Sample records for gas plasma sterilization

  1. Gas Plasma Afterglow Sterilization : A New Approach

    Microsoft Academic Search

    S. Moreau; M. Moisan; M. Tabrizian; J. Barbeau; A. Ricard; L'h. Yahia

    1999-01-01

    Gas plasma afterglow offers the possibility of sterilizing heat-sensitive polymer-based medical devices. Focusing on the influence of plasma parameters on sterilization efficacy, we have shown that gas composition, pressure and flow, and power density affect the destruction rate of our reference bacterial spores, Bacillus subtilis var. niger. NO titration method has enabled us distinguishing between two effects : spore coat

  2. Gas plasma sterilization of microorganisms and mechanisms of action

    PubMed Central

    SHINTANI, HIDEHARU; SAKUDO, AKIKAZU; BURKE, PETER; McDONNELL, GERALD

    2010-01-01

    The use of true gas plasmas for the inactivation of microorganisms is an area of dynamic research. Many types of gases are used as a source of plasma, and different plasma production methods have been applied. The antimicrobial mechanisms of oxygen-based gas plasmas may be due to an etching effect on microbial structures, particularly bacterial endospores resulting in shrinkage. By contrast, the definite mechanisms of actions of other gas plasma sources, such as N2, He, Ne, Ar and Xe gases, have not been clearly defined and indeed may be distinct. The speculated mechanisms of these gas plasmas involve the direct attack of metastable (excited molecular), UV and/or VUV to microbial structures, specifically the inner membrane and DNA in the core of bacterial endospores. According to this speculation, sterilized spore figures would remain unchanged. However, these mechanisms remain to be clarified. Future perspectives on the use of gas plasma for sterilization are of interest, as it is possible that appropriate sterility assurance levels can be obtained in parallel with material and functional compatibility. Traditional sterilization methods are often limited in these requirements. Therefore, gas plasma sterilization may prove to be an appropriate alternative sterilization procedure. PMID:22993596

  3. Effects of additional vapors on sterilization of microorganism spores with plasma-excited neutral gas

    NASA Astrophysics Data System (ADS)

    Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

    2015-01-01

    Some fundamental experiments are carried out in order to develop a plasma process that will uniformly sterilize both the space and inner wall of the reactor chamber at atmospheric pressure. Air, oxygen, argon, and nitrogen are each used as the plasma source gas to which mixed vapors of water and ethanol at different ratios are added. The reactor chamber is remotely located from the plasma area and a metal mesh for eliminating charged particles is installed between them. Thus, only reactive neutral particles such as plasma-excited gas molecules and radicals are utilized. As a result, adding vapors to the source gas markedly enhances the sterilization effect. In particular, air with water and/or ethanol vapor and oxygen with ethanol vapor show more than 6-log reduction for Geobacillus stearothermophilus spores.

  4. The application of a non-thermal plasma generated by gas-liquid gliding arc discharge in sterilization

    NASA Astrophysics Data System (ADS)

    Du, Chang Ming; Wang, Jing; Zhang, Lu; Xia Li, Hong; Liu, Hui; Xiong, Ya

    2012-01-01

    Gliding arc discharge has been investigated in recent years as an innovative physicochemical technique for contaminated water treatment at atmospheric pressure and ambient temperature. In this study we tested a gas-liquid gliding arc discharge reactor, the bacterial suspension of which was treated circularly. When the bacterial suspension was passed through the electrodes and circulated at defined flow rates, almost 100% of the bacteria were killed in less than 3.0 min. Experimental results showed that it is possible to achieve an abatement of 7.0 decimal logarithm units within only 30 s. Circulation flow rates and types of feeding gas caused a certain impact on bacteria inactivation, but the influences are not obvious. So, under the promise of sterilization effect, industrial applications can select their appropriate operating conditions. All inactivation curves presented the same three-phase profile showing an apparent sterilization effect. Analysis of the scanning electron microscope images of bacterial cells supports the speculation that the gas-liquid gliding arc discharge plasma is acting under various mechanisms driven essentially by oxidation and the effect of electric field. These results enhance the possibility of applying gas-liquid gliding arc discharge decontamination systems to disinfect bacterial-contaminated water. Furthermore, correlational research indicates the potential applications of this technology in rapid sterilization of medical devices, spacecraft and food.

  5. 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.

  6. Plasma Sterilization: Opportunities and Microbial Assessment Strategies in Medical Device Manufacturing

    Microsoft Academic Search

    Ozlem Yardimci; Peter Setlow

    2010-01-01

    Non-thermal gas discharge plasmas have significant potential as novel sterilization\\/decontamination agents in medical device manufacturing, and such agents may well be accepted by regulatory agencies. A number of aspects of plasma technology are currently under active investigation by many institutions and companies in order to obtain a thorough understanding of plasma sterilization as an alternative to conventional sterilization methods for

  7. Plasma Sterilization: New Epoch in Medical Textiles

    NASA Astrophysics Data System (ADS)

    Senthilkumar, P.; Arun, N.; Vigneswaran, C.

