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1

Optical Diagnostics On Cold Atmospheric Pressure Plasmas  

NASA Astrophysics Data System (ADS)

Cold atmospheric pressure plasma jets promise high potential for temperature sensitive surface treatments in biomedicine, see e.g. Stoffels et al. (2006). Stable homogeneous low temperature plasma operation is achieved by using helium feed gas and applying radio frequency excitation. Small admixtures of molecular oxygen to the feed gas lead to the efficient generation of highly reactive oxygen radicals. A quantification of these radical densities and fluxes is not only vital for the plasma source development and fundamental understanding but crucial for the risk benefit analysis in biomedical applications. Diagnostics of atmospheric pressure plasmas are extremely challenging due to small confining structures and the collision dominated high pressure environment demanding exceptionally high spatial and temporal resolution down to microns and picoseconds. The most promising approach is active combination of advanced optical techniques and numerical simulations. Diagnostic based modelling as a method to determine absolute atomic oxygen ground state densities inside such atmospheric pressure plasmas is proposed, see e.g. Niemi et al. (2009). A one-dimensional numerical simulation yields the spatial and temporal electron dynamics and subsequently the excitation efficiency of optical emission lines which intensities are measured temporally integrated. The population dynamics of the O 3p3P (? = 844 nm) atomic oxygen state is governed by direct electron impact excitation, dissociative excitation, radiation losses, and collisional induced quenching. Absolute atomic oxygen densities are obtained through comparison with the Ar 2p1 (? = 750.4 nm) state. Results for spatial profiles and power variations are presented. An excellent quantitative agreement with independent two-photon absorption laser-induced fluorescence measurements from Knacke et al. (2008) is found.

Niemi, K.; Waskoenig, J.; Graham L. M.; Gans, T.

2010-07-01

2

Cold plasma brush generated at atmospheric pressure  

SciTech Connect

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

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

2007-01-15

3

Cold atmospheric pressure air plasma jet for medical applications  

SciTech Connect

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

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

2008-06-16

4

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

5

Atmospheric pressure cold plasma as an antifungal therapy  

NASA Astrophysics Data System (ADS)

A microhollow cathode based, direct-current, atmospheric pressure, He/O2 (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; Sun, Yi; Wu, Haiyan; Zhu, Weidong; Lopez, Jose L.; Liu, Wei; Zhang, Jue; Li, Ruoyu; Fang, Jing

2011-01-01

6

Cold atmospheric pressure plasma jet interactions with plasmid DNA  

SciTech Connect

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

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

2011-01-24

7

Pulsed Atmospheric-Pressure Cold Plasma for Endodontic Disinfection  

Microsoft Academic Search

A new plasma dental probe (PDP), powered with 4-6-kV ~100-ns electric pulses at repetition rates of up to 2 kHz, generates a room-temperature > 2-cm-long ~2-mm-diameter plasma plume at ambient atmospheric pressure. The shape of the plasma plume depends on the gas flow rate and the pulse voltage. Growth of Bacillus atrophaeus on nutrient agar plates is completely inhibited by

Chunqi Jiang; Meng-Tse Chen; Christoph Schaudinn; Amita Gorur; P. Thomas Vernier; J. William Costerton; David E. Jaramillo; Parish P. Sedghizadeh; Martin A. Gundersen

2009-01-01

8

Cold atmospheric pressure gas plasma enhances the wear performance of ultra-high molecular weight polyethylene.  

PubMed

Ultra-high molecular weight polyethylene (UHMWPE) is frequently employed in joint replacements because of its high biocompatibility; however, this material does not exhibit particularly strong wear performance, thus potentially reducing the longevity of such devices. Numerous techniques have been investigated to increase the resistance to wear of UHMWPE, but they are all based on expensive machinery and require a high level of safety precautions. Cold atmospheric pressure gas plasma treatment is an inexpensive process that has been used as a surface modification method and as a sterilization technique. We demonstrate for the first time that a helium/oxygen cold atmospheric pressure gas plasma can be used to enhance the wear performance of UHMWPE without affecting the cytocompatibility of the material. The exposure to a cold atmospheric pressure gas plasma results in a greater level of crosslinking of the polyethylene chains. As a consequence of the higher crosslinking, the material stiffness of the treated surface is increased. PMID:22202910

Perni, Stefano; Kong, Michael G; Prokopovich, Polina

2012-03-01

9

ANTIMICROBIAL EFFICACY OF COLD ATMOSPHERIC PRESSURE PLASMA APPLIED TO INOCULATED FOOD SURFACES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cold, atmospheric pressure plasma (CAPP) has previously been shown to effectively eliminate bacteria, including human pathogens, from inert surfaces. A series of experiments were conducted to evaluate CAPP efficacy on food products that represent important classes of surfaces for potential treatment...

10

Disinfection of Ocular Cells and Tissues by Atmospheric-Pressure Cold Plasma  

Microsoft Academic Search

BackgroundLow temperature plasmas have been proposed in medicine as agents for tissue disinfection and have received increasing attention due to the frequency of bacterial resistance to antibiotics. This study explored whether atmospheric-pressure cold plasma (APCP) generated by a new portable device that ionizes a flow of helium gas can inactivate ocular pathogens without causing significant tissue damage.Methodology\\/Principal FindingsWe tested the

Paola Brun; Maria Vono; Paola Venier; Elena Tarricone; Velika Deligianni; Emilio Martines; Matteo Zuin; Silvia Spagnolo; Roberto Cavazzana; Romilda Cardin; Ignazio Castagliuolo; Alvise La Gloria Valerio; Andrea Leonardi

2012-01-01

11

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

12

A dominant role of oxygen additive on cold atmospheric-pressure He + O2 plasmas  

NASA Astrophysics Data System (ADS)

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 [O2] > ˜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 [O2] 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 [O2] = 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 O2-. 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; Rong, Mingzhe; Wang, Xiaohua; Kong, Michael G.

2014-08-01

13

Disinfection of Ocular Cells and Tissues by Atmospheric-Pressure Cold Plasma  

PubMed Central

Background Low temperature plasmas have been proposed in medicine as agents for tissue disinfection and have received increasing attention due to the frequency of bacterial resistance to antibiotics. This study explored whether atmospheric-pressure cold plasma (APCP) generated by a new portable device that ionizes a flow of helium gas can inactivate ocular pathogens without causing significant tissue damage. Methodology/Principal Findings We tested the APCP effects on cultured Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus and Herpes simplex virus-1, ocular cells (conjunctival fibroblasts and keratocytes) and ex-vivo corneas. Exposure to APCP for 0.5 to 5 minutes significantly reduced microbial viability (colony-forming units) but not human cell viability (MTT assay, FACS and Tunel analysis) or the number of HSV-1 plaque-forming units. Increased levels of intracellular reactive oxygen species (ROS) in exposed microorganisms and cells were found using a FACS-activated 2?,7?-dichlorofluorescein diacetate probe. Immunoassays demonstrated no induction of thymine dimers in cell cultures and corneal tissues. A transient increased expression of 8-OHdG, genes and proteins related to oxidative stress (OGG1, GPX, NFE2L2), was determined in ocular cells and corneas by HPLC, qRT-PCR and Western blot analysis. Conclusions A short application of APCP appears to be an efficient and rapid ocular disinfectant for bacteria and fungi without significant damage on ocular cells and tissues, although the treatment of conjunctival fibroblasts and keratocytes caused a time-restricted generation of intracellular ROS and oxidative stress-related responses. PMID:22432007

Vono, Maria; Venier, Paola; Tarricone, Elena; Deligianni, Velika; Martines, Emilio; Zuin, Matteo; Spagnolo, Silvia; Cavazzana, Roberto; Cardin, Romilda; Castagliuolo, Ignazio; La Gloria Valerio, Alvise; Leonardi, Andrea

2012-01-01

14

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

15

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

16

80 mm-wide cold atmospheric-pressure plasma generated by two parallel but horizontally separated electrodes  

NASA Astrophysics Data System (ADS)

80 mm-wide helium cold atmospheric-pressure plasma (CAPP) was generated via two parallel but horizontally separated electrodes. The CAPP is considered to be essentially a positive streamer, and the separated electrodes suppress arc transition of the CAPP. Both the electrodes' distance and He flow rate at medium values favor plasma expulsion. The optical emission spectra of the CAPP demonstrate that He related species are dominant inside the plasma generator, while the main species downstream are radicals of OH, atomic O, ?-NO and N2 related species. In addition, the gas temperature of the CAPP simulated OH line (309 nm) is approximately room temperature.

Chen, Qiang; Ichiki, Takanori

2015-04-01

17

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

18

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

PubMed Central

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.

2013-01-01

19

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

NASA Astrophysics Data System (ADS)

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

Niemi, K.; O'Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O'Connell, D.; Gans, T.

2012-05-01

20

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

21

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

22

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

23

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

24

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

PubMed

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

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

2014-08-01

25

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

NASA Astrophysics Data System (ADS)

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

Pedrow, Patrick; Fernandez, Sulmer; Pitts, Marvin

2008-10-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

27

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

28

On the design and characterization of a new cold atmospheric pressure plasma jet and its applications on cancer cells treatment.  

PubMed

In this paper, a new configuration of a cold atmospheric pressure plasma jet has been designed and constructed. Poly-methyl-methacrylate was used as a new dielectric in this configuration which in comparison to other dielectrics is inexpensive, more resistant against break, and also more shapeable. Then, the plasma jet parameters such as plume temperature, rotational and vibrational temperatures, power, electrical behavior (voltage and current profile), electron density, and the produced reactive species were characterized. In order to determine the jet temperature and the amount of reactive species, effects of applied voltage, gas flow rate, and distance from the nozzle were studied. The power of the jet was specified using Lissajous curve approach. The plume temperature of the plasma jet was about the room temperature. Optical emission spectroscopy determined the type of reactive species, and also electron density and its corresponding plasma frequency (?6.4(?) ×(?)10(13?)cm(-3) and 4.52(?) ×(?)10(11?)Hz). Because of producing different reactive species, the device can be used in different applications, especially in plasma medicine. Thus, 4T1 cancer cells were treated using this plasma jet. The results showed that this plasma jet has a great potential to kill one of the most aggressive and resistant cancerous cell lines. PMID:25908593

Akhlaghi, Morteza; Rajayi, Hajar; Mashayekh, Amir Shahriar; Khani, Mohammadreza; Hassan, Zuhair Mohammad; Shokri, Babak

2015-01-01

29

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

30

1-D fluid model of atmospheric-pressure rf He+O2 cold plasmas: Parametric study and critical evaluation  

NASA Astrophysics Data System (ADS)

In this paper atmospheric-pressure rf He+O2 cold plasmas are studied by means of a 1-D fluid model. 17 species and 60 key reactions selected from a study of 250+ reactions are incorporated in the model. O2+, O3-, and O are the dominant positive ion, negative ion, and reactive oxygen species, respectively. Ground state O is mainly generated by electron induced reactions and quenching of atomic and molecular oxygen metastables, while three-body reactions leading to the formation of O2 and O3 are the main mechanisms responsible for O destruction. The fraction of input power dissipated by ions is ˜20%. For the conditions considered in the study ˜6% of the input power is coupled to ions in the bulk and this amount will increase with increasing electronegativity. Radial and electrode losses of neutral species are in most cases negligible when compared to gas phase processes as these losses are diffusion limited due to the large collisionality of the plasma. The electrode loss rate of neutral species is found to be nearly independent of the surface adsorption probability p for p > 0.001 and therefore plasma dosage can be quantified even if p is not known precisely.

Yang, Aijun; Wang, Xiaohua; Rong, Mingzhe; Liu, Dingxin; Iza, Felipe; Kong, Michael G.

2011-11-01

31

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

SciTech Connect

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

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

2012-06-15

32

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

33

Aircraft Performance: Atmospheric Pressure  

E-print Network

Aircraft Performance: Atmospheric Pressure FAA Handbook of Aeronautical Knowledge Chap 10 #12 ­ 21% Oxygen ­ 1% other gases (argon, helium, etc) · Most oxygen Atmospheric Pressure;High Density Altitude (worse performance) · High elevations · Low atmospheric pressures · High

34

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

35

Repeated applications of cold atmospheric pressure plasma does not induce resistance in Staphylococcus aureus embedded in biofilms  

PubMed Central

Introduction: The increasing microbial resistance against antibiotics complicates the therapy of bacterial infections. Therefore new therapeutic options, particularly those causing no resistance, are of high interest. Cold atmospheric plasma is one possible option to eradicate multidrug resistant microorganisms, and so far no resistance development against physical plasma is known. Method: We tested 6-fold repeated plasma applications on a Staphylococcus aureus strain embedded in biofilm and compared the reduction of the colony forming units between the different treatment periods to asses a possible development of resistance. Result: For all treatment periods, the control biofilms were reduced by plasma in average by 1.7 log10 CFU, and decreased from 7.6 to 5.8 log10 (CFU/cm2) within 5 hours. The results demonstrated that repeated plasma doses not induce resistance or habituation against plasma applied within short time periods. Conclusion: The repeated application of cold plasma is a promising option for the treatment of infected wounds without the risk of development of resistance against plasma. PMID:25285261

Matthes, Rutger; Assadian, Ojan; Kramer, Axel

2014-01-01

36

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

37

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

38

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

39

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

40

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

41

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

42

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

43

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

44

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

45

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

46

Atmospheric durability of polymer-fiber composites in cold climates  

Microsoft Academic Search

1.From an analysis of experimental data obtained in two to three years of natural exposure of fiber-reinforced polymeric composites under cold climatic conditions, the following basic facts have been established: The atmospheric durability of composites based on glass and organic fibers under cold climatic conditions is generally higher than for materials based on carbon fillers; the atmospheric durability of composites

V. N. Bulmanis; G. M. Gunyaev; V. V. Krivonos; G. P. Mashinskaya; V. M. Merkulova; G. I. Milyutin; A. A. Gerasimov; S. A. Kuz'min

1991-01-01

47

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

48

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

49

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

50

Atmospheric composition of cold super-Earths  

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

51

Biomedical applications and diagnostics of atmospheric pressure plasma  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

52

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

53

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

54

Atmospheric pressure femtosecond laser imaging mass spectrometry  

Microsoft Academic Search

We present a novel imaging mass spectrometry technique using femtosecond laser pulses to ionize the sample at atmospheric pressure and without the need of a laser-absorbing matrix. A 10 mum-resolution image of biological tissue is demonstrated.

Yves Coello; Tissa C. Gunaratne; Marcos Dantus

2009-01-01

55

BIOLOGICALAPPLICATIONS OF ATMOSPHERIC PRESSURE DIELECTRIC BARRIER DISCHARGES  

E-print Network

ABSTRACT. A reduction of more than 4 orders of magnitude of survivors was obtained by exposing a Bacillus Stearothermophilus spores - contaminated surface to an atmospheric pressure DBD post-discharge for 20 minutes

Paris-Sud XI, Université de

56

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

57

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

58

Patterns of Atmospheric Circulation Associated with Cold Outbreaks in Southern Amazonia  

NASA Astrophysics Data System (ADS)

This study is based on 202 cold outbreak (friagem) events that occurred in the southern Amazon region during the austral winter months (May to September). For this analysis, 30 years of data were used from the NCEP/CFSR reanalysis, and from minimum temperature and mean sea level pressures observed at surface stations between the years 1979 and 2008. The cold outbreaks caused significant changes in weather conditions in the region due to the sudden decreases in air temperature and rises in surface pressure. The incursion of cold, dry air is a relatively common phenomenon in the tropical region in the months from May to September, and in that sense the purpose of this work is to study the behavior of the regional atmospheric circulation associated with cold events during the austral winter in the city of Vilhena, as well as to identify the essential characteristics of the precursor flow during the three days preceding the cold events in the southern Amazon, through the method of compositing of variables and analysis of the various physical processes responsible for the sharp drop in temperature that determines the cold outbreak. The purpose here is to create a synoptic classification of these events, thus enabling a better understanding of the phenomenon and an improvement in the quality of weather forecasts.

Herdies, D. L.; Ricarte, R. R.

2013-05-01

59

Measuring the atmosphere : temperature, pressure and ozone  

NSDL National Science Digital Library

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

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

2003-01-01

60

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

61

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

62

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.

