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1

Atmospheric pressure cold plasma as an antifungal therapy  

SciTech Connect

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

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

2011-01-10

2

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

3

Cold Atmospheric Pressure Plasmas Created by Resonance Laser Optical Pumping  

NASA Astrophysics Data System (ADS)

Large volume, diffuse, non-thermal plasmas are produced in flowing gases at atmospheric pressures. The plasma is excited by a system of two high power c.w. carbon monoxide gas lasers, directed co-axially into a flowing gas absorption cell. Typical cell gas mixtures are N_2/O_2/CO in ratios of 0.92/0.03/0.05. Plasmas are sustained in such mixtures to 1 atm. total pressure, with the gases are flowing at velocities of 10 cm/sec. With 20 W total laser power, a diffuse glow plasma of 20 cm length and 1 cm diameter is created in the gas. The energy distribution in the translational, rotational, and the three molecular vibrational modes is determined using a combination of Raman and Fourier Transform Infrared emission spectroscopy. Electron densities are determined by Thomson discharge probes, and are 10^11 cm-3. The plasma has huge energy content in the molecular vibrational modes. with average mode energies ranging from 0.5 to 5 ev per molecule. The translational/rotational mode temperature remains cold, with average values of 500 K. Such discharges are unconditionally stable, and appear to be scalable to very large volumes. The thermodynamics and molecular energy transfer processes in these systems will be presented in detail.

Adamovich, I. V.; Chidley, M.; Ploenjes, E.; Palm, P.; Rich, J. W.

1999-10-01

4

Cold atmospheric pressure air plasma jet for medical applications  

Microsoft Academic Search

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

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

2008-01-01

5

Atmospheric-pressure cold plasma jet for medical applications  

Microsoft Academic Search

An atmospheric-pressure plasma jet operated with air is presented. The plasma jet device is composed of a porous alumina dielectric element, an outer electrode, and a hollow inner electrode. Microdischarges in the porous alumina evolve to form a plasma jet that reaches lengths up to several tens of millimeters as the flow rate of the working gas increases. The discharge

Won-Seok Kang; Yong-Cheol Hong; Yoo-Beom Hong; Jae-Ho Kim; Han Sup Uhm

2010-01-01

6

Surface modification of polymer fibre by the new atmospheric pressure cold plasma jet  

Microsoft Academic Search

A new cold plasma jet has been developed for surface modification of materials at atmospheric pressure. This new cold plasma jet generator is composed of two concentric cylindrical all-metal tube electrodes. The argon is fed into the inner-grounded electrode, the outer electrode is connected to the high-voltage power supply and covered with a layer of dielectric, and then a stable

Cheng Cheng; Zhang Liye; Ru-Juan Zhan

2006-01-01

7

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

Microsoft Academic Search

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

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

2006-01-01

8

Cold arc-plasma jet under atmospheric pressure for surface modification  

Microsoft Academic Search

A relatively cold arc-plasma jet under atmospheric pressure was developed using a pulse power supply, called a Plasma Energized (PEN)-Jet. A needle electrode was placed in a glass tube, and a cap electrode with a center-hole (3 mm diameter) was placed at the tube end. The electric arc was discharged between the electrodes by applying intermittent bipolar pulse power. By

Jungo Toshifuji; Takashi Katsumata; Hirofumi Takikawa; Tateki Sakakibara; Ichiro Shimizu

2002-01-01

9

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

Microsoft Academic Search

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

D Breden; K Miki; L L Raja

2012-01-01

10

The influence of air on streamer propagation in atmospheric pressure cold plasma jets  

Microsoft Academic Search

The formation and propagation mechanisms of atmospheric-pressure cold plasma jets and the influence of air molecules including the nitrogen and the oxygen molecules on them are investigated by a one-dimensional fluid model in a needle-to-plane discharge in helium. It is shown that the air molecules have significant influence on the bullet velocity and the plasma jet length. As the air

Fucheng Liu; Dingzong Zhang; Dezhen Wang

11

Chemical modification of amino acids by atmospheric-pressure cold plasma in aqueous solution  

NASA Astrophysics Data System (ADS)

Plasma medicine is an attractive new research area, but the principles of plasma modification of biomolecules in aqueous solution remain elusive. In this study, we investigated the chemical effects of atmospheric-pressure cold plasma on 20 naturally occurring amino acids in aqueous solution. High-resolution mass spectrometry revealed that chemical modifications of 14 amino acids were observed after plasma treatment: (i) hydroxylation and nitration of aromatic rings in tyrosine, phenylalanine and tryptophan; (ii) sulfonation and disulfide linkage formation of thiol groups in cysteine; (iii) sulfoxidation of methionine and (iv) amidation and ring-opening of five-membered rings in histidine and proline. A competitive reaction experiment using 20 amino acids demonstrated that sulfur-containing and aromatic amino acids were preferentially decreased by the plasma treatment. These data provide fundamental information for elucidating the mechanism of protein inactivation for biomedical plasma applications.

Takai, Eisuke; Kitamura, Tsuyoshi; Kuwabara, Junpei; Ikawa, Satoshi; Yoshizawa, Shunsuke; Shiraki, Kentaro; Kawasaki, Hideya; Arakawa, Ryuichi; Kitano, Katsuhisa

2014-07-01

12

Cold atmospheric pressure plasma and decontamination. Can it contribute to preventing hospital-acquired infections?  

PubMed

Healthcare-associated infections (HCAIs) affect ?4.5 million patients in Europe alone annually. With the ever-increasing number of 'multi-resistant' micro-organisms, alternative and more effective methods of environmental decontamination are being sought as an important component of infection prevention and control. One of these is the use of cold atmospheric pressure plasma (CAPP) systems with clinical applications in healthcare facilities. CAPPs have been shown to demonstrate antimicrobial, antifungal and antiviral properties and have been adopted for other uses in clinical medicine over the past decade. CAPPs vary in their physical and chemical nature depending on the plasma-generating mechanism (e.g. plasma jet, dielectric barrier discharge, etc.). CAPP systems produce a 'cocktail' of species including positive and negative ions, reactive atoms and molecules (e.g. atomic oxygen, ozone, superoxide and oxides of nitrogen), intense electric fields, and ultraviolet radiation (UV). The effects of these ions have been studied on micro-organisms, skin, blood, and DNA; thus, a range of possible applications of CAPPs has been identified, including surface decontamination, wound healing, biofilm removal, and even cancer therapy. Here we evaluate plasma devices, their applications, mode of action and their potential role specifically in combating HCAIs on clinical surfaces. PMID:25146226

O'Connor, N; Cahill, O; Daniels, S; Galvin, S; Humphreys, H

2014-10-01

13

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

14

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

15

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

Microsoft Academic Search

In this letter, a room temperature atmospheric pressure plasma jet device is reported. The high voltage electrode of the device is covered by a quartz tube with one end closed. The device, which is driven by a kilohertz ac power supply, is capable of generating a plasma plume up to 11 cm long in the surrounding room air. The rotational

Xinpei Lu; Zhonghe Jiang; Qing Xiong; Zhiyuan Tang; Xiwei Hu; Yuan Pan

2008-01-01

16

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

17

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

18

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

19

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

SciTech Connect

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

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

2008-02-25

20

Inactivation of Staphylococcus aureus and Enterococcus faecalis by a direct-current, cold atmospheric-pressure air plasma microjet?  

PubMed Central

Objective A direct-current, cold atmospheric-pressure air plasma microjet (PMJ) was performed to inactivate Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. Methods In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum (OES) were used to understand the possible inactivation mechanisms of PMJ. Results The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. Conclusion The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances. PMID:23554639

Tian, Ye; Sun, Peng; Wu, Haiyan; Bai, Na; Wang, Ruixue; Zhu, Weidong; Zhang, Jue; Liu, Fuxiang

2010-01-01

21

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

PubMed

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

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

2013-12-01

22

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

23

An atmospheric-pressure, high-aspect-ratio, cold micro-plasma  

PubMed Central

An atmospheric pressure nonequilibrium Ar micro-plasma generated inside a micro-tube with plasma radius of 3??m and length of 2.7?cm is reported. The electron density of the plasma plume estimated from the broadening of the Ar emission line reaches as high as 3 × 1016?cm?3. The electron temperature obtained from CR model is 1.5?ev while the gas temperature of the plasma estimated from the N2 rotational spectrum is close to room temperature. The sheath thickness of the plasma could be close to the radius of the plasma. The ignition voltages of the plasma increase one order when the radius of the dielectric tube is decreased from 1?mm to 3??m. PMID:25502006

Lu, X.; Wu, S.; Gou, J.; Pan, Y.

2014-01-01

24

An atmospheric-pressure, high-aspect-ratio, cold micro-plasma  

NASA Astrophysics Data System (ADS)

An atmospheric pressure nonequilibrium Ar micro-plasma generated inside a micro-tube with plasma radius of 3 ?m and length of 2.7 cm is reported. The electron density of the plasma plume estimated from the broadening of the Ar emission line reaches as high as 3 × 1016 cm-3. The electron temperature obtained from CR model is 1.5 ev while the gas temperature of the plasma estimated from the N2 rotational spectrum is close to room temperature. The sheath thickness of the plasma could be close to the radius of the plasma. The ignition voltages of the plasma increase one order when the radius of the dielectric tube is decreased from 1 mm to 3 ?m.

Lu, X.; Wu, S.; Gou, J.; Pan, Y.

2014-12-01

25

An atmospheric-pressure, high-aspect-ratio, cold micro-plasma.  

PubMed

An atmospheric pressure nonequilibrium Ar micro-plasma generated inside a micro-tube with plasma radius of 3??m and length of 2.7?cm is reported. The electron density of the plasma plume estimated from the broadening of the Ar emission line reaches as high as 3 × 10(16)?cm(-3). The electron temperature obtained from CR model is 1.5?ev while the gas temperature of the plasma estimated from the N2 rotational spectrum is close to room temperature. The sheath thickness of the plasma could be close to the radius of the plasma. The ignition voltages of the plasma increase one order when the radius of the dielectric tube is decreased from 1?mm to 3??m. PMID:25502006

Lu, X; Wu, S; Gou, J; Pan, Y

2014-01-01

26

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

SciTech Connect

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

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

2011-06-15

27

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

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

28

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

29

High-Density Polyethylene (HDPE) Surface Treatment Using an RF Capacitive Atmospheric Pressure Cold Ar Plasma Jet  

NASA Astrophysics Data System (ADS)

In this study, a high-density polyethylene (HDPE, 5-mm-thick, 0.95 g/cm3) surface was treated using an RF capacitive atmospheric pressure cold Ar plasma jet. By using this Ar plasma jet, a hydrophilic HDPE surface was formed during the plasma treatment. In particular, the effects of an additive gas (N2 or O2) on the HDPE surface treatment were investigated in detail. It was shown that the addition of N2 or O2 gas had an important influence on the HDPE surface treatment. Compared to pure Ar plasma treatment, a lower value of water contact angle (WCA) was obtained when a trace of N2 or O2 gas was added. It was also found that besides the quantities of active species in the plasma jet, the treatment temperature played an important role in the HDPE surface treatment. This is because surface molecular motion is not negligible when the treatment temperature is close to the melting point of the polymer.

Fei, Xiaomeng; Shin-ichi, Kuroda; Tamio, Mori; Katsuhiko, Hosoi

2013-06-01

30

MS2 Virus Inactivation by Atmospheric-Pressure Cold Plasma Using Different Gas Carriers and Power Levels.  

PubMed

In this study, airborne MS2 bacteriophages were exposed for subsecond time intervals to atmospheric-pressure cold plasma (APCP) produced using different power levels (20, 24, and 28 W) and gas carriers (ambient air, Ar-O2 [2%, vol/vol], and He-O2 [2%, vol/vol]). In addition, waterborne MS2 viruses were directly subjected to the APCP treatment for up to 3 min. MS2 viruses with and without the APCP exposure were examined by scanning electron microscopy (SEM), reverse transcription-PCR (RT-PCR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Viral inactivation was shown to exhibit linear relationships with the APCP generation power and exposure time (R(2) > 0.95 for all energy levels tested) up to 95% inactivation (1.3-log reduction) after a subsecond airborne exposure at 28 W; about the same inactivation level was achieved for waterborne viruses with an exposure time of less than 1 min. A larger amount of reactive oxygen species (ROS), such as atomic oxygen, in APCP was detected for a higher generation power with Ar-O2 and He-O2 gas carriers. SEM images, SDS-PAGE, and agarose gel analysis of exposed waterborne viruses showed various levels of damage to both surface proteins and their related RNA genes after the APCP exposure, thus leading to the loss of their viability and infectivity. PMID:25416775

Wu, Yan; Liang, Yongdong; Wei, Kai; Li, Wei; Yao, Maosheng; Zhang, Jue; Grinshpun, Sergey A

2015-02-01

31

A dominant role of oxygen additive on cold atmospheric-pressure He + O{sub 2} plasmas  

SciTech Connect

We present in this paper how oxygen additive impacts on the cold atmospheric-pressure helium plasmas by means of a one-dimensional fluid model. For the oxygen concentration [O{sub 2}]?>??0.1%, the influence of oxygen on the electron characteristics and the power dissipation becomes important, e.g., the electron density, the electron temperature in sheath, the electron-coupling power, and the sheath width decreasing by 1.6 to 16 folds with a two-log increase in [O{sub 2}] from 0.1% to 10%. Also the discharge mode evolves from the ? mode to the ? mode. The reactive oxygen species are found to peak in the narrow range of [O{sub 2}]?=?0.4%–0.9% in the plasmas, similar to their power-coupling values. This applies to their wall fluxes except for those of O* and O{sub 2}{sup ?}. These two species have very short lifetimes, thus only when generated in boundary layers within several micrometers next to the electrode can contribute to the fluxes. The dominant reactive oxygen species and the corresponding main reactions are schematically presented, and their relations are quantified for selected applications.

Yang, Aijun; Liu, Dingxin, E-mail: liudingxin@gmail.com, E-mail: xhw@mail.xjtu.edu.cn; Rong, Mingzhe; Wang, Xiaohua, E-mail: liudingxin@gmail.com, E-mail: xhw@mail.xjtu.edu.cn [Centre for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China); Kong, Michael G. [Centre for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China); Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

2014-08-15

32

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

PubMed

The application of cold atmospheric pressure plasma for decontamination of a sliced ready-to-eat (RTE) meat product (bresaola) inoculated with Listeria innocua was investigated. Inoculated samples were treated at 15.5, 31, and 62 W for 2-60 s inside sealed linear-low-density-polyethylene bags containing 30% oxygen and 70% argon. Treatments resulted in a reduction of L. innocua ranging from 0.8 ± 0.4 to 1.6 ± 0.5 log cfu/g with no significant effects of time and intensity while multiple treatments at 15.5 and 62 W of 20 s with a 10 min interval increased reduction of L. innocua with increasing number of treatments. Concentrations of thiobarbituric acid reactive substances (TBARS) increased with power, treatments and storage time and were significantly higher than those of control samples after 1 and 14 days of storage at 5 °C. However, the levels were low (from 0.1 to 0.4 mg/kg) and beneath the sensory threshold level. Surface colour changes included loss of redness of ?40% and 70% after 1 and 14 days of storage, respectively, regardless of plasma treatment. The results indicate that plasma may be applicable in surface decontamination of pre-packed RTE food products. However, oxidation may constitute an issue in some products. PMID:22265306

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

2012-05-01

33

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

34

MS2 Virus Inactivation by Atmospheric-Pressure Cold Plasma Using Different Gas Carriers and Power Levels  

PubMed Central

In this study, airborne MS2 bacteriophages were exposed for subsecond time intervals to atmospheric-pressure cold plasma (APCP) produced using different power levels (20, 24, and 28 W) and gas carriers (ambient air, Ar-O2 [2%, vol/vol], and He-O2 [2%, vol/vol]). In addition, waterborne MS2 viruses were directly subjected to the APCP treatment for up to 3 min. MS2 viruses with and without the APCP exposure were examined by scanning electron microscopy (SEM), reverse transcription-PCR (RT-PCR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Viral inactivation was shown to exhibit linear relationships with the APCP generation power and exposure time (R2 > 0.95 for all energy levels tested) up to 95% inactivation (1.3-log reduction) after a subsecond airborne exposure at 28 W; about the same inactivation level was achieved for waterborne viruses with an exposure time of less than 1 min. A larger amount of reactive oxygen species (ROS), such as atomic oxygen, in APCP was detected for a higher generation power with Ar-O2 and He-O2 gas carriers. SEM images, SDS-PAGE, and agarose gel analysis of exposed waterborne viruses showed various levels of damage to both surface proteins and their related RNA genes after the APCP exposure, thus leading to the loss of their viability and infectivity. PMID:25416775

Wu, Yan; Liang, Yongdong; Wei, Kai; Li, Wei; Grinshpun, Sergey A.

2014-01-01

35

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. PMID:23967387

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

2013-01-01

36

Absolute atomic oxygen and nitrogen densities in radio-frequency driven atmospheric pressure cold plasmas: Synchrotron vacuum ultra-violet high-resolution Fourier-transform absorption measurements  

SciTech Connect

Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, in particular, in plasma medicine. Absolute densities of atomic oxygen and atomic nitrogen were measured in a radio-frequency driven non-equilibrium plasma operated at atmospheric pressure using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Measurements were carried out in plasmas operated in helium with air-like N{sub 2}/O{sub 2} (4:1) admixtures. A maximum in the O-atom concentration of (9.1 {+-} 0.7) Multiplication-Sign 10{sup 20} m{sup -3} was found at admixtures of 0.35 vol. %, while the N-atom concentration exhibits a maximum of (5.7 {+-} 0.4) Multiplication-Sign 10{sup 19} m{sup -3} at 0.1 vol. %.

Niemi, K.; O'Connell, D.; Gans, T. [York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom); Oliveira, N. de; Joyeux, D.; Nahon, L. [Synchrotron Soleil, l'Orme des Merisiers, St. Aubin BP 48, 91192 Gif sur Yvette Cedex (France); Booth, J. P. [Laboratoire de Physique des Plasmas-CNRS, Ecole Polytechnique, 91128 Palaiseau (France)

2013-07-15

37

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

38

2009-2010 Cold Season National Oceanic and Atmospheric Administration  

E-print Network

Midwest and New England. High amplitude flow patterns helped the cold arctic air remain entrenched) is a periodic fluctuation in sea surface temperature (El Niño) and the air pressure of the overlying atmosphere

39

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

NASA Astrophysics Data System (ADS)

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

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

40

Pluto's Increasing Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

In 2007, the occultation of a V=13.2 magnitude star was successfully observed from Mt. John Observatory, Mt. Canopus Observatory and our 14-inch Meade portable system in Musselroe Bay, New Zealand. We simultaneously fit an isothermal model atmosphere (Eliot and Young, 1992) to the main drop and recovery of the observed occultation light curves to derive global atmospheric parameters and a geometric solution. The data is well fit by a spherical atmospheric model with no need to fit for an oblate profile. The isothermal atmospheric solution gives a temperature of 112 ± 1 K and a pressure of 2.4 ± 0.1 microbar at a radius of 1275 km. This is an increase in temperature of 8 K and a 28% increase in pressure at our reference radius over 13 months (the previous stellar occultation was in June 2006, Young et al. 2008) with no significant change in half-light radius. Due to the increase in temperature and hence scale height, we expect the surface pressure did not increase as dramatically. The sensitivity of atmospheric pressure to changes in isothermal temperature will be discussed. This work was supported by NASA planetary astronomy grant NNG05GF05G and NSF major research instrumentation grant AST0321338.

Olkin, Catherine B.; Young, L.; Young, E.; Buie, M.; French, R.; Howell, R.; Regester, J.; Ruhland, C.

2009-09-01

41

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

42

Cold pressure welded copper-constantan thermocouples  

Microsoft Academic Search

Cold pressure welding has been used to produce a lap junction between 0.15 mm thick strips of copper and constantan which had been plated with 2 mu m of nickel. The junction thickness after welding was 0.10 mm, and after further cold rolling to 0.06 mm a thermocouple performance within the requirements of BS 1041 (1966) was obtained.

R. Vipond

1975-01-01

43

Microwave Atmospheric-Pressure Sensor  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

44

Desorption atmospheric pressure photoionization.  

PubMed

An ambient ionization technique for mass spectrometry, desorption atmospheric pressure photoionization (DAPPI), is presented, and its application to the rapid analysis of compounds of various polarities on surfaces is demonstrated. The DAPPI technique relies on a heated nebulizer microchip delivering a heated jet of vaporized solvent, e.g., toluene, and a photoionization lamp emitting 10-eV photons. The solvent jet is directed toward sample spots on a surface, causing the desorption of analytes from the surface. The photons emitted by the lamp ionize the analytes, which are then directed into the mass spectrometer. The limits of detection obtained with DAPPI were in the range of 56-670 fmol. Also, the direct analysis of pharmaceuticals from a tablet surface was successfully demonstrated. A comparison of the performance of DAPPI with that of the popular desorption electrospray ionization method was done with four standard compounds. DAPPI was shown to be equally or more sensitive especially in the case of less polar analytes. PMID:17803282

Haapala, Markus; Pól, Jaroslav; Saarela, Ville; Arvola, Ville; Kotiaho, Tapio; Ketola, Raimo A; Franssila, Sami; Kauppila, Tiina J; Kostiainen, Risto

2007-10-15

45

Cold atmospheric plasma in cancer therapy  

SciTech Connect

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

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

2013-05-15

46

Atmospheric Pressure Indicator.  

ERIC Educational Resources Information Center

Discusses observable phenomena related to air pressure. Describes a simple, unobtrusive, semiquantitative device to monitor the changes in air pressure that are associated with altitude, using a soft-drink bottle and a balloon. (JRH)

Salzsieder, John C.

1995-01-01

47

Pluto's Increasing Atmospheric Pressure  

Microsoft Academic Search

In 2007, the occultation of a V=13.2 magnitude star was successfully observed from Mt. John Observatory, Mt. Canopus Observatory and our 14-inch Meade portable system in Musselroe Bay, New Zealand. We simultaneously fit an isothermal model atmosphere (Eliot and Young, 1992) to the main drop and recovery of the observed occultation light curves to derive global atmospheric parameters and a

Catherine B. Olkin; L. Young; E. Young; M. Buie; R. Howell; J. Regester; C. Ruhland

2009-01-01

48

Constraints on Early Mars atmospheric pressure  

E-print Network

Constraints on Early Mars atmospheric pressure from small ancient craters impactors, so impact crater size is a probe of atmospheric pressure. ebar4bar Diameter (m) Fractionofcraterssmallerthan ! Atmospheric pressure upper limit

Kite, Edwin

49

An atmospheric pressure plasma source  

Microsoft Academic Search

An atmospheric pressure plasma source operated by radio frequency power has been developed. This source produces a unique discharge that is volumetric and homogeneous at atmospheric pressure with a gas temperature below 300 °C. It also produces a large quantity of oxygen atoms, ~5×1015 cm-3, which has important value for materials applications. A theoretical model shows electron densities of 0.2-2×1011

Jaeyoung Park; I. Henins; H. W. Herrmann; G. S. Selwyn; J. Y. Jeong; R. F. Hicks; D. Shim; C. S. Chang

2000-01-01

50

Atmospheric Pressure During Landing  

NASA Technical Reports Server (NTRS)

This figure shows the variation with time of pressure (dots) measured by the Pathfinder MET instrument during the landing period shown in image PIA00797. The two diamonds indicate the times of bridal cutting and 1st impact. The overall trend in the data is of pressure increasing with time. This is almost certainly due to the lander rolling downhill by roughly 10 m. The spacing of the horizontal dotted lines indicates the pressure change expected from 10 m changes in altitude. Bounces may also be visible in the data.

1997-01-01

51

Temperature and pressure measurements at cold exit of counter-flow vortex tube with flow visualization of reversed flow  

NASA Astrophysics Data System (ADS)

In order to clarify the structure of the cold flow discharged from the counter-flow vortex tube (VT), the temperature and pressure of the cold flow were measured, and the existence and behavior of the reversed flow at the cold exit was studied using a simple flow visualization technique consisting of a 0.75mm-diameter needle, and an oil paint droplet. It is observed through this experiment that the Pitot pressure at the cold exit center can either be lower or higher than atmospheric pressure, depending on the inlet pressure and the cold fraction, and that a reversed flow is observed when the Pitot pressure at the cold exit center is lower than atmospheric pressure. In addition, it is observed that when reducing the cold fraction from unity at any arbitrary inlet pressure, the region of reversed and colder flow in the central part of cold exit extends in the downstream direction.