    2015-04-01

    Clothing is perceived to be second skin to the human body since it is in close contact with the human skin most of the times. In hospitals, use of textile materials in different forms and sterilization of these materials is an essential requirement for preventing spread of germs. The need for appropriate disinfection and sterilization techniques is of paramount importance. There has been a continuous demand for novel sterilization techniques appropriate for use on various textile materials as the existing sterilization techniques suffer from various technical and economical drawbacks. Plasma sterilization is the alternative method, which is friendlier and more effective on the wide spectrum of prokaryotic and eukaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species. Plasma exposure can kill micro-organisms on a surface in addition to removing adsorbed monolayer of surface contaminants. Advantages of plasma surface treatment are removal of contaminants from the surface, change in the surface energy and sterilization of the surface. Plasma sterilization aims to kill and/or remove all micro-organisms which may cause infection of humans or animals, or which can cause spoilage of foods or other goods. This review paper emphasizes necessity for sterilization, essentials of sterilization, mechanism of plasma sterilization and the parameters influencing it.

  8. Air and water sterilization using non-thermal plasma

    Microsoft Academic Search

    Nachiket D. Vaze; Krishna P. Arjunan; Michael J. Gallagher; Victor N. Vasilets; Alexander Gutsol; Alexander Fridman; Shivanthi Anandan

    2007-01-01

    The sterilization effect of plasma on air and water were investigated in this study*. For air sterilization, a small scale model of HVAC was designed and Dielectric Barrier Discharge plasma source was used for treatment of air. This PDRF (Pathogen Detection and Remediation Facility) consisted of a circulatory airflow system, a plasma chamber and a sampling system. Air sterilization experiments

  9. Safety and efficacy of hydrogen peroxide plasma sterilization for repeated use of electrophysiology catheters

    Microsoft Academic Search

    Murali N. Bathina; Steve Mickelsen; Conni Brooks; Joe Jaramillo; Trish Hepton; Fred M. Kusumoto

    1998-01-01

    Objectives. The purpose of this study was to evaluate a new technique for sterilizing nonlumen electrophysiology catheters that uses hydrogen peroxide gas plasma.Background. The reuse of electrophysiology catheters may potentially result in a significant cost savings. While ethylene oxide sterilization appears to be safe and effective from a clinical standpoint, toxic ethylene oxide residuals, which exceed Food and Drug Administration

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

    E-print Network

    Paris-Sud XI, Université de

    ,3-7]; investigation of argon plasma 'cleaning' of surfaces has also been made [8-9]. In additionAtmospheric Pressure Humid Argon DBD Plasma for the Application of Sterilization - Measurement. The results of experiments on the use of post-discharge effluent gas of humid argon plasma for sterilization

  11. 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.

  12. Use of Non-Thermal Atmospheric Pressure Plasma for Air Cleaning and Sterilization

    Microsoft Academic Search

    Giyoung Tak; Michael Gallagher; Shailesh Gangoli; Alexander Gutsol; A. Fridman

    2005-01-01

    Summary form only given. Drexel Plasma Institute has several plasma systems for air cleaning and sterilization. High-volume pulsed corona discharge system has been developed as a core of the mobile pilot plant to demonstrate promising technology for treatment of high volume low concentration (HVLC) industrial ventilation streams contaminated by volatile organic compounds (VOC). Gas phase organic compounds can be destroyed

  13. 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.

  14. Simultaneous Sterilization With Surface Modification Of Plastic Bottle By Plasma-Based Ion Implantation

    SciTech Connect

    Sakudo, N.; Ikenaga, N.; Ikeda, F.; Nakayama, Y.; Kishi, Y.; Yajima, Z. [Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusan, Ishikawa 924-0838 (Japan)

    2011-01-07

    Dry sterilization of polymeric material is developed. The technique utilizes the plasma-based ion implantation which is same as for surface modification of polymers. Experimental data for sterilization are obtained by using spores of Bacillus subtilis as samples. On the other hand we previously showed that the surface modification enhanced the gas barrier characteristics of plastic bottles. Comparing the implantation conditions for the sterilization experiment with those for the surface modification, we find that both sterilization and surface modification are simultaneously performed in a certain range of implantation conditions. This implies that the present bottling system for plastic vessels will be simplified and streamlined by excluding the toxic peroxide water that has been used in the traditional sterilization processes.

  15. Effect of ozone on sterilization of Penicillium digitatum using non-equilibrium atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Ohta, Takayuki; Iseki, Sachiko; Ito, Masafumi; Kano, Hiroyuki; Higashijima, Yasuhiro; Hori, Masaru

    2008-10-01

    Methyl bromide has been sprayed to the crops for protecting from insects and virus, but has high ozone depletion potential. Thus, the development of substitute-technology has been strongly required. We have investigated a plasma sterilization for spores of Penicillium digitatum, which causes green mold disease of the crops, using non-equilibrium atmospheric pressure plasma. The sterilization was caused by UV light, ozone, O and OH radicals. In this study, ozone density was measured and the effect to sterilization was discussed. The plasma was generated at an alternative current of 6kV and Ar gas flow rate of 3L/min. In order to investigate the sterilization mechanism of ozone, the absolute density of ozone was measured using ultraviolet absorption spectroscopy and was from 2 to 8 ppm. The sterilization by this plasma was larger than that by the ozonizer (03:600ppm). It is confirmed that the effect of ozone to the sterilization of Penicillium digitatum would be small.

  16. 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.

  17. Rapid Sterilization of Escherichia coli by Solution Plasma Process

    NASA Astrophysics Data System (ADS)

    Andreeva, Nina; Ishizaki, Takahiro; Baroch, Pavel; Saito, Nagahiro

    2012-12-01

    Solution plasma (SP), which is a discharge in the liquid phase, has the potential for rapid sterilization of water without chemical agents. The discharge showed a strong sterilization performance against Escherichia coli bacteria. The decimal value (D value) of the reduction time for E. coli by this system with an electrode distance of 1.0 mm was estimated to be approximately 1.0 min. Our discharge system in the liquid phase caused no physical damage to the E. coli and only a small increase in the temperature of the aqueous solution. The UV light generated by the discharge was an important factor in the sterilization of E. coli.

