control and evaporation rate measurement of a low-loss helium cryostat is described. The dependence of the helium gas outflow on the linearly varying pressure is presented for an NMR cryostat. The variations in measured helium evaporation rate were significantly high during experiments simulating usual atmospheric pressure changes. The measured quantities are compared to those evaluated by

P. Hanzelka; V. Musilová

1995-01-01

344

The seasonal variation of atmospheric pressure on Mars as affected by the south polar CAP  

Microsoft Academic Search

The daily mean pressures at two locations on Mars, observed over 57% of a Martian year, reveal a semiannual oscillation with a peak-to-peak difference that is 26% of the mean pressure. This intrinsically Martian phenomenon is caused by exchange of CO2 between the atmosphere and the winter polar caps. Evidence is presented that the difference in pressure at the two

S. L. Hess; R. M. Henry; J. E. Tillman

1979-01-01

345

DRYING OF WOOD BIOMASS AT HIGH PRESSURE STEAM ATMOSPHERE; EXPERIMENTAL RESEARCH AND APPLICATION  

Microsoft Academic Search

Imatran Voima Oy together with Technical Research Centre of Finland has carried out experimental research on fuel drying at high pressure steam atmosphere. The pilot dryer is a pressurized flash dryer. Since its commissioning in 1991, the dryer has been used for drying experiments of peat and wood biomass for about 1000 h. The dryer operates at 23 bar pressure

S. Hulkkonen; O. Heinonen; J. Tiihonen; R. Impola

1994-01-01

346

Thermodynamic analysis and experimental study of the effect of atmospheric pressure on the ice point  

NASA Astrophysics Data System (ADS)

We present a detailed thermodynamic analysis of the temperature of the ice point as a function of atmospheric pressure. This analysis makes use of accurate international standards for the properties of water and ice, and of available high-accuracy data for the Henry's constants of atmospheric gases in liquid water. The result is an ice point of 273.150 019(5) K at standard atmospheric pressure, with higher ice-point temperatures (varying nearly linearly with pressure) at lower pressures. The effect of varying ambient CO2 concentration is analyzed and found to be significant in comparison to other uncertainties in the model. The thermodynamic analysis is compared with experimental measurements of the temperature difference between the ice point and the triple point of water performed at elevations ranging from 145 m to 4302 m, with atmospheric pressures from 101 kPa to 60 kPa.

Harvey, A. H.; McLinden, M. O.; Tew, W. L.

2013-09-01

347

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

348

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

349

Ancient atmospheric CO2 pressures inferred from natural goethites  

Microsoft Academic Search

Data from goethites from an ironstone in the Upper Ordovician Neda Formation are presented which suggest that 440 Myr ago atmospheric P(CO2) was about 16 times higher than today. However, this enhanced level of atmospheric CO2 does not seem to have been accompanied by unusually warm temperatures in the tropics, and in fact may have been contemporaneous with high-latitude continental

Crayton J. Yapp; Harald Poths

1992-01-01

350

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...

351

Spectroscopic Investigation of Atmospheric Pressure Counterflow Diffusion Flames Inhibited by Halons.  

National Technical Information Service (NTIS)

Infrared spectra of atmospheric pressure counterflow diffusion flames inhibited by Halons and a few of their potential replacements are measured using Fourier transform spectroscopy. Results are compared to spectra of similar flame systems examined at low...

K. L. McNesby R. G. Daniel J. M. Widder A. W. Miziolek

1995-01-01

352

Negative differential resistance in MIM devices from vacuum to atmospheric pressure  

NASA Astrophysics Data System (ADS)

When a thin gold film is electroformed under an oil diffusion-pumped vacuum, the device subsequently displays a voltage controlled negative differential resistance (NDR) with electroluminescence (EL) and electron emission (EE). In this work we present experimental data, showing a device continuing to exhibit NDR when taken from vacuum to atmospheric pressure in either argon or nitrogen gas. NDR is observed over many voltage cycles with an accompanying EL, which is in contrast to the suppression of NDR which occurs on the first cycle for a deice in air at atmospheric pressure; NDR can only then be re-established by returning the device to vacuum. Therefore, as NDR can be achieved at atmospheric pressure in argon or nitrogen gas this indicates it is the presence of oxygen that inhibits the NDR conduction mechanism when a voltage is applied at atmospheric pressure.

Hooper, Peter D.; McHale, G.; Newton, M. I.

1996-04-01

353

Detection of Nonvolatile Species by Laser Desorption Atmospheric Pressure Mass Spectrometry.  

National Technical Information Service (NTIS)

This work examines the use of laser desorption as a means of volatilizing thermally labile compounds for detection in atmospheric pressure mass spectrometry. A number of different classes of compounds have been examined including amino acids, purine and p...

L. Kolaitis D. M. Lubman

1986-01-01

354

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

355

Preflame zone structure and main features of fuel conversion in atmospheric pressure premixed laminar hydrocarbon flames  

SciTech Connect

This report describes the structure study of the premixed hydrocarbon-oxidizer Bunsen flames burning at the atmospheric pressure and also the ones with some inhibitors added. Studies were performed on hexane, propane, methane, acetylene, and hexene flames.

Ksandopulo, G.I.

1995-08-25

356

Freezing and ice crystals formed in a cylindrical food model: part II. Comparison between freezing at atmospheric pressure and pressure-shift freezing  

Microsoft Academic Search

Cylindrical gelatin gels were pressure-shift frozen at different pressure levels (100, 150 and 200 MPa). Temperature and pressure profiles were compared and the maximum supercooling obtained after pressure release was evaluated. A comparison between the freezing steps at atmospheric pressure and those of pressure-shift freezing was carried out to compare the time steps during the processes. The degree of supercooling

D. Chevalier; A. Le Bail; M. Ghoul

2000-01-01

357

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

358

Analysis of nucleosides using the atmospheric-pressure solids analysis probe for ionization  

Microsoft Academic Search

Nucleosides are polar molecules and generally considered to be non-volatile. Therefore, electrospray ionization is the method of choice for analysis of these compounds by mass spectrometry. In this work, we demonstrate that the atmospheric-pressure solids analysis probe can be used to ionize modified and non-modified nucleosides. Analogously to atmospheric pressure chemical ionization, this ionization technique utilizes heat to vaporize the

Jef Rozenski

2011-01-01

359

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

360

Stability conditions of argon and helium gas mixtures in an atmospheric pressure plasma jet  

Microsoft Academic Search

Non-equilibrium plasmas can be generated by atmospheric pressure glow discharges, amongst others by atmospheric pressure plasma jets (APPJ), which feature a capacitive radio-frequency discharge between bare metallic electrodes.We investigated the stability conditions for discharges in an APPJ operated with helium–argon mixtures. Uniform ?-discharges can be sustained in mixtures ranging from pure helium to pure argon. The ignition voltage increases drastically

S. Haslinger; J. Laimer; H. Störi

2007-01-01

361

Surface treatment of metals using an atmospheric pressure plasma jet and their surface characteristics  

Microsoft Academic Search

We have treated the surfaces of Al, SUS and Cu metals using an atmospheric-pressure plasma jet generated by nitrogen and oxygen gases under the atmospheric pressure at room temperature. The plasma ignition occurred by flowing mixed gases between two coaxial metal electrodes, and the voltage was applied with impulse type and 16–20 kHz frequencies. The treated surfaces were basically characterized

M. C. Kim; S. H. Yang; J.-H. Boo; J. G. Han

2003-01-01

362

Dissociation of nitrogen in a pulse-periodic dielectric barrier discharge at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Nitrogen molecule dissociation in a pulse-periodic atmospheric-pressure dielectric barrier discharge is numerically analyzed. It is shown that the quenching rate of predissociation states at atmospheric pressure is relatively low and the production of nitrogen atoms in this case can be adequately described using the cross section for electron-impact dissociation of N2 molecules taken from the paper by P.C. Cosby [J. Chem. Phys. 98, 9544 (1993)].

Popov, N. A.