63

Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry  

E-print Network

Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry Anu Vaikkinen, Washington, DC 20052, United States *S Supporting Information ABSTRACT: In this paper we introduce laser ablation atmo- spheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass

Vertes, Akos

64

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

65

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

66

Effects of cold atmospheric plasmas on adenoviruses in solution  

NASA Astrophysics Data System (ADS)

Experiments were performed with cold atmospheric plasma (CAP) to inactivate adenovirus, a non-enveloped double stranded DNA virus, in solution. The plasma source used was a surface micro-discharge technology operating in air. Various plasma diagnostic measurements and tests were performed in order to determine the efficacy of CAPs and to understand the inactivation mechanism(s). Different stages of the adenovirus ‘life cycle’ were investigated—infectivity and gene expression as well as viral replication and spread. Within 240 s of CAP treatment, inactivation of up to 6 decimal log levels can be achieved.

Zimmermann, J. L.; Dumler, K.; Shimizu, T.; Morfill, G. E.; Wolf, A.; Boxhammer, V.; Schlegel, J.; Gansbacher, B.; Anton, M.

2011-12-01

67

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

68

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

69

Biomedical Applications of the Cold Atmospheric Plasma: Cell Responses  

NASA Astrophysics Data System (ADS)

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

Volotskova, Olga

70

A microwave pressure sounder. [for remote measurement of atmospheric pressure  

NASA Technical Reports Server (NTRS)

A technique for the remote measurement of atmospheric surface pressure will be described. Such measurements could be made from a satellite in polar orbit and would cover many areas for which conventional meteorological data are not available. An active microwave instrument is used to measure the strength of return echoes from the ocean surface at a number of frequencies near the 60 GHz oxygen absorption band. Factors which affect the accuracy with which surface pressure can be deduced from these measurements will be discussed and an instrument designed to test the method by making measurements from an aircraft will be described.

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

1981-01-01

71

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

72

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

73

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

74

Use of cold atmospheric plasma in the treatment of cancer.  

PubMed

Cold atmospheric plasma (CAP) is an emerging modality for the treatment of solid tumors. In-vitro experiments have demonstrated that with increasing doses of plasma, tumor cells assays display decreased cell viability. CAP is theorized to induce tumor cells into apoptosis via multiple pathways including reactive oxygen and nitrogen species as well as cell cycle disruption. Studies have shown CAP treatment can decrease mouse model glioblastoma multiforme tumor volume by 56%, increase life span by 60%, and maintain up to 85% viability of normal cells. Emerging evidence suggests that CAP is a viable in-vivo treatment for a number of tumors, including glioblastoma, as it appears to selectively induce tumor cell death while noncancerous cells remain viable. PMID:25791295

Babington, Parker; Rajjoub, Kenan; Canady, Jerome; Siu, Alan; Keidar, Michael; Sherman, Jonathan H

2015-01-01

75

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

76

Apoptosis in vascular cells induced by cold atmospheric plasma treatment  

NASA Astrophysics Data System (ADS)

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

Sladek, Raymond; Stoffels, Eva

2006-10-01

77

A RF Discharge in Argon at Atmospheric Pressure  

Microsoft Academic Search

A dual chamber dischrage is used to create an atmospheric pressure plasma in Argon. The discharge consists of two chambers: one at low pressure (few Torrs) and the other at atmospheric pressure. The chambers are seperated by fused silica window. A RF source(13.56 MHz) is used to create a discharge first in the low pressure chamber which is filled with

Shirshak Dhali; Navin Muthuswamy; Bakul Dave

2001-01-01

78

Chaos in atmospheric-pressure plasma jets  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

79

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

PubMed Central

Cold Atmospheric Plasma is an ionized gas that has recently been extensively studied by researchers as a possible therapy in dentistry and oncology. Several different gases can be used to produce Cold Atmospheric Plasma such as Helium, Argon, Nitrogen, Heliox, and air. There are many methods of production by which cold atmospheric plasma is created. Each unique method can be used in different biomedical areas. In dentistry, researchers have mostly investigated the antimicrobial effects produced by plasma as a means to remove dental biofilms and eradicate oral pathogens. It has been shown that reactive oxidative species, charged particles, and UV photons play the main role. Cold Atmospheric Plasma has also found a minor, but important role in tooth whitening and composite restoration. Furthermore, it has been demonstrated that Cold Atmospheric Plasma induces apoptosis, necrosis, cell detachment, and senescence by disrupting the S phase of cell replication in tumor cells. This unique finding opens up its potential therapy in oncology. PMID:24083477

2013-01-01

80

Demixing in Atmospheric-Pressure Arcs  

NASA Astrophysics Data System (ADS)

Most atmospheric-pressure arcs of industrial interest contain mixtures of gases. In arc welding, for example, mixtures of argon with helium, hydrogen, carbon dioxide or oxygen are used. Demixing is a diffusion-driven phenomenon that leads to the partial separation of the different chemical elements present in such arcs. Typically the chemical elements with lower mass and higher ionization energies are concentrated in the high-temperature regions of the arc. A two-dimensional numerical model of demixing in atmospheric-pressure free burning arcs has been developed.(A. B. Murphy, Phys. Rev. E, 55) (1997) 7473--94; J. Phys. D, 31 (1998) 3383--90. The model incorporates the combined-diffusion-coefficient treatment of diffusion, (A. B. Murphy, Phys. Rev. E, 48) (1993) 3594--604. which allows all species derived from a particular chemical element to be grouped together. Arcs in mixtures of argon with helium, hydrogen, oxygen and nitrogen have been investigated. It is predicted that demixing causes large changes in composition, up to a factor of four compared to a fully-mixed plasma. The predictions have been compared to spectroscopic measurements of argon--nitrogen, argon--helium and argon--hydrogen arcs, with generally good agreement being observed.(A. B. Murphy and K. Hiraoka, J. Phys. D, submitted.) The model has been used to obtain significant physical insights into the importance of the different demixing mechanisms, which include demixing due to partial pressure gradients, demixing due to collisional forces, demixing due to thermal diffusion, and cataphoresis. The model also allows the investigation of the effect of demixing on parameters such as arc temperature and flow, and heat flow to the electrodes. It is found that demixing can significantly alter the latter parameter, which is critical in welding applications.

Murphy, A. B.

2000-10-01

81

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

82

Response of cyanobacteria to low atmosphere pressure  

NASA Astrophysics Data System (ADS)

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

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

83

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

84

Integrin activation by a cold atmospheric plasma jet  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

85

Cold Atmospheric Plasma as an alternative therapy for cancer therapies  

NASA Astrophysics Data System (ADS)

CAP (cold atmospheric plasma) is a technology, which is based on quasi-neutral ionized gas (plasma at low temperatures), which is being evaluated as an alternative or addition to existing cancer therapies. A recent study shows that CAP treatment can cause a significant reduction in tumor size in vivo. Thus the purpose of this study is to begin to identify the mechanism by which cancer cells are killed by CAP, i.e. 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 significant decrease in EdU-signal of DNA-replicating cells. Our data suggest that more tumorigenic cancer cells are better susceptible to CAP treatment.

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

2012-10-01

86

Atmospheric pressure femtosecond laser imaging mass spectrometry.  

PubMed

A novel atmospheric pressure imaging mass spectrometry approach that offers improved lateral resolution (10 microm) using near-infrared femtosecond laser pulses for nonresonant desorption and ionization of sample constituents without the need of a laser-absorbing matrix is demonstrated. As a proof of concept the method was used to image a two-chemical pattern in paper. To demonstrate the ability of the approach to analyze biological tissue, a monolayer of onion epidermis was imaged allowing the chemical visualization of individual cells using mass spectrometry at ambient conditions for the first time. As the spatial resolution is currently limited by the limit of detection of the setup (approximately 500 fmol limit of detection for citric acid), improvements in sensitivity will increase the achievable spatial resolution. PMID:20210322

Coello, Yves; Jones, A Daniel; Gunaratne, Tissa C; Dantus, Marcos

2010-04-01

87

Propagation of an atmospheric pressure plasma plume  

SciTech Connect

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

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

2009-02-15

88

Propagation of an atmospheric pressure plasma plume  

NASA Astrophysics Data System (ADS)

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

Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.

2009-02-01

89

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

90

Ram pressure stripping and the formation of cold fronts  

E-print Network

Chandra and XMM-Newton observations of many clusters reveal sharp discontinuities in the surface brightness, which, unlike shocks, have lower gas temperature on the X-ray brighter side of the discontinuity. For that reason these features are called ``cold fronts''. It is believed that some cold fronts are formed when a subcluster merges with another cluster and the ram pressure of gas flowing outside the subcluster gives the contact discontinuity the characteristic curved shape. While some edges may not arise directly from mergers (e.g., A496, Dupke & White, 2003), this paper focuses on those which arise as contact discontinuities between a merging subcluster and the ambient cluster gas. We argue that the flow of gas past the merging subcluster induces slow motions inside the cloud. These motions transport gas from the central parts of the subcluster towards the interface. Since in a typical cluster or group (even an isothermal one) the entropy of the gas in the central regions is significantly lower than in the outer regions, the transport of the low entropy gas towards the interface and the associated adiabatic expansion makes the gas temperature immediately inside the interface lower than in any other place in the system, thus enhancing the temperature jump across the interface and making the ``tip'' of the contact discontinuity cool. We illustrate this picture with the XMM-Newton gas temperature map of the A3667 cluster.

S. Heinz; E. Churazov; W. Forman; C. Jones; U. G. Briel

2003-08-08

91

[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

92

Cold atmospheric plasma - A new technology for spacecraft component decontamination  

NASA Astrophysics Data System (ADS)

Cold atmospheric plasma (CAP) based on the Surface Micro-Discharge (SMD) technology was investigated for inactivation of different bacteria and endospores. The used technique was developed to serve as an alternative method for the decontamination of spacecraft components based on the COSPAR planetary protection policy where currently the dry heat microbial reduction method is the only applicable way to satisfy the required demands. However it is known, that dry heat can thermally damage sophisticated components installed on the device. Therefore, the development of a low temperature sterilization system is one of the high priority issues for upcoming space missions in the extraterrestrial field. In the study presented here, the vegetative bacteria Escherichia coli and Deinococcus radiodurans and several types of bacterial endospores - including Bacillus atrophaeus, Bacillus safensis, Bacillus megaterium, Bacillus megaterium 2c1 and Bacillus thuringiensis E24 - were inactivated by exposing them indirectly i.e. only to the reactive gases produced by the SMD electrode at room temperature. The results showed a 5 log inactivation for E. coli after 10 min of exposure. In contrast D. radiodurans proved to be more resistant resulting in a reduction of 3 log after exposure of 30 min. More than 6 log reductions were achieved for B. safensis, B. megaterium and B. megaterium 2c1 after 90 min of exposure. Furthermore the applicability of the used CAP system for spacecraft decontamination according to the planetary protection policy was investigated. This included also the investigation of the inactivation homogeneity by the plasma gas, the control of the temperature at the area of interest, the measurement of the O3 density in the treatment region and the detailed investigation of the effects of the exposure on different materials.

Shimizu, Satoshi; Barczyk, Simon; Rettberg, Petra; Shimizu, Tetsuji; Klaempfl, Tobias; Zimmermann, Julia L.; Hoeschen, Till; Linsmeier, Christian; Weber, Peter; Morfill, Gregor E.; Thomas, Hubertus M.

2014-01-01

93

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

94

High frequency atmospheric cold plasma treatment system for materials surface processing  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

95

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

96

April 2007 Cold Wave National Oceanic and Atmospheric Administration  

E-print Network

of the event in concert with crop emergence and tree blooms. Winter wheat across the central Plains and Midwest crops. Several factors made this cold wave more harmful to agricultural interests than similar events, a pattern shift brought this cold Arctic air southward into the central and eastern U.S. This record

97

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

98

FLOWS OF MASS, MOMENTUM AND ENERGY IN THE SOLAR ATMOSPHERE A SOHOORIENTED VIEW OF COLD LOOPS  

E-print Network

5 FLOWS OF MASS, MOMENTUM AND ENERGY IN THE SOLAR ATMOSPHERE A SOHO­ORIENTED VIEW OF COLD LOOPS G long loops ob­ served in several spectral lines by SOHO. In particular an observation made by SOHO are also discussed. The cold EUV loops observed in detail by SOHO instruments can provide information

99

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

100

Cold atmospheric plasma sterilization: from bacteria to biomolecules  

NASA Astrophysics Data System (ADS)

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

Kong, Michael

2009-10-01

101

Atmospheric pressure plasmas: infection control and bacterial responses.  

PubMed

Cold atmospheric pressure plasma (APP) is a recent, cutting-edge antimicrobial treatment. It has the potential to be used as an alternative to traditional treatments such as antibiotics and as a promoter of wound healing, making it a promising tool in a range of biomedical applications with particular importance for combating infections. A number of studies show very promising results for APP-mediated killing of bacteria, including removal of biofilms of pathogenic bacteria such as Pseudomonas aeruginosa. However, the mode of action of APP and the resulting bacterial response are not fully understood. Use of a variety of different plasma-generating devices, different types of plasma gases and different treatment modes makes it challenging to show reproducibility and transferability of results. This review considers some important studies in which APP was used as an antibacterial agent, and specifically those that elucidate its mode of action, with the aim of identifying common bacterial responses to APP exposure. The review has a particular emphasis on mechanisms of interactions of bacterial biofilms with APP. PMID:24637224

Mai-Prochnow, Anne; Murphy, Anthony B; McLean, Keith M; Kong, Michael G; Ostrikov, Kostya Ken

2014-06-01

102

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

103

Atmospheric durability of polymer-fiber composites in cold climates  

Microsoft Academic Search

In evaluating the prospects for using composite materials in the fabrication of structures and end-items that are servicable in regions with cold climates both the economic and technical aspects of the problem must be considered. In the foreign press, even at the start of the 1970s, it was argued that the savings from the use of composites would be particularly

V. N. Bulmanis; G. M. Gunyaev; V. V. Krivonos

1992-01-01

104

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

105

European Cold Winters and the Persistence of Atmospheric Blocking  

NASA Astrophysics Data System (ADS)

Cold winters over Western Europe can often be related to the existence of anomalous circulation patterns that involve prolonged easterly flow. Persistence of these anomalous conditions is crucial, for it takes several days to transport the cold air from Northern and Eastern Europe towards Western Europe. In a few historic cases these anomalous circulation conditions, in which the prevailing westerlies are temporarily 'blocked', existed for more than a month, thereby impacting significantly on regional climate. Climate models are known to have problems representing both frequency and persistence of these so-called blocking events. It is not clear whether increased resolution will solve this problem completely. Here we study the evolution and in particular the persistence of blocking episodes from a potential vorticity perspective. An analysis in terms of potential vorticity is attractive because of its lagrangian conservation properties under adiabatic conditions. Enhanced insight in the blocking dynamics may in turn increase or decrease confidence in current climate models.

de Vries, Hylke; Haarsma, Reindert; Hazeleger, Wilco

2010-05-01

106

Visualization of a Copper Wire Explosion in Atmospheric Pressure Air  

E-print Network

Experimental and computational images of a 90-?m thick copper wire explosion in atmospheric pressure air are presented. A Marx generator is used to produce a pulsed current density into the wire with a maximum rate of rise ...

Jadidian, Jouya

107

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.

108

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

109

On OH production in water containing atmospheric pressure plasmas  

NASA Astrophysics Data System (ADS)

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

Bruggeman, Peter; Schram, Daan C.

2010-08-01

110

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

111

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

112

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

113

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

114

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...

115

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

116

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

117

EPIC 95W Observations of the Eastern Pacific Atmospheric Boundary Layer from the Cold Tongue to the ITCZ  

E-print Network

and Earth Science and Technology, University of Hawaii at Manoa, POST 413, 2525 Correa Road, Honolulu, HIEPIC 95°W Observations of the Eastern Pacific Atmospheric Boundary Layer from the Cold Tongue, with an emphasis on the evolution of the thermodynamic ABL properties from the cold tongue to the cold- advection

Bretherton, Chris

118

The Effects of Cold and Lower Body Negative Pressure on Cardiovascular Homeostasis  

PubMed Central

Purpose. The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables. Methods. Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP. During the 2 trials, the subjects were exposed to cold air (10°C) (COLD) and to ambient temperature (23°C) (AMB). The trials consisted of a 100-minute pre-LBNP period followed by a 20-minute exposure to LBNP and then a 15-minute recovery period. Cardiovascular variables were recorded every 30 minutes using bioimpedance. Results. When LBNP was applied during the AMB trials, stroke volume immediately decreased. During the COLD trial, there was a five-minute delay before the decrease in stroke volume. Heart rate increased immediately after LBNP initiation during the AMB trials but there was a delay in the increase during the COLD trials. That same pattern was followed with mean arterial blood pressures. Cerebral oxygenation was significantly lower throughout the COLD trial as compared to the AMB trials. Six subjects reported symptoms of syncope or presyncope during the AMB trials but there were no reports of symptoms during the COLD trials. Conclusion. From analysis of this data, cold improved the subject's tolerance to LBNP.

