Sample records for cold atmospheric pressure

  1. Cold plasma brush generated at atmospheric pressure

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

    A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4W) up to tens of watts (up to 45W). 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 10-15mm in width and less than 1.0mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42°C) when running with a relatively high gas flow rate of about 3500ml/min. For an argon plasma brush, the operating voltage from less than 500V to about 2500V was tested, with an argon gas flow rate varied from less than 1000to3500ml/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.

  2. Atmospheric pressure cold plasma as an antifungal therapy

    NASA Astrophysics Data System (ADS)

    Sun, Peng; Sun, Yi; Wu, Haiyan; Zhu, Weidong; Lopez, Jose L.; Liu, Wei; Zhang, Jue; Li, Ruoyu; Fang, Jing

    2011-01-01

    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.

  3. Cold atmospheric pressure air plasma jet for medical applications

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

    By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2cm 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.

  4. Modification of Glassy Carbon Surfaces by an Atmospheric Pressure Cold Plasma H. Mortensen 1

    E-print Network

    Modification of Glassy Carbon Surfaces by an Atmospheric Pressure Cold Plasma Torch H. Mortensen 1] and is operated in a ventilated box at atmospheric pressure. The powered electrode is a 0.5-mm diameter tungsten of the surfaces is often necessary. Various methods are employed, such as wet chemical or low-pressure plasma

  5. 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...

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

    Microsoft Academic Search

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

    2009-01-01

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

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

    Microsoft Academic Search

    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

    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

  8. Transfer of a cold atmospheric pressure plasma jet through a long flexible plastic tube

    NASA Astrophysics Data System (ADS)

    Kostov, Konstantin G.; Machida, Munemasa; Prysiazhnyi, Vadym; Honda, Roberto Y.

    2015-04-01

    This work proposes an experimental configuration for the generation of a cold atmospheric pressure plasma jet at the downstream end of a long flexible plastic tube. The device consists of a cylindrical dielectric chamber where an insulated metal rod that serves as high-voltage electrode is inserted. The chamber is connected to a long (up to 4?m) commercial flexible plastic tube, equipped with a thin floating Cu wire. The wire penetrates a few mm inside the discharge chamber, passes freely (with no special support) along the plastic tube and terminates a few millimeters before the tube end. The system is flushed with Ar and the dielectric barrier discharge (DBD) is ignited inside the dielectric chamber by a low frequency ac power supply. The gas flow is guided by the plastic tube while the metal wire, when in contact with the plasma inside the DBD reactor, acquires plasma potential. There is no discharge inside the plastic tube, however an Ar plasma jet can be extracted from the downstream tube end. The jet obtained by this method is cold enough to be put in direct contact with human skin without an electric shock. Therefore, by using this approach an Ar plasma jet can be generated at the tip of a long plastic tube far from the high-voltage discharge region, which provides the safe operation conditions and device flexibility required for medical treatment.

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

    PubMed

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

    2014-10-01

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

  10. A Novel Method of Tooth Whitening Using Cold Plasma Microjet Driven by Direct Current in Atmospheric-Pressure Air

    Microsoft Academic Search

    Jie Pan; Peng Sun; Ye Tian; Haixia Zhou; Haiyan Wu; Na Bai; Fuxiang Liu; Weidong Zhu; Jue Zhang; K. H. Becker; Jing Fang

    2010-01-01

    We reported in this paper the tooth-whitening effect by a direct-current cold atmospheric-pressure air plasma microjet (PMJ) and saline solution (0.9%). All teeth were randomly divided into three groups, treated for 20 min with an air blow and saline solution, a PMJ and saline solution, and 35% hydrogen peroxide gel, respectively. Compared with the other groups, the teeth treated with

  11. Tooth Whitening With Hydrogen Peroxide Assisted by a Direct-Current Cold Atmospheric-Pressure Air Plasma Microjet

    Microsoft Academic Search

    Peng Sun; Jie Pan; Ye Tian; Na Bai; Haiyan Wu; Lingxuan Wang; Cailan Yu; Jue Zhang; Weidong Zhu; Kurt H. Becker; Jing Fang

    2010-01-01

    A tooth-whitening process using hydrogen peroxide (H2O2) enhanced by a direct-current cold atmospheric-pressure plasma microjet (PMJ) is presented. Compared with the conventional clinical method of using H2O2 alone, a significant improvement of the tooth-whitening process was observed when the PMJ was used in the process. The tooth-surface temperature was monitored for safety considerations and did not exceed 37°C at a

  12. Atmospheric-Pressure Cold Plasma Induces Transcriptional Changes in Ex Vivo Human Corneas

    PubMed Central

    Rosani, Umberto; Tarricone, Elena; Venier, Paola; Brun, Paola; Deligianni, Velika; Zuin, Matteo; Martines, Emilio

    2015-01-01

    Background Atmospheric pressure cold plasma (APCP) might be considered a novel tool for tissue disinfection in medicine since the active chemical species produced by low plasma doses, generated by ionizing helium gas in air, induces reactive oxygen species (ROS) that kill microorganisms without substantially affecting human cells. Objectives In this study, we evaluated morphological and functional changes in human corneas exposed for 2 minutes (min) to APCP and tested if the antioxidant n-acetyl l-cysteine (NAC) was able to inhibit or prevent damage and cell death. Results Immunohistochemistry and western blotting analyses of corneal tissues collected at 6 hours (h) post-APCP treatment demonstrated no morphological tissue changes, but a transient increased expression of OGG1 glycosylase that returned to control levels in 24 h. Transcriptome sequencing and quantitative real time PCR performed on different corneas revealed in the treated corneas many differentially expressed genes: namely, 256 and 304 genes showing expression changes greater than ± 2 folds in the absence and presence of NAC, respectively. At 6 h post-treatment, the most over-expressed gene categories suggested an active or enhanced cell functioning, with only a minority of genes specifically concerning oxidative DNA damage and repair showing slight over-expression values (<2 folds). Moreover, time-related expression analysis of eight genes up-regulated in the APCP-treated corneas overall demonstrated the return to control expression levels after 24 h. Conclusions These findings of transient oxidative stress accompanied by wide-range transcriptome adjustments support the further development of APCP as an ocular disinfectant. PMID:26203910

  13. Silica nanoparticles treated by cold atmospheric-pressure plasmas improve the dielectric performance of organic-inorganic nanocomposites.

    PubMed

    Yan, Wei; Han, Zhao Jun; Phung, B Toan; Ostrikov, Kostya Ken

    2012-05-01

    We report on the application of cold atmospheric-pressure plasmas to modify silica nanoparticles to enhance their compatibility with polymer matrices. Thermally nonequilibrium atmospheric-pressure plasma is generated by a high-voltage radio frequency power source operated in the capacitively coupled mode with helium as the working gas. Compared to the pure polymer and the polymer nanocomposites with untreated SiO(2), the plasma-treated SiO(2)-polymer nanocomposites show higher dielectric breakdown strength and extended endurance under a constant electrical stress. These improvements are attributed to the stronger interactions between the SiO(2) nanoparticles and the surrounding polymer matrix after the plasma treatment. Our method is generic and can be used in the production of high-performance organic-inorganic functional nanocomposites. PMID:22489667

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

    SciTech Connect

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

    2012-06-18

    To understand plasma-induced chemical processing in liquids, we investigated the formation of free radicals in aqueous solution exposed to different types of non-contact atmospheric-pressure helium plasma using the spin-trapping technique. Both hydroxyl radical (OH{center_dot}) and superoxide anion radical (O{sub 2}{sup -}{center_dot}) adducts were observed when neutral oxygen gas was additionally supplied to the plasma. In particular, O{sub 2}{sup -}{center_dot} can be dominantly induced in the solution via oxygen flow into the afterglow gas of helium plasma. This type of plasma treatment can potentially be used in medical applications to control infectious diseases, because the O{sub 2}{sup -}{center_dot} is crucial for sterilization of liquids via atmospheric-pressure plasma.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  16. 80 mm-wide cold atmospheric-pressure plasma generated by two parallel but horizontally separated electrodes

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Ichiki, Takanori

    2015-04-01

    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.

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

    SciTech Connect

    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

    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)

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    PubMed Central

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

    2014-01-01

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

  1. Atmospheric Pressure Cold Argon/Oxygen Plasma Jet Assisted by Preionization of Syringe Needle Electrode

    NASA Astrophysics Data System (ADS)

    Qian, Muyang; Ren, Chunsheng; Wang, Dezhen; Feng, Yan; Zhang, Jialiang

    2010-10-01

    An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 1017 cm-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.

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

    Microsoft Academic Search

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  4. Novel AC and DC Non-Thermal Plasma Sources for Cold Surface Treatment of Polymer Films and Fabrics at Atmospheric Pressure

    Microsoft Academic Search

    Yuri Akishev; Michail Grushin; Anatoly Napartovich; Nikolay Trushkin

    2002-01-01

    Novel types of non-thermal plasma sources at atmospheric pressure based on multi-pin DC (direct current) diffusive glow discharge and AC (alternative current) streamer barrier corona have been elaborated and tested successfully for cold surface treatment of polymer films [polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET),] and polyester fabric. Results on physical properties ofdischarges mentioned and output energy characteristics of new

  5. 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

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

    PubMed

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

    2015-01-01

    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

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

    SciTech Connect

    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

    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.

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

    PubMed

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

    2012-05-01

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

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

    SciTech Connect

    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

    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.

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

    PubMed Central

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

    2013-01-01

    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

  11. 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

    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

    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. %.

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

    PubMed Central

    Matthes, Rutger; Assadian, Ojan; Kramer, Axel

    2014-01-01

    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

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

    SciTech Connect

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

    2010-06-15

    An atmospheric-pressure Ar/O{sub 2} glow discharge is generated in a parallel bare metal plate reactor with a radio-frequency power supply by introducing a dielectric strip in the inlet of the gas flow. The role of the dielectric strip is discussed experimentally. The allowable oxygen-to-argon ratio reaches 1.0 vol % and the generated Ar/O{sub 2} plasma discharge is characterized by a low gas temperature and good spatial homogeneity, implying its feasible application as a type of material treatment for a large-area surface, as illustrated experimentally by the ashing of carbon black.

  14. Pseudomonas aeruginosa Biofilm Response and Resistance to Cold Atmospheric Pressure Plasma Is Linked to the Redox-Active Molecule Phenazine

    PubMed Central

    Mai-Prochnow, Anne; Bradbury, Mark; Ostrikov, Kostya; Murphy, Anthony B.

    2015-01-01

    Pseudomonas aeruginosa is an important opportunistic pathogen displaying high antibiotic resistance. Its resistance is in part due to its outstanding ability to form biofilms on a range of biotic and abiotic surfaces leading to difficult-to-treat, often long-term infections. Cold atmospheric plasma (CAP) is a new, promising antibacterial treatment to combat antibiotic-resistant bacteria. Plasma is ionized gas that has antibacterial properties through the generation of a mix of reactive oxygen and nitrogen species (RONS), excited molecules, charged particles and UV photons. Our results show the efficient removal of P. aeruginosa biofilms using a plasma jet (kINPen med), with no viable cells detected after 5 min treatment and no attached biofilm cells visible with confocal microscopy after 10 min plasma treatment. Because of its multi-factorial action, it is widely presumed that the development of bacterial resistance to plasma is unlikely. However, our results indicate that a short plasma treatment (3 min) may lead to the emergence of a small number of surviving cells exhibiting enhanced resistance to subsequent plasma exposure. Interestingly, these cells also exhibited a higher degree of resistance to hydrogen peroxide. Whole genome comparison between surviving cells and control cells revealed 10 distinct polymorphic regions, including four belonging to the redox active, antibiotic pigment phenazine. Subsequently, the interaction between phenazine production and CAP resistance was demonstrated in biofilms of transposon mutants disrupted in different phenazine pathway genes which exhibited significantly altered sensitivity to CAP. PMID:26114428

  15. Pseudomonas aeruginosa Biofilm Response and Resistance to Cold Atmospheric Pressure Plasma Is Linked to the Redox-Active Molecule Phenazine.

    PubMed

    Mai-Prochnow, Anne; Bradbury, Mark; Ostrikov, Kostya; Murphy, Anthony B

    2015-01-01

    Pseudomonas aeruginosa is an important opportunistic pathogen displaying high antibiotic resistance. Its resistance is in part due to its outstanding ability to form biofilms on a range of biotic and abiotic surfaces leading to difficult-to-treat, often long-term infections. Cold atmospheric plasma (CAP) is a new, promising antibacterial treatment to combat antibiotic-resistant bacteria. Plasma is ionized gas that has antibacterial properties through the generation of a mix of reactive oxygen and nitrogen species (RONS), excited molecules, charged particles and UV photons. Our results show the efficient removal of P. aeruginosa biofilms using a plasma jet (kINPen med), with no viable cells detected after 5 min treatment and no attached biofilm cells visible with confocal microscopy after 10 min plasma treatment. Because of its multi-factorial action, it is widely presumed that the development of bacterial resistance to plasma is unlikely. However, our results indicate that a short plasma treatment (3 min) may lead to the emergence of a small number of surviving cells exhibiting enhanced resistance to subsequent plasma exposure. Interestingly, these cells also exhibited a higher degree of resistance to hydrogen peroxide. Whole genome comparison between surviving cells and control cells revealed 10 distinct polymorphic regions, including four belonging to the redox active, antibiotic pigment phenazine. Subsequently, the interaction between phenazine production and CAP resistance was demonstrated in biofilms of transposon mutants disrupted in different phenazine pathway genes which exhibited significantly altered sensitivity to CAP. PMID:26114428

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

    NASA Astrophysics Data System (ADS)

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

    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

  17. Effects and Mechanism of Atmospheric-Pressure Dielectric Barrier Discharge Cold Plasma on Lactate Dehydrogenase (LDH) Enzyme.

    PubMed

    Zhang, Hao; Xu, Zimu; Shen, Jie; Li, Xu; Ding, Lili; Ma, Jie; Lan, Yan; Xia, Weidong; Cheng, Cheng; Sun, Qiang; Zhang, Zelong; Chu, Paul K

    2015-01-01

    Proteins are carriers of biological functions and the effects of atmospheric-pressure non-thermal plasmas on proteins are important to applications such as sterilization and plasma-induced apoptosis of cancer cells. Herein, we report our detailed investigation of the effects of helium-oxygen non-thermal dielectric barrier discharge (DBD) plasmas on the inactivation of lactate dehydrogenase (LDH) enzyme solutions. Circular dichroism (CD) and dynamic light scattering (DLS) indicate that the loss of activity stems from plasma-induced modification of the secondary molecular structure as well as polymerization of the peptide chains. Raising the treatment intensity leads to a reduced alpha-helix content, increase in the percentage of the beta-sheet regions and random sequence, as well as gradually decreasing LDH activity. However, the structure of the LDH plasma-treated for 300 seconds exhibits a recovery trend after storage for 24?h and its activity also increases slightly. By comparing direct and indirect plasma treatments, plasma-induced LDH inactivation can be attributed to reactive species (RS) in the plasma, especially ones with a long lifetime including hydrogen peroxide, ozone, and nitrate ion which play the major role in the alteration of the macromolecular structure and molecular diameter in lieu of heat, UV radiation, and charged particles. PMID:25992482

  18. Cold-air atmospheric pressure plasma against Clostridium difficile spores: a potential alternative for the decontamination of hospital inanimate surfaces.

    PubMed

    Claro, Tânia; Cahill, Orla J; O'Connor, Niall; Daniels, Stephen; Humphreys, Hilary

    2015-06-01

    Clostridium difficile spores survive for months on environmental surfaces and are highly resistant to decontamination. We evaluated the effect of cold-air plasma against C. difficile spores. The single-jet had no effect while the multi-jet achieved 2-3 log10 reductions in spore counts and may augment traditional decontamination. PMID:25782039

  19. Atmospheric Pressure Glow Discharges

    SciTech Connect

    Graham, W. G.; Nersisyan, G. [International Research Centre for Experimental Physics, Queens University Belfast, BT7 1NN, Northern Ireland (United Kingdom)

    2006-12-01

    Their relative engineering simplicity, plasma uniformity and chemistry make Atmospheric Pressure Glow Discharges (APGD) very attractive for plasma processing applications. Here some of the basic characteristics of glow discharges are introduced. The basic dielectric barrier discharge and how it can be operated in a uniform glow rather filamentary mode is described. Electrical and laser-based measurements that throw light on the underlying physics of APGDs are presented, along with a model which seeks to explore the plasma chemistry of these discharges.

  20. DC powered atmospheric pressure micro-plasmajet for biomedical applications

    Microsoft Academic Search

    J. F. Kolb; R. O. Price; A.-A. H. Mohamed; K. H. Schoenbach

    2006-01-01

    Summary form only given. Nonthermal (cold) plasmas operated in air at atmospheric pressure offer an appealing method for the processing and decontamination of surfaces. Most existing devices are operated with radiofrequency high voltages. Microhollow cathode discharges (MHCDs), on the other hand, allow us to generate a direct current driven plasma jet in atmospheric pressure gases, including air. The discharge is

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

    Microsoft Academic Search

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

    2011-01-01

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

  2. Atmospheric Pressure Indicator.

    ERIC Educational Resources Information Center

    Salzsieder, John C.

    1995-01-01

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

  3. Constraints on Early Mars atmospheric pressure

    E-print Network

    Kite, Edwin

    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

  4. Cold winters and the relation to atmospheric blocking

    E-print Network

    de Vries, Hylke

    Cold winters and the relation to atmospheric blocking Hylke de Vries De Bilt, 2011 | Technical report; TR-324 #12;#12;Cold winters and the relation to atmospheric blocking Versie 1.0 Datum 12 september 2011 Status Definitief #12;#12;COLD WINTERS AND THE RELATION TO ATMOSPHERIC BLOCKING HYLKE DE

  5. An atmospheric pressure plasma source

    Microsoft Academic Search

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

    2000-01-01

    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

  6. Atmospheric Pressure During Landing

    NASA Technical Reports Server (NTRS)

    1997-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  8. Atmospheric Pressure Mass Spectrometry: A New Analytical

    E-print Network

    Seitzinger, Sybil

    Atmospheric Pressure Mass Spectrometry: A New Analytical Chemical Characterization Method climate, air quality, and ecosystem processes. Atmospheric pressure electrospray ionization mass, Piscataway, New Jersey 08854-8058 The complex mixture of organic compounds in the atmosphere influences

  9. Cold Atmosphere Plasma in Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Keidar, Michael

    2012-10-01

    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

  10. Chaotic cold accretion on to black holes in rotating atmospheres

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Brighenti, F.; Temi, P.

    2015-07-01

    The fueling of black holes is one key problem in the evolution of baryons in the universe. Chaotic cold accretion (CCA) profoundly differs from classic accretion models, as Bondi and thin disc theories. Using 3D high-resolution hydrodynamic simulations, we now probe the impact of rotation on the hot and cold accretion flow in a typical massive galaxy. In the hot mode, with or without turbulence, the pressure-dominated flow forms a geometrically thick rotational barrier, suppressing the black hole accretion rate to ~1/3 of the spherical case value. When radiative cooling is dominant, the gas loses pressure support and quickly circularizes in a cold thin disk; the accretion rate is decoupled from the cooling rate, although it is higher than that of the hot mode. In the more common state of a turbulent and heated atmosphere, CCA drives the dynamics if the gas velocity dispersion exceeds the rotational velocity, i.e., turbulent Taylor number Tat< 1. Extended multiphase filaments condense out of the hot phase via thermal instability (TI) and rain toward the black hole, boosting the accretion rate up to 100 times the Bondi rate (?• ~ ?cool). Initially, turbulence broadens the angular momentum distribution of the hot gas, allowing the cold phase to condense with prograde or retrograde motion. Subsequent chaotic collisions between the cold filaments, clouds, and a clumpy variable torus promote the cancellation of angular momentum, leading to high accretion rates. As turbulence weakens (Tat > 1), the broadening of the distribution and the efficiency of collisions diminish, damping the accretion rate ? Tat-1, until the cold disk drives the dynamics. This is exacerbated by the increased difficulty to grow TI in a rotating halo. The simulated sub-Eddington accretion rates cover the range inferred from AGN cavity observations. CCA predicts inner flat X-ray temperature and r-1 density profiles, as recently discovered in M 87 and NGC 3115. The synthetic H? images reproduce the main features of cold gas observations in massive ellipticals, as the line fluxes and the filaments versus disk morphology. Such dichotomy is key for the long-term AGN feedback cycle. As gas cools, filamentary CCA develops and boosts AGN heating; the cold mode is thus reduced and the rotating disk remains the sole cold structure. Its consumption leaves the atmosphere in hot mode with suppressed accretion and feedback, reloading the cycle.

  11. Laser electrospray mass spectrometry of adsorbed molecules at atmospheric pressure

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  12. Atmospheric-pressure guided streamers for liposomal membrane disruption

    SciTech Connect

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

    2012-12-24

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

  13. 2009-2010 Cold Season National Oceanic and Atmospheric Administration

    E-print Network

    2009-2010 Cold Season National Oceanic and Atmospheric Administration National Climatic Data Center 2009/2010 Cold Season Significant Events Note: Data in this report are compiled from preliminary statistics Updated May 24, 2010 Cold Season Overview The purpose of this special report is to provide

  14. Atmospheric durability of polymer-fiber composites in cold climates

    Microsoft Academic Search

    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

    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

  15. Sterilization effects of atmospheric cold plasma brush

    SciTech Connect

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

    2006-01-02

    This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0x10{sup 4}-1.0x10{sup 5} Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar+O{sub 2} plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy.

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

    E-print Network

    Zexian, Cao

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

  17. Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets

    SciTech Connect

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

    2006-04-24

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

  18. Does low atmospheric pressure independently trigger migraine?

    PubMed

    Bolay, Hayrunnisa; Rapoport, Alan

    2011-10-01

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

  19. Atmospheric pressure plasmas: A review

    Microsoft Academic Search

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

    2006-01-01

    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

  20. Contact-free cold atmospheric plasma treatment of Deinococcus radiodurans.

    PubMed

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

    2012-09-01

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

  1. Shuttle Orbiter Atmospheric Revitalization Pressure Control Subsystem

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  2. Optical diagnostics of atmospheric pressure air plasmas

    Microsoft Academic Search

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

    2003-01-01

    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

  3. LOSS-OF-PRESSURE ACCIDENT. COLD LEG PIPING FAILURE

    Microsoft Academic Search

    Landoni

    1960-01-01

    The differential pressure across the reactor core and the steam ; generator and blower in the sound loop in the event of a circumferential piping ; rupture at the cold leg isolation valve followed by complete displacement of the ; severed pipe ends is determined. The effect of quickopening valves in the ; coolant loop bypass lines upon the pressure

  4. Physics and medical applications of cold atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Keidar, Michael

    2013-09-01

    Recent progress in atmospheric plasmas led to the creation of cold plasmas with ion temperature close to room temperature. Varieties of novel plasma diagnostic techniques were applied in a quest to understand physics of cold plasmas. In particular it was established that the streamer head charge is about 108 electrons, the electrical field in the head vicinity is about 107 V/m, and the electron density of the streamer column is about 1019 m3. We have demonstrated the efficacy of cold plasma in a pre-clinical model of various cancer types (lung, bladder, breast, head, neck, brain and skin). Both in-vitro andin-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. (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 plasmainduces a 2-fold increase in cells at the G2/M-checkpoint in both papilloma and carcinoma cells at ~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.

  5. Pressure field study of the Tevatron cold compressors

    SciTech Connect

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

    2003-01-01

    The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations [1]. The compressor is designed to pump 60 g/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g/sec. Operating speeds are between 40 and 95 krpm, with a speed of 80 krpm at the design point. Different heat loads and magnet quench performance of each of the twenty-four satellite refrigerators dictates different process pressure and flow rates of the cold compressors. Reducing the process flow rate can cause the centrifugal cold compressor to stop pumping and subsequently surge. Tests have been conducted at the Cryogenic Test Facility at Fermilab to map the pressure field and appropriate efficiency of the IHI hydrodynamic cold compressor. The information allows tuning of each of the twenty-four Tevatron satellite refrigerators to avoid cold compressor operation near the surge and choke lines. A new impeller has also been tested. The Tevatron cold compressor pressure field and efficiency data with the new impeller are presented in this paper.