Yusof, Mohd Hazwan bin; Katanoda, Hiroshi; Morita, Hiromitsu

2015-02-01

52

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

53

Air plasma jet with hollow electrodes at atmospheric pressure  

Microsoft Academic Search

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

Yong Cheol Hong; Han Sup Uhm

2007-01-01

54

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

55

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

56

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

57

Atmospheric-pressure plasma jet  

DOEpatents

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

Selwyn, Gary S. (Los Alamos, NM)

1999-01-01

58

Atmospheric-pressure guided streamers for liposomal membrane disruption  

SciTech Connect

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

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

2012-12-24

59

A Parametric Study of a Cold Atmospheric Plasma Jet  

Microsoft Academic Search

Summary form only given. Cold atmospheric plasma jets have shown considerable promise for many industrial and medical applications. However, their fundamental studies are much behind. In this contribution, we present a preliminary study of a cold atmospheric plasma jet struck inside a ceramic tube and ejected into its surrounding ambient air. Both helium and argon are used as the working

J. Z. Cao; D. W. Liu; J. L. Walsh; J. J. Shi; M. G. Kong

2007-01-01

60

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

61

Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma jet  

E-print Network

Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma March 2014) Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises possibilities of plasma sources under investigation, the non-equilibrium atmospheric pressure plasma jet (APPJ

Zexian, Cao

62

Atmospheric pressure plasmas: A review  

Microsoft Academic Search

This article attempts to give an overview of atmospheric plasma sources and their applications. The aim is to introduce, in a first part, the main scientific background concerning plasmas as well as the different atmospheric plasma sources (description, working principle). The second part focuses on the various applications of the atmospheric plasma technologies, mainly in the field of surface treatments.Thus

Claire Tendero; Christelle Tixier; Pascal Tristant; Jean Desmaison; Philippe Leprince

2006-01-01

63

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

64

CHAPTER 2. ATMOSPHERIC PRESSURE 2.1 MEASURING ATMOSPHERIC PRESSURE  

E-print Network

barometer, consisting of a long glass tube full of mercury inverted over a pool of mercury: Figure 2-1 Mercury barometer When the tube is inverted over the pool, mercury flows out of the tube, creating is the weight exerted by the overhead atmosphere on a unit area of surface. It can be measured with a mercury

Jacob, Daniel J.

65

Study of atmospheric pressure glow discharge  

Microsoft Academic Search

Summary form only given. Atmospheric pressure glow discharges (APGD) in gases such as Helium, Argon and air were studied. APGD in Helium between two parallel plane electrodes covered with dielectric plates was simulated on the basis of one-dimensional fluid model and the parameters' distributions along the discharge channel were obtained. The development of an electron avalanche in one atmosphere air

Mingze Lu; Xinxin Wang; Yikang Pu; Zhicheng Guan

2002-01-01

66

Shuttle Orbiter Atmospheric Revitalization Pressure Control Subsystem  

NASA Technical Reports Server (NTRS)

The Atmospheric Revitalization Pressure Control Subsystem (ARPCS) provides oxygen partial pressure and total pressure control for the habitable atmosphere of the Shuttle for either a one atmosphere environment or an emergency 8 PSIA mode. It consists of a Supply Panel, Control Panel, Cabin Pressure Relief Valves and Electronic Controllers. The panels control and monitor the oxygen and nitrogen supplies. The cabin pressure relief valves protect the habitable environment from overpressurization. Electronic controllers provide proper mixing of the two gases. This paper describes the ARPCS, addresses the changes in hardware that have occurred since the inception of the program; the performance of this subsystem during STS-1 and STS-2; and discusses future operation modes.

Walleshauser, J. J.; Ord, G. R.; Prince, R. N.

1982-01-01

67

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

NASA Astrophysics Data System (ADS)

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

Allen, Michael J.; Lee, Cameron C.

2014-11-01

68

[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

69

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

70

Pressure Field Study of the Tevatron Cold Compressors  

SciTech Connect

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

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

2004-06-23

71

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

72

Pressure Field Study of the Tevatron Cold Compressors  

NASA Astrophysics Data System (ADS)

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

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

2004-06-01

73

April 2007 Cold Wave National Oceanic and Atmospheric Administration  

E-print Network

The April 2007 Cold Wave occurred across much of the central Plains, Midwest and into the Southeast during of the event in concert with crop emergence and tree blooms. Winter wheat across the central Plains and Midwest through the Mississippi Valley and into the Southeast. A dominant ridge of high pressure, entrenched

74

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

75

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

76

MY NASA DATA: Atmospheric Pressure vs. Elevation  

NSDL National Science Digital Library

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

77

Apparatus for Cold, Pressurized Biogeochemical Experiments  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

78

Hot, cold, and annual reference atmospheres for Edwards Air Force Base, California (1975 version)  

NASA Technical Reports Server (NTRS)

Reference atmospheres pertaining to summer (hot), winter (cold), and mean annual conditions for Edwards Air Force Base, California, are presented from surface to 90 km altitude (700 km for the annual model). Computed values of pressure, kinetic temperature, virtual temperature, and density and relative differences percentage departure from the Edwards reference atmospheres, 1975 (ERA-75) of the atmospheric parameters versus altitude are tabulated in 250 m increments. Hydrostatic and gas law equations were used in conjunction with radiosonde and rocketsonde thermodynamic data in determining the vertical structure of these atmospheric models. The thermodynamic parameters were all subjected to a fifth degree least-squares curve-fit procedure, and the resulting coefficients were incorporated into Univac 1108 computer subroutines so that any quantity may be recomputed at any desired altitude using these subroutines.

Johnson, D. L.

1975-01-01

79

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

80

Sources of nonequilibrium plasma at atmospheric pressure  

Microsoft Academic Search

The electrical arc discharge in a transverse blowing gas flow [transverse arc - (TA)] and the discharge in the gas flows immersed into the liquid [discharge in the gas channel with a liquid wall - (DGCLW)] are studied as the sources of nonequilibrium plasma at the atmospheric pressure. Diagnostics of both discharges is made by optical emission spectroscopy. The population

I. Prysyazhnevych; V. Chernyak; J. D. Skalný; S. Matej?ik; V. Yukhymenko; S. Olszewsky; V. Naumov

2008-01-01

81

Atmospheric pressure at the time of dinosaurs  

Microsoft Academic Search

From bioenergetics, fluid mechanics and aerodynamics, we show that if the atmospheric pressure was higher at the time of the dinosaurs than it is today, we would be able to resolve a number of anomalies which puzzle scientists today. These concern how a giant pterosaur (quetzalcoatlus, with a 12-15 m wingspan) had enough power to fly; also, how a giant

Octave Levenspiel

2006-01-01

82

Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry  

E-print Network

Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry Anu Vaikkinen ablation atmo- spheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 e

Vertes, Akos

83

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

84

Protein destruction by atmospheric pressure glow discharges  

NASA Astrophysics Data System (ADS)

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.

2007-01-01

85

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

86

Atmospheric cold plasma jet for plant disease treatment  

NASA Astrophysics Data System (ADS)

This study shows that the atmospheric cold plasma jet is capable of curing the fungus-infected plant leaves and controlling the spread of infection as an attractive tool for plant disease management. The healing effect was significantly dependent on the size of the black spots infected with fungal cells and the leaf age. The leaves with the diameter of black spots of <2 mm can completely recover from the fungus-infected state. The plasma-generated species passing through the microns-sized stomas in a leaf can weaken the function of the oil vacuoles and cell membrane of fungal cells, resulting in plasma-induced inactivation.

Zhang, Xianhui; Liu, Dongping; Zhou, Renwu; Song, Ying; Sun, Yue; Zhang, Qi; Niu, Jinhai; Fan, Hongyu; Yang, Si-ze

2014-01-01

87

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

NASA Astrophysics Data System (ADS)

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

Hori, M. E.; Inoue, J.

2011-12-01

88

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

89

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

90

Martian Atmospheric Pressure Static Charge Elimination Tool  

NASA Technical Reports Server (NTRS)

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

Johansen, Michael R.

2014-01-01

91

[Spectral investigation of atmospheric pressure plasma column].  

PubMed

Atmospheric pressure plasma column has many important applications in plasma stealth for aircraft. In the present paper, a plasma column with a length of 65 cm was generated in argon at atmospheric pressure by using dielectric barrier discharge device with water electrodes in coaxial configurations. The discharge mechanism of the plasma column was studied by optical method and the result indicates that a moving layer of light emission propagates in the upstream region. The propagation velocity of the plasma bullet is about 0.6 x 10(5) m x s(-1) through optical measurement. Spectral intensity ratios as functions of the applied voltage and driving frequency were also investigated by spectroscopic method. The variation in spectral intensity ratio implies a change in the averaged electron energy. Results show that the averaged electron energy increases with the increase in the applied voltage and the driving frequency. These results have significant values for industrial applications of the atmospheric pressure discharge and have extensive application potentials in stealth for military aircraft. PMID:23016319

Li, Xue-Chen; Chang, Yuan-Yuan; Xu, Long-Fei

2012-07-01

92

Special issue: diagnostics of atmospheric pressure microplasmas  

NASA Astrophysics Data System (ADS)

In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of, e.g. Werner von Siemens [9], who studied a dielectric barrier discharge (DBD) in the context of ozone generation. DBD discharges often consist of numerous filamentary discharges which are inherently transient in nature and with a characteristic size similar to the dimensions of microplasmas. Several groups are investigating the stabilization of such plasma filaments to perform temporal and spatial resolved diagnostics. To this end and due to the many similar challenges for diagnostics, this type of discharge is also included in this special issue. Research on microplasmas is performed in many groups spread all over the world, and a biannual workshop is devoted to the topic. The 7th edition of this International Workshop on Microplasmas was held in Beijing in May 2013. Large research programs consisting of clusters of research labs such as in Japan, Germany, France and the USA have been producing a wealth of information available in the literature. As the editors of this special issue, we are very pleased to have attracted a collection of excellent papers from leading experts in the field covering most of the current diagnostics performed in microplasmas. As an introduction to the regular special issue papers, a review paper is included [10]. It describes the key characteristics of atmospheric pressure plasmas and microplasmas in particular, and reviews the state of the art in plasma diagnostics. Special attention has been given in this review to highlighting the issues and challenges to probe microplasmas. The regular papers cover a large range of different diagnostics including coherent anti-Stokes Raman scattering (CARS) [11], (two-photon) laser induced fluorescence ((Ta)LIF) [12, 13, 18, 24], absorption spectroscopy [13-18], optical emission spectroscopy [12, 16-21, 24], imaging [22, 23], surface diagnostics [24, 25] and mass spectrometry [26, 27]. Different aspects of microplasmas are broadly investigated from a perspective of diagnostics, modelling and applications. Diagnostics are pivotal to both the development of models and the optimization and explorat

Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

2013-11-01

93

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

94

Formation Mechanism of Atmospheric Pressure Plasma Jet  

E-print Network

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 to the tube orifice, both downstream and upstream simultaneously, and at a significantly reduced voltage. These results will help understand the underlying physics and facilitate a safer and more flexible implementation of this marvelous plasma source.

Jiang, Nan; Cao, Zexian

2008-01-01

95

Targeting the cancer cell cycle by cold atmospheric plasma  

NASA Astrophysics Data System (ADS)

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.

2012-09-01

96

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

NASA Technical Reports Server (NTRS)

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

Nesman, Tomas E.

2001-01-01

97

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

98

Pressure Drag of Obstacles in the Atmospheric Boundary Layer  

Microsoft Academic Search

Pressure drag of obstacles in the atmospheric boundary layer is computed with a mesoscale numerical model of the troposphere. Different parts of the drag can be separated from the numerical results: total pressure drag is determined from the surface pressure distribution, hydrostatic drag from the temperature distribution in the atmosphere, and form drag as a residual. The dependence of the

Stefan Emeis

1990-01-01

99

Quality characteristics of the radish grown under reduced atmospheric pressure  

Microsoft Academic Search

This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and

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

2008-01-01

100

Surface modification of polymeric materials by cold atmospheric plasma jet  

NASA Astrophysics Data System (ADS)

In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source - the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40° in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure.

Kostov, K. G.; Nishime, T. M. C.; Castro, A. H. R.; Toth, A.; Hein, L. R. O.

2014-09-01

101

Stability Measurements of an Atmospheric Pressure Arc  

NASA Astrophysics Data System (ADS)

Experiments on the stability of atmospheric pressure arcs have been started at PPPL to understand and improve the performance of arc furnaces used for processing applications in metallurgy and hazardous waste treatment. Previous studies have suggested that the violent instabilities in such arcs may be due to kink modes (P. M. Bellan and J. W. Higley. IEEE Trans. Plasma Sci., 20:1026-1035, Dec. 1992.) ^, (Ben Bowman. Properties of arcs in DC furnaces. Electric Furnace Conference Proceedings, pages 111-120, 1994). A 30 kW, 500 Amp CW DC experimental arc furnace was constructed with a graphite cathode and a molten steel anode. The arc plasma is diagnosed with high-speed optical detectors, Hall probes, and voltage and current monitors. Preliminary results show an intermittent helical instability at ? 1 kHz along with lower frequency turbulence. Fluctuation data under various operating conditions will be presented.

Karasik, Max; Lemunyan, G.; Roquemore, L.; Zweben, S. J.; Wurden, G. A.

1996-11-01

102

Measurement of Atmospheric Pressure Arc Jet Velocity  

NASA Astrophysics Data System (ADS)

A plasma arc jet originates at the cathode of a DC atmospheric pressure arc due to magnetic pumping(P.M. Bellan. Phys. Rev. Lett. 69, 3515 (1992).). This jet velocity can affect the equilibrium and stability of the arcs in electric arc furnaces used for steel recycling. Previous techniques to measure the arc jet speed included deflection of small pellets(B. Bowman. J. Phys. D: Appl. Phys. 5, 1422 (1972)) and Doppler-shifted plasma scattering(M. Irie et al. J. Phys. D: Appl. Phys. 10, 1599 (1977)). This poster will describe measurements of the arc jet velocity in the 200 Amp PPPL arc furnace, and compare these measurements with arc jet models.

May, Erick; Karasik, M.; Zweben, S. J.

1997-11-01

103

THE REMARKABLE HIGH PRESSURE OF THE LOCAL LEO COLD CLOUD  

SciTech Connect

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

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

2012-06-20

104

A global mechanism creating low atmospheric luminous cold plasmas  

NASA Astrophysics Data System (ADS)

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

Gitle Hauge, Bjørn; Petter Strand, Erling

2014-05-01

105

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

106

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

PubMed

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

Horie, Seichi

2014-02-01

107

Io meteorology - How atmospheric pressure is controlled locally by volcanos and surface frosts  

NASA Technical Reports Server (NTRS)

The present modification of the Ingersoll et al. (1985) hydrodynamic model of the SO2 gas sublimation-driven flow from the day to the night side of Io includes the effects of nonuniform surface properties noted in observational studies. Calculations are conducted for atmospheric pressures, horizontal winds, sublimation rates, and condensation rates for such surface conditions as patchy and continuous frost cover, volcanic venting, surface temperature discontinuities, subsurface cold trapping, and the propagation of insolation into the frost. While pressure is found to follow local vapor pressure away from the plumes, it becomes higher inside them.

Ingersoll, Andrew P.

1989-01-01

108

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

SciTech Connect

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

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

2009-08-24

109

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

110

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

111

Experimental investigation of atmospheric pressure nonequilibrium plasma chemistry  

Microsoft Academic Search

Atmospheric pressure plasmas are frequently considered to be in local thermodynamic equilibrium due to the high frequency of collisional processes which drive the plasma state toward a Maxwell-Boltzmann equilibrium. However, various forms of thermodynamic, ionizational, and chemical nonequilibrium have been demonstrated and investigated in atmospheric pressure plasma environments over the last several years, and the nonequilibrium behaviour of such systems

Charles H. Kruger; Thomas G. Owano; Christophe O. Laux

1997-01-01

112

Effects of cold atmospheric plasma on mucosal tissue culture  

NASA Astrophysics Data System (ADS)

Thermal plasmas have been commonly used in medical applications such as plasma ablation and blood coagulation. Newer developments show that plasmas can be generated with ion temperatures close to room temperature: these non-thermal or so-called cold atmospheric plasmas (CAPs) therefore open up a wide range of further biomedical applications. Based on the understanding of the bactericidal, virucidal and fungicidal properties of CAPs, information about the effects of CAP on mucosal cells and tissue is still lacking. Therefore this study focuses on the interaction of CAP with healthy head and neck mucosal cells on a molecular level. To analyse this interaction in detail, fresh tissue samples from healthy nasal and pharyngeal mucosa were harvested during surgery, assembled to a three-dimensional tissue culture model (mini organ cultures) and treated with CAP for different treatment times. Effects on the viability, necrosis induction and mutagenic activity were evaluated with the trypan blue exclusion test, Annexin-V/PI staining and alkaline microgel electrophoresis (comet assay). Trypan blue exclusion test revealed that the CAP treatment significantly decreases the cell viability for all tested treatment times (5, 10, 30, 60 and 120 s p < 0.05), but only a treatment time of 120 s showed a cytotoxic effect as the viability dropped below 90%. Annexin-V/PI staining revealed a significant increase in necrosis in CAP treated pharyngeal tissue cultures for treatment times of 60 and 120 s (p < 0.05). For nasal tissue this effect was already detected for a 30 s treatment (p < 0.05). Comet assay analysis showed no mutagenic effects after exposure to CAP.

Welz, Christian; Becker, Sven; Li, Yang-Fang; Shimizu, Tetsuji; Jeon, Jin; Schwenk-Zieger, Sabina; Thomas, Hubertus M.; Isbary, Georg; Morfill, Gregor E.; Harréus, Ulrich; Zimmermann, Julia L.

2013-01-01

113

Stability measurements of PPL atmospheric pressure arc  

SciTech Connect

Experiments on the stability of atmospheric pressure arcs have been started at PPL to understand and improve the performance of arc furnaces used for processing applications in metallurgy and hazardous waste treatment. Previous studies have suggested that the violent instabilities in such arcs may be due to kink modes. A 30 kW, 500 Amp CW DC experimental arc furnace was constructed with a graphite cathode and a molten steel anode. The arc plasma is diagnosed with 4000 frames/sec digital camera, Hall probes, and voltage and current monitors. Under certain conditions, the arc exhibits an intermittent helical instability, with the helix rotating at {approx}600 Hz. The nature of the instability is investigated. A possible instability mechanism is the self-magnetic field of the arc, with saturation occurring due to inhomogeneous heating in a helical arc. The effect of external DC and AC magnetic fields on the instability is investigated. Additionally, arc deflection due to external transverse magnetic field is investigated. The deflection angle is found to be proportional to the applied field, and is in good agreement with a simple model of the {rvec J} x {rvec b} force on the arc jet.

Roquemore, L.; Zweben, S.J. [Princeton Plasma Physics Lab., NJ (United States); Wurden, G.A. [Los Alamos National Lab., NM (United States)

1997-12-31

114

Medium resolution atmospheric pressure ionization mass spectrometer  

NASA Astrophysics Data System (ADS)

An atmospheric pressure ionization (API) source for a VG 7070E-HF mass spectrometer has been built and successfully operated at an accelerating potential of 6 kV. Hydrated protons and hydrated organic ions formed in the API source can be either partially or completely disaggregated by collisionally induced dissociation before entering the mass analyzer. The protonated molecular ions of pinacolone and 2,4-pentanedione can be fully separated (R=2800, m/z 101, <1% valley) at one sixth of their maximum signal strengths, and the 13C-xylene radical ion and protonated benzaldehyde can be fully separated (R=3300, m/z 107, <1% valley) at one tenth of their maximum signal strengths. With 1% transmission, the resolving power of the VG 7070E-HF operating in the API mode is estimated to be 4800 (m/z 92, 10% valley). This resolution is more than sufficient to separate two oxidized hydrocarbons whose masses differ by 0.0364 daltons, the difference between a -CH2CH2- group and a >CO group, and to permit unambiguous assignment of their molecular formulas. No other form of API mass spectrometer, including the triple quadrupole version, has this capability.

Grange, Andrew H.; O'Brien, Robert J.; Barofsky, Douglas F.

1988-04-01

115

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

Microsoft Academic Search

A hollow slot discharge operating in open air at atmospheric pressure has demonstrated its ability to deactivate bacterial growth on nearby surfaces exposed to the RF driven plasma. The cold plasma exits from a hollow slot with a width of 0.2 mm and variable length of 1-35 cm. An internal electrode was powered by 13.56 MHz radio-frequency power at a

Zengqi Yu; Amy Pruden; Ashish Sharma; George Collins

2003-01-01

116

Polarization Modulation Infrared Reflection Absorption Spectroscopy at Elevated Pressures: CO Adsorption on Pd(111) at Atmospheric Pressures  

E-print Network

Adsorption on Pd(111) at Atmospheric Pressures Emrah Ozensoy, Douglas C. Meier, and D. Wayne Goodman systems at or near the pressures of technical catalysts, that is, ambient (atmospheric) pressures. PMPolarization Modulation Infrared Reflection Absorption Spectroscopy at Elevated Pressures: CO

Goodman, Wayne

117

Quality characteristics of the radish grown under reduced atmospheric pressure  

Microsoft Academic Search

This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12kPa,

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

2008-01-01

118

Cold model characterisation of a fluidised bed catalytic reactor by means of instantaneous pressure measurements  

Microsoft Academic Search

The analysis of instantaneous pressure fluctuations is utilised in a cold modelling study of a pilot scale fluidised bed catalytic reactor for ethane oxychlorination. It is demonstrated that the fluid dynamic behaviour of a cold model of this fine particle (Geldart group A) system is well characterised by the frequency spectrum, the standard deviation and the cross-correlation of pressure signals

K. Gallucci; N. Jand; P. U. Foscolo; M. Santini

2002-01-01

119

Requirements for plasma synthesis of nanocrystals at atmospheric pressures  

NASA Astrophysics Data System (ADS)

While well-defined high quality semiconductor nanocrystals have been synthesized successfully in low pressure nonthermal plasmas, moving the field of plasma nanoparticle synthesis to atmospheric pressures is important for lowering its cost and making the process attractive for some industrial applications. Here we present a heating and charging model for silicon nanoparticles during their synthesis in plasmas maintained over a wide range of pressures (10 ? 105 Pa). We consider three collisionality regimes and determine the dominant contribution of each regime to heating and charging of nanoparticles under various plasma conditions. For plasmas maintained at atmospheric pressures we find that the ion current is mainly due to the collisional hydrodynamic contribution. Based on the model, we predict that the formation of nanocrystals at atmospheric pressure requires significantly higher plasma densities than those at low pressures. Strong nanoparticle cooling at atmospheric pressures necessitates high ion densities to reach temperatures required for crystallization of nanoparticles. Using experimentally determined plasma properties from the literature we estimate the nanoparticle temperature that can be achieved during synthesis at atmospheric pressures and predict that temperatures well above those required for crystallization can be achieved. Based on these results we suggest design principles for nanocrystal synthesis at atmospheric pressures.

Kramer, N. J.; Aydil, E. S.; Kortshagen, U. R.

2015-01-01

120

Effects of atmospheric pressure on the survival of photosynthetic microorganisms  

E-print Network

Effects of atmospheric pressure on the survival of photosynthetic microorganisms during simulations of Mars. The combination of low temperature, low pressure, high ultraviolet flux and extreme aridity would and heterotrophic bacteria could sur- vive under simulated ecopoesis conditions of pure CO2 at 100 mbar pressure

Thomas, Dave

121

Organic thin film deposition in atmospheric pressure glow discharge  

SciTech Connect

The stabilization of a homogeneous glow discharge at atmospheric pressure has been studied since 1987. On flat surfaces, various plasma surface treatments and film depositions at atmospheric pressure have been examined. A practical application of the atmospheric pressure glow plasma on inner surfaces of flexible polyvinyl chloride tubes was tested for thin film deposition of polytetrafluoroethylene. Deposited film surfaces were characterized by ESCA and FT-IR/ATR measurements. Also SEM observation was done for platelet adhesion on the plasma treated polyvinyl chloride surface. These results showed remarkable enhancement in the inhibition to platelet adhesion on the inner surface of PVC tube, and homogeneous organic film deposition was confirmed. The deposition mechanism of polytetrafluoroethylene film in atmospheric pressure glow plasma is the same as the mechanism of film formation in the low pressure glow plasma, except for radical formation source. {copyright} {ital 1996 American Institute of Physics.}

Okazaki, S.; Kogoma, M.; Yokoyama, T. [Sophia University, Kioi-cho 7-1, Chiyoda-ku, Tokyo 102 (Japan); Kodama, M. [Ministry of International Trade and Industry, Agency of Industrial Science and Technology, Higashi 1-1-4, Tsukuba-shi, Ibarki-k en 305 (Japan); Nomiyama, H.; Ichinohe, K. [Kawasumi Laboratories, Inc., Tamada 7-1, Miemachi, Ohno-gun, Ohita-ken 879-71 (Japan)

1996-01-01

122

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

123

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

124

Reduction of surface gravity data from global atmospheric pressure loading  

NASA Astrophysics Data System (ADS)

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

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

2002-05-01

125

Investigating Atmospheric Pressure with a Cup, Straw and Water  

NSDL National Science Digital Library

This activity is a reinforcement lab activity where students experiment with ways to get water to flow out of a cup and up a straw causing an imbalance in the atmospheric pressure surrounding the water.

126

Atmospheric Pressure Mass Spectrometry: A New Analytical  

E-print Network

acid) and to reduced N standards (allylurea; caffeine; imidazole; and N-2-propenylurea) occurred is an efficient removal mechanism for water- soluble chemical substances in the atmosphere. Since the early 1980s

Seitzinger, Sybil

127

Cold cathode gage experiment (lunar-atmosphere detector)  

NASA Technical Reports Server (NTRS)

A preliminary evaluation of the cold cathode gage experiment which was included in the ALSEP to determine the amount of gas present on the lunar surface is reported. The instrument, electronic circuitry, and deployment are described. The preliminary results are summarized and include temperature history, and variations in gas concentration detected after deployment.

Johnson, F. S.; Evans, D. E.; Carroll, J. M.