Kean, David J.; Peacock, Corey A.; Sanders, Gabriel J.; McDaniel, John; Colvin, Lisa A. C.; Glickman, Ellen L.

2015-01-01

119

Evolution of Marine Atmospheric Boundary Layer Structure across the Cold Tongue-ITCZ Complex  

Microsoft Academic Search

The structure of the marine atmospheric boundary layer (MABL) over the tropical eastern Pacific Ocean is influenced by spatial variations of sea surface temperature (SST) in the region. As the MABL air is advected across a strong SST gradient associated with the cold tongue-ITCZ complex (CTIC), substantial changes occur in the thermodynamic structure, surface fluxes, and cloud properties. This study

Hollis E. Pyatt; Bruce A. Albrecht; Chris Fairall; J. E. Hare; Nicholas Bond; Patrick Minnis; J. Kirk Ayers

2005-01-01

120

Comparative atmospheric corrosion of primary and cold rolled copper in Australia  

Microsoft Academic Search

Atmospheric corrosion tests, according to ASTM G50, have been carried out in Queensland, Australia, at three different sites representing three different environmental conditions. A range of materials including primary copper (electrosheet) and electrolytic tough pitch (traditional cold rolled) copper have been exposed. Data is available for five exposure periods over a three year time span. X-Ray Diffraction has been used

J. D. Nairn; S. G. Skennerton; A. Atrens

2003-01-01

121

Effects of nonthermal atmospheric cold plasma on blueberry native microbiota and sensory attributes  

Technology Transfer Automated Retrieval System (TEKTRAN)

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 120s 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 w...

122

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

123

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

124

Measurement of activated species generated by 60 Hz excited atmospheric pressure Ar plasma in atmospheric gas  

NASA Astrophysics Data System (ADS)

Atmospheric pressure plasmas have a wide field of applications. To improve the performance, it needs to diagnose the behaviors of activated species generated by plasma discharge and to study about the gas-phase reactions in atmospheric pressure. Moreover, plasma treatments are frequently carried out under atmospheric condition without purge gases. In this study, behaviors of activated species generated by the atmospheric pressure plasma under atmospheric condition have been measured by using LIF spectroscopy. Firstly, concentration of the grand state nitrogen monoxide (NO) was measured. The wavelength of laser light for the excitation of NO was 226.3 nm. The fluorescence was observed on A-X(0, 2) band around 247 nm. The AC excited atmospheric pressure plasma with pure Ar gas was generated under atmospheric condition. The flow rate of Ar gas was fixed at 3 slm. The atmospheric condition was the humidity of 40% and ambient temperature of 25 ^oC. Concentration of NO has been measured as a function of distance from a jet slit of plasma head. The length of plasma jet was around 10 mm. The results show that the concentration of NO has a maximum at 10 mm from plasma head, and then decreases. This means that the influence of ambient gases was largest in the edge region of plasma.

Takeda, Keigo; Jolibois, Jerome; Ishikawa, Kenji; Tanaka, Hiromasa; Kano, Hiroyuki; Sekine, Makoto; Hori, Masaru

2012-10-01

125

Is atmospheric pressure change an Independent risk factor for hemoptysis?  

PubMed Central

Objective: Hemoptysis is one of the most important and challenging symptoms in pulmonary medicine. Because of the increased number of patients with hemoptysis in certain periods of the year, we aimed to investigate whether atmospheric changes have an effect on the development of hemoptysis with or without a secondary cause. Methods: The data of patients presenting with hemoptysis between January 2006 and December 2011 were analyzed. Data on the daily atmospheric pressure (hectopascal, hPa), relative humidity (%), and temperature (o C) during that time were obtained. Results: A total of 232 patients with hemoptysis, 145 male (62.5%) and 87 female (37.5%) with an average age of 48.1(±17.6), were admitted to our hospital between 2006 and 2011. The highest admission rates were in the spring season, the highest in May (n=37, 15.9%), and the lowest admission rates were in December (n=10, 4.3%). A statistically significant negative correlation was found between the number of hemoptysis cases and mean atmospheric pressure but no relative humidity or outdoor temperature. Conclusion: Hemoptysis is very much influenced by weather factors; in particular, low atmospheric pressures significantly affect the development of hemoptysis. Fluctuations in atmospheric pressure may also play a role in hemoptysis. PMID:24948987

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

2014-01-01

126

Atmospheric-pressure-plasma nitriding of titanium alloy  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure-plasma nitriding of titanium alloy Ti–6Al–4V has been achieved by using a pulsed-arc plasma jet with a N2/H2 gas mixture, where the plasma jet plume is sprayed onto the titanium surface under atmospheric pressure. We successfully formed a titanium nitride layer on the sample surface. Moreover, the diffusion layer was also formed, the hardness of which was increased from that of as-received titanium. The nitride layer growth was found to be diffusion-controlled, as in other conventional nitriding methods.

Yoshimitsu, Yuki; Ichiki, Ryuta; Kasamura, Kotaro; Yoshida, Masashi; Akamine, Shuichi; Kanazawa, Seiji

2015-03-01

127

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

128

A microwave pressure sounder for the remote measurement of atmospheric surface pressure  

NASA Technical Reports Server (NTRS)

An instrument to measure atmospheric pressure at the Earth's surface from an orbiting satellite is considered. Surface pressure can be deduced from measurements of the transmission of an atmospheric column at several frequencies at the edges of the 60 GHz oxygen absorption band. An active microwave instrument proposed to make these measurements is the subject of a joint UK-US development program to demonstrate its capabilities. The results of an extensive analysis of the potential performance of the instrument are summarized.

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

1980-01-01

129

A helium freeze-out cleaner operating at atmospheric pressure  

Microsoft Academic Search

A low pressure helium purification system has been designed at CERN. The helium gas recovered by means of a set of vacuum pumps from subatmospheric cryogenic circuits is cleaned at purity levels permitting direct re-liquefaction into the main cryo-plant cycle. The gas to be cleaned is close to ambient temperature and atmospheric pressure. It is cooled down to 33K by

J. P. Dauvergne; D. Delikaris; F. Haug; S. Knoops

1994-01-01

130

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

Microsoft Academic Search

We have designed and fabricated a surface micromachined Pirani pressure sensor with an extremely narrow gap between its heater and heatsink (substrate) with superior output linearity in the atmospheric pressure range. The gap size of the device has been reduced to 50 nm by using a layer of PECVD amorphous silicon as a sacrificial layer and a xenon difluoride (XeF2)

Kourosh Khosraviani; Albert M. Leung

2009-01-01

131

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

132

Preparation of nanodiamonds from carbon nanoparticles at atmospheric pressure.  

PubMed

A route for producing diamond nanocrystals is reported in this paper. Li2CO3 containing carbon nanostructures synthesised in molten LiCl were transformed to nanodiamonds by simple heating at atmospheric pressure, far less severe conditions than conventional processes. The method presented offers the possibility of bulk production. PMID:25650151

Kamali, Ali Reza; Fray, Derek J

2015-03-17

133

DC and Pulsed Dielectric Surface Flashover at Atmospheric Pressure  

Microsoft Academic Search

In a wide variety of high-voltage applications surface flashover plays a major role in the system's performance and yet has not been studied in great detail for atmospheric conditions with modern diagnostic tools. Environmental conditions to be considered include pressure, humidity, and gas present in the volume surrounding the dielectric. In order to gain knowledge into the underlying process involved

John T. Krile; Andreas A. Neuber; James C. Dickens; Hermann G. Krompholz

2005-01-01

134

From Submicrosecond to Nanosecond-Pulsed Atmospheric-Pressure Plasmas  

Microsoft Academic Search

We have developed a time-hybrid computational model to study pulsed atmospheric-pressure discharges and compared simulation results with experimental data. Experimental and computational results indicate that increasing the applied voltage results in faster ignition of the discharge and an increase in the mean electron energy, opening the door to tunable plasma chemistry by means of pulse shaping. Above a critical electric

Felipe Iza; James L. Walsh; Michael G. Kong

2009-01-01

135

Ion transport through capillary atmospheric pressure interfaces of mass spectrometers  

Microsoft Academic Search

The transmission efficiency of ions\\/charged droplets traveling through typical atmospheric pressure interfaces (API) of mass spectrometers is investigated to advance the understanding of charge transport in micro capillaries. The charge transfer efficiency for various capillary dimensions and same flow conductance was focused upon. Quantitative measurements of current transmitted through the API and the current lost to the wall of the

Sandilya Venkata Bhaskara Garimella

2009-01-01

136

Atmospheric Pressure Infrared MALDI Imaging Mass Spectrometry for Plant Metabolomics  

E-print Network

#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 plant organs, including flowers, ovaries, aggregate fruits, fruits, leaves, tubers, bulbs, and seeds

Vertes, Akos

137

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

138

Microwave heating systems for atmospheric pressure: Nonequilibrium plasmas  

Microsoft Academic Search

Nonequilibrium plasma-chemical processing is attracting increasing interest because of the possibility of creating mixtures of active species that would not be available in thermal equilibrium. For significant throughput of reactants it would be advantageous to create nonequilibrium plasmas in large volumes of atmospheric-pressure mixtures of gases. Techniques for accomplishing this are very limited at present. Here we describe a novel

G. E. Guest; R. A. Dandl

1989-01-01

139

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

140

Atmospheric pressure and suicide attempts in Helsinki, Finland.  

PubMed

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?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. PMID:22278192

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

2012-11-01

141

Atmospheric Pressure Plasma Jet Treatment of Polyethylene Surfaces for  

E-print Network

Atmospheric Pressure Plasma Jet Treatment of Polyethylene Surfaces for Adhesion Improvement Uwe] The pretreatment modifies the surface properties of the substrate, thereby improving the adhesion strength parts of a substrate selectively.[3,4] Also, in contrast to most corona treatments (and dielectric

Greifswald, Ernst-Moritz-Arndt-Universität

142

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

143

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

144

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

145

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

146

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...

147

Carbonation of epoxy methyl soyate at atmospheric pressure  

Technology Transfer Automated Retrieval System (TEKTRAN)

Carbonated methyl soyates were prepared from epoxy methyl soyate by the introduction of carbon dioxide at the oxirane position. Carbonation was performed with carbon dioxide gas by sparging carbon dioxide through the epoxy esters at atmospheric pressure in the presence of tetrabutylammonium bromide...

148

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.

149

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

150

Radio jet refraction in galactic atmospheres with static pressure gradients  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

151

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

Microsoft Academic Search

Experiments have been performed to simulate the shallow ascent and surface release of water and brines under low atmospheric pressure. Atmospheric pressure was treated as an independent variable and water temperature and vapor pressure were examined as a function of total pressure variation down to low pressures. The physical and thermal responses of water to reducing pressure were monitored with

Alistair Simon Bargery; Alexander Barrett; Lionel Wilson; Jennie S. Gilbert

2010-01-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

154

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

155

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

156

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

157

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

158

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

159

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

160

Beam heat load and pressure rise in a cold vacuum chamber  

Microsoft Academic Search

The beam heat load and the pressure in the vacuum chamber of the cold bore superconducting undulator installed at ANKA (ANgstrom source KArlsruhe) have been monitored for almost two years. Possible sources of the observed heat load could be synchrotron radiation from upstream magnets, image currents, electron and ion bombardment. In this paper, the various possible contributions to the heat

S. Casalbuoni; A. Grau; M. Hagelstein; R. Rossmanith; F. Zimmermann; B. Kostka; E. Mashkina; E. Steffens; A. Bernhard; D. Wollmann; T. Baumbach

2007-01-01

161

A Water-Explicit Lattice Model of Heat-, Cold-, and Pressure-Induced Protein Unfolding  

E-print Network

treatment of hydrophobic hydration is sufficient to produce cold, pressure, and thermal denaturation. We consider here the simplest representation of a protein: a hydrophobic homopolymer. We show that an explicit-bonding interactions, as well as con- figurational entropy (4). Walter Kauzmann first suggested that the hydrophobic

162

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

PubMed Central

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

2014-01-01

163

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

164

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

165

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

166

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

167

Atmospheric pressure non-thermal plasma: Sources and applications  

NASA Astrophysics Data System (ADS)

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

Napartovich, A. P.

2008-07-01

168

Optimizing a remote sensing instrument to measure atmospheric surface pressure  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

169

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

NASA Astrophysics Data System (ADS)

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

Khosraviani, Kourosh; Leung, Albert M.

2009-04-01

170

Design and Test of a Liquid Oxygen / Liquid Methane Thruster with Cold Helium Pressurization Heat Exchanger  

NASA Technical Reports Server (NTRS)

A liquid oxygen / liquid methane 2,000 lbf thruster was designed and tested in conjuction with a nozzle heat exchanger for cold helium pressurization. Cold helium pressurization systems offer significant spacecraft vehicle dry mass savings since the pressurant tank size can be reduced as the pressurant density is increased. A heat exchanger can be incorporated into the main engine design to provide expansion of the pressurant supply to the propellant tanks. In order to study the systems integration of a cold-helium pressurization system, a 2,000 lbf thruster with a nozzle heat exchanger was designed for integration into the Project Morpheus vehicle at NASA Johnson Space Center. The testing goals were to demonstrate helium loading and initial conditioning to low temperatures, high-pressure/low temperature storage, expansion through the main engine heat exchanger, and propellant tank injection/pressurization. The helium pressurant tank was an existing 19 inch diameter composite-overwrap tank, and the targert conditions were 4500 psi and -250 F, providing a 2:1 density advantage compared to room tempatrue storage. The thruster design uses like-on-like doublets in the injector pattern largely based on Project Morpheus main engine hertiage data, and the combustion chamber was designed for an ablative chamber. The heat exchanger was installed at the ablative nozzle exit plane. Stand-alone engine testing was conducted at NASA Stennis Space Center, including copper heat-sink chambers and highly-instrumented spoolpieces in order to study engine performance, stability, and wall heat flux. A one-dimensional thermal model of the integrated system was completed. System integration into the Project Morpheus vehicle is complete, and systems demonstrations will follow.

Melcher, John C.; Morehead, Robert L.; Atwell, Matthew J.; Hurlbert, Eric A.

2015-01-01

171

Removal of paper microbial contamination by atmospheric pressure DBD discharge  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

172

Diagnostic methods used for atmospheric pressure thermal arc plasma  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

173

Cellular membrane collapse by atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

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

2014-01-01

174

Atmospheric-pressure plasma sources for biomedical applications  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

175

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

176

Intense and highly energetic atmospheric pressure plasma jet arrays  

NASA Astrophysics Data System (ADS)

This thesis documents the efforts taken to produce highly ionized and concentrated atmospheric pressure plasma using an arrayed atmospheric pressure plasma jet (APPJ) system. The honeycomb-shaped array features seven plasma jets operating in close enough proximity to one another to exhibit jet-to-jet coupling behavior. Optimal gas flow rates for the system were determined and intense plasma plumes composed of argon and/or helium are generated. Optical emission spectroscopy was employed to observe the charged particles responsible for the emissions of each gas discharge and APPJ operation mode. Plasma etching of indium tin oxide glass was conducted to verify the highly energetic properties of a plasma generated using two dissimilar gases, in order to confirm the possibility of plasma coupling between them.