  6. Pressure Field Study of the Tevatron Cold Compressors

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

    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.

  7. Pressure Field Study of the Tevatron Cold Compressors

    SciTech Connect

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

    2004-06-23

    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.

  8. Atmospheric Pressure Plasma Process And Applications

    SciTech Connect

    Peter C. Kong; Myrtle

    2006-09-01

    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.

  9. Stability Measurements of an Atmospheric Pressure Arc

    Microsoft Academic Search

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

    1996-01-01

    Experiments on the stability of atmospheric pressure arcs have been started at PPPL to understand and improve the performance of arc furnaces used for processing applications in metallurgy and hazardous waste treatment. Previous studies have suggested that the violent instabilities in such arcs may be due to kink modes (P. M. Bellan and J. W. Higley. IEEE Trans. Plasma Sci.,

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

    NASA Technical Reports Server (NTRS)

    Johnson, D. L.

    1975-01-01

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

  11. Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry

    E-print Network

    Vertes, Akos

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

  12. Large area atmospheric-pressure plasma jet

    DOEpatents

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  14. Atmospheric cold plasma jet for plant disease treatment

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  15. Special issue: diagnostics of atmospheric pressure microplasmas

    NASA Astrophysics Data System (ADS)

    Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

    2013-11-01

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

  16. Martian Atmospheric Pressure Static Charge Elimination Tool

    NASA Technical Reports Server (NTRS)

    Johansen, Michael R.

    2014-01-01

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

  17. [Spectral investigation of atmospheric pressure plasma column].

    PubMed

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

    2012-07-01

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

  18. Pressure Field Study of the Tevatron Cold Compressors

    Microsoft Academic Search

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

    2004-01-01

    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

  19. Pressure field study of the Tevatron cold compressors

    Microsoft Academic Search

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

    2003-01-01

    The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations [1]. The compressor is designed to pump 60 g\\/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g\\/sec. Operating speeds are between 40 and 95 krpm, with

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

    Microsoft Academic Search

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

    2003-01-01

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

  1. Study on an Atmospheric Pressure Plasma Jet and its Application in Etching Photo-Resistant Materials

    Microsoft Academic Search

    Haijiang Li; Shouguo Wang; Lingli Zhao; Tianchun Ye

    2004-01-01

    An atmospheric pressure radio-frequency plasma jet that can eject cold plasma has been developed. In this paper, the configuration of this type of plasma jet is illustrated and its discharge characteristics curves are studied with a current and a voltage probe. A thermal couple is used to measure the temperature distribution along the axis of the jet stream. The temperature

  2. The thermal pressure distribution of a simulated cold neutral medium

    SciTech Connect

    Gazol, Adriana, E-mail: a.gazol@crya.unam.mx [Centro de Radioastronomía y Astrofísica, UNAM, A. P. 3-72, c.p. 58089 Morelia, Michoacán (Mexico)

    2014-07-01

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

  3. Biomedical Applications of the Cold Atmospheric Plasma: Cell Responses

    NASA Astrophysics Data System (ADS)

    Volotskova, Olga

    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.

  4. Atmospheric pressure scanning transmission electron microscopy

    SciTech Connect

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

    2010-01-01

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

  5. Atmospheric Cold Fronts Affecting Cold-Water Corals in the Deep Straits of Florida

    NASA Astrophysics Data System (ADS)

    Eberli, G. P.; Grasmueck, M.; Bang, I.; Mooers, C. N.; Viggiano, D.

    2007-12-01

    The Straits of Florida (SoF) are considered an ideal habitat for cold-water corals with the north flowing Florida Current (FC) providing a continuous supply of food. The FC does, however, not fill the entire Straits and deep, opposing undercurrents and coastal countercurrents occur off Florida and the Bahamas. New observational and model data document that, in addition to the well-known perturbation of upper ocean currents by atmospheric cold front passages, the near-bottom current field in the SoF is also repeatedly perturbed by atmospheric cold fronts none of which is reflected in the cold-water mound morphology. Measurements of the near-bottom flow field by an Autonomous Underwater Vehicle (AUV), cruising 40 m above sea floor at five coral mound fields ranging from 14-48 km2 in 590-875 m water in December 2005, record a complicated current pattern in space and time. Near-bottom currents are bi-directional, dominated by semi- diurnal tides, on the lower slopes of the Bahamas where mounds form kilometer long ridges as high as 120 m. Near-bottom currents flow north in the middle of Straits but generally south along the Miami Terrace. The mound morphology varies widely between sites and no obvious (i.e., direct, linear) correlation exists between current strength and mound height. The 12 to 48 h AUV observational data at each site compare well with results of the quasi-operational 3D ocean circulation model EFSIS (East Florida Shelf Information System). The Model enables the analysis of the bottom currents over extended periods and confirms that the near-bottom flow field in the SoF is highly variable on time scales ranging from 6 hours to several days, with magnitudes of +/- 0.2 to 0.6 m/s, depending upon location. During the observation period of December 2005, a recurring current variability is due to a sequence of deep cyclonic eddies that originate approximately every ten days near Cay Sal Bank and move northward on the eastern side of the FC. Offshore Bimini, where the SoF narrows and shoals, and the FC accelerates, the near-bottom eddies intensify and start to move westward. When reaching the Miami Terrace the eddies occupy the entire water column. The timing of the eddies correlate remarkably well with the passage of atmospheric cold fronts. During cold front passages the FC axis is displaced offshore the Florida Keys. A probable mechanism for the generation of the near bottom cyclones is the interaction of FC meanders with Cay Sal Bank. The impact of these "cold-front" perturbations on the deep-water coral communities remains to be quantitatively assessed.

  6. Atmospheric-pressure Penning ionization mass spectrometry.

    PubMed

    Hiraoka, Kenzo; Fujimaki, Susumu; Kambara, Shizuka; Furuya, Hiroko; Okazaki, Shigemitsu

    2004-01-01

    A preliminary study on the atmospheric-pressure Penning ionization (APP(e)I) of gaseous organic compounds with Ar* has been made. The metastable argon atoms (Ar*: 11.55 eV for (3)P(2) and 11.72 eV for (3)P(0)) were generated by the negative-mode corona discharge of atmospheric-pressure argon gas. By applying a high positive voltage (+500 to +1000 V) to the stainless steel capillary for the sample introduction (0.1 mm i.d., 0.3 mm o.d.), strong ion signals could be obtained. The ions formed were sampled through an orifice into the vacuum and mass-analyzed by an orthogonal time-of-flight mass spectrometer. The major ions formed by APP(e)I are found to be molecular-related ions for alkanes, aromatics, and oxygen-containing compounds. Because only the molecules with ionization energies less than the internal energy of Ar* are ionized, the present method will be a selective and highly sensitive interface for gas chromatography/mass spectrometry. PMID:15384154

  7. Targeting the cancer cell cycle by cold atmospheric plasma

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Nesman, Tomas E.

    2001-01-01

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

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

    Microsoft Academic Search

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

    1994-01-01

    Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is

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

    Microsoft Academic Search

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

    2008-01-01

    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

  11. Response of cyanobacteria to low atmosphere pressure

    NASA Astrophysics Data System (ADS)

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

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

  12. How water contributes to pressure and cold denaturation of proteins

    E-print Network

    Bianco, Valentino

    2015-01-01

    The mechanisms of cold- and pressure-denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.

  13. How water contributes to pressure and cold denaturation of proteins

    E-print Network

    Valentino Bianco; Giancarlo Franzese

    2015-05-28

    The mechanisms of cold- and pressure-denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.

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

    PubMed

    Hoffmann, Clotilde; Berganza, Carlos; Zhang, John

    2013-01-01

    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

  15. Radiation pressure driving of a dusty atmosphere

    E-print Network

    Tsang, Benny Tsz-Ho

    2015-01-01

    Radiation pressure can be dynamically important in certain star-forming environments such as ultra-luminous infrared and submillimeter galaxies. Whether and how radiation drives turbulence and bulk outflows in star formation sites is still unclear. The uncertainty stems from the limitations of direct numerical schemes used to simulate radiation transfer and radiation-gas coupling. The idealized setup in which radiation is introduced at the base of a dusty atmosphere in a gravitational field has recently become a standard for the testing of radiation hydrodynamics methods in the context of star formation. To a series of treatments enlisting the flux-limited-diffusion approximation as well as a short-characteristics tracing and M1 closure for the variable Eddington tensor approximation, we here add another, very different treatment based on the Implicit Monte Carlo radiation transfer scheme. Consistent with all previous treatment, we observe Rayleigh-Taylor instability and a readjustment to a near-Eddington sta...

  16. THE REMARKABLE HIGH PRESSURE OF THE LOCAL LEO COLD CLOUD

    SciTech Connect

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

    2012-06-20

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

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

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    1989-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Ingersoll, A. P.

    1989-10-01

    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.

  19. A global mechanism creating low atmospheric luminous cold plasmas

    NASA Astrophysics Data System (ADS)

    Gitle Hauge, Bjørn; Petter Strand, Erling

    2014-05-01

    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.

  20. Cold Atmospheric Plasma as an alternative therapy for cancer therapies

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  1. The effect of atmospheric pressure on ventricular assist device output.

    PubMed

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

    2012-03-01

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

  2. Nitric oxide generated by atmospheric pressure air microplasma

    Microsoft Academic Search

    Keita Matsuo; Hidekazu Yoshida; Jaegu Choi; S. Hamid; R. Hosseini; Takao Namihira; Sunao Katsuki; Hidenori Akiyama

    2009-01-01

    The production of atmospheric pressure air microplasma jet requires no vacuum devices and it uses air gas, which considerably reduces the investment cost. Atmospheric pressure microplasma jets have recently been used for industrial and medical applications, such as local dental treatment, inner surface treatment of capillaries, stimuli of microorganisms, and local cleaning of semiconductor devices. The other advantage of the

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

    E-print Network

    Goodman, Wayne

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

  4. Generation of Integrated Atmospheric-Pressure Microplasmas

    NASA Astrophysics Data System (ADS)

    Taniguchi, Kazutake; Fukasawa, Takayuki; Yoshiki, Hiroyuki; Horiike, Yasuhiro

    2003-10-01

    This work is based on the motivation that by integrating microplasmas confined in a small volume, a large area high-density plasma source could be developed. Firstly, He gas microplasmas were generated by capacitively coupled plasma (CCP) and inductively coupled type plasma (ICP-type) in single small diameter ceramic tubes supplied with 13.56 MHz power via electrodes. Then, based upon the obtained characteristics, sustaining voltage and RF power variations were discussed for integrating tubes two and three dimensionally. However, the presence of the CCP component was noticed from the weak discharge around the center of the highly integrated ICP-type. Therefore, the generation of planar-type plasma was also studied using narrow comb electrodes, which enabled us to produce the discharge at a lower voltage in accordance with Paschen’s law. As a result, uniform plasma was successfully generated in an area of 12 mm× 12 mm. Atmospheric-pressure microplasma generation of pure N2 gas as well as He gas was realized by planar type plasma at low sustaining voltages.

  5. Laser induced fluorescence in atmospheric pressure discharges

    NASA Astrophysics Data System (ADS)

    Dilecce, G.; Martini, L. M.; Tosi, P.; Scotoni, M.; De Benedictis, S.

    2015-06-01

    This paper offers an outline of laser induced fluorescence (LIF) diagnostics and practical recommendations for its use in atmospheric pressure discharges. LIF principles, technical requirements and rationalization of experimental outcomes by modelling are addressed. Important issues that are particularly relevant to small scale, spatially inhomogeneous discharges, like plasma-jets, are emphasized. For the first time, all collision processes and the spatial non-homogeneity of the laser beam are together accounted for in the LIF model. Saturation characteristics are discussed and used for the assessment of model parameters. A calibration procedure is discussed and implemented. Gas temperature measurements by LIF are also addressed. The whole description of the technique is given, without loss of generality, through the example of its application to the OH radical. Notes on other diatomic radicals, CH, NO and CN, are given along the paper. Some results in a RF plasma-jet are presented as an example of application in a discharge system where all the concepts developed in the paper are applied.

  6. Tooth bleaching with nonthermal atmospheric pressure plasma.

    PubMed

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

    2009-04-01

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

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

    Microsoft Academic Search

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

    2008-01-01

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

  8. Atmospheric Pressure Non-Thermal Air Plasma Jet

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam; Al-Mashraqi, Ahmed; Benghanem, Mohamed; Al Shariff, Samir

    2013-09-01

    Atmospheric pressure air cold plasma jet is introduced in this work. It is AC (60 Hz to 20 kHz) cold plasma jet in air. The system is consisted of a cylindrical alumina insulator tube with outer diameter of 1.59 mm and 26 mm length and 0.80 mm inner diameter. AC sinusoidal high voltage was applied to the powered electrode which is a hollow needle inserted in the Alumina tube. The inner electrode is a hollow needle with 0.80 mm and 0.46 mm outer and inner diameters respectively. The outer electrode is grounded which is a copper ring surrounded the alumina tube locates at the nozzle end. Air is blowing through the inner electrode to form a plasma jet. The jet length increases with flow rate and applied voltage to reach 1.5 cm. The gas temperature decreases with distance from the end of the nozzle and with increasing the flow rate. The spectroscopic measurement between 200 nm and 900 nm indicates that the jet contains reactive species such as OH, O in addition to the UV emission. The peak to peak current values increased from 6 mA to 12 mA. The current voltage waveform indicates that the generated jet is homogenous plasma. The jet gas temperature measurements indicate that the jet has a room temperature. Atmospheric pressure air cold plasma jet is introduced in this work. It is AC (60 Hz to 20 kHz) cold plasma jet in air. The system is consisted of a cylindrical alumina insulator tube with outer diameter of 1.59 mm and 26 mm length and 0.80 mm inner diameter. AC sinusoidal high voltage was applied to the powered electrode which is a hollow needle inserted in the Alumina tube. The inner electrode is a hollow needle with 0.80 mm and 0.46 mm outer and inner diameters respectively. The outer electrode is grounded which is a copper ring surrounded the alumina tube locates at the nozzle end. Air is blowing through the inner electrode to form a plasma jet. The jet length increases with flow rate and applied voltage to reach 1.5 cm. The gas temperature decreases with distance from the end of the nozzle and with increasing the flow rate. The spectroscopic measurement between 200 nm and 900 nm indicates that the jet contains reactive species such as OH, O in addition to the UV emission. The peak to peak current values increased from 6 mA to 12 mA. The current voltage waveform indicates that the generated jet is homogenous plasma. The jet gas temperature measurements indicate that the jet has a room temperature. This work was supported by the National Science, Technology and Innovation Plan(NSTIP) through the Science and Technology Unit (STU) at Taibah University, Al Madinah Al Munawwarah, KSA, with the grant number 08-BIO24-5.

  9. Dry reforming of methane in an atmospheric pressure plasma fluidized bed with Ni\\/?-Al 2O 3 catalyst

    Microsoft Academic Search

    Qi Wang; Yi Cheng; Yong Jin

    2009-01-01

    The synergetic effect of catalyst and cold plasma on dry reforming of methane was investigated in a plasma fluidized bed with Ni\\/?-Al2O3 catalyst. As a comparison, the experiments in the plasma packed bed were also carried out. The cold plasma was generated by the dielectric barrier discharge (DBD) at atmospheric pressure. Both contact modes between plasma and catalytic particles promoted

  10. Cold atmospheric plasma - A new technology for spacecraft component decontamination

    NASA Astrophysics Data System (ADS)

    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

    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.

  11. Department of Mechanical Engineering Spring 2012 Cold Box Pressure Relief Device

    E-print Network

    Demirel, Melik C.

    PENNSTATE Department of Mechanical Engineering Spring 2012 Cold Box Pressure Relief Device Overview A cold box is a structural container used in the industrial gases industry. The main purpose of a box are released into the box if internal equipment leaks. A rapid increase in pressure may cause the box

  12. The relationship between pressure ulcers and skin blood flow response after a local cold provocation

    Microsoft Academic Search

    Rob J. van Marum; Jan H. Meijer; Miel W. Ribbe

    2002-01-01

    van Marum RJ, Meijer JH, Ribbe MW. The relationship between pressure ulcers and skin blood flow response after a local cold provocation. Arch Phys Med Rehabil 2002;83;40-3. Objective: To study the relationship between an impaired blood flow response after a local cold stimulus, testing nerve regulation of the local blood flow response, and an increased risk of developing pressure ulcers.

  13. Characterization of HOCl using atmospheric pressure ionization mass spectrometry

    Microsoft Academic Search

    Tracy E. Caldwell; K. L. Foster; Thorsten Benter; Sarka Langer; John C. Hemminger; Barbara J. Finlayson-Pitts

    1999-01-01

    HOCl is an important intermediate in stratospheric and tropospheric chemistry. Although it can be readily measured in laboratory systems at low pressures (â¤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

  14. Organic thin film deposition in atmospheric pressure glow discharge

    NASA Astrophysics Data System (ADS)

    Okazaki, S.; Kogoma, M.; Yokoyama, T.; Kodama, M.; Nomiyama, H.; Ichinohe, K.

    1996-01-01

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

  15. Atmospheric Pressure Plasmas for Decontamination of Complex Medical Devices

    NASA Astrophysics Data System (ADS)

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

    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.

  16. Reduction of surface gravity data from global atmospheric pressure loading

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  17. Cold atmospheric plasma sterilization: from bacteria to biomolecules

    NASA Astrophysics Data System (ADS)

    Kong, Michael

    2009-10-01

    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.

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

    E-print Network

    Vertes, Akos

    Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals. In this contribution, we explore the feasibility of laser ablation atmospheric pressure photoionization (LAAPPI technique, laser ablation atmospheric pressure photoionization (LAAPPI),[12] for MSI. For microsampling

  19. Visualization of a Copper Wire Explosion in Atmospheric Pressure Air

    E-print Network

    Jadidian, Jouya

    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 ...

  20. Analysis of Sterilization Effect of Atmospheric Pressure Pulsed Plasma

    SciTech Connect

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

    2007-04-23

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

  1. 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.

  2. Nitrogen Atmospheric Pressure Post Discharges for Surface Biological Decontamination inside

    E-print Network

    Paris-Sud XI, Université de

    Nitrogen Atmospheric Pressure Post Discharges for Surface Biological Decontamination inside Small) (PET) capillary tubes of different shapes and lengths and decontamination of flow tubes, both for several years at the Orsay Plasma Lab. Its biological decontamination efficiency has been demonstrated

  3. Measuring Viscosities of Gases at Atmospheric Pressure

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  4. Atmospheric control in purged positive pressure gloveboxes

    Microsoft Academic Search

    W. C. Jr

    1988-01-01

    The gloveboxes in this discussion are used for machining material that must be handled in an inert atmosphere at the Oak Ridge Y-12 Plant. The enclosures are approximately 300 cubic feet in volume and house two precision cutting machines. The machine's shafts penetrate a flexible rubber boot so that the machining area is within the glovebox. Air bearings around the

  5. Modelling Potential Fishery Pressures Facing Western Scotland's Cold Water Coral Reefs 

    E-print Network

    Broughton, Caroline

    2014-11-27

    Cold water coral reefs are of enormous importance to science and society, being hotspots of biodiversity, indicators of past climate and a potential source of new medicines. However, their existence is under threat from pressures including climate...

  6. Eradication of Bacterial Biofilms Using Atmospheric Pressure Non-Thermal Plasmas

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  9. Arctic atmospheric circulation patterns responsible for dry and cold air inflows to the Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Post, Piia; Sepp, Mait

    2015-04-01

    Essential changes have taken place in atmospheric circulation over the Northern Atlantic in winter and spring during the second half of the 20th century. The winter temperature rise in Europe is frequently attributed to the intensification of zonal flow on the Northern Atlantic region and the same is valid for the Baltic Sea region. Intensification of zonal circulation and its expression through NAO and AO indices have been thoroughly studied, but less is known about mechanisms causing declination from the zonality of flow. Extremely cold weather in winter and spring in Baltic Sea region is related to the radiative cooling or advection of cold air masses. In both cases, the typical western flow is blocked and the region is directly influenced by atmospheric circulation conditions in the Arctic through the cold air advection events. Our aim is to study which large scale atmospheric circulation patterns are responsible for this kind of cold air advection to the Baltic Sea region in winter and spring (from December to May). The second task is to identify if this kind of circulation has become less frequent in the region under research beginning from the last half of the 20th century till now. Describing the atmospheric circulation patterns we use several classifications of atmospheric circulation on daily level. The domain of the classifications covers Atlantic-European sector of the Arctic, including area between Greenland and Novaya Zemlya archipelago. Manual classifications by Vangengeim-Girs and Dzerdzejevski are used, but also several newly calculated ones, that apply different classification methods from cost733class software. For the latter ones geopotential height fields at 500 hPa level from NCEP-NCAR reanalysis are classified for the period 1948-2013. The cold air advection events are determined by daily temperature drops by at least 3°C during 24 hours. The circulation types that bring advection of cold Arctic air to the Baltic Sea region are analysed in detail.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  11. Statistical analysis of ionosphere parameters and atmospheric pressure correlations

    NASA Astrophysics Data System (ADS)

    Voloskov, Dmitriy; Bochkarev, Vladimir; Maslennikova, Yulia; Zagidullin, Bulat

    Ionosphere parameters such as Total electron content (TEC) and Doppler frequency shift characterize ionosphere influence on signals propagation, and therefore information about these parameters is important for radio communication tasks. Meteorological effects such as atmospheric pressure variations can influence on ionosphere parameters. This work is dedicated to analysis of correlations between meteorological and ionosphere parameters. NCEP/NCAR reanalysis meteorological maps, Jet Propulsion Laboratory (JPL) global TEC maps and data from Doppler phase goniometric complex “Spectr” were analysed. Data for 2009-2011 were investigated. Coherent oscillations with periods of 29-32 and 4 days were detected in atmospheric pressure and Doppler frequency shift variations.

  12. Atmospheric-pressure-plasma nitriding of titanium alloy

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  13. Triploidy induction in Nile tilapia, Oreochromis niloticus L. using pressure, heat and cold shocks

    Microsoft Academic Search

    M. G. Hussain; A. Chatterji; B. J. McAndrew; R. Johnstone

    1991-01-01

    The results of a study aimed at the identification of treatment optima for triploidy induction in recently fertilised Oreochromis niloticus L. eggs by altering the intensity, duration and timing of application of pressure, heat and cold shocks are reported. Preliminary, but not directly comparable, trials suggested the following treatments to be close to the individual agent optima. Pressure: 8,000 psi

  14. Virucidal effect of cold atmospheric gaseous plasma on feline calicivirus, a surrogate for human norovirus.

    PubMed

    Aboubakr, Hamada A; Williams, Paul; Gangal, Urvashi; Youssef, Mohammed M; El-Sohaimy, Sobhy A A; Bruggeman, Peter J; Goyal, Sagar M

    2015-06-01

    Minimal food-processing methods are not effective against foodborne viruses, such as human norovirus (NV). It is important, therefore, to explore novel nonthermal technologies for decontamination of foods eaten fresh, minimally processed and ready-to-eat foods, and food contact surfaces. We studied the in vitro virucidal activity of cold atmospheric gaseous plasma (CGP) against feline calicivirus (FCV), a surrogate of NV. Factors affecting the virucidal activity of CGP (a so-called radio frequency atmospheric pressure plasma jet) were the plasma generation power, the exposure time and distance, the plasma feed gas mixture, and the virus suspension medium. Exposure to 2.5-W argon (Ar) plasma caused a 5.55 log10 unit reduction in the FCV titer within 120 s. The reduction in the virus titer increased with increasing exposure time and decreasing exposure distance. Of the four plasma gas mixtures studied (Ar, Ar plus 1% O2, Ar plus 1% dry air, and Ar plus 0.27% water), Ar plus 1% O2 plasma treatment had the highest virucidal effect: more than 6.0 log10 units of the virus after 15 s of exposure. The lowest virus reduction was observed with Ar plus 0.27% water plasma treatment (5 log10 unit reduction after 120 s). The highest reduction in titer was observed when the virus was suspended in distilled water. Changes in temperature and pH and formation of H2O2 were not responsible for the virucidal effect of plasma. The oxidation of viral capsid proteins by plasma-produced reactive oxygen and nitrogen species in the solution was thought to be responsible for the virucidal effect. In conclusion, CGP exhibits virucidal activity in vitro and has the potential to combat viral contamination in foods and on food preparation surfaces. PMID:25795667

  15. Investigations of the ignition of arc spots on cold cathodes in a noble gas atmosphere

    Microsoft Academic Search

    Jochen Schein; Michael Schumann; D. Nandelstadt; J. Mentel

    1997-01-01

    To investigate the ignition of arc spots on cold cathodes under defined conditions, a special experimental setup was developed. An arc ignited between horn electrodes in a pure argon gas atmosphere is blown magnetically against a third so called commutation electrode, which is negatively biased against the arc plasma. The ignition of arc spots on this cathode was investigated by

  16. Atmospheric cold plasma inactivation of Aerobic Microorganisms on blueberries and effects on quality 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...