1972-01-01

128

Measuring Viscosities of Gases at Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

129

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

130

Optical and Electrical Measurements in Atmospheric Pressure Arcs: a Comparison  

Microsoft Academic Search

Atmospheric pressure arcs are investigated by emission spectroscopy and electric exploration techniques. Temperature maps for arc currents in the range 100-200 A show good agreement with previously published data. An extended study on Langmuir probes in arcs has been performed and a multi-wire apparatus was constructed. The probes characteristic curve is distorted at high pressure and as a consistent theory

Carlo Fanara; Louriel Oliveira Vilarinho

2002-01-01

131

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

132

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

133

A simplified system of pressure surfaces for atmospheric analysis  

E-print Network

in current procedure, arbitrarily divided the atmosphere into layers of pressure difference of 100 millibars from 1000 to 100 mil- libars. This division of the atmosphere into layers 100 millibars thick was'made for several reasons. Pressures then were... Use of Pro osed S stem In order to demonstrate the applicability of the new system, the data for 0300 GCT2 23 January 1957 in the current system were used to construct a set of constant pressure charts based on Set 5 (Table E). Dpp -t 2 t I D~tl 2...

Shay, Francis Schofield

2012-06-07

134

Tantalum Etching with an Atmospheric Pressure Plasma Jet  

NASA Astrophysics Data System (ADS)

The APPJ is a non-thermal, atmospheric-pressure, glow discharge. A feedgas, composed of an inert carrier gas (e.g., He) and small concentrations of additives (e.g., O2, or CF4), flows between closely spaced electrodes powered at 13.56 MHz rf in a coaxial or parallel plate arrangement. The plasma has Te ˜ 2 eV and ne ˜ 10^11 cm-3. Electrons are not in thermal equilibrium with ions and neutrals: the electrons are ``hot", while the overall gas temperature is quite ``cold", typically 50-300 C. In the plasma, the gas is excited, dissociated or ionized by energetic electron impact. As the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, leaving metastables (e.g. O2*, He*) and radicals (e.g. O, F, OF, O2F, CFO). These reactive species are then directed onto a surface to be processed. The APPJ has been developed for decontaminating nuclear, chemical, and biological agents. Atomic fluorine, and possibly other reactive species, can be used to convert actinides (e.g., U and Pu), into volatile fluorides (e.g., UF6, PuF6) that can be trapped, resulting in significant volume reduction of radioactive waste. In this talk, we will present results on using Ta as a surrogate for Pu in He/O2/CF4 etching plasmas. Results of experimental measurements of Ta etch rates for various gas mixtures and plasma jet standoff distance will be compared with plasma chemistry modeling of the concentrations of several active species produced in the plasma.

Teslow, Hilary; Herrmann, Hans; Rosocha, Louis

2002-10-01

135

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

136

A possible mechanism for cold denaturation of proteins at high pressure  

E-print Network

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 ($\\approx2$ kbar), 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.

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

2003-06-11

137

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

SciTech Connect

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

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

2013-05-15

138

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

139

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

140

A Spectacular Experiment Exhibiting Atmospheric Pressure  

ERIC Educational Resources Information Center

The experiment described here is fairly easy to reproduce and dramatically shows the magnitude of ambient air pressure. Two circular plates of aluminum are applied one against the other. How do you make their separation very difficult? With only the help of an elastic band! You don't have to use a vacuum pump for this experiment.

Le Noxaïc, Armand

2014-01-01

141

Application of Relationship Between Groundwater Level and Atmospheric Pressure Change  

NASA Astrophysics Data System (ADS)

Change in atmospheric pressure affects ground water levels. Barometric efficiency, which is an indicator for different exposure to the atmospheric pressure of observation well and adjacent ground cover, can be used as an effective tool for estimating some groundwater properties. If the top of an observation well is sealed and contact with the atmosphere is blocked, there would be no pressure difference between the well and adjacent ground cover. As a result, the difference between barometric efficiency values of sealed and unsealed well of identical condition can indicates the effect of atmospheric pressure changes on the groundwater level. One month observation data of hydraulic head and atmospheric pressure at Wonju-si in Gangwon-do, Korea are used. Two different methods, Clark's method and graphical method, are adopted to estimate the barometric efficiency. Because the efficiency has implication on the properties of aquifer covering condition, mapping of this efficiency might be used for estimating groundwater vulnerability of contamination from surface-loaded sources.

Kim, S. J.; Lee, K.

2013-12-01

142

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...

143

High pressure ignition of boron in reduced oxygen atmospheres  

SciTech Connect

Boron ignition delay times for 24 {micro}m diameter particles have been measured behind the reflected shock at a shock tube endwall in reduced oxygen atmospheres and in a combustion bomb at higher pressures in the products of a hydrogen/oxygen/nitrogen reaction. The shock tube study independently varies temperature (1,400 -- 3,200 K), pressure (8.5, 34 atm), and ignition-enhancer additives (water vapor, fluorine compounds). A combustion chamber is used at a peak pressure of 157 atm and temperature in excess of 2,800 K to study ignition delays at higher pressures than are possible in the shock tube.

Foelsche, R.O.; Spalding, M.J.; Burton, R.L.; Krier, H. [Univ. of Illinois, Urbana, IL (United States)

1996-07-01

144

Plant adaptation to low atmospheric pressures: potential molecular responses  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

146

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

147

Diffuse ?-mode atmospheric pressure radio-frequency discharge in neon  

NASA Astrophysics Data System (ADS)

In this work, a radio-frequency (RF) atmospheric pressure glow discharge burning in neon between planar metal electrodes is achieved for the first time. The RF discharge can operate in two stable modes: in a diffuse ?-mode with uniformly covered electrode surfaces and in a constricted ?-mode. Similarities are revealed when the discharge is compared against the RF atmospheric pressure glow discharge in helium, namely both discharges show a discontinuity and a hysteresis in the current-voltage characteristic at the mode transition; the spatio-temporal profiles of the light emission in the ?-mode from neon, helium and atomic oxygen are also similar.

Navrátil, Z.; Dosoudilová, L.; Josepson, R.; Dvo?ák, P.; Trunec, D.

2014-08-01

148

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

149

Peptide Fragmentation Induced by Radicals at Atmospheric Pressure  

PubMed Central

A novel ion dissociation technique, which is capable of providing an efficient fragmentation of peptides at essentially atmospheric pressure conditions, is developed. The fragmentation patterns observed often contain c-type fragments that are specific to ECD/ETD, along with the y-/b- fragments that are specific to CAD. In the presented experimental setup, ion fragmentation takes place within a flow reactor located in the atmospheric pressure region between the ion source and the mass spectrometer. According to a proposed mechanism, the fragmentation results from the interaction of ESI-generated analyte ions with the gas-phase radical species produced by a corona discharge source. PMID:19034885

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

2009-01-01

150

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

151

On the permanent hip-stabilizing effect of atmospheric pressure.  

PubMed

Hip joint dislocations related to total hip arthroplasty (THA) are a common complication especially in the early postoperative course. The surgical approach, the alignment of the prosthetic components, the range of motion and the muscle tone are known factors influencing the risk of dislocation. A further factor that is discussed until today is atmospheric pressure which is not taken into account in the present THA concepts. The aim of this study was to investigate the impact of atmospheric pressure on hip joint stability. Five joint models (Ø 28-44 mm), consisting of THA components were hermetically sealed with a rubber capsule, filled with a defined amount of fluid and exposed to varying ambient pressure. Displacement and pressure sensors were used to record the extent of dislocation related to intraarticular and ambient pressure. In 200 experiments spontaneous dislocations of the different sized joint models were reliably observed once the ambient pressure was lower than 6.0 kPa. Increasing the ambient pressure above 6.0 kPa immediately and persistently reduced the joint models until the ambient pressure was lowered again. Displacement always exceeded half the diameter of the joint model and was independent of gravity effects. This experimental study gives strong evidence that the hip joint is permanently stabilized by atmospheric pressure, confirming the theories of Weber and Weber (1836). On basis of these findings the use of larger prosthetic heads, capsular repair and the deployment of an intracapsular Redon drain are proposed to substantially decrease the risk of dislocation after THA. PMID:24938930

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

2014-08-22

152

Designing Extraterrestrial Plant Growth Habitats With Low Pressure Atmospheres  

NASA Technical Reports Server (NTRS)

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

Corey, Kenneth A.

2001-01-01

153

Designing Extraterrestrial Plant Growth Habitats with Low Pressure Atmospheres  

NASA Technical Reports Server (NTRS)

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

Corey, Kenneth A.

2002-01-01

154

Atmospheric Pressure Plasma Jet Treatment of Polyethylene Surfaces for  

E-print Network

, composite materials and metals need a pretreatment step before adhesive bonding or painting.[1 analysis and adhesive bonding experiments. The plasma is characterized by optical emission spectroscopy) samples were activated by an atmospheric pressure plasma jet. The improvement in adhesive bond strength

Greifswald, Ernst-Moritz-Arndt-Universität

155

Atmospheric pressure and suicide attempts in Helsinki, Finland  

NASA Astrophysics Data System (ADS)

The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods ( P < 0.001), and may explain the clustering of suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

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

2012-11-01

156

Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

157

The Water Table As Affected by Atmospheric Pressure  

Microsoft Academic Search

In the common situation where air is entrapped in the water, the water table height will vary with atmospheric pressure. The magnitude of this effect must be known before water-table changes can be related with any precision to other factors such as evapo- transpiration, infiltration, and drainage. A theory of this effect is developed and the influences of hysteresis and

A. J. Peck

1960-01-01

158

TOPICAL REVIEW: Non-thermal atmospheric pressure discharges  

Microsoft Academic Search

There has been considerable interest in non-thermal atmospheric pressure discharges over the past decade due to the increased number of industrial applications. Diverse applications demand a solid physical and chemical understanding of the operational principals of such discharges. This paper focuses on the four most important and widely used varieties of non-thermal discharges: corona, dielectric barrier, gliding arc and spark

A. Fridman; A. Chirokov; A. Gutsol

2005-01-01

159

Gravity and Atmospheric Pressure Effects on Crater Formation in Sand  

Microsoft Academic Search

An experimental investigation was conducted to determine the effects of varying gravity and atmospheric pressure on the size of small explosion craters formed in cohesionless sand. The explosives used were commercially available squibs and caps and a linear detonating cord. Gravity was varied by flying the test container in an aircraft through carefully controlled maneuvers to simulate 0.17, 0.38, and

S. W. Johnson; J. A. Smith; E. G. Franklin; L. K. Moraski; D. J. Teal

1969-01-01

160

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

Microsoft Academic Search

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

H. Wexler; W. A. Hass

1962-01-01

161

Bacterial Inactivation by Atmospheric Pressure Dielectric Barrier Discharge Plasma Jet  

Microsoft Academic Search

Bacillus subtilis and Escherichia coli seeded in two media (agar and filter papers) were exposed to after-glow plasma emitted from a atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator in open air with a temperature of about 30-80 °C. In order to estimate the inactivation of microorganism using DBD plasma jet, various plasma conditions (such as treatment time and

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

2008-01-01

162

Controlling the NO production of an atmospheric pressure plasma jet  

Microsoft Academic Search

The production of NO radicals by an atmospheric pressure plasma jet has been investigated by means of absorption spectroscopy in the mid-infrared region (IR) and optical emission spectroscopy (OES) in the ultraviolet (UV) part of the spectrum. The plasma jet investigated here operates in argon with air admixtures up to 1%. The study shows that OES can be used to

A V Pipa; S Reuter; R Foest; K-D Weltmann

2012-01-01

163

An Introduction to Nonequilibrium Plasmas at Atmospheric Pressure  

E-print Network

Distributions Plasmas are increasingly used for chemical processing of gases such as air, combustion exhaust into specific excitations and reactions. Recent examples include the optimization of the Plasma Chemistry1 1 An Introduction to Nonequilibrium Plasmas at Atmospheric Pressure Sander Nijdam, Eddie van

Ebert, Ute

164

ANNUAL REPORT. ATMOSPHERIC-PRESSURE PLASMA CLEANING OF CONTAMINATED SURFACES  

EPA Science Inventory

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

165

Bacterial Inactivation Using an RF-Powered Atmospheric Pressure Plasma  

Microsoft Academic Search

Cells of Escherichia coli were exposed to a downstream plasma afterglow plume emitted from a slotted plasma device operating in open air at atmospheric pressure. Various feed-gas mixtures were capacitively excited, as they flowed into open air past radio frequency-powered electrodes. To estimate the underlying inactivation pathways, various experimental conditions were tested by incorporating ultraviolet filters, varying parameters such as

A. Sharma; A. Pruden; O. Stan; G. J. Collins

2006-01-01

166

Atmospheric Pressure Infrared MALDI Imaging Mass Spectrometry for Plant Metabolomics  

E-print Network

in the citric acid cycle. Key components of the glycolysis pathway occurring in the plant cytosol were found#12;Atmospheric Pressure Infrared MALDI Imaging Mass Spectrometry for Plant Metabolomics Yue Li MALDI mass spectrometry (AP IR-MALDI) was assessed for plant metabolomics studies. Tissue sections from

Vertes, Akos

167

Excitation dynamics of micro-structured atmospheric pressure plasma arrays  

Microsoft Academic Search

The spatial dynamics of the optical emission from an array of 50 times 50 individual microcavity plasma devices is investigated. The array is operated in argon and argon-neon mixtures close to atmospheric pressure with an ac voltage. The optical emission is analysed with phase and space resolution. It has been found that the emission is not continuous over the entire

H. Boettner; J. Waskoenig; D. O'Connell; T. L. Kim; P. A. Tchertchian; J. Winter; V. Schulz-von der Gathen

2010-01-01

168

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

169

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

170

Accurate pressure gradient calculations in hydrostatic atmospheric models  

NASA Technical Reports Server (NTRS)

A method for the accurate calculation of the horizontal pressure gradient acceleration in hydrostatic atmospheric models is presented which is especially useful in situations where the isothermal surfaces are not parallel to the vertical coordinate surfaces. The present method is shown to be exact if the potential temperature lapse rate is constant between the vertical pressure integration limits. The technique is applied to both the integration of the hydrostatic equation and the computation of the slope correction term in the horizontal pressure gradient. A fixed vertical grid and a dynamic grid defined by the significant levels in the vertical temperature distribution are employed.

Carroll, John J.; Mendez-Nunez, Luis R.; Tanrikulu, Saffet

1987-01-01

171

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.

172

Model of a stationary microwave argon discharge at atmospheric pressure  

SciTech Connect

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

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

2008-03-19

173

A Micromachined Pressure Sensor with Integrated Resonator Operating at Atmospheric Pressure  

PubMed Central

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

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

2013-01-01

174

Non-Thermal Atmospheric-Pressure Plasma Possible Application in Wound Healing  

PubMed Central

Non-thermal atmospheric-pressure plasma, also named cold plasma, is defined as a partly ionized gas. Therefore, it cannot be equated with plasma from blood; it is not biological in nature. Non-thermal atmospheric-pressure plasma is a new innovative approach in medicine not only for the treatment of wounds, but with a wide-range of other applications, as e.g. topical treatment of other skin diseases with microbial involvement or treatment of cancer diseases. This review emphasizes plasma effects on wound healing. Non-thermal atmospheric-pressure plasma can support wound healing by its antiseptic effects, by stimulation of proliferation and migration of wound relating skin cells, by activation or inhibition of integrin receptors on the cell surface or by its pro-angiogenic effect. We summarize the effects of plasma on eukaryotic cells, especially on keratinocytes in terms of viability, proliferation, DNA, adhesion molecules and angiogenesis together with the role of reactive oxygen species and other components of plasma. The outcome of first clinical trials regarding wound healing is pointed out. PMID:25489414

Haertel, Beate; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Lindequist, Ulrike

2014-01-01

175

Non-thermal atmospheric-pressure plasma possible application in wound healing.  

PubMed

Non-thermal atmospheric-pressure plasma, also named cold plasma, is defined as a partly ionized gas. Therefore, it cannot be equated with plasma from blood; it is not biological in nature. Non-thermal atmospheric-pressure plasma is a new innovative approach in medicine not only for the treatment of wounds, but with a wide-range of other applications, as e.g. topical treatment of other skin diseases with microbial involvement or treatment of cancer diseases. This review emphasizes plasma effects on wound healing. Non-thermal atmospheric-pressure plasma can support wound healing by its antiseptic effects, by stimulation of proliferation and migration of wound relating skin cells, by activation or inhibition of integrin receptors on the cell surface or by its pro-angiogenic effect. We summarize the effects of plasma on eukaryotic cells, especially on keratinocytes in terms of viability, proliferation, DNA, adhesion molecules and angiogenesis together with the role of reactive oxygen species and other components of plasma. The outcome of first clinical trials regarding wound healing is pointed out. PMID:25489414

Haertel, Beate; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Lindequist, Ulrike

2014-11-01

176

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

177

Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2  

E-print Network

1 Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2-dominated atmosphere, but direct constraints on paleoatmospheric11 pressure P are lacking. Of particular doubtful that increasing CO2 pressure (total atmospheric pressure, P) is enough to raise early39 Mars

Kite, Edwin

178

Atmospheric pressure plasma jet: Effect of electrode configuration, discharge behavior, and its formation mechanism  

E-print Network

Atmospheric pressure plasma jet: Effect of electrode configuration, discharge behavior, and its 2008; accepted 8 June 2009; published online 10 July 2009 Atmospheric pressure plasma jet APPJ can The atmospheric pressure plasma is much advantageous over low pressure plasmas in various aspects. It can be dis

Zexian, Cao

179

Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2  

E-print Network

1 Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2-dominated atmosphere, but direct constraints on paleoatmospheric11 pressure P are lacking1 that increasing CO240 pressure (total atmospheric pressure, P) is enough to raise early Mars mean

Kite, Edwin

180

Atmospheric pressure loading parameters from very long baseline interferometry observations  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

181

Influence of Atmospheric Pressure and Composition on LIBS  

SciTech Connect

Most LIBS experiments are conducted at standard atmospheric pressure in air. However, there are LIBS studies that vary the pressure and composition of the gas. These studies have provided insights into fundamentals of the mechanisms that lead to the emission and methods for improving the quality of LIBS spectra. These atmospheric studies are difficult because the effects of pressure and gas composition and interconnected, making interpretation of the results difficult. The influence of pressures below and above 760 Torr have been explored. Performing LIBS on a surface at reduced pressures (<760 Torr) can result in enhanced spectra due to higher resolution, increased intensity, improved signal-to-noise (S/N), and increased ablation. Lower pressures produce increased resolution because the line width in LIBS spectra is predominantly due to Stark and Doppler broadening. Stark broadening is primarily caused from collisions between electrons and atoms, while Doppler broadening is proportional to the plasma temperature. Close examination using a high resolution spectrometer reveals that spectra show significant peak broadening and self-absorption as pressures increase, especially for pressures >760 Torr. During LIBS plasma expansion, energy is lost to the surrounding atmosphere, which reduces the lifetime of the laser plasma. Therefore, reducing the pressure increases the lifetime of the plasma, allowing more light from the laser plasma to be collected; thus, increasing the observed signal intensity. However, if pressures are too low (<10 Torr), then there is a steep drop in LIBS spectral intensity. This loss in intensity is mostly due to a disordered plasma that results from the lack of sufficient atmosphere to provide adequate confinement. At reduced pressures, the plasma expands into a less dense atmosphere, which results in a less dense shock wave. The reduced density in the shock wave results in reduced plasma shielding, allowing more photons to reach the sample. Increasing the number of photons interacting with the sample surface results in increased ablation, which can lead to increased intensity. The composition of the background gas has been shown to greatly influence the observed LIBS spectra by altering the plasma temperature, electron density, mass removal, and plasma shielding that impact the emission intensity and peak resolution. It has been reported that atmospheric Ar results in the highest plasma temperature and electron density, while a He atmosphere results in the lowest plasma temperatures and electron density. Studying temporal data, it was also found that Ar had the slowest decay of both electron density and plasma temperature, while He had the fastest decay in both parameters. The higher plasma temperature and electron density results in an increase in line broadenin, or poor resolution, for Ar compared to He. A rapidly developing LIBS plasma with a sufficient amount of electrons can absorb a significant portion of the laser pulse through inverse Bremsstahlung. Ar (15.8 eV ) is more easily ionized than He (24.4 eV). The breakdown threshold for He at 760 Torr is approximately 3 times greater than Ar and approximately 5 times greater at 100 Torr. The lower breakdown threshold in Ar, compared to He, creates an environment favorable for plasma shielding, which reduces sample vaporization and leads to a weaker LIBS signal.

Jeremy J. Hatch [Pacific Univ., Forest Grove, OR (United States). Dept. of Chemistry; Jill R. Scott [Idaho National Laboratory (INL), Idaho Falls, ID (United States). Chemical and Radiation Measurement; Effenberger, A. J. Jr. [Univ. of California, San Diego, CA (United States). Center for Energy Research

2014-03-01

182

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

183

Exploration Spacecraft and Space Suit Internal Atmosphere Pressure and Composition  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

184

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

185

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

186

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

Microsoft Academic Search

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

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

2010-01-01

187

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

Microsoft Academic Search

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the

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

2009-01-01

188

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

Microsoft Academic Search

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium–oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the

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

2009-01-01

189

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

190

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

191

Possible Mechanism for Cold Denaturation of Proteins at High Pressure Manuel I. Marques,1,* Jose M. Borreguero,1  

E-print Network

Possible Mechanism for Cold Denaturation of Proteins at High Pressure Manuel I. Marque´s,1,* Jose M (Received 10 February 2003; published 26 September 2003) We study cold denaturation of proteins at high freezes to the dense ice phase ( 2 kbars) the mechanism for cold denaturation with decreasing temperature

Dokholyan, Nikolay V.

192

Cellular membrane collapse by atmospheric-pressure plasma jet  

SciTech Connect

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

Kim, Kangil; Sik Yang, Sang, E-mail: jsjlee@ajou.ac.kr, E-mail: ssyang@ajou.ac.kr [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Jun Ahn, Hak; Lee, Jong-Soo, E-mail: jsjlee@ajou.ac.kr, E-mail: ssyang@ajou.ac.kr [Department of Biological Sciences, Ajou University, Suwon 443-749 (Korea, Republic of)] [Department of Biological Sciences, Ajou University, Suwon 443-749 (Korea, Republic of); Lee, Jae-Hyeok; Kim, Jae-Ho [Department of Molecular Science and Technology, Ajou University, Suwon 443-749 (Korea, Republic of)] [Department of Molecular Science and Technology, Ajou University, Suwon 443-749 (Korea, Republic of)

2014-01-06

193

Cold atmospheric plasma treatment selectively targets head and neck squamous cell carcinoma cells.  

PubMed

The treatment of locoregional recurrence (LRR) of head and neck squamous cell carcinoma (HNSCC) often requires a combination of surgery, radiation therapy and/or chemotherapy. Survival outcomes are poor and the treatment outcomes are morbid. Cold atmospheric plasma (CAP) is an ionized gas produced at room temperature under laboratory conditions. We have previously demonstrated that treatment with a CAP jet device selectively targets cancer cells using in vitro melanoma and in vivo bladder cancer models. In the present study, we wished to examine CAP selectivity in HNSCC in vitro models, and to explore its potential for use as a minimally invasive surgical approach that allows for specific cancer cell or tumor tissue ablation without affecting the surrounding healthy cells and tissues. Four HNSCC cell lines (JHU-022, JHU-028, JHU-029, SCC25) and 2 normal oral cavity epithelial cell lines (OKF6 and NOKsi) were subjected to cold plasma treatment for durations of 10, 30 and 45 sec, and a helium flow of 20 l/min-1 for 10 sec was used as a positive treatment control. We showed that cold plasma selectively diminished HNSCC cell viability in a dose-response manner, as evidenced by MTT assays; the viability of the OKF6 cells was not affected by the cold plasma. The results of colony formation assays also revealed a cell-specific response to cold plasma application. Western blot analysis did not provide evidence that the cleavage of PARP occurred following cold plasma treatment. In conclusion, our results suggest that cold plasma application selectively impairs HNSCC cell lines through non-apoptotic mechanisms, while having a minimal effect on normal oral cavity epithelial cell lines. PMID:25050490

Guerrero-Preston, Rafael; Ogawa, Takenori; Uemura, Mamoru; Shumulinsky, Gary; Valle, Blanca L; Pirini, Francesca; Ravi, Rajani; Sidransky, David; Keidar, Michael; Trink, Barry

2014-10-01

194

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

195

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

196

Imaging of atmospheric pressure glow discharges in helium and argon  

Microsoft Academic Search

We present images of atmospheric pressure glow discharges (APGD) in pure noble gases, helium and argon, for a needle-plane (N-P) electrode geometry. The images have been obtained using an intensified charge-coupled device (ICCD) digital camera, at nanosecond exposure times. We present time-dependence of discharge images perpendicular and parallel to the interelectrode gap for both helium and argon.

I. Radu; R. Bartnikas; M. R. Wertheimer

2005-01-01

197

Plasma sterilization using glow discharge at atmospheric pressure  

Microsoft Academic Search

Recent development of atmospheric pressure glow discharge was compared with the performance of an apparatus used in the first APG experiment, in terms of sterilization of newly classified biological indicator: Bacillus atrophaeus, former Bacillus subtilis var. niger and Geobacillus stearothermophilus. Stabilization was attained by controlling the experimental conditions, at low frequency: 100 kHz and Radio Frequency: 13.56 MHz, water vapor\\/He

Tetsuya Akitsu; Hiroshi Ohkawa; Masao Tsuji; Hideo Kimura; Masuhiro Kogoma

2005-01-01

198

Double streamer phenomena in atmospheric pressure low frequency corona plasma  

SciTech Connect

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

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

2010-07-15

199

Low pressure and atmospheric pressure plasma-jet systems and their application for deposition of thin films  

E-print Network

atmospheric discharge plasma jet. This system works at open air without any vacuum system. This system1 Low pressure and atmospheric pressure plasma-jet systems and their application for deposition on polymer substrates. Under certain condition in the atmospheric plasma jet, these films have crystalline

Paris-Sud XI, Université de

200

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

PubMed

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

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

2013-01-29

201

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

202

Transmission geometry laserspray ionization vacuum using an atmospheric pressure inlet.  