Furmanski, John Ryan

177

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

178

Beta-type Stirling engine operating at atmospheric pressure  

Microsoft Academic Search

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

Serdar Yucesu; Tolga Topgul; Melih Okur

2005-01-01

179

Reaction mechanism of TEOS and O3 atmospheric pressure CVD  

Microsoft Academic Search

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

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

1991-01-01

180

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

181

Negative ion-atmospheric pressure photoionization-mass spectrometry  

Microsoft Academic Search

The ionization mechanism in the novel atmospheric pressure photoionization mass spectrometry (APPI-MS) in negative ion mode\\u000a was studied thoroughly by the analysis of seven compounds in 17 solvent systems. The compounds possessed either gas-phase\\u000a acidity or positive electron affinity, whereas the solvent systems had different polarities and gas-phase acidities and some\\u000a of them positive electron affinities. The analytes that possessed

Tiina J. Kauppila; Tapio Kotiaho; Risto Kostiainen; Andries P. Bruins

2004-01-01

182

Abatement of perfluorinated compounds using microwave plasmas at atmospheric pressure  

Microsoft Academic Search

Microwave plasmas sustained at atmospheric pressure, for instance by electromagnetic surface waves, can be efficiently used to abate greenhouse-effect gases such as perfluorinated compounds. As a working example, we study the destruction and removal efficiency (DRE) of SF6 at concentrations ranging from 0.1% to 2.4% of the total gas flow where N2, utilized as a purge gas, is the carrier

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

2003-01-01

183

Evolutionary pressures on planktonic production of atmospheric sulphur  

NASA Astrophysics Data System (ADS)

The possibility that dimethylsulphide (DMS) produced by marine phytoplankton is the major source of cloud condensation nuclei in the remote marine atmosphere is examined. Calculations of relative evolutionary pressure in models of individual and group selection are reviewed, showing that neither climate modulation nor altruism cloud have been the primary factors in the evolution of midocean DMS production. It is found that the midocean DMS production can be explained by selection based on local interactions such as osmoregulation.

Caldeira, Ken

1989-02-01

184

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

185

Mass analysis of an atmospheric pressure plasma needle discharge  

NASA Astrophysics Data System (ADS)

Mass spectrometric measurements of a plasma needle (an example of atmospheric pressure non-equilibrium plasma source) were made for neutrals and ions. The measurements were performed for the same geometry as the standard plasma needles albeit for a somewhat increased gas flow. We discuss some of the problems of performing mass analysis at atmospheric pressures. The yields of N, O and NO radicals from the plasma needle were determined for different powers of the RF source and different flow rates of working gas. Positive ions generated by the plasma needle itself were measured for the first time. Significant conversion of feed gases (nitrogen and oxygen) into radicals and ions of N and O, and NO was observed as well as depletion of atomic radicals N and O which in chemical reactions form more complex molecules. Biomedical and nanotechnology applications of atmospheric pressure plasmas require a detailed understanding of the source, and mass analysis is perhaps the best technique to focus on chemical kinetics and in many ways interaction with surfaces.

Malovi?, G.; Pua?, N.; Lazovi?, S.; Petrovi?, Z.

2010-06-01

186

Sterilization and decontamination of surfaces using atmospheric pressure plasma discharges  

SciTech Connect

The goal of the program is to demonstrate that an atmospheric pressure plasma discharge can rapidly and effectively sterilize or decontaminate surfaces that are contaminated with model biological and chemical warfare agents. The plasma is produced by corona discharge from an array of pins and a ground plane. The array is constructed so that various gases, like argon or helium, can be flowed past the pins where the discharge is initiated. The pin array can be biased using either DC. AC or pulsed discharges. the work done to date has focused on the sterilization of aluminum, polished steel and tantalum foil metal coupons, about 2 cm on a side and 2 mm thick, which have been inoculated with up to 10{sup 6} spores per coupon of Bacillus subtilis var niger or Bascillus stearothermorphilus. Results indicate that 5 minute exposures to the atmospheric pressure plasma discharge can reduce the viable spore count by 4 orders of magnitude. The atmospheric pressure discharge is also effective in decomposing organic phosphate compounds that are stimulants for chemical warfare agents. Details of the decomposition chemistry, by-product formation, and electrical energy consumption of the system will be discussed.

Garate, E.; Gornostaeva, O.; Alexeff, I.; Kang, W.L.

1999-07-01

187

Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry  

SciTech Connect

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

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

2006-05-15

188

Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology  

NASA Technical Reports Server (NTRS)

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

Button, Amy B.; Sweterlitsch, Jeffrey J.

2013-01-01

189

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; Sweterlitsch, Jeffrey

2011-01-01

190

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

191

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

192

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

193

Arctic warming, atmospheric blocking and cold European winters in CMIP5 models  

NASA Astrophysics Data System (ADS)

Amplified Arctic warming is expected to have a significant long-term influence on the midlatitude atmospheric circulation by the latter half of the 21st century. Potential influences of recent and near future Arctic changes on shorter timescales are much less clear, despite having received much recent attention in the literature. In this letter, climate models from the recent CMIP5 experiment are analysed for evidence of an influence of Arctic temperatures on midlatitude blocking and cold European winters in particular. The focus is on the variability of these features in detrended data and, in contrast to other studies, limited evidence of an influence is found. The occurrence of cold European winters is found to be largely independent of the temperature variability in the key Barents-Kara Sea region. Positive correlations of the Barents-Kara temperatures with Eurasian blocking are found in some models, but significant correlations are limited.

Woollings, T.; Harvey, B.; Masato, G.

2014-01-01

194

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

195

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

SciTech Connect

A high-pressure fuel system for LNG vehicles with direct-injection natural gas engines has been developed and demonstrated on a heavy-duty truck. A new concept for utilizing the ''cold energy'' associated with LNG vehicles to generate mechanical power to drive auxiliary equipment (such as high-pressure fuel pumps) has also been developed and demonstrated in the laboratory. The high-pressure LNG fuel system development included the design and testing of a new type of cryogenic pump utilizes multiple chambers and other features to condense moderate quantities of sucked vapor and discharge supercritical LNG at 3,000 to 4,000 psi. The pump was demonstrated on a Class 8 truck with a Westport high-pressure direct-injection Cummins ISX engine. A concept that utilizes LNG's ''cold energy'' to drive a high-pressure fuel pump without engine attachments or power consumption was developed. Ethylene is boiled and superheated by the engine coolant, and it is cooled and condensed by rejecting h eat to the LNG. Power is extracted in a full-admission blowdown process, and part of this power is applied to pump the ethylene liquid to the boiler pressure. Tests demonstrated a net power output of 1.1. hp at 1.9 Lbm/min of LNG flow, which is adequate to isentropically pump the LNG to approximately 3,400 psi..

powers,Charles A.; Derbidge, T. Craig

2001-03-27

196

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

197

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

PubMed Central

Candida albicans is one of the main species able to form a biofilm on almost any surface, causing both skin and superficial mucosal infections. The worldwide increase in antifungal resistance has led to a decrease in the efficacy of standard therapies, prolonging treatment time and increasing health care costs. Therefore, the aim of this work was to demonstrate the applicability of atmospheric plasma at room temperature for inactivating C. albicans growing in biofilms without thermally damaging heat-sensitive materials. This so-called cold atmospheric plasma is produced by applying high voltage to accelerate electrons, which ionize the surrounding air, leading to the production of charged particles, reactive species, and photons. A newly developed plasma device was used, which exhibits a large plasma-generating surface area of 9 by 13 cm (117 cm2). Different time points were selected to achieve an optimum inactivation efficacy range of ?3 log10 to 5 log10 reduction in CFU per milliliter, and the results were compared with those of 70% ethanol. The results obtained show that contact-free antifungal inactivation of Candida biofilms by cold atmospheric plasma is a promising tool for disinfection of surfaces (and items) in both health care settings and the food industry, where ethanol disinfection should be avoided. PMID:22467505

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

2012-01-01

198

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.

199

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.

200

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

201

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.

202

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

203

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

204

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

205

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

206

Stable microwave coaxial cavity plasma system at atmospheric pressure  

SciTech Connect

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

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

2008-05-15

207

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

208

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

209

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

210

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

211

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

212

Low-pressure CVD of LaB6 for cold cathode devices  

NASA Astrophysics Data System (ADS)

A study of the low-pressure chemical vapor deposition of lanthanum hexaboride, a low work function material, is reported. The activation energy was measured to be 42.7 kJ/mol; the deposits are fine-grained and polycrystalline, with an average grain size of 5-10 microns. This structure is suitable for cold cathode devices. Details of the deposition and characterization of LaB6 are discussed.

Jang, Qin; Laferla, Raffaele; Kaplan, Richard B.; Ahern, Brian S.; Weyburne, David W.

213

Development of an Atmospheric Pressure Ionization Mass Spectrometer  

NASA Technical Reports Server (NTRS)

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

1998-01-01

214

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

215

Pluto's Insolation History: Latitudinal Variations and Effects on Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

Since previous insolation modeling in the early 1990’s, 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. Depending on the timescales of volatile migration, some consequences of these insolation patterns may be manifested in the surface features revealed by New Horizons. For any single rotation of Pluto there is a latitude that receives more insolation relative to the others. Often this is the sub-subsolar latitude but it can also be an arctic circle latitude when near-polar regions of Pluto experience the "midnight sun". We define the amount of that greatest insolation value over the course of one rotation as the "maximum diurnal insolation" (MDI). We find that MDI is driven to its highest values 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, appears to correlate with Pluto's currently occurring midnight sun as quantified by the MDI parameter. If insolation (as parameterized by the MDI value) is the single dominant factor driving Pluto's atmospheric pressure, this “Midnight Sun Model” predicts that Pluto's maximum atmospheric pressure will be reached in 2017 followed by a steady decline. Pluto's maximum diurnal insolation value begins dropping after 2017 due to two factors: Pluto’s sub-solar point becomes more equatorial (lessening the midnight sun effect) and the planet continues to recede toward aphelion. This work was supported in part by the NASA New Horizons mission to Pluto under SwRI Subcontract 299433Q.

Earle, Alissa M.; Binzel, Richard P.

2014-11-01

216

Electron kinetics in a microdischarge in nitrogen at atmospheric pressure  

SciTech Connect

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

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

2013-12-14

217

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

218

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

219

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

220

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

221

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

222

Plasmas Generated With Gas Mixtures at the Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

Several applications, such as metal surface nitriding, medical instrument sterilization and chemical analysis, have been developed or improved using a gas mixture as plasmogen gas. Research carried out on these subjects covers the aspect of knowing the processes that take place in plasmas which depend on the densities of the different plasma particles and their energy values. In this paper, the results obtained from the application of spectroscopic techniques for the characterization of surface wave discharges at the atmospheric pressure, generated with more than one gas type, are presented, particularly for the Ar-He, Ar-Ne and Ar-N2 plasmas.

Calzada, M. D.; Muñoz, J.; Rincón, R.; Jiménez, M.; Sáez, M.

223

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

224

Twin injection-needle plasmas at atmospheric pressure  

SciTech Connect

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

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

2007-04-02

225

Next generation of the atmospheric pressure loading service  

NASA Astrophysics Data System (ADS)

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

Petrov, Leonid; Boy, Jean-Paul

2013-04-01

226

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

227

On the mechanisms of sensible heat transfer between snow and a cold atmosphere  

NASA Astrophysics Data System (ADS)

The mechanisms of heat exchange between the atmosphere and the snowpack during cold, stable periods are imperfectly understood. Air flow over smooth snow surfaces under weak synoptic forcing creates weak or intermittently turbulent mixing conditions, strong thermal stratification, interaction of non-turbulent motions, and the possible decoupling of the boundary layer from the surface. These conditions pose serious challenges for modeling snow thermodynamics (including melt) and snow-atmosphere interactions. Numerous modellers have discovered that realistic energy balance simulations are extremely sensitive to the nature of the stability corrections used, and in many cases have found it necessary to include a windless exchange coefficient in order to maintain some sensible heat transfer to the snowpack during periods of low mechanical mixing. Snow energetics under cold atmospheric conditions in mid-winter were investigated by making direct measurement of all the snow mass and energy balance components at a homogeneous, flat, and open snow field near Saskatoon, Saskatchewan, Canada. The energy balance was dominated by the net radiation flux, which was usually negative due to longwave radiation losses during clear sky conditions. Owing to the aerodynamically smooth surface and often stable conditions, the measured turbulent heat fluxes were very small (much smaller than the net radiation flux). Surface temperatures declined dramatically under strongly negative net radiation conditions and were poorly coupled to the atmospheric temperature, however the near-surface internal temperatures of the snowpack were not observed to cool significantly, but rather they tracked near to the air temperature. In order to maintain the observed thermal conditions of the snowpack, the true sensible heat flux to the snowpack would have to be much larger than that which was measured by eddy correlation technique and could be expected to closely mirror the net longwave radiation. The observed coupling between the atmosphere and the snowpack interior clearly indicates a sensible heat transfer mechanism which is responsive to the radiation forcing, but can operate under very weakly turbulent conditions. This mechanism is neither described by current turbulent transfer formulations nor measureable with eddy correlation systems. A new hypothesis of sensible heat exchange between the atmosphere and a permeable snowpack is presented, in which the conditions of the interfacial layer of the porous snowpack are theoretically considered. In combination, penetration of air flow into the snowpack, an inherently large surface area for heat exchange, and thermal non-equilibrium conditions all play a dynamic role in allowing the radiation balance to control the sensible heat flux. Well-developed turbulent conditions are not required to support this exchange. Approaches to calculating these processes are compared to observations of snowpack thermodynamics and atmospheric boundary layer fluxes and states.

Helgason, W.; Pomeroy, J. W.

2009-12-01

228

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

229

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

230

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

231

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

232

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

PubMed

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

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

2013-07-01

233

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

234

A Water-Explicit Lattice Model of Heat-, Cold-, and Pressure-Induced Protein Unfolding  

PubMed Central

We investigate the effect of temperature and pressure on polypeptide conformational stability using a two-dimensional square lattice model in which water is represented explicitly. The model captures many aspects of water thermodynamics, including the existence of density anomalies, and we consider here the simplest representation of a protein: a hydrophobic homopolymer. We show that an explicit treatment of hydrophobic hydration is sufficient to produce cold, pressure, and thermal denaturation. We investigate the effects of the enthalpic and entropic components of the water-protein interactions on the overall folding phase diagram, and show that even a schematic model such as the one we consider yields reasonable values for the temperature and pressure ranges within which highly compact homopolymer configurations are thermodynamically stable. PMID:17766342

Patel, Bryan A.; Debenedetti, Pablo G.; Stillinger, Frank H.; Rossky, Peter J.

2007-01-01

235

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

PubMed Central

We studied the cold unfolding of myoglobin with Fourier transform infrared spectroscopy and compared it with pressure and heat unfolding. Because protein aggregation is a phenomenon with medical as well as biotechnological implications, we were interested in both the structural changes as well as the aggregation behavior of the respective unfolded states. The cold- and pressure-induced unfolding both yield a partially unfolded state characterized by a persistent amount of secondary structure, in which a stable core of G and H helices is preserved. In this respect the cold- and pressure-unfolded states show a resemblance with an early folding intermediate of myoglobin. In contrast, the heat unfolding results in the formation of the infrared bands typical of intermolecular antiparallel beta-sheet aggregation. This implies a transformation of alpha-helix into intermolecular beta-sheet. H/2H-exchange data suggest that the helices are first unfolded and then form intermolecular beta-sheets. The pressure and cold unfolded states do not give rise to the intermolecular aggregation bands that are typical for the infrared spectra of many heat-unfolded proteins. This suggests that the pathways of the cold and pressure unfolding are substantially different from that of the heat unfolding. After return to ambient conditions the cold- or pressure-treated proteins adopt a partially refolded conformation. This aggregates at a lower temperature (32 degrees C) than the native state (74 degrees C). PMID:11964250

Meersman, Filip; Smeller, László; Heremans, Karel

2002-01-01

236

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.