  18. 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.

  19. Long-distance oxygen plasma sterilization: Effects and mechanisms

    NASA Astrophysics Data System (ADS)

    Liu, Hongxia; Chen, Jierong; Yang, Liqing; Zhou, Yuan

    2008-01-01

    The distribution of electrons, ions and oxygen radicals in long-distance oxygen plasma and the germicidal effect (GE) of Escherichia coli on the surface of medical poly(tetrafluoroethylene) (PTFE) film were studied. The quantity of protein leakage and the production of lipid peroxide in bacterial suspension as well as the state of DNA were measured after sterilization to analyse the inactivation mechanisms. The results showed that the concentration of electrons and ions decreased rapidly with increasing the distance from the center of induction coil, which approximated to 0 at 30 cm, whereas the concentration of oxygen radicals reduced slowly, i.e. decreased 30% within 40 cm. GE value reached 3.42 in the active discharge zone (0 cm) and exceeded 3.32 within 40 cm when plasma treatment parameters were set as follows: plasma rf power at 100 W, treatment time at 60 s and oxygen flux at 40 cm 3/min. Fast etching action on cell membrane by electrons, ions and attacking polyunsaturation fatty acid (PUFA) in cell membrane by oxygen radicals are primary reasons of oxygen plasma sterilization in the active discharge and the afterglow zone, respectively. The GE of UV radiation in long-distance oxygen plasma is feebleness.

  20. Low-temperature low-damage sterilization based on UV radiation through plasma immersion

    NASA Astrophysics Data System (ADS)

    Pollak, J.; Moisan, M.; Kéroack, D.; Boudam, M. K.

    2008-07-01

    This paper introduces a new type of high-frequency (HF) sustained discharge where the HF field applicator is a planar transmission line that allows us to fill with plasma a long chamber of rectangular cross-section (typically 1 m × 15 cm × 5 cm). Peculiar interesting features of this plasma source are a low gas temperature (typically below 40 °C in the 1 Torr range in argon), broadband impedance matching with no need for retuning, stability and reproducibility of the discharge (non-resonant behaviour). This type of plasma source could be useful for web processing; nonetheless, it is applied here to plasma sterilization, taking advantage of its low gas temperature to inactivate microorganisms on polymer-made medical devices to avoid damaging them. The predominant biocide species are the UV photons emitted by the discharge whereas most plasma sterilization techniques call for reactive species such as O atoms and OH molecules, which induce significant erosion damage on polymers. Polystyrene microspheres are actually observed to be erosion-free under the current plasma sterilization conditions (scanning electron micrographs have been examined). Moreover, inactivation is quite fast: 106 B. atrophaeus spores deposited on a Petri dish are inactivated in less than 1 min. Correlation of the UV radiation with the spore inactivation rate is examined by (i) considering the emitted light intensity integrated over the 112-180 nm vacuum UV (VUV) range with a photomultiplier; (ii) looking with an optical spectrometer at the emission spectrum over the 200-400 nm UV range; (iii) using absorption spectroscopy to determine the role of the VUV argon resonant lines (105 and 107 nm) on spore inactivation. It is found that the test-reference spores are mainly inactivated by VUV photons (112-180 nm) that are primarily emitted by impurities present in the argon plasma.

  1. Effect of Dielectric and Liquid on Plasma Sterilization Using Dielectric Barrier Discharge Plasma

    PubMed Central

    Mastanaiah, Navya; Johnson, Judith A.; Roy, Subrata

    2013-01-01

    Plasma sterilization offers a faster, less toxic and versatile alternative to conventional sterilization methods. Using a relatively small, low temperature, atmospheric, dielectric barrier discharge surface plasma generator, we achieved ?6 log reduction in concentration of vegetative bacterial and yeast cells within 4 minutes and ?6 log reduction of Geobacillus stearothermophilus spores within 20 minutes. Plasma sterilization is influenced by a wide variety of factors. Two factors studied in this particular paper are the effect of using different dielectric substrates and the significance of the amount of liquid on the dielectric surface. Of the two dielectric substrates tested (FR4 and semi-ceramic (SC)), it is noted that the FR4 is more efficient in terms of time taken for complete inactivation. FR4 is more efficient at generating plasma as shown by the intensity of spectral peaks, amount of ozone generated, the power used and the speed of killing vegetative cells. The surface temperature during plasma generation is also higher in the case of FR4. An inoculated FR4 or SC device produces less ozone than the respective clean devices. Temperature studies show that the surface temperatures reached during plasma generation are in the range of 30°C–66°C (for FR4) and 20°C–49°C (for SC). Surface temperatures during plasma generation of inoculated devices are lower than the corresponding temperatures of clean devices. pH studies indicate a slight reduction in pH value due to plasma generation, which implies that while temperature and acidification may play a minor role in DBD plasma sterilization, the presence of the liquid on the dielectric surface hampers sterilization and as the liquid evaporates, sterilization improves. PMID:23951023