2013-05-01

363

Atmospheric pressure photoionization mass spectrometry for analysis of fatty acid and acylglycerol lipids  

Microsoft Academic Search

In this work, we optimize parameters and conditions for analysis of fatty acid ester and acylglycerol lipids by atmospheric pressure photoionization-mass spectrometry (APPI-MS). The investigated parameters include atmospheric pressure chemical ionization (APCI) nebulizer\\/vaporizer physical orientation and APPI lamp face position, solvent selections, mobile phase compositions and flow rates, cone voltages and probe temperatures. APPI sensitivity is found to be highly

Sheng-Suan Cai; Jack A. Syage

2006-01-01

364

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

365

Development of an energy controlled DC pulse discharge for atmospheric pressure plasma applications  

Microsoft Academic Search

Summary form only given. An atmospheric pressure plasma jet driven by energy controlled DC pulse has been developed. Unlike the most commonly used dielectric barrier atmospheric discharge sources, the proposed device utilize dielectric-free metal electrode with externally controllable ballast capacitor. Discharge energy per pulse can easily and precisely be controlled by voltage and capacitance of ballast capacitor. It is shown

Chang-Seung Ha; Dong-Hyun Kim; Hae June Lee; Ho-Jim Lee

2010-01-01

366

ICCD Imaging of Atmospheric Pressure Plasma Jet Behavior in Different Electrode Configurations  

Microsoft Academic Search

Nowadays, atmospheric pressure plasma jets using a dielectric-barrier discharge with an axial symmetry configuration attract the interest of many researchers. However, the mechanisms responsible for the generation of atmospheric plasma jets still remain unknown. In this paper, using intensified charge-coupled device images, we present the \\

Andrei V. Nastuta; Ionut Topala; Gheorghe Popa

2011-01-01

367

Elevated atmospheric partial pressure of CO2 and plant growth  

Microsoft Academic Search

Cotton plants were grown in late spring under full sunlight in glasshouses containing normal ambient partial pressure of CO2 (32±2Pa) and enriched partial pressure of CO2 (64±1.5Pa) and at four levels of nitrogen nutrition. Thirty-five days after planting, the total dry weights of high CO2-grown plants were 2- to 3.5-fold greater than plants grown in normal ambient CO2 partial pressure.

Suan-Chin Wong

1990-01-01

368

Qualification of Sub-Atmospheric Pressure Sensors for the Cryomagnet Bayonet Heat Exchangers of the Large Hadron Collider  

NASA Astrophysics Data System (ADS)

The superconducting magnets of the Large Hadron Collider (LHC) will be cooled at 1.9 K by distributed cooling loops working with saturated two-phase superfluid helium flowing in 107 m long bayonet heat exchangers located in each magnet cold-mass cell. The temperature of the magnets could be difficult to control because of the large dynamic heat load variations. Therefore, it is foreseen to measure the heat exchangers pressure to feed the regulation loops with the corresponding saturation temperature. The required uncertainty of the sub-atmospheric saturation pressure measurement shall be of the same order of the one associated to the magnet thermometers, in pressure it translates as +/-5 Pa at 1.6 kPa. The transducers shall be radiation hard as they will endure, in the worst case, doses up to 10 kGy and 1015 neutrons.cm-2 over 10 years. The sensors under evaluation were installed underground in the dump section of the SPS accelerator with a radiation environment close to the one expected for the LHC. The monitoring equipment was installed in a remote radiation protected area. This paper presents the results of the radiation qualification campaign with emphasis on the reliability and accuracy of the pressure sensors under the test conditions.

Bager, T.; Casas-Cubillos, J.; Jeanmonod, N.

2006-04-01

369

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

370

Cold Consolidation of Ball-Milled Titanium Powders Using High-Pressure Torsion  

NASA Astrophysics Data System (ADS)

Pure Ti (99.5 pct) powders after processing with ball milling (BM) were consolidated to disc-shaped samples with 10-mm diameter and 0.8-mm thickness at room temperature using high-pressure torsion (HPT). A relative density as high as 99.9 pct, high bending and tensile strengths of 2.55 to 3.45 and 1.35 GPa, respectively, and a moderate ductility of 8 pct with an ultrafine grained structure are achieved after cold consolidation with HPT, which exceed those of hot consolidation methods. X-ray diffraction (XRD) analysis showed that a phase transformation occurs from ? phase to ? phase during HPT under a pressure of 6 GPa as in bulk pure Ti, whereas no phase transformation is detected after processing with BM alone. It was confirmed that the strength and ductility are improved by a combined application of BM and HPT when compared with other severe plastic deformation methods applied to Ti and Ti-6 pct Al-4 pct V, so that no alloying elements are required for the achievement of a comparable strength and ductility.

Edalati, Kaveh; Horita, Zenji; Fujiwara, Hiroshi; Ameyama, Kei

2010-12-01

371

Sleep under extreme environments: Effects of heat and cold exposure, altitude, hyperbaric pressure and microgravity in space  

Microsoft Academic Search

Human sleep is sensitive to the individual's environment. The present review examines current knowledge of human sleep patterns under different environments: heat exposure, cold exposure, altitude, high pressure and microgravity in space. Heat exposure has two effects. In people living in temperate conditions, moderate heat loads (hot bath, sauna) prior to sleep provoke a delayed reaction across time (diachronic reaction)

Alain Buguet

2007-01-01

372

Hastening the Wheels of Change: International Cold War Pressure and Civil Rights Reform During the Truman Presidency  

Microsoft Academic Search

In the early Cold War arena, international pressure on the United States to live according to its ideological rhetoric enabled the Truman Administration to set a precedent for federal engagement in domestic civil rights reform. As the United States led the march to institutionalise human rights as the standard of moral legitimacy in the global arena, the country’s grisly record

Caley A. Robertson

2011-01-01

373

Acetic acid pulping of wheat straw under atmospheric pressure  

Microsoft Academic Search

Atmospheric acetic acid pulping of wheat straw was carried out. Pulping conditions and their effects on pulp properties were investigated in detail, and a comparison between acetic acid (AcOH) pulp and soda-anthraquinone (AQ) pulps of wheat straw was made of the chemical com- position, strength, and fiber morphology of the pulps. Wheat straw was successfully pulped and fractionated into pulp

Xue-Jun PanYoshihiro Sano

1999-01-01

374

Atmospheric Pressure Plasma Hydrophilic Modification of a Silicone Surface  

Microsoft Academic Search

The aim of this study was the creation of a silicone hydrophilic surface prior to bonding. Modifications in wettability and adhesion properties of silicone were performed with an atmospheric plasma torch (APPT). Surface energy variations of the substrate, both pristine and APPT-treated, were evaluated through contact angle measurements, studying the hydrophobic recovery of the samples up to 24 hours of

N. Encinas; R. G. Dillingham; B. R. Oakley; J. Abenojar; M. A. Martínez; M. Pantoja

2012-01-01

375

The Seasonal Variation of Atmospheric Pressure on Mars as Affected by the South Polar Cap  

Microsoft Academic Search

The daily mean pressures at two locations on Mars, observed over 57% of a martian year, reveal a semiannual oscillation with a peak-to-peak difference that is 26% of the mean pressure. This intrinsically martian phenomenon is caused by exchange of CO: between the atmosphere and the winter polar caps. The results are quantitatively in agreement with the simple model of

Seymour L. Hess; Robert M. Henry; James E. Tillman

1979-01-01

376

Safety benefits of using a sub-atmospheric pressure hydride gas source for MOCVD  

NASA Astrophysics Data System (ADS)

The reduced risks associated with storing toxic and flammable hydride gases on a high surface area substrate within a cylinder at sub-atmospheric pressures have been assessed. Tests have been performed on 2.2 and 49 L sub-atmospheric pressure cylinders filled to various pressures with arsine and phosphine to quantify the gas release rates that occur under conditions of simulated valve failure. Gas releases from sub-atmospheric pressure cylinders are diffusion rather than pressure-controlled and are found to be discrete rather than continuous. Average release concentrations measured at a ventilation air flow rate of 1.42 m3/min are well below the permissible exposure limit for both hydride gases over the test period. The results are compared to calculated release rates from high-pressure arsine and phosphine cylinders fitted with a restrictive flow orifice under otherwise similar conditions. The findings show that gas release rates from high-pressure cylinders are approximately four orders of magnitude higher than those from sub-atmospheric pressure cylinders. In addition to lowering the safety risks, benefits of adsorbed phase gas storage include the possibility of having increased volumes of hydride gas on site, improved process repeatability and reduced installation and operating costs.