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

    Microsoft Academic Search

    Eva Stoffels; Yukinori Sakiyama; David B. Graves

    2008-01-01

    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

  18. Designing Extraterrestrial Plant Growth Habitats with Low Pressure Atmospheres

    NASA Technical Reports Server (NTRS)

    Corey, Kenneth A.

    2002-01-01

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

  19. Designing Extraterrestrial Plant Growth Habitats With Low Pressure Atmospheres

    NASA Technical Reports Server (NTRS)

    Corey, Kenneth A.

    2001-01-01

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

  20. Accurate pressure gradient calculations in hydrostatic atmospheric models

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  1. Preparation of nanodiamonds from carbon nanoparticles at atmospheric pressure.

    PubMed

    Kamali, Ali Reza; Fray, Derek J

    2015-04-01

    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

  2. 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...

  3. High-field operation of submicrometer devices at atmospheric pressure

    Microsoft Academic Search

    M. J. Madou; S. R. Morrison

    1991-01-01

    An array of micrometer-sized field emitter tips was used to produce ions in air or other gases at atmospheric pressure using only low voltages. The ions are produced by the dissociation of gaseous acids or bases in the high electric field near the tips. For example, with formic or acetic acid, ions are formed with the tip at about -50

  4. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    Microsoft Academic Search

    Robert F. Hicks; Hans W. Herrmann

    2003-01-01

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction

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

    Microsoft Academic Search

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

    1999-01-01

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

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

    PubMed

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

    2003-01-15

    Ammonia was successfully synthesized by using a new electrochemical reaction with high current efficiency at atmospheric pressure and at lower temperatures than the Haber-Bosch process. In this method, nitride ion (N3-), which is produced by the reduction from nitrogen gas at the cathode, is anodically oxidized and reacts with hydrogen to produce ammonia at the anode. PMID:12517136

  7. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  8. Gravity and Atmospheric Pressure Effects on Crater Formation in Sand

    Microsoft Academic Search

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

    1969-01-01

    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

  9. TOPICAL REVIEW: Non-thermal atmospheric pressure discharges

    Microsoft Academic Search

    A. Fridman; A. Chirokov; A. Gutsol

    2005-01-01

    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

  10. Atmospheric pressure helium afterglow discharge detector for gas chromatography

    DOEpatents

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

    1986-05-06

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

  11. The Water Table As Affected by Atmospheric Pressure

    Microsoft Academic Search

    A. J. Peck

    1960-01-01

    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

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

    Microsoft Academic Search

    H. Wexler; W. A. Hass

    1962-01-01

    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

  13. Electron yield X-ray absorption spectroscopy at atmospheric pressure

    Microsoft Academic Search

    G. Tourillon; E. Dartyge; A. Fontaine; M. Lemonnier; F. Bartol

    1987-01-01

    The electron yield at atmospheric pressure for X-ray absorption spectroscopy is a new technique able to study the very top surface of thick samples in real environments. A combined detector has been designed at LURE which yields EXAFS spectra in transmission, electron and fluorescence modes. A variable probed thickness is obtained, depending on the polarization. With a positively biased collector

  14. Atmospheric pressure and suicide attempts in Helsinki, Finland

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  15. Decomposition of ilmenite by concentrated KOH solution under atmospheric pressure

    Microsoft Academic Search

    Yumin Liu; Tao Qi; Jinglong Chu; Qijie Tong; Yi Zhang

    2006-01-01

    A new process was provided for decomposition of ilmenite by concentrated KOH solution under atmospheric pressure. The significant effects of reaction temperature, KOH concentration, stirring speed, particle size, and alkali-to-ilmenite mass ratios on titanium extraction were studied. The temperature and initial particle size showed significant influence on titanium extraction. The experimental data of the extraction rates under the relevant operating

  16. Atmospheric Pressure Plasma Jet Treatment of Polyethylene Surfaces for

    E-print Network

    Greifswald, Ernst-Moritz-Arndt-Universität

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

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

    PubMed Central

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

    2013-01-01

    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.

  18. Radio jet refraction in galactic atmospheres with static pressure gradients

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

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

    E-print Network

    Zexian, Cao

    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

  1. Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2

    E-print Network

    Kite, Edwin

    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

  2. Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2

    E-print Network

    Kite, Edwin

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

  3. Atmospheric pressure loading parameters from very long baseline interferometry observations

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

  5. Influence of Atmospheric Pressure and Composition on LIBS

    SciTech Connect

    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

    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.

  6. Exploration Spacecraft and Space Suit Internal Atmosphere Pressure and Composition

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  7. Global atmospheric mass, surface pressure, and water vapor variations

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Christy, John R.; Olson, Jerry G.

    1988-01-01

    Variations in the hydrological cycle and the water vapor content of the atmosphere form a vital part of the "greenhouse" feedback mechanism that can substantially enhance perturbations in the atmosphere arising from changes in forcing, such as those associated with increases in the carbon dioxide content of the atmosphere. An analysis is therefore made of the mean annual cycle interannual variability and trends in global-scale water vapor content of the atmosphere for December 1978 through December 1985, using global analyses from the European Centre for Medium Range Weather Forecasts. Since the variations in total atmospheric mass are almost entirely due to water vapor, two entirely independent global measures of the water vapor content can be compared. These are the total surface pressure due to water vapor from humidity analyses and the total surface pressure itself. For the mean annual cycle these show excellent agreement, and the analyses are therefore compatible with the constraint that the total mass of dry air is conserved. However, it appears that both the interannual variability and trends in water vapor are sufficiently small that they are lost in the noise level of the data, A new estimate of the total mass of the atmosphere is 5.1361×1018 kg for the annual mean, corresponding to a mean surface pressure of 984.43 mbar. It ranges from 5.1352×1018 kg in January to 5.1371×1018 kg in July, owing to the annual cycle in global water vapor which has an amplitude of 1.0×1015 kg (0.2 mbar). The total mass of dry air is estimated to be 5.123×1018 kg (or 981.9 mbar). Also presented is the partitioning of the mass for both the total and the water vapor into the contributions from each hemisphere and as a function of latitude. Mean annual surface pressures in the northern and southern hemispheres are found to be 981.92 and 986.93 mbar, respectively. Monthly mean hemispheric fluctuations in surface pressures of ±1 mbar are not uncommon and tend to be reflected by opposite anomalies in the other hemisphere (consistent with conservation of mass), but the residual in the global monthly mean is of the order of 0.1 mbar. Since this is greater than the magnitude of the possible signal in water vapor surface pressure, the available evidence indicates that the analyzed global monthly anomalies are mostly noise.

  8. Global atmospheric mass, surface pressure, and water vapor variations

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Christy, Johan R.; Olson, Jerry G.

    1987-12-01

    Variations in the hydrological cycle and the water vapor content of the atmosphere form a vital part of the "greenhouse" feedback mechanism that can substantially enhance perturbations in the atmosphere arising from changes in forcing, such as those associated with increases in the carbon dioxide content of the atmosphere. An analysis is therefore made of the mean annual cycle, interannual variability and trends in global-scale water vapor content of the atmosphere for December 1978 through December 1985, using global analyses from the European Centre for Medium Range Weather Forecasts. Since the variations in total atmospheric mass are almost entirely due to water vapor, two entirely independent global measures of the water vapor content can be compared. These are the total surface pressure due to water vapor from humidity analyses and the total surface pressure itself. For the mean annual cycle these show excellent agreement, and the analyses are therefore compatible with the constraint that the total mass of dry air is conserved. However, it appears that both the interannual variability and trends in water vapor are sufficiently small that they are lost in the noise level of the data. A new estimate of the total mass of the atmosphere is 5.1361×1018 kg for the annual mean, corresponding to a mean surface pressure of 984.43 mbar. It ranges from 5.1352×1018 kg in January to 5.1371×1018 kg in July, owing to the annual cycle in global water vapor which has an amplitude of 1.0×1015 kg (0.2 mbar). The total mass of dry air is estimated to be 5.123×1018 kg (or 981.9 mbar). Also presented is the partitioning of the mass for both the total and the water vapor into the contributions from each hemisphere and as a function of latitude. Mean annual surface pressures in the northern and southern hemispheres are found to be 981.92 and 986.93 mbar, respectively. Monthly mean hemispheric fluctuations in surface pressures of ±1 mbar are not uncommon and tend to be reflected by opposite anomalies in the other hemisphere (consistent with conservation of mass), but the residual in the global monthly mean is of the order of 0.1 mbar. Since this is greater than the magnitude of the possible signal in water vapor surface pressure, the available evidence indicates that the analyzed global monthly anomalies are mostly noise.

  9. Dynamics behavior of homogeneous dielectric barrier discharge at atmospheric pressure

    SciTech Connect

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

    2009-07-15

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

  10. Optimizing a remote sensing instrument to measure atmospheric surface pressure

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

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

    Microsoft Academic Search

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

    2007-01-01

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

  12. Diagnostic methods used for atmospheric pressure thermal arc plasma

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  13. Thermally induced atmospheric pressure gas discharges using pyroelectric crystals

    NASA Astrophysics Data System (ADS)

    Johnson, Michael J.; Linczer, John; Go, David B.

    2014-12-01

    Using a heated pyroelectric crystal, an atmospheric pressure gas discharge was generated through the input of heat. When put through a change in temperature, the polarization of a pyroelectric can change significantly, creating a substantial electric potential at its surface. When configured with a grounded sharp counter electrode, a large inhomogeneous electric field forms in the interstitial gas to initiate a corona-like discharge. Under constant heating conditions, gaseous ions drifting to the pyroelectric accumulate and screen the electric field, extinguishing the discharge. By thermally cycling the pyroelectric, negative and positive discharges are generated during heating and cooling, respectively, with peak currents on the order of 80 nA. Time-integrated visualization confirmed the generation of both a corona-like discharge and a surface discharge on the pyroelectric. Parametric studies identified that thermal cycling conditions significantly influence discharge formation for this new atmospheric pressure discharge approach.

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

    SciTech Connect

    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

    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.

  15. Evolutionary pressures on planktonic production of atmospheric sulphur

    NASA Astrophysics Data System (ADS)

    Caldeira, Ken

    1989-02-01

    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.

  16. Double streamer phenomena in atmospheric pressure low frequency corona plasma

    SciTech Connect

    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

    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.

  17. Negative ion-atmospheric pressure photoionization-mass spectrometry

    Microsoft Academic Search

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

    2004-01-01

    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

  18. Characterization of a dc atmospheric pressure normal glow discharge

    Microsoft Academic Search

    David Staack; Bakhtier Farouk; Alexander Gutsol; Alexander Fridman

    2005-01-01

    Atmospheric pressure dc glow discharges were generated between a thin cylindrical anode and a flat cathode. Voltage-current characteristics, visualization of the discharge and estimations of the current density indicate that the discharge is operating in the normal glow regime. Emission spectroscopy and gas temperature measurements using the 2nd positive band of N2 indicate that the discharge forms a non-equilibirum plasma.

  19. The study of atmospheric pressure plasma for surface cleaning

    Microsoft Academic Search

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

    2002-01-01

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

  20. Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

    SciTech Connect

    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

    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.

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

    Microsoft Academic Search

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

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Bilde, M.; Zardini, A. A.; Hong, J.; Tschiskale, M.; Emanuelsson, E.

    2014-12-01

    The atmospheric partitioning between gas and condensed phase of organic molecules is poorly understood, and discrepancies exist between predicted and observed concentrations of secondary organic aerosols. A key problem is the lack of information about thermodynamic properties of semi- and low volatile organic molecules. Saturation vapor pressure and the associated temperature dependence (dH) are key parameters for improving predictive atmospheric models. In this work we combine experiments and thermodynamic modeling to investigate these parameters for a series of polyols, so-called sugar alcohols. These polyols are common in the water soluble fraction of atmospheric aerosols. In our experimental system sub-micron particles are generated by nebulization from aqueous solution, and a mono disperse fraction of the aerosol is selected using a differential mobility analyzer. The particles are allowed to evaporate in a laminar flow reactor, and changes in particle size as function of evaporation time are determined using a scanning mobility particle sizer system. In this work saturation vapor pressures of sugar alcohols at several temperatures have been inferred from such measurements using thermodynamic modeling. Results are presented and discussed in context of atmospheric gas to particle partitioning.

  3. Sterilization and decontamination of surfaces using atmospheric pressure plasma discharges

    SciTech Connect

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

    1999-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  6. An Investigation on Powder Injection in the High-Pressure Cold Spray Process

    Microsoft Academic Search

    T. Han; B. A. Gillispie; Z. B. Zhao

    2009-01-01

    High-pressure cold spray process is a relatively new coating process that uses high-velocity powder particles to form coatings. One of the requirements for this process is to inject the particles to be sprayed into a prenozzle chamber where both the particles and the powder feed gas are entrained into the primary gas stream. In this study, we investigated the effects

  7. Beam heat load and pressure rise in a cold vacuum chamber

    Microsoft Academic Search

    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

    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

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

    PubMed

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

    2014-10-01

    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

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

    E-print Network

    Vertes, Akos

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

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

    E-print Network

    Vertes, Akos

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

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

    E-print Network

    Boyer, Edmond

    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

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

    E-print Network

    Raja, Laxminarayan L.

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

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

    E-print Network

    Raja, Laxminarayan L.

    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

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

    E-print Network

    Vertes, Akos

    Video Article Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure Bindesh., Vertes A. (2010). Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure. JoVE. 43 electrospray ionization (LAESI) and atmospheric pressure infrared matrix-assisted laser desorption ionization

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

    E-print Network

    Vertes, Akos

    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

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

    E-print Network

    Chen, David D.Y.

    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

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

    E-print Network

    Vertes, Akos

    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

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

    E-print Network

    Economou, Demetre J.

    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

  19. Comparative Fourier Transform Infrared Spectroscopy Study of Cold, Pressure, and Heat-Induced Unfolding and Aggregation of Myoglobin

    Microsoft Academic Search

    Filip Meersman; László Smeller; Karel Heremans

    2002-01-01

    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

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

    PubMed

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

    2014-01-28

    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

  1. Time and space variability of spectral estimates of atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Canavero, Flavio G.; Einaudi, Franco

    1987-01-01

    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.

  2. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy; Sweterlisch, Jeffery J.

    2013-01-01

    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.

  3. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy; Sweterlitsch, Jeffrey

    2011-01-01

    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.

  4. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy B.; Sweterlitsch, Jeffrey J.

    2013-01-01

    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.

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

    E-print Network

    Vertes, Akos

    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

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  8. Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  9. Development of an Atmospheric Pressure Ionization Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    1998-01-01

    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.

  10. Driven Motion and Instability of an Atmospheric Pressure Arc

    SciTech Connect

    Max Karasik

    1999-12-01

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

  11. Study of a dual frequency atmospheric pressure corona plasma

    SciTech Connect

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

    2010-05-15

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

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Earle, Alissa M.; Binzel, Richard P.

    2014-11-01

    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.

  14. Heat transport of nitrogen in helium atmospheric pressure microplasma

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  15. Electrode erosion in arc discharges at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Hardy, T. L.

    1985-01-01

    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.

  16. Electron kinetics in a microdischarge in nitrogen at atmospheric pressure

    SciTech Connect

    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

    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.

  17. A lidar system for measuring atmospheric pressure and temperature profiles

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  18. Electrical characteristics and formation mechanism of atmospheric pressure plasma jet

    SciTech Connect

    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

    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.

  19. A simplified system of pressure surfaces for atmospheric analysis

    E-print Network

    Shay, Francis Schofield

    1959-01-01

    Surfaces, Set 8 I. Thickness Table 1 J. Thickness Table 2 K. Thickneas Table 3 L. Thickness Table 4 M. Thickness Table 5 N. Thickness Table 6 0. Thickness Table 7 P. Thickness Table 8 35 36 37 38 39 40 41 42 43 44 45 46 48 49 50...: The use of pressure altitude and altimeter cor- 1 f. t*19y. J1 9M~191. 2, N. l, pp. 1-19. 5. National Advisory Committee for AeronauticsB May 1954:. VManual of the ICAO Atmosphere, NACA Technical Note ~3182 . Washington, D. C. 4, 9 t, , W. J. , 1955...

  20. Twin injection-needle plasmas at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Hong, Yong Cheol; Cho, Soon Chon; Uhm, Han Sup

    2007-04-01

    Twin injection-needle plasmas at atmospheric pressure are introduced as low-temperature nonequilibrium plasma source. The plasmas with long plasma columns of about 55cm 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.

  1. Heat loss and tolerance time during cold exposure in heliox atmosphere at 16 ATA.

    PubMed

    Brubakk, A O; Tønjum, S; Holand, B; Peterson, R E; Hamilton, R W; Morild, E; Onarheim, J

    1982-06-01

    Four different types of protective clothing and three different methods of heat conservation protection were evaluated during an exposure to 4 degrees C cold in a heliox atmosphere at 150 msw. The divers using protective systems with little insulation had to quit the test after 1-2 h due to uncontrollable shivering and an extreme feeling of cold, whereas the divers using the heavily insulated clothing were able to stay in the chamber for 8-10 h. However, even with adequate protection against convective heat loss from the skin, respiratory convective heat loss will be high unless inspired gas is heated. This can be adequately done by using a combined heat-exchanger and scrubber where the heat produced by CO2 absorption is used to warm the inspired gas. PMID:7123699

  2. Characteristics of atmospheric Kelvin waves during warm and cold ENSO phases observed with GPS RO

    NASA Astrophysics Data System (ADS)

    Scherllin-Pirscher, Barbara; Ladstädter, Florian; Steiner, Andrea; Kirchengast, Gottfried

    2015-04-01

    Inter-annual variability in the Earth's troposphere at low and middle latitudes is dominated by the El Niño-Southern Oscillation (ENSO) phenomenon. While ENSO emerges from an atmosphere-ocean interaction in the tropical Pacific, it has a significant impact on global weather and climate. Atmospheric wave dynamics plays a crucial role in this context. However, current understanding of this wave dynamics is mostly based on climate model output and reanalysis data. We use observational data from Global Positioning System (GPS) radio occultation (RO) measurements to investigate characteristics of atmospheric Kelvin waves during warm and cold ENSO phases. Due to their high accuracy and vertical resolution, RO data provide reliable and valuable information on wave-induced temperature oscillations with short vertical wavelengths of a few kilometers. After the launch of the six micro-satellites of the Formosat-3/COSMIC mission in April 2006, the number of RO measurements per day increased significantly compared to earlier time periods. With an appropriate binning strategy, the sampling is therefore sufficiently dense from mid-2006 onwards in order to capture the main characteristics of large-scale atmospheric waves. Frequencies and wavelengths of atmospheric Kelvin waves are extracted from space-time spectral analysis for overlapping 60-day time series centered on each month. In this study we focus on the northern hemisphere winter season DJF (December, January, February) using data from DJF 2006/07 to DJF 2011/12. Comparative results are presented for warm ENSO phases, which occurred in DJF 2006/07 and DJF 2009/10, and for cold ENSO phases in DJF 2007/08, DJF 2010/11, and DJF 2011/12.

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    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.

  4. Atmospheric-pressure plasma decontamination/sterilization chamber

    DOEpatents

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

    2001-01-01

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

  5. Inactivation of Escherichia coli using atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  6. Benzene Dissociation in DC Atmospheric Pressure Air Glow Discharges

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  7. Spectroscopic characterisation of an atmospheric pressure glow discharge (APGD)

    NASA Astrophysics Data System (ADS)

    Gomez, S.; Steen, P. G.; Morrow, T.; Graham, W. G.; Herbert, P. A. F.

    2000-10-01

    Recently there has been considerable interest in atmospheric discharges operating in a glow discharge mode i.e. with a spatial and sheath structure similar to that of low pressure glow discharges [1,2,3]. Here spectroscopy has been used to characterise an atmospheric pressure glow discharge (APGD), operating in air but with various other gases flowing through the inter-electrode space and with textile samples ranging from polyester to wool also present in that space. The emission spectra from 250nm to 800nm were dominated by emission from N2 but when textile samples were present OH emission at around 310nm was also observed. Electron temperatures of 0.5 ± 0.1 eV were determined from the relative intensities of Ar emission lines. When nitrogen was the flowing gas the vibrational states exhibited a Maxwellian distribution with a temperature of 2000K. 1. S. Kanazana et al. J.Phys.D., 21, 836 (1988) 2. J.R.Roth, Industrial Plasma Engineering. (IOPP, London ) 1995 3. F. Massine et al. J. Appl. Phys. 83, 3411-3420 (1998)

  8. An Investigation on Powder Injection in the High-Pressure Cold Spray Process

    Microsoft Academic Search

    T. Han; B. A. Gillispie; Z. B. Zhao

    2009-01-01

    High-pressure cold spray process is a relatively new coating process that uses high-velocity powder particles to form coatings.\\u000a One of the requirements for this process is to inject the particles to be sprayed into a prenozzle chamber where both the\\u000a particles and the powder feed gas are entrained into the primary gas stream. In this study, we investigated the effects

  9. Atmospheric oxygenation caused by a change in volcanic degassing pressure.

    PubMed

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

    2011-10-13

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

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

    E-print Network

    Kushner, Mark

    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

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

    E-print Network

    Roy, Subrata

    Radio frequency induced ionized collisional flow model for application at atmospheric pressures include both volume and surface discharges, at pressures of atmospheric level at low speeds to O 10 Torr atmospheric uniform glow discharge1,11 (AUGD) shows tremendous potential in the areas of electro gas dy- namic

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

    E-print Network

    Droegemeier, Kelvin K.

    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

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

    Microsoft Academic Search

    Pierre-Yves Le Traon; Philippe Gauzelin

    1997-01-01

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

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

    E-print Network

    Economou, Demetre J.

    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

  15. Enhancement of Enzymatic Hydrolysis of Lignocellulosic Wastes by Microwave Pretreatment Under Atmospheric Pressure

    Microsoft Academic Search

    P. Intanakul; M. Krairiksh; P. Kitchaiya

    2003-01-01

    A technique to improve enzymatic hydrolysis of lignocellulosic wastes by microwave pretreatment under atmospheric pressure was developed. Ground rice straw or sugar cane bagasse immersed in a glycerine medium with small amounts of water, was treated with 240 W of microwave irradiation for 10 min at atmospheric pressure. A temperature of about 200°C could be reached in this medium without high pressure

  16. Measurement of viscosity of gaseous mixtures at atmospheric pressure

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

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

    PubMed Central

    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

    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

  18. Characterization of HOCl using atmospheric pressure ionization mass spectrometry

    SciTech Connect

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

    1999-10-14

    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.

  19. Advances in optical diagnostics of atmospheric pressure dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Dilecce, G.; Ambrico, P. F.; de Benedictis, S.