  2. Sterilizing tissue-materials using pulsed power plasma.

    PubMed

    Heidarkhan Tehrani, Ashkan; Davari, Pooya; Singh, Sanjleena; Oloyede, Adekunle

    2014-04-01

    This paper investigates the potential of pulsed power to sterilize hard and soft tissues and its impact on their physico-mechanical properties. It hypothesizes that pulsed plasma can sterilize both vascular and avascular tissues and the transitive layers in between without deleterious effects on their functional characteristics. Cartilage/bone laminate was chosen as a model to demonstrate the concept, treated at low temperature, at atmospheric pressure, in short durations and in buffered environment using a purposed-built pulsed power unit. Input voltage and time of exposure were assigned as controlling parameters in a full factorial design of experiment to determine physical and mechanical alteration pre- and post-treatment. The results demonstrated that, discharges of 11 kV sterilized samples in 45 s, reducing intrinsic elastic modules from 1.4 ± 0.9 to 0.9 ± 0.6 MPa. There was a decrease of 14.1 % in stiffness and 27.8 % in elastic-strain energy for the top quartile. Mechanical impairment was directly proportional to input voltage (P value < 0.05). Bacterial inactivation was proportional to treatment time for input voltages above 32 V (P < 0.001; R Sq = 0.98). Thermal analysis revealed that helix-coil transition decelerated with exposure time and collagen fibrils were destabilized as denaturation enthalpy reduced by 200 ?V. We concluded by presenting a safe operating threshold for pulsed power plasma as a feasible protocol for effective sterilization of connective tissues with varying level of loss in mechanical robustness which we argue to be acceptable in certain medical and tissue engineering application. PMID:24449024

  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. Understanding the respective roles of UV photons and radicals in cold plasma sterilization

    Microsoft Academic Search

    M. Moisan; B. Saoudi; J. Pelletier; J. Barbeau

    2002-01-01

    Summary form only given. Low-temperature plasma sterilization can be achieved under direct contact with the discharge or in its afterglow. The results to be presented were obtained with B. Subtilis spores subjected to the flowing afterglow of a microwave discharge, at pressures typically below 10 Torrs. As a rule, the sterilization cycle, characterized by the corresponding survival curve (logarithm of

  5. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    PubMed Central

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W.; Jeong, Chang-Mo

    2013-01-01

    PURPOSE Autoclaves and UV sterilizers have been commonly used to prevent cross-infections between dental patients and dental instruments or materials contaminated by saliva and blood. To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated. MATERIALS AND METHODS After inoculating E. coli and B. subtilis the diamond burs and polyvinyl siloxane materials were sterilized by exposing them to the plasma for different lengths of time (30, 60, 90, 120, 180 and, 240 seconds). The diamond burs and polyvinyl siloxane materials were immersed in PBS solutions, cultured on agar plates and quantified by counting the colony forming units. The data were analyzed using one-way ANOVA and significance was assessed by the LSD post hoc test (?=0.05). RESULTS The device was effective in killing E. coli contained in the plasma device compared with the UV sterilizer. The atmospheric pressure non-thermal air plasma device contributed greatly to the sterilization of diamond burs and polyvinyl siloxane materials inoculated with E. coli and B. subtilis. Diamond burs and polyvinyl siloxane materials inoculated with E. coli was effective after 60 and 90 seconds. The diamond burs and polyvinyl siloxane materials inoculated with B. subtilis was effective after 120 and 180 seconds. CONCLUSION The atmospheric pressure non-thermal air plasma device was effective in killing both E. coli and B. subtilis, and was more effective in killing E. coli than the UV sterilizer. PMID:23508991

  6. Confirmation of the sterilization effect using a high concentration of ozone gas for the bio-clean room.

    PubMed

    Iwamura, Takuji; Nagano, Katsunori; Nogami, Toshihiro; Matsuki, Noritomo; Kosaka, Noriyoshi; Shintani, Hideharu; Katoh, Miyoshi

    2013-01-01

    A high-level aseptic environment must be maintained in bio-cleanrooms used for the manufacture of sterile products. In the past, formaldehyde gas was most commonly used to sterilize bio-cleanrooms, but due to strict residual limitations there has been a need to develop a less toxic alternative choice. The authors have developed a revolutionary new sterilization system using a high concentration of ozone gas and used this system to sterilize an actual bio-cleanroom. This system integrates the ozone gas generator with the air conditioning system by proper control. The design specifications for the system included an ozone gas concentration of 200 ppm or more, relative humidity of 80% or more, and a sterilizing time of 120 min. Blow vents and suction ports were placed to ensure a uniform airflow which would extend through the entire room during ozone gas sterilization. Tests regarding long-term material exposure to ozone gas were conducted when the system was introduced to distinguish usable and unusable materials. In an actually constructed cleanroom, simulations were used to predict the evenness of the diffusion of ozone gas concentration and relative humidity during ozone gas sterilization, and measurements of the actual indoor ozone gas concentration, temperature and relative humidity during sterilization revealed that the ozone concentration and relative humidity needed for sterilization had been achieved generally throughout the entire environment. In addition, the CT value (mg/m(3) (=ppm) × min) , derived by multiplying the ozone gas concentration during ozone gas sterilization by the sterilization time, was equal to or greater than the target value of 24 × 10(3) (ppm·min) . When the results of sterilization in a cleanroom were confirmed using a biological indicator (BI) , negative results were obtained at all measurement points, demonstrating that sterilization was being performed effectively in the actual factory at which the ozone gas sterilization system had been introduced. PMID:23538847

  7. Gas lens laser produced plasma.

    PubMed

    Notcutt, M; Waltham, J A; Michaelis, M M; Cunningham, P F; Cazalet, R S

    1989-07-01

    A gas lens is used to focus a megawatt ruby laser beam on to a target to create a plasma. By using focal plane photographs and Faraday cup plasma diagnostics, the focusing ability of a gas lens is compared with an equivalent glass lens. In this experiment the gas lens compares favorably when the laser beam has a divergence of ~1 mrad. PMID:20555544

  8. 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.