Raynor, Mark W.; Houlding, Virginia H.; Frye, Russell; Olander, Karl

2004-12-01

377

Oxygen Spectroscopy Laser Sounding Instrument for Remote Sensing of Atmospheric Pressure  

Microsoft Academic Search

We report on the design and construction of an Oxygen spectroscopy laser sounding instrument designed to measure atmospheric pressure. The pressure sensing instrument (although useful for many applications) was designed as a calibration channel for a carbon dioxide instrument to meet the science requirements of NASA's ASCENDS Mission. The instrument was conceived and designed with a satellite application in mind

M. A. Stephen; J. Mao; J. B. Abshire

2008-01-01

378

Field-based determination of air diffusivity using soil air and atmospheric pressure time series  

Microsoft Academic Search

Air diffusivity in two zones over a 4.6-m interval of the unsaturated zone was determined through analysis of atmospheric pressure and soil air pressure time series. Regression analysis was used to calculate the ratio of amplitudes (admittance) and phase lag between these series at diurnal and semidiurnal frequencies. The admittance for each of the monitoring zones was close to unity

Stuart Rojstaczer; John P. Tunks

1995-01-01

379

Elevated atmospheric partial pressure of CO 2 and plant growth  

Microsoft Academic Search

Cotton and maize plants were grown under full sunlight in glass houses containing normal ambient partial pressure of CO2 (330±20 µbar) and enriched partial pressure of CO2 (640 ±15 µbar) with four levels of nitrogen nutrient. In 40 day old cotton plants grown in high CO2, there was a 2-fold increase in day weight and a 1.6-fold increase in leaf

S. C. Wong

1979-01-01

380

Looking at Heterogeneous Catalysis at Atmospheric Pressure Using Tunnel Vision  

Microsoft Academic Search

This paper addresses the “pressure gap” between traditional surface science experiments and catalysis under practical conditions. We review high-pressure, microflow experiments at elevated temperatures during the catalytic oxidation of CO. Using a specially constructed “Reactor-STM” we simultaneously determine the surface structure of a model catalyst by scanning tunneling microscopy and the reaction kinetics by online mass spectrometry. For both Pt(110)

Bas L. M. Hendriksen; Stefania C. Bobaru; Joost W. M. Frenken

2005-01-01

381

Effect of modified atmosphere packaging on oxidative changes in frozen stored cold water shrimp ( Pandalus borealis)  

Microsoft Academic Search

Shrimps caught at sea were boiled in seawater, air blast or nitrogen frozen, glazed and then packed in plastic bags with a low oxygen transmission rate. The bags were either flushed with nitrogen (modified atmosphere packaging) or with atmospheric air before sealing. The shrimps were then stored for up to 12 months in a freezer cabinet at ?17°C with fluctuating

L. S Bak; A. B Andersen; E. M Andersen; G Bertelsen

1999-01-01

382

Pressure-volume relationships above and below atmospheric pressure in the synovial cavity of the rabbit knee.  

PubMed Central

1. The pressure-volume relationship in the synovial cavity of the rabbit knee was investigated by the infusion of a non-absorbable oil into the cavity. 2. The pressure (P)-volume (V) curve was sigmoid. Its slope dP/dV (elastance) was steep at subatmospheric, physiological pressures, least steep at 5 cm H2O, and steepened progressively at higher, pathological pressures. 3. Elastance dP/dV was a good approximation to linear functions of P below atmospheric pressure and above 5 cm H2O. Each part of the pressure-volume relationship could therefore be described by an exponential expression. 4. Flexion of the joint increased pressure at a given volume. This was mainly due to steepening of the pressure-volume curve, and also partly due to a shift towards the pressure axis. 5. Pressure-volume curves determined by the infusion of normal saline or Krebs solution were grossly distorted, because these fluids were absorbed across the permeable synovium. 6. The physiological significance of the synovial pressure-volume curve is discussed, and mechanical explanations of the curve are suggested.

Knight, A D; Levick, J R

1982-01-01

383

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

2012-03-12

384

Application of Langmuir Probe Method to the Atmospheric Pressure Discharge Plasma  

SciTech Connect

The heat balance model in the probe tip applied to atmospheric pressure plasma is constructed. Considering the natural convective heat loss, the limitation of plasma density for probe application to such a plasma is estimated. The rough limit is about n{sub e} = 10{sup 18} m{sup -3}. Four kind of materials (Cu, SUS, W, Al) are used for probe tips, and are tested in DC atmospheric pressure discharge. Heat conductivity is found to be a more important property than melting point in design of probes in high pressure discharge. DC atmospheric pressure discharge plasma parameters are obtained with our test probes. Obtained density is the order of 10{sup 17} m{sup -3} and does not contradict with the above density limitation. Change of space potential in air/Ar plasma is also confirmed.

Matsuura, Hiroto; Matsumura, Yasuhiro; Nakano, Ken [Osaka Prefecture University, Gakuen-cho 1-1, Sakai Naka-ku, 599-8531 Osaka (Japan)

2008-12-31

385

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

386

A More Dramatic Container to Crush by Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

The familiar demonstration of collapsing a can by filling it with water vapor and then sealing it and allowing it to cool is improved by performing it with a 20-L steel solvent drum instead. This modification is significant because the steel drum is sufficiently sturdy to resist mechanical attempts to crush it. In contrast, the action of the atmosphere will dramatically collapse the drum almost completely.

Meyers, Robert D.; Yee, Gordon T.

1999-07-01

387

Acetic acid pulping of wheat straw under atmospheric pressure  

Microsoft Academic Search

Atmospheric acetic acid pulping of wheat straw was carried out. Pulping conditions and their effects on pulp properties were\\u000a investigated in detail, and a comparison between acetic acid (AcOH) pulp and soda-anthraquinone (AQ) pulps of wheat straw\\u000a was made of the chemical composition, strength, and fiber morphology of the pulps. Wheat straw was successfully pulped and\\u000a fractionated into pulp (cellulose),

Xue-Jun Pan; Yoshihiro Sano

1999-01-01

388

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

389

Blast field of microexplosives at atmospheric and reduced pressures  

NASA Astrophysics Data System (ADS)

We present the results of a study aimed at characterizing the impulse produced by the detonation of milligram charges of lead styphnate explosive at pressures ranging from 1 to 1000 mBar. A combined analytical/numerical approach based on either the vacuum expansion or the classical strong blast models is used to compute the impulse imparted by the explosion on a solid hemispherical surface. It is found that the vacuum expansion model agrees reasonably well with experiments performed at the lowest pressures, and that the predicted trends are indeed observed in practice. Poor agreement is observed with a strong blast model and this underscores the fact that its applicability depends on both the length scale of problem and the ambient pressure.

Martel, E.; Brouillette, M.

390

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

391

Generation Of Atmospheric Pressure Non-Thermal Plasma By Diffusive And Constricted Discharges In Rest And Flowing Gases (Air And Nitrogen)  

NASA Astrophysics Data System (ADS)

Weekly ionized non-thermal plasma (NTP) is of great interest for many applications because of its strong non-equilibrium state wherein an average electron energy Te exceeds markedly gas temperature Tg, i.e. electrons in the NTP are strongly overheated compared to neutral gas. Energetic electrons due to frequent collisions with the neutrals excite and dissociate effectively atoms and molecules of the plasma-forming gas that results in a creation of physically-, and bio-chemically active gaseous medium in a practically cold background gas. At present there are many kinds of plasma sources working at low and atmospheric pressure and using MW, RF, low frequency, pulsed and DC power supplies for NTP generation. The NTP at atmospheric pressure is of considerable interest for practice. A reason is that sustaining the NTP at atmospheric pressure at first allows us to avoid the use of expensive vacuum equipment and second gives opportunity to use the NTP for treatment of the exhausted gases and polluted liquids. The second opportunity cannot be realized at all with use of the NTP at low pressure. Main subject of this talk is low current atmospheric pressure gas discharges powering with DC power supplies. Plasma forming gases are air and nitrogen which are much cheaper compared to rare gases like He or Ar. Besides, great interest to molecular nitrogen as plasma forming gas is caused first of all its unique capability to accumulate huge energy in vibration, electron (metastables) and dissociated (atomic) states providing high chemical reactivity of the activated nitrogen. All active particles mentioned above have a long lifetime, and they can be therefore transported for a long distance away from place of their generation. Different current modes (diffusive and constricted) of these discharges are discussed. Experimental and numerical results on generation of chemically active species in the diffusive and constricted mode are presented. Some data on the usage of the atmospheric pressure NTP for gas cleanup, surface treatment and sterilization are given.

Akishev, Y.; Grushin, M.; Karalnik, V.; Kochetov, I.; Napartovich A.; Trushkin N.