    2008-07-01

    Dielectric barrier discharges at atmospheric pressure have recently received a growing interest because of their potentially advantageous use in a number of applicative fields, in both their main classes of "volume" and "surface" geometric arrangements. The possibility of obtaining a uniform, or glow, regime, in contrast to the usual filamentary one, has further enlarged their perspectives for surface treatments applications. From a diagnostic point of view, the high pressure regime adds problems relevant to an enhanced role of collision quenching, vibrational and rotational relaxation, while maintaining most of the demands of a highly non-equilibrium system for a detailed characterization of its degrees of freedom. In addition, filamentary DBDs are intrinsically pulsed systems, in which the electron impact excitation is confined in small space regions and very short time intervals, such that a prominent afterglow phase, both spatial and temporal, is present in the discharge volume, and kinetic processes involving long-lived species, chemi- luminescent reactions, recombinations (aided by the large pressure) can competitively come into play in the excitation of electronic states. We have applied our ensemble of diagnostic methods, based on time resolved emission and laser spectroscopy, to the investigation of elementary kinetics in DBDs. Here we present our last two years results that include: Optical-Optical Double Resonance (OODR)-LIF measurements of N_2(A^3 Sigma_u^+) density, in a volume DBD that is of relevance in the debate upon the mechanisms for establishing the glow regime (Dilecce 2007); OODR-LIF and emission study on a Masuda type surface discharge (Ambrico 2008); measurement of N_2(C^3 Pi_u, v) quenching and vibrational relaxation rate constants and its relevance to nitrogen Second Positive System emission diagnostics at atmospheric pressure (Dilecce 2006, 2007); kinetics of CN(B^2 Sigma^+, v) formation and violet system emission in N_2 - CH_4 discharges. The latter issue shows in addition a correlation between emissions and surface status (i.e. the presence of a deposit) that is a clear monitor of a gas surface interplay.

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

    SciTech Connect

    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

    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.

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

    E-print Network

    Groth, Clinton P. T.

    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, Ömer L. Gülder University of Toronto January 2011 Available online 12 February 2011 Keywords: High pressure combustion Zero-gravity combustion

  2. Radio jet refraction in galactic atmospheres with static pressure gradients

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  3. Spectroscopic imagine of atmospheric-pressure helium ICP discharges

    SciTech Connect

    Montaser, A.; Boyes, A.L.M.; Cai, M.; Hsiech, C.; Zhang, H. [George Washington Univ., Washington, DC (United States). Dept. of Chemistry

    1994-12-31

    Spatially-resolved information from atmospheric-pressure helium inductively coupled plasmas (He ICP) was acquired with a simple, inexpensive optical imaging spectrometer. The system uses a 35-cm focal length Czerny-Turner monochromator/spectrograph and a solid state charge-injection device (CID) or a charge coupled device (CCD), Quantitative image maps of the plasmas were produced with good resolution. For example, when the CID was used, the entire plasma image could be monitored with a spatial resolution of 0.13 and 0.10 mm in the horizontal and vertical directions. The spectral resolution was 4 mn. Lateral distributions of emission intensities were converted, using an Abel inversion routine, to radial distributions. Some unique features of the He ICP, compared to the commonly used Ar ICP, were identified at or around analytical conditions for elemental analysis of gaseous and aqueous samples.

  4. Effect of Neoangiogenesis Using Micro-spot Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Tsutsui, Chihiro; Komachi, Toshifumi; Kishimoto, Takumi; Hirata, Takamichi; Mori, Akira

    2012-10-01

    Using an in vitro model, we investigated the effect of the atmospheric pressure plasma irradiation to NIH3T3 and porcine aortic endothelial cells. In the plasma exposure experiment using cell proliferation was inhibited in proportion to processing time. However, it was found that this inhibitory effect was suppressed by plasma irradiation and cells are rather on an increase trend. And, in comparison with the cell growth curve for the He gas flow group, the curve for the plasma irradiation group was shifted to the left. We investigated expression analysis in the subsequent experiment with focus on factors related to angiogenesis, it was found that the transient overexpression of VEGF are observed in 24 h from the plasma irradiation. This proliferative effect is likely related to several growth factor releases due to plasma-induced reactive ion/radical interaction.

  5. Efficacy of nonthermal atmospheric pressure plasma for tooth bleaching.

    PubMed

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

    2015-01-01

    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

  6. Atmospheric Pressure Plasmas Incident onto Thin Liquid Layers

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Norberg, Seth; Babaeva, Natalia Yu.; Kushner, Mark J.

    2013-09-01

    The interaction of plasmas with liquids has increasing importance in advanced manufacturing and biomedical applications. Sustaining atmospheric pressure plasmas on liquids (as opposed to in liquids) can increase the chemical activity of the liquid by transferring more easily produced reactive species from the gas phase into the liquid. Often the intent is to treat the surface under the liquid layer, as in plasma medicine. The liquid then acts as a filter which modifies the fluxes of reactive species prior to reaching the underlying surface. The liquid in turn influences the plasma by evaporation which produces a saturated layer of, for example, water vapor above the liquid surface, or by the shape of liquid covered wounds and the dielectric properties of the liquid. Direct plasma exposure (e.g., a dielectric barrier discharge) enables intersection of ion and UV/VUV fluxes with the liquid surface whereas many remote plasma jets typically do not. This increases the rate of hydronium (H3O+) production which affects pH. In this paper, results from a computational investigation on the dynamics of atmospheric pressure plasmas intersecting thin water layers having dissolved gases and proteins will be discussed. Examples are taken from DBD and plasma jet exposure of water layers over a tissue-like dielectric, and plasmas sustained in bubbles in water. The mutual interaction of the plasma and liquid will be discussed based on radiation and ion transport into the water, evaporation, and transport and conversion of plasma produced reactivity through the water layer. The interaction of plasmas with liquids has increasing importance in advanced manufacturing and biomedical applications. Sustaining atmospheric pressure plasmas on liquids (as opposed to in liquids) can increase the chemical activity of the liquid by transferring more easily produced reactive species from the gas phase into the liquid. Often the intent is to treat the surface under the liquid layer, as in plasma medicine. The liquid then acts as a filter which modifies the fluxes of reactive species prior to reaching the underlying surface. The liquid in turn influences the plasma by evaporation which produces a saturated layer of, for example, water vapor above the liquid surface, or by the shape of liquid covered wounds and the dielectric properties of the liquid. Direct plasma exposure (e.g., a dielectric barrier discharge) enables intersection of ion and UV/VUV fluxes with the liquid surface whereas many remote plasma jets typically do not. This increases the rate of hydronium (H3O+) production which affects pH. In this paper, results from a computational investigation on the dynamics of atmospheric pressure plasmas intersecting thin water layers having dissolved gases and proteins will be discussed. Examples are taken from DBD and plasma jet exposure of water layers over a tissue-like dielectric, and plasmas sustained in bubbles in water. The mutual interaction of the plasma and liquid will be discussed based on radiation and ion transport into the water, evaporation, and transport and conversion of plasma produced reactivity through the water layer. Work supported by DOE Fusion Energy Science and NSF.

  7. Controlled Microdroplet Transport in an Atmospheric Pressure Microplasma

    E-print Network

    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

    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 < 100 microseconds. The maximum gas temperature, determined from nitrogen spectral lines, was below 400 K and the observed droplet size reduction implies additional factors beyond standard evaporation, including charge and surface chemistry effects. The successful demonstration of controlled microdroplet streams opens up possibilities for gas-phase microreactors and remote delivery of active species for pla...

  8. Phenomena of oscillations in atmospheric pressure direct current glow discharges

    SciTech Connect

    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

    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.

  9. Decomposition of Glycerine by Water Plasmas at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Takayuki, Watanabe; Narengerile

    2013-04-01

    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.

  10. Controlled microdroplet transport in an atmospheric pressure microplasma

    NASA Astrophysics Data System (ADS)

    Maguire, P. D.; Mahony, C. M. O.; Kelsey, C. P.; Bingham, A. J.; Montgomery, E. P.; Bennet, E. D.; Potts, H. E.; Rutherford, D. C. E.; McDowell, D. A.; Diver, D. A.; Mariotti, D.

    2015-06-01

    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 ?m falling to 13 ?m 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 <100 ?s. The maximum gas temperature, determined from nitrogen spectral lines, was below 400 K and the observed droplet size reduction implies additional factors beyond standard evaporation, including charge and surface chemistry effects. The demonstration of controlled microdroplet streams opens up possibilities for gas-phase microreactors and remote delivery of active species for plasma medicine.

  11. Determination of hexabromocyclododecane by flowing atmospheric pressure afterglow mass spectrometry.

    PubMed

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

    2014-10-01

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

  12. Generation of reactive species by an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kelly, S.; Turner, M. M.

    2014-12-01

    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.

  13. Gas-phase Meerwein reaction of epoxides with protonated acetonitrile generated by atmospheric pressure ionizations

    Microsoft Academic Search

    Lianming Wu; David Q. Liu; Alireza S. Kord

    2010-01-01

    Ethylnitrilium ion can be generated by protonation of acetonitrile (when used as the LC-MS mobile phase) under the conditions\\u000a of atmospheric pressure ionizations, including electrospray ionization (ESI) and atmospheric pressure chemical ionization\\u000a (APCI) as well as atmospheric pressure photoionization (APPI). Ethylnitrilium ion ($$CH_3 - C \\\\equiv \\\\mathop N\\\\limits^ + H$$ and its canonical form $$CH_3 - \\\\mathop C\\\\limits^ + =

  14. Parametric Investigations of an Atmospheric pressure Uniform Glow Discharge in helium

    NASA Astrophysics Data System (ADS)

    Ben Gadri, Rami

    1997-11-01

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

  15. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^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.

  16. Adaptation of Pressure Based CFD Solvers for Mesoscale Atmospheric Problems

    NASA Astrophysics Data System (ADS)

    Kristóf, Gergely; Rácz, Norbert; Balogh, Miklós

    2009-04-01

    General purpose Computational Fluid Dynamics (CFD) solvers are frequently used in small-scale urban pollution dispersion simulations without a large extent of ver- tical flow. Vertical flow, however, plays an important role in the formation of local breezes, such as urban heat island induced breezes that have great significance in the ventilation of large cities. The effects of atmospheric stratification, anelasticity and Coriolis force must be taken into account in such simulations. We introduce a general method for adapting pressure based CFD solvers to atmospheric flow simulations in order to take advantage of their high flexibility in geometrical modelling and meshing. Compressibility and thermal stratification effects are taken into account by utilizing a novel system of transformations of the field variables and by adding consequential source terms to the model equations of incompressible flow. Phenomena involving mesoscale to microscale coupled effects can be analyzed without model nesting, applying only local grid refinement of an arbitrary level. Elements of the method are validated against an analytical solution, results of a reference calculation, and a laboratory scale urban heat island circulation experiment. The new approach can be applied with benefits to several areas of application. Inclusion of the moisture transport phenomena and the surface energy balance are important further steps towards the practical application of the method.

  17. Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

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

    PubMed Central

    Meersman, Filip; Smeller, László; Heremans, Karel

    2002-01-01

    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

  19. Effective Buoyancy, Dynamic Pressure, and Deep Convective Triggering by Cold Pools

    NASA Astrophysics Data System (ADS)

    Jeevanjee, N.; Romps, D. M.

    2014-12-01

    While it is well-known from simulations and observations that cold pools play a key role in the triggering of deep convection, the question remains as to whether this forcing is primarily dynamical or thermodynamical in nature. We address this question by decomposing vertical forces into the dynamic pressure force and effective buoyancy of Davies-Jones (2003), and then apply this to cloud-resolving simulations of deep convection. We find that dynamical forces dominate the triggering, give physical explanations for why this should be, and compare to a shallow convection scenario where the force balance may be different. The thermodynamical properties of cold pools also turn out to play a key role, however, in that the lofted air often comes from mature `warm pools' whose gust fronts are anomalously warm and moist, as emphasized by Tompkins (2001).

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

    NASA Astrophysics Data System (ADS)

    Wang, Mian

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

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  3. Flammability Characteristics of Hydrogen and Its Mixtures with Light Hydrocarbons at Atmospheric and Sub-atmospheric Pressures 

    E-print Network

    Le, Thuy Minh Hai

    2013-07-13

    /vapor. This research focuses on the flammability limits of hydrogen and its binary mixtures with light hydrocarbons (methane, ethane, n-butane, and ethylene) at sub-atmospheric pressures. The flammability limits of hydrogen, light hydrocarbons, and binary mixtures...

  4. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    PubMed

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

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI. PMID:25828352

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  6. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    NASA Astrophysics Data System (ADS)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from <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

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

    E-print Network

    Boyer, Edmond

    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

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  9. Can atmospheric pressure and water table fluctuations be neglected in soil vapor extraction?

    Microsoft Academic Search

    Kehua You; Hongbin Zhan

    Solutions to soil vapor extraction (SVE) are indispensable to characterize the unsaturated zone and to optimize SVE. Most of the existing solutions neglect the fluctuations of atmospheric pressure and water table. This study presents a new semi-analytical solution for SVE by considering the atmospheric pressure and water table fluctuations. Comparisons between the new and previous solutions indicate that the water

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

    E-print Network

    Brinton, Roberta Diaz

    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

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

    Microsoft Academic Search

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

    2003-01-01

    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

  12. Ulster MedJ2005; 74 (2) 113-121 Periods of low atmospheric pressure are associated with

    E-print Network

    Ulster MedJ2005; 74 (2) 113-121 Periods of low atmospheric pressure are associated with high period meteorological data including atmospheric pressure and air temperature were recorded daily incidence in relation to the monthly values for atmospheric pressure, pressure change and temperature

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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).

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

    NASA Astrophysics Data System (ADS)

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

    1993-02-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Haberle, Robert M.; Murphy, James R.; Schaeffer, James; Lee, Hilda

    1993-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2004-04-01

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

  17. Water solubility in rhyolitic silicate melts at atmospheric pressure

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    PubMed

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

    2015-01-01

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

  19. Coupling of pressure waves to clouds in the Jovian atmosphere

    NASA Astrophysics Data System (ADS)

    Gaulme, Patrick; Mosser, Benoît

    2004-12-01

    The receipt for a successful study of the Jovian interior structure is given by the association of seismology and precise visible photometry. In this framework, the micro-satellite project Jovis, presented to the French space agency (Mosser et al, these proceedings), is for Jupiter a copy of what the European space mission COROT is for the stars. The Jovian visible flux being dominated by the albedo map, an accurate analysis of the cloud response to a seismic wave is needed. Therefore, we have revisited the propagation of sound waves in the Jovian troposphere, in order to estimate how they affect the clouds layer. We suppose a vertical wave propagating in a plane parallel atmosphere including an ammonia ice cloud layer. First, considering Jupiter as a mirror, we establish the variations of the reflected solar flux due to the smooth distorsions. Second, introducing thermodynamics, we determine the phase transitions induced by the waves in the clouds. These phase changes are linked to the ice particles growth, and limited by kinetics. A Mie model associated to a simple radiation transfer model allows us to estimate the final albedo fluctuations of the cloud perturbed by a seismic wave. We are then able to quantify the albedo response to a pressure wave.

  20. Atmospheric pressure plasma treatment of lipopolysaccharide in a controlled environment

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  1. Formation of plasma dust structures at atmospheric pressure

    SciTech Connect

    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

    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.

  2. Breakdown of atmospheric pressure microgaps at high excitation frequencies

    NASA Astrophysics Data System (ADS)

    Levko, Dmitry; Raja, Laxminarayan L.

    2015-05-01

    Microwave (mw) breakdown of atmospheric pressure microgaps is studied by a one-dimensional Particle-in-Cell Monte Carlo Collisions numerical model. The effect of both field electron emission and secondary electron emission (due to electron impact, ion impact, and primary electron reflection) from surfaces on the breakdown process is considered. For conditions where field emission is the dominant electron emission mechanism from the electrode surfaces, it is found that the breakdown voltage of mw microdischarge coincides with the breakdown voltage of direct-current (dc) microdischarge. When microdischarge properties are controlled by both field and secondary electron emission, breakdown voltage of mw microdischarge exceeds that of dc microdischarge. When microdischarge is controlled only by secondary electron emission, breakdown voltage of mw microdischarge is smaller than that of dc microdischarge. It is shown that if the interelectrode gap exceeds some critical value, mw microdischarge can be ignited only by electrons initially seeded within the gap volume. In addition, the influence of electron reflection and secondary emission due to electron impact is studied.

  3. Atmospheric pressure arc discharge with ablating graphite anode

    NASA Astrophysics Data System (ADS)

    Nemchinsky, V. A.; Raitses, Y.

    2015-06-01

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

  4. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    PubMed Central

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

    2015-01-01

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

  5. Microchip atmospheric pressure chemical ionization source for mass spectrometry.

    PubMed

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

    2004-11-15

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

  6. Spectral Measurements of Low Temperature Plasma Formation at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Laity, George; Fierro, Andrew; Ryberg, David; Hatfield, Lynn; Neuber, Andreas

    2012-10-01

    This paper describes the study of the emission and re-absorption of ultraviolet (UV) and vacuum ultraviolet (VUV) radiation which is produced during the initial phases of plasma formation leading to electric field breakdown at atmospheric pressures. Specifically, there is interest in understanding the photon dynamics during the streamer to spark phase transition of plasma discharges which form less than 200 ns in millimeter-sized air gaps. Fast rise-time photo-multiplier measurements reveal that the earliest VUV emission occurs in the region near the anode, with emission points following streamer positions identified by fast intensified CCD imaging with fast electronic gating (3 ns). Electron densities and dissociation characteristics are estimated by using measurements of the HI Lyman-? (121.5 nm) Stark-broadened line profile as a function of distance from the anode. Successive measurements in pure N2 environments show a distinct two-step transition from radiative contributions of both the N2 second positive system in the UV (300 - 400 nm) and NI atomic structure in the VUV (120 - 180 nm) during the early plasma phase, to primarily VUV emission shortly after the plasma spark has formed. The observed emission dynamics are due to a combination of N2 dissociation into NI and radiation-less quenching of the N2 molecules.

  7. Power modulation in an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kelly, S.; Turner, M. M.

    2014-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Isbary, Georg

    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.

  9. Influence of Gas Flow on Plasma Length in Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Furuichi, Tsubasa; Ogura, Kazuo

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas and foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of bullet is released like as a plume into the atmosphere. The travel length of plasma increases by increasing the gas flow rate in the laminar flow. The tip of plasma jet is disturbed by the turbulent flow which develops due to the decrease of helium gas ratio on the cross-section.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

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

    PubMed

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

    2010-11-01

    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

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

    PubMed Central

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

    2012-01-01

    In the last twenty years new antibacterial agents approved by the U.S. FDA decreased whereas in parallel the resistance situation of multi-resistant bacteria increased. Thus, community and nosocomial acquired infections of resistant bacteria led to a decrease in the efficacy of standard therapy, prolonging treatment time and increasing healthcare costs. Therefore, the aim of this work was to demonstrate the applicability of cold atmospheric plasma for decolonisation of Gram-positive (Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus) and Gram-negative bacteria (E. coli) using an ex vivo pig skin model. Freshly excised skin samples were taken from six month old female pigs (breed: Pietrain). After application of pure bacteria on the surface of the explants these were treated with cold atmospheric plasma for up to 15 min. Two different plasma devices were evaluated. A decolonisation efficacy of 3 log10 steps was achieved already after 6 min of plasma treatment. Longer plasma treatment times achieved a killing rate of 5 log10 steps independently from the applied bacteria strains. Histological evaluations of untreated and treated skin areas upon cold atmospheric plasma treatment within 24 h showed no morphological changes as well as no significant degree of necrosis or apoptosis determined by the TUNEL-assay indicating that the porcine skin is still vital. This study demonstrates for the first time that cold atmospheric plasma is able to very efficiently kill bacteria applied to an intact skin surface using an ex vivo porcine skin model. The results emphasize the potential of cold atmospheric plasma as a new possible treatment option for decolonisation of human skin from bacteria in patients in the future without harming the surrounding tissue. PMID:22558091

  13. Remote sensing of the atmosphere of Mars using infrared pressure modulation and filter radiometry

    NASA Technical Reports Server (NTRS)

    Mccleese, D. J.; Schofield, J. T.; Zurek, R. W.; Martonchik, J. V.; Haskins, R. D.

    1986-01-01

    The study of the atmosphere and climate of Mars will soon be advanced considerably by the Mars Observer mission. This paper describes the atmospheric sounder for this mission and how it will measure key Martian atmospheric parameters using IR gas correlation and filter radiometry. The instrument now under development will provide high-resolution vertical profiles of atmospheric temperature, pressure, water vapor, dust, and clouds using limb sounding techniques as well as nadir observations of surface thermal properties and polar radiative balance.

  14. Relationship Between the Number Density and the Phase Shift in Microwave Interferometry for Atmospheric Pressure Plasmas

    Microsoft Academic Search

    Mounir Laroussi

    1999-01-01

    Diagnosing atmospheric pressure discharges requires more sophisticated techniques than for low pressure plasmas. The plasma number density is a crucial parameter in several applications. Langmuir probe as a number density measuring technique is not applicable at high pressures because the electron mean free path is shorter than the Debye distance. Microwave interferometry appears to be an effective diagnostic technique in

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

    E-print Network

    Droegemeier, Kelvin K.

    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

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

    E-print Network

    Goodman, Wayne

    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

  17. DC normal glow discharges in atmospheric pressure atomic and molecular gases

    Microsoft Academic Search

    David Staack; Bakhtier Farouk; Alexander Gutsol; Alexander Fridman

    2008-01-01

    DC glow discharges were experimentally investigated in atmospheric pressure helium, argon, hydrogen, nitrogen and air. The discharges were characterized by visualization of the discharges and voltage and current measurements for current of up to several milliamperes. Significant differences are seen in the gas temperature; however all the discharges appear to operate as temperature and pressure scaled versions of low pressure

  18. Tailoring non-equilibrium atmospheric pressure plasmas for healthcare technologies

    NASA Astrophysics Data System (ADS)

    Gans, Timo

    2012-10-01

    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.

  19. Abatement of perfluorinated compounds using microwave plasmas at atmospheric pressure

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

  20. Atmospheric pressure dielectric barrier discharges interacting with liquid covered tissue

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Kushner, Mark J.

    2014-04-01

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

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

    SciTech Connect

    Harvey, A. H. [Thermophysical Properties Division National Institute of Standards and Technology, Boulder, Colorado (United States)] [Thermophysical Properties Division National Institute of Standards and Technology, Boulder, Colorado (United States); McLinden, M. O. [Thermophysical Properties Division, National Institute of Standards and Technology, Boulder, Colorado (United States)] [Thermophysical Properties Division, National Institute of Standards and Technology, Boulder, Colorado (United States); Tew, W. L. [Sensor Science Division National Institute of Standards and Technology, Gaithersburg, Maryland (United States)] [Sensor Science Division National Institute of Standards and Technology, Gaithersburg, Maryland (United States)

    2013-09-11

    We present a detailed thermodynamic analysis of the temperature of the ice point as a function of atmospheric pressure. This analysis makes use of accurate international standards for the properties of water and ice, and of available high-accuracy data for the Henry's constants of atmospheric gases in liquid water. The result is an ice point of 273.150 019(5) K at standard atmospheric pressure, with higher ice-point temperatures (varying nearly linearly with pressure) at lower pressures. The effect of varying ambient CO{sub 2} concentration is analyzed and found to be significant in comparison to other uncertainties in the model. The thermodynamic analysis is compared with experimental measurements of the temperature difference between the ice point and the triple point of water performed at elevations ranging from 145 m to 4302 m, with atmospheric pressures from 101 kPa to 60 kPa.

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

    SciTech Connect

    Hopwood, Jeffrey

    2011-05-31

    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.

  3. Plasma Decomposition of Clathrate Hydrates by 2.45 GHz Microwave Irradiation at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    The purpose of this research is to develop a process to use the plasma decomposition of clathrate hydrates to produce fuel gas. An ordinary microwave (MW) oven is used as the source of 2.45 GHz MW radiation under atmospheric-pressure. The plasma decomposition of the hydrates could pave the way for a new utilization of atmospheric pressure plasma. Cyclopentane (CP) hydrate formed at atmospheric pressure was decomposed by plasma in a MW oven generating gas with a content of 65% hydrogen, 12% CO, and 8% CO2. About 7% of the MW input power was consumed to decompose the hydrates.

  4. In-reactor deformation of cold-worked Zr 2.5Nb pressure tubes

    NASA Astrophysics Data System (ADS)

    Holt, R. A.

    2008-01-01

    Over forty years of in-reactor testing and over thirty years of operating experience in power reactors have provided a broad understanding of the in-reactor deformation of cold-worked Zr-2.5Nb pressure tubes, and an extensive data-base upon which to base models for managing the life of existing reactors and for designing new ones. The effects of the major operating variables and many of the metallurgical variables are broadly understood. The deformation is often considered to comprise three components: thermal creep, irradiation growth and irradiation creep. Of the three, irradiation growth is best understood - it is thought to be driven by the diffusional anisotropy difference (DAD). It is still not clear whether the enhancement of creep by irradiation is due to climb-plus-glide (CPG), stress-induced preferred absorption (SIPA) or elasto-diffusion (ED). The least understood area is the transition between thermal creep and irradiation where the fast neutron flux may either suppress or enhance the creep rate. The three components are generally treated as additive in the models, although it is recognized that this is only a crude approximation of reality. There are still significant gaps in our knowledge besides the thermal- to irradiation-creep transition, for example, the effect of Mo which is produced from Nb by transmutation in the thermal neutron flux is not known, and on-going work is required in a number of areas. This paper reviews the current state of knowledge of the in-reactor deformation of cold-worked Zr-2.5Nb pressure tubes, and highlights areas for further research.