  9. Sterilization of contaminated matter with an atmospheric pressure plasma

    Microsoft Academic Search

    Mounir Laroussi

    1996-01-01

    The primary methods now used to sterilize contaminated media (infectious waste, tools, liquids, ...) are exposure to UV radiation, incineration, or autoclaving. These methods have recently raised public controversies concerning their environmental effects and other health issues. In an attempt to eliminate these drawbacks, new approaches based on different technologies are being investigated. Irradiation by electron beam is an example

  10. Plasma Sterilization of Poly Lactic Acid Ultrasound Contrast Agents: Surface Modification and Implications for Drug Delivery

    PubMed Central

    Eisenbrey, John R.; Hsu, Jennifer; Wheatley, Margaret A.

    2013-01-01

    Poly lactic acid (PLA) ultrasound contrast agents (CA) have been previously developed in our laboratory for ultrasound (US) imaging, as well as surface coated with doxorubicin to create a potential targeted platform of chemotherapeutic delivery using focused US. However, we have previously found it impossible to sterilize these agents while at the same time maintaining their acoustic properties, a task that would probably require fabrication within a clean facility. The purpose of this paper is to investigate the feasibility of using plasma to sterilize these CA while maintaining maximum echogenicity, a step that would greatly facilitate in vivo investigations. Effects of plasma exposure time (1, 3 and 6 minutes) and intensity (low- 10 mA, 6.8 W; medium- 15 mA, 10.5 W; and high- 25 mA, 18W) on the CA’s acoustic properties, surface morphology, zeta potential, capacity to carry chemotherapeutics, and overall sterility are described. Both increases in plasma intensity and exposure time increased CA zeta potential and also significantly increased drug payload. High intensity plasma exposure for three minutes was found to be an optimal sterilization protocol for maximal (100%) preservation of CA echogenicity. Plasma exposure resulted in sterile samples and maintained original CA enhancement of 20 dB and acoustic half-life over 75 minutes, while increasing CA zeta potential by 11 mV and doxorubicin loading efficiency by 10%. This study not only shows how a highly temperature and pressure sensitive agent can be sterilized using plasma, but also that surface modification can be used to increase surface binding of drug. PMID:19766380

  11. The sterilization of Escherichia coli by dielectric-barrier discharge plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Miao, Hu; Yun, Guo

    2011-06-01

    The sterilization of E. coli (ATCC8099) using an atmospheric pressure, air DBD plasma driven by 100 Hz high-voltage power supply was investigated in this paper. The results showed that germicidal efficiency was closely related to the plasma treatment time, the gap spacing, the initial cell density and the surface characters of substrate materials. The germicidal efficiency was 99.999% under the conditions of 5-min plasma treatment, 3-cm gap spacing and on PET films. After plasma exposure for 5 min, the temperature was observed below 43 °C which could not lead to inactivate E. coli. The observation of protein leakage and cell morphology alteration by transmission electron microscopy (TEM) techniques revealed that the etching action on cell membrane by electrons, ions and radicals was primary reason of DBD air plasma sterilization.

  12. Sterilization of Materials with a One Atmosphere Uniform Glow Discharge Plasma.*

    NASA Astrophysics Data System (ADS)

    Ku, Yongmin; Brickman, C.; Tosh, K.; Kelly-Wintenberg, K.; Montie, T. C.; Tsai, P.; Wadsworth, L.; Roth, J. Reece

    1996-11-01

    The relatively recent development of the One Atmosphere Uniform Glow Discharge Plasma sterilization technique at the UTK Plasma Science Laboratory has produced initial results which indicate that the technique may have commercial potential. We have shown that active species in a OAUGDP can be applied to the sterilization of fabrics, films, solid materials, and microbiological culture media. With a OAUGDP, we can eliminate the vacuum system which enforces batch processing and requires a continuous input of electrical power. With a OAUGDP, the exposure time is as little as 15 seconds. Sterilization of microorganisms with a kill ratio of 10E6 or higher, can be achieved with minimal unwanted byproducts and at less expense, compared to such conventional sterilization methods as autoclaving, ethylene oxide, or low pressure plasma treatment. This paper discusses the sterilization mechanisms of this new technique, and compares its advantages and disadvantages with other widely used techniques. ^1 Department of Microbiology, UTK ^2 UTK Textiles and Nonwovens Development Center (TANDEC) Research supported in part by the UTK Textiles and Nonwovens Development Center and UTK Center for Materials Processing.

  13. 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.

  14. Radiative decay of keV-mass sterile neutrinos in a strongly magnetized plasma

    E-print Network

    Alexandra A. Dobrynina; Nicolay V. Mikheev; Georg G. Raffelt

    2015-01-07

    The radiative decay of sterile neutrinos with typical masses of 10 keV is investigated in the presence of a strong magnetic field and degenerate plasma. Full account is taken of the strongly modified photon dispersion relation relative to vacuum. The limiting cases of relativistic and non-relativistic plasma are analyzed. The decay rate in a strongly magnetized plasma as a function of the electron number density is compared with the un-magnetized case. We find that a strong magnetic field suppresses the catalyzing influence of the plasma on the decay rate.