2010-07-01

392

Atmospheric Airborne Pressure Measurements using the Oxygen A Band for the ASCENDS Mission  

NASA Astrophysics Data System (ADS)

We report on airborne atmospheric pressure measurements using fiber-based laser technology and the oxygen A-band at 765 nm. Remote measurements of atmospheric temperature and pressure are needed for NASA's Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission to measure atmospheric CO2. Accurate measurements of tropospheric CO2 on a global scale are very important in order to better understand its sources and sinks and to improve our predictions of climate change. The ultimate goal of ASCENDS, is to derive the CO2 dry mixing ratio in the atmosphere in terms of mole fraction in unit of parts-per-million (ppmv). Thus, both CO2 and the dry air number of molecules in the atmosphere are needed in deriving this quantity. O2 is a stable molecule that 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 mixing ratio. 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 erbium fiber optic and non-linear optics technology to generate 765 nm laser radiation coincident with the Oxygen A-band. Our pulsed, time gated approach 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 expected O2 lineshapes and derives the pressure by minimizing the error between the observations and model.

Riris, H.; Rodriguez, M.; Allan, G.; Hasselbrack, W.; Mao, J.; Abshire, J. B.; Stephen, M.

2011-12-01

393

Characterization of carbon CVD coatings near atmospheric deposition pressure  

Microsoft Academic Search

Pyrolytic carbon coatings show excellent hermetic properties and can be applied to optical fibers during the draw process by thermally activated chemical vapor deposition (CVD). This study investigates the relationship between carbon growth rates, microstructure, and deposition conditions at 600 torr chamber pressure. The films are grown from methane, propane and butane precursors on stationary 3 mm quartz rods. Hydrocarbon

Craig A. Taylor; Wilson K. Chiu

2003-01-01

394

Evolution of Bullets in Helium Atmospheric Pressure Plasma Jet  

Microsoft Academic Search

Plasma medicine field development triggered intense research efforts to understand the physics and chemistry of at- mospheric pressure plasma jets. High-speed photography offers unique information on plasma continuity and upon specific struc- tures with very short life time, typically in the nanosecond range. Using this technique, we have shown that the helium plasma jet contains two distinct types of bullets

Ionut Topala; Nicoleta Dumitrascu

2011-01-01

395

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

396

Blast field of microexplosives at atmospheric and reduced pressures  

Microsoft Academic Search

We present the results of a study aimed at characterizing the impulse produced by the detonation of milligram charges of lead styphnate explosive at pressures ranging from 1 to 1000 mBar. A combined analytical\\/numerical approach based on either the vacuum expansion or the classical strong blast models is used to compute the impulse imparted by the explosion on a solid

E. Martel; M. Brouillette

2005-01-01

397

Growth of Carnobacterium spp. from permafrost under low pressure, temperature, and anoxic atmosphere has implications for Earth microbes on Mars.  

PubMed

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 CO(2)-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. PMID:23267097

Nicholson, Wayne L; Krivushin, Kirill; Gilichinsky, David; Schuerger, Andrew C

2012-12-24

398

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

399

Deposition of silicon dioxide films with a non-equilibrium atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

Silicon dioxide films were grown using an atmospheric-pressure plasma jet that was produced by flowing oxygen and helium between two coaxial metal electrodes that were driven by 13.56 MHz radio frequency power. The plasma exiting from between the electrodes was mixed with tetraethoxysilane (TEOS), and directed onto a silicon substrate held at 115-350 °C. Silicon dioxide films were deposited at rates ranging from 20±2 to 300±25 nm min-1. The deposition rate increased with decreasing temperature and increasing TEOS pressure, oxygen pressure and RF power. For the latter two variables, the rate increased as follows: Rd?P0.3O2(RF)1.4. Films grown at 115 °C were porous and contained adsorbed hydroxyl groups, whereas films grown at 350 °C were smooth, dense and free of impurities. These results suggest that the mechanism in the atmospheric pressure plasma is the same as that in low-pressure plasmas.

Babayan, S. E.; Jeong, J. Y.; Schütze, A.; Tu, V. J.; Moravej, Maryam; Selwyn, G. S.; Hicks, R. F.

2001-11-01

400

Atmospheric pressure laser ionization (APLI) coupled with Fourier transform ion cyclotron resonance mass spectrometry applied to petroleum samples analysis: comparison with electrospray ionization and atmospheric pressure photoionization methods.  

PubMed

The analysis of crude oil samples remains a tough challenge due to the complexity of the matrix and the broad range of physical and chemical properties of the various individual compounds present. In this work, atmospheric pressure laser ionization (APLI) is utilized as a complementary tool to other ionization techniques for crude oil analysis. Mass spectra obtained with electrospray ionization (ESI) and atmospheric pressure photoionization (APPI) are compared. APLI is primarily sensitive towards non-polar aromatic hydrocarbons, which are generally present in high amounts especially in heavy crude oil samples. The ionization mechanisms of APLI vs. APPI are further investigated. The results indicate the advantages of APLI over established methods like ESI and APPI. The application of APLI in combination with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is thus demonstrated to be a powerful tool for the analysis of aromatic species in complex crude oil fractions. PMID:21769956

Panda, Saroj K; Brockmann, Klaus-J; Benter, Thorsten; Schrader, Wolfgang

2011-08-30

401

Spatially resolved diagnostics on a microscale atmospheric pressure plasma jet  

Microsoft Academic Search

Despite enormous potential for technological applications, fundamentals of stable non-equilibrium micro-plasmas at ambient pressure are still only partly understood. Micro-plasma jets are one sub-group of these plasma sources. For an understanding it is particularly important to analyse transport phenomena of energy and particles within and between the core and effluent of the discharge. The complexity of the problem requires the

V. Schulz-von der Gathen; L. Schaper; N. Knake; S. Reuter; K. Niemi; T. Gans; J. Winter

2008-01-01

402

Infrared emission spectroscopy of glow discharge formed in low pressure atmospheric gases  

NASA Astrophysics Data System (ADS)

Laboratory study was conducted on the molecular and atomic emissions which are considered detectable in the IR radiative background of the upper atmosphere. The IR spectra of glow discharge emission formed in air and other atmospheric constituent gases of 0.1-Torr pressure and a 30-m long column were surveyed using the technique of Fourier spectroscopy. Several features hitherto unobserved were detected in our survey study.

Sakai, H.; Hansen, P.; Esplin, M.; Johansson, R.; Peltola, M.; Strong, J.

1982-01-01

403

Visualization of Revolving Modes in RF and MW Nonthermal Atmospheric Pressure Plasma Jets  

Microsoft Academic Search

The high-speed sequence imaging of two different atmospheric pressure plasma jets illuminates the low-frequency dynamics of discharge filaments. Usually, atmospheric plasma jets consist of several contracted filaments occurring in the active zone of the plasma randomly in space and stochastically in time. However, particular plasma excitation schemes support collective regimes where the filaments are self-organized at large spatial and temporal

Jan Schafer; Petr Vasina; Jaroslav Hnilica; Rüdiger Foest; Vít Kudrle; Klaus-Dieter Weltmann

2011-01-01

404

Microwave air plasma source at atmospheric pressure: Experiment and theory  

NASA Astrophysics Data System (ADS)

An experimental and theoretical investigation of the axial structure of a surface wave (2.45 GHz) driven atmospheric plasma source in air with a small admixture (1%) of water vapor has been performed. Measurements of the gas temperature and of the intensities of the O(777.4 nm), O(844.6 nm), and O(630 nm) atomic lines and the NO(?) molecular band versus input power and axial position were carried out. Amplitude and phase sensitive measurements have also been performed to derive the surface wave dispersion characteristics. The experimental results are analyzed in terms of a one-dimensional theoretical model based on a self-consistent treatment of particle kinetics, gas dynamics, and wave electrodynamics. The predicted gas temperature and emission line intensities variations with power and axial position are shown to compare well with experiment. ``Hot'' excited O atoms (with kinetic energy ~2 eV) have been detected.

Tatarova, E.; Dias, F. M.; Felizardo, E.; Henriques, J.; Pinheiro, M. J.; Ferreira, C. M.; Gordiets, B.

2010-12-01

405

Source of Temperature and Pressure Pulsations during Sessile Droplet Evaporation into Multicomponent Atmospheres.  