PubMed

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

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

2014-07-01

203

NO production in an RF plasma jet at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A time modulated RF atmospheric pressure plasma jet, operated in ambient air with a flow of argon with a few per cent of air, N2 or O2, was characterized by measuring the gas temperature with Rayleigh scattering, the absolute NO density with laser-induced fluorescence, and the emission of NO A and N2 C with time resolved optical emission spectroscopy. The gas temperature, NO density and the emission measurements are carried out both time and spatially resolved. The atmospheric pressure plasma jet has the advantage that the plasma dissipated power can be measured, and it was found that the gas temperature depends on the power, rather than the gas mixture. The NO density increases with increasing plasma power, and was found to have a maximum around 1.5 × 1021 m-3 at an air admixture of 2%. The N2 C emission is modulated by the 13.9 MHz RF frequency, while the NO A emission front increases with much slower velocity during the 20 kHz duty cycle, which gives an insight into the excitation mechanisms in the plasma. Through the addition of either N2 or O2 to the plasma it was experimentally confirmed that the production of atomic N radicals are of key importance for the NO production in this atmospheric pressure plasma jet.

van Gessel, A. F. H.; Alards, K. M. J.; Bruggeman, P. J.

2013-07-01

204

Atmospheric pressure loading effects on Global Positioning System coordinate determinations  

NASA Technical Reports Server (NTRS)

Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65 deg), with a signal root mean square (RMS) of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements. Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Removing the modeled pressure loading from GPS determinations of baseline length for baselines longer than 6000 km reduces the variance on 73 of the 117 baselines investigated. The slight increase in variance for some of the sites and baselines is consistent with expected statistical fluctuations. The results from most stations are consistent with approximately 65% of the modeled pressure load being found in the GPS vertical position measurements. Removing an annual signal from both the measured heights and the modeled load time series leaves this value unchanged. The source of the remaining discrepancy between the modeled and observed loading signal may be the result of (1) anisotropic effects in the Earth's loading response, (2) errors in GPS estimates of tropospheric delay, (3) errors in the surface pressure data, or (4) annual signals in the time series of loading and station heights. In addition, we find that using site dependent coefficients, determined by fitting local pressure to the modeled radial displacements, reduces the variance of the measured station heights as well as or better than using the global convolution sum.

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

1994-01-01

205

Aerosol-assisted atmospheric cold plasma deposition and characterization of superhydrophobic organic-inorganic nanocomposite thin films.  

PubMed

A facile atmospheric pressure cold plasma process is presented to deposit a novel organic-inorganic hydrocarbon polymer/ZnO nanoparticles nanocomposite coating. Specifically, this method involves the utilization of an atmospheric pressure dielectric barrier discharge (DBD) fed with helium and the aerosol of a dispersion of oleate-capped ZnO nanoparticles (NPs) in n-octane. As assessed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, the deposited nanocomposite coating combines the chemical features of both the oleate-capped ZnO NPs and the polyethylene-like organic component originated from the plasma polymerization of n-octane. Additionally, scanning electron microscopy (SEM) and transmission scanning electron microscopy (TSEM) confirm the synthesis of hierarchical micro/nanostructured coatings containing quasi-spherical NPs agglomerates. The polyethylene-like polymer covers the NPs agglomerates to different extents and contributes to their immobilization in the three-dimensional network of the coating. The increase of both the deposition time (1-10 min) and the NPs concentration in the dispersion (0.5-5 wt %) has a significant effect on the chemical and morphological structure of the thin films and, in fact, results in the increase the ZnO NPs content, which ultimately leads to superhydrophobic surfaces (advancing and receding water contact angles higher than 160°) with low hysteresis due to the hierarchical multiscale roughness of the coating. PMID:24393041

Fanelli, Fiorenza; Mastrangelo, Anna M; Fracassi, Francesco

2014-01-28

206

Vortex Threshold: Experimental Results at Martian Atmospheric Pressures  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

207

Phase explosion in atmospheric pressure infrared laser ablation from water-rich targets  

E-print Network

Phase explosion in atmospheric pressure infrared laser ablation from water-rich targets Zhaoyang for preparative, medical,13 and analytical applications11 e.g., atmospheric pressure matrix-assisted laser at atmospheric pressure in the presence of phase ex- plosion. Compared to laser ablation in vacuum, in a back

Vertes, Akos

208

Simulation of a direct current microplasma discharge in helium at atmospheric pressure  

E-print Network

Simulation of a direct current microplasma discharge in helium at atmospheric pressure Qiang Wang at atmospheric pressure was performed based on a one-dimensional fluid model. The microdischarge was found dc atmospheric pressure He microdischarge were presented, as well as successful comparisons

Economou, Demetre J.

209

Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure  

E-print Network

at atmospheric pressure A. Sáinz1 , J. Margot2 , M. C. García1 , M. D. Calzada1 1 Grupo de Espectroscopía de+ ) are also expected to play an important role in the discharge kinetics. At atmospheric pressure obeys the Saha-Boltzmann distribution. However, at atmospheric pressure, molecular recombination

Boyer, Edmond

210

Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization in Transmission Geometry  

E-print Network

Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization in Transmission Geometry Marsha C, Washington, D.C. 20375 In both atmospheric pressure matrix-assisted laser de- sorption/ionization (AP MALDI a significant impediment. Atmospheric pressure (AP) MALDI promises to eliminate the need for this step.1

Vertes, Akos

211

Video Article Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by  

E-print Network

Video Article Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI.3791/2097 Citation: Nemes P., Vertes A. (2010). Atmospheric-pressure Molecular Imaging of Biological Tissues with an atmospheric-pressure ion source interface is employed to analyze and record the composition of the released

Vertes, Akos

212

Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass  

E-print Network

Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass. For example, atmospheric pressure infrared MALDI (AP IR-MALDI), capable of producing ions from small ionization (DESI),5 desorption atmospheric pressure chemical ionization (DAPCI),6 and matrix- assisted laser

Vertes, Akos

213

Dynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges  

E-print Network

Dynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges of pulse phenomena in conventional parallel-plate dielectric-barrier controlled atmospheric-pressure glow. DOI: 10.1063/1.1625414 I. INTRODUCTION There is rapidly growing interest in atmospheric- pressure glow

Raja, Laxminarayan L.

214

Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges  

E-print Network

Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges Xiaohui 2002 A computational study of capacitively coupled atmospheric-pressure glow discharges in high atmospheric-pressure glow discharges. © 2002 American Institute of Physics. DOI: 10.1063/1.1497445 Several

Raja, Laxminarayan L.

215

An atmospheric pressure ion lens to improve electrospray ionization at low solution ow-rates  

E-print Network

An atmospheric pressure ion lens to improve electrospray ionization at low solution ¯ow by the addition of an atmospheric pressure ion lens near the tip of the tapered sprayer. The magnitude, but no discussion was given as to whether it increased the ion signals. Franzen used an atmospheric pressure ring

Chen, David D.Y.

216

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

217

Time and space variability of spectral estimates of atmospheric pressure  

NASA Technical Reports Server (NTRS)

The temporal and spatial behaviors of atmospheric pressure spectra over the northern Italy and the Alpine massif were analyzed using data on surface pressure measurements carried out at two microbarograph stations in the Po Valley, one 50 km south of the Alps, the other in the foothills of the Dolomites. The first 15 days of the study overlapped with the Alpex Intensive Observation Period. The pressure records were found to be intrinsically nonstationary and were found to display substantial time variability, implying that the statistical moments depend on time. The shape and the energy content of spectra depended on different time segments. In addition, important differences existed between spectra obtained at the two stations, indicating a substantial effect of topography, particularly for periods less than 40 min.

Canavero, Flavio G.; Einaudi, Franco

1987-01-01

218

Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology  

NASA Technical Reports Server (NTRS)

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

Button, Amy; Sweterlisch, Jeffery J.

2013-01-01

219

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

220

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

221

Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool in laser evaporation methods  

E-print Network

Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool introduced analytical method, atmospheric pressure matrix-assisted laser desorption ionization (AP- MALDI write; Atmospheric pressure MALDI; Laser evaporation; Plume diagnostics 1. Introduction Diagnostics

Vertes, Akos

222

Atmospheric Pressure Humid Argon DBD Plasma for the Application of Sterilization -Measurement and Simulation of Hydrogen, Oxygen, and Hydrogen  

E-print Network

Atmospheric Pressure Humid Argon DBD Plasma for the Application of Sterilization - Measurement peroxide have been measured downstream of an atmospheric pressure humid argon dielectric barrier discharge, sterilization I. INTRODUCTION Non-thermal plasma technology at atmospheric pressure using oxygen

Paris-Sud XI, Université de

223

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

2011-09-30

224

Stable microwave coaxial cavity plasma system at atmospheric pressure.  

PubMed

We present a systematic study of the development of a novel atmospheric microwave plasma system for material processing in the pressure range up to 760 torr and the microwave input power up to 6 kW. Atmospheric microwave plasma was reliably produced and sustained by using a cylindrical resonator with the TM(011) cavity mode. The applicator and the microwave cavity, which is a cylindrical resonator, are carefully designed and optimized with the time dependent finite element Maxwell equation solver. The azimuthal apertures are placed at the maximum magnetic field positions between the cavity and the applicator to maximize the coupling efficiency into the microwave plasma at a resonant frequency of 2.45 GHz. The system consists of a magnetron power supply, a circulator, a directional coupler, a three-stub tuner, a dummy load, a coaxial cavity, and a central cavity. Design and construction of the resonant structures and diagnostics of atmospheric plasma using optical experiments are discussed in various ranges of pressure and microwave input power for different types of gases. PMID:18513083

Song, H; Hong, J M; Lee, K H; Choi, J J

2008-05-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

226

Oxygen transport through polyethylene terephthalate (PET) coated with plasma-polymerized acetylene at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate.ootnotetextE.M. Moser, R. Urech, E. Hack, H. K"unzli, E. M"uller, Thin Solid Films, 317, 1998, pp. 388-392. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 ?m. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film.

Wemlinger, Erik; Pedrow, Patrick; Garcia-Pérez, Manuel; Sablani, Shyam

2011-11-01

227

Atmospheric H2O2 measurement: comparison of cold trap method with impinger bubbling method  

NASA Technical Reports Server (NTRS)

Collection of atmospheric H2O2 was performed by a cold trap method using dry ice-acetone as the refrigerant. The air was drawn by a pump into a glass gas trap immersed in the dry ice-acetone slush in a dewar flask at a flow rate of 2.5 l min-1 for approximately 2 h. Collection efficiency was > 99% and negligible interferences by O3, SO2 or organic matter with the collected H2O2 in the trap were observed. This method was compared with the air impinger bubbling method which has been previously described (Kok et al., 1978a, b, Envir. Sci. Technol. 12, 1072-1080). The measured total peroxide (H2O2 + organic peroxide) values in a series of aim samples collected by the impinger bubbling method (0.06-3.7 ppb) were always higher than those obtained by the cold trap method (0.02-1.2 ppb). Laboratory experiments suggest that the difference in values between the two methods probably results from the aqueous phase generation of H2O2 and organic peroxide in the impinger solution by a reaction of atmospheric O3 with olefinic and aromatic compounds. If these O3-organic compound reactions which occur in the impinger also occur in aqueous droplets in the atmosphere, the process could be very important for aqueous phase generation of H2O2 in clouds and rainwater.

Sakugawa, H.; Kaplan, I. R.

1987-01-01

228

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

Microsoft Academic Search

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

Doug Breden; Kenji Miki; Laxminarayan L. Raja

2011-01-01

229

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

230

[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

231

Computational study of the interaction of cold atmospheric helium plasma jets with surfaces  

NASA Astrophysics Data System (ADS)

We describe a computational modeling study of a cold atmospheric pressure plasma jet interacting with a dielectric surface placed normal to the jet axis. The plasma jet is generated by the application of a nanosecond pulse voltage applied to a dielectric tube through which the jet issues into ambient air. A base fluid flow field is pre-computed using a Navier–Stokes model for the helium jet impinging on the dielectric target surface with a two-species description for laminar diffusional mixing of the helium and ambient air streams. A self-consistent, multiple species, two-temperature model is used to describe the non-equilibrium plasma discharge dynamics in the presence of the base jet flow field. A single nanosecond pulse discharge event starting from initial breakdown in the dielectric tube, to propagation into the open gap, and finally the interaction with the dielectric surface is simulated. Initially, the plasma forms within the dielectric tube and propagates along the tube surface as a surface discharge driven by large induced electric fields produced by trapped charge on the dielectric surface. When the discharge reaches the end of the dielectric tube, the discharge transitions to a constricted fast ionization wave that propagates along the helium–air interface. The fast ionization wave eventually reaches the dielectric target surface where charged species are deposited as the discharge propagates parallel to the wall as a surface driven discharge. The surface driven discharge ceases to propagate once the quantity of air to helium is sufficient enough to quench the hot electrons and prevent further ionization. Due to the low speed of the flow discharge and the short life times of the radical species such as O, most of the radical species delivered to the surface are a result of the surface discharge that forms after the plasma bullet impinges against the surface. It is found that factors such as the thickness of the target dielectric and the profile of the stagnation helium–air jet significantly impact the net quantity of reactive particles delivered to the surface.

Breden, Douglas; Raja, Laxminarayan L.

2014-12-01

232

Heat transport of nitrogen in helium atmospheric pressure microplasma  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

233

Marangoni flows induced by atmospheric-pressure plasma jets  

NASA Astrophysics Data System (ADS)

We studied the interaction of atmospheric-pressure plasma jets of Ar or air with liquid films of an aliphatic hydrocarbon on moving solid substrates. The hydrodynamic jet-liquid interaction induces a track of lower film thickness. The chemical plasma-surface interaction oxidizes the liquid, leading to a local increase of the surface tension and a self-organized redistribution of the liquid film. We developed a numerical model that qualitatively reproduces the formation, instability and coarsening of the flow patterns observed in the experiments. Monitoring the liquid flow has potential as an in-situ, spatially and temporally resolved, diagnostic tool for the plasma-liquid surface interaction.

Berendsen, C. W. J.; van Veldhuizen, E. M.; Kroesen, G. M. W.; Darhuber, A. A.

2015-01-01

234

Microwave generation of stable atmospheric-pressure fireballs in air  

SciTech Connect

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

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

2006-11-15

235

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

2006-11-01

236

A lidar system for measuring atmospheric pressure and temperature profiles  

NASA Technical Reports Server (NTRS)

The design and operation of a differential absorption lidar system capable of remotely measuring the vertical structure of tropospheric pressure and temperature are described. The measurements are based on the absorption by atmospheric oxygen of the spectrally narrowband output of two pulsed alexandrite lasers. Detailed laser output spectral characteristics, which are critical to successful lidar measurements, are presented. Spectral linewidths of 0.026 and 0.018 per cm for the lasers were measured with over 99.99 percent of the energy contained in three longitudinal modes.

Schwemmer, Geary K.; Dombrowski, Mark; Korb, C. Laurence; Milrod, Jeffry; Walden, Harvey

1987-01-01

237

Driven Motion and Instability of an Atmospheric Pressure Arc  

SciTech Connect

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

Max Karasik

1999-12-01

238

Electrical characteristics and formation mechanism of atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

239

Electrode erosion in arc discharges at atmospheric pressure  

NASA Technical Reports Server (NTRS)

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

Hardy, T. L.

1985-01-01

240

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

241

Electrode erosion in arc discharges at atmospheric pressure  

NASA Technical Reports Server (NTRS)

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

Hardy, T. L.

1985-01-01

242

Experimental Investigation Of Atmospheric Pressure Surface Wave Discharges  

SciTech Connect

Microwave atmospheric pressure discharge in neon sustained by surface waves in a dielectric tube is considered. The plasma column length was measured versus absorbed microwave power for different discharge conditions. This gives a view on the wave propagation characteristics. The predicted dependence of discharge length on the total flux of wave power based on the modified model of non-equilibrium plasma is compared with experimental values. Moreover, we present results of spectroscopic investigations of the electron density. The electron density was determined using the method based on the Stark broadening of H{beta} spectral line. The spectroscopic results we shall use developing of a model of propagation of surface wave.

Czylkowski, D.; Jasinski, M.; Nowakowska, H.; Zakrzewski, Z. [The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk (Poland)

2006-01-15

243

Electrical characteristics and formation mechanism of atmospheric pressure plasma jet  

SciTech Connect

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

Liu, Lijuan; Zhang, Yu; Tian, Weijing; Meng, Ying; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

2014-06-16

244

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

245

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

SciTech Connect

An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O{sub 2}/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion, Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China) and School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 137-701 (Korea, Republic of)

2011-10-15

246

Optical and Electrical Measurements in Atmospheric Pressure Arcs: a Comparison  

NASA Astrophysics Data System (ADS)

Atmospheric pressure arcs are investigated by emission spectroscopy and electric exploration techniques. Temperature maps for arc currents in the range 100-200 A show good agreement with previously published data. An extended study on Langmuir probes in arcs has been performed and a multi-wire apparatus was constructed. The probes characteristic curve is distorted at high pressure and as a consistent theory is lacking, interpretation difficulties are outlined. Comparison with temperatures obtained from optical spectroscopy is made in order to correct for 'cooler' probe temperatures. Arc radii in biased and floating conditions are examined and estimates of the axial electric field are presented. Data from carbon diamond partially coated probes suggest a differential charge capture. The investigation of the anode region can be performed using a split-anode' technique and the prototype is described of a modified apparatus, which avoids the two-dimensional Abel inversion needed to reconstruct local information.

Fanara, Carlo; Oliveira Vilarinho, Louriel

2002-10-01

247

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

248

Atmospheric-pressure plasma decontamination/sterilization chamber  

DOEpatents

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

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

2001-01-01

249

Characterization of a steam plasma jet at atmospheric pressure  

NASA Astrophysics Data System (ADS)

An atmospheric steam plasma jet generated by an original dc water plasma torch is investigated using electrical and spectroscopic techniques. Because it directly uses the water used for cooling electrodes as the plasma-forming gas, the water plasma torch has high thermal efficiency and a compact structure. The operational features of the water plasma torch and the generation of the steam plasma jet are analyzed based on the temporal evolution of voltage, current and steam pressure in the arc chamber. The influence of the output characteristics of the power source, the fluctuation of the arc and current intensity on the unsteadiness of the steam plasma jet is studied. The restrike mode is identified as the fluctuation characteristic of the steam arc, which contributes significantly to the instabilities of the steam plasma jet. In addition, the emission spectroscopic technique is employed to diagnose the steam plasma. The axial distributions of plasma parameters in the steam plasma jet, such as gas temperature, excitation temperature and electron number density, are determined by the diatomic molecule OH fitting method, Boltzmann slope method and H? Stark broadening, respectively. The steam plasma jet at atmospheric pressure is found to be close to the local thermodynamic equilibrium (LTE) state by comparing the measured electron density with the threshold value of electron density for the LTE state. Moreover, based on the assumption of LTE, the axial distributions of reactive species in the steam plasma jet are estimated, which indicates that the steam plasma has high chemical activity.

Ni, Guohua; Zhao, Peng; Cheng, Cheng; Song, Ye; Toyoda, Hirotaka; Meng, Yuedong

2012-02-01

250

Inactivation of Escherichia coli using atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure argon (Ar) plasma jet was applied to the inactivation of Escherichia coli. The Ar plasma jet was generated at a frequency of 10 kHz, an applied voltage of 10 kV, and an Ar gas flow rate of 10 L/min at atmospheric pressure. E. coli cells seeded on an agar medium in a Petri dish were inactivated by Ar plasma jet irradiation for 1 s. Scanning electron microscopy (SEM) revealed that E. coli cells were killed because their cell wall and membrane were disrupted. To determine the causes of the disruption of the cell wall and membrane of E. coli, we performed the following experiments: the measurement of the surface temperature of an agar medium using a thermograph, the analysis of an emission spectrum of a plasma jet obtained using a multichannel spectrometer, and the determination of the distribution of the concentration of hydrogen peroxide (H2O2) generated on an agar medium by plasma jet irradiation using semiquantitative test strips. Moreover, H2O2 solutions of different concentrations were dropped onto an agar medium seeded with E. coli cells to examine the contribution of H2O2 to the death of E. coli. The results of these experiments showed that the cell wall and membrane of E. coli were disrupted by electrons in the plasma jet, as well as by electroneutral excited nitrogen molecules (N2) and hydroxyl (OH) radicals in the periphery of the plasma jet.

Kuwahata, Hiroshi; Yamaguchi, Takeshi; Ohyama, Ryu-ichiro; Ito, Atsushi

2015-01-01

251

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

252

Pluto's insolation history: Latitudinal variations and effects on atmospheric pressure  

NASA Astrophysics Data System (ADS)

Since previous long-term insolation modeling in the early 1990s, new atmospheric pressure data, increased computational power, and the upcoming flyby of the Pluto system by NASA's New Horizons spacecraft have generated new motivation and increased capabilities for the study of Pluto's complex long-term (million-years) insolation history. The two primary topics of interest in studying Pluto's insolation history are the variations in insolation patterns when integrated over different intervals and the evolution of diurnal insolation patterns over the last several decades. We find latitudinal dichotomies when comparing average insolation over timescales of days, decades, centuries, and millennia, where all timescales we consider are short relative to the predicted timescales for Pluto's chaotic orbit. Depending on the timescales of volatile migration, some consequences of these insolation patterns may be manifested in the surface features revealed by New Horizons. We find the Maximum Diurnal Insolation (MDI) at any latitude is driven most strongly when Pluto's obliquity creates a long arctic summer (or "midnight sun") beginning just after perihelion. Pluto's atmospheric pressure, as measured through stellar occultation observations during the past three decades, shows a circumstantial correlation with this midnight sun scenario as quantified by the MDI parameter.

Earle, Alissa M.; Binzel, Richard P.

2015-04-01

253

Atmospheric oxygenation caused by a change in volcanic degassing pressure.  

PubMed

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

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

2011-10-13

254

Specific Interaction Between Negative Atmospheric Ions and Organic Compounds in Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O{2/-}, HCO{3/-}, COO-(COOH), NO{2/-}, NO{3/-}, and NO{3/-}(HNO3) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion.

Sekimoto, Kanako; Sakai, Mami; Takayama, Mitsuo

2012-06-01

255

Restoration of Sensitivity in Chemo — Resistant Glioma Cells by Cold Atmospheric Plasma  

PubMed Central

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

2013-01-01

256

Microstreamer dynamics during plasma remediation of NO using atmospheric pressure dielectric barrier discharges  

E-print Network

Microstreamer dynamics during plasma remediation of NO using atmospheric pressure dielectric- ate toxins from atmospheric pressure gas streams. Plasma remediation is one technique which has been methods for the removal of oxides of nitrogen NxOy from atmospheric gas streams and among those techniques

Kushner, Mark

257

Measurement of viscosity of gaseous mixtures at atmospheric pressure  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

258

Atmospheric Dynamics III Fall 20131 The Formation and Movement of Upper-Level Pressure  

E-print Network

Atmospheric Dynamics III Fall 20131 The Formation and Movement of Upper-Level Pressure Systems Introduction: Upper-level pressure systems are pressure systems in the mid-to-upper troposphere. These pressure systems are not significantly influenced by earth's surface friction. Upper-level pressure systems can

Droegemeier, Kelvin K.

259

Three-dimensional gas temperature measurements in atmospheric pressure microdischarges using Raman scattering  

E-print Network

Three-dimensional gas temperature measurements in atmospheric pressure microdischarges using Raman of small dimensions 100 s of micrometers , atmospheric pressure operation, and high power densities 10A discharge. © 2006 American Institute of Physics. DOI: 10.1063/1.2404594 High pressure nonequilibrium

Economou, Demetre J.

260

Response of the Mediterranean mean sea level to atmospheric pressure forcing  

Microsoft Academic Search

The response of the Mediterranean mean sea level to atmospheric pressure forcing is analyzed using 3 years of TOPEX\\/POSEIDON data. Coherence analysis between mean sea level and atmospheric pressure shows a significant departure from a standard inverse barometer effect at frequencies higher than 30days-1. At high frequencies the phase difference between sea level and pressure is about 100°, while it

Pierre-Yves Le Traon; Philippe Gauzelin

1997-01-01

261

Inactivation of a foodborne norovirus outbreak strain with nonthermal atmospheric pressure plasma.  