  15. A remote exposure reactor (RER) for plasma processing and sterilization by plasma active species at one atmosphere

    Microsoft Academic Search

    J. Reece Roth; Daniel M. Sherman; Rami Ben Gadri; Fuat Karakaya; Zhiyu Chen; Thomas C. Montie; Kimberly Kelly-Wintenberg; P. P.-Y. Tsai

    2000-01-01

    We have developed a remote exposure reactor (RER) in which the active species of air and other gases responsible for sterilization and processing effects are generated on flat panels in a surface layer of one atmosphere uniform glow discharge plasma (OAUGDP). These active species are convected by forced airflow at one atmosphere and near room temperature to a remote exposure

  16. 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

  17. 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

  18. The cold and atmospheric-pressure air surface barrier discharge plasma for large-area sterilization applications

    SciTech Connect

    Wang Dacheng [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Zhao Di [Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Photoelectrical Engineering, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Feng Kecheng [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Zhang Xianhui [Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu Dongping [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Department of Aeronautics, Fujian Key Laboratory for 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); Yang Size [Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

    2011-04-18

    This letter reports a stable air surface barrier discharge device for large-area sterilization applications at room temperature. This design may result in visually uniform plasmas with the electrode area scaled up (or down) to the required size. A comparison for the survival rates of Escherichia coli from air, N{sub 2} and O{sub 2} surface barrier discharge plasmas is presented, and the air surface plasma consisting of strong filamentary discharges can efficiently kill Escherichia coli. Optical emission measurements indicate that reactive species such as O and OH generated in the room temperature air plasmas play a significant role in the sterilization process.

  19. Impact of Chlorine Dioxide Gas Sterilization on Nosocomial Organism Viability in a Hospital Room

    PubMed Central

    Lowe, John J.; Gibbs, Shawn G.; Iwen, Peter C.; Smith, Philip W.; Hewlett, Angela L.

    2013-01-01

    To evaluate the ability of ClO2 to decontaminate pathogens known to cause healthcare-associated infections in a hospital room strains of Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Mycobacterium smegmatis, and Staphylococcus aureus were spot placed in duplicate pairs at 10 sites throughout a hospital room and then exposed to ClO2 gas. Organisms were collected and evaluated for reduction in colony forming units following gas exposure. Six sterilization cycles with varied gas concentrations, exposure limits, and relative humidity levels were conducted. Reductions in viable organisms achieved ranged from 7 to 10-log reductions. Two sterilization cycles failed to produce complete inactivation of organisms placed in a bathroom with the door closed. Reductions of organisms in the bathroom ranged from 6-log to 10-log reductions. Gas leakage between hospital floors did not occur; however, some minor gas leakage from the door of hospital room was measured which was subsequently sealed to prevent further leakage. Novel technologies for disinfection of hospital rooms require validation and safety testing in clinical environments. Gaseous ClO2 is effective for sterilizing environmental contamination in a hospital room. Concentrations of ClO2 up to 385 ppm were safely maintained in a hospital room with enhanced environmental controls. PMID:23792697

  20. Impact of chlorine dioxide gas sterilization on nosocomial organism viability in a hospital room.

    PubMed

    Lowe, John J; Gibbs, Shawn G; Iwen, Peter C; Smith, Philip W; Hewlett, Angela L

    2013-06-01

    To evaluate the ability of ClO2 to decontaminate pathogens known to cause healthcare-associated infections in a hospital room strains of Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Mycobacterium smegmatis, and Staphylococcus aureus were spot placed in duplicate pairs at 10 sites throughout a hospital room and then exposed to ClO2 gas. Organisms were collected and evaluated for reduction in colony forming units following gas exposure. Six sterilization cycles with varied gas concentrations, exposure limits, and relative humidity levels were conducted. Reductions in viable organisms achieved ranged from 7 to 10-log reductions. Two sterilization cycles failed to produce complete inactivation of organisms placed in a bathroom with the door closed. Reductions of organisms in the bathroom ranged from 6-log to 10-log reductions. Gas leakage between hospital floors did not occur; however, some minor gas leakage from the door of hospital room was measured which was subsequently sealed to prevent further leakage. Novel technologies for disinfection of hospital rooms require validation and safety testing in clinical environments. Gaseous ClO2 is effective for sterilizing environmental contamination in a hospital room. Concentrations of ClO2 up to 385 ppm were safely maintained in a hospital room with enhanced environmental controls. PMID:23792697

  1. Acid etching and plasma sterilization fail to improve osseointegration of grit blasted titanium implants.

    PubMed

    Saksø, Mikkel; Jakobsen, Stig S; Saksø, Henrik; Baas, Jørgen; Jakobsen, Thomas; Søballe, Kjeld

    2012-01-01

    Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation.The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time.Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner. PMID:22962567

  2. Acid Etching and Plasma Sterilization Fail to Improve Osseointegration of Grit Blasted Titanium Implants

    PubMed Central

    Saksø, Mikkel; Jakobsen, Stig S; Saksø, Henrik; Baas, Jørgen; Jakobsen, Thomas; Søballe, Kjeld

    2012-01-01

    Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation. The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time. Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner. PMID:22962567

  3. Molecular stability, mechanical properties, surface characteristics and sterility of biodegradable polyurethanes treated with low-temperature plasma