PubMed

During sessile droplet evaporation, studies with IR thermography and shadowgraphs have indicated temperature pulsations. We confirm those observations with microthermocouples, but microthermocouples also indicate temperature pulsations in the atmosphere of the droplet. The pressure in this atmosphere pulsated as well and was correlated with the temperature pulsations in the droplet. Also, we find that if a droplet evaporates into its own vapor, there are no temperature or pressure pulsations. The pulsations occur only if the droplet evaporates into an atmosphere with a component having a heat of solution with the droplet when it adsorbs-absorbs. None of the currently proposed mechanisms for the temperature pulsations provide an explanation for the coupling between the temperature pulsations in the droplet and the vapor-phase pressure pulsations, and for the absence of the pulsations when the system is single-component. As a mechanism for the pulsations, we propose that when a droplet is exposed to an atmosphere containing a component that has a heat of solution with the droplet, energy will be released from adsorption-absorption. This energy will cause pulsations in the evaporation flux, and these pulsations could cause the observed temperature and pressure pulsations. We examine this mechanism by showing that, if the measured temperature pulsations in a water droplet exposed to a methanol atmosphere are used as the input to a theory of evaporation kinetics (statistical rate theory), the pressure pulsations of the water vapor in the methanol atmosphere are predicted and agree with those measured with a quadrupole mass analyzer. When the inputs and outputs are reversed in the theory, we find that the temperature pulsations in the droplet are correctly predicted from the measured water vapor pulsations in the atmosphere. PMID:24079943

Persad, Aaron H; Sefiane, Khellil; Ward, Charles A

2013-10-16

406

Atmospheric Pressure-Induced Effects in the VUV Absorption Spectrum of C2H2  

NASA Astrophysics Data System (ADS)

It is well known that high pressure in an absorbing system can cause line broadening, line shifts, and pressure-induced transitions. Real planetary atmospheres consist of a mixture of various molecules. It is well known that the pressure effects vary in nature depending on the characteristics of the collision constituents. It is thus desirable to measure the cross sections of molecules under the planetary atmosphere conditions of interest. For example, in Jupiter's atmosphere typical absorber (e.g., C2H2) abundances vary from 0.2 cm-atms to 5 cm-atms in the presence of H2. The pressure of H2 is in fact about 10(7) times that of C2H2. We have investigated the absorption cross section of C2H2 in the presence of Ar and N2 up to the highest pressure possible using our existing apparatus, namely, a factor of about 1.6 x 10(5) times that of C2H2. We have initially carried out a study of pressure effects in the 150-153.5 nm, 124-126 nm, 119.5-123.0 nm, and 116.5-118.5 nm regions, which covers three different Rydberg transitions of C2H2. In the case of Ar only pressure broadening effects are observed whereas, in the case of N2, pronounced pressure-induced transitions are also observed in addition to the well known spectral broadening. In the future we will investigate the pressure effects on C2H2 in the presence of H2. The preliminary results obtained to date will be presented. This research is based on work supported by the NASA Planetary Atmospheres Program under Grant NAG5-11042.

Chen, F.; Wu, R.; Judge, D.

2002-09-01

407

Biomedical Applications of Low Temperature Atmospheric Pressure Plasmas to Cancerous Cell Treatment and Tooth Bleaching  

NASA Astrophysics Data System (ADS)

Low temperature atmospheric pressure plasmas have attracted great interests and they have been widely applied to biomedical applications to interact with living tissues, cells, and bacteria due to their non-thermal property. This paper reviews the biomedical applications of low temperature atmospheric pressure plasmas to cancerous cell treatment and tooth bleaching. Gold nanoparticles conjugated with cancer-specific antibodies have been introduced to cancerous cells to enhance selective killing of cells, and the mechanism of cell apoptosis induced by plasma has been investigated. Tooth exposed to helium plasma jet with hydrogen peroxide has become brighter and the productions of hydroxyl radicals from hydrogen peroxide have been enhanced by plasma exposure.

Lee, Jae Koo; Kim, Myoung Soo; Byun, June Ho; Kim, Kyong Tai; Kim, Gyoo Cheon; Park, Gan Young

2011-08-01

408

BRIEF COMMUNICATION: An alternative source for generating atmospheric pressure non-thermal plasmas  

NASA Astrophysics Data System (ADS)

This communication presents an alternative source for the generation of non-thermal plasmas at atmospheric pressure. It is based on a very simple electric diagram that generates, on the plasma electrode, an electric field sufficiently high to ionize various gases (helium, argon or even air), which flow at atmospheric pressure. The dc power supply is lower than 10 V, the frequency of the electric field is in the range 0.1-1 MHz and the plasma power is less than 1 W. The plasma is generated using only one electrode. It has all the characteristics of non-thermal plasmas.

Anghel, S. D.; Simon, A.

2007-08-01

409

Atmospheric Pressure Plasma Electron Density Measurments by Magnetohydrodynamic Generator (MHDG) Method  

NASA Astrophysics Data System (ADS)

In this work atmospheric pressure plasma discharge was immersed in a hollow box which is called as manetohydrodynamic generator (MHDG). This box consists of two conductors and two insulating edges. Permanent magnets were placed on the insulating edges for a magnetic field which is perpendicular to the discharge flow. Hall-effect voltage was observed between the opposite conductive edges of the MHDG. 1 kHz atmospheric pressure helium discharge density was calculated as 4.9x10^13 cm-3 by using Hall-effect voltage and the discharge current. For different plasma conditions plasma density calculations will be given.

Gulec, Ali; Bozduman, Ferhat; Teke, Erdogan; Oksuz, Lutfi

2012-10-01

410

Spectroscopic measurement of electric field in atmospheric-pressure plasma jet operating in bullet mode  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure helium plasma jet operating in the bullet/streamer mode has been studied using optical emission spectroscopy. Electric field strength distribution is measured using Stark polarization spectroscopy of He I 492.19 nm line. It is shown that the electric field is almost constant along the jet axis. Measured electric field distribution is in agreement with theoretical predictions of streamer propagation in helium jets at atmospheric pressure. Obtained radial distribution of the axial electric field shows that the ring-shaped structure of the light emission is a consequence of such electric field distribution.

Sretenovi?, Goran B.; Krsti?, Ivan B.; Kova?evi?, Vesna V.; Obradovi?, Bratislav M.; Kuraica, Milorad M.

2011-10-01

411

Atmospheric-pressure argon/oxygen plasma-discharge source with a stepped electrode  

SciTech Connect

The nonequilibrium glow discharge in argon mixed with oxygen at atmospheric pressure was generated in a parallel plate reactor with a stepped electrode powered by a 13.56 MHz radio-frequency power supplier. The stepped-electrode reactor consists of a narrow and wide gap structure. A strong electric field occurred at the narrow gap region preionizes Ar/O{sub 2} gas and assists to generate a large volumetric plasma in the wide gap region. Therefore, the stepped-electrode reactor makes it easy to operate Ar/O{sub 2} glow discharge, providing a stable, uniform, and broad plasma jet at atmospheric pressure.

Lim, Jin-Pyo; Uhm, Han S.; Li Shouzhe [Department of Molecular Science and Technology, Ajou University, San 5 Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of); State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams and Department of Physics, Dalian University of Technology, Dalian 116024 (China)

2007-01-29

412

Promoted cell and material interaction on atmospheric pressure plasma treated titanium  

NASA Astrophysics Data System (ADS)

Surface carbon contamination is a natural phenomenon. However, it interferes with cell-biomaterial interaction. In order to eliminate the interference, atmospheric pressure plasma treatment was employed. Dielectric barrier discharge treatment of titanium surface for less than 10 min turned titanium super-hydrophilic. Adsorption of fibronectin which is the major cell adhesive protein increased after plasma treatment. Cell attachment parameters of osteoblast cells such as population, cell area, perimeter, Feret's diameter and cytoskeleton development were also enhanced. Cell proliferation increased on the plasma treated titanium. In conclusion, dielectric barrier discharge type atmospheric pressure plasma system is effective to modify titanium surface and the modified titanium promotes cell and material interactions.

Han, Inho; Vagaska, Barbora; Seo, Hyok Jin; Kang, Jae Kyeong; Kwon, Byeong-Ju; Lee, Mi Hee; Park, Jong-Chul

2012-03-01

413

Protein patterning utilizing region-specific control of wettability by surface modification under atmospheric pressure  

NASA Astrophysics Data System (ADS)

Wettability control can be crucial in improving the uniformity of selective protein immobilization in high-density microarrays. In this study, we propose an atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD)-based method in conjunction with photolithography to implement region-specific control of wettability on Si substrate. The proposed PECVD method under atmospheric pressure condition would be a useful alternative of conventional reactive plasma-based treatments methods requiring vacuum condition for uniform protein patterning. Layers with dissimilar wettability and roughness prepared by AP-PECVD process using tetraethoxysilane (TEOS) or TEOS-O2 as precursors could realize uniform protein patterning in a micrometer-scale.