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

    E-print Network

    Zare, Richard N.

    1993-01-01

    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

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

    E-print Network

    Harilal, S. S.

    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

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

    E-print Network

    Boyer, Edmond

    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

  8. Early plume expansion in atmospheric pressure midinfrared laser ablation of water-rich targets Zhaoyang Chen and Akos Vertes*

    E-print Network

    Vertes, Akos

    Early plume expansion in atmospheric pressure midinfrared laser ablation of water-rich targets laser pulses at atmospheric pressure. To describe the laser-target interaction and the plume expansion applications 19,23 . For example, atmospheric pressure matrix-assisted laser desorption ionization AP

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

    E-print Network

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

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

    E-print Network

    Boyer, Edmond

    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

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

    E-print Network

    Boyer, Edmond

    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

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

    E-print Network

    2013-01-01

    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

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

    E-print Network

    Wei, Qiuming

    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

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

    PubMed

    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

    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

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

    PubMed Central

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

    2012-01-01

    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

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

    PubMed

    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

    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

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

    PubMed

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

    2013-04-30

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

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

    PubMed

    Fernández, A; Noriega, E; Thompson, A

    2013-02-01

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

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

    PubMed

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

    2013-01-01

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

  20. Atmosphere

    NSDL National Science Digital Library

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

    2003-01-01

    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

  1. Effect of cold adaptation of ?-and ?-adrenergic responses of blood pressure in hindlimb and small intestine in situ and systemic blood pressure in rabbits

    Microsoft Academic Search

    B. N. Manukhin; V. N. Anan’ev; O. V. Anan’eva

    2007-01-01

    Changes in the main parameters of ?-and ?-adrenergic responses, sensitivity to agonists (EC\\u000a 50) and maximum response (P\\u000a m) of hindlimb and small intestinal blood pressure in situ and systemic blood pressure were studied in rabbits adapted to cold\\u000a for 1–30 days (daily exposures to ?10°C for 6 h). The responses to phenylephrine, noradrenaline, adrenaline, clonidine (?-agonists),\\u000a and isopropylnoradrenaline (?-agonist)

  2. Nanosecond time-resolved microscopic spectroscopy for diagnostics of an atmospheric-pressure discharge plasma formed in aqueous solution

    NASA Astrophysics Data System (ADS)

    Banno, Motohiro; Kanno, Kenta; Someya, Yuu; Yui, Hiroharu

    2015-06-01

    Glow discharge plasma formed in solution under atmospheric pressure has been expected to provide reaction fields with characteristic physical and chemical properties owing to the frequent collisions and reactions of reactive particles inside and the rapid quenching of the products by the surrounding cold solutions. In particular, when an aqueous solution is utilized as the surrounding solution, the atmospheric-pressure in-solution glow (ASG) plasma contains hydrogen and hydroxyl radicals showing large activities for reduction and oxidation, respectively. In addition, because the ASG plasma is formed under atmospheric pressure, the collision frequencies between the particles contained in the plasma are higher than those in other plasmas ordinarily formed under low pressure. This feature should result in rapid energy redistribution among particles contained in the plasma. In the present study, time-resolved optical emission spectroscopy with nanosecond time resolution was applied for the diagnostics of the ASG plasma with chemical species selectivity. The time-resolved measurements revealed that the temporal evolutions of the temperatures of blackbody, hydrogen radical, and hydroxyl radical contained in the ASG plasma consist of two stages: initial rise within 0.15 µs (rising stage) and fluctuation around certain values for about 1 µs (fluctuating stage). In the time region corresponding to the rising stage, the electron number density is about ten times larger than the value temporally averaged during the plasma emission. The initial rise should result from frequent collisions between charged particles accelerated by the applied voltage and unexcited particles. In the fluctuating stage, the electron number density strongly correlates with the increase in the radical temperatures. It is concluded that the electron number density, rather than the electron temperature, is a key parameter determining the temperatures of reactive species in the ASG plasma.

  3. Effect of Atmospheric Pressure on Wet Bulb Depression

    NASA Astrophysics Data System (ADS)

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

    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.

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

    E-print Network

    Covey, Curt

    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 ...

  5. 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...

  6. Negative differential resistance in MIM devices from vacuum to atmospheric pressure

    NASA Astrophysics Data System (ADS)

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

    1996-04-01

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

  7. Elevated atmospheric partial pressure of CO2 and plant growth

    Microsoft Academic Search

    Suan-Chin Wong

    1990-01-01

    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.

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

    SciTech Connect

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

    2013-05-15

    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)].

  9. From surface wave to cloud: An atmosphere physical process in improving the too cold tongue bias and precipitation in a climate model

    NASA Astrophysics Data System (ADS)

    Song, Yajuan; Qiao, Fangli; Song, Zhenya

    2015-04-01

    The coupled atmospheric-ocean general circulation models (AOGCMs) without flux correction still show defects in simulating sea surface temperature (SST) and precipitation, with too cold tongue and obvious double-ITCZ biases in the tropical Pacific. We make an effort to improve SST too cold tongue bias and the north-south asymmetry of zonal-averaged precipitation distribution in the Community Climate System Model version3 (CCSM3) by incorporating the non-breaking wave-induced vertical mixing. The oceanic thermocline depth deepens in the central and eastern tropical Pacific under the wave mixing effect. SST warming characterized as a conspicuous maximum in the central and eastern equatorial Pacific contributes to moisture increasing in atmosphere through evaporation process. The non-uniform SST brings out distinct horizontal gradient in air pressure across the tropics, which result in an abnormal wind convergence in the central Pacific. As a result, an enhanced Walker circulation and Hadley cell are driven by wind gradient and more latent heat. The subsidence branch of the Walker circulation in the eastern Pacific suppress the formation of clouds, so that more shortwave radiation is absorbed by the ocean. However, in the central to western Pacific, the updraft of the Walker circulation with abundant water vapor provides favorable conditions for cloud formation in middle and high troposphere. A positive feedback between water vapor and cloud fraction warms the SST by less longwave radiation releasing. The warm anomalies in the central and eastern Pacific restrict the westward expansion of cold tongue. Furthermore, the intensive updraft of Hadley circulation with high humidity increases rainfall in the low-latitudes of the northern hemisphere.

  10. Genetic influences on blood pressure response to the cold pressor test: results from the Heredity and Phenotype Intervention Heart Study

    Microsoft Academic Search

    Marie-Hélène Roy-Gagnon; Matthew R. Weir; John D. Sorkin; Kathleen A. Ryan; Paul A. Sack; Scott Hines; Lawrence F. Bielake; Patricia A. Peysere; Wendy Postf; Braxton D. Mitchell; Alan R. Shuldiner; Julie A. Douglas

    2008-01-01

    Objectives Blood pressure (BP) response to the cold pressor test (CPT) has been found to predict the development of hypertension and cardiovascular disease in prospective studies. The determinants of BP response to the CPT, including the role of genetic factors, however, are largely unknown. Additionally, to our knowledge, no study has examined the genetics of BP recovery from the CPT,

  11. Ionic wind generation by a wire-cylinder-plate corona discharge in air at atmospheric pressure

    E-print Network

    Paris-Sud XI, Université de

    -cylinder-plate electrode configuration is presented to generate ionic wind with a dc corona discharge in air at atmosphericIonic wind generation by a wire-cylinder-plate corona discharge in air at atmospheric pressure control.6 We examine here several configurations using a corona discharge. The principle of the ionic wind

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

    SciTech Connect

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

    2012-09-15

    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 +}.

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

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenji; Hori, Masaru

    2014-08-01

    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.

  14. High-pressure gas quenching in cold chambers for increased cooling capacity

    SciTech Connect

    Segerberg, S.; Troell, E. [Swedish Institute of Production Engineering Research, Moelndal (Sweden)

    1996-12-31

    Gas quenching for the hardening of steel parts is a lower-pollution alternative to quenching in quenchants such as oil or salt. As the surfaces of the cooled parts remain clean after gas quenching, there is no need to wash them after heat treatment, which reduces the consumption of oils and detergents. The fire risk and ventilation requirements of oil quenching are eliminated. In addition, some trials have shown that gas quenching has a positive effect on distortion, representing a saving in finishing work and thus a reduction in costs. Today, gas quenching is used almost solely in vacuum furnaces. Quenching is normally performed in the same chamber as heating, which means that besides quenching the batch, the quenching system must also remove heat from the heating elements and insulation of the furnace. Previous trials performed by IVF have shown that gas quenching with helium of ball bearing and carburizing steels (and other steels) in sizes up to 25 mm at pressures up to 20 bar in a vacuum furnace can achieve quenching rates and hardnesses similar to those achieved by hot quenching oils. This quenching performance is not, however, capable of dealing with larger sizes or lower-alloy steels. At IVF`s request, ALD Vacuum Technologies GmbH has developed a cold high-pressure gas quenching chamber that is independent of the furnace. As a result, there is no need to cool insulation or heating elements. Quenching can be carried out in the chamber at pressures of up to 40 bar for helium or up to 10 bar for nitrogen. The quenching chamber has been supplied to IVF, and has been used for experimental quenching of steel test pieces and components. Temperatures have been recorded by using some Inconel 600 test probes, {phi} 12,5 x 60 mm, with thermocouples in their centers.

  15. Effect of Atmospheric Pressure on Wet Bulb Depression

    Microsoft Academic Search

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

    2008-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

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

  17. Pressure sounding of the middle atmosphere from ATMOS solar occultation measurements of atmospheric CO(2) absorption lines.

    PubMed

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

    1996-06-01

    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(2) lines with temperature-insensitive strengths by measuring the slant-column CO(2) amount and by adjusting the viewing geometry until the calculated column matches the observed column. Tangent pressures are determined with a spectroscopic precision of l%-3%, corresponding to a tangent-point height precision of 70-210 m. The total uncertainty is limited primarily by the quality of the spectra and ranges between 4% and 6% (280-420 m) for spectra with signal-to-noise ratios of 300:1 and between 4% and 10% for spectra with signal-to-noise ratios of 100:1. The retrieval of atmospheric pressure increases the accuracy of the retrieved-gas concentrations by minimizing the effect of systematic errors introduced by climatological pressure data, ephemeris parameters, and the uncertainties in instrumental pointing. PMID:21085429

  18. Differential Effects of Cold Atmospheric Plasma in the Treatment of Malignant Glioma

    PubMed Central

    Siu, Alan; Volotskova, Olga; Cheng, Xiaoqian; Khalsa, Siri S.; Bian, Ka; Murad, Ferid; Keidar, Michael; Sherman, Jonathan H.

    2015-01-01

    Objective Cold atmospheric plasma (CAP) has recently been shown to selectively target cancer cells with minimal effects on normal cells. We systematically assessed the effects of CAP in the treatment of glioblastoma. Methods Three glioma cell lines, normal astrocytes, and endothelial cell lines were treated with CAP. The effects of CAP were then characterized for viability, cytotoxicity/apoptosis, and cell cycle effects. Statistical significance was determined with student's t-test. Results CAP treatment decreases viability of glioma cells in a dose dependent manner, with the ID50 between 90-120 seconds for all glioma cell lines. Treatment with CAP for more than 120 seconds resulted in viability less than 35% at 24-hours posttreatment, with a steady decline to less than 20% at 72-hours. In contrast, the effect of CAP on the viability of NHA and HUVEC was minimal, and importantly not significant at 90 to 120 seconds, with up to 85% of the cells remained viable at 72-hours post-treatment. CAP treatment produces both cytotoxic and apoptotic effects with some variability between cell lines. CAP treatment resulted in a G2/M-phase cell cycle pause in all three cell lines. Conclusions This preliminary study determined a multi-focal effect of CAP on glioma cells in vitro, which was not observed in the non-tumor cell lines. The decreased viability depended on the treatment duration and cell line, but overall was explained by the induction of cytotoxicity, apoptosis, and G2/M pause. Future studies will aim at further characterization with more complex pre-clinical models. PMID:26083405

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

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

    Microsoft Academic Search

    Leonid Petrov; Jean-Paul Boy

    2004-01-01

    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

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

    Microsoft Academic Search

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

    1979-01-01

    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

  2. Elevated atmospheric partial pressure of CO 2 and plant growth

    Microsoft Academic Search

    S. C. Wong

    1979-01-01

    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

  3. Atmospheric pressure and temperature profiling using near IR differential absorption lidar

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

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

    SciTech Connect

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

    2008-12-29

    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.

  5. Thermal and mechanical loading of particle and RF transmission windows exposed to atmospheric pressure

    Microsoft Academic Search

    R. J. Vidmar

    1997-01-01

    Summary form only given. The mechanical design of a transmission window that seals a port between a low-pressure side and an atmospheric-pressure side for the purpose of passing a high-energy particle beam or radio-frequency waves has many forms. Thermal loading due to energy loss from the beam or the waves and mechanical loading due to the pressure differential across the

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

    Microsoft Academic Search

    William E. Clements; Marvin H. Wilkening

    1974-01-01

    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

  7. Kinetics of silicon-germanium deposition by atmospheric-pressure chemical vapor deposition

    Microsoft Academic Search

    T. I. Kamins; D. J. Meyer

    1991-01-01

    The deposition of Si1?xGex alloy layers in an atmospheric-pressure, chemical vapor deposition reactor has been studied by separately examining the silicon and the germanium components of the deposition rate. The overall deposition rate increases approximately linearly with GeH4 partial pressure, but is relatively independent of SiH2Cl2 partial pressure. The silicon component of the deposition rate increases rapidly with increasing temperature

  8. Tide-induced airflow in a two-layered coastal land with atmospheric pressure fluctuations

    NASA Astrophysics Data System (ADS)

    Li, Jian; Zhan, Hongbin; Huang, Guanhua; You, Kehua

    2011-05-01

    Tide-induced airflow is commonly seen in coastal lands and affects ground stability especially with a less permeable pavement on the ground surface. A tide-induced airflow model in a two-layered unsaturated zone consisting of a highly permeable layer underneath a less permeable layer was established by Li and Jiao [Li HL, JJ Jiao. One-dimensional airflow in unsaturated zone induced by periodic water table fluctuation. Water Resour Res 2005;41:W04007. doi:10.1029/2004WR003916] to describe the one-dimensional airflow with constant atmospheric pressure at the ground surface. In this study, we expand the Li and Jiao model by considering the realistic atmospheric pressure fluctuations and the initial condition. A new transient solution to the airflow model is developed for an initial boundary value problem (IBVP). The transient solution can be used not only to calculate the subsurface air pressure at a future time with a known initial condition, but also to evaluate the asymptotic air pressure variations when time becomes long. The amplitude ratio and phase lag of the subsurface air pressure relative to the tide-induced hydraulic head variations inside the unconfined aquifer below the unsaturated zone are investigated. The results reveal that effect on the subsurface pressure due to changes of atmospheric pressure amplitude depends on the configurations of air resistance in the less permeable layer and the air-filled porosity difference in the two layers. The introduction of atmospheric pressure fluctuations into the airflow model leads to insignificant influence on water table level. A field application of the new solution at Hong Kong International Airport in Hong Kong, China is demonstrated. It indicates that the new transient solution can be conveniently used to evaluate the subsurface air pressure with discrete atmospheric pressure data at the ground surface.

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

    NASA Technical Reports Server (NTRS)

    Spanarkel, Robert; Drew, Malcolm C.

    2002-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  11. On non-equilibrium atmospheric pressure plasma jets and plasma bullet

    NASA Astrophysics Data System (ADS)

    Lu, Xinpei

    2012-10-01

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

  12. How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters.

    PubMed

    Leins, Martina; Gaiser, Sandra; Schulz, Andreas; Walker, Matthias; Schumacher, Uwe; Hirth, Thomas

    2015-01-01

    This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators - a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes. PMID:25938699

  13. Ignition during hydrogen release from high pressure into the atmosphere

    NASA Astrophysics Data System (ADS)

    Oleszczak, P.; Wolanski, P.

    2010-12-01

    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.

  14. 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)

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

    2010-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

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

    Microsoft Academic Search

    E. E. Kunhardt

    2000-01-01

    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

  17. The Effect of Atmospheric Pressure on Rocket Thrust -- Part I.

    ERIC Educational Resources Information Center

    Leitner, Alfred

    1982-01-01

    The first of a two-part question asks: Does the total thrust of a rocket depend on the surrounding pressure? The answer to this question is provided, with accompanying diagrams of rockets. The second part of the question (and answer) are provided in v20 n7, p479, Oct 1982 of this journal. (Author/JN)

  18. Pressure sensing of the atmosphere by solar occultation using broadband CO(2) absorption.

    PubMed

    Park, J H; Russell Iii, J M; Drayson, S R

    1979-06-15

    A technique for obtaining pressure at the tangent point in an IR solar occultation experiment is described. By measuring IR absorption in bands of atmospheric CO(2) (e.g., 2.0 microm, 2.7 microm, or 4.3 microm), 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. PMID:20212584

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

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

    E-print Network

    Jeanmonod, N; Casas-Cubillos, J

    2006-01-01

    The superconducting magnets of the Large Hadron Collider (LHC) will be cooled at 1.9 K by distributed cooling loops working with saturated two-phase superfluid helium flowing in 107 m long bayonet heat exchangers [1] located in each magnet cold-mass cell. The temperature of the magnets could be difficult to control because of the large dynamic heat load variations. Therefore, it is foreseen to measure the heat exchangers pressure to feed the regulation loops with the corresponding saturation temperature. The required uncertainty of the sub-atmospheric saturation pressure measurement shall be of the same order of the one associated to the magnet thermometers, in pressure it translates as ±5 Pa at 1.6 kPa. The transducers shall be radiation hard as they will endure, in the worst case, doses up to 10 kGy and 10**15 neutrons·cm**-2 over 10 years. The sensors under evaluation were installed underground in the dump section of the SPS accelerator with a radiation environment close to the one expected for the L...

  1. CO oxidation over Ru(0001) at near-atmospheric pressures: From chemisorbed oxygen to RuO2

    E-print Network

    Goodman, Wayne

    CO oxidation over Ru(0001) at near-atmospheric pressures: From chemisorbed oxygen to RuO2 Feng Gao shown that at UHV and at near-atmospheric pressure conditions, the most reactive surface phase is a CO on Ru(0001) under oxygen-rich reaction conditions at 550 K and high pressures. This phase was also

  2. Structures and characteristics of the windy atmospheric boundary layer in the South China Sea region during cold surges

    NASA Astrophysics Data System (ADS)

    Cheng, Xue-Ling; Huang, Jian; Wu, Lin; Zeng, Qing-Cun

    2015-06-01

    An observational analysis of the structures and characteristics of a windy atmospheric boundary layer during a cold air outbreak in the South China Sea region is reported in this paper. It is found that the main structures and characteristics are the same as during strong wind episodes with cold air outbreaks on land. The high frequency turbulent fluctuations (period <1 min) are nearly random and isotropic with weak coherency, but the gusty wind disturbances (1 minatmospheric boundary layer at sea, compared with that over land, there are some pronounced differences: (1) the average horizontal speed is almost independent of height, and the vertical velocity is positive in the lower marine atmospheric boundary layer; (2) the vertical flux of horizontal momentum is nearly independent of height in the low layer indicating the existence of a constant flux layer, unlike during strong wind over the land surface; (3) the kinetic energy and friction velocity of turbulent fluctuations are larger than those of gusty disturbances; (4) due to the independence of horizontal speed to height, the horizontal speed itself (not its vertical gradient used over the land surface) can be used as the key parameter to parameterize the turbulent and gusty characteristics with high accuracy.

  3. Land-Atmosphere Interactions in Cold Environments (LATICE): The role of Atmosphere - Biosphere - Cryosphere - Hydrosphere interactions in a changing climate

    NASA Astrophysics Data System (ADS)

    Tallaksen, Lena M.; Burkhart, John F.; Stordal, Frode

    2015-04-01

    Climate change is impacting the high latitudes more rapidly and significantly than any other region of the Earth because of feedback processes between the atmosphere and the underlying surface. A warmer climate has already led to thawing of permafrost, reduced snow cover and a longer growing season; changes, which in turn influence the atmospheric circulation and the hydrological cycle. Still, many studies rely on one-way coupling between the atmosphere and the land surface, thereby neglecting important interactions and feedbacks. The observation, understanding and prediction of such processes from local to regional and global scales, represent a major scientific challenge that requires multidisciplinary scientific effort. The successful integration of earth observations (remote and in-situ data) and model development requires a harmonized research effort between earth system scientists, modelers and the developers of technologies and sensors. LATICE, which is recognized as a priority research area by the Faculty of Mathematics and Natural Sciences at the University of Oslo, aims to advance the knowledge base concerning land atmosphere interactions and their role in controlling climate variability and climate change at high northern latitudes. The consortium consists of an interdisciplinary team of experts from the atmospheric and terrestrial (hydrosphere, cryosphere and biosphere) research groups, together with key expertise on earth observations and novel sensor technologies. LATICE addresses critical knowledge gaps in the current climate assessment capacity through: i) Improving parameterizations of processes in earth system models controlling the interactions and feedbacks between the land (snow, ice, permafrost, soil and vegetation) and the atmosphere at high latitudes, including the boreal, alpine and artic zone. ii) Assessing the influence of climate and land cover changes on water and energy fluxes. iii) Integrating remote earth observations with in-situ data and suitable models to allow studies of finer-scale processes governing land-atmosphere interactions. iv) Addressing observational challenges through the development of novel observational products and networks. The poster presents the LATICE concept, its main research areas and activities.

  4. Asteroid entry in Venusian atmosphere: Pressure and density fields effect on crater formation

    NASA Technical Reports Server (NTRS)

    Schmidt, Robert

    1995-01-01

    The objectives are to look at time scales of overpressure compared to cratering and to determine: what are the transient pressure and density due to atmospheric entry; do shock waves evacuate ambient gas; do transient atmospheric disturbances 'settle down' during cratering; can the pressure/density field be approximated as quasi-static; how does disturbance scale with impactor size; and what is the role of atmospheric thickness. The general approach is to perform inexpensive exploratory calculations, perform experiments to validate code and observe crater growth, and to follow up with more realistic coupling calculations. This viewgraph presentation presents progress made with the objective to obtain useful scaling relationships for crater formation when atmospheric effects are important.