237

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

238

Characterization of HOCl using atmospheric pressure ionization mass spectrometry  

SciTech Connect

HOCl is an important intermediate in stratospheric and tropospheric chemistry. Although it can be readily measured in laboratory systems at low pressures ({le}20 Torr) using conventional electron impact ionization mass spectrometry, there is a need for a measurement technique that can operate at higher pressures, up to 1 atm in air. One such technique seeing increasing use is atmospheric pressure ionization mass spectrometry (API-MS). The authors report here studies of the API-MS of {approximately}0.5--50 ppm HOCl at a total pressure of 1 atm and room temperature. Major peaks from the ion-adducts with Cl{sup {minus}} and OCI{sup {minus}} were observed. The Br{sup {minus}} adduct of HOCl can also be generated using bromoform in the discharge region of the ion source. At the lower range of HOCl concentrations studied in air, the O{sub 2}{sup {minus}} adduct and small parent peaks assigned to HOCl{sup {minus}} were observed. The species present as minor impurities in the HOCl source (Cl{sub 2}, Cl{sub 2}O and HCl) can be readily distinguished through identification of the parent ion for Cl{sub 2}, or as their adducts with Cl{sup {minus}} and Br{sup {minus}} for Cl{sub 2}O and HCI. The identification of HOCl was confirmed using electron impact ionization time-of-flight mass spectrometry (El-MS). HOCl was quantified using EI-MS to measure the Cl{sub 2} generated when the HOCl reacted heterogeneously on a water-ice/HCl surface and independently by photolysis of the HOCl to generate atomic chlorine, which was trapped using propene and measured as chloroacetone. The implications for the use of API-MS for measuring HOCl in laboratory systems and in ambient air are discussed.

Caldwell, T.E.; Foster, K.L.; Benter, T.; Langer, S.; Hemminger, J.C.; Finlayson-Pitts, B.J.

1999-10-14

239

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

PubMed Central

The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples. PMID:22822404

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

2012-01-01

240

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

241

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.

242

Controlled Microdroplet Transport in an Atmospheric Pressure Microplasma  

E-print Network

We report the controlled injection of near-isolated micron-sized liquid droplets into a low temperature He-Ne steady-state rf plasma at atmospheric pressure. The H2O droplet stream is constrained within a 2 mm diameter quartz tube. Imaging at the tube exit indicates a log-normal droplet size distribution with an initial count mean diameter of 15 micrometers falling to 13 micrometers with plasma exposure. The radial velocity profile is approximately parabolic indicating near laminar flow conditions with the majority of droplets travelling at >75% of the local gas speed and having a plasma transit time of microreactors and remote delivery of active species for pla...

Maguire, P D; Kelsey, C P; Bingham, A; Montgomery, E P; Bennet, E D; Potts, H E; Rutherford, D; McDowell, D A; Diver, D A; Mariotti, D

2015-01-01

243

Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma  

NASA Astrophysics Data System (ADS)

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

Setareh, Salarieh; Davoud, Dorranian

2013-11-01

244

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

245

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

246

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. PMID:25685843

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

2015-01-01

247

Generation of reactive species by an atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

The role of gas mixing in reactive species delivery to treatment surfaces for an atmospheric pressure capacitively coupled plasma helium jet is investigated by numerical modelling. Atomic oxygen in the jet effluent is shown to quickly convert to ozone for increasing device to surface separation due to the molecular oxygen present in the gas mixture. Surface profiles of reactive oxygen species show narrow peaks for atomic oxygen and broader surface distributions for ozone and metastable species. Production efficiency of atomic oxygen to the helium plasma jet by molecular oxygen admixture is shown to be dependent on electro-negativity. Excessive molecular oxygen admixture results in negative ion dominance over electrons which eventually quenches the plasma. Interaction of the plasma jet with an aqueous surface showed hydrogen peroxide as the dominant species at this interface. Gas heating by the plasma is found to be dominated by elastic electron collisions and positive ion heating. Comparison with experimental measurements for atomic oxygen shows good agreement.

Kelly, S.; Turner, M. M.

2014-12-01

248

Atmospheric pressure plasma surface modification of carbon fibres  

NASA Astrophysics Data System (ADS)

Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He/O2 and Ar plasma treatments, mainly attributed to an increase in the density of the C-O single bond at the carbon fibre surfaces. The O/C ratio increased to 0.182 after 1-s He plasma treatment, and remained approximately constant after longer treatment. After exposure in an ambient air at room temperature for a month the O/C ratio at the plasma treated surfaces decreased to 0.151, which is close to that of the untreated ones. It can be attributed to the adsorption of hydrocarbon contamination at the plasma treated surfaces.

Kusano, Y.; Andersen, T. L.; Michelsen, P. K.

2008-03-01

249

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

250

Efficacy of nonthermal atmospheric pressure plasma for tooth bleaching.  

PubMed

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 energy source, which has no deleterious effects on the tooth surface. PMID:25685843

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

2015-01-01

251

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

252

Plasmid DNA damage induced by helium atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

A helium atmospheric pressure plasma jet (APPJ) is applied to induce damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level induced in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.

Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia

2014-03-01

253

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

254

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

255

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

256

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

257

The hairline plasma: An intermittent negative dc-corona discharge at atmospheric pressure for plasma medical applications  

SciTech Connect

A cold atmospheric pressure plasma source, called hairline plasma, for biological and medical applications has been developed. Using the physical effect of the negative dc corona discharge, a nanosecond pulsed microplasma has been created. The device produces a very thin (dapprox30 mum) plasma filament with a length of up to 1.5 cm. Due to this geometrical parameters this plasma is particularly suitable for the treatment of microscopic cavities. The low plasma temperature allows to treat the human skin without any heating or painful irritation.

Bussiahn, R.; Brandenburg, R.; Gerling, T.; Kindel, E.; Lange, H.; Lembke, N.; Weltmann, K.-D.; Woedtke, Th. von [Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Kocher, T. [Unit of Periodontology, Dental School, Ernst-Moritz-Arndt-University Greifswald, Rotgerberstr. 8, 17489 Greifswald (Germany)

2010-04-05

258

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.

259

Static Water Contact Angle Analysis of Cyclonic Atmospheric Pressure Plasma-Activated Polycarbonate  

NASA Astrophysics Data System (ADS)

Polycarbonate (PC) films were activated using cyclonic atmospheric pressure plasma. The experimentally measured gas phase temperature was from 30 to 95 °C, demonstrating that this cyclonic atmospheric pressure plasma can treat heat-sensitive polymeric materials at the low temperatures. The surface hydrophilicity changes of cyclonic atmospheric pressure plasma-treated PC films were determined by water contact angle analysis. The activation effects of plasma operational parameters including treatment time, plasma power, and distance of nozzle to substrate on the PC surface features were investigated. The glow feature and luminous plasma species in the cyclonic atmospheric pressure plasma were identified by optical emission spectroscopy (OES). Cyclonic atmospheric pressure plasma-activated PC films showed a significant decrease in water contact angle. In this investigation, we developed an innovative technique for chamberless polymeric surface activation by this atmospheric pressure plasma processing.

Huang, Chun; Wu, Shin-Yi; Liu, Yu-Chia; Chang, Ya-Chi; Tsai, Ching-Yuan

2011-01-01

260

Surface atmospheric pressure excitation of the translational mode of the inner , J.-P. Boy  

E-print Network

for Environmental Prediction) Climate Forecast System Reanalysis (CFSR) models, we show that atmospheric pressure a challenging instrumental task for the near future. Keywords: Slichter mode; ECMWF atmospheric model; NCEP/CFSR

Paris-Sud XI, Université de

261

The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.  

PubMed

A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M?+?77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI. PMID:25248413

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

2014-11-01

262

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

PubMed

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

Peikert, D; Smolander, J

1991-01-01

263

Surface Modification by Atmospheric Pressure Plasma for Improved Bonding  

NASA Astrophysics Data System (ADS)

An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from <5° to 40° over a period of 12 hours. When stored under a nitrogen purge, the water contact angle of a clean surface increased from <5° to 30° over a period of 40-60 hours. The change in contact angle resulted from the adsorption of nonanal onto the exposed surface hydroxyl groups. The rate of adsorption of nonanal under a nitrogen purged atmosphere ranged from 0.378+/-0.011 hr-1 to 0.182+/-0.008 hr -1 molecules/(cm2•s), decreasing as the fraction of hydrogen-bonded hydroxyl groups increased from 49% to 96% on the SiO 2 surface. The adsorption of the organic contaminant could be suppressed indefinitely by storing the silicon wafers in the presence of activated carbon or in a freezer at -22°C. The enhancement of adhesive bond strength and durability for carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024 was demonstrated with the atmospheric pressure helium-oxygen plasma. All surfaces studied were converted from a hydrophobic state with a water contact angle of 65° to 80° into a hydrophilic state with a water contact angle between 20° and 40° within 5 seconds of plasma exposure. X-ray photoelectron spectroscopy confirmed that the carbon atoms on the carbon-fiber/epoxy composite were oxidized, yielding 17 atom% carboxylic acid groups, 10% ketones or aldehydes and 9% alcohols. Analysis of stainless steel and aluminum by XPS illustrate oxidation of the metal surface and an increase in the concentration of hydroxyl groups in the oxide film. Following plasma activation, the total hydroxyl species concentration on stainless steel increased from 31% to 57%, while aluminum exhibited an increase from 4% to 16% hydroxyl species. Plasma activation of the surface led to an increase in bond strength of the different surfaces by up to 150% when using Cytec FM300 and FM300-2 epoxy adhesives. Wedge crack extension tests following plasma activation revealed cohesive failure percentages of 97% for carbon-fiber/epoxy composite bonded to stainless steel, and 96% for aluminum bonded to itself. The bond strength and durability of the substrates correlated with changes in the specific surface chemistry, not the wetting angle or the morphological properties of the material. This suggests that enhanced chemical bonding at the interface was responsible for the improvement in mechanical properties following plasma activation. The surface preparation of polymers and composites using atmospheric pressure plasmas is a promising technique for replacing traditional methods of surface preparation by sanding, grit blasting or peel ply. After oxygen plasma activation and joining the materials together with epoxy, one observes 100% cohesive failure within the c

Williams, Thomas Scott

264

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

NASA Astrophysics Data System (ADS)

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

Isbary, Georg

265

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

266

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

267

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

PubMed Central

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

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

2010-01-01

268

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

269

Effect of Heat, Cold, and Pressure on the Transverse Carpal Ligament and Median Nerve: A Pilot Study  

PubMed Central

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/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

270

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

271

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

272

How a dusty cold pool can change the diurnal evolution of the Saharan Atmospheric Boundary Layer  

NASA Astrophysics Data System (ADS)

The Saharan Atmospheric Boundary Layer (SABL) structure, dynamics, thermodynamics and composition over the Central Sahara, associated with several concomittant dust lifting processes observed/modelled on 21 June 2011, in the framework of the FENNEC 2011 Special Observing period, are analysed. The aerosol optical depth on that day was in excess of 3. On the morning of June 21, dust lifting occurred at the passing of the African Easterly Waves over Mauritania with dust being raised by cold-pools issued from convective systems having developped the previous day. Behind this wave, the harmattan flow was channeled between the Hoggar and the Atlas and also generated dust. The dust production was amplified when this flow experienced further constriction between dusty density currents flowing down the Atlas slopes and an intense monsoon pulse from the west of the Hoggar also generating much dust. Two aircraft (the SAFIRE Falcon and the FAAM BAe 146)operated over Mauritania and Mali on that day enabled to document the complex interactions between the monsoon flow, the intertropical front, the density currents from the Atlas, in the SABL. AROME operational simulations werealso used to analyse how the different air masses have interacted to form the observed complex multi-layer dust structure in the SABL. Afternoon Falcon 20 and BAe 146 flights sampled the growth of the SABL. A clear influence of the cold pool and the dusty layers above can be observed on the developpement of the boundary layer. Finally, two AROME simulations (one with and one without prognostic dust) were used to investigate the influence of the complex dust layers on the dynamics/thermodynamics of the developping convective boundary layer over the Central Sahara.

Kocha, C.; Flamant, C.; Marnas, F.; Chaboureau, J. P.; Parker, D.; Marsham, J.; Knippertz, P.; Garcia-Carreras, L.

2012-04-01

273

Miniature differential mobility spectrometry using atmospheric pressure photoionization.  

PubMed

Positive and negative ion spectra have been obtained with a miniature differential mobility spectrometer equipped with a photoionization source operating at atmospheric pressure. With benzene as a dopant, providing C6H6+ as reactant ion, protonated molecular ions and proton-bound dimer ions were obtained with dimethyl methylphosphonate and butanone. The spectra obtained from gas chromatographic injections of aromatic hydrocarbons, benzene, toluene, and the xylenes, produced the molecular ions when the moisture level was very low, but at a high level the hydrated proton was also present. Possible mechanisms for the formation of protonated products are discussed. Negative ions were produced from electron capture by sulfur hexafluoride using benzene or acetone as dopant. Photoionization of nitrogen dioxide led to the formation of the nitrate ion whose yield was a nonlinear function of concentration. The use of a suitable dopant enhanced ion formation by up to 2 orders of magnitude, and limits of detection in both the positive and negative modes were all at the sub ppm(v) level. The study makes a strong case for the use of a photoionization source as an alternative to the radioactive 63Ni source. PMID:16808465

Nazarov, Erkinjon G; Miller, Raanan A; Eiceman, Gary A; Stone, John A

2006-07-01

274

Pulsed, atmospheric pressure plasma source for emission spectrometry  

DOEpatents

A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

Duan, Yixiang; Jin, Zhe; Su, Yongxuan

2004-05-11

275

Formation of plasma dust structures at atmospheric pressure  

SciTech Connect

The formation of strongly coupled stable dust structures in the plasma produced by an electron beam at atmospheric pressure was detected experimentally. Analytical expressions were derived for the ionization rate of a gas by an electron beam in an axially symmetric geometry by comparing experimental data with Monte Carlo calculations. Self-consistent one-dimensional simulations of the beam plasma were performed in the diffusion drift approximation of charged plasma particle transport with electron diffusion to determine the dust particle levitation conditions. Since almost all of the applied voltage drops on the cathode layer in the Thomson glow regime of a non-self-sustained gas discharge, a distribution of the electric field that grows toward the cathode is produced in it; this field together with the gravity produces a potential well in which the dust particles levitate to form a stable disk-shaped structure. The nonideality parameters of the dust component in the formation region of a highly ordered quasi-crystalline structure calculated using computational data for the dust particle charging problem were found to be higher than the critical value after exceeding which an ensemble of particles with a Yukawa interaction should pass to the crystalline state.

Filippov, A. V., E-mail: fav@triniti.ru; Babichev, V. N.; Dyatko, N. A.; Pal', A. F.; Starostin, A. N.; Taran, M. D. [Troitsk Institute for Innovation and Fusion Research, State Research Center of Russian Federation (Russian Federation); Fortov, V. E. [Russian Academy of Sciences, Institute for High Energy Densities (Russian Federation)

2006-02-15

276

Infrared polarization spectroscopy of CO 2 at atmospheric pressure  

NASA Astrophysics Data System (ADS)

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

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

2004-04-01

277

Atmospheric pressure nonthermal plasmas for bacterial biofilm prevention and eradication.  

PubMed

Biofilms are three-dimensional structures formed by surface-attached microorganisms and their extracellular products. Biofilms formed by pathogenic microorganisms play an important role in human diseases. Higher resistance to antimicrobial agents and changes in microbial physiology make treating biofilm infections very complex. Atmospheric pressure nonthermal plasmas (NTPs) are a novel and powerful tool for antimicrobial treatment. The microbicidal activity of NTPs has an unspecific character due to the synergetic actions of bioactive components of the plasma torch, including charged particles, reactive species, and UV radiation. This review focuses on specific traits of biofilms, their role in human diseases, and those effects of NTP that are helpful for treating biofilm infections. The authors discuss NTP-based strategies for biofilm control, such as surface modifications to prevent bacterial adhesion, killing bacteria in biofilms, and biofilm destruction with NTPs. The unspecific character of microbicidal activity, proven polymer modification and destruction abilities, low toxicity for human tissues and absence of long-living toxic compounds make NTPs a very promising tool for biofilm prevention and control. PMID:25869456

Ermolaeva, Svetlana A; Sysolyatina, Elena V; Gintsburg, Alexander L

2015-01-01

278

Atmospheric pressure molecular imaging by infrared MALDI mass spectrometry.  