Lee, Donghee; Kwon, Min-Sung; Hyun, Ji-Chul; Jun, Chang-Duk; Chung, Euiheon; Yang, Sung

2013-09-01

414

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

415

Feeling the cold: atmospheric CO 2 enrichment and the frost sensitivity of terrestrial plant foliage  

Microsoft Academic Search

Quantitative palaeoclimate reconstructions from plant fossils using the nearest living relative (NLR) approach axiomatically assume that the climatic limits of plant distributions have largely remained unchanged over at least the past 250 Myr. However, throughout much of the Mesozoic the atmospheric CO2 concentration is predicted to have been several times greater than the present day, and long-term (?5 yr) experimental

D. J Beerling; A. C Terry; C Hopwood; C. P Osborne

2002-01-01

416

Striated microdischarges in an asymmetric barrier discharge in argon at atmospheric pressure  

SciTech Connect

The investigation of striated microdischarges in barrier discharges in argon at atmospheric pressure is reported. Microdischarges were investigated by means of electrical measurements correlated with intensified CCD camera imaging. The scaling law theory known from low-pressure glow discharge diagnostics was applied in order to describe and explain this phenomenon. The investigated microdischarge is characterized as a transient atmospheric-pressure glow discharge with a stratified column. It can be described by similarity parameters i/r{approx_equal}0.13 A/cm, pr{approx_equal}5 Torr cm, and 3<{lambda}/r<5 with the current i, pressure p, interval of subsequent striations {lambda}, and radius of the plasma channel r. An attempt to describe the mechanism of creation of a striated structure is given, based on an established model of the spatial electron relaxation.

Hoder, Tomas; Loffhagen, Detlef; Wilke, Christian; Grosch, Helge; Schaefer, Jan; Weltmann, Klaus-Dieter; Brandenburg, Ronny [Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, D-17489 Greifswald (Germany)

2011-10-15

417

Modification of the structure of cold-worked Zr2. 5 wt % Nb nuclear reactor pressure tube material  

Microsoft Academic Search

The metallography and mechanical properties of cold-worked Zr-2.5 wt % Nb alloy nuclear reactor pressure tubing are described in relation to the phases present after various heat treatments in the (..cap alpha.. + ..beta..\\/sub Zr\\/) and (..cap alpha.. + ..beta..\\/sub Nb\\/) phase regions. A heat treatment is recommended that produces room-temperature mechanical properties that are almost as good as those

D. O. Northwood; W. L. Fong

1980-01-01

418

Signal processing of diurnal and semidiurnal variations in radon and atmospheric pressure: A new tool for accurate in situ measurement of soil gas velocity, pressure gradient, and tortuosity  

Microsoft Academic Search

Signal processing of diurnal and semidiurnal variations of both atmospheric pressure and radon concentration in soil gases is shown to be useful for estimating soil gas transport parameters. The two daily-cycle peaks at 12- and 24-hour periods in the Power Spectral Density (PSD) of atmospheric pressure seem to be present everywhere on Earth's surface, and it is the effect of

Jean-Louis Pinault; Jean-Claude Baubron

1997-01-01

419

Decontamination of Chemical\\/Biological Warfare (CBW) Agents Using an Atmospheric Pressure Plasma Jet (APPJ)  

Microsoft Academic Search

The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure, uniform glow discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g. He\\/O_2\\/H_2O) which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas

Hans W. Herrmann

1998-01-01

420

Decontamination of chemical and biological warfare (CBW) agents using an atmospheric pressure plasma jet (APPJ)  

Microsoft Academic Search

The atmospheric pressure plasma jet (APPJ) [A. Schütze et al., IEEE Trans. Plasma Sci. 26, 1685 (1998)] is a nonthermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He\\/O2\\/H2O), which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode

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

1999-01-01

421

Decontamination of chemical and biological warfare (CBW) agents using an atmospheric pressure plasma jet (APPJ)  

Microsoft Academic Search

The atmospheric pressure plasma jet (APPJ) [A. Schu¨tze &etal;, IEEE Trans. Plasma Sci. 26, 1685 (1998)] is a nonthermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He\\/O2\\/H2O), which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered

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

1999-01-01

422

Micro-structured electrode arrays: atmospheric pressure plasma processes and applications  

Microsoft Academic Search

Micro-structured electrode (MSE) arrays allow to generate large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode dimensions in the micro-range realized by means of modern micro-machining and galvanic techniques are small enough to generate sufficiently high electric field strengths to ignite gas discharges applying only moderate radio frequency (13.56 MHz) voltages (80–390 V in

L. Baars-Hibbe; P. Sichler; C. Schrader; C. Geßner; K.-H. Gericke; S. Büttgenbach

2003-01-01

423

Methane and Ethane Decomposition in an Atmospheric-Pressure Plasma Jet  

Microsoft Academic Search

This paper reports on studies obtained from RF-driven atmospheric-pressure plasma-jet excitation of methane and ethane. Differentiation with other works is achieved in that others have considered hydrocarbon decomposition at either low pressure or high temperature. In our experiments, we can clarify the effect of pure-plasma treatment of hydrocarbons, as opposed to the thermal effect of gas heating that results in

Rodrigo Sanchez-Gonzalez; Yongho Kim; Louis A. Rosocha; Sara Abbate

2007-01-01

424

Radio-Frequency-Driven Atmospheric-Pressure Plasmas in Contact with Liquid Water  

Microsoft Academic Search

Atmospheric-pressure plasmas were produced on the surface of liquid water by radio-frequency (RF) power supply. A quartz chamber with an off-center inner electrode was used to generate discharges with a wide range of filling gas pressures. When the chamber was filled with fuel gas and liquid water and a sufficient RF power was supplied to the system, plasmas were observed

Katsuhisa Kitano; Hironori Aoki; Satoshi Hamaguchi

2006-01-01

425

Heritability of Blood Pressure Responses to Cold Pressor Test in a Chinese Population  

PubMed Central

BACKGROUND Genetic determinants of blood pressure (BP) responses to the cold pressor test (CPT), a phenotype associated with risk of hypertension and cardiovascular disease has not been well studied. METHODS We examined the heritability of BP response to CPT in 1,994 subjects from 627 families in rural north China. BP was measured prior to and at 0, 1, 2, and 4 minutes after the participants immersed their hand in ice water for 1 minute. Heritabilities of baseline BP and responses at 0 minutes, maximum response, and area-under-the-curve during CPT were computed using a variance components method. Additionally, bivariate heritabilities were calculated to test the existence of shared genetic determinants between baseline BP and responses to CPT. RESULTS Heritabilities of baseline BP and responses to CPT were estimated from 14% to 35%, which all significantly differed from 0 (p?0.002). Genetic correlations (standard error) due to the same genes between baseline BP and responses to CPT ranged from ?0.07 (0.14) to 0.21 (0.15), which were not significantly different from 0. Genetic correlations between reactivity and recovery were 0.67 (0.10) and 0.59 (0.10) for systolic and diastolic BP, respectively, which were significantly different from 0. CONCLUSIONS We concluded: 1) baseline BP and BP responses to CPT had strong genetic determinants; 2) baseline BP and BP response to CPT did not share the same genetic components; and 3) BP reactivity and recovery shared the same genetic components. These findings may lead to a better understanding of the genetic mechanism of BP responses to CPT.

Mei, Hao; Gu, Dongfeng; Rice, Treva K.; Hixson, James E.; Chen, Jing; Jaquish, Cashell E.; Zhao, Qi; Chen, Chung-Shiuan; Chen, Ji-Chun; Gu, C. Charles; Kelly, Tanika N.; He, Jiang

2010-01-01

426

Aerobic exercise attenuates blood pressure reactivity to cold pressor test in normotensive, young adult African-American women.  