  5. Selective cytotoxicity of indirect nonequilibrium atmospheric pressure plasma against ovarian clear-cell carcinoma.

    PubMed

    Utsumi, Fumi; Kajiyama, Hiroaki; Nakamura, Kae; Tanaka, Hiromasa; Hori, Masaru; Kikkawa, Fumitaka

    2014-01-01

    Ovarian clear cell carcinoma (CCC) is a histological type of epithelial ovarian cancer that is less responsive to chemotherapy and associated with a poorer prognosis than serous and endometrioid carcinoma. Non-thermal atmospheric pressure plasma which produces reactive species has recently led to an explosion of research in plasma medicine. Plasma treatment can be applied to cancer treatment to induce apoptosis and tumor growth arrest. Furthermore, recent studies have shown that a medium exposed to plasma also has an anti-proliferative effect against cancer in the absence of direct exposure to plasma. In this study, we confirmed whether this indirect plasma has an anti-tumor effect against CCC, and investigated whether this efficacy is selective for cancer cells. Non-thermal atmospheric pressure plasma induced apoptosis in CCC cells, while human peritoneal mesothelial cells remained viable. Non-thermal atmospheric pressure plasma exhibits selective cytotoxicity against CCC cells which are resistant to chemotherapy. PMID:25184103

  6. Changes in central artery blood pressure and wave reflection during a cold pressor test in young adults

    Microsoft Academic Search

    Darren P. Casey; Randy W. Braith; Gary L. Pierce

    2008-01-01

    The relative contribution of sympathetic nervous system (SNS)-induced increase in peripheral vascular resistance on central\\u000a artery blood pressure (BP) and aortic wave reflection (augmentation index; AIx) is not completely understood. Central BP and\\u000a wave reflection characteristics were measured using radial artery applanation tonometry before, during a 3-min cold pressor\\u000a test (CPT), and 90 and 180-s post-CPT in 15 young, healthy

  7. Comparison of synoptic climatological features of the atmospheric fields in the "wintertime pressure pattern" around the Japan Islands in early winter with those in midwinter

    NASA Astrophysics Data System (ADS)

    Kato, Kuranoshin; Tomooka, Nozomi; Nishimura, Nanako; Haga, Yuichi

    2015-04-01

    In midwinter, the intense cold air outbreak frequently occurs under the so-called "wintertime pressure pattern", resulting in the huge supply of the sensible (SH) and latent (LH) heats from the Japan Sea and the heavy snowfall events in the Japan Sea side of the Japan Islands. On the other hand, the "wintertime pressure pattern" also appears frequently from November to early December (in "early winter"), although the air temperature around the Japan Islands is still rather higher than in midwinter. Kato et al. (EGU2014-3651) examined the atmospheric situations in association with the relatively large precipitation around the Japan Sea side of the Japan Islands in the "wintertime pressure pattern" even in early winter. They reported the extremely huge amount of LH and SH from the Japan Sea as in midwinter at those events, under the outbreak of the very cold Siberia air mass at least in the mature stage of that pattern. However, since the seasonal cycle of the climate system in East Asia shows the many stages with rapid transitions influenced by the Asian monsoon, the 3-dimensional structures and the atmospheric processes in the "wintertime pressure pattern" would be of rather different character between early winter and midwinter. Thus the present study performed synoptic climatological analyses on the above features in early winter by comparing with those in midwinter based on the daily weather maps by JMA, NCEP/NCAR re-analysis data, and so on, for the 1971/72 to 2009/10winter. Statistical analyses for 1971/72 to 2009/10winter revealed that, although the "wintertime pressure pattern" in early winter had rather shorter persistency than that in midwinter, the eastward surface pressure gradient around the Japan Sea area (around 40N) (corresponding to the geostrophic northerly wind component) in that pressure pattern in early winter sometimes attained the equivalent magnitude to that in midwinter. Furthermore, the increase in the appearance frequency of that pressure pattern in midwinter from that in early winter was reflected by the increase in that with the longer persistency. According to the case study for 1983/84 winter, even in the strong "wintertime pressure pattern" situations, the Siberian High began to extend to the southwestern part of the Japan Islands (around 33N) just like a part of the "moving anticyclone" as the baroclinic instability wave along that latitude in early winter. Besides, the zonal extension of the cold area intruding southward in the lower layer at those events was generally narrower than in midwinter. Further comparison of the features in the "wintertime pressure pattern" between early winter and midwinter will be also discussed in the presentation.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

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

    SciTech Connect

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  14. Electrospun microfiber membrane with atmospheric pressure plasma modified surface\\/architecture as potential solar cell\\/biological applications

    Microsoft Academic Search

    Ruey-Shin Juang; Su-Ya Lin; Chun Huang; Hsu-Yi Cheng; Ching-Yuan Tsai

    2011-01-01

    Electrospun-poly(vinylidenefluoride cohexafluoro- propylene) (PVDF-HFP) micro-fiber membrane is modified by cyclonic atmospheric pressure plasma. The gas phase temperature of cyclonic atmospheric pressure plasma state was around 30? to 90?, indicating this plasma can treat electrospun PVDF-HFP membrane without harmful heat damages. The surface properties of cyclonic atmospheric pressure plasma- treated electrospun PVDF-HFP micro-fiber membranes were examined by the static contact angle

  15. Modeling and simulations of DC and RF atmospheric pressure non-thermal micro plasma discharges: Analysis and applications

    Microsoft Academic Search

    Tanvir Iqbal Farouk

    2009-01-01

    Atmospheric pressure non-thermal plasma discharges are attractive for a wide range of applications due to their operational flexibility. Among the different atmospheric pressure non-thermal plasma sources, atmospheric pressure non-thermal micro plasma discharge is a very recent development. However, the micron scale size of these discharges makes it difficult to measure basic plasma characteristics (species density, gas and electron temperature, electric

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    We report on airborne atmospheric pressure measurements using fiber-based laser technology and the oxygen A-band at 765 nm. Remote atmospheric temperature and pressure measurements are needed for NASA's Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission. ASCENDS will measure atmospheric CO2 dry mixing ratios on a global scale. Remote atmospheric pressure measurements are necessary to normalize ASCENDS CO2 measurements. Our work, funded by the ESTO IIP program, uses erbium doped fiber optic amplifiers and non-linear optics technology to tune laser radiation over the Oxygen A-band between 764.5 nm and 765 nm. Surface reflections are fiber-coupled from a receiver telescope to photon counting detectors. Our pulsed, time gated approach resolves ground reflections from cloud returns. This system successfully recorded O2 absorption spectra during two airborne campaigns aboard a NASA DC-8. Airborne data has been analyzed and fitted to HITRAN reference spectra based upon aircraft meteorological data. Our algorithm linearly scales the HITRAN reference until measurement errors are minimized. Atmospheric pressure changes are estimated by comparing the differential optical depth of the optimum scaled HITRAN spectra to the differential optical depth of the nominal HITRAN spectra. On flights over gradually sloping terrain, these results compare favorably with ground-based observations and predictions from computer models. Measurement uncertainty is commensurate with photon counting noise. We plan to reduce measurement uncertainty in future campaigns by improving transmitter pulse energy and increasing wavelength sweep frequency.

  17. The impact of non-tidal atmospheric pressure loading on global reference frames

    NASA Astrophysics Data System (ADS)

    Bloßfeld, Mathis; Roggenbuck, Ole; Seitz, Manuela; Angermann, Detlef; Thaller, Daniela

    2015-04-01

    The most recent realization of the ITRS, the ITRF2014, will account for non-tidal atmospheric loading corrections applied at the normal equation or the parameter (solution) level. In its function as one of the three contributing ITRS Combination Centers, DGFI-TUM investigates the methodology to apply these corrections at the normal equation level. In this paper, the derived procedure is presented in detail and the following four global SLR-only TRF solutions are compared with each other: (1) conventional SLR-only TRF without non-tidal loading corrections, (2) SLR-only TRF corrected for the displacement due to non-tidal atmospheric pressure loading at the observation equation level, (3) SLR-only TRF corrected for the displacement due to non-tidal atmospheric pressure loading at the normal equation level, (4) SLR-only TRF corrected for the displacement and gravitational effect due to non-tidal atmospheric pressure loading at the observation level. The four solutions are compared w.r.t. the time series of epoch-wise estimated station coordinates, the station coordinate offsets at a reference epoch, the velocities, the commonly adjusted EOPs and the formal errors. The results allow to study the impact of the different methodologies to account for the non-tidal atmospheric pressure loading correction on global TRF solutions. Finally, the presented SLR case study is summarized and the obtained findings are interpreted in the framework of the current ITRF2014 computation.

  18. Microwave air plasma source at atmospheric pressure: Experiment and theory

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

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

    SciTech Connect

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

    2014-01-28

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

  3. Atmospheric pressure chemical ionization of explosives using alternating current corona discharge ion source.

    PubMed

    Usmanov, Dilshadbek Tursunbaevich; Chen, Lee Chuin; Yu, Zhan; Yamabe, Shinichi; Sakaki, Shigeyoshi; Hiraoka, Kenzo

    2015-04-01

    Ensuring public safety and security in today's mobile society requires robust detection technologies that are field-deployable and offer ever-improving sensitivity and specificity. Atmospheric pressure ionization is well suited to field-based sampling but pumping requirements to offset high gas loads can restrict an instrument's deployability and detection sensitivity. In the Special Feature, Usmanov and co-workers describe improved detection for nitrogen-containing explosive compounds using Atmospheric Pressure Chemical Ionization with an alternating current corona discharge source. An electromolded capillary yields a more stable ac corona allowing it to be positioned within 1mm from the inlet for detection limits in the tens of pg. PMID:26149117

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

    SciTech Connect

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

    1991-01-01

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

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

    SciTech Connect

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

    1991-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    We present a detailed thermodynamic analysis of the temperature of the ice point as a function of atmospheric pressure. This analysis makes use of accurate international standards for the properties of water and ice, and of available high-accuracy data for the Henry's constants of atmospheric gases in liquid water. The result is an ice point of 273.150 019(5) K at standard atmospheric pressure, with higher ice-point temperatures (varying nearly linearly with pressure) at lower pressures. The effect of varying ambient CO2 concentration is analyzed and found to be significant in comparison to other uncertainties in the model. The thermodynamic analysis is compared with experimental measurements of the temperature difference between the ice point and the triple point of water performed at elevations ranging from 145 m to 4302 m, with atmospheric pressures from 101 kPa to 60 kPa. At the request of the authors and the Proceedings Editor the above article has been replaced with a corrected version. The original PDF file supplied to AIP Publishing contained several equations with incorrect/missing characters resulting from processes used to create the PDF file. The article has been replaced and the equations now display correctly.

  7. Using Dimers to Measure Biosignatures and Atmospheric Pressure for Terrestrial Exoplanets

    E-print Network

    Misra, Amit; Claire, Mark; Crisp, Dave

    2013-01-01

    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 lev...

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  10. Electron density measurements in an atmospheric pressure air plasma by means of infrared heterodyne interferometry

    Microsoft Academic Search

    Frank Leipold; Robert H. Stark; Ahmed El-Habachi; Karl H. Schoenbach

    2000-01-01

    An infrared heterodyne interferometer has been used to measure the spatial distribution of the electron density in direct current, atmospheric pressure discharges in air. Spatial resolution of the electron density in the high-pressure glow discharge with characteristic dimensions on the order of 100 µm required the use of a CO2 laser at a wavelength of 10.6 µm. For this wavelength

  11. A Review of Arcing Phenomena in Vacuum and in the Transition to Atmospheric Pressure Arcs

    Microsoft Academic Search

    C. W. Kimblin

    1982-01-01

    This paper reviews vacuum-arc phenomena, and the effect of low-pressure gaseous ambients on electrode phenomena in the transition to atmospheric pressure arcs. The 5 main areas addressed are cathode-spot phenomena, anode-spot phenomena, the properties of the interelectrode plasma for both diffuse arcs and columnar arcs, the interaction of vacuum arcs with axial and transverse magnetic fields, and finally, the transition

  12. The frequency response of magnetoelastic sensors to stress and atmospheric pressure

    Microsoft Academic Search

    Dimitris Kouzoudis; Craig A. Grimes

    2000-01-01

    Earlier work demonstrated that the characteristic resonant frequency of magnetoelastic thick-film sensors shifts linearly downwards in response to increasing atmospheric pressure. In this paper, the response mechanism is detailed and shown to be a function of both pressure and the way that the sensor is mechanically stressed. Stressing the sensor, in either the elastic or plastic regime, induces out-of-plane vibrations

  13. An atmospheric-pressure plasma brush driven by sub-microsecond voltage pulses

    Microsoft Academic Search

    X Lu; S Wu; Paul K Chu; D Liu; Y Pan

    2011-01-01

    An atmospheric-pressure room-temperature plasma brush, which can deliver uniform surface treatment effects, is reported. The plasma structure, which includes the negative glow, Faraday dark space and positive column, is clearly visible to the naked eye. The width of the Faraday dark space diminishes with decreasing gap distance and this phenomenon is different from that observed from low-pressure glow discharge plasmas.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  15. Electron density measurements in pulsed atmospheric pressure air plasmas by IR heterodyne interferometry

    Microsoft Academic Search

    F. Leipold; R. H. Stark; A. El-Habachi; K. H. Schoenbach

    2000-01-01

    Summary form only given. Microhollow cathode discharges have been shown to serve as plasma cathodes for atmospheric pressure air discharges. The high pressure discharges are operated dc at currents from 10 mA up to 30 mA and at average electric fields of 1.25 kV\\/cm. The electron density in the dc discharge was estimated to be in the range of 1012

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

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

    PubMed

    Garimella, Sandilya; Zhou, Xiaoyu; Ouyang, Zheng

    2013-12-01

    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

  18. Ozone generation using atmospheric pressure glow discharge in air

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

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

    PubMed

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

    2014-02-01

    We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 ?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

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

    Microsoft Academic Search

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

    1999-01-01

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

  1. Characteristics of short dc glow microdischarges in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly

    2013-09-01

    The main reason that high pressure current-carrying plasmas tend to be unstable is various instability (primarily thermal) of the positive column (PC). So a promising approach is to use short (without PC) discharges that have growing voltage-current characteristic (VAC). These discharges are ignited near the minimum of the Paschen breakdown curve Lmin and it usually have a gap pL <10-20 cm Torr when a distinct PC is absent. In this report the most stable microdischarges were burning with a flat cathode and rounded (or thin rod) anode, which located to a distance less than Lmin when the microdischarge ``choose'' their length itself, so that to match the stable work near Lmin by changing their binding on the anode. For simulations we used 2D hybrid model. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region, in which the electric field is distributed no uniformly and plasma is nonlocal. Gas heating plays an important role in shaping the discharge profiles. The main reason that high pressure current-carrying plasmas tend to be unstable is various instability (primarily thermal) of the positive column (PC). So a promising approach is to use short (without PC) discharges that have growing voltage-current characteristic (VAC). These discharges are ignited near the minimum of the Paschen breakdown curve Lmin and it usually have a gap pL <10-20 cm Torr when a distinct PC is absent. In this report the most stable microdischarges were burning with a flat cathode and rounded (or thin rod) anode, which located to a distance less than Lmin when the microdischarge ``choose'' their length itself, so that to match the stable work near Lmin by changing their binding on the anode. For simulations we used 2D hybrid model. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region, in which the electric field is distributed no uniformly and plasma is nonlocal. Gas heating plays an important role in shaping the discharge profiles. Work supported by FZP and SPbSU.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    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.

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

    E-print Network

    Heller, Barbara

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

  4. An Atmospheric Pressure, Fluidized Bed Combustion System Burning High-Chlorine Coals in the Convection Section

    Microsoft Academic Search

    K. Liu; W. Xie; W.-P. Pan; J. T. Riley

    2000-01-01

    The possibility of fireside corrosion in power plant boiler components is always a major concern when the fuels include high-sulfur and high-chlorine coals (or refuse waste). Sulfur and chloride products may play important roles especially in fireside corrosion in atmospheric pressure, fluidized bed combustion (AFBC) systems, caused by the capture of sulfur and chlorine by limestone used as bed material

  5. Ionic wind generation by a wire-cylinder-plate corona discharge in air at atmospheric pressure

    Microsoft Academic Search

    Dorian F. Colas; Antoine Ferret; David Z. Pai; Deanna A. Lacoste; Christophe O. Laux

    2010-01-01

    A wire-cylinder-plate electrode configuration is presented to generate ionic wind with a dc corona discharge in air at atmospheric pressure. The objective of the work is to maximize the power supplied to the flow in order to increase acceleration while avoiding breakdown. Thus, the proposed experimental setup addresses the problem of decoupling the mechanism of ion generation from that of

  6. Electron density mapping of atmospheric pressure glow discharge in air using two-wavelength interferometry

    Microsoft Academic Search

    J. Pons; Wei-Dong Zhu; K. H. Schoenbach; A. Bugayev

    2006-01-01

    Summary form only given. Atmospheric pressure air plasmas are of interest in aeronautic applications, such as electromagnetic wave cross-section reduction. The required electron densities for this application exceed 1011 cm-3 and may vary strongly over small spatial scales. Mapping of the electron density therefore requires diagnostic techniques that provide high spatial resolution. A laser interferometric method had been introduced by

  7. Destruction of simulated chemical warfare agents in non-thermal atmospheric-pressure air plasma

    Microsoft Academic Search

    J. Jarrige; P. Vervisch

    The decontamination of chemical warfare agents (CWA) using an atmospheric pressure dielectric barrier discharge in air was investigated. Stainles s steel samples inoculated with malathion (a surrogate for nerve agent VX) were placed on the ca thode, where they were treated by the chemical active species produced in the streamers. An effect ive decontamination (>99.7 %) was achieved after 10

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

    Microsoft Academic Search

    F. Leipold; N. Schultz-Jensen; Y. Kusano; H. Bindslev; T. Jacobsen

    2011-01-01

    The decontamination of objects (food) in a sealed container by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua, is used for the experiments. Glass slides were inoculated with L. innocua. The slides were placed inside a low density

  9. Application of Electric Discharges at Atmospheric Pressure and Ambient Temperature for Bio-Decontamination

    Microsoft Academic Search

    Morgane Moreau; Nicole Orange; Jean-Louis Brisset

    2005-01-01

    A new method using an electric discharge at atmospheric pressure and quasi ambient temperature of the gliding arc type is tested for bio-decontamination purposes. Preliminary results are reported on model bacteria of limited pathological character. Inactivation of three strains of Erwinia was tested over 8-minute periods. The inactivation plots of Erwinia chrysanthemi (Ech) show that a 6-minute treatment induces a

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

    SciTech Connect

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

    2006-09-25

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

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

    Microsoft Academic Search

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

    2000-01-01

    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

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

    Microsoft Academic Search

    Mounir Laroussi

    2002-01-01

    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, \\

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

    Microsoft Academic Search

    P. Tregoning; T. van Dam

    2005-01-01

    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

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

    Microsoft Academic Search

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

    2005-01-01

    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 \\

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

    Microsoft Academic Search

    Michael Noeske; Jost Degenhardt; Silke Strudthoff; Uwe Lommatzsch

    2004-01-01

    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

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

    Microsoft Academic Search

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

    1999-01-01

    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

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

    Microsoft Academic Search

    B. V. Hamon

    1966-01-01

    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

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

    Microsoft Academic Search

    Tetsuji Oda; Ryuichi Yamashita; Tadashi Takahashi; Senichi Masuda

    1996-01-01

    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

  19. Properties of an aqueous solution of ionic liquid [Emim][Cl] at standard atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Klinov, A. V.; Fedorov, M. V.; Malygin, A. V.; Minibaeva, L. R.

    2014-10-01

    The density, viscosity, electric conductivity, volumetric thermal expansion coefficient, melting point, and refractive index of an aqueous solution of the [Emim][Cl] ionic liquid are measured over wide ranges of temperature and concentrations at standard atmospheric pressure. Analytical dependences of the investigated properties on the concentration and temperature are suggested.

  20. Measurement of anode falls and anode heat transfer in atmospheric pressure high intensity arcs

    Microsoft Academic Search

    N. A. Sanders; E. Pfender

    1984-01-01

    Electric probe measurements have been performed at and close to a plane, water-cooled anode surface in atmospheric pressure, high intensity argon arcs for different arc configurations which in turn, result in two distinctly different anode arc roots (diffuse and constricted). An adjustable fine wire probe penetrating through a small hole in the center of a flat anode allows for potential

  1. One-Dimensional Fluid Simulation of Atmospheric-Pressure Helium DC Glow Discharges

    Microsoft Academic Search

    Akinori Oda; Takashi Kimura

    2009-01-01

    Atmospheric-pressure glow discharges (APGDs) have been widely used for material processing such as etching, deposition and surface modification and biomedical applications because of the material processing without thermal damage, discharge uniformity over the large area, and so on. In order to suitably utilize APGDs for these applications, further understanding of fundamental properties in APGDs is strongly required. In this paper,

  2. Radial Temperature Profile Measurements in a Microwave Plasma at Atmospheric Pressure

    Microsoft Academic Search

    K. M. Green; M. C. Borras; G. J. Flores III; P. P. Woskov; K. Hadidi; P. Thomas

    1998-01-01

    Radial profile measurements of the electronic excitation and rotational temperature are obtained for a Microwave Plasma Continuous Emissions Monitor (MP-CEM). The MP-CEM, employed in monitoring trace metals in furnace exhausts using atomic emission spectroscopy, operates at atmospheric pressure with air as the working gas. An iron solution is introduced into the plasma, and the intensity of the atomic emission spectrum

  3. Atmospheric pressure plasma cleaning of gold flip chip bump for ultrasonic flip chip bonding

    Microsoft Academic Search

    J-M Koo; J-B Lee; Yj Moon; W-C Moon; S-B Jung

    2008-01-01

    In this study, the optimization of gas and processing time of atmospheric pressure plasma cleaning was performed for successful ultrasonic direct bonding of electroplated Au flip chip bump. The plasma cleaning conditions strongly affected bondability of the Au flip chip bumps. The plasma cleaning with Ar gas for 1 s effectively removed contaminants from the surface without the surface oxidation,

  4. Intracavity laser absorption spectroscopy detection of HCO radicals in atmospheric pressure hydrocarbon flames

    NASA Astrophysics Data System (ADS)

    Cheskis, Sergey

    1995-01-01

    Formyl radical, HCO, was monitored for the first time in an atmospheric pressure premixed hydrocarbon flame. Intracavity laser absorption spectroscopy based on quasi-(cw) argon-ion pumped dye laser was used. The sensitivity of the detection is ˜5×1012 cm-3 and can be improved with better flame and laser stabilization.

  5. Chemical filters by non-thermal atmospheric pressure plasmas for reactive fields

    Microsoft Academic Search

    Osamu Sakai; Tadasuke Morita; Yoshihiko Ueda; Noriaki Sano; Kunihide Tachibana

    2011-01-01

    Non-thermal plasmas in electrode configurations are designed in this study and investigated at atmospheric pressure for generation of reactive fields. A combination of insulated wire electrodes and bare metal wire electrodes makes it possible to obtain a filter-like assembly of microplasmas, even in ambient air or in aqueous solutions. Oxidation and reduction fields are obtained by controlling the gas supply

  6. Hydrophobic surface modification of ramie fibers with ethanol pretreatment and atmospheric pressure plasma treatment

    Microsoft Academic Search

    Zhou Zhou; Xingchen Liu; Benting Hu; Jilong Wang; Danwei Xin; Zhengjia Wang; Yiping Qiu

    2011-01-01

    Incompatibility between hydrophilic natural cellulose fibers and hydrophobic thermoplastic polymer matrices leads to poor interfacial bonding in their composites. This study investigates how atmospheric pressure plasma jet (APPJ) treatment with ethanol pretreatment may improve ramie fiber surface properties for better adhesion to polypropylene. After soaking in ethanol for 10min, ramie fibers are treated by helium plasma. For the plasma treated

  7. Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass Spectrometry

    E-print Network

    Vertes, Akos

    -IR) MALDI (3), laser ablation S.S. Rubakhin, J.V. Sweedler (eds.), Mass Spectrometry Imaging, MethodsChapter 9 Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass method for the direct imaging of biological tis- sues by mass spectrometry. By performing ionization

  8. Radial Measurements of Gas Discharge Parameters of Atmospheric Pressure Microplasma

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  9. High-performance simulations for atmospheric pressure plasma reactor

    NASA Astrophysics Data System (ADS)

    Chugunov, Svyatoslav

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

  10. Influence of flowing helium gas on plasma plume formation in atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Konda, Kohmei; Ogura, Kazuo

    2015-05-01

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and a 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. The helium gas flowing out of quartz tube mixes with air, and the flow channel is composed of the regions of flowing helium gas and air. The plasma plume length is equivalent to the reachable distance of flowing helium gas. Although the amount of helium gas on the flow channel increases by increasing the inner diameter of quartz tube at the same gas flow velocity, the plasma plume length peaks at around 8 m/s of gas flow velocity, which is the result that a flow of helium gas is balanced with the amount of gas. The plasma plume is formed at the boundary region where the flow of helium gas is kept to the wall of the air.

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

    SciTech Connect

    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

    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.

  12. Detection of atmospheric pressure loading using very long baseline interferometry measurements

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  13. Analytical and Numerical Study on Irradiate Ignition of Solid Combustibles in Sub-Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Nakamura, Yuji

    The aim of the present study is to understand the basics of spontaneous ignition of irradiated solid combustibles in sub-atmospheric pressure via analytical and numerical approaches. Final goal of this work is to provide the universal description to the recently-observed ignition characters in sub-atmospheric pressure. An irradiated ignition of horizontally-placed, thin cellulose paper in sub-atmospheric pressure is considered here; the sample is heated at the bottom to lead ignition below the surface in gravimetric environment. Two analytical solutions based on classical ignition theories are referred and 3-D numerical simulation is employed for further discussions. Analytical solutions suggest that the observed ignition trend by authors recently is similar to what would be attained in pure diffusion field, not in the stagnation-point flow field which includes the flow-associated heat loss, except near the lowest pressure range to be ignited. According to the 3-D numerical simulation, it is revealed that either pure diffusion or stagnation-point flow field appears depending on the imposed conditions. When longer ignition delay time is expected, an transport process comes to play a role and ignition is close to what would be attained in stagnation-point flow field, rather than the pure diffusion field. Classical ignition theories are useful to understand the insight of ignition processes in low pressure.