PubMed

Human norovirus (NoV) is the most frequent cause of epidemic nonbacterial acute gastroenteritis worldwide. We investigated the impact of nonthermal or cold atmospheric pressure plasma (CAPP) on the inactivation of a clinical human outbreak NoV, GII.4. Three different dilutions of a NoV-positive stool sample were prepared and subsequently treated with CAPP for various lengths of time, up to 15 min. NoV viral loads were quantified by quantitative real-time reverse transcription PCR (RT-qPCR). Increased CAPP treatment time led to increased NoV reduction; samples treated for the longest time had the lowest viral load. From the initial starting quantity of 2.36 × 10(4) genomic equivalents/ml, sample exposure to CAPP reduced this value by 1.23 log10 and 1.69 log10 genomic equivalents/ml after 10 and 15 min, respectively (P < 0.01). CAPP treatment of surfaces carrying a lower viral load reduced NoV by at least 1 log10 after CAPP exposure for 2 min (P < 0.05) and 1 min (P < 0.05), respectively. Our results suggest that NoV can be inactivated by CAPP treatment. The lack of cell culture assays prevents our ability to estimate infectivity. It is possible that some detectable, intact virus particles were rendered noninfectious. We conclude that CAPP treatment of surfaces may be a useful strategy to reduce the risk of NoV transmission in crowded environments. IMPORTANCE?: Human gastroenteritis is most frequently caused by noroviruses, which are spread person to person and via surfaces, often in facilities with crowds of people. Disinfection of surfaces that come into contact with infected humans is critical for the prevention of cross-contamination and further transmission of the virus. However, effective disinfection cannot be done easily in mass catering environments or health care facilities. We evaluated the efficacy of cold atmospheric pressure plasma, an innovative airborne disinfection method, on surfaces inoculated with norovirus. We used a clinically relevant strain of norovirus from an outbreak in Germany. Cold plasma was able to inactivate the virus on the tested surfaces, suggesting that this method could be used for continuous disinfection of contaminated surfaces. The use of a clinical strain of norovirus strengthens the reliability of our results as it is a strain relevant to outbreaks in humans. PMID:25587014

Ahlfeld, Birte; Li, Yangfang; Boulaaba, Annika; Binder, Alfred; Schotte, Ulrich; Zimmermann, Julia L; Morfill, Gregor; Klein, Günter

2015-01-01

262

Inactivation of a Foodborne Norovirus Outbreak Strain with Nonthermal Atmospheric Pressure Plasma  

PubMed Central

ABSTRACT? Human norovirus (NoV) is the most frequent cause of epidemic nonbacterial acute gastroenteritis worldwide. We investigated the impact of nonthermal or cold atmospheric pressure plasma (CAPP) on the inactivation of a clinical human outbreak NoV, GII.4. Three different dilutions of a NoV-positive stool sample were prepared and subsequently treated with CAPP for various lengths of time, up to 15 min. NoV viral loads were quantified by quantitative real-time reverse transcription PCR (RT-qPCR). Increased CAPP treatment time led to increased NoV reduction; samples treated for the longest time had the lowest viral load. From the initial starting quantity of 2.36 × 104 genomic equivalents/ml, sample exposure to CAPP reduced this value by 1.23 log10 and 1.69 log10 genomic equivalents/ml after 10 and 15 min, respectively (P < 0.01). CAPP treatment of surfaces carrying a lower viral load reduced NoV by at least 1 log10 after CAPP exposure for 2 min (P < 0.05) and 1 min (P < 0.05), respectively. Our results suggest that NoV can be inactivated by CAPP treatment. The lack of cell culture assays prevents our ability to estimate infectivity. It is possible that some detectable, intact virus particles were rendered noninfectious. We conclude that CAPP treatment of surfaces may be a useful strategy to reduce the risk of NoV transmission in crowded environments. Importance? Human gastroenteritis is most frequently caused by noroviruses, which are spread person to person and via surfaces, often in facilities with crowds of people. Disinfection of surfaces that come into contact with infected humans is critical for the prevention of cross-contamination and further transmission of the virus. However, effective disinfection cannot be done easily in mass catering environments or health care facilities. We evaluated the efficacy of cold atmospheric pressure plasma, an innovative airborne disinfection method, on surfaces inoculated with norovirus. We used a clinically relevant strain of norovirus from an outbreak in Germany. Cold plasma was able to inactivate the virus on the tested surfaces, suggesting that this method could be used for continuous disinfection of contaminated surfaces. The use of a clinical strain of norovirus strengthens the reliability of our results as it is a strain relevant to outbreaks in humans. PMID:25587014

Ahlfeld, Birte; Li, Yangfang; Boulaaba, Annika; Binder, Alfred; Schotte, Ulrich; Zimmermann, Julia L.; Morfill, Gregor

2015-01-01

263

Controlling the NO production of an atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

The production of NO radicals by an atmospheric pressure plasma jet has been investigated by means of absorption spectroscopy in the mid-infrared region (IR) and optical emission spectroscopy (OES) in the ultraviolet (UV) part of the spectrum. The plasma jet investigated here operates in argon with air admixtures up to 1%. The study shows that OES can be used to characterize the relative NO production at small air admixtures. The Production of NO radicals can be controlled by variation of air admixture. Important to note—especially for operation in ambient conditions—is that a small addition of water vapour strongly affects the production of NO radicals especially at higher air admixtures (greater than 0.2%).

Pipa, A. V.; Reuter, S.; Foest, R.; Weltmann, K.-D.

2012-02-01

264

Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry of Carotenoids  

PubMed Central

Carotenoids are natural pigments synthesized by plants and photosynthetic microorganisms, some of which, like ?-carotene, are precursors of vitamin A, and others such as lutein and lycopene might function in the prevention of age-related macular degeneration and prostate cancer, respectively. Mass spectrometry provides high sensitivity and selectivity for the identification and quantitative analysis of carotenoids in biological samples, and previous studies have described how atmospheric pressure chemical ionization (APCI) offers distinct advantages over electrospray and fast atom bombardment for the analysis of specific carotenoids. Since APCI product ion tandem mass spectra have been reported for only a few carotenoids, a detailed investigation of twelve carotenes and xanthophylls was carried out using both positive ion and negative ion APCI tandem mass spectrometry with collision-induced dissociation. Using protonated molecules as precursor ions in positive ion mode and radical anions in negative ion mode, characteristic fragment ions were identified that may be used to distinguish between carotenoids. PMID:22408388

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

2011-01-01

265

Efficacy of Nonthermal Atmospheric Pressure Plasma for Tooth Bleaching  

PubMed Central

The conventional light source used for tooth bleaching has the potential to cause thermal damage, and the actual role of the light source is doubtful. In this study, we evaluated bleaching efficacy, temperature, and morphological safety after tooth bleaching with nonthermal atmospheric pressure plasma. Tooth bleaching combined with plasma had improved efficacy in providing a higher level of brightness. The temperature of the pulp chamber was maintained around 37°C, indicating that the plasma does not cause any thermal damage. The morphological results of tooth bleaching with plasma did not affect mineral composition under scanning electron microscopy (SEM) observations. On the basis of these results, the application of plasma and low concentration of 15% carbamide peroxide (CP) has a high capability for effective tooth bleaching. It can be documented that plasma is a safe energe source, which has no deleterious effects on the tooth surface.

Nam, Seoul Hee; Lee, Hae June; Hong, Jin Woo; Kim, Gyoo Cheon

2015-01-01

266

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

267

Development of ac corona discharge modes at atmospheric pressure  

NASA Astrophysics Data System (ADS)

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

El-Koramy, Reda Ahmed; Yehia, Ashraf; Omer, Mohamed

2011-02-01

268

Decomposition of Glycerine by Water Plasmas at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

High concentration of aqueous glycerine was decomposed using a direct current (DC) plasma torch at atmospheric pressure. The torch can generate the plasma with water as the plasma-supporting gas in the absence of any additional gas supply system and cooling devices. The results indicated that 5 mol% glycerine was completely decomposed by water plasmas at arc powers of 0.55~1.05 kW. The major products in the effluent gas were H2 (68.9%~71.1%), CO2 (18.9%~23.0%), and CO (0.2%~0.6%). However, trace levels of formic acid (HCOOH) and formaldehyde (HCHO) were observed in the liquid effluent. The results indicated that the water plasma waste treatment process is capable of being an alternative green technology for organic waste decomposition.

Takayuki, Watanabe; Narengerile

2013-04-01

269

Determination of hexabromocyclododecane by flowing atmospheric pressure afterglow mass spectrometry.  

PubMed

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

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

2014-10-01

270

Radio jet refraction in galactic atmospheres with static pressure gradients  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

271

Phenomena of oscillations in atmospheric pressure direct current glow discharges  

SciTech Connect

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

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

2013-12-15

272

Development of ac corona discharge modes at atmospheric pressure  

SciTech Connect

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

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

2011-02-15

273

Electron Density in Atmospheric Pressure Microwave Surface Wave Discharges  

SciTech Connect

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

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

2008-03-19

274

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

275

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

276

Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma  

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

277

Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

278

Abatement of perfluorocompounds with microwave plasma in atmospheric pressure environment.  

PubMed

Perfluorocompounds emitted by the semiconductor industry are global warming gases. These gases need to be removed efficiently because of their strong absorption of infrared radiation and long atmospheric lifetimes which cause the global warming effect. In this study, microwave argon plasma operating at atmospheric pressure was investigated experimentally for various operating conditions including microwave power, total gas flow rate, initial concentration, and additive gas. The mechanisms of perfluorocompounds decomposition were studied by the plasma emission spectrum. Under the optimum condition, the destruction and removal efficiency of CF(4) could reach up to 98.4%. The emission spectrum analysis indicated that the existence of the O or OH radicals could enhance the CF(4) decomposition by adding suitable volume of O(2) or H(2)O. The mechanisms of CF(4) decomposition are that the electron, O and OH radicals all associated with CF(4) conversion, it has the sequence that enough effective electrons reacted with CF(4) to form CF(i) radicals, O and OH radicals further reacted with CF(i) radicals to convert CF(4) into CO(2) and HF. PMID:19362773

Xie, Hongduan; Sun, Bing; Zhu, Xiaomei

2009-09-15

279

Effects of gravity and pressure on laminar coflow methaneair diffusion flames at pressures from 1 to 60 atmospheres  

E-print Network

Effects of gravity and pressure on laminar coflow methane­air diffusion flames at pressures from 1 to 60 atmospheres Marc R.J. Charest , Clinton P.T. Groth, �mer L. Gülder University of Toronto January 2011 Available online 12 February 2011 Keywords: High pressure combustion Zero-gravity combustion

Groth, Clinton P. T.

280

Temporal and spectral characteristics of atmospheric pressure argon plasma jet  

NASA Astrophysics Data System (ADS)

An investigation of atmospheric pressure argon DBD plasma jet generated at 6 kHz sinusoidal voltage was carried out. On the basis of recorded electrical, optical and spectral characteristics spatiotemporal evolution of plasma jet in negative and positive half-cycles of voltage was studied. It was found that the dynamics of argon jet propagation outside the tube differs considerably from that found by other authors in the case of helium jet. The difference was explained with the influence of Penning reactions between metastable state He atoms and air molecules in He jet. On the basis of radiative transitions N2 (C-B, 0-0) and OH(A-X, 0-0) the rotational temperatures of N2(C, 0) and OH(A, 0) were estimated along jet axis. In regions where Ar-air mixing was negligible or low, the rotational temperatures of both molecules coincide and were close to the gas temperature. 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.

Raud, Jüri; Jõgi, Indrek; Laan, Matti; Laast, Marti

2013-02-01

281

Measurements of streamer head potential and conductivity of streamer column in the cold nonequilibrium atmospheric plasmas  

PubMed Central

This work presents a simple method for the characterization of streamers developing in cold atmospheric plasma jets. The method is based upon stopping (“scattering”) of streamer by means of external DC potential in order to determine the potential of the streamer head. The experimental evidence presented in this work does not support the model of the electrically insulated streamer head. On the contrary, it is shown that the electrode potential is transferred to the streamer head along the streamer column to which it is attached with no significant voltage drop. Based on the proposed method, we determine various streamer parameters such as head charge (1–2×108 electrons), electrical field in the head vicinity (about 100 kV/cm), average conductivity (10?2 ??1cm?1) and plasma density of the streamer column (2×1013 cm?3). PMID:25642104

Shashurin, A.; Shneider, M. N.; Keidar, M.

2015-01-01

282

The effects of atmospheric pressure on infrared reflectance spectra of Martian analogs  

NASA Technical Reports Server (NTRS)

The use of terrestrial samples as analogs of Mars soils are complicated by the Martian atmosphere. Spectral features due to the Martian atmosphere can be removed from telescopic spectra of Mars and ISM spectra of Mars, but this does not account for any spectral differences resulting from atmospheric pressure or any interactions between the atmosphere and the surface. We are examining the effects of atmospheric pressure on reflectance spectra of powdered samples in the laboratory. Contrary to a previous experiment with granite, no significant changes in albedo or the Christiansen feature were observed from 1 bar pressure down to a pressure of 8 micrometers Hg. However, reducing the atmospheric pressure does have a pronounced affect on the hydration features, even for samples retained in a dry environment for years.

Bishop, Janice L.; Pieters, Carle M.; Pratt, Stephen F.; Patterson, William

1993-01-01

283

The effects of atmospheric pressure on infrared reflectance spectra of Martian analogs  

NASA Astrophysics Data System (ADS)

The use of terrestrial samples as analogs of Mars soils are complicated by the Martian atmosphere. Spectral features due to the Martian atmosphere can be removed from telescopic spectra of Mars and ISM spectra of Mars, but this does not account for any spectral differences resulting from atmospheric pressure or any interactions between the atmosphere and the surface. We are examining the effects of atmospheric pressure on reflectance spectra of powdered samples in the laboratory. Contrary to a previous experiment with granite, no significant changes in albedo or the Christiansen feature were observed from 1 bar pressure down to a pressure of 8 micrometers Hg. However, reducing the atmospheric pressure does have a pronounced affect on the hydration features, even for samples retained in a dry environment for years.

Bishop, Janice L.; Pieters, Carle M.; Pratt, Stephen F.; Patterson, William

1993-03-01

284

The Effect of Cold Climate upon North Atlantic Deep Water Formation in a Simple Ocean-Atmosphere Model  

Microsoft Academic Search

The sensitivity of North Atlantic Deep Water formation to variations in mean surface temperature is explored with a meridional-vertical plane ocean model coupled to an energy balance atmosphere. It is found that North Atlantic Deep Water formation is favored by a warm climate, while cold climates are more likely to produce Southern Ocean deep water or deep-decoupling oscillations (when the

Michael Winton

1997-01-01

285

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

286

The emissions of gases from abandoned mines: role of atmospheric pressure changes and air temperature on the surface  

E-print Network

1 The emissions of gases from abandoned mines: role of atmospheric pressure changes and air . Atmospheric pressure . Air temperature on the surface . Exits . Open or closed old mining voids Introduction, atmospheric pressure, speed and direction of the wind have also effects on mine gas outflow or atmospheric gas

Boyer, Edmond

287

Surface Treatment of Polyethylene Terephthalate Film Using Atmospheric Pressure Glow Discharge in Air  

Microsoft Academic Search

Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of

Zhi Fang; Yuchang Qiu; Hui Wang

2004-01-01

288

Comparison of Dielectric Barrier Discharge and Atmospheric Pressure Glow Discharge for Surface Modification of PET Film  

Microsoft Academic Search

Non-equilibrium plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In the present work polyethylene terephthalate (PET) film surface is modified using the non-equilibrium plasma generated by the atmospheric pressure glow discharge (APGD) and dielectric barrier discharge (DBD) in ambient air. The differences in discharge characteristics between APGD and

Zhi Fang; Yuchang Qiu; Edmund Kuffel

2007-01-01

289

Abstract The present study uses increased atmospheric pressure as an ethanol antagonist to test the hypothesis  

E-print Network

Abstract The present study uses increased atmospheric pressure as an ethanol antagonist to test of pressure on ethanol and other GABAergic drugs in C57BL/6 and LS mice. Be- haviorally, exposure to 12 times normal atmospheric pres- sure (ATA) of a helium-oxygen gas mixture (heliox) an- tagonized loss

Brinton, Roberta Diaz

290

Liquid chromatography\\/atmospheric pressure ionization-mass spectrometry in drug metabolism studies  

Microsoft Academic Search

Thestudyofthemetabolicfateofdrugs isanessentialand importantpartofthedrug developmentprocess. The analysis of metabolites is a challenging task and several different analytical methods have been used in these studies. However, after the introduction of the atmospheric pressure ionization (API) technique, electrospray and atmospheric pressure chemical ionization, liquid chromatography\\/mass spectrometry (LC\\/MS) has become an important and widely used method in the analysis of metabolites owing to its

R. Kostiainen; T. Kotiaho; T. Kuuranne; S. Auriola

2003-01-01

291

Spectroscopy of atmospheric pressure air jet plasma in transverse arc discharge Valeriy Chernyak1  

E-print Network

Spectroscopy of atmospheric pressure air jet plasma in transverse arc discharge Valeriy Chernyak1 of the atmospheric pressure air jet plasma in the transverse cw dc arc discharge of high voltage was done. Within discharge air plasma during its space/time evolution, and effects of strong non-izothermality have a place

Paris-Sud XI, Université de

292

Atmospheric pressure plasma jets beyond ground electrode as charge overflow in a dielectric barrier discharge setup  

E-print Network

Atmospheric pressure plasma jets beyond ground electrode as charge overflow in a dielectric barrier voltage and the width of ground electrode, atmospheric pressure plasma jets extending beyond the ground, that surprisingly a plasma jet in the ambient air can penetrate the wall of a dielectric tube, and a secondary

Zexian, Cao

293

EDITORIAL: Atmospheric pressure non-thermal plasmas for processing and other applications  

Microsoft Academic Search

Interest has grown over the past few years in applying atmospheric pressure plasmas to plasma processing for the benefits this can offer to existing and potential new processes, because they do not require expensive vacuum systems and batch processing. There have been considerable efforts to efficiently generate large volumes of homogeneous atmospheric pressure non-thermal plasmas to develop environmentally friendly alternatives

Françoise Massines

2005-01-01

294

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. PMID:22558091

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

2012-01-01

295

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

296

Growth of silicon oxynitride films by atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

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

Zhang, Xueqiang; Ptasinska, Sylwia

2014-04-01

297

Water solubility in rhyolitic silicate melts at atmospheric pressure  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

298

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

299

Pressure Sounding of the Middle Atmosphere from ATMOS Solar Occultation Measurements of Atmospheric CO(sub 2) Absorption Lines  

NASA Technical Reports Server (NTRS)

A method for retrieving the atmospheric pressure corresponding to the tangent point of an infrared spectrum recorded in the solar occultation mode is described and applied to measurements made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer. Tangent pressure values are inferred from measurements of isolated CO(sub 2) lines with temperature-insensitive intensities. Tangent pressures are determined with a spectroscopic precision of 1-3%, corresponding to a tangent point height precision, depending on the scale height, of 70-210 meters.

Abrams, M.; Gunson, M.; Lowes, L.; Rinsland, C.; Zander, R.

1994-01-01

300

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

301

Effect of heat, cold, and pressure on the transverse carpal ligament and median nerve: a pilot study.  

PubMed

Background This study quantified the effects of heat, cold, and pressure on the median nerve and transverse carpal ligament in subjects without carpal tunnel syndrome. Material and Methods Subjects were individuals ages 20-50 who had no symptoms of carpal tunnel disease. Imaging ultrasound was used to measure the clearance around the median nerve, transverse ligament elasticity, nerve conduction velocity, thickness of the carpal ligament, and area of the median nerve. Pressure was applied to the carpal ligament to assess the effects of increasing pressure on these structures. On 3 separate days, 10 subjects had ThermaCare heat or cold packs applied, for either 60 or 120 minutes for heat or 20 minutes for cold, to the palmer surface of the hand. Results Tissue changes were recorded as a response to pressure applied at 0, 5, 10, and 20 N. The size of the nerve and ligaments were not significantly altered by pressure with the hand at room temperature and after cold exposure. After heat, the nerve, ligaments, and tendons showed significantly more elasticity. Conclusions Application of cold to the hand may reduce compression of the carpal ligament and nerve. PMID:25669437

Laymon, Michael; Petrofsky, Jerrold; McKivigan, James; Lee, Haneul; Yim, JongEun

2015-01-01

302

Cold acclimation increases cardiac myofilament function and ventricular pressure generation in trout.  

PubMed

Reducing temperature below the optimum of most vertebrate hearts impairs contractility and reduces organ function. However, a number of fish species, including the rainbow trout, can seasonally acclimate to low temperature. Such ability requires modification of physiological systems to compensate for the thermodynamic effects of temperature on biological processes. The current study tested the hypothesis that rainbow trout compensate for the direct effect of cold temperature by increasing cardiac contractility during cold acclimation. We examined cardiac contractility, following thermal acclimation (4, 11 and 17°C), by measuring the Ca(2+) sensitivity of force generation by chemically skinned cardiac trabeculae as well as ventricular pressure generation using a modified Langendorff preparation. We demonstrate, for the first time, that the Ca(2+) sensitivity of force generation was significantly higher in cardiac trabeculae from 4°C-acclimated trout compared with those acclimated to 11 or 17°C, and that this functional change occurred in parallel with a decrease in the level of cardiac troponin T phosphorylation. In addition, we show that the magnitude and rate of ventricular pressure generation was greater in hearts from trout acclimated to 4°C compared with those from animals acclimated to 11 or 17°C. Taken together, these results suggest that enhanced myofilament function, caused by modification of existing contractile proteins, is at least partially responsible for the observed increase in pressure generation after acclimation to 4°C. In addition, by examining the phenotypic plasticity of a comparative model we have identified a strategy, used in vivo, by which the force-generating capacity of cardiac muscle can be increased. PMID:25278471

Klaiman, Jordan M; Pyle, W Glen; Gillis, Todd E

2014-12-01

303

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

304

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

NASA Astrophysics Data System (ADS)

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

Liu, Yaoge; Hao, Yanpeng; Zheng, Bin

2012-09-01

305

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

306

Atmospheric pressure photoionization mass spectrometry of polyisobutylene derivatives.  

PubMed

Atmospheric pressure photoionization mass spectrometric (APPI-MS) study on three types of polyisobutylene derivatives is reported. Two of the polyisobutylenes investigated were polyisobutylene with dihydroxy and diolefinic end-groups derived from aromatic moieties [dicumyl chloride, 1,4-bis(2-chloro-2-propyl)benzene], and the third contained no aromatic moieties with a monohydroxy end-group. All three polyisobutylene derivatives (PIBs) had an average molecular weight (M(n)) of approximately 2000 g/mol, with a polydispersity lower than 1.2. In the positive ion APPI mode, protonated PIB molecules were formed, but the molecular weights obtained were considerably lower than those expected, indicating fragmentation of the PIB chains. In the negative APPI mode, using solvents such as tetrahydrofuran and toluene as dopants, no signal was obtained. However, in chlorinated solvents, such as CCl(4), CHCl(3), and CH(2)Cl(2), in the presence of toluene dopant, PIB adducts with chloride ions were formed with relatively high signal intensity. In the case of CH(2)Cl(2), no dopant (toluene) was necessary to generate chlorinated adduct ions, albeit increasing the toluene concentration in the flow increased the PIB signal intensity. The effect of the toluene concentration on PIB signal intensity was studied and models that include (1) photoionization of toluene, (2) formation of chloride ions from the chlorinated solvents by dissociative electron capture, (3) formation of chlorinated adduct ions and charge recombination reactions between the toluene radical cation, (4) chloride ions, and (5) chlorinated adduct ions are proposed based on the experimental results. PMID:18356077

Kéki, Sándor; Török, János; Nagy, Lajos; Zsuga, Miklós

2008-05-01

307

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

308

Atmospheric Dynamics III Fall 20131 The Formation and Movement of Surface Pressure Systems  

E-print Network

Atmospheric Dynamics III Fall 20131 The Formation and Movement of Surface Pressure Systems Introduction: It makes sense that low-pressure systems would move towards areas of lower geopotential height-tendency, and high-pressure systems would move towards areas of higher geopotential height-tendency, so this is why

Droegemeier, Kelvin K.

309

Characterization of Pt/SiO2 Model Catalysts at UHV and Near Atmospheric Pressures  

E-print Network

Characterization of Pt/SiO2 Model Catalysts at UHV and Near Atmospheric Pressures Sean M. Mc catalyst samples, prepared under UHV conditions in a contiguous high pressure reactor cell surface analysis chamber, have been characterized via CO oxidation reaction kinetics under elevated pressure condi- tions

Goodman, Wayne

310

Atmospheric cold plasma inactivation of aerobic microorganisms on blueberries and effects on quality attributes.  

PubMed

Cold plasma (CP) is a novel nonthermal technology, potentially useful in food processing settings. Berries were treated with atmospheric CP for 0, 15, 30, 45, 60, 90, or 120 s at a working distance of 7.5 cm with a mixture of 4 cubic feet/minute (cfm) of CP jet and 7 cfm of ambient air. Blueberries were sampled for total aerobic plate count (APC) and yeast/molds immediately after treatment and at 1, 2, and 7 days. Blueberries were also analyzed for compression firmness, surface color, and total anthocyanins immediately after each treatment. All treatments with CP significantly (P < 0.05) reduced APC after exposure, with reductions ranging from 0.8 to 1.6 log CFU/g and 1.5 to 2.0 log CFU/g compared to the control after 1 and 7 days, respectively. Treatments longer than 60s resulted in significant reductions in firmness, although it was demonstrated that collisions between the berries and the container contributed significantly to softening. A significant reduction in anthocyanins was observed after 90 s. The surface color measurements were significantly impacted after 120 s for the L* and a* values and 45 s for the b* values. CP can inactivate microorganisms on blueberries and could be optimized to improve the safety and quality of produce. PMID:25475318

Lacombe, Alison; Niemira, Brendan A; Gurtler, Joshua B; Fan, Xuetong; Sites, Joseph; Boyd, Glenn; Chen, Haiqiang

2015-04-01

311

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

2013-04-30

312

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

313

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

314

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

SciTech Connect

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 CO{sub 2} 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. [Thermophysical Properties Division National Institute of Standards and Technology, Boulder, Colorado (United States)] [Thermophysical Properties Division National Institute of Standards and Technology, Boulder, Colorado (United States); McLinden, M. O. [Thermophysical Properties Division, National Institute of Standards and Technology, Boulder, Colorado (United States)] [Thermophysical Properties Division, National Institute of Standards and Technology, Boulder, Colorado (United States); Tew, W. L. [Sensor Science Division National Institute of Standards and Technology, Gaithersburg, Maryland (United States)] [Sensor Science Division National Institute of Standards and Technology, Gaithersburg, Maryland (United States)

2013-09-11

315

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

316

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

SciTech Connect

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

Jeffrey Hopwood

2011-05-31

317

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

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

318

Inhibition of Aspergillus flavus on agar media and brown rice cereal bars using cold atmospheric plasma treatment.  