    Microsoft Academic Search

    Katarzyna Gorna; Sylwester Gogolewski

    2003-01-01

    Biodegradable medical polyurethanes with varying hydrophilic-to-hydrophobic segment ratios based on hydrophilic poly(ethylene oxide) and hydrophobic poly(?-caprolactone) diol, were treated with low-temperature, low-pressure plasmas of hydrogen peroxide, oxygen, carbon dioxide and ammonia. All samples treated with hydrogen peroxide plasma were sterile, while samples treated with oxygen, carbon dioxide and ammonia plasmas were nonsterile. The treatment caused a 7% drop in molecular

  4. Plasma wakefield acceleration in self-ionized gas or plasmas.

    PubMed

    Deng, S; Barnes, C D; Clayton, C E; O'Connell, C; Decker, F J; Erdem, O; Fonseca, R A; Huang, C; Hogan, M J; Iverson, R; Johnson, D K; Joshi, C; Katsouleas, T; Krejcik, P; Lu, W; Marsh, K A; Mori, W B; Muggli, P; Tsung, F

    2003-10-01

    Tunnel ionizing neutral gas with the self-field of a charged particle beam is explored as a possible way of creating plasma sources for a plasma wakefield accelerator [Bruhwiler et al., Phys. Plasmas (to be published)]. The optimal gas density for maximizing the plasma wakefield without preionized plasma is studied using the PIC simulation code OSIRIS [R. Hemker et al., in Proceeding of the Fifth IEEE Particle Accelerator Conference (IEEE, 1999), pp. 3672-3674]. To obtain wakefields comparable to the optimal preionized case, the gas density needs to be seven times higher than the plasma density in a typical preionized case. A physical explanation is given. PMID:14683089

  5. Room temperature sterilization of surfaces and fabrics with a one atmosphere uniform glow discharge plasma.

    PubMed

    Kelly-Wintenberg, K; Montie, T C; Brickman, C; Roth, J R; Carr, A K; Sorge, K; Wadsworth, L C; Tsai, P P

    1998-01-01

    We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). This newly-invented source of glow discharge plasma (the fourth state of matter) is capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial active species to surfaces and workpieces at room temperature as judged by viable plate counts. OAUGDP exposures have reduced log numbers of bacteria, Staphylococcus aureus and Escherichia coli, and endospores from Bacillus stearothermophilus and Bacillus subtilis on seeded solid surfaces, fabrics, filter paper, and powdered culture media at room temperature. Initial experimental data showed a two-log10 CFU reduction of bacteria when 2 x 10(2) cells were seeded on filter paper. Results showed > or = 3 log10 CFU reduction when polypropylene samples seeded with E. coli (5 x 10(4)) were exposed, while a 30 s exposure time was required for similar killing with S. aureus-seeded polypropylene samples. The exposure times required to effect > or = 6 log10 CFU reduction of E. coli and S. aureus on polypropylene samples were no longer than 30 s. Experiments with seeded samples in sealed commercial sterilization bags showed little or no differences in exposure times compared to unwrapped samples. Plasma exposure times of less than 5 min generated > or = 5 log10 CFU reduction of commercially prepared Bacillus subtilis spores (1 x 10(5)); 7 min OAUGDP exposures were required to generate a > or = 3 log10 CFU reduction for Bacillus stearothermophilus spores. For all microorganisms tested, a biphasic curve was generated when the number of survivors vs time was plotted in dose-response cures. Several proposed mechanisms of killing at room temperature by the OAUGDP are discussed. PMID:9523458

  6. Effect of Dielectric and Liquid on Plasma Sterilization Using Dielectric Barrier Discharge Plasma

    E-print Network

    Roy, Subrata

    temperature plasmas generated from room air. Depending on the applied voltage and discharge current, different densities. Fabricated plasmas are ionized gases, made up of ions, electrons and neutrals. These are commonly

  7. TOPICAL REVIEW: Striations in rare gas plasmas

    Microsoft Academic Search

    Vladimir I. Kolobov

    2006-01-01

    This paper describes the recent progress in understanding the nature of striations in rare gas plasmas. Striations are ionization waves with unique properties determined by transport phenomena, ionization processes and electron kinetics in current-carrying plasmas. Recent progress in understanding the physics of striations is mainly associated with the advances of non-local electron kinetics in spatially inhomogeneous plasmas and the development

  8. Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.

    PubMed

    Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

    2013-09-01

    The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements. PMID:23794223

  9. Maxwell Prize Session: Hot Plasma Effects in Gas Discharge Plasma

    Microsoft Academic Search

    Valery Godyak

    2004-01-01

    Radio frequency (rf) gas discharges have been known for over a century. Recently, interest in low-pressure rf discharges has been revitalized due to great achievements and expectations in using such devices in plasma processing for manufacturing of semiconductor chips and lighting technology. In rf discharges the dominant interaction of the electromagnetic field with the plasma, and thus rf power absorption,

  10. Neutral Gas Plasma Interactions in Space Plasma

    Microsoft Academic Search

    Kan Liou

    1994-01-01

    A sounding rocket experiment, CRIT-II, involving the injection of shaped-charge barium in ionospheric plasma was conducted on May 7, 1989, to investigate Alfven's critical ionization velocity (CIV) hypothesis in space. The CRIT -II main payload was instrumented to make in situ measurements within the neutral barium beam. Among the detectors, UNH provided three energetic particle detectors and two photometers. The

  11. Application of Plasma on Reentry Vehicle Communication and Interplanetary Spacecraft Sterilization

    NASA Astrophysics Data System (ADS)

    Fenstermacher, Jarrod J.