PubMed

Exaggerated blood pressure reactivity to behavioral stress has been observed in the African-American population, and such a pressor response is believed to play a role in hypertension. Regular aerobic exercise has been shown to exert an anti-hypertensive effect, and this may alter the blood pressure hyperreactivity observed in African Americans. To test the hypothesis that aerobic exercise attenuates pressor reactivity in African Americans, we studied eight healthy aerobically-trained normotensive African-American females and five similar sedentary females. The stress stimuli consisted of the cold pressor test with the foot immersed in ice water for two minutes. The aerobic exercise training protocol consisted of six weeks of jogging at 60-70% of peak oxygen uptake (VO2peak), three days/week for 35 min/exercise session. Systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, heart rate, cardiac output, total peripheral resistance, and forearm blood flow were measured. Manifestation of a training effect was illustrated by a 24.1 +/- 0.2% increase in VO2peak (26.9 +/- 1.2 mL x kg(-1) min(-1) vs 35.4 +/- 1.6 mL x kg(-1) min(-1)) (P<.05). Within the exercise-trained group there was a 6.3 +/- .15% decrease in systolic pressure (129 +/- 4.6 mm Hg vs. 121 +/- 5.4 mm Hg) (P<.05), and a 5.0 +/- .05% decrement in mean arterial blood pressure (99 +/- 3.3 mm Hg vs 94 +/- 3.6 mm Hg) (P<.05) during the cold pressor test. Pressor reactivity to cold stress did not change in the untrained group. Measures of heart rate, cardiac output, total peripheral resistance, and forearm blood flow were unaltered during conditions of the cold pressor test. We conclude that aerobic exercise attenuates the blood pressure reactivity to behavioral stress in young, adult normotensive African-American females. A lifestyle change such as exercising may play a role in reducing the risk of hypertension in African-American women. PMID:10355479

Bond, V; Mills, R M; Caprarola, M; Vaccaro, P; Adams, R G; Blakely, R; Roltsch, M; Hatfield, B; Davis, G C; Franks, B D; Fairfax, J; Banks, M

1999-01-01

427

Antioxidant enzyme activities in strawberry fruit exposed to high carbon dioxide atmospheres during cold storage  

Microsoft Academic Search

The effects of storage, in air or a 20% CO2 in air (16.8% O2) atmosphere for 12d at 2°C, on antioxidant enzymes of strawberry fruit (Fragaria x ananassa Duch. cv. ‘Jewel’) were investigated. The concentrations of acetaldehyde, ethanol and ethyl acetate associated with fermentation were measured, and the activities of peroxidase (POX), catalase (CAT) and superoxide dismutase (SOD) assayed. Ethanol,

J. Pablo Fernández-Trujillo; Jacqueline F. Nock; Christopher B. Watkins

2007-01-01

428

The interplanetary magnetic field influences mid-latitude surface atmospheric pressure  

NASA Astrophysics Data System (ADS)

The existence of a meteorological response in the polar regions to fluctuations in the interplanetary magnetic field (IMF) component By is well established. More controversially, there is evidence to suggest that this Sun-weather coupling occurs via the global atmospheric electric circuit. Consequently, it has been assumed that the effect is maximized at high latitudes and is negligible at low and mid-latitudes, because the perturbation by the IMF is concentrated in the polar regions. We demonstrate a previously unrecognized influence of the IMF By on mid-latitude surface pressure. The difference between the mean surface pressures during times of high positive and high negative IMF By possesses a statistically significant mid-latitude wave structure similar to atmospheric Rossby waves. Our results show that a mechanism that is known to produce atmospheric responses to the IMF in the polar regions is also able to modulate pre-existing weather patterns at mid-latitudes. We suggest the mechanism for this from conventional meteorology. The amplitude of the effect is comparable to typical initial analysis uncertainties in ensemble numerical weather prediction. Thus, a relatively localized small-amplitude solar influence on the upper atmosphere could have an important effect, via the nonlinear evolution of atmospheric dynamics, on critical atmospheric processes.

Lam, M. M.; Chisham, G.; Freeman, M. P.

2013-12-01

429

CO 2 Reforming of CH 4 by Atmospheric Pressure ac Discharge Plasmas  

Microsoft Academic Search

Partial oxidative reactions of methane by carbon dioxide have been studied using atmospheric pressure alternating current plasmas. The reactions were carried out using a Y-type reactor with metal rods as the inner electrodes inside quartz tubes and aluminum foil wrapped around quartz tubes as the outer electrodes. The waveforms, input voltages, and currents of the reactions were monitored with an

Aimin Huang; Guanguang Xia; Jinyun Wang; Steven L. Suib; Yuji Hayashi; Hiroshige Matsumoto

2000-01-01

430

Theoretical analysis of deposition and melting process during throttling high pressure CO 2 into atmosphere  

Microsoft Academic Search

Previous study has discovered that periodic solid CO2 deposition and melting phenomena happen during releasing high pressure CO2 through a safety valve from CO2 refrigeration system into atmosphere, and that a longer duration of the deposition and a shorter duration of melting are advantageous for the system safety. In order to know the suitable parameters to get a longer duration

Dong-ping Huang; Guo-liang Ding; Hans Quack

2007-01-01

431

Comparing Deposition Properties in an Atmospheric Pressure Plasma System Operating in Uniform and Nonuniform Modes  

Microsoft Academic Search

A large-scale atmospheric pressure plasma has been generated in helium, and the time-resolved optical and electrical properties have been shown to produce a homogeneous dielectric barrier discharge. Introducing tetraethyl orthosilicate as a liquid aerosol into this plasma produced clear, uniform, and smooth plasma polymerized coatings. Optical imaging studies have shown that adding 1% oxygen to the gas mixture induced a

Barry Twomey; Denis P. Dowling; Gerry Byrne; William G. Graham; Lucas F. Schaper; Damian Della Croce; Alan Hynes; Liam O'Neill

2009-01-01

432

Tthe study of black matrix ashing of FPD industry by atmospheric pressure plasma technology  

Microsoft Academic Search

Summary form only given. The black matrix (BM) rework using traditional wet process in the LCD industries is time consuming, costly and pollution. However, the plasma process provides a fast, less expensive and clean alternative. Especially, it is noticed that atmospheric pressure plasma attracts many attentions due to their lower equipment cost, operating without chambers and most suitable for large

Wen-Tzong Hsieh; Chen-Der Tsai; Je-Uai Lin; Chun-Hsien Su; Chi-Hung Liu

2009-01-01

433

Nylon 66, Nylon 46, and Pet Phase-Transfer-Catalyzed Alkaline Depolymerization at Atmospheric Pressure  

Microsoft Academic Search

The depolymerization of PET, nylon 66, and nylon 46 at high temperatures in an autoclave is well known in the patent literature. We sought to invent processes for the depolymerization of PET, nylon 66, and nylon 46 in alkaline solutions at low temperatures and atmospheric pressure. A method was developed for the depolymerization of polyethylene terephthalate (PET) which involved the

Malcolm B. Polk; Leighton L. Leboeuf; Munish Shah; Chee-Youb Won; Xiaodong Hu; Wen Ding

1999-01-01

434

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

SciTech Connect

Two large aperture, 10 cell atmospheric-pressure isobutane Cherenkov counters were designed and constructed for a SLAC streamer chamber experiment. The rejection efficiencies for a 9 GeV/c ..pi../sup -/ were measured to be 99.838 +- .006% and 99.717 +- 008% for the two counters. The design details and performance characteristics are discussed.

Hylen, J.; Ma, Z.M.; Jawahery, A.; Maruyama, T.; Milburn, R.; Thornton, R.

1980-05-24

435

On-Line Coating of Glass with Tin Oxide by Atmospheric Pressure Chemical Vapor Deposition.  

National Technical Information Service (NTIS)

Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The ...

A. H. McDaniel J. F. Sopko M. Allendorf M. Li W. G. Houf Y. Chae

2006-01-01

436

Optimization of an atmospheric pressure direct-contact DBD for the treatment of aqueous pharmaceutical solutions  

Microsoft Academic Search

Summary form only given. Ozone has been widely used in water treatment due to its extreme reactivity and its strong oxidizing properties. Technologies using electrical discharges generated directly over or in the fluid to be treated are being studied because they may prove to be cheap and effective. In this research project, a hybrid gas-liquid atmospheric pressure dielectric barrier discharge

J. Jureidini; S. Coulombe

2006-01-01

437

Freezing and ice crystals formed in a cylindrical food model: part I. Freezing at atmospheric pressure  

Microsoft Academic Search

Cylindrical gelatin gels were frozen at atmospheric pressure with different operating conditions (air-blast freezing at different air temperatures and brine freezing). A method to calculate a local freezing rate was proposed to take into account the variation of freezing rate as a function of the radius. A linear evolution of the local freezing rate according to the radius was observed

D Chevalier; A Le Bail; M Ghoul

2000-01-01

438

Surface modification of PET film by a DBD device at atmospheric pressure  

Microsoft Academic Search

Plasma treatments are used to modify surface properties of materials such as adhesivity, hydrophobicity, oleophobicity, hydrophilicity. The plasma interaction with the surface produces modifications of its chemical structure and morphology.The present work shows the surface modification of polyethylene terephthalate film (PET) after the exposure to an atmospheric pressure air dielectric barrier discharge (DBD).The treated surface has been analyzed using atomic

P. Esena; C. Riccardi; S. Zanini; M. Tontini; G. Poletti; F. Orsini

2005-01-01

439

Uniform glowlike plasma source assisted by preionization of spark in ambient air at atmospheric pressure  

SciTech Connect

The ultraviolet radiation produced by spark discharges is employed to supply preionization for the dielectric barrier discharge in ambient air at atmospheric pressure. The effect of ultraviolet preionization and overvoltage on improving the uniformity of the dielectric barrier discharge is investigated experimentally. Based on the emission spectra and voltage-current wave forms, the optical and electrical characteristics of the discharge are discussed.