PubMed

This study aimed to optimize the operating parameters of cold atmospheric plasma treatment to inhibit the growth of Aspergillus flavus on agar media and brown rice cereal bars. The effects of argon plasma jet treatment on the growth of A. flavus on malt extract agar (MEA) at powers of 20 W and 40 W with exposure times at 5, 15 and 25 min were studied using response surface methodology (RSM) with a central composite face-centered (CCF) design. Multiple regression analysis indicated that plasma treatment at 40 W for 25 min is most effective for inhibiting growth of A. flavus on the agar medium. On brown rice cereal bars, plasma powered at 40 W for 20 min was capable of giving protection against A. flavus growth for up to 20 days under storage conditions of 25°C and 100% RH. These results demonstrated the potential of cold atmospheric plasma jet treatment to control mold growth on various food products. PMID:23279819

Suhem, Kitiya; Matan, Narumol; Nisoa, Mudtorlep; Matan, Nirundorn

2013-02-01

319

Diamond and Related Materials, 2 (1993) 661 666 661 Degenerate four-wave mixing diagnostics of atmospheric pressure  

E-print Network

of atmospheric pressure diamond deposition T. G. Owano and C. H. Kruger Iti~'4h7~,mperatureGasdynamies Laboratory of atmospheric pressure diamond synthesis reactors are evaluated. Benefits and disadvantages of optical emission (DFWM), are discussed in terms of their applicability to the harsh environment of atmospheric pressure

Zare, Richard N.

320

Picosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3  

E-print Network

Picosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3 u occurring dur- ing the positive streamer propagation in atmospheric pressure air is presented. It is shown and motivation Streamer in atmospheric pressure air is a contracted ionizing wave that propagates into a low

Boyer, Edmond

321

Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures  

E-print Network

in argon gas at atmospheric pressures Alexander Miloshevsky, Sivanandan S. Harilal, Gennady Miloshevsky formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures. VC plasma expansion into a background gas at atmospheric pressure is cru- cial for many engineering

Harilal, S. S.

322

Modeling the barotropic response of the global ocean to atmospheric wind and pressure forcing -comparisons with observations  

E-print Network

Modeling the barotropic response of the global ocean to atmospheric wind and pressure forcing] A global simulation of the ocean response to atmospheric wind and pressure forcing has been run during the barotropic response of the global ocean to atmospheric wind and pressure forcing - comparisons

323

Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure  

E-print Network

in air at atmospheric pressure David Z. Pai,a Deanna A. Lacoste, and Christophe O. Laux Laboratoire EM2C January 2010; published online 6 May 2010 In atmospheric pressure air preheated from 300 to 1000 K.1063/1.3309758 I. INTRODUCTION Atmospheric pressure air plasmas have potential appli- cations in biomedical

Boyer, Edmond

324

Sub-nanosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3  

E-print Network

Sub-nanosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3 u propagation in atmospheric pressure air is presented. With tens-of-picoseconds and tens-of-microns precision by streamer-head electrons. 1 Introduction Streamer in atmospheric pressure air is a contracted ionizing wave

Boyer, Edmond

325

Effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous carbon films prepared  

E-print Network

Effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties the effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties in various atmospheres such as nitrogen and argon at different chamber pressures. We used Raman spectroscopy

Wei, Qiuming

326

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

327

Driven motion and instability of an atmospheric pressure arc  

NASA Astrophysics Data System (ADS)

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

Karasik, Max

328

Plasma-assisted preparation of Ni\\/SiO 2 catalyst using atmospheric high frequency cold plasma jet  

Microsoft Academic Search

A novel plasma-assisted calcination and reduction (PC&R) method was employed to prepare novel Ni\\/SiO2 catalyst for methane reforming reaction. In the novel process, the precursor was first activated by atmospheric high frequency cold plasma jet for 10min after drying in air, instead of long-time conventional calcination and thermal reduction. The novel catalyst prepared by this way exhibited an improved low-temperature

Gaihuan Liu; Yuliang Li; Wei Chu; Xinyu Shi; Xiaoyan Dai; Yongxiang Yin

2008-01-01

329

Using weather data from the internet to study how atmospheric pressure varies with altitude  

NASA Astrophysics Data System (ADS)

This article presents a simple and motivating activity for schools and colleges that is based on active learning and the use of new technologies to study the variation in atmospheric pressure with height at the lowest altitudes. Students can learn how barometric pressure decreases with height by plotting the atmospheric pressure versus altitude using data obtained from the internet. Using similar methods to those of scientific researchers, the students can learn a practical rule to correct barometric pressure data with altitude, something that is usually expressed at sea level in weather maps.

Moya, A. A.

2014-11-01

330

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

331

Large-Area Organosilicon Film Deposition Using Cyclonic Atmospheric Pressure Glow Discharge  

NASA Astrophysics Data System (ADS)

Cyclonic atmospheric pressure plasma is developed for chamberless deposition of organosilicon thin films from argon/hexamethyldisoxane (HMDSO) mixtures. The surface properties of the resulting plasma films were investigated as a function of RF plasma power. Film characterization was performed by static contact angle measurement, scanning electron microscopy (SEM), atomic forced microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). It was found the RF plasma power is the key factor that to affects the film growth in the atmospheric pressure plasma chemical vapor deposition process. SEM and AFM results indicated that a smooth, continuous, and uniform surface of organosilicon thin films can be formed at a relatively low plasma power input. XPS indicated that atmospheric-pressure plasma-deposited organosilicon films present mainly inorganic characteristics. This study shows a potential of chamberless film growth at atmospheric pressure to form organosilicon thin films for large-area deposition.

Lin, Jin-He; Tsai, Ching-Yuan; Liu, Wei-Ting; Syu, Yu-Kai; Huang, Chun

2013-05-01

332

The Surface-Pressure Signature of Atmospheric Tides in Modern Climate Models  

E-print Network

Although atmospheric tides driven by solar heating are readily detectable at the earth’s surface as variations in air pressure, their simulations in current coupled global climate models have not been fully examined. This ...

Covey, Curt

333

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...

334

Video Article Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure  

E-print Network

Video Article Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure Bindesh the detailed protocol for single cell analysis using LAESI-MS. The presented video demonstrates the analysis

Vertes, Akos

335

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

336

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

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

337

Cold atmospheric plasma, a new strategy to induce senescence in melanoma cells.  

PubMed

Over the past few years, the application of cold atmospheric plasma (CAP) in medicine has developed into an innovative field of research of rapidly growing importance. One promising new medical application of CAP is cancer treatment. Different studies revealed that CAP may potentially affect the cell cycle and cause cell apoptosis or necrosis in tumor cells dependent on the CAP device and doses. In this study, we used a novel hand-held and battery-operated CAP device utilizing the surface micro discharge (SMD) technology for plasma production in air and consequently analysed dose-dependent CAP treatment effects on melanoma cells. After 2 min of CAP treatment, we observed irreversible cell inactivation. Phospho-H2AX immunofluorescence staining and Flow cytometric analysis demonstrated that 2 min of CAP treatment induces DNA damage, promotes induction of Sub-G1 phase and strongly increases apoptosis. Further, protein array technology revealed induction of pro-apoptotic events like p53 and Rad17 phosphorylation of Cytochrome c release and activation of Caspase-3. Interestingly, using lower CAP doses with 1 min of treatment, almost no apoptosis was observed but long-term inhibition of proliferation. H3K9 immunofluorescence, SA-ß-Gal staining and p21 expression revealed that especially these low CAP doses induce senescence in melanoma cells. In summary, we observed differences in induction of apoptosis or senescence of tumor cells in respond to different CAP doses using a new CAP device. The mechanism of senescence with regard to plasma therapy was so far not described previously and is of great importance for therapeutic application of CAP. PMID:23528215

Arndt, Stephanie; Wacker, Eva; Li, Yang-Fang; Shimizu, Tetsuji; Thomas, Hubertus M; Morfill, Gregor E; Karrer, Sigrid; Zimmermann, Julia L; Bosserhoff, Anja-Katrin

2013-04-01

338

Atmospheric pressure-forced subinertial variations in the transport through the Korea Strait  

Microsoft Academic Search

Transport variations with periods of 3 ? 5 days have been measured in the Korea (Tsushima) Strait by cross-strait cable voltage fluctuations and by direct, long-term measurement. Here we show that these variations can be explained in part by large-scale atmospheric pressure fluctuations over the East (Japan) Sea. First, using basin-wide averages of atmospheric pressure and sea surface height we

Sang Jin Lyu; Kuh Kim; Henry T. Perkins

2002-01-01

339

Atmospheric pressure-forced subinertial variations in the transport through the Korea Strait  

Microsoft Academic Search

Transport variations with periods of 3 ~ 5 days have been measured in the Korea (Tsushima) Strait by cross-strait cable voltage fluctuations and by direct, long-term measurement. Here we show that these variations can be explained in part by large-scale atmospheric pressure fluctuations over the East (Japan) Sea. First, using basin-wide averages of atmospheric pressure and sea surface height we

Sang Jin Lyu; Kuh Kim; Henry T. Perkins

2002-01-01

340

Organic–inorganic behaviour of HMDSO films plasma-polymerized at atmospheric pressure  

Microsoft Academic Search

Recently, plasma-polymerization at atmospheric pressure has become a promising technology due to its reduced equipment costs and its possibility of in-line processing. This paper focuses on plasma deposition by an atmospheric pressure dielectric barrier discharge (DBD) using hexamethyldisiloxane (HMDSO) as gaseous precursor. HMDSO plasma-polymerized films are deposited onto polyethylene terephthalate (PET) films using argon and different argon\\/air mixtures as carrier

Rino Morent; Nathalie De Geyter; Sandra Van Vlierberghe; Peter Dubruel; Christophe Leys; Etienne Schacht

2009-01-01

341

Nanosecond Repetitively Pulsed Discharge of Point–Plane Gaps in Air at Atmospheric Pressure  

Microsoft Academic Search

Atmospheric-pressure gas discharge excited by high- voltage pulses with fast rise time and short duration has at- tracted significant attention for various applications. In this paper, discharges are generated in a highly nonuniform electric field by point-plane gaps in air at atmospheric pressure by a solid-state repetitive nanosecond-pulse generator. Under different experimental conditions, the applied voltage, discharge current, and discharge

Tao Shao; Cheng Zhang; Hui Jiang; Zheng Niu; Ping Yan; Yuanxiang Zhou

2011-01-01

342

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

Microsoft Academic Search

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

Bruce A. Thomson

1998-01-01

343

Effect of washing on surface free energy of polystyrene plate treated by RF atmospheric pressure plasma  

Microsoft Academic Search

Low-temperature plasma can be generated at one atmospheric pressure by applying a radio frequency (RF, 13.56MHz) voltage between two parallel electrodes, and used for thin film deposition, chemical synthesis, etching, surface treatments and sterilization. The surface properties of a general purpose polystyrene (GPPS) plate treated with RF atmospheric pressure plasma (APP) can be modified by subsequent washing. In this paper,

Yan Zhao; Shen Tang; Sung-Woon Myung; Na Lu; Ho-Suk Choi

2006-01-01

344

Electrical Features of Radio-frequency, Atmospheric-pressure, Bare-metallic-electrode Glow Discharges  

Microsoft Academic Search

Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas with bare metallic electrodes have promising prospects\\u000a in the fields of plasma-aided etching, deposition, disinfection and sterilization, etc. In this paper, an induced gas discharge\\u000a approach is proposed for obtaining the RF, atmospheric-pressure, ?-mode, glow discharges with pure nitrogen or air as the\\u000a primary plasma-working gas using bare metallic electrodes. The discharge characteristics,

He-Ping Li; Wen-Ting Sun; Hua-Bo Wang; Guo Li; Cheng-Yu Bao

2007-01-01

345

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

Microsoft Academic Search

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

Richard J. Rutkowski

1994-01-01

346

Electrical Analysis of Pulsed Positive Multipoint Corona Discharges in Air at Atmospheric Pressure  

Microsoft Academic Search

Positive corona discharges in dry air at atmospheric pressure operating with a pulsed voltage supply are electrically analyzed for a multitip configuration using an increasing number of tips, from one up to six. The peak value of the instantaneous discharge current as a function of the number of tips and the modification of the branching structure are discussed. Index Terms—Atmospheric

A. Abahazem; A. Mraihi; N. Merbahi; M. Yousfi; O. Eichwald

2011-01-01

347

Measurement of the First Townsend's Ionization Coefficients in Helium, Air, and Nitrogen at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

In the past the first Townsend’s ionization coefficient ? could only be measured with Townsend discharge in gases at low pressure. After realizing Townsend discharge in some gases at atmospheric pressure by using dielectric barrier electrodes, we had developed a new method for measuring ? coefficient at atmospheric pressure, a new optical method based on the discharge images taken with ICCD camera. With this newly developed method ? coefficient in helium, nitrogen and air at atmospheric pressure were measured. The results were found to be in good agreement with the data obtained at lower pressure but same reduced field E/p by other groups. It seems that the value of ? coefficient is sensitive to the purity of the working gas.

Ran, Junxia; Luo, Haiyun; Yue, Yang; Wang, Xinxin

2014-07-01

348

Diagnostics of plasma-biological surface interactions in low pressure and atmospheric pressure plasmas  

NASA Astrophysics Data System (ADS)

Mechanisms of plasma-surface interaction are required to understand in order to control the reactions precisely. Recent progress in atmospheric pressure plasma provides to apply as a tool of sterilization of contaminated foodstuffs. To use the plasma with safety and optimization, the real time in situ detection of free radicals - in particular dangling bonds by using the electron-spin-resonance (ESR) technique has been developed because the free radical plays important roles for dominantly biological reactions. First, the kinetic analysis of free radicals on biological specimens such as fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge. We have obtained information that the in situ real time ESR signal from the spores was observed and assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal was correlated with a link to the inactivation of the fungal spore. Second, we have studied to detect chemical modification of edible meat after the irradiation. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS) and ESR, signals give qualification results for chemical changes on edible liver meat. The in situ real-time measurements have proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

Ishikawa, Kenji; Hori, Masaru

2014-08-01

349

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

SciTech Connect

Atmospheric pressure glow discharges generated between parallel-plate electrodes in helium have been characterized using temporally resolved emission spectra. The variation of typical spectral lines over time has been analyzed. In helium with a low concentration of N{sub 2}, the emission of He at 706.5 nm is dominant and appears 500 ns earlier than N{sub 2}{sup +} first negative bands, indicating low reaction rates of Penning ionization and charge transfer in the initial stage. During the decay, it is the Penning ionization caused by He metastables with a long lifetime rather than the charge transfer reaction that leads to the long decay of N{sub 2}{sup +} emissions. When helium contains a higher concentration of N{sub 2} molecules, the N{sub 2}{sup +} first negative bands become the most intense, and emissions from He, N{sub 2}{sup +}, and O exhibit similar behavior as they increase. The emissions last for a shorter time under such conditions because of rapid consumption of He metastables and He{sub 2}{sup +}.

Liu Yaoge; Hao Yanpeng; Zheng Bin [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

2012-09-15

350

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

351

A new theoretical solution of the effect of atmospheric pressure on water level  

NASA Astrophysics Data System (ADS)

Based on the partial differential equation governing the effect of atmospheric pressure on water level of confined well, deriving the boundary condition and considering the seepage water between well and aquifer, the author obtained the analytical solution of water level change in time domain under the action of an atmospheric pressure history with the Laplace transform method. This solution is composed of two terms:stable and retarded terms. The stable term is the multiplication of barometric efficiency and simultaneous atmospheric pressure, and it implies the value of water level after infinite time when the atmospheric pressure is a constant from the time in question. The retarded term is the transient process due to the time lag of water exchange between well and aquifer. From the solution, it is obtained that the interference of atmospheric pressure on water level is the integral superimposition of the contribution of all atmospheric pressure changes before the time in question. So that, we further found out the response function of pulsive atmospheric pressure history. Calculation shows: (1) The pulsive response function starts from zero and tends to a steady value, which is proportional to the barometric efficiency, when the time tends to infinity; (2) The retarded time depends on the mechanical property of aquifer and the radius of well. The larger the seepage coefficient, the smaller the radius of well and the thicker the aquifer, then the shorter the retarded time gets. This solution can be used as the theoretical basis for further analysis of the atmospheric effect and practical correcting method in the future.

Zhao, Peng-Jun

1995-05-01

352

Cold Event in the South Atlantic Bight During Summer of 2003: Anomalous Hydrographic and Atmospheric Conditions.  

E-print Network

1 Cold Event in the South Atlantic Bight During Summer of 2003: Anomalous Hydrographic , Francisco E. Werner1 , John M. Bane 1 and Robert Weisberg3 Short title: SAB SUMMER UPWELLING DRAFT: June 15, GA 3 University of South Florida, St. Petersburg, FL #12;2 Abstract. Unusually cold sea

North Carolina at Chapel Hill, University of

353

Comparison of electrical energy efficiency of atmospheric and high-pressure electrolysers  

Microsoft Academic Search

Efforts are being made to produce highly pressurised electrolysers to increase the overall energy efficiency by eliminating mechanical compression. However, in-depth modelling of electrolysers suggests that electrolysis at atmospheric pressure is electrically more energy efficient if parasitic energy consumption and gas losses are incorporated in both cases. The reversible cell voltage increases with increasing pressures. The electrode activation and Ohmic

Amitava Roy; Simon Watson; David Infield

2006-01-01

354

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

355

Study of the atmospheric pressure loading signal in very long baseline interferometry observations  

Microsoft Academic Search

Redistribution of air masses due to atmospheric circulation causes loading deformation of the Earth's crust, which can be as large as 20 mm for the vertical component and 3 mm for horizontal components. Rigorous computation of site displacements caused by pressure loading requires knowledge of the surface pressure field over the entire Earth surface. A procedure for computing three-dimensional displacements

Leonid Petrov; Jean-Paul Boy

2004-01-01

356

Experimental characterization of an argon laminar plasma jet at atmospheric pressure  

Microsoft Academic Search

This paper deals with a dc laminar pure argon plasma jet operating at atmospheric pressure in ambient air that was experimentally studied in order to obtain temperature and velocity. Plasma jet temperature was evaluated by optical emission spectroscopy and the plasma jet velocity was determined by various methods using a pressure sensor. It is shown that the maximum plasma jet

Emilie Langlois-Bertrand; Charles de Izarra

2011-01-01

357

Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system  

Microsoft Academic Search

Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and

K. Aktas; S. Acar; B. G. Salamov

2011-01-01

358

Instrumentation for measuring static pressure fluctuations within the atmospheric boundary layer  

Microsoft Academic Search

An instrument is described which is capable of making Eulerian measurements of microscale fluctuations in the static pressure when it is placed within the turbulent flow of the lower atmospheric boundary layer. The sampling ports are located on an accurately shaped streamlined circular disc; dynamic pressure changes at these ports, due to the flow fluctuations, are small when compared to

J. A. Elliott

1972-01-01

359

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

360

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

361

Verification by Viking landers of earlier radio occultation measurements of surface atmospheric pressure on Mars  

NASA Technical Reports Server (NTRS)

The landing of Viking 1 in Chryse Planitia on July 20, 1976 provided the first opportunity to obtain measurements of atmospheric pressure directly from the surface of Mars. A computation was conducted to predict the atmospheric pressure at the landing site before the landing itself. The relative altitude between occultation points and the Viking 1 site was obtained with the aid of earth-based planetary radar data taken in 1967. The data cover Martian latitudes from 19 deg N to 24 deg N. The investigation indicates that the radio occultation results from Mariner 9 closely correspond to the actual surface pressure on Mars.

Kliore, A. J.

1977-01-01

362

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

SciTech Connect

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

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

2008-12-29

363

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

NASA Technical Reports Server (NTRS)

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

Spanarkel, Robert; Drew, Malcolm C.

2002-01-01

364

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

365

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

366

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

367

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

368

Generation of large-volume, atmospheric-pressure, nonequilibrium plasmas  

Microsoft Academic Search

A review is presented of the issues associated with the generation of large-volume, high-pressure, nonequilibrium plasmas, as well as the approaches that have been developed for generating these plasmas using electrical discharges in gases. The various instabilities that have been overcome to obtained these plasmas as well as the techniques for quenching them are also reviewed. Last, recent efforts to

E. E. Kunhardt

2000-01-01

369

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

370

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

2013-01-01

371

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

E-print Network

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 [1] 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 10**15 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 L...

Jeanmonod, N; Casas-Cubillos, J

2006-01-01

372

Electron field emission from carbon nanotubes in air for excitation of atmospheric pressure microplasma.  

PubMed

Electron field emission (FE) from carbon nanotubes (CNTs) in air for excitation of atmospheric pressure microplasma was investigated in a scanning electron microscope (SEM). The results showed that, the FE properties of CNTs at 10 kPa and lower pressures were the same as those in vacuum. At pressures more than 10 kPa, the FE threshold voltages in air were higher than those in vacuum and increased with increasing air pressure. When the FE threshold voltage became higher than the gas breakdown voltage, microplasma was ignited before FE appearance. FE properties of CNTs were stable in air before appearing gas discharges. PMID:19441423

Zou, Q; Hatta, A

2009-02-01

373

A comparison between E-beam irradiation and high pressure treatment for cold-smoked salmon sanitation: microbiological aspects  

Microsoft Academic Search

The effectiveness of electron beam irradiation and high pressure treatment for the sanitation of cold-smoked salmon from two points of view, microbial safety and shelf-life extension, was compared. From the response of L. monocytogenes INIA H66a to irradiation, a D value of 0.51kGy was calculated. For samples stored at 5°C, 1.5kGy would be sufficient to attain a Food Safety Objective

M. Medina; M. C. Cabeza; D. Bravo; I. Cambero; R. Montiel; J. A. Ordóñez; M. Nuñez; L. Hoz

2009-01-01

374

Atmospheric pressure-forced subinertial variations in the transport through the Korea Strait  

NASA Astrophysics Data System (ADS)

Transport variations with periods of 3 ~ 5 days have been measured in the Korea (Tsushima) Strait by cross-strait cable voltage fluctuations and by direct, long-term measurement. Here we show that these variations can be explained in part by large-scale atmospheric pressure fluctuations over the East (Japan) Sea. First, using basin-wide averages of atmospheric pressure and sea surface height we show that sea surface height in the East Sea is not in isostatic equilibrium with atmospheric pressure, and that the imbalance is correlated with transport fluctuations. Second, we use a simple model to estimate the relationship between these quantities. The model displays a Helmholtz-like resonance in the observed range of periods and is in reasonable agreement with the observed transport variations.

Lyu, Sang Jin; Kim, Kuh; Perkins, Henry T.

2002-05-01

375

On the growth mode of two-lobed curvilinear graphene domains at atmospheric pressure  

PubMed Central

We demonstrate the chemical vapor deposition (CVD) growth of 2-lobed symmetrical curvilinear graphene domains specifically on Cu{100} surface orientations at atmospheric pressure. We utilize electron backscattered diffraction, scanning electron microscopy and Raman spectroscopy to determine an as-yet unexplored growth mode producing such a shape and demonstrate how its growth and morphology are dependent on the underlying Cu crystal structure especially in the high CH4:H2 regime. We show that both monolayer and bilayer curvilinear domains are grown on Cu{100} surfaces; furthermore, we show that characteristic atmospheric pressure CVD hexagonal domains are grown on all other Cu facets with an isotropic growth rate which is more rapid than that on Cu{100}. These findings indicate that the Cu-graphene complex is predominant mechanistically at atmospheric pressure, which is an important step towards tailoring graphene properties via substrate engineering. PMID:23999168

Kumar, Kitu; Yang, Eui-Hyeok

2013-01-01

376

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

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

377

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

Riris, H.; Rodriguez, M.; Stephen, M.; Hasselbrack, W.; Allan, G.; Mao, J.; Kawa, S. R.; Weaver, C. J.

2010-12-01

378

Alkali vapor pressure modulation on the 100 ms scale in a single-cell vacuum system for cold atom experiments  

NASA Astrophysics Data System (ADS)

We describe and characterize a device for alkali vapor pressure modulation on the 100 ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors.

Dugrain, Vincent; Rosenbusch, Peter; Reichel, Jakob

2014-08-01

379

Alkali vapor pressure modulation on the 100 ms scale in a single-cell vacuum system for cold atom experiments.  

PubMed

We describe and characterize a device for alkali vapor pressure modulation on the 100 ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors. PMID:25173251

Dugrain, Vincent; Rosenbusch, Peter; Reichel, Jakob

2014-08-01

380

Characteristics of radio-frequency atmospheric pressure dielectric-barrier discharge with dielectric electrodes  

SciTech Connect

An experimental investigation to characterize the properties and highlight the benefits of atmospheric pressure radio-frequency dielectric-barrier discharge (rf DBD) with dielectric electrodes fabricated by anodizing aluminium substrate is presented. The current-voltage characteristics and millisecond images are used to distinguish the ? and ? modes. This atmospheric rf DBD is observed to retain the discharge volume without constriction in ? mode. Optical emission spectroscopy demonstrates that the large discharge current leads to more abundant reactive species in this plasma source.