  14. Bivariate wavelet-based clustering of sea-level and atmospheric pressure time series

    NASA Astrophysics Data System (ADS)

    Barbosa, Susana; Gouveia, Sonia; Scotto, Manuel; Alonso, Andres

    2015-04-01

    The atmospheric pressure is responsible for a downward force acting on the sea surface which is compensated, to some extent, by corresponding sea-level variations. The static response of the sea surface can be linearly modelled, a decrease (increase) in atmospheric pressure of 1 mb raising (depressing) sea level by 1 cm. However, the dynamic sea surface response to atmospheric pressure loading, associated with ocean dynamics and wind effects, is scale-dependent and difficult to establish. The present study addresses the co-variability of sea-level and pressure time series in the Baltic Sea from the bivariate analysis of tide gauge and reanalysis records. The time series are normalised by the corresponding standard deviation and the wavelet covariance is computed as a measure of the association between sea-level and pressure across scales. A clustering procedure using a dissimilarity matrix based on the wavelet covariance is then implemented. Different classical clustering techniques, including average, single and complete linkage criteria are applied and the group linkage is selected in order to maximise the dendrogram's goodness-of-fit.

  15. Yttrium Behavior in Aqueous Fluid At High Pressures and Temperatures: Implications for Cold Subduction Zones

    NASA Astrophysics Data System (ADS)

    Tanis, E. A.; Simon, A. C.; Tschauner, O. D.; Frank, M. R.; Chow, P.; Xiao, Y.; Hanchar, J. M.

    2010-12-01

    Constraining thermodynamically the mass transfer of the REE and HFSE from subducted oceanic crust and metasediments to the mantle wedge is fundamental towards interpreting trace element processes in subduction zone recycling and the plumbing system of arc volcanoes. Experimental studies of trace element partitioning involving aqueous fluids at P-T appropriate for slab-mantle wedge conditions are complicated by the difficulties in retrieving the fluid. In this study, we used a diamond anvil cell (HDAC) and in situ synchrotron X-ray florescence (SXRF; at the HPCAT 16-IDD undulator beamline at the APS) to quantify the solubility of Y, a proxy for the heavy REEs, in acidic aqueous fluid under the P-T conditions of cold subducting slabs. These data extend those of Schmidt et al. (2007) from 2 to 5 GPa. Gold was used as the pressure standard via in situ XRD. A synthetic xenotime (YPO4) crystal was placed close to the inside edge of the gasket and the remaining chamber volume filled with a 2 M HCl aqueous solution. A monochromatic incident beam focused to a 35x50 micron spot was used. Fluorescence from the sample was collected 10 degrees away from the incident beam in a 170 degree backscattering geometry and measured by using a silicon drift detector. We verified that the sample and HDAC geometry eliminates completely any secondary fluorescence from xenotime in the sample chamber; i.e., only Y fluorescence from the fluid was measured. A five-point Y standard calibration was used. The collected spectra of standards and the xenotime experiments were summed, and normalized to beam flux and time. The Y peak was extracted, and analyzed by fitting the background and peak area. The standard calibration demonstrates a linear relationship between concentration and peak area. These data indicate that equilibrium is achieved in approximately 1 hr. The Y concentration in the fluid at run conditions was determined by comparing the measured Y peak area with the standard calibration; we note that the Y standard concentrations bracket the measured Y peak area in the unknown solutions. The measured concentration of Y in the fluid is 415(40) ppm at 310 C at 5 GPa, consistent with Schmidt et al. (2007) who report 495 ppm Y at 300 C and 0.1 GPa. The measured concentration of Y in our experiments at 5 GPa and 450 C is 210(20) ppm, indicating that the concentration of Y in acidic aqueous fluid at 450 C decreases with increasing pressure. These new data constrain the effect of P and T on the mass transfer of HREE via a slab-(metasediment)-evolved aqueous fluid into the overlying mantle wedge and arc plumbing system; hence, the data have important implications for the relationship between HREE partitioning and slab-evolved fluid as a function of the P and T attending mass flux in subduction zones.

  16. An upper limit on Early Mars atmospheric pressure from small ancient craters

    NASA Astrophysics Data System (ADS)

    Kite, E. S.; Williams, J.; Lucas, A.; Aharonson, O.

    2012-12-01

    Planetary atmospheres brake, ablate, and disrupt small asteroids and comets, filtering out small hypervelocity surface impacts and causing fireballs, airblasts, meteors, and meteorites. Hypervelocity craters <1 km diameter on Earth are typically caused by irons (because stones are more likely to break up), and the smallest hypervelocity craters near sea-level on Earth are ~20 m in diameter. 'Zap pits' as small as 30 microns are known from the airless moon, but the other airy worlds show the effects of progressively thicker atmospheres:- the modern Mars atmosphere is marginally capable of removing >90% of the kinetic energy of >240 kg iron impactors; Titan's paucity of small craters is consistent with a model predicting atmospheric filtering of craters smaller than 6-8km; and on Venus, craters below ~20 km diameter are substantially depleted. Changes in atmospheric CO2 concentration are believed to be the single most important control on Mars climate evolution and habitability. Existing data requires an early epoch of massive atmospheric loss to space; suggests that the present-day rate of escape to space is small; and offers only limited evidence for carbonate formation. Existing evidence has not led to convergence of atmosphere-evolution models, which must balance poorly understood fluxes from volcanic degassing, surface weathering, and escape to space. More direct measurements are required in order to determine the history of CO2 concentrations. Wind erosion and tectonics exposes ancient surfaces on Mars, and the size-frequency distribution of impacts on these surfaces has been previously suggested as a proxy time series of Mars atmospheric thickness. We will present a new upper limit on Early Mars atmospheric pressure using the size-frequency distribution of 20-100m diameter ancient craters in Aeolis Dorsa, validated using HiRISE DTMs, in combination with Monte Carlo simulations of the effect of paleo-atmospheres of varying thickness on the crater flux. These craters are interbedded with river deposits, and so the atmospheric state they record corresponds to an era when Mars was substantially wetter than the present, probably >3.7 Ga. An important caveat is that our technique cannot exclude atmospheric collapse-reinflation cycles on timescales much shorter than the sedimentary basin-filling time, so it sets an upper limit on the density of a thick stable paleoatmosphere. We will discuss our results in relation to previous estimates of ancient atmospheric pressure, and place new constraints on models of Early Mars climate.

  17. The effect of sub-atmospheric pressure on solid oxide fuel cell behavior

    NASA Astrophysics Data System (ADS)

    Pratt, Joseph William

    Fuel cells, and in particular solid oxide fuel cells (SOFC), have the potential to meet the requirements of a next-generation aeronautical power source: low emissions, high efficiency, and fuel flexibility. However, the design of an SOFC system requires a determination of the operating pressure that will be used, and knowledge of how each component in the system is affected by the entire range of possible operating pressures. In aeronautical applications, this range must include operation at the pressure in the atmosphere at the altitude of flight. Thus, to design SOFC systems for most aeronautical applications, the behavior of the SOFC at pressures from 101 kPa (sea level) to 7 kPa (60,000 ft) must be known. Unfortunately, there are no existing data on SOFC operation at these pressures. Furthermore, the theory, at best, may be able to predict SOFC performance at these conditions but it has never been tested, or at worst the theory itself remains largely uncertain. Either way, experimental work is required to accurately determine the effects of sub-atmospheric pressure on SOFC operation. Through experimentation, this work determines the effects of sub-atmospheric pressure on SOFC performance not only through bulk measurements (e.g., current and voltage) but also through careful examination of all the processes occurring in an operating SOFC. The fuel cell is tested in a facility specially designed and constructed for this work. These experiments show that while changes in pressure in the range of 7 kPa to 99 kPa did not affect the ohmic conduction processes, it greatly affects the activation and mass transfer processes. The results show that the observed changes in activation processes conform closely to those predicted by the Butler-Volmer theory. Observed changes in mass transfer process are attributed to a variation in the governing processes themselves as pressure was lowered: from that governed by a degree of convective Darcy flow to that governed primarily by Knudsen flow. This work provides the first published data of an SOFC operating at sub-atmospheric pressures. Designers of aircraft-based SOFC power systems now have the experimental data needed to help determine the ideal design pressure for these systems.

  18. Airborne and ground based lidar measurements of the atmospheric pressure profile

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  19. The effect of salt crust on the thermal conductivity of one sample of fluvial particulate materials under Martian atmospheric pressures

    Microsoft Academic Search

    Marsha A. Presley; Robert A. Craddock; Natalya Zolotova

    2009-01-01

    A line-heat source apparatus was used to measure thermal conductivities of a lightly cemented fluvial sediment (salinity = 1.1 g · kg?1), and the same sample with the cement bonds almost completely disrupted, under low pressure, carbon dioxide atmospheres. The thermal conductivities of the cemented sample were approximately 3× higher, over the range of atmospheric pressures tested, than the thermal

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

    E-print Network

    Katul, Gabriel

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

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

    SciTech Connect

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

    2013-07-15

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

  2. Atmospheric pressure chemical ionization of fluorinated phenols in atmospheric pressure chemical ionization mass spectrometry, tandem mass spectrometry, and ion mobility spectrometry

    Microsoft Academic Search

    G. A. Eiceman; J. F. Bergloff; J. E. Rodriguez; W. Munro; Z. Karpas

    1999-01-01

    Atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) for fluorinated phenols (C6H5?x\\u000a F\\u000a x\\u000a OH where x=0–5) in nitrogen with Cl? as the reagent ion yielded product ions of M·Cl? through ion associations or (M?H)? through proton abstractions. Proton abstraction was controllable by potentials on the orifice and first lens, suggesting\\u000a that some proton abstraction occurs through collision induced dissociation (CID)

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  4. Atmospheric pressure as a natural climate regulator for a terrestrial planet with a biosphere

    PubMed Central

    Li, King-Fai; Pahlevan, Kaveh; Kirschvink, Joseph L.; Yung, Yuk L.

    2009-01-01

    Lovelock and Whitfield suggested in 1982 that, as the luminosity of the Sun increases over its life cycle, biologically enhanced silicate weathering is able to reduce the concentration of atmospheric carbon dioxide (CO2) so that the Earth's surface temperature is maintained within an inhabitable range. As this process continues, however, between 100 and 900 million years (Ma) from now the CO2 concentration will reach levels too low for C3 and C4 photosynthesis, signaling the end of the solar-powered biosphere. Here, we show that atmospheric pressure is another factor that adjusts the global temperature by broadening infrared absorption lines of greenhouse gases. A simple model including the reduction of atmospheric pressure suggests that the life span of the biosphere can be extended at least 2.3 Ga into the future, more than doubling previous estimates. This has important implications for seeking extraterrestrial life in the Universe. Space observations in the infrared region could test the hypothesis that atmospheric pressure regulates the surface temperature on extrasolar planets. PMID:19487662

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  7. Stellar Atmospheres Near an AGN: The Importance of Radiation Pressure from Trapped Lyman-alpha Photons

    E-print Network

    Weihsueh A. Chiu; B. T. Draine

    1998-03-18

    We derive an analytic expression for the intensity of resonance-line radiation ``trapped'' in a semi-infinite medium. Given a source function and destruction probability per scattering, the radiation pressure due to trapped photons can be calculated by numerically integrating over analytic functions. We apply this formalism to a plane-parallel model stellar atmosphere to calculate the radiation pressure due to Lyman-alpha photons produced following absorption of UV and X-rays from an AGN. For low surface gravity stars near the AGN (g~10 cm/sec^2, r~0.25 pc), we find that the pressure due to Lyman-alpha photons becomes an appreciable fraction of that required for hydrostatic support. If the broad emission line emitting gas in AGNs and QSOs consists of stellar outflows, it may be driven, in part, by Lyman-alpha pressure.

  8. Airborne Lidar measurements of the atmospheric pressure profile with tunable Alexandrite lasers

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Milrod, J.; Walden, H.

    1986-01-01

    The first remote measurements of the atmospheric pressure profile made from an airborne platform are described. The measurements utilize a differential absorption lidar and tunable solid state Alexandrite lasers. The pressure measurement technique uses a high resolution oxygen A band where the absorption is highly pressure sensitive due to collision broadening. Absorption troughs and regions of minimum absorption were used between pairs of stongly absorption lines for these measurements. The trough technique allows the measurement to be greatly desensitized to the effects of laser frequency instabilities. The lidar system was set up to measure pressure with the on-line laser tuned to the absorption trough at 13147.3/cm and with the reference laser tuned to a nonabsorbing frequency near 13170.0/cm. The lidar signal returns were sampled with a 200 range gate (30 vertical resoltion) and averaged over 100 shots.

  9. Cold Atmospheric Plasma Treatment Induces Anti-Proliferative Effects in Prostate Cancer Cells by Redox and Apoptotic Signaling Pathways

    PubMed Central

    Weiss, Martin; Gümbel, Denis; Hanschmann, Eva-Maria; Mandelkow, Robert; Gelbrich, Nadine; Zimmermann, Uwe; Walther, Reinhard; Ekkernkamp, Axel; Sckell, Axel; Kramer, Axel; Burchardt, Martin; Lillig, Christopher H.; Stope, Matthias B.

    2015-01-01

    One of the promising possibilities of the clinical application of cold plasma, so-called cold atmospheric plasma (CAP), is its application on malignant cells and cancer tissue using its anti-neoplastic effects, primarily through the delivery of reactive oxygen and nitrogen species (ROS, RNS). In this study, we investigated the impact of CAP on cellular proliferation and consecutive molecular response mechanisms in established prostate cancer (PC) cell lines. PC cells showed a significantly reduced cell growth following CAP treatment as a result of both an immediate increase of intracellular peroxide levels and through the induction of apoptosis indicated by annexin V assay, TUNEL assay, and the evaluation of changes in nuclear morphology. Notably, co-administration of N-acetylcysteine (NAC) completely neutralized CAP effects by NAC uptake and rapid conversion to glutathione (GSH). Vitamin C could not counteract the CAP induced effects on cell growth. In summary, relatively short treatments with CAP of 10 seconds were sufficient to induce a significant inhibition of cancer proliferation, as observed for the first time in urogenital cancer. Therefore, it is important to understand the mode of CAP related cell death and clarify and optimize CAP as cancer therapy. Increased levels of peroxides can alter redox-regulated signaling pathways and can lead to growth arrest and apoptosis. We assume that the general intracellular redox homeostasis, especially the levels of cellular GSH and peroxidases such as peroxiredoxins affect the outcome of the CAP treatment. PMID:26132846

  10. Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

    Microsoft Academic Search

    Wenfeng Du; Wenrui Hu

    2003-01-01

    For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal\\u000a radiation (e.g. for atmosphere of O2?N2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere.\\u000a As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer

  11. The effect of meteorological data on atmospheric pressure loading corrections in VLBI data analysis

    NASA Astrophysics Data System (ADS)

    Balidakis, Kyriakos; Glaser, Susanne; Karbon, Maria; Soja, Benedikt; Nilsson, Tobias; Lu, Cuixian; Anderson, James; Liu, Li; Andres Mora-Diaz, Julian; Raposo-Pulido, Virginia; Xu, Minghui; Heinkelmann, Robert; Schuh, Harald

    2015-04-01

    Earth's crustal deformation is a manifestation of numerous geophysical processes, which entail the atmosphere and ocean general circulation and tidal attraction, climate change, and the hydrological circle. The present study deals with the elastic deformations induced by atmospheric pressure variations. At geodetic sites, APL (Atmospheric Pressure Loading) results in displacements covering a wide range of temporal scales which is undesirable when rigorous geodetic/geophysical analysis is intended. Hence, it is of paramount importance that the APL signal are removed at the observation level in the space geodetic data analysis. In this study, elastic non-tidal components of loading displacements were calculated in the local topocentric frame for all VLBI (Very Long Baseline Interferometry) stations with respect to the center-of-figure of the solid Earth surface and the center-of-mass of the total Earth system. The response of the Earth to the load variation at the surface was computed by convolving Farrell Green's function with the homogenized in situ surface pressure observations (in the time span 1979-2014) after the subtraction of the reference pressure and the S1, S2 and S3 thermal tidal signals. The reference pressure was calculated through a hypsometric adjustment of the absolute pressure level determined from World Meteorological Organization stations in the vicinity of each VLBI observatory. The tidal contribution was calculated following the 2010 International Earth Rotation and Reference Systems Service conventions. Afterwards, this approach was implemented into the VLBI software VieVS@GFZ and the entirety of available VLBI sessions was analyzed. We rationalize our new approach on the basis that the potential error budget is substantially reduced, since several common errors are not applicable in our approach, e.g. those due to the finite resolution of NWM (Numerical Weather Models), the accuracy of the orography model necessary for adjusting the former as well as the inconsistencies between them, and the interpolation scheme which yields the elastic deformations. Differences of the resulting TRF (Terrestrial Reference Frame) determinations and other products derived from VLBI analysis between the approach followed here and the one employing NWM's data for obtaining the input pressure fields, are illustrated. The providers of the atmospheric pressure loading models employed for our comparisons are GSFC/NASA, the University of Luxembourg, the University of Strasbourg, the Technical University of Vienna and GeoForschungsZentrum of Potsdam.

  12. Enhancement in Surface Atmospheric Pressure Variability Associated with a Major Geomagnetic Storm

    E-print Network

    A. M. Selvam; S. Fadnavis; S. U. Athale; M. I. R. Tinmaker

    1998-07-03

    Observational studies indicate that there is a close association between geomagnetic storm and meteorological parameters. Geomagnetic field lines follow closely the isobars of surface pressure . A Physical mechanism linking upper atmospheric geomagnetic storm disturbances with tropospheric weather has been proposed by the author and her group where it is postulated that vertical mixing by turbulent eddy fluctuations results in the net transport upward of positive charges originating from lower levels accompanied simultaneously by downward flow of negative charges from higher levels. The present study reports enhancement of high frequency (pressure during March 1989 in association with major geomagnetic storm (Ap index = 246) on 13 march 1989.

  13. CO Oxidation on Pt-Group Metals from Ultrahigh Vacuum to Near Atmospheric Pressures. 2. Palladium and Platinum

    E-print Network

    Goodman, Wayne

    CO Oxidation on Pt-Group Metals from Ultrahigh Vacuum to Near Atmospheric Pressures. 2. Palladium at steady-state conditions at low (e2 × 10-3 Torr) and high (2-88 Torr) pressures at various reactant compositions. At low pressures the reaction fell into two regimes, one with a CO-dominant surface where the CO2

  14. Mechanisms of Streamer Propagation Affected by Driven Voltage Polarity in a Cold Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Yang, Lanlan

    2015-01-01

    A two-dimensional self-consistent fluid model is used to investigate the effects of DC-voltage polarity in plasma initiation and propagation of helium plasma jet. The simulation results indicate that the difference in initial breakdown for the positive jet and negative jet leads to a difference in the electron density of about 4 orders of magnitude, even with the same initial electric field, which also influences the subsequent propagation. In the propagation process of negative jets, the ionization process exists in a longer gas channel behind the streamer head. In addition, the drift process to the infinite grounded electrode driven by the electric field results in higher energy consumption in the ionization process. However, in the positive jet, the ionization process mainly exists in the streamer head. Therefore, the differences in the initial breakdown and propagation process make the electric field intensity and the ionization weaker in the streamer head of the negative jet, which explains the weaker and shorter appearance of the negative jet compared to the positive jet. Our model can adequately reproduce the experimental results, viz. a bullet-like propagation in the positive jet and a continuous plasma plume in the negative jet. Furthermore, it also indicates that the streamer velocity shows the same variations as the electron drift velocity for both positive and negative jets.

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

    NASA Technical Reports Server (NTRS)

    Likhanskii, Alexandre

    2012-01-01

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

  16. Measurement of atmospheric surface pressure with a satellite-borne laser.

    PubMed

    Singer, S F

    1968-06-01

    A laser system operating in the oxygen A band (near 0.76 mu) can be used to measure surface pressure by determining absorptance inside and outside of the bands. An accuracy of 10 mbar may require thirty pulses, using a 1-m(2) receiver. A systems analysis shows that internal noise is negligible and that background is not serious, even in daylight. As compared with the corresponding method using the sun, the laser method can be used at night, can discriminate cloud vs surface reflections, and may be able to determine altitude, pressure, and temperature at selected points in the atmosphere. An early test in a manned orbiting satellite is proposed. If successful, the method will have important applications to the projected Global Atmospheric Research Program, to cloud studies, and to oceanography. PMID:20068750

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

    NASA Astrophysics Data System (ADS)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

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

  18. Carbon disulfide reagent allows the characterization of nonpolar analytes by atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Owen, Benjamin C; Gao, Jinshan; Borton, David J; Amundson, Lucas M; Archibold, Enada F; Tan, Xiaoli; Azyat, Khalid; Tykwinski, Rik; Gray, Murray; Kenttämaa, Hilkka I

    2011-07-30

    While atmospheric pressure ionization methodologies have revolutionized the mass spectrometric analysis of nonvolatile analytes, limitations native to the chemistry of these methodologies hinder or entirely inhibit the analysis of certain analytes, specifically, many nonpolar compounds. Examination of various analytes, including asphaltene and lignin model compounds as well as saturated hydrocarbons, demonstrates that atmospheric pressure chemical ionization (APCI) using CS(2) as the reagent produces an abundant and stable molecular ion (M(+•)) for all model compounds studied, with the exception of completely saturated aliphatic hydrocarbons and the two amino acids tested, arginine and phenylalanine. This reagent substantially broadens the applicability of mass spectrometry to nonvolatile nonpolar analytes and also facilitates the examination of radical cation chemistry by mass spectrometry. PMID:21698674

  19. Spectroscopic measurement of plasma gas temperature of the atmospheric-pressure microwave induced nitrogen plasma torch

    NASA Astrophysics Data System (ADS)

    Chen, Chuan-Jie; Li, Shou-Zhe

    2015-06-01

    Atmospheric-pressure microwave induced N2 plasma is diagnosed by optical emission spectroscopy with respect to the plasma gas temperature. The spectroscopic measurement of plasma gas temperature is discussed with respect to the spectral line broadening of Ar I and the various emission rotational–vibrational band systems of N2(B-A), N2(C-B) and \\text{N}2+(\\text{B-X}). It is found that the Boltzmann plot of the selective spectral lines from \\text{N}2+(\\text{B-X}) at 391.4?nm is preferable to others with an accuracy better than 5% for an atmospheric-pressure plasma of high gas temperature. On the basis of the thermal balance equation, the dependences of the plasma gas temperature on the absorbed power, the gas flow rate, and the gas composition are investigated experimentally with photographs recording the plasma morphology.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  1. Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

    SciTech Connect

    Zhang, J.; Wang, Y. H.; Wang, D. Z. [Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-08-15

    Understanding the routes to chaos occurring in atmospheric-pressure dielectric barrier discharge systems by changing controlling parameters is very important to predict and control the dynamical behaviors. In this paper, a route of a quasiperiodic torus to chaos via the strange nonchaotic attractor is observed in an atmospheric-pressure dielectric barrier discharge driven by triangle-wave voltage. By increasing the driving frequency, the discharge system first bifurcates to a quasiperiodic torus from a stable single periodic state, and then torus and phase-locking periodic state appear and disappear alternately. In the meantime, the torus becomes increasingly wrinkling and stretching, and gradually approaches a fractal structure with the nonpositive largest Lyapunov exponent, i.e., a strange nonchaotic attractor. After that, the discharge system enters into chaotic state. If the driving frequency is further increased, another well known route of period-doubling bifurcation to chaos is also observed.

  2. Remote sensing of atmospheric pressure and sea state using laser altimeters

    NASA Technical Reports Server (NTRS)

    Gardner, C. S.