PubMed

An atmospheric pressure (AP) MALDI imaging interface was developed for an orthogonal acceleration time-of-flight mass spectrometer and utilized to analyze peptides, carbohydrates, and other small biomolecules using infrared laser excitation. In molecular imaging experiments, the spatial distribution of mock peptide patterns was recovered with a detection limit of approximately 1 fmol/pixel from a variety of MALDI matrixes. With the use of oversampling for the image acquisition, a spatial resolution of 40 microm, 5 times smaller than the laser spot size, was achieved. This approach, however, required that the analyte was largely removed at the point of analysis before the next point was interrogated. Native water in plant tissue was demonstrated to be an efficient natural matrix for AP infrared laser desorption ionization. In soft fruit tissues from bananas, grapes, and strawberries, potassiated ions of the most abundant metabolites, small carbohydrates, and their clusters produced the strongest peaks in the spectra. Molecular imaging of a strawberry skin sample revealed the distribution of the sucrose, glucose/fructose, and citric acid species around the embedded seeds. Infrared AP MALDI mass spectrometric imaging without the addition of an artificial matrix enables the in vivo investigation of small biomolecules and biological processes (e.g., metabolomics) in their natural environment. PMID:17222016

Li, Yue; Shrestha, Bindesh; Vertes, Akos

2007-01-15

279

Power modulation in an atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

Power modulation in an atmospheric pressure capacitively coupled radio frequency plasma jet is investigated by numerical modelling. The dynamics of successively pulsing the applied power on and off for a helium-oxygen (˜0.6%) plasma is investigated. The impact of power pulsing on reactive species generation and gas heating is discussed with control opportunities emphasized. Power modulation shows linear control for reactive species and heat flux delivery to a treatment surface above an initial phase of power growth. Power is found to be coupled primarily to the electrons with electron loss rates determining the interference between successive power modulation phases. Plasma decay in the power off phase is characterized by a large initial electron loss in the first 0.5 µs followed by ambipolar decay dominated by ions of opposite charge. Power modulation effects on gas heating show a larger range of temperature control when compared with convection cooling. Reactive oxygen species reaching a treatment surface are shown to typically vary over an order of magnitude for variation in the duty cycle.

Kelly, S.; Turner, M. M.

2014-12-01

280

Atmospheric pressure plasma treatment of lipopolysaccharide in a controlled environment  

NASA Astrophysics Data System (ADS)

The atmospheric pressure plasma jet (APPJ) has been widely investigated for sterilization of surfaces, but studies on surface chemical changes of model compounds in controlled environments have been lacking. We present measurements on lipopolysaccharide (LPS) using x-ray photoelectron spectroscopy after 1% O2 in Ar APPJ treatments in controlled ambients composed of N2/Ar mixtures. By varying the N2 concentration from 20% to 100%, we find that the interaction of the jet with the environment plays a major role in modifying surface reactions. This is due to the plasma exciting N2, which quenches reactive oxygen species (ROS) that would otherwise modify the film surface. By minimizing the interaction of the APPJ with the environment, e.g. by changing the APPJ geometry, we show that surface modifications increase even when the plasma itself is removed farther from the LPS surface. Measurements on the biological activity, optical emission, and ozone production of the jet using O2, N2 and O2/N2 admixtures all demonstrate that ROS are readily quenched by N2 species excited by the plasma. These results clearly reveal the importance of considering plasma-environment interactions for APPJ treatments of surfaces.

Bartis, E. A. J.; Graves, D. B.; Seog, J.; Oehrlein, G. S.

2013-08-01

281

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 A. (2010). Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure. JoVE. 43

Vertes, Akos

282

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

E-print Network

. A relatively simple zero-dimensional model that treats only the Paschen breakdown mechanism in the dischargeDynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges of pulse phenomena in conventional parallel-plate dielectric-barrier controlled atmospheric-pressure glow

Raja, Laxminarayan L.

283

Threshold wind velocity for particle entrainment at sub-atmospheric pressures as on the planet Mars  

Microsoft Academic Search

Low pressure wind tunnel data on particle entrainment were compared with predictions of two entrainment models in an attempt to improve the predictive capability for conditions near the Martian surface, where atmospheric pressure is 100-200 times lower than on earth. Fletcher's (1976) correlation model concerned the erosion of granular materials by atmospheric flows. Phillip's (1980) force balance model defined a

M. Phillips

1984-01-01

284

PPPL-3281, Preprint: January 1998, UC-426 Synthesis of Ozone at Atmospheric Pressure  

E-print Network

1 PPPL-3281, Preprint: January 1998, UC-426 Synthesis of Ozone at Atmospheric Pressure-coupled plasma (ICP) torch to synthesize ozone at atmospheric pressure is explored. Ozone concentrations up and ~11 kVA with an argon/oxygen mixture as the plasma-forming gas. A gaseous oxygen quench formed ozone

285

Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films  

Microsoft Academic Search

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

Minghui Yin; Lingli Zhao; Xiangyu Xu; Shouguo Wang

2008-01-01

286

Interplay of discharge and gas flow in atmospheric pressure plasma jets Nan Jiang,1  

E-print Network

Interplay of discharge and gas flow in atmospheric pressure plasma jets Nan Jiang,1 JingLong Yang,2 2011) Interplay of discharge and gas flow in the atmospheric pressure plasma jets generated with three an optical schlieren system. Gas flow gains a forward momentum from discharge except for the case of overflow

Zexian, Cao

287

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

288

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

289

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. In this contribution, we explore the feasibility of laser ablation atmospheric pressure photoionization (LAAPPI-time-of-flight (TOF)-MSI without any sample preparation. Leaf mass spectra were also recorded with laser ablation

Vertes, Akos

290

A Novel APPI-MS Setup for In Situ Degradation Product Studies of Atmospherically Relevant Compounds: Capillary Atmospheric Pressure Photo Ionization (cAPPI)  

Microsoft Academic Search

We report on the development of a novel atmospheric pressure photoionization setup and its applicability for in situ degradation\\u000a product studies of atmospherically relevant compounds. A custom miniature spark discharge lamp was embedded into an ion transfer\\u000a capillary, which separates the atmospheric pressure from the low pressure region in the first differential pumping stage of\\u000a a conventional atmospheric pressure ionization

Hendrik Kersten; Valerie Derpmann; Ian Barnes; Klaus J. Brockmann; Rob O’Brien; Thorsten Benter

291

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

PubMed

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

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

2005-07-01

292

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

293

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

294

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

295

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

296

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

PubMed

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

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

2012-08-01

297

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

298

Cold atmospheric plasma in combination with mechanical treatment improves osteoblast growth on biofilm covered titanium discs.  

PubMed

Treatment of implants with peri-implantitis is often unsuccessful, because an instrumented implant surface and residual microbial biofilm impedes re-osseointegration. The application of cold atmospheric plasma (CAP) could be a simple and effective strategy to overcome the inherent problems of peri-implantitis treatment. CAP is able to destroy and eliminate bacterial biofilms. Additionally, it increases the wettability of titanium, which supports cellular attachment. In this study, the behaviour of osteoblasts on titanium discs was analysed after treatment of bacterial biofilms with CAP, brushing, or a combination of both. A human plaque biofilm was cultured on titanium discs. Treatment with a brush (BR), 1% oxygen/argon CAP (PL), or brushing combined with CAP (BR + PL) was used to eliminate the biofilm. Discs without biofilm (C), autoclaved biofilm (AUTO) and untreated biofilm (BIO) served as controls. Subsequently, human osteoblastic cell growth (MG-63) was observed after 1 and 24 h. Biofilm remnants on BR and PL impaired osteoblastic cell development, whereas the BR + PL provided an increased area of osteoblastic cells. A five-day cell growth was only detectable on BR + PL treated discs. The combination of established brushing and CAP application may be a promising strategy to treat peri-implantitis. PMID:25818439

Duske, Kathrin; Jablonowski, Lukasz; Koban, Ina; Matthes, Rutger; Holtfreter, Birte; Sckell, Axel; Nebe, J Barbara; von Woedtke, Thomas; Weltmann, Klaus Dieter; Kocher, Thomas

2015-06-01

299

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

300

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

PubMed Central

Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log10 CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D23°C values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma. PMID:22582068

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

2012-01-01

301

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

302

Tailoring non-equilibrium atmospheric pressure plasmas for healthcare technologies  

NASA Astrophysics Data System (ADS)

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

Gans, Timo

2012-10-01

303

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.

304

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

305

Investigating effects of atmospheric-pressure plasma on the process of wound healing.  

PubMed

Cold atmospheric-pressure plasma jets (APPJ) have excellent applications in biomedicine. Advantages of APPJ include lack of need for vacuum systems, capability of operation for a long time, and safe to be directly touched by living tissues such as a human body. In this study, an APPJ was generated by a dielectric barrier and applied for the treatment of chemical wounds. This APPJ worked with argon and was driven by high-voltage pulses. This paper compares the spontaneous healing of wounds and a stimulated healing using daily APPJ treatment. Biological data, such as hematological, biochemical, and histological parameters, were remarked. The mortality and morbidity of the untreated samples were reported after 20 days in comparison with the plasma-treated samples, which were alive after these days. Experimental results demonstrated that an increase in the oxidative stress could result in the decreased destruction of lesions by controlling the infection growth. These results were related to the presence of reactive oxygen species and reactive nitrogen species in the plasma volume, which were detected by optical emission spectroscopy. PMID:25758659

Salehi, Shahram; Shokri, Asana; Khani, Mohammad Reza; Bigdeli, Mohammadreza; Shokri, Babak

2015-01-01

306

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

Microsoft Academic Search

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

Caley A. Robertson

2011-01-01

307

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

308

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

309

Plasma Ion Sources for Atmospheric Pressure Ionization Mass Spectrometry.  

NASA Astrophysics Data System (ADS)

Atmospheric pressure ionization (API) sources using direct-current (DC) and radio-frequency (RF) plasma have been developed in this thesis work. These ion sources can provide stable discharge currents of ~ 1 mA, 2-3 orders of magnitude larger than that of the corona discharge, a widely used API source. The plasmas can be generated and maintained in 1 atm of various buffer gases by applying -500 to -1000 V (DC plasma) or 1-15 W with a frequency of 165 kHz (RF plasma) on the needle electrode. These ion sources have been used with liquid injection to detect various organic compounds of pharmaceutical, biotechnological and environmental interest. Key features of these ion sources include soft ionization with the protonated molecule as the largest peak, and superb sensitivity with detection limits in the low picogram or femtomole range and a linear dynamic range over ~4 orders of magnitude. The RF plasma has advantages over the DC plasma in its ability to operate in various buffer gases and to produce a more stable plasma. Factors influencing the performance of the ion sources have been studied, including RF power level, liquid flow rate, chamber temperature, solvent composition, and voltage affecting the collision induced dissociation (CID). Ionization of hydrocarbons by the RF plasma API source was also studied. Soft ionization is generally produced. To obtain high sensitivity, the ion source must be very dry and the needle-to-orifice distance must be small. Nitric oxide was used to enhance the sensitivity. The RF plasma source was then used for the analysis of hydrocarbons in auto emissions. Comparisons between the corona discharge and the RF plasma have been made in terms of discharge current, ion residence time, and the ion source model. The RF plasma source provides larger linear dynamic range and higher sensitivity than the corona discharge, due to its much larger discharge current. The RF plasma was also observed to provide longer ion residence times and was not limited by space-charge effect as in the corona source.

Zhao, Jian-Guo

1994-01-01

310

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

311

Effect of Atmospheric Pressure on Wet Bulb Depression  

NASA Astrophysics Data System (ADS)

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

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

312

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.

Hopwood, Jeffrey

2011-05-31

313

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

Microsoft Academic Search

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

Xavier Comas; Lee Slater; A. S. Reeve

2011-01-01

314

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

315

Influence of processing gases on the properties of cold atmospheric plasma SiOxCy coatings  

NASA Astrophysics Data System (ADS)

Thin layers of SiOxCy (y = 4-x and 3 ? x ? 4) were applied using a cold atmospheric plasma torch on glass substrates. The aim was to investigate using Atomic Force Microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (Tof-Sims) the influence of the gases used on the morphology and composition of the deposits. A hexamethyldisilane (HMDS) precursor was injected in post-discharge in an air or nitrogen plasma using a carrier gas (air or nitrogen) and was applied on the substrate previously pre-treated by an air or nitrogen plasma. The carrier gas and plasma gas flows and the distance between the substrate and the plasma torch, the scanning speed, and the precursor flows were kept constant during the study. The gas used during activation pre-treatment showed no particular influence on the characteristics of the deposit. When air is used both as plasma and carrier gas, the coating layer is thicker (96 nm) than when nitrogen is used (64 nm). It was also evidenced that the gas carrying the precursor has little influence on the hydrophobicity of the coating, contrary to the plasma gas. The latter significantly influences the surface characteristics of the coatings. When air is used as plasma gas, a compact coating layer is obtained and the surface has a water contact angle (WCA) of 82°. When nitrogen is used, the deposit is more hydrophobic (WCA of 100°) and the deposit morphology is different. This increase in hydrophobicity could be correlated to the increase of Sisbnd Osbnd C bonds in the upper surface layers evidenced by XPS analyzes. This observation was then confirmed by Tof-Sims analyzes carried out on these thin layers. A uniform distribution of Carbons in the siloxane coating could also be observed using Tof-Sims 2D reconstruction images of cross sections of the deposited layers.

Hamze, H.; Jimenez, M.; Deresmes, D.; Beaurain, A.; Nuns, N.; Traisnel, M.

2014-10-01

316

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

317

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

318

Effect of Atmospheric Pressure on Wet Bulb Depression  

Microsoft Academic Search

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

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

2008-01-01

319

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

320

Wavelet filter analysis of local atmospheric pressure effects on gravity variations  

NASA Astrophysics Data System (ADS)

An efficient method is proposed for the analysis of atmospheric pressure effects on gravity variations. It processes gravity and pressure signals using an orthogonal filter bank derived from high-degree Daubechies wavelets. The method introduces the atmospheric pressure admittance, which is both time- and frequency-dependent, and thus provides more information about when and how the frequency components in the pressure signal influence gravity variations. We demonstrate the efficiency of the wavelet method by applying it to observations from the Wuhan (China) superconducting gravimeter station. The analysis of gravity and pressure signals in 14 sub-bands with different bandwidths covering a frequency range from 0.176 to 720 cpd (cycles per day) reveals that local atmospheric pressure fluctuations start to induce obvious effects on gravity variations in the seismic band 0.52 1.04 mHz (periods 16 to 32 min) and highly correlate with gravity variation in the long-period seismic mode band 0.26 0.52 mHz (periods 32 64 min). The harmonics of solar-heating-induced atmospheric tides play a leading role in interfering with the variation of gravity residuals in the frequency band 0.704 11.25 cpd (periods 128 min to 1.42 day). Local atmospheric pressure effects on gravity variation are very strong in the frequency band 0.176 0.704 cpd (periods 1.42 5.69 day). Accurately filtering quarter-diurnal tides into a narrow band further demonstrates the efficiency of the wavelet method. After removing secular gravity changes and long-period atmospheric pressure variations, we show that there are obvious variations of local pressure admittance on time scales of hours to days. We also reveal seasonal variability of pressure admittances in the band 0.176 0.352 cpd (periods 2.84 5.69 day) after removing the effects of solar-heating atmospheric tides.

Hu, X.-G.; Liu, L.-T.; Hinderer, J.; Sun, H.-P.

2005-11-01

321

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.

322

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

323

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

324

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.

325

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

326

PHYSICAL REVIEW E 88, 013107 (2013) Spectroscopic study of plasma evolution in runaway nanosecond atmospheric-pressure  

E-print Network

atmospheric-pressure He discharges S. Yatom,1 E. Stambulchik,2 V. Vekselman,1 and Ya. E. Krasik1 1 Department studies of repetitive 170 ns duration pulsed discharge have been carried out in atmospheric-pressure N2 of electron density in He and N2 gases at the pressure of 105 Pa [14]. Also, a pulsed-dc excited atmospheric

327

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

328

Volume Effects of Atmospheric-Pressure Plasma in Liquids  

Microsoft Academic Search

Generation of chemical species by atmospheric-pres- sure plasma treatment of aqueous liquids is a result of reactions at the plasma\\/gas-liquid interface and subsequent diffusion and convection processes into the liquid volume. Using color forming reactions, acidification as well as generation of nitrite is visualized in the water treated by a surface dielectric barrier discharge under atmospheric conditions in ambient air.

Katrin Oehmigen; Tomáš Hoder; Christian Wilke; Ronny Brandenburg; Marcel Hahnel; Klaus-Dieter Weltmann; Thomas von Woedtke

2011-01-01

329

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

330

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

331

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

SciTech Connect

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

Ksandopulo, G.I.