Hussain, S., E-mail: shussain@uos.edu.pk, E-mail: shussainuos@yahoo.com; Qazi, H. I. A.; Badar, M. A. [Department of Physics, University of Sargodha, 40100 Sargodha (Pakistan)] [Department of Physics, University of Sargodha, 40100 Sargodha (Pakistan)

2014-03-15

381

Characteristics of radio-frequency atmospheric pressure dielectric-barrier discharge with dielectric electrodes  

NASA Astrophysics Data System (ADS)

An experimental investigation to characterize the properties and highlight the benefits of atmospheric pressure radio-frequency dielectric-barrier discharge (rf DBD) with dielectric electrodes fabricated by anodizing aluminium substrate is presented. The current-voltage characteristics and millisecond images are used to distinguish the ? and ? modes. This atmospheric rf DBD is observed to retain the discharge volume without constriction in ? mode. Optical emission spectroscopy demonstrates that the large discharge current leads to more abundant reactive species in this plasma source.

Hussain, S.; Qazi, H. I. A.; Badar, M. A.

2014-03-01

382

Surface Passivation of Crystalline Silicon Solar Cells by Atmospheric Pressure Chemical Vapor Deposition  

Microsoft Academic Search

SiO2 films prepared by atmospheric pressure chemical vapor deposition (APCVD) were investigated for surface passivation of crystalline Si solar cells. The passivation effects of APCVD SiO2 for p-type Si substrates were evaluated by measuring excess minority carrier lifetimes. Effective surface recombination velocities S eff were decreased by successive annealing in N2 atmosphere at 300-700 degC without the degradation of the

Ryusuke Imai; Tsukasa Ishiwata; Hitoshi Sai; Naoya Yamamoto; Koji Arafune; Yoshio Ohshita; Masafumi Yamaguchi

2006-01-01

383

A constant altitude flight survey method for mapping atmospheric ambient pressures and systematic radar errors  

NASA Technical Reports Server (NTRS)

The flight test technique described uses controlled survey runs to determine horizontal atmospheric pressure variations and systematic altitude errors that result from space positioning measurements. The survey data can be used not only for improved air data calibrations, but also for studies of atmospheric structure and space positioning accuracy performance. The examples presented cover a wide range of radar tracking conditions for both subsonic and supersonic flight to an altitude of 42,000 ft.

Larson, T. J.; Ehernberger, L. J.

1985-01-01

384

Microwave air plasma source at atmospheric pressure: Experiment and theory  

SciTech Connect

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({gamma}) 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 {approx}2 eV) have been detected.

Tatarova, E.; Dias, F. M.; Felizardo, E.; Pinheiro, M. J.; Ferreira, C. M. [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Gordiets, B. [Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Moscow (Russian Federation); Henriques, J.

2010-12-15

385

Frequency of collisions between ion and neutral particles from the cloning characteristics of filamentary currents in an atmospheric pressure helium plasma jet  

NASA Astrophysics Data System (ADS)

In this paper, a cold He atmospheric pressure plasma jet that is generated using a dielectric barrier discharge configuration device is presented. This device is equipped with double-grounded ring electrodes that are driven by a sinusoidal excitation voltage. The properties of the cloning of filamentous current are studied. The frequency of the collisions between the ion and the neutral particles is calculated by measuring the current phase difference between the filamentous current and its corresponding clone. The frequency of the collisions between the ion and the neutral particles is of the order of 108 Hz.

Qi, Bing; Zhang, Mengdie; Pan, Lizhu; Zhou, Qiujiao; Huang, Jianjun; Liu, Ying

2015-02-01

386

Spectroscopic diagnosis of an atmospheric-pressure waveguide-based microwave N2–Ar plasma torch  

NASA Astrophysics Data System (ADS)

An atmospheric-pressure N2–Ar plasma is investigated by means of optical emission spectroscopic diagnosis concerning the variation of its fundamental parameters, electron density and plasma temperature, and concentrations of ionized molecular nitrogen, atomic nitrogen, and excited argon with the tuning variables, such as the input power and the ratio of N2 in N2–Ar mixture gas, in the discharge region of the plasma torch. Moreover, qualitative discussions are delivered with respect to the mechanisms for nitrogen dissociation and influence of the Ar component on the N2 plasma discharge at atmospheric pressure.

Li, Shou-Zhe; Chen, Chuan-Jie; Zhang, Xin; Zhang, Jialiang; Wang, Yong-Xing

2015-04-01

387

Columnar discharge mode between parallel dielectric barrier electrodes in atmospheric pressure helium  

SciTech Connect

Using a fast-gated intensified charge-coupled device, end- and side-view photographs were taken of columnar discharge between parallel dielectric barrier electrodes in atmospheric pressure helium. Based on three-dimensional images generated from end-view photographs, the number of discharge columns increased, whereas the diameter of each column decreased as the applied voltage was increased. Side-view photographs indicate that columnar discharges exhibited a mode transition ranging from Townsend to glow discharges generated by the same discharge physics as atmospheric pressure glow discharge.

Hao, Yanpeng; Zheng, Bin; Liu, Yaoge [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)] [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

2014-01-15

388

Experimental study on the emission spectra of microwave plasma at atmospheric pressure  

SciTech Connect

An experimental study on microwave plasma at atmospheric pressure was conducted by employing optical emission spectroscopy. Based on a microwave plasma generation device developed for nanoparticle synthesis, we studied the influence of input microwave power and gas flow rate on the optical emission behaviors and electron temperature of plasma using Ar, He, and N{sub 2} as working gas, respectively. The physics behind these behaviors was discussed. The results are useful in characterizing microwave plasma at atmospheric pressure and can be used for improving nanoparticle synthesis system for commercial use in the future.

Zhang, Boya; Wang, Qiang; Zhang, Guixin, E-mail: guixin@mail.tsinghua.edu.cn [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Liao, Shanshan [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Shenzhen Power Supply Co. Ltd., Shenzhen 518000, Guangdong (China)

2014-01-28

389

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

390

Microwave-excited atmospheric pressure plasma jet with wide aperture for the synthesis of carbon nanomaterials  

NASA Astrophysics Data System (ADS)

Atmospheric pressure chemical vapor deposition (APCVD) has preferable properties to the mass production of carbon nanomaterials. Here, we describe a specially-designed microwave-excited atmospheric pressure plasma jet (MW-APPJ) with a 10-mm-wide nozzle based on microstrip line. The MW-APPJ is applied to an APCVD process and nanocrystalline diamond films are successfully deposited on silicon substrates using a mixture gas of Ar/CH4/H2 even in ambient air. The MW-APPJ technology could be suitable for the large-area APCVD system for the synthesis of carbon nanomaterials due to its arrayed configuration for the enlargement of plasma area.

Kim, Jaeho; Sakakita, Hajime; Ohsaki, Hiroyuki; Katsurai, Makoto

2015-01-01

391

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

SciTech Connect

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

Jiang, Tianyu NMI [ORNL] [ORNL; Evans, Katherine J [ORNL] [ORNL; Deng, Yi [Georgia Institute of Technology, Atlanta] [Georgia Institute of Technology, Atlanta; Dong, Xiquan [University of North Dakota, Grand Forks] [University of North Dakota, Grand Forks

2014-01-01

392

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

393

Surface atmospheric pressure excitation of the translational mode of the inner core  

NASA Astrophysics Data System (ADS)

Using hourly atmospheric surface pressure field from ECMWF (European Centre for Medium-Range Weather Forecasts) and from NCEP (National Centers for Environmental Prediction) Climate Forecast System Reanalysis (CFSR) models, we show that atmospheric pressure fluctuations excite the translational oscillation of the inner core, the so-called Slichter mode, to the sub-nanogal level at the Earth surface. The computation is performed using a normal-mode formalism for a spherical, self-gravitating anelastic PREM-like Earth model. We determine the statistical response in the form of power spectral densities of the degree-one spherical harmonic components of the observed pressure field. Both hypotheses of inverted and non-inverted barometer for the ocean response to pressure forcing are considered. Based on previously computed noise levels, we show that the surface excitation amplitude is below the limit of detection of the superconducting gravimeters, making the Slichter mode detection a challenging instrumental task for the near future.

Rosat, S.; Boy, J.-P.; Rogister, Y.

2014-02-01

394

Postharvest Biology and Technology 26 (2002) 181189 Carbon dioxide-enriched atmospheres during cold storage  

E-print Network

cold storage limit losses from Botrytis but accelerate rachis browning of `Redglobe' table grapes storage. During the 1998 season, early (14% soluble solids concentration, SSC) and late harvested (17% SSC' grapes were kept in 12 kPa CO2 +6 kPa O2 in comparison with standard commercial storage practices of SO2

Crisosto, Carlos H.

395

Atmospheric-Pressure PECVD Coating and Plasma Chemical Etching for Continuous Processing  

Microsoft Academic Search

Plasma processing at atmospheric pressure (APPlasmas) has attractions for both economic and technological reasons. Potential costs-saving factors are associated with online-processing capability and increase throughput due to high deposition rates. Capital cost savings for both equipment and line space (foot print), and relative ease of integration, are further benefits in comparison to low-pressure-technology approaches. Three types of APPlasmas are considered

Volkmar Hopfe; David W. Sheel

2007-01-01

396

High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays  

Microsoft Academic Search

Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite

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

2005-01-01

397

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

398

Effects of long-period solar activity fluctuation on temperature and pressure of the terrestrial atmosphere  

NASA Technical Reports Server (NTRS)

The present state of research on the influence of solar sunspot activity on tropospheric temperature and pressure is reviewed. The existence of an 11-year temperature cycle of 5 different types is affirmed. A cyclic change in atmospheric pressure, deducing characteristic changes between 11-year cycles is discussed. The existence of 80-year and 5-to-6-year cycles of temperature is established, and physical causes for birth are suggested.

Rubashev, B. M.

1978-01-01

399

Ozone generation using atmospheric pressure glow discharge in air  

NASA Astrophysics Data System (ADS)

This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltage, gas flow rate and reaction chamber dimensions resulted in a highest efficiency of production of almost 350 g kWh-1 and confirms its potential as an important ozone generation technology.

Buntat, Z.; Smith, I. R.; Razali, N. A. M.

2009-12-01

400

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

401

Use of Zircaloy 4 material for the pressure vessels of hot and cold neutron sources and beam tubes for research reactors  

Microsoft Academic Search

The material Zircaloy 4 can be used for the pressure retaining walls for the cold and hot neutron sources and beam tubes. For the research reactor FRM-II of the Technical University Munich, Germany, the material Zircaloy 4 were chosen for the vessels of the cold and hot neutron source and for the beam tube No. 6.The sheets and forgings of

Erwin Gutsmiedl; Anton Scheuer

2002-01-01

402

The oceanic response of the Turkish Straits System to an extreme drop in atmospheric pressure  

NASA Astrophysics Data System (ADS)

across all four entry/exit sections of the Dardanelles Strait and the Bosphorus Strait simultaneously measured the response of the Turkish Straits System to the passage of a severe cyclonic storm that included an atmospheric pressure drop of more than 30 mbar in less than 48 h. The bottom pressure response at the Aegean Sea side of the Dardanelles Strait was consistent with an inverted barometer response, but the response at the other sections did not follow an inverted barometer, leading to a large bottom pressure gradient through the Turkish Straits System. Upper-layer flow toward the Aegean Sea was reversed by the storm and flow toward the Black Sea was greatly enhanced. Bottom pressure across the Sea of Marmara peaked 6 h after the passage of the storm's minimum pressure. The response on the Dardanelles side was a combination of sea elevation and pycnocline depth rise, and the response on the Bosphorus side was an even greater sea elevation rise and a drop in pycnocline depth. The peak in bottom pressure in the Sea of Marmara was followed by another reverse in the flow through the Dardanelles Strait as flow was then directed away from the Sea of Marmara in both straits. A simple conceptual model without wind is able to explain fluctuations in bottom pressure in the Sea of Marmara to a 0.89-0.96 level of correlation. This stresses the importance of atmospheric pressure dynamics in driving the mass flux of the Turkish Strait System for extreme storms.

Book, Jeffrey W.; Jarosz, Ewa; Chiggiato, Jacopo; Be?iktepe, Å.?ükrü

2014-06-01

403

EDITORIAL: Atmospheric pressure non-thermal plasmas for processing and other applications  

NASA Astrophysics Data System (ADS)

Interest has grown over the past few years in applying atmospheric pressure plasmas to plasma processing for the benefits this can offer to existing and potential new processes, because they do not require expensive vacuum systems and batch processing. There have been considerable efforts to efficiently generate large volumes of homogeneous atmospheric pressure non-thermal plasmas to develop environmentally friendly alternatives for surface treatment, thin film coating, sterilization, decontamination, etc. Many interesting questions have arisen that are related to both fundamental and applied research in this field. Many concern the generation of a large volume discharge which remains stable and uniform at atmospheric pressure. At this pressure, depending on the experimental conditions, either streamer or Townsend breakdown may occur. They respectively lead to micro-discharges or to one large radius discharge, Townsend or glow. However, the complexity arises from the formation of large radius streamers due to avalanche coupling and from the constriction of the glow discharge due to too low a current. Another difficulty is to visually distinguish many micro-discharges from one large radius discharge. Other questions relate to key chemical reactions in the plasma and at the surface. Experimental characterization and modelling also need to be developed to answer these questions. This cluster collects up-to-date research results related to the understanding of different discharges working at atmospheric pressure and the application to polymer surface activation and thin film coating. It presents different solutions for generating and sustaining diffuse discharges at atmospheric pressure. DC, low-frequency and radio-frequency excitations are considered in noble gases, nitrogen or air. Two specific methods developed to understand the transition from Townsend to streamer breakdown are also presented. They are based on the cross-correlation spectroscopy and an electrical model.

Massines, Françoise

2005-02-01

404

Experimental and computational investigation of cold-flow through the turbine of the space-shuttle main engine high-pressure fuel turbopump .  

E-print Network

??Computational predictions and experimental measurements were made on the Naval Postgraduate School's cold-flow turbine test rig. The test turbine was the Space-Shuttle Main Engine, High-Pressure… (more)

McKee, Joseph R.

1998-01-01

405

Large-Scale Characteristics of the Atmospheric Boundary Layer in the Eastern Pacific Cold Tongue ITCZ Region  

Microsoft Academic Search

Observations from the Eastern Pacific Investigation of Climate 2001 (EPIC2001) field campaign and a simple mixed-layer model are used to study the large-scale structure and dynamics of the atmospheric boundary layer (ABL) in the eastern Pacific. Vertical and latitudinal distributions of the meridional pressure gradient, winds, and other variables are examined and the momentum balance of the mixed layer is

Michael McGauley; Chidong Zhang; Nicholas A. Bond

2004-01-01

406

Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce  

NASA Astrophysics Data System (ADS)

The objectives of this research were to determine photosynthesis, evapotranspiration and growth of lettuce at long-term low atmospheric pressure. Lettuce ( Lactuca sativa L . cv. Youmaicai) plants were grown at 40 kPa total pressure (8.4 kPa p) or 101 kPa total pressure (20.9 kPa p) from seed to harvest for 35 days. Germination rate of lettuce seeds decreased by 7.6% at low pressure, although this was not significant. There was no significant difference in crop photosynthetic rate between hypobaria and ambient pressure during the 35-day study. The crop evapotranspiration rate was significantly lower at low pressure than that at ambient pressure from 20 to 30 days after planting (DAP), but it had no significant difference before 20 DAP or after 30 DAP. The growth cycle of lettuce plants at low pressure was delayed. At low pressure, lettuce leaves were curly at the seedling stage and this disappeared gradually as the plants grew. Ambient lettuce plants were yellow and had an epinastic growth at harvest. The shoot height, leaf number, leaf length and shoot/root ratio were lower at low pressure than those at ambient pressure, while leaf area and root growth increased. Total biomass of lettuce plants grown at two pressures had no significant difference. Ethylene production at low pressure decreased significantly by 38.8% compared with ambient pressure. There was no significant difference in microelements, nutritional phytochemicals and nitrate concentrations at the two treatments. This research shows that lettuce can be grown at long-term low pressure (40 kPa) without significant adverse effects on seed germination, gas exchange and plant growth. Furthermore, ethylene release was reduced in hypobaria.

Tang, Yongkang; Guo, Shuangsheng; Dong, Wenping; Qin, Lifeng; Ai, Weidang; Lin, Shan

2010-09-01

407

Radial Measurements of Gas Discharge Parameters of Atmospheric Pressure Microplasma  

NASA Astrophysics Data System (ADS)

In this work Abel inversion technique was used for radial measurements of the microplasma in Ar-2%H2 flow at open atmosphere. The gas discharge parameters were investigated using spatially resolved high resolution optical emission spectroscopy (OES) to allow acquisition of OH (A 2?+, ? = 0 ?X 2?, ?? = 0) rotational bands at 306.357 nm, Ar I 603.213 nm line and N2(C3?u, ? = 0 ?B3?g, ?? = 0) second positive system with the band head at 337.13 nm. The nonthermal plasma was generated between microhollow anode ( 500 ?m inner diameter) and a cathode copper foil, fed by direct current source for a current ranging from 20 mA to 100 mA (Townsend discharge from 20 mA to 30 mA, normal glow discharge from 30 mA to 80 mA at 210 V and abnormal discharge beyond 90 mA). The 1.5 mm length cylindrical-shape plasma has an outspread bright disk (negative glow region) near the cathode surface. Besides the gas temperature, the excitation temperature was measured radially for a current ranging from 20 mA to 100 mA, either from Boltzmann-plot of Ar I 4p - 4s and 5p - 4s transitions of excited argon or from Cu I two lines method of excited cuprum atoms released from the cathode surface. The measurements showed a nearly bell-shaped distribution of these temperatures, peaked at 120 ?m from the center with the minimum at the plasma border. The average excitation temperature was about 8000 K (maximum 10,000 K) and the average rotational temperature was about 650 K (maximum 800 K) from 20 K to 100 K. For the N2 second positive system with ?? = -2 it was estimated the vibrational temperature for the bright disk (1500 K to 5000 K). H? line Stark broadening was employed to define the electron number density of the negative glow (1015cm-3).

Caetano, R.; Hoyer, Y. D.; Barbosa, I. M.; Grigorov, K. G.; Sismanoglu, B. N.

2013-07-01

408

Atmospheric pressure intercalation of oxygen via wrinkles between graphene and a metal  

E-print Network

contrast AFM images (SI, Figure S2) allows one to identify graphene-free and graphene-covered regions.15Atmospheric pressure intercalation of oxygen via wrinkles between graphene and a metal Amina with graphene, an atomically thin sheet of carbon atoms in a honeycomb lattice. These prospects are urging

Paris-Sud XI, Université de

409

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

Microsoft Academic Search

Plasma polymers of acrylic acid were obtained using an atmospheric pressure discharge system. The plasma polymerization reactor uses a dielectric barrier discharge, with the polyethylene terephthalate dielectric acting as substrate for deposition. The plasma was characterized by specific electrical measurements, monitoring the applied voltage and the discharge current. Based on the spatially resolved optical emission spectroscopy, we analyzed the distribution

Ionut Topala; Nicoleta Dumitrascu; Gheorghe Popa

2009-01-01

410

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

411

Atmospheric Pressure Glow Discharge Plasma and Surface Modification of PET Textile by APGDP  

Microsoft Academic Search

Comparing with traditional chemistry method, surface modification of Polyethylene terephthalate (PET) fabrics by using of Atmospheric Pressure Glow Discharge Plasma (APGDP) has many advantages, such as low cost, low pollution and low energy consumption. So it has huge application in textile industry due to no requirement for vacuum system. In this paper, the generation and the characteristics of APGDP on

Biao Gu; Ru Chen; Yin Xu; Xiang Deng; Qingjun Shi

2002-01-01

412

Quasi-static vapor pressure measurements on reactive systems in inert atmosphere box  

NASA Technical Reports Server (NTRS)

Apparatus makes vapor pressure measurements on air-sensitive systems in an inert atmosphere glove box. Once the apparatus is loaded with the sample and all connections made, all measuring operations may be performed outside the box. The apparatus is a single-tube adaptation of the double-tube quasi-static technique.

Fischer, A. K.

1968-01-01

413

Atmospheric pressure glow discharge deposition of thermo-sensitive poly (N-isopropylacrylamide)  

NASA Astrophysics Data System (ADS)

In this paper, a self-made atmospheric pressure dielectric barrier discharge reactor on intermediate frequency is brought forward and developed, which is equipped with power supply of 1-20 KHz, and the working gas is argon. The experimental results show that is a very stable and uniform atmospheric pressure glow discharge (APGD). Through a series of experiments, the waveforms of single pulse and multi-pulse glow discharge were both obtained. The voltage amplitude, discharge gap and dielectric material are studied, and the conditions of multi-pulse glow discharge are discussed as well. The novel methods of depositing poly (N-isopropylacrylamide) (PNIPAAm) coatings on the surface of glass slides and PS petri dish are provided by atmospheric pressure plasma polymerization. PNIPAAm can be obtained by plasma polymerization of N-isopropylacrylamide using the self-made equipment of atmospheric pressure plasma vapor treatment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. SEM analysis has revealed that the PNIPAAm coatings were formed on the surface of the smooth glass slides. Further evaluation by using XPS, it has shown the presence of PNIPAAm. The wettability can be significantly modified by changing of the temperatures at above and below of the lower critical solution temperature (LCST) from the data of the contact angle test. These results have advantage for further application on the thermo-sensitive textile materials.

Shao, M.; Tang, X. L.; Wen, D.; Chen, Y.; Qiu, G.

2013-12-01

414

DNA strand scission induced by a non-thermal atmospheric pressure plasma jet.  