Qi Bing; Ren Chunsheng; Wang Dezhen; Li Shouzhe; Wang Kun; Zhang Yutao [State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Department of Physics, Dalian University of Technology, Dalian 116023 (China)

2006-09-25

440

Dispersion of contaminant during oscillatory gas-motions driven by atmospheric pressure variations  

Microsoft Academic Search

Cyclical variations in atmospheric pressure cause vertical oscillatory motions of gases within the permeable earth. In an idealized homogeneous porous medium having uniform velocity at every elevation the induced motions would be piston-like and reversible, and would not contribute to the net vertical transport of radioactive gases. In any real geologic medium there are inonhomogeneities occurring on many different length

E. W. Peterson; K. Lie; R. H. Nilson

1987-01-01

441

Breakdown voltage measurements in alkali-metal-seeded rare gases at elevated temperatures and atmospheric pressure  

Microsoft Academic Search

The results of breakdown voltage measurements in various rare-gas - alkali-metal mixtures at atmospheric pressure and elevated temperature are given, the diluent gases being helium, neon and argon, and the seed metals, caesium, potassium and sodium. The breakdown voltage is shown to increase linearly as the electrode spacing rises from 1 to 15 mm, and to show little systematic variation

H. I. Ellington

1968-01-01

442

Two-dimensional numerical study of atmospheric pressure glows in helium with impurities  

Microsoft Academic Search

A two-dimensional numerical model of an atmospheric pressure glow (APG) discharge was developed. The simulation of the APG in helium with some nitrogen impurities successfully reproduced the discharge evolution during the breakdown process observed in experiments. The results show that the breakdown first appears at the central region of the discharge followed by the axial and radial propagation of the

P. Zhang; U. Kortshagen

2006-01-01

443

Temperature Analysis of Copper Wire in a Plasma Annealing System at Atmospheric Pressure  

Microsoft Academic Search

In this study, the temperature characteristic of the thin copper wire annealed in atmospheric pressure dielectric barrier discharge (APDBD) system is studied. An equivalent circuit model was used to analyze the wire surface temperature in APDBD. The analysis model showed that the ion bombardment on the wire surface was the main factor that determined wire surface temperature. The average temperature

Dam N. Tran; Vinh P. Nguyen; Toru Sasaki; Takashi Kikuchi; Nobuhiro Harada

2011-01-01

444

Control of polishing of diamond films using microactuation and an atmospheric pressure plasma  

Microsoft Academic Search

In this work, the diamond deposited by hot filament chemical vapor deposition (CVD) is polished using an atmospheric pressure plasma. In order to position the film relative to the plasma, a microactuator system is designed using a stack of domed piezoelectric actuators. A dynamic model based on the physical system is developed and the model parameters are measured experimentally. A

Matt S. Detrick; G. N. Washington; Vish V. Subramaniam

2003-01-01

445

Parametric effects on thin film growth and uniformity in an atmospheric pressure impinging jet CVD reactor  

Microsoft Academic Search

A systematic parametric study has been performed to study the effects of various geometrical parameters on the growth rate and growth rate uniformity in a jet impingement chemical vapor deposition reactor operated at atmospheric pressure. A previously validated two-dimensional axisymmetric computational model is used to numerically solve the equations governing variable density flow, and energy and species transport. Buoyancy-induced secondary

S. P. Vanka; G. Luo; N. G. Glumac

2004-01-01

446

Effects of low atmospheric pressure on combustion characteristics of polyethylene and polymethyl methacrylate  

Microsoft Academic Search

Combustion characteristics of polymers are affected significantly by low atmospheric pressure and oxygen concentration at high altitude. In this study, vertical downward experiments aimed at investigating these characteristics, including mass loss rate (burning rate), flame temperature, flame spread rate, and flame height for polyethylene and polymethyl methacrylate having different thicknesses were conducted at elevations of 2295 m (77.4 kPa) in

Junhui Gong; Lizhong Yang; Xiaodong Zhou; Zhihua Deng; Gao Lei; Wenjun Wang

2012-01-01

447

Direct-current glow discharges in atmospheric pressure air and nitrogen plasmas  

Microsoft Academic Search

Summary form only given. There is considerable interest in methods for efficiently producing large volumes of atmospheric pressure air plasmas at gas temperatures below 2000 K with free electron densities of 1013 cm-3. One approach consists in targeting the energy addition to the free electrons by application of electric fields. Investigations have been conducted to understand and validate the mechanisms

L. Yu; D. M. Packan; C. O. Laux; C. H. Kruger

2001-01-01

448

Deposition and analysis of thin films produced in atmospheric pressure glow discharge  

Microsoft Academic Search

The atmospheric pressure glow discharge was used for the deposition of thin organosilicon polymer films. The discharge was burning in pure nitrogen used as a carrier gas with a small admixture of organosilicon compound - hexamethyldisiloxane (HMDSO) which was used as a monomer. The temperature of the substrate was elevated up to 120 °C to obtain harder thin films. The

M. Šíra; D. Franta; D. Trunec

449

The Relationship of the MOLA Topography of Mars to the Mean Atmospheric Pressure  

Microsoft Academic Search

The MOLA topography of Mars is based on a new mean radius of the planet and new equipotential surface for the areoid. The mean atmospheric pressure surface of 6.1mbars that has been used in the past as a reference level for topography does not apply to the zero level of MOLA elevations. The MOLA mean radius of the planet is

D. E. Smith; M. T. Zuber

1999-01-01

450

Power consideration in the pulsed dielectric barrier discharge at atmospheric pressure  

Microsoft Academic Search

Nonequilibrium, atmospheric pressure discharges are rapidly becoming an important technological component in material processing applications. Amongst their attractive features is the ability to achieve enhanced gas phase chemistry without the need for elevated gas temperatures. To further enhance the plasma chemistry, pulsed operation with pulse widths in the nanoseconds range has been suggested. We report on a specially designed, dielectric

M. Laroussi; X. Lu; V. Kolobov; R. Arslanbekov

2004-01-01

451

Mechanism of Blood Coagulation by Non-Thermal Atmospheric Pressure Dielectric Barrier Discharge  

Microsoft Academic Search

Summary form only given. Blood coagulation by direct contact of nonthermal atmospheric pressure Dielectric Barrier Discharge (DBD) plasma in vitro has been reported previously. This discharge appears to promote rapid blood coagulation by enhancing natural coagulation processes. However, there is no detailed understanding of the specific mechanisms by which this nonthermal plasma coagulates blood. In this paper we investigate few

S. Kalghatgi; G. Fridman; M. Balasubramanian; A. Brooks; V. Vasilets; A. Fridman; A. Gutsol; G. Friedman

2007-01-01

452

An atmospheric-pressure microplasma jet source for the optical emission spectroscopic analysis of liquid sample  

Microsoft Academic Search

A miniaturized atmospheric-pressure thermal plasma jet source has been developed as a sensitive detector of a portable liquid analysis system that can fulfil various requirements of `on-site' analysis. The plasma source design required for achieving higher power transfer efficiency to the plasma has been studied mainly so that it can be operated with a commercially available compact VHF transmitter. The

Takanori Ichiki; Toru Koidesawa; Yasuhiro Horiike

2003-01-01

453

Flame Structure and Flame Reaction Kinetics. III. Measurement of Temperature Profiles in Flames at Atmospheric Pressure  

Microsoft Academic Search

The temperature profile m a slow burning, flat hydrogen-nitrogen-oxygen flame at atmospheric pressure has been measured by means of (1) a thermocouple probe which could be moved through the flame zone, and (2) an optical method which mvolves measurement of the deflexion of rays of light passing through the flame in a direction normal to the temperature and refractive index

G. Dixon-Lewis; G. L. Isles

1969-01-01

454

Use of atmospheric pressure plasma technology for durable hydrophilicity enhancement of polymeric substrates  

Microsoft Academic Search

Parallel plates dielectric barrier discharge (DBD) at atmospheric pressure has been investigated to modify and functionalize the surface of different polymer substrates, e.g. polyolefins, poly(ethylene terephtalate), polyamide, in order to enhance their hydrophilic properties. Surface properties have been altered to meet the requirements of specific applications by introducing the appropriate functionalities through the use of either acetic acid or ethyl

M. F. Dubreuil; E. M. Bongaers

2008-01-01