1995-08-25

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

Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications  

NASA Astrophysics Data System (ADS)

Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron-level aerosol chemical and biological threats. Polymer solution concentration, electrospinning voltage, and deposition areal density were varied to establish the relationship of processing-structure-filtration efficiency for electrospun fiber mats. A high barrier efficiency of greater than 99.5% was achieved on electrospun fiber mats without sacrificing air permeability and pressure drop. ii) Fabrication and Characterization of Multifunctional ZnO/Nylon 6 nanofibers ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process, The electrospinning of polymer solution and electrospraying of ZnO particles were carried out simultaneously such that the ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers. The prepared ZnO/Nylon 6 nanofiber mats were tested for detoxifying characteristics against simulants of C-B agents. The results showed that ZnO/Nylon 6 functional nanofiber mats exhibited good detoxification action against paraoxon and have antibacterial efficiency over 99.99% against both the gram-negative E. coli and gram positive B. cereus bacteria. iii) Improving adhesion of electrospun nanofiber mat onto woven fabric by plasma pretreatment of substrate fabric and plasma-electrospinning hybrid process Electrospun nanofibers were deposited onto plasma-pretreated woven fabric to improve the adhesion. In addition, the plasma-electrospinning hybrid process was developed and used in which the nanofibers were subjected to in-situ plasma treatment during electrospinning. The effects of plasma treatement on substrate fabric and electrospun fibers were characterized by water contact angle test, XPS analyses. The improvement of nanofiber adhesive properties on fabric substrate was evaluated by peel test, flex resistance test and abrasion resistance test. The test results showed that the plasma treatment caused introduction of active chemical groups on substrate fabric and electrospun nanofibers. These active chemical assisted in possible cross-linking formation between nanofiber mat and substrate fabric, and this hypothesi

Vitchuli Gangadharan, Narendiran

2011-12-01

335

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

336

Optical emission study of a directcurrent, atmospheric-pressure nonthermal plasma microjet  

Microsoft Academic Search

Summary form only given. Over the past few years, various atmospheric-pressure plasma jets were developed, most of which operate at radio frequency or pulsed DC power with inert gases such as He as the working gas of choice. This work aims to study a direct current driven, atmospheric-pressure non-thermal plasma microjet (PMJ) operated in air and in water with a

WeiDong Zhu; J. Lopez; K. H. Becker

2010-01-01

337

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

SciTech Connect

Nitrogen molecule dissociation in a pulse-periodic atmospheric-pressure dielectric barrier discharge is numerically analyzed. It is shown that the quenching rate of predissociation states at atmospheric pressure is relatively low and the production of nitrogen atoms in this case can be adequately described using the cross section for electron-impact dissociation of N{sub 2} molecules taken from the paper by P.C. Cosby [J. Chem. Phys. 98, 9544 (1993)].

Popov, N. A., E-mail: npopov@mics.msu.su [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2013-05-15

338

Plasma-polymerized tetrafluoroethylene coatings on silica particles by atmospheric-pressure glow discharge  

Microsoft Academic Search

This paper presents a method of novel plasma treatment for fine particles by the atmospheric-pressure glow (APG) discharge, in which particles were circulated and repeatedly plasma-treated at atmospheric pressure. Using this method, plasma-polymerized tetrafluoroethylene (TFE) film formations on the porous granulated silica particles of 152 ?m mean diameter were investigated. The XPS C(1s) spectrum of the treated surfaces deconvoluted into

Yasushi Sawada; Masuhiro Kogama

1997-01-01

339

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

340

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

341

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

Microsoft Academic Search

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

Andrei V. Nastuta; Ionut Topala; Gheorghe Popa

2011-01-01

342

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

343

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 dynamics model was developed for the ablation of water-rich targets by infrared laser pulses at atmospheric explosion on laser ablation dynamics, and it is relevant for the preparative, analytical, and medical

Vertes, Akos

344

Water cycles in closed ecological systems: effects of atmospheric pressure  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

345

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

346

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

347

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

348

Vertical thermal structure of the Venus atmosphere from temperature and pressure measurements  

NASA Technical Reports Server (NTRS)

Accurate temperature and pressure measurements were made on the Vega-2 lander during its entire descent. The temperature and pressure at the surface were 733 K and 89.3 bar, respectively. A strong temperature inversion was found in the upper troposphere. Several layers with differing static stability were visible in the atmospheric structure.

Linkin, V. M.; Blamon, Z.; Lipatov, A. P.; Devyatkin, S. I.; Dyachkov, A. V.; Ignatova, S. I.; Kerzhanovich, V. V.; Malyk, K.; Stadny, V. I.; Sanotskiy, Y. V.

1986-01-01

349

Ignition during hydrogen release from high pressure into the atmosphere  

NASA Astrophysics Data System (ADS)

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

Oleszczak, P.; Wolanski, P.

2010-12-01

350

Atmospheric pressure and temperature profiling using near IR differential absorption lidar  

NASA Technical Reports Server (NTRS)

The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.

Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Weng, C. Y.

1983-01-01

351

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

352

Atmospheric pressure effects on ²²²Rn transport across the earth-air interface  

Microsoft Academic Search

The effect of large-scale atmospheric pressure changes on the 22Rn tlux across the soil-air interface is investigated. Field data collected during 1972 and 1973 show that pressure changes of 1-2'7o associated with the passage of frontal systems produce changes in the 222Rn flux from 20 to 60%, depending upon the rate of change of pressure and its duration. A simple

William E. Clements; Marvin H. Wilkening

1974-01-01

353

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

354

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

355

A Model for Atmospheric Pressure Fluctuations in the Mesoscale Range  

Microsoft Academic Search

It is shown, given perturbations of the jet stream wind system similar to those reported from balloon and aircraft studies, that it is possible to calculate ground level pressure fluctuations. Using a density stratified model of the troposphere and a constant gravity field, and assuming the jet stream to act as a traveling disturbance, a simple linear model predicts the

I. Tolstoy; T. J. Herron

1969-01-01

356

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

357

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

358

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

NASA Astrophysics Data System (ADS)

A combination of state-of-the-art theoretical methods has been used to obtain an atomic-level picture of classical and quantum ordering of protons in cold high-pressure solid hydrogen. We focus mostly on phases II and III of hydrogen, exploring the effects of quantum nuclear motion on certain features of these phases (through a number of ab initio path integral molecular dynamics (PIMD) simulations at particular points on the phase diagram). We also examine the importance of van der Waals forces in this system by performing calculations using the optB88-vdW density functional, which accounts for non-local correlations. Our calculations reveal that the transition between phases I and II is strongly quantum in nature, resulting from a competition between anisotropic inter-molecular interactions that restrict molecular rotation and thermal plus quantum fluctuations of the nuclear positions that facilitate it. The transition from phase II to III is more classical because quantum nuclear motion plays only a secondary role and the transition is determined primarily by the underlying potential energy surface. A structure of P21/c symmetry with 24 atoms in the primitive unit cell is found to be stable when anharmonic quantum nuclear vibrational motion is included at finite temperatures using the PIMD method. This structure gives a good account of the infra-red and Raman vibron frequencies of phase II. We find additional support for a C2/c structure as a strong candidate for phase III, since it remains transparent up to 300 GPa, even when quantum nuclear effects are included. Finally, we find that accounting for van der Waals forces improves the agreement between experiment and theory for the parts of the phase diagram considered, when compared to previous work which employed the widely-used Perdew-Burke-Ernzerhof exchange-correlation functional.

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

2013-02-01

359

Factors Associated With Blood Pressure Response to the Cold Pressor Test: The GenSalt Study  

PubMed Central

BACKGROUND Blood pressure (BP) response to the cold pressor test (CPT) has been associated with increased risk of cardiovascular disease. We studied risk factors associated with BP response to CPT. METHODS We conducted the CPT among 2,682 individuals in rural north China. BP was measured using a standard mercury sphygmomanometer prior to and at 0, 1, 2, and 4 minutes after the participants immersed their right hand in ice water for 1 minute. RESULTS Sex, age, and baseline BP levels were significantly associated with BP response to the CPT. For example, maximum systolic BP response (mean ± SD) was greater in women than in men (15.5±10.7 vs. 13.8±10.0mm Hg; P < 0.0001), correspondingly higher with age (12.4±8.7, 13.8±10.0, and 16.4±11.2mm Hg for those aged < 35, 35–44, and ? 45 years, respectively; P for trend < 0.0001), and greater with higher BP (13.5±10.0, 14.9±10.2, and 17.4±11.5mm Hg for those with baseline BP < 120/80, 120–139/80–89, and ? 140/90mm Hg, respectively; P for trend < 0.0001). In multivariable analyses, we also observed that higher body mass index, physical inactivity, and alcohol consumption were significantly associated with greater BP response to the CPT. CONCLUSIONS Our study indicates that females, older age, and elevated baseline BP levels are associated with greater BP response to the CPT. In addition, physical inactivity, higher weight, and alcohol consumption may also be related to BP hyperreactivity to stress. PMID:23727840

2013-01-01

360

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

SciTech Connect

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; Reichel, Jakob [Laboratoire Kastler Brossel, ENS, UPMC, CNRS, 24 rue Lhomond, 75005 Paris (France); Rosenbusch, Peter [LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 av de l’Observatoire, 75014 Paris (France)

2014-08-15

361

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

E-print Network

We describe and characterize a device for alkali vapor pressure modulation on the 100ms 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.

Vincent Dugrain; Peter Rosenbusch; Jakob Reichel

2014-07-31

362

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

363

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

PubMed Central

The ability of terrestrial microorganisms to grow in the near-surface environment of Mars is of importance to the search for life and protection of that planet from forward contamination by human and robotic exploration. Because most water on present-day Mars is frozen in the regolith, permafrosts are considered to be terrestrial analogs of the martian subsurface environment. Six bacterial isolates were obtained from a permafrost borehole in northeastern Siberia capable of growth under conditions of low temperature (0 °C), low pressure (7 mbar), and a CO2-enriched anoxic atmosphere. By 16S ribosomal DNA analysis, all six permafrost isolates were identified as species of the genus Carnobacterium, most closely related to C. inhibens (five isolates) and C. viridans (one isolate). Quantitative growth assays demonstrated that the six permafrost isolates, as well as nine type species of Carnobacterium (C. alterfunditum, C. divergens, C. funditum, C. gallinarum, C. inhibens, C. maltaromaticum, C. mobile, C. pleistocenium, and C. viridans) were all capable of growth under cold, low-pressure, anoxic conditions, thus extending the low-pressure extreme at which life can function. PMID:23267097

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

2013-01-01

364

Pressure sensing of the atmosphere by solar occultation using broadband CO2 absorption  

NASA Technical Reports Server (NTRS)

A technique for obtaining pressure at the tangent point in an IR solar occulation experiment is described. By measuring IR absorption in bands of atmospheric CO2 (e.g., 2.0, 2.7, or 4.3 microns), mean pressure values for each tangent point layer (vertical thickness 2 km or less) of the atmosphere can be obtained with rms errors of less than 3%. The simultaneous retrieval of pressure and gas concentration in a remote-sensing experiment will increase the accuracy of inverted gas concentrations and minimize the dependence of the experiment on pressure or mass path error resulting from use of climatological pressure data, satellite ephemeris, and instrument pointing accuracy.

Park, J. H.; Russell, J. M., III; Drayson, S. R.

1979-01-01

365

Fuel injection method and device providing simple atmospheric pressure compensation for engine incorporating open to atmosphere fuel pressure regulator valve  

Microsoft Academic Search

A device for fuel injection in an internal combustion engine which has an intake system is described, comprising: (a) fuel injector means, fitted to the intake system for injecting fuel into the intake system according to an opening and closing of the fuel injector means; (b) means for supplying pressurized fuel to the fuel injector means; (c) means for controlling

N. Kushi; H. Okano; N. Kobayashi; N. Sugita

1987-01-01

366

Effects of nonthermal atmospheric cold plasma on blueberry native microbiota and sensory attributes  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nonthermal processing interventions are important steps in decontaminating and/or preserving fresh fruits, such as blueberries. Cold plasma (CP) is a novel nonthermal technology potentially useful in food processing settings. The objectives of this work were to determine CP reduction of blueberry ba...

367

Nonthermal inactivation of the norovirus surrogate tulane virus on blueberries using atmospheric cold plasma  

Technology Transfer Automated Retrieval System (TEKTRAN)

Viruses are currently the leading cause of foodborne outbreaks, most of which are associated with foods consumed raw. Cold plasma (CP) is an emerging novel nonthermal technology that can be used for the surface decontamination of foods. This study investigated CP technology for the nonthermal inacti...

368

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

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

369

An analysis of the errors associated with the determination of atmospheric temperature from atmospheric pressure and density data  

NASA Technical Reports Server (NTRS)

A graph was developed for relating delta T/T, the relative uncertainty in atmospheric temperature T, to delta p/p, the relative uncertainty in the atmospheric pressure p, for situations, when T is derived from the slope of the pressure-height profile. A similar graph relates delta T/T to delta roh/rho, the relative uncertainty in the atmospheric density rho, for those cases when T is derived from the downward integration of the density-height profile. A comparison of these two graphs shows that for equal uncertainties in the respective basic parameters, p or rho, smaller uncertainties in the derived temperatures are associated with density-height rather than with pressure-height data. The value of delta T/T is seen to depend not only upon delta p or delta rho, and to a small extent upon the value of T or the related scale height H, but also upon the inverse of delta h, the height increment between successive observations of p or rho. In the case of pressure-height data, delta T/T is dominated by 1/delta h for all values of delta h; for density-height data, delta T/T is dominated by delta rho/rho for delta h smaller than about 5 km. In the case of T derived from density-height data, this inverse relationship between delta T/T and delta h applies only for large values of delta h, that is, for delta h 35 km. No limit exists in the fineness of usable height resolution of T which may be derived from densities, while a fine height resolution in pressure-height data leads to temperature with unacceptably large uncertainties.

Minzner, R. A.

1976-01-01

370

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

371

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

NASA Astrophysics Data System (ADS)

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

2014-04-01

372

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

373

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

374

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

375

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

376

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

PubMed

In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. PMID:24259213

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

2013-11-01

377

Acidification of reverse micellar nanodroplets by atmospheric pressure CO2.  

PubMed

Water absorption of atmospheric carbon dioxide lowers the solution pH due to carbonic acid formation. Bulk water acidification by CO(2) is well documented, but significantly less is known about its effect on water in confined spaces. Considering its prominence as a greenhouse gas, the importance of aerosols in acid rain, and CO(2)-buffering in cellular systems, surprisingly little information exists about the absorption of CO(2) by nanosized water droplets. The fundamental interactions of CO(2) with water, particularly in nanosized structures, may influence a wide range of processes in our technological society. Here results from experiments investigating the uptake of gaseous CO(2) by water pools in reverse micelles are presented. Despite the small number of water molecules in each droplet, changes in vanadium probes within the water pools, measured using vanadium-51 NMR spectroscopy, indicate a significant drop in pH after CO(2) introduction. Collectively, the pH-dependent vanadium probes show CO(2) dissolves in the nanowater droplets, causing the reverse micelle acidity to increase. PMID:21506532

Levinger, Nancy E; Rubenstrunk, Lauren C; Baruah, Bharat; Crans, Debbie C

2011-05-11

378

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

379

Spectroscopic and Electrical Analysis of Capacitively Coupled VHF plasma at Atmospheric Pressure for Plasma CVM process  

Microsoft Academic Search

Plasma CVM (Chemical Vaporization Machining) process using atmospheric VHF plasma is developed and have been studied in recent years. It is required to optimize the characterization of such plasma. In this poster, we report the experimental results of spectroscopic and electrical analysis of VHF dischrges in mixed gas (He\\/CF_4\\/O_2) used in CVM process. The total gas pressure is one atmosphere,

Shoichi Kawashima; Yasushi Oshikane; Kenichi Takemoto; Kazuya Yamamura; Katsuyoshi Endo; Yuzo Mori

2001-01-01

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

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

382

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

383

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

384

Production of Fullerenes by Low Temperature Plasma Chemical Vaper Deposition under Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

A gas phase reactor developed for generating homogenous low temperature plasma under atmospheric pressure was found to provide a new method for producing fullerenes by a plasma chemical vapor deposition (CVD) process. Into an afterglow region of atmospheric pressure Ar He mixed gas plasma, an aromatic hydrocarbon was introduced and decomposed into black soot under appropriate reaction conditions. A benzene solution of the soot showed two clear HPLC peaks with retention times corresponding well to those of C60 and C70. The formation of C60 was further confirmed by UV spectroscopy.