    1985-01-01

    Short-pulse multicolor laser ranging systems are currently being developed for satellite ranging applications. These systems use Q-switched pulsed lasers and streak-tube cameras to provide timing accuracies approaching a few picoseconds. Satellite laser ranging systems have been used to evaluate many important geophysical phenomena such as fault motion, polar motion and solid earth tides, by measuring the orbital perturbations of retroreflector equipped satellites. Some existing operational systems provide range resolution approaching a few millimeters. There is currently considerable interest in adapting these highly accurate systems for use as airborne and satellite based altimeters. Potential applications include the measurement of sea state, ground topography and atmospheric pressure. This paper reviews recent progress in the development of multicolor laser altimeters for use in monitoring sea state and atmospheric pressure.

  3. Atmospheric pressure spatial atomic layer deposition web coating with in situ monitoring of film thickness

    SciTech Connect

    Yersak, Alexander S.; Lee, Yung C. [Department of Mechanical Engineering, University of Colorado at Boulder, 1045 Regent Drive, 422 UCB, Boulder, Colorado 80309-0422 (United States); Spencer, Joseph A.; Groner, Markus D., E-mail: mgroner@aldnanosolutions.com [ALD NanoSolutions, Inc., 580 Burbank Street, Unit 100, Broomfield, Colorado 80020 (United States)

    2014-01-15

    Spectral reflectometry was implemented as a method for in situ thickness monitoring in a spatial atomic layer deposition (ALD) system. Al{sub 2}O{sub 3} films were grown on a moving polymer web substrate at 100?°C using an atmospheric pressure ALD web coating system, with film growth of 0.11–0.13?nm/cycle. The modular coating head design and the in situ monitoring allowed for the characterization and optimization of the trimethylaluminum and water precursor exposures, purge flows, and web speed. A thickness uniformity of ±2% was achieved across the web. ALD cycle times as low as 76?ms were demonstrated with a web speed of 1?m/s and a vertical gap height of 0.5?mm. This atmospheric pressure ALD system with in situ process control demonstrates the feasibility of low-cost, high throughput roll-to-roll ALD.

  4. Cold plasma decontamination of foods.

    PubMed

    Niemira, Brendan A

    2012-01-01

    Cold plasma is a novel nonthermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. This flexible sanitizing method uses electricity and a carrier gas, such as air, oxygen, nitrogen, or helium; antimicrobial chemical agents are not required. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization process. A wide array of cold plasma systems that operate at atmospheric pressures or in low pressure treatment chambers are under development. Reductions of greater than 5 logs can be obtained for pathogens such as Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus. Effective treatment times can range from 120 s to as little as 3 s, depending on the food treated and the processing conditions. Key limitations for cold plasma are the relatively early state of technology development, the variety and complexity of the necessary equipment, and the largely unexplored impacts of cold plasma treatment on the sensory and nutritional qualities of treated foods. Also, the antimicrobial modes of action for various cold plasma systems vary depending on the type of cold plasma generated. Optimization and scale up to commercial treatment levels require a more complete understanding of these chemical processes. Nevertheless, this area of technology shows promise and is the subject of active research to enhance efficacy. PMID:22149075

  5. Using Dimers to Measure Biosignatures and Atmospheric Pressure for Terrestrial Exoplanets

    PubMed Central

    Meadows, Victoria; Claire, Mark; Crisp, Dave

    2014-01-01

    Abstract 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. Key Words: Remote sensing—Extrasolar terrestrial planets—Habitability—Radiative transfer—Biosignatures. Astrobiology 14, 67–86. PMID:24432758

  6. Atmospheric pressure chemical vapor deposition of TiN from tetrakis(dimethylamido)titanium and ammonia

    Microsoft Academic Search

    J. N. Musher; R. G. Gordon

    1996-01-01

    Near stoichiometric titanium nitride (TiN) was deposited from tetrakis(dimethylamido)titanium (TDMAT) and ammonia using atmospheric pressure chemical vapor deposition. Experiments were conducted in a belt furnace; static experiments provided kinetic data and continuous operation uniformly coated 150-mm substrates. Growth rate, stoichiometry, and resistivity are examined as functions of deposition temperature (190420°C), ammonia flow relative to TDMAT (030), and total gas-flow rate

  7. High-temperature open tubular liquid chromatography coupled to atmospheric pressure chemical ionisation mass spectrometry

    Microsoft Academic Search

    Lena M. Nyholm; Per J. R. Sjöberg; Karin E. Markides

    1996-01-01

    A micro heated nebuliser interface was constructed and used for coupling of open tubular liquid chromatography at 150°C to atmospheric pressure chemical ionisation mass spectrometry. For the chromatography, 50 ?m I.D. columns were utilised at a flow-rate of 0.1–1.6 ?l\\/min. The efficiency loss due to the MS detector, including the interface, was found to correspond to only 5% for a

  8. Surface treatment for Cu metallization on polyimide film by atmospheric pressure dielectric barrier discharge plasma system

    Microsoft Academic Search

    Sang-Jin Cho; Shankar Prasad Shrestha; Jin-Hyo Boo

    Atmospheric pressure plasma (APP) surface treatment method was applied to surface modification of polyimide (PI) films to enhance the adhesion between copper layer and PI surface by electroless plating. Also, APP was ignited by radio frequency (RF; 13.56 MHz) plasma power supply. In this study, nontoxic gases (nitrogen, oxygen, and NO (nitrogen:oxygen = 1:1)) plasma effects were mainly investigated instead of toxic gas

  9. Sterilization mechanism for Escherichia coli by plasma flow at atmospheric pressure

    SciTech Connect

    Sato, Takehiko; Miyahara, Takashi; Doi, Akiko; Ochiai, Shiroh; Urayama, Takuya; Nakatani, Tatsuyuki [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan); Graduate School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); ADTEC Plasma Technology Co. Ltd., 5-6-10 Hikino-chou, Fukuyama 721-0942 (Japan); Toyo Advanced Technologies Co., Ltd., 5-3-38 Ujinahigashi, Minami-ku, Hiroshima 734-8501 (Japan)

    2006-08-14

    A mechanism for sterilizing Escherichia coli by a flowing postdischarge and UV radiation of argon plasma at atmospheric pressure was investigated by analyzing the surviving cells and the potassium leakage of cytoplasmic material and by morphological observation. Inactivation of E. coli results from the destruction of the cytoplasmic membrane and the outer membrane under plasma exposure and the destruction of nucleic acids by exposure to ultraviolet radiation from the plasma source.

  10. Ignition of a nanosecond-pulsed near atmospheric pressure discharge in a narrow gap

    Microsoft Academic Search

    Sarah Müller; Dirk Luggenhölscher; Uwe Czarnetzki

    2011-01-01

    The ignition phase and the transition to quasi dc glow operation of a narrow-gap near atmospheric pressure discharge in hydrogen are investigated experimentally. The discharge is ignited by a short 10 ns voltage pulse with a peak voltage of 1.3 kV followed by a 150 ns plateau of about 350 V. Pulsing is at 12 kHz which leaves a significant

  11. Behavior of ZnO-coated alumina dielectric barrier discharge in atmospheric pressure air

    E-print Network

    Li, Meng; Tao, Xiaoping

    2011-01-01

    A complete investigation of the discharge behavior of dielectric barrier discharge device using ZnO-coated dielectric layer in atmospheric pressure is made. Highly conductive ZnO film was deposited on the dielectric surface. Discharge characteristic of the dielectric barrier discharge are examined in different aspects. Experimental result shows that discharge uniformity is improved definitely in the case of ZnO-coated dielectric barrier discharge. And relevant theoretical models and explanation are presented to describing its discharge physics.

  12. Thermoplastic properties of coal at elevated pressures: effects of gas atmospheres

    SciTech Connect

    Khan, M.R.; Jenkins, R.G.

    1985-01-01

    Thermoplastic properties of a Lower Kittanning seam coal have been characterized at a range of gas atmospheres (He, H/sub 2/, N/sub 2/, Ar, and CO/sub 2/). The results suggest that the thermoplastic properties of coal can vary markedly in various gases. At elevated pressures of CO/sub 2/, coals, and porous carbonaceous materials undergo expansion which leads to irreversible structural changes. 11 refs., 5 figs.

  13. Differential absorption lidars for remote sensing of atmospheric pressure and temperature profiles

    NASA Technical Reports Server (NTRS)

    Korb, C. Laurence; Schwemmer, Geary K.; Famiglietti, Joseph; Walden, Harvey; Prasad, Coorg

    1995-01-01

    A near infrared differential absorption lidar technique is developed using atmospheric oxygen as a tracer for high resolution vertical profiles of pressure and temperature with high accuracy. Solid-state tunable lasers and high-resolution spectrum analyzers are developed to carry out ground-based and airborne measurement demonstrations and results of the measurements presented. Numerical error analysis of high-altitude airborne and spaceborne experiments is carried out, and system concepts developed for their implementation.

  14. Dry Reforming of Methane with Carbon Dioxide Using Pulsed DC Arc Plasma at Atmospheric Pressure

    Microsoft Academic Search

    B. H. Yan; Q. Wang; Y. Jin; Y. Cheng

    2010-01-01

    Dry reforming of CH4 with CO2 to produce syngas was investigated in a plasma reactor without catalysts at atmospheric pressure. The reactants passed through\\u000a the plasma zone and reacted in milliseconds with high conversions and selectivity due to the localized high temperature. The\\u000a results showed that both conversions and selectivity were higher when using a DC arc discharge than using

  15. Synthesis of Crystalline Carbon Nitride Thin Films by Pulsed Arc Discharge at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Shi, Changyong; Ma, Zhibin

    2007-08-01

    The preparation of crystalline C3N4 films was investigated using pulsed arc discharge from mixed methanol and ammonia water at atmospheric pressure. The X-ray diffraction (XRD) patterns of the films prepared at a substrate temperature of 450oC suggested that the film was composed of ?-C3N4 and ?-C3N4 crystallites. Raman spectra exhibited distinct peaks which are in good agreement with those predicted theoretically for C3N4 crystallites.

  16. Frequency and voltage dependence of glow and pseudoglow discharges in helium under atmospheric pressure

    Microsoft Academic Search

    Ion Radu; Ray Bartnikas; Michael R. Wertheimer

    2003-01-01

    The pseudoglow and glow discharge behavior of a 0.5-mm metallic-dielectric electrode gap in helium under atmospheric pressure was examined as a function of ac voltage between 0.3 and 32 kHz. The number of discharge current pulses per half-cycle within the pseudoglow was found to diminish with rising frequency, as opposed to the increase observed with rising voltage. The reduction in

  17. Probe measurements in a discharge with liquid nonmetallic electrodes in air at atmospheric pressure

    Microsoft Academic Search

    Yu. A. Barinov; S. M. Shkol’nik

    2002-01-01

    Discharges with liquid nonmetallic electrodes of much interest for applications are investigated. It is found that a dc discharge\\u000a between two streams of tap water in air at atmospheric pressure is stable at a currentof 40?I?100 mA. The discharge exists in the diffuse (volume) form with a relatively low current density (?0.2 A\\/cm2) and a high (above one kilovolt) voltage

  18. Heteroepitaxial growth of ZnO thin films by atmospheric pressure CVD method

    Microsoft Academic Search

    Y. Kashiwaba; F Katahira; K Haga; T Sekiguchi; H Watanabe

    2000-01-01

    High-quality ZnO films were successfully prepared by atmospheric pressure CVD using zinc acetylacetonate (Zn(C5H7O2)2) and oxygen as sources. Epitaxial growth was achieved on (011?2)-oriented single-crystal sapphire substrates. The crystal quality of ZnO films was highly dependent on the film thickness, and crystallinity was improved remarkably at thicknesses over 0.32?m. The cathodoluminescence spectra of the films had a strong peak of

  19. Recent diagonostic results for the steady state - DC atmospheric pressure plasma discharge

    Microsoft Academic Search

    I. Alexeff; E. P. Pradeep; A. Balasundaram

    2006-01-01

    Summary form only given. We have made the following advances for our DC, steady state atmospheric pressure plasma discharge in air. We have measured the free electron concentration in our discharge by converting the 1\\/2 cm. gap, parallel-plate discharge into a parallel-plate transmission line. The frequency used was 6 GHz, corresponding to a free-space wavelength of 15 cm. The path

  20. Ring Opening of Aromatic Polymers by Remote Atmospheric-Pressure Plasma

    Microsoft Academic Search

    Eleazar Gonzalez; Michael D. Barankin; Peter C. Guschl; Robert F. Hicks

    2009-01-01

    An atmospheric-pressure oxygen and helium plasma was used to treat the surfaces of polyetheretherketone, polyphenylsulfone, polyethersulfone, and polysulfone. Water-contact-angle measurements, mechanical pull tests, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy were used to analyze the change in polymer properties. Plasma treatment converted all the materials from a hydrophobic to a hydrophilic state in a few tenths of a second.

  1. Influence of strong electric field on MDA and SOD of rice under atmosphere pressure

    NASA Astrophysics Data System (ADS)

    Xiong, Jianping; Hu, Shengyong; Li, Jikai; He, Songqing; Feng, Lixin

    2013-03-01

    The content of MDA is measured by TBA method in the experiment. The results show that the MDA content of rice seedlings after being radiated in a strong electric field under atmosphere pressure decreases compared to that of those not being radiated while the SOD activity decreases. It indicates that radiated seeds' resistance against oxidative stress can be greatly enhanced. The mechanism and relation between them are analyzed in this paper.

  2. Atmospheric pressure glow discharge desorption mass spectrometry for rapid screening of pesticides in food

    Microsoft Academic Search

    Matthias Conradin Jecklin; Gerardo Gamez; David Touboul; Renato Zenobi

    2008-01-01

    Flowing afterglow atmospheric pressure glow discharge tandem mass spectrometry (APGD-MS\\/MS) is used for the analysis of trace amounts of pesticides in fruit juices and on fruit peel. The APGD source was rebuilt after Andradeet al. (Andradeetal.,Anal.Chem. 2008; 80: 2646-2653; 2654-2663) and mounted onto a hybrid quadrupole time-of-flight mass spectrometer. Apple, cranberry, grape and orange juices as well as fruit peel

  3. Atomic Oxygen Cleaning Shown to Remove Organic Contaminants at Atmospheric Pressure

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.

    1998-01-01

    The NASA Lewis Research Center has developed and filed for a patent on a method to produce atomic oxygen at atmospheric pressure by using a direct current arc in a gas flow mixture of oxygen and helium. A prototype device has been tested for its ability to remove various soot residues from surfaces exposed to fire, and various varnishes such as acrylic and egg white.

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

    NASA Astrophysics Data System (ADS)

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

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

  5. The atmospheric-pressure plasma jet: a review and comparison to other plasma sources

    Microsoft Academic Search

    Andreas Schutze; James Y. Jeong; Steven E. Babayan; Jaeyoung Park; G. S. Selwyn; R. F. Hicks

    1998-01-01

    Atmospheric-pressure plasmas are used in a variety of materials processes. Traditional sources include transferred arcs, plasma torches, corona discharges, and dielectric barrier discharges. In arcs and torches, the electron and neutral temperatures exceed 3000°C and the densities of charge species range from 1016-1019 cm-3. Due to the high gas temperature, these plasmas are used primarily in metallurgy. Corona and dielectric

  6. Spatio-temporally resolved spectroscopic diagnostics of the barrier discharge in air at atmospheric pressure

    Microsoft Academic Search

    K. V. Kozlov; H.-E. Wagner; R. Brandenburg; P. Michel

    2001-01-01

    The technique of spatially resolved cross-correlation spectroscopy (CCS) is used to carry out diagnostic measurements of the barrier discharge (BD) in air at atmospheric pressure. Quantitative estimates for electric field strength E(x,t) and for relative electron density ne(x,t)\\/nemax are derived from the experimentally determined spatio-temporal distributions of the luminosity for the spectral bands of the 0-0 transitions of the second

  7. Dynamics and particle fluxes in atmospheric-pressure electronegative radio frequency microplasmas

    SciTech Connect

    McKay, K.; Iza, F.; Kong, M. G. [School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, LE11-3TU (United Kingdom); Liu, D. X.; Rong, M. Z. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China)

    2011-08-29

    We report on intricate dynamics observed in atmospheric-pressure rf electronegative discharges where electrons and anions are separated due to their different mobilities. This results in the formation of positively charged regions between an electronegative plasma core and an oscillating electron ensemble. It is found that for a given input power, the electron, ion (both positive and negative) and neutral fluxes increase as the gap size is reduced, resulting in a more efficient delivery of chemical species to a treated target.

  8. Modeling of asymmetric pulsed phenomena in dielectric-barrier atmospheric-pressure glow discharges

    SciTech Connect

    Ha Yan [College of Mathematics and Computer Science, Hebei University, Baoding 071002 (China); Wang Huijuan [School of Mathematics and Physics, North China Electric Power University, Baoding 071003 (China); Wang Xiaofei [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2012-01-15

    Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge.

  9. Low frequency Mediterranean sea level variability: The contribution of atmospheric pressure and wind

    Microsoft Academic Search

    Damià Gomis; Simón Ruiz; Marcos G. Sotillo; Enrique Álvarez-Fanjul; Jaume Terradas

    2008-01-01

    We examine 44 yr (1958–2001) of extensively validated model data with the aim of characterizing the contribution of atmospheric pressure and wind to low frequency (the seasonal cycle and lower) Mediterranean sea level variability. The sea level data set was produced within the HIPOCAS Project framework, by means of a long-term barotropic run of the HAMSOM model, with a 1\\/4°×1\\/6° spatial

  10. Modelling of an inductively coupled plasma torch with argon at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Bahouh, Hanene; Rebiai, Saida; Rochette, David; Vacher, Damien; Dudeck, Michel

    2014-05-01

    A fluid dynamic model is used to simulate the electromagnetic field, fluid flow and heat transfer in an inductively coupled plasma torch working at atmospheric pressure for argon plasma. The numerical simulation is carried out by using the finite element method based on COMSOL software. The two-dimensional profiles of the electric field, temperature, velocity and charged particle densities are demonstrated inside the discharge region. These numerical results are obtained for a fixed flow rate, frequency and electric power.

  11. Effect of silicon source gas on silicon-germanium chemical vapor deposition kinetics at atmospheric pressure

    Microsoft Academic Search

    T. I. Kamins; D. J. Meyer

    1992-01-01

    Epitaxial Si1?xGex alloy layers have been deposited in an atmospheric-pressure, chemical-vapor-deposition reactor using dichlorosilane, silane, and disilane, along with germane. The deposition rate increases and the Ge content decreases with increasing reactivity of the silicon-containing gas. The rate increases monotonically with increasing Ge content in the layer for all three gases, in contrast to the behavior seen in systems operating

  12. High sensitivity detection of trace gases at atmospheric pressure using tunable diode lasers

    NASA Technical Reports Server (NTRS)

    Reid, J.; Sinclair, R. L.; Grant, W. B.; Menzies, R. T.

    1985-01-01

    A detailed study of the detection of trace gases at atmospheric pressure using tunable diode lasers is described. The influence of multipass cells, retroreflectors and topographical targets is examined. The minimum detectable infrared absorption ranges from 0.1 percent for a pathlength of 1.2 km to 0.01 percent over short pathlengths. The factors which limit this sensitivity are discussed, and the techniques are illustrated by monitoring atmospehric CO2 and CH4.

  13. Optical response of tin nitride thin films prepared by halide chemical vapor deposition under atmospheric pressure

    Microsoft Academic Search

    N. Takahashi; K. Terada; T. Takahashi; T. Nakamura; W. Inami; Y. Kawata

    2003-01-01

    Optical response of tin nitride (SnNx) films, which were deposited onto quartz substrates by means of atmospheric pressure, halide chemical vapor deposition (AP-HCVD),\\u000a were examined by pulsed irradiation of a YAG laser (532 nm). It was observed that the transmittance of a light of a He-Ne\\u000a laser (633 nm) through the SnNx film decreases after the film is irradiated with

  14. Particle lifting at the soil-air interface by atmospheric pressure excursions in dust devils

    Microsoft Academic Search

    Matthew Balme; Axel Hagermann

    2006-01-01

    Dust devils, small-scale convective vortices found on Earth and on Mars, can transfer substantial quantities of dust from the ground into the atmosphere. It has been proposed that the low-pressure region found at the center of dust devil vortices provides a lift (the `DeltaP' effect) that `sucks up' material from the surface. Two simple models are compared to investigate the

  15. Atmospheric pressure MALDI-FTMS of normal and chemically modified RNA

    Microsoft Academic Search

    Katherine A. Kellersberger; Eizadora T. Yu; Samuel I. Merenbloom; Daniele Fabris

    2005-01-01

    Atmospheric pressure (AP) MALDI has been combined with Fourier transform mass spectrometry (FTMS) to obtain the unambiguous\\u000a characterization of RNA samples modified by solvent accessibility reagents used in structural studies of RNA and protein-RNA\\u000a complexes. The formation of cation adducts typical of MS analysis of nucleic acids was effectively reduced by extensive washing\\u000a of the anionic analytes retained onto the

  16. Application of non-thermal atmospheric pressure ac plasmas to the carbon dioxide reforming of methane

    Microsoft Academic Search

    Stephanie L. Brock; Tomoko Shimojo; Steven L. Suib; Yuji Hayashi; Hiroshige Matsumoto

    2002-01-01

    Methane conversions of 11.9%, yields of hydrogen as high as 23.3% and energy yields of 1.0 mol H2\\/kWh have been achieved from CO2 reforming of CH4 in non-thermal, atmospheric pressure plasma reactors with Pt coated electrodes. Two reactors have been studied. A novel fan type reactor consisting of a movable rotor and immobile stator produced the highest yields in contrast

  17. Electron density and electron temperature in pulsed atmospheric pressure air plasmas

    Microsoft Academic Search

    F. Leipold; K. H. Schoenbach

    2002-01-01

    The use of atmospheric pressure air plasmas as reflectors for microwave radiation with frequencies up to 30 GHz requires electron densities of approximately 1013 cm-3. It has been shown, that direct current microhollow cathode sustained (MCS) discharges meet this requirement. However, the power consumption of such air glow discharges of 5 kW\\/cm3 does not permit scaling to large volumes. Pulsing

  18. Study of an atmospheric pressure glow discharge (APG) for thin film deposition

    Microsoft Academic Search

    Rüdiger Foest; Frank Adler; Florian Sigeneger; Martin Schmidt

    2003-01-01

    We studied a homogeneous atmospheric pressure dielectric barrier discharge in helium with small admixtures (<10?3) of hexamethyldisiloxane (HMDSO) vapor for the deposition of thin silicon organic films on a technical aluminum sheet metal. The powered (100 kHz) plane electrode (80×15 mm2) is covered by a glass insulator layer. Power absorption, sustaining voltage (2 kVpp), gap voltage (700 V), current density

  19. Application of an Air Ionization Device Using an Atmospheric Pressure Corona Discharge Process for Water Purification

    Microsoft Academic Search

    Jens Wohlers; In-Ock Koh; Wolfram Thiemann; Wolfgang Rotard

    2009-01-01

    Pesticides presently being discharged into the aquatic environment are not only toxic but also only partially biodegradable,\\u000a they are not easily removed by conventional water treatment plants. Air ionization devices using an atmospheric pressure corona\\u000a discharge process show great promise in improving degradation of chemical and biological contaminants in water purification\\u000a plants. In order to assess the effectiveness of this

  20. Interaction of a jet with a radiation pressure-dominated atmosphere - The case of SS 433

    NASA Technical Reports Server (NTRS)

    Arav, Nahum; Begelman, Mitchell C.

    1993-01-01

    A phenomenological model for the enigmatic object SS 433 is developed in which SS 433 is a neutron star (NS) surrounded by a dense accreted atmosphere. Jets are created close to the neutron star surface by the rapidly spinning NS, toward which matter flows at a super-Eddington rate. This supercritical accretion leads to a quasi-spherical atmosphere around the NS with very high pressure and density close to the surface. The interaction of the jet with the atmosphere as it propagates through it is discussed in detail. A boundary layer (BL) due to radiation viscosity forms between the jet and the surrounding medium. This BL can be visualized as a cocoon of low-density matter around the jet which prevents mass entrainment into the jet. A study of X-ray spectra shows how the radiation-viscous BL can explain the very small Delta v/v that is observed in the jets.