PubMed

The DNA molecule is observed to be very susceptible to short-term exposures to an atmospheric pressure plasma jet. The DNA damage induced by plasma-generated species, i.e. excited atoms, charged particles, electrons and UV light is determined. PMID:20556293

Ptasi?ska, Sylwia; Bahnev, Blagovest; Stypczy?ska, Agnieszka; Bowden, Mark; Mason, Nigel J; Braithwaite, Nicholas St J

2010-07-28

415

Carbon foam produced from fluid catalytic cracking slurry at atmospheric pressure  

Microsoft Academic Search

Pitch-based carbon foam containing pores of diameter 150–400 ?m was produced from an intermediate pitch obtained from aromatic rich oil extracted from heavy oil FCC (fluid catalytic cracking) slurry by heating at atmospheric pressure. The effect of molecular weight distribution of the pitch on the formation of the foam was studied qualitatively. The variation of microscopic morphology, crystallite size, the

Xiao-jun YANG; Qing-fang ZHA; Hong-nan LI; Xue-jun LI; Xiang-ling CHENG

2008-01-01

416

Atmospheric pressure discharge plasma decomposition for gaseous air contaminants-trichlorotrifluoroethane and trichloroethylene  

Microsoft Academic Search

The decomposition performance of gaseous environmental destructive contaminants in air by using atmospheric pressure discharge plasma including the surface discharge induced plasma chemical processing (SPCP) was examined. The main contaminants tested were chlorofluorocarbon (CFC-113) and trichloroethylene, typically. The discharge exciting frequency range studied was wide-50 Hz to 50 kHz. Results showed the low frequency discharge requires high voltage to inject

Tetsuji Oda; Ryuichi Yamashita; Tadashi Takahashi; Senichi Masuda

1996-01-01

417

Atmospheric pressure chemical ionisation mass spectrometry for in vivo analysis of volatile flavour release  

Microsoft Academic Search

To follow volatile flavour release in the expired air of people during eating, several physiological and analytical constraints must be observed to obtain good quality data. An interface has been developed to sample air from the nose and ionise the volatile compounds contained therein by atmospheric pressure chemical ionisation. The ions formed are detected in a quadrupole mass spectrometer. The

A. J. Taylor; R. S. T. Linforth; B. A. Harvey; A. Blake

2000-01-01

418

Images of biological samples undergoing sterilization by a glow discharge at atmospheric pressure  

Microsoft Academic Search

Among the various industrial uses of the glow discharge at atmospheric pressure (GDAP), biological applications such as sterilization are under investigation. In this paper, we present images of a liquid medium (Luria-Bertani broth with tetracycline) contaminated by Escherichia coli bacteria (strain PER 322) undergoing plasma treatment. In most cases, it is found that an exposure time of two to 20

Mounir Laroussi; Gary S. Sayler; Battle B. Glascock; Bruce McCurdy; Mary E. Pearce; Nathan G. Bright; Chad M. Malott

1999-01-01

419

High-speed photographs of a dielectric barrier atmospheric pressure plasma jet  

Microsoft Academic Search

The propagation of an atmospheric pressure plasma jet (APPJ) is investigated by use of an intensified charge coupled device (ICCD) camera. It is shown that the APPJ is mainly an electrical phenomenon and not a flow related one. The jet does not consist of a voluminous plasma. Much more, the presented plasma source acts like a \\

M. Teschke; J. Kedzierski; E. G. Finantu-Dinu; D. Korzec; J. Engemann

2005-01-01

420

Continental Shelf Waves and the Effects of Atmospheric Pressure and Wind Stress on Sea Level  

Microsoft Academic Search

The 'barometer factor,' or ratio of daily mean sea level change to atmospheric pressure change, is reported for 17 Australian tide stations. The barometer factor is shown to be appreciably less than the theoretical value at four stations on the east Australian coast and appreciably greater than the theoretical value at two stations on the west Australian coast. Barometer factors

B. V. Hamon

1966-01-01

421

Nonthermal decontamination of biological media by atmospheric-pressure plasmas: review, analysis, and prospects  

Microsoft Academic Search

Although the use of an electrical discharge to disinfect water was suggested and applied more than a hundred years ago, basic and applied research on the interaction of plasmas with biological media was extensively carried out only relatively recently. In this context, a review of various works on the germicidal effects of atmospheric pressure, \\

Mounir Laroussi

2002-01-01

422

Atmospheric pressure loading corrections applied to GPS data at the observation level  

Microsoft Academic Search

Space-geodetic techniques can detect elastic deformation of the Earth caused by atmospheric pressure loading (ATML). However, it has not yet been demonstrated whether these surface displacements should be accounted for at the time of reduction of the observations or by applying time-averaged values to the coordinates after the analysis of the observations. An analysis of the power spectral density of

P. Tregoning; T. van Dam

2005-01-01

423

Plasma jet treatment of five polymers at atmospheric pressure: surface modifications and the relevance for adhesion  

Microsoft Academic Search

The polymers PET, PA6, PVDF, HD-PE, and PP are activated by a commercially available plasma jet system at atmospheric pressure to improve adhesive bondability. The adhesion properties of the activated surfaces are evaluated by lap shear tests. The results are correlated with the surface properties that are investigated by XPS, AFM, and contact angle measurements. In addition the influence of

Michael Noeske; Jost Degenhardt; Silke Strudthoff; Uwe Lommatzsch

2004-01-01

424

Atmospheric pressure plasma jet: Effect of electrode configuration, discharge behavior, and its formation mechanism  

Microsoft Academic Search

Atmospheric pressure plasma jet (APPJ) can protrude several centers into the ambient air; therefore it holds remarkable promise for many innovative applications. The mechanism underlying this nonthermal discharge, however, remains unsettled that it has been often taken as resulting from dielectric barrier discharge or vaguely referred as streamerlike. We generated APPJ by using a quartz capillary tube with three distinct

Nan Jiang; Ailing Ji; Zexian Cao

2009-01-01

425

Electrode Erosion in Pulsed Arc for Generating Air Meso-Plasma Jet under Atmospheric Pressure  

Microsoft Academic Search

Various materials of the rod electrode were examined in pulsed arc of PEN-Jet (Plasma ENergized-Jet) with working gas of air, which can be used for the surface treatment under atmospheric pressure. The erosion of the rod electrode was measured and it surface was observed. The amount of erosion and surface appearance were found to be different for the materials, input

Hajime Shiki; Junpei Motoki; Hirofumi Takikawa; Tateki Sakakibara; Yoshimi Nishimura; Shigeji Hishida; Takashi Okawa; Takeshi Ootsuka

2007-01-01

426

Atmospheric pressure air-plasma jet evolved from microdischarges: Eradication of E. coli with the jet  

Microsoft Academic Search

An atmospheric-pressure air-plasma jet operating at 60 Hz ac is presented. A plasma jet with a length of 23 mm was produced by feeding air through a porous alumina dielectric installed between an outer electrode and a hollow inner electrode. Microdischarges in the porous alumina are ejected as a plasma jet from the outer electrode through a 1 mm hole,

Yong Cheol Hong; Won Seok Kang; Yoo Beom Hong; Won Ju Yi; Han Sup Uhm

2009-01-01

427

Production of ultrafine atmospheric pressure plasma jet with nano-capillary  

Microsoft Academic Search

The atmospheric pressure plasma jet (APPJ) has been developed to apply to the ultrafine process for future material processing. In this study, we tried to reduce the diameter of APPJs by using micro- or nano-capillary tubes. To measure the existence of the bullet-like charged particles from the capillary tip, the plasma flow generated from capillary tubes with a diameter of

Ryota Kakei; Akihisa Ogino; Futoshi Iwata; Masaaki Nagatsu

2010-01-01

428

FAST TRACK COMMUNICATION: Characteristics of atmospheric pressure plasma jets emerging into ambient air and helium  

Microsoft Academic Search

An investigation of atmospheric pressure helium plasma jets emerging into ambient air and helium was carried out with the aim of shedding light on the mechanism for the formation of extended plasma plumes. By electron multiplying charge coupled device imaging, it is shown that the geometrical shape of the jet in ambient helium is not an arrow-like shape as that

Wen-Chao Zhu; Qing Li; Xi-Ming Zhu; Yi-Kang Pu

2009-01-01

429

An atmospheric pressure quasiuniform planar plasma jet generated by using a dielectric barrier configuration  

Microsoft Academic Search

A stable nonthermal quasiuniform planar plasma jet, originating from a planar dielectric duct with a rectangular exit and issuing into ambient air at atmospheric pressure, is reported in the present work. Current-voltage characteristics, one discharge current pulse per sinusoidal half voltage cycle, show that the discharge is not filamentary. Its spatial uniformity in the transverse direction is shown to be

Qing Li; Hidemasa Takana; Yi-Kang Pu; Hideya Nishiyama

2011-01-01

430

Numerical Simulation of Downstream Kinetics of an Atmospheric-Pressure Nitrogen Plasma Jet  

Microsoft Academic Search

We report the results of the numerical simulation of an atmospheric-pressure nitrogen plasma jet with the focus on the downstream kinetics. The goal is to assess the effect of ambient air on the spatial profile of reactive species densities of the plasma jet. The modeling results show that oxygen readily enters the jet downstream, and the excited-state nitrogen densities decrease

I-Hung Tsai; Cheng-Che Hsu

2010-01-01

431

Ozone generation in an atmospheric pressure micro-plasma jet in air  

Microsoft Academic Search

Summary form only given. Microhollow cathode discharges (MHCDs) offer the possibility to generate non-thermal plasmas in atmospheric pressure gases, including air, by relatively simple means. The MHCD plasma results from a direct current discharge between two molybdenum electrodes (0.25 mm thick) that are separated by an alumina insulator of the same thickness. A tapered discharge channel is drilled through all

A.-A. H. Mohamed; S. Suddala; M. A. Malik; K. H. Schoenbach

2004-01-01

432

Effects of gas flow rate on the length of atmospheric pressure nonequilibrium plasma jets  

Microsoft Academic Search

Effects of gas flow rate on the length of atmospheric pressure plasma jets have been investigated using a capillary dielectric barrier discharge configuration. For the discharge in only downstream region, three distinguishable modes of plasma jet length versus argon gas flow rate, namely, laminar, transition, and turbulent jet mode, have been identified. For the case of discharge in both downstream

Qing Li; Jiang-Tao Li; Wen-Chao Zhu; Xi-Ming Zhu; Yi-Kang Pu

2009-01-01

433

Droplet Striations Formed in a 900MHz Microwave Argon Atmospheric-Pressure Plasma Jet  

Microsoft Academic Search

Unique striations were observed in the formation of 900-MHz microwave argon atmospheric-pressure plasma jet in air. The striated patterns are easily observed even with the naked eyes at a flow rate of above 3 slm and an input power of below 3 W. Moreover, the striated patterns, which were associated with shortening in the plasma jet length, are obtained by

Sung Kil Kang; Abdel-Aleam H. Mohamed; Hyun Wook Lee; Jae Koo Lee

2011-01-01

434

Inactivation of Salmonella Enteritidis PT 30 on Almonds with a Fluidized Bed Atmospheric Pressure Plasma  

E-print Network

Inactivation of Salmonella Enteritidis PT 30 on Almonds with a Fluidized Bed Atmospheric Pressure for the treatment of Salmonella Enteritidis PT 30 on almonds. Each almond sample was spot inoculated with 10 µl is not conducive for microorganisms to multiply. Salmonella however can survive for extended periods under

Heller, Barbara

435

Influences of gas flow on atmospheric pressure glow discharge in helium  

Microsoft Academic Search

Atmospheric pressure glow discharge (APGD) was produced in a 5-mm helium gap between two plane-parallel electrodes of 50 mm in diameter, each covered by a 1-mm thick quartz plate. The influence of the helium gas flowing in parallel through the helium gap on APGD was studied. The helium flow rate varies up to 12 liter per minute, corresponding to helium

H. Luo; Z. Liang; B. Lv; X. Wang; Z. Guan; L. Wang

2008-01-01

436

Photosynthesis and Growth Response of Almond to Increased Atmospheric Ozone Partial Pressures1  

Microsoft Academic Search

Uniform nursery stock of five almond cultivars (Prunus dulcis (Mill) D.A. Webb syn. P. amygdalus Batsch, ev. Butte, Carmel, Mission, Nonpareil, and Sonora) propagated on peach (P. domestiea L. Batsch.) rootstock were exposed to three different atmospheric ozone (03) par- tial pressures. The trees were planted in open-top fumigation cham- bers on 19 Apr. 1989 at the University of California

W. A. Retzlaff; T. M. DeJong; L. E. Williams

1992-01-01

437

Bacterial inactivation using atmospheric pressure single pin electrode microplasma jet with a ground ring  

Microsoft Academic Search

Bacterial inactivation experiment was performed using atmospheric pressure microplasma jets driven by radio-frequency wave of 13.56 MHz and by low frequency wave of several kilohertz. With addition of a ground ring electrode, the discharge current, the optical emission intensities from reactive radicals, and the sterilization efficiency were enhanced significantly. When oxygen gas was added to helium at the flow rate

Sun Ja Kim; T. H. Chung; S. H. Bae; S. H. Leem

2009-01-01

438

Radio-Frequency Glow Discharges of Different Gases Using Bare Metallic Electrodes at Atmospheric Pressure  

Microsoft Academic Search

The images of the atmospheric-pressure glow discharges driven by the radio-frequency power supply using He, Ar, N2, O2, air, or their mixture as the primary plasma-working gas are presented in this paper. The plasma jet, produced using the planar-type plasma generator behaving like a \\

He-Ping Li; Guo Li; Sen Wang; Pei-Si Le; Cheng-Yu Bao

2008-01-01

439

Comparison of an atmospheric pressure, radio-frequency discharge operating in the ? and ? modes  

Microsoft Academic Search

The ? and ? modes of an atmospheric pressure, radio-frequency plasma have been investigated. The plasma source consisted of two parallel electrodes that were fed with helium and 0.4 vol% nitrogen. The transition from ? to ? was accompanied by a 40% drop in voltage, a 12% decrease in current and a surge in power density from 25 to 2083

X Yang; M Moravej; G R Nowling; S E Babayan; J Panelon; J P Chang; R F Hicks

2005-01-01

440

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

NASA Astrophysics Data System (ADS)

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, Shou-Zhe; Wang, Kun; Zhang, Yutao

2006-09-01

441

Discharge phenomena of an atmospheric pressure radio-frequency capacitive plasma source  

NASA Astrophysics Data System (ADS)

Discharge phenomena of a nonthermal atmospheric pressure plasma source have been studied. An atmospheric pressure plasma jet (APPJ) operates using rf power and produces a stable homogeneous discharge at atmospheric pressure. After breakdown, the APPJ operation is divided into two regimes, a "normal" operating mode when the discharge is stable and homogeneous, and a "failure" mode when the discharge converts into a filamentary arc. Current and voltage (I-V) characteristics and spatially resolved emission intensity profiles have been measured during the normal operating mode. These measurements show that the APPJ produces an alpha (?) mode rf capacitive discharge. Based upon a dimensional analysis using the observed I-V characteristics, a rough estimate is made for plasma density of 3×1011cm-3 and an electron temperature of 2 eV. In addition, the gas temperature of 120 °C has been spectroscopically measured inside the discharge. These plasma parameters indicate that the APPJ shows promise for various materials applications as it can produce substantial amounts of reactive species and avoid thermal damages, while having the advantage of atmospheric pressure operation.

Park, Jaeyoung; Henins, I.; Herrmann, H. W.; Selwyn, G. S.; Hicks, R. F.

2001-01-01

442

Study on the reforming of alcohols in a surface wave discharge (SWD) at atmospheric pressure  

Microsoft Academic Search

Surface wave plasma at atmospheric pressure has been used to produce the decomposition of the alcohol molecules introduced into it, in order to obtain hydrogen. Four alcohols, methanol, ethanol, propanol and butanol, have been used for this purpose. Optical emission spectroscopy was the tool used to analyse the radiation emitted by the plasma. Hydrogen atoms and other species such as

M. Jiménez; C. Yubero; M. D. Calzada

2008-01-01

443

Improvements in the dyeability of polyester fabrics by atmospheric pressure oxygen plasma treatment  

Microsoft Academic Search

Polyester has been widely used as an apparel and technical textile material in the form of fibers, films and plastics due to its excellent mechanical and physical properties. However, its poor surface properties have limited its end?use versatility. In this study, the surface of a polyester fabric was modified by atmospheric pressure plasma treatment with oxygen under different operating conditions

M. M. Kamel; M. M. El Zawahry; H. Helmy; M. A. Eid

2011-01-01

444

Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals from sage leaves  

E-print Network

Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals) for MSI of phytochemicals in sage (Salvia officinalis) leaves. METHODS: Sage leaves were studied by LAAPPI and nonpolar compounds, such as phytochemicals, directly from complex biological samples, and it can provide

Vertes, Akos

445

Collision-Induced Dissociation Analysis of Negative Atmospheric Ion Adducts in Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Collision-induced dissociation (CID) experiments were performed on atmospheric ion adducts [M + R]- formed between various types of organic compounds M and atmospheric negative ions R- [such as O2 -, HCO3 -, COO-(COOH), NO2 -, NO3 -, and NO3 -(HNO3)] in negative-ion mode atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. All of the [M + R]- adducts were fragmented to form deprotonated analytes [M - H]- and/or atmospheric ions R-, whose intensities in the CID spectra were dependent on the proton affinities of the [M - H]- and R- fragments. Precursor ions [M + R]- for which R- have higher proton affinities than [M - H]- formed [M - H]- as the dominant product. Furthermore, the CID of the adducts with HCO3 - and NO3 -(HNO3) led to other product ions such as [M + HO]- and NO3 -, respectively. The fragmentation behavior of [M + R]- for each R- observed was independent of analyte type (e.g., whether the analyte was aliphatic or aromatic, or possessed certain functional groups).

Sekimoto, Kanako; Takayama, Mitsuo

2013-05-01

446

Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma  

SciTech Connect

We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n{sub plu}, which is estimated from the current and the drift velocity, and the gas flow velocity v{sub gas} is examined. It is found that the dependence of the density on the gas flow velocity has relations of n{sub plu} ? log(v{sub gas}). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity.

Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)] [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)

2014-04-15

447

Low-pressure and atmospheric pressure plasma polymerized silica-like films as primers for adhesive bonding of aluminum  

NASA Astrophysics Data System (ADS)

Plasma processes, including plasma etching and plasma polymerization, were investigated for the pretreatment of aluminum prior to structural adhesive bonding. Since native oxides of aluminum are unstable in the presence of moisture at elevated temperature, surface engineering processes must usually be applied to aluminum prior to adhesive bonding to produce oxides that are stable. Plasma processes are attractive for surface engineering since they take place in the gas phase and do not produce effluents that are difficult to dispose off. Reactive species that are generated in plasmas have relatively short lifetimes and form inert products. The objective of this work was to develop plasma etching and plasma polymerization as environmentally compatible processes for surface engineering of aluminum. Plasma polymerized silica-like films of thickness less than 200 nm were deposited on pretreated aluminum substrates using hexamethyldisiloxane (HMDSO) as the "monomer" and oxygen as a "co-reactant" in low-pressure RF-powered (13.6 MHz) reactor. Recently, plasma deposition at atmospheric pressure has become a promising technology because they do not require vacuum systems, can be applied to large objects with complex shapes, and adapted easily for continuous processing. Therefore, atmospheric pressure plasma processes were investigated and compared with their more traditional counterparts, low-pressure plasmas. Molecular structure and morphology of the plasma polymerized films were determined using surface analysis techniques such as X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The effectiveness of plasma etching and plasma polymerization as surface engineering processes for aluminum were probed by determining the initial strength and durability of aluminum/epoxy lap joints prepared from substrates that were plasma pretreated, coated with silica-like film, and then bonded together using a 1-part epoxy adhesive. The durability of joints was evaluated using a "stressed durability test" which involved applying a static load to joints, exposing them to a cyclically varying, corrosive environment, and determining the number of cycles required to produce failure. Atmospheric pressure plasma polymerized HMDSO films exhibit RAIR spectra with prominent features similar to those observed for the low-pressure plasma films. These films had less than 7% carbon, revealing the films to be silica-like in nature. Durability results show that reducing plasma pretreatment of aluminum substrates was better compared to oxygen plasma pretreatment. Joints prepared from aluminum substrates that were acid etched, and then primed with silica-like film had exceptional durability. Durability of these joints was related to the acid etching, which formed a uniform and dense aluminum oxide structure with low magnesium content and high surface topography, and to the primer film which prevented hydration of the oxide. Also, joints prepared from substrates that were atmospheric pressure plasma pretreated exhibited better durability compared to similar joints prepared from substrates that were pretreated in low-pressure reactor. These results show that the atmospheric pressure plasma pretreatment have potential as pretreatment processes that can be applied to metals such as aluminum prior to finishing operations.

Gupta, Munish

2007-12-01

448

Detection of atmospheric pressure loading using very long baseline interferometry measurements  

NASA Technical Reports Server (NTRS)

Loading of the Earth by the temporal redistribution of global atmospheric mass is likely to displace the positions of geodetic monuments by tens of millimeters both vertically and horizontally. Estimates of these displacements are determined by convolving National Meteorological Center (NMC) global values of atmospheric surface pressure with Farrell's elastic Green's functions. An analysis of the distances between radio telescopes determined by very long baseline interferometry (VLBI) between 1984 and 1992 reveals that in many of the cases studied there is a significant contribution to baseline length change due to atmospheric pressure loading. Our analysis covers intersite distances of between 1000 and 10,000 km and is restricted to those baselines measured more than 100 times. Accounting for the load effects (after first removing a best fit slope) reduces the weighted root-mean-square (WRMS) scatter of the baseline length residuals on 11 of the 22 baselines investigated. The slight degradation observed in the WRMS scatter on the remaining baselines is largely consistent with the expected statistical fluctuations when a small correction is applied to a data set having a much larger random noise. The results from all baselines are consistent with approximately 60% of the computed pressure contribution being present in the VLBI length determinations. Site dependent coefficients determined by fitting local pressure to the theoretical radial displacement are found to reproduce the deformation caused by the regional pressure to within 25% for most inland sites. The coefficients are less reliable at near coastal and island stations.

Vandam, T. M.; Herring, T. A.

1994-01-01

449

Growth of a Bacterium Under a High-Pressure Oxy-Helium Atmosphere  

PubMed Central

Growth of a barotolerant marine organism, EP-4, in a glutamate medium equilibrated with an oxy-helium atmosphere at 500 atmospheres (atm; total pressure) (20°C) was compared with control cultures incubated at hydrostatic pressures of 1 and 500 atm. Relative to the 1-atm control culture, incubation of EP-4 at 500 atm in the absence of an atmosphere resulted in an approximately fivefold reduction in the growth rate and a significant but time variant reduction in the rate constants for the incorporation of substrate into cell material and respiration. Distinct from the pressurized control and separate from potential effects of dissolution of helium upon decompression of subsamples, exposure of the organism to high-pressure oxy-helium resulted in either a loss of viability of a large fraction of the cells or the arrest of growth for one-third of the experimental period. After these initial effects, however, the culture grew exponentially at a rate which was three times greater than the 500-atm control culture. The rate constant for the incorporation of substrate into cell material was also enhanced twofold in the presence of high-pressure oxy-helium. Dissolved oxygen was well controlled in all of the cultures, minimizing any potential toxic effects of this gas. PMID:16345337

Taylor, Craig D.

1979-01-01

450

A dielectric-barrier discharge enhanced plasma brush array at atmospheric pressure  

SciTech Connect

This study developed a large volume cold atmospheric plasma brush array, which was enhanced by a dielectric barrier discharge by integrating a pair of DC glow discharge in parallel. A platinum sheet electrode was placed in the middle of the discharge chamber, which effectively reduced the breakdown voltage and working voltage. Emission spectroscopy diagnosis indicated that many excited argon atoms were distributed almost symmetrically in the lateral direction of the plasma. The concentration variations of reactive species relative to the gas flow rate and discharge current were also examined.

Li Xuemei; Zhan Xuefang; Yuan Xin; Zhao Zhongjun; Yan Yanyue; Duan Yixiang [Research Center of Analytical Instrumentation, Analytical Testing Center, College of Chemistry, Sichuan University, Chengdu (China); Tang Jie [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an (China)

2013-07-15

451

Airborne and ground based lidar measurements of the atmospheric pressure profile  

NASA Technical Reports Server (NTRS)

The first high accuracy remote measurements of the atmospheric pressure profile have been made. The measurements were made with a differential absorption lidar system that utilizes tunable alexandrite lasers. The absorption in the trough between two lines in the oxygen A-band near 760 nm was used for probing the atmosphere. Measurements of the two-dimensional structure of the pressure field were made in the troposphere from an aircraft looking down. Also, measurements of the one-dimensional structure were made from the ground looking up. Typical pressure accuracies for the aircraft measurements were 1.5-2 mbar with a 30-m vertical resolution and a 100-shot average (20 s), which corresponds to a 2-km horizontal resolution. Typical accuracies for the upward viewing ground based measurements were 2.0 mbar for a 30-m resolution and a 100-shot average.

Korb, C. Laurence; Schwemmer, Geary K.; Dombrowski, Mark; Weng, Chi Y.

1989-01-01

452

LIF diagnostics of hydroxyl radical in atmospheric pressure He-H2O dielectric barrier discharges  

NASA Astrophysics Data System (ADS)

In this paper we present laser induced fluorescence (LIF) measurements of OH relative density in a He-H2O atmospheric pressure dielectric barrier discharge, with an estimation of the absolute density based on the quantitative analysis of the LIF signal and on the decay of OH density in the post-discharge. The possible interference of H2O2 photo-dissociation is discussed and finally excluded. Densities of the order of 1013 cm-3 have been estimated in mixtures with water vapour content ranging from 2.3 to 23 Torr partial pressure. LIF diagnostic characteristics and sensitivity in the OH case at atmospheric pressure are discussed in comparison with absorption techniques.

Dilecce, G.; Ambrico, P. F.; Simek, M.; De Benedictis, S.

2012-04-01

453

Spectral scaling of static pressure fluctuations in the atmospheric surface layer: The interaction between large and small scales  

E-print Network

Spectral scaling of static pressure fluctuations in the atmospheric surface layer: The interaction, University of Iowa, Iowa City, Iowa 52242 Received 17 March 1997; accepted 2 February 1998 Static pressure fluctuations measured in the atmospheric surface layer over a grass covered forest clearing are studied

Katul, Gabriel

454

Comparison of Sterilizing Effect of Nonequilibrium Atmospheric-Pressure He\\/O2 and Ar\\/O2 Plasma Jets  

Microsoft Academic Search

The sterilizing effect of the non-equilibrium atmospheric pressure plasma jet by applying it to the Bacillus subtilis spores is invesigated. A stable glow discharge in argon or helium gas fed with active gas (oxygen), was generated in the coaxial cylindrical reactor powered by the radio-frequency power supply at atmospheric pressure. The experimental results indicated that the efficiency of killing spores

Shouzhe Li; Jinpyo Lim

2008-01-01

455

Splitting and Mixing of High-Velocity Ionization-Wave-Sustained Atmospheric-Pressure Plasmas Generated With a Plasma Gun  

Microsoft Academic Search

The nanosecond imaging of high-velocity ionization- wave-generated plasmas using a plasma gun is presented. A circu- lar glass pipe is used to study the splitting, the propagation, and the mixing of atmospheric-pressure plasma streams ensuing from a single dielectric-barrier-discharge reactor. Index Terms—Atmospheric-pressure plasmas, gas discharge devices.

Vanessa Sarron; Eric Robert; Sébastien Dozias; Marc Vandamme; Delphine Ries; Jean Michel Pouvesle

2011-01-01

456

Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes  

PubMed Central

Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We postulate that the observed behavioral modifications, especially under decreasing barometric pressure would reduce the probability of injury or death under adverse weather conditions. PMID:24098362

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

2013-01-01

457

Heat transport in the marine atmospheric boundary layer during an intense cold air outbreak  

NASA Technical Reports Server (NTRS)

The generation of the virtual heat flux in the convective MABL associated with the January 28, 1986 intense cold air airbreak offshore of the Carolinas is studied. A technique based on the joint frequency distribution of the virtual potential temperature and vertical motion (Mahrt and Paumier, 1984) is used. The results suggest that, if buoyancy is mainly driven by the temperature flux, the physical processes for generating buoyancy flux are about the same for boundary layers over land and ocean, even with different convective regimes.

Chou, Shu-Hsien; Zimmerman, Jeffrey

1988-01-01

458

The Changing Cold Regions Network: Atmospheric, Cryospheric, Ecological and Hydrological Change in the Saskatchewan and Mackenzie River Basins, Canada (Invited)  

NASA Astrophysics Data System (ADS)

The cold interior of Northwestern Canada has one of the world's most extreme and varied climates and, as with other regions across the Arctic, is experiencing rapid environmental change. The Changing Cold Regions Network (CCRN) is a new Canadian research network devoted to addressing key challenges and globally-important issues facing the Arctic by improving the understanding of past and ongoing changes in climate, land, vegetation, and water, and predicting their future integrated responses, with a geographic focus on the Saskatchewan and Mackenzie River Basins. The network is funded for 5 years (2013-18) by the Natural Sciences and Engineering Research Council of Canada, and combines the unique expertise of 36 Canadian scientists representin