Inomata, Kiyoto; Aoki, Nobuyuki; Koinuma, Hideomi

1994-02-01

385

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

386

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

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

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

E-print Network

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...

Rosat, Séverine; Rogister, Yves

2014-01-01

389

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

390

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

391

Pool boiling heat transfer enhancement over cylindrical tubes with water at atmospheric pressure, Part I: Experimental results  

E-print Network

Pool boiling heat transfer enhancement over cylindrical tubes with water at atmospheric pressure online 4 May 2013 Keywords: Pool boiling Heat transfer enhancement Open microchannels Cylindrical tube boiling heat transfer over enhanced cylindrical microchannel test surfaces with water at atmospheric

Kandlikar, Satish

392

Retrieval of upper atmosphere pressure-temperature profiles from high resolution solar occultation spectra  

NASA Technical Reports Server (NTRS)

Pressure-temperature profiles over the 18 to 75 km altitude range were retrieved from 0.01 cm(-1) resolution infrared solar absorption spectra recorded with the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer operating in the solar occultation mode during the Spacelab 3 shuttle mission (April 30 to May 1, 1985). The analysis method is described and preliminary results deduced for five occultation events are compared to correlative pressure-temperature measurments.

Rinsland, C. P.; Russell, J. M., III; Park, J. H.; Namkung, J.

1987-01-01

393

Life modeling of atmospheric and low pressure plasma-sprayed thermal-barrier coating  

NASA Technical Reports Server (NTRS)

The cycles-to-failure vs cycle duration data for three different thermal barrier coating systems, which consist of atmospheric pressure plasma-sprayed ZrO2-8 percent Y2O3 over similarly deposited or low pressure plasma sprayed Ni-base alloys, are presently analyzed by means of the Miller (1980) oxidation-based life model. Specimens were tested at 1100 C for heating cycle lengths of 1, 6, and 20 h, yielding results supporting the model's value.

Miller, R. A.; Argarwal, P.; Duderstadt, E. C.

1984-01-01

394

Hydrolase-catalyzed reactions in membrane reactors at atmospheric and high pressure  

Microsoft Academic Search

Membrane reactors could serve as a tool for enzyme-catalyzed reactions and they enable the performance of catalytic reaction, enzyme recovery and product isolation as a one-step process. In the presented work, the use of continuous flat-shape and continuous tubular membrane enzymatic reactors for different enzymatic systems at atmospheric pressure and at supercritical conditions are described. In a high-pressure continuous enzymatic

Mateja Primoži?; Muzafera Paljevac; Željko Knez

2009-01-01

395

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

NASA Astrophysics Data System (ADS)

Moorings 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, Åükrü

2014-06-01

396

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

397

Simulation of Rarefied Gas Flows in Atmospheric Pressure Interfaces for Mass Spectrometry Systems  

NASA Astrophysics Data System (ADS)

The understanding of the gas dynamics of the atmospheric pressure interface is very important for the development of mass spectrometry systems with high sensitivity. While the gas flows at high pressure (>1 Torr) and low pressure (<10-3 Torr) stages are relatively well understood and could be modeled using continuum and molecular flows, respectively, the theoretical modeling or numeric simulation of gas flow through the transition pressure stage (1 to 10-3 Torr) remains challenging. In this study, we used the direct simulation Monte Carlo (DMSC) method to develop the gas dynamic simulations for the continuous and discontinuous atmospheric pressure interfaces (API), with different focuses on the ion transfer by gas flows through a skimmer or directly from the atmospheric pressure to a vacuum stage, respectively. The impacts by the skimmer location in the continuous API and the temporal evolvement of the gas flow with a discontinuous API were characterized, which provide a solid base for the instrument design and performance improvement.

Garimella, Sandilya; Zhou, Xiaoyu; Ouyang, Zheng

2013-12-01

398

Simulation of rarefied gas flows in atmospheric pressure interfaces for mass spectrometry systems.  

PubMed

The understanding of the gas dynamics of the atmospheric pressure interface is very important for the development of mass spectrometry systems with high sensitivity. While the gas flows at high pressure (>1 Torr) and low pressure (<10(-3) Torr) stages are relatively well understood and could be modeled using continuum and molecular flows, respectively, the theoretical modeling or numeric simulation of gas flow through the transition pressure stage (1 to 10(-3) Torr) remains challenging. In this study, we used the direct simulation Monte Carlo (DMSC) method to develop the gas dynamic simulations for the continuous and discontinuous atmospheric pressure interfaces (API), with different focuses on the ion transfer by gas flows through a skimmer or directly from the atmospheric pressure to a vacuum stage, respectively. The impacts by the skimmer location in the continuous API and the temporal evolvement of the gas flow with a discontinuous API were characterized, which provide a solid base for the instrument design and performance improvement. PMID:24043523

Garimella, Sandilya; Zhou, Xiaoyu; Ouyang, Zheng

2013-12-01

399

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

400

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

PubMed

We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 ?m dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bar and for O2 volume mixing ratios above 50% of Earth's present-day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 ?m and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We also performed detectability studies for JWST transit transmission spectroscopy and found that the 1.06 and 1.27??m dimer features could be detectable (SNR>3) for an Earth analogue orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis. We calculated the required signal-to-noise ratios to detect and characterize O2 monomer and dimer features in direct imaging-reflected spectra and found that signal-to-noise ratios greater than 10 at a spectral resolving power of R=100 would be required. PMID:24432758

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

2014-02-01

401

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

402

Using Dimers to Measure Biosignatures and Atmospheric Pressure for Terrestrial Exoplanets  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

403

Entrainment of cold gas into thermal plasma jets  

Microsoft Academic Search

There is increasing evidence that the entrainment of cold gas surrounding a turbulent plasma jet is more of an engulfment type process rather than simple diffusion. A variety of diagnostic techniques have been employed to determine the development of turbulence in a plasma jet and to measure concentration and temperatures of the cold gas entrained into atmospheric-pressure argon plasma jets

E. Pfender; J. Fincke; R. Spores

1991-01-01

404

Sweeping electrostatic probes in atmospheric pressure arc plasmas-Part II: temperature determination  

Microsoft Academic Search

In a previous paper, it was shown that only the ion portion of the probe characteristics curve (V-I) can be used to estimate the temperature from probes sweeping in the column of a flowing atmospheric pressure arc plasma. Methods relating the measured ion current directly to the temperature can be used, if a particle density-temperature relationship is available. However, several

C. Fanara

2005-01-01

405

Mechanism of Blood Coagulation by Nonthermal Atmospheric Pressure Dielectric Barrier Discharge Plasma  

Microsoft Academic Search

Mechanisms of blood coagulation by direct contact of nonthermal atmospheric pressure dielectric barrier discharge (DBD) plasma are investigated. This paper shows that no significant changes occur in the pH or Ca2+ concentration of blood during discharge treatment. Thermal effects and electric field effects are also shown to be negligible. Investigating the hypothesis that the discharge treatment acts directly on blood

Sameer U. Kalghatgi; Gregory Fridman; Moogega Cooper; Gayathri Nagaraj; Marie Peddinghaus; Manjula Balasubramanian; Victor N. Vasilets; Alexander F. Gutsol; Alexander Fridman; Gary Friedman

2007-01-01

406

Excitation of atmospheric pressure uniform dielectric barrier discharge using repetitive unipolar nanosecond-pulse generator  

Microsoft Academic Search

Dielectric barrier discharge (DBD) excitation by unipolar high voltage pulses is a promising approach for producing non-thermal plasma at atmospheric pressure. In this study, a magnetic compression solid-state pulsed power generator was used to produce repetitive nanosecond pulses for the excitation. The DBD is created using two liquid electrodes. The electrical characteristics of the discharge voltage and current are illustrated

Tao Shao; Yang Yu; Cheng Zhang; Dongdong Zhang; Zheng Niu; Jue Wang; Ping Yan; Yuanxiang Zhou

2010-01-01

407

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

408

Application of Langmuir Probe Method to the Atmospheric Pressure Discharge Plasma  

Microsoft Academic Search

The heat balance model in the probe tip applied to atmospheric pressure plasma is constructed. Considering the natural convective heat loss, the limitation of plasma density for probe application to such a plasma is estimated. The rough limit is about ne = 1018 m-3. Four kind of materials (Cu, SUS, W, Al) are used for probe tips, and are tested

Hiroto Matsuura; Yasuhiro Matsumura; Ken Nakano

2008-01-01

409

A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas  

Microsoft Academic Search

It is well known that the use of Langmuir probes in `high' pressure plasmas (atmospheric and above) is extremely difficult due to the high degree of collisionality. In addition, electric arcs used in industry are highly non-homogeneous. In particular the degree of ionization varies from zero at the arc edges to values close to full ionization near the axis. Existing

C. Fanara; I. M. Richardson

2001-01-01

410

Influence of atmospheric vapour pressure deficit on ozone responses of snap bean (Phaseolus vulgaris L.) genotypes  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two genotypes of snapbean (Phaseolus vulgaris L.), one known to be sensitive to ozone and the other resistant, were examined to determine their response to atmospheric vapor pressure deficit (VPD) in the presence and absence of ozone. Plants were grown in Outdoor Plant Environment Chambers in combin...

411

Sulphur group analysis in solid matrices by atmospheric pressure-temperature programmed reduction  

Microsoft Academic Search

The atmospheric pressure-temperature programmed reduction (AP-TPR) has become an established and reliable method amongst the different sulphur characterisation techniques for solid materials, like coal and coal derived products, rubber and clay. The analytical method is based upon the fact that specific sulphur functional groups are hydrogenated at specific temperatures. During the last few years, several adjustments have been made to

Jan Yperman; Inge I. Maes; Heidi Van den Rul; Steven Mullens; Joke Van Aelst; Dirk V. Franco; Jules Mullens; Lucien C. Van Poucke

1999-01-01

412

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

Microsoft Academic Search

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

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

1999-01-01

413

Air Purification Effect of Positively and Negatively Charged Ions Generated by Discharge Plasma at Atmospheric Pressure  

Microsoft Academic Search

In this paper, the air purification effect of positively and negatively charged ions generated by discharge plasma at atmospheric pressure is reported. We have developed a novel ion generation device which consists of a cylindrical glass tube and attached inner and outer mesh electrodes. With the application of AC voltage between the electrodes, positively charged ions and negatively charged ions

Kazuo Nishikawa; Hideo Nojima

2001-01-01

414

Numerical modelling of atmospheric pressure gas discharges leading to plasma production  

Microsoft Academic Search

In this paper, we give a detailed review of recent work carried out on the numerical characterization of non-thermal gas discharge plasmas in air at atmospheric pressure. First, we briefly describe the theory of discharge development for dielectric barrier discharges, which is central to the production of non-equilibrium plasma, and we present a hydrodynamic model to approximate the evolution of

G E Georghiou; A P Papadakis; R Morrow; A C Metaxas

2005-01-01

415

Do temperature and atmospheric pressure affect the incidence of serious odontogenic infection?  

Microsoft Academic Search

Objective. The purpose of this study was to investigate the popular belief that the incidence of odontogenic cellulitis is weather-related. Two meteorologic parameters were examined: temperature and atmospheric pressure.Study Design. To test the hypothesis being studied, a retrospective cohort study design was used. Medical reports of all patients with serious odontogenic cellulitis who were treated at the Salpêtrière University Hospital

Jean-Paul Meningaud; Françoise Roudot-Thoraval; Jacques-Charles Bertrand; Francis Guilbert

1998-01-01

416

Radio frequency induced ionized collisional flow model for application at atmospheric pressures  

E-print Network

Radio frequency induced ionized collisional flow model for application at atmospheric pressures and radio frequency (rf) induced plasma-sheath dynamics, using multifluid equations. For the former, argon inherent in nonequilibrium discharges such as obtained through radio frequency (rf) or microwave excitation

Roy, Subrata

417

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

418

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

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

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

421

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

422

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

423

Role of dissociative recombination in the excitation kinetics of an argon microwave plasma at atmospheric pressure  

Microsoft Academic Search

A collisional radiative model was developed in order to investigate the influence of dissociative recombination on the Saha–Boltzmann plasma equilibrium. As the dissociative recombination products are not well known, their relative importance was tested through comparison with the distribution of line intensities obtained in a microwave argon discharge produced at atmospheric pressure by a surface wave. It was found that

A. Sa´inz; J. Margot; M. C. Garci´a; M. D. Calzada

2005-01-01

424

Measurement of Metastable Atom Populations Along an Argon Plasma Column Generated at Atmospheric Pressure  

Microsoft Academic Search

This paper describes a procedure for experimental determination of metastable and resonant populations along a surface wave argon plasma column at atmospheric pressure. As modeling work progresses extensively, an experimental database is necessary to confirm these models. Obtained results, within the range of values reported in literature, indicate that densities of metastable and resonant levels grow along the plasma column

Isabel Santiago; MarÍa Dolores Calzada

2009-01-01

425

Role of dissociative recombination in the excitation kinetics of an argon microwave plasma at atmospheric pressure  

Microsoft Academic Search

A collisional radiative model was developed in order to investigate the influence of dissociative recombination on the Saha-Boltzmann plasma equilibrium. As the dissociative recombination products are not well known, their relative importance was tested through comparison with the distribution of line intensities obtained in a microwave argon discharge produced at atmospheric pressure by a surface wave. It was found that

A. Sáinz; J. Margot; M. C. García; M. D. Calzada

2005-01-01

426

Theoretical Study of Plasma Parameters Dependence on Gas Temperature in an Atmospheric Pressure Argon Microwave Discharge  

Microsoft Academic Search

The gas temperature is an important parameter in many applications of atmospheric pressure microwave discharges (MW). That is why it is necessary to study the influence of that temperature on the plasma characteristics. Our investigation is based on a self-consistent model including the wave electrodynamics and gas-discharge kinetics. We adopt a blocks' energy structure of the argon excited atom. More

M. Pencheva; E. Benova; I. Zhelyazkov

2008-01-01

427

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

428

Generation of microplasma jet at atmospheric pressure using a modified waveguide-based plasma torch  

Microsoft Academic Search

In this study, the microwave-induced microplasma jet was generated at atmospheric pressure using a modified waveguide-based plasma torch. To generate the small size plasma, the fine needle was set at the center of a circular hole made in a wider wall of rectangular waveguide with reduced height. Argon or helium gas was supplied to the free space through the needle.

S. Kanazawa; R. Daidai; S. Akamine; T. Ohkubo

2008-01-01

429

Effect of plasticity and atmospheric pressure on the formation of donut- and croissantlike buckles  

NASA Astrophysics Data System (ADS)

The formation of donut- and croissantlike buckles has been observed onto the free surface of gold thin films deposited on silicon substrates. Numerical simulations clearly evidence that the coupling effect between the atmospheric pressure acting on the free surface and the plastic folding of the ductile film is responsible for the circular blister destabilization and the formation of the donut- and croissantlike buckling patterns.

Hamade, S.; Durinck, J.; Parry, G.; Coupeau, C.; Cimetière, A.; Grilhé, J.; Colin, J.

2015-01-01

430

Development and spectroscopic investigation of a microwave plasma source at atmospheric pressure  

Microsoft Academic Search

Summary form only given.Microwave plasma sources at atmospheric pressure have a variety of different applications. On the one hand they can be used for the treatment of surfaces, for example the activation or cleaning, and on the other hand they can be applied for the conversion of gases, such as the abatement of waste gases or other chemical synthesis. The

M. Leins; A. Schulz; M. Walker; U. Schumacher; U. Stroth

2010-01-01

431

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

432

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 changes in organisms with high specificity. Here we report on a novel combination of infrared laser ablation with electrospray ionization (LAESI) as an ambient ion source for mass spectrometry. As a result

Vertes, Akos

433

Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass Spectrometry  

E-print Network

Chapter 9 Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass Spectrometry Peter Nemes and Akos Vertes Abstract Laser ablation electrospray ionization (LAESI) is a novel-IR) MALDI (3), laser ablation S.S. Rubakhin, J.V. Sweedler (eds.), Mass Spectrometry Imaging, Methods

Vertes, Akos

434

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

435

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

436

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.