    In order to gain a better understanding of the reactions occurring during reentry at the gas-surface interface, a reactive ion etch (RIE) plasma device was augmented to more accurately represent how material may paralyze in the presence of plasma. The device inflow was augmented to include a nitrogen line, and the outflow augmented to allow chemical analysis. A nichrome resistor heater was added to raise sample temperatures to pyrolysis levels. Cryo-focusing was performed on pyrolysis gases in order to test the ability to quantify compounds released during heating. This was done using liquid nitrogen prior to compounds entering the gas chromatography column. The nitrogen line also allowed initial study into the use of the RIE machine for planetary protection experiments due to the biocidal properties of Nitrogen/Oxygen plasma. This included static build-up experiments on equipment sensitive to electrostatic discharge. Experiments were also carried out using George Washington University's Vacuum Arc Thruster (VAT). The VAT was used in an attempt to catalyze spallation from a silicon phenolic thermal protection system material (TPS).

  12. Plasma formation in underwater gas bubbles

    NASA Astrophysics Data System (ADS)

    Sommers, B. S.; Foster, J. E.

    2014-02-01

    The generation of plasma in underwater gas bubbles offers the potential to produce large volume plasma in water while minimizing electrode erosion. Such attributes are desirable for the design of plasma-based water purification systems. In this work, gas bubbles of diameter 0.4-0.7 mm were trapped in the node of a 26.4 kHz underwater acoustic standing wave and pulsed with voltages in the range 10-14 kV. Plasma formation in trapped, isolated bubbles was observed to occur through two separate pathways: (1) plasma generated in the bubble through impact by a liquid streamer and (2) plasma generated in the bubble due solely to the applied electric field. The former case demonstrates the mechanism of so-called streamer hopping in which the discharge transitions from a water streamer to a gaseous surface streamer. Perturbations of the bubble's fluid boundary due to the streamer are also discussed.

  13. EDITORIAL: Gas plasmas in biology and medicine

    NASA Astrophysics Data System (ADS)

    Stoffels, Eva

    2006-08-01

    It is my great pleasure to introduce this special cluster devoted to recent developments in biomedical plasma technology. It is an even greater pleasure to behold the enormous progress which has been made in this area over the last five years. Research on biomedical plasma applications proceeds hand in hand with the development of new material processing technologies, based on atmospheric plasma sources. In the beginning, major research effort was invested in the development and control of new plasma sources—in this laborious process, novel devices were constructed and characterized, and also new plasma physical phenomena were discovered. Self-constriction of micro-plasmas, pattern formation, filamentation of glow discharges and various mode transitions are just a few examples. It is a real challenge for theorists to gain an understanding of these complex phenomena. Later, the devices had to be thoroughly tested and automated, and various safety issues had to be addressed. At present, many atmospheric plasma sources are ready to use, but not all fundamental and technical problems have been resolved by far. There is still plenty of room for improvement, as in any dynamic area of research. The recent trends are clear: the application area of plasmas expands into processing of unconventional materials such as biological scaffolds, and eventually living human, animal and plant tissues. The gentle, precise and versatile character of cold plasmas simply invites this new application. Firstly, non-living surfaces have been plasma-treated to attain desired effects in biomedical research; tissue engineering will soon fully profit from this powerful technique. Furthermore, studies on cultured plant and animal cells have provided many findings, which are both fundamentally interesting and potentially applicable in health care, veterinary medicine and agriculture. The most important and hitherto unique property of plasma treatment is that it can evade accidental cell death and its attendant complications, such as inflammation and scarring. Another substantial research direction makes use of the bactericidal properties of the plasma. The number of findings on plasma inactivation of bacteria and spores is growing; plasma sterilization has already achieved some commercial success. In future, bacteriostatic properties of cold plasmas will even facilitate non-contact disinfection of human tissues. At this moment, one cannot explicitly list all the medical procedures in which cold plasmas will be involved. My personal intuition predicts widespread use of plasma treatment in dentistry and dermatology, but surely more applications will emerge in the course of this multi-disciplinary research. In fact, some plasma techniques, such as coagulation and coblation, are already used in clinical practice—this is another image of plasma science, which is so far unfamiliar to plasma physicists. Therefore, this particular topic forms a perfect platform for contacts between physicists and medical experts. Our colleagues from the medical scientific community will continue giving us feedback, suggestions or even orders. Biomedical plasmas should not become an isolated research area—we must grow together with medical research, listen to criticism, and eventually serve the physicians. Only then will this new field grow, flourish and bear fruit. All the above-mentioned topics meet in this issue of Journal of Physics D: Applied Physics, comprising the most significant examples of modern biomedical plasma research. Browsing through the contributions, the reader can trace back the progress in this field: from fundamental physical (numerical) studies, through phenomenology and physics of new discharges, studies on plasma-surface modification, bacterial inactivation tests, fundamental cell biological investigations, to final in vivo applications. One may ask why this selection has found its place in a purely physical journal—many contributions are concerned with (micro)-biology rather than physics. To me, the answer is clear: it is important to maintain t

  14. Postpartum Sterilization

    MedlinePLUS

    ... is called tubal sterilization. In tubal sterilization, the fallopian tubes are closed off. Tubal sterilization prevents the egg ... incisions made in the mother’s abdomen and uterus. Fallopian Tubes: Tubes through which an egg travels from the ...

  15. Maxwell Prize Session: Hot Plasma Effects in Gas Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Godyak, Valery

    2004-11-01

    Radio frequency (rf) gas discharges have been known for over a century. Recently, interest in low-pressure rf discharges has been revitalized due to great achievements and expectations in using such devices in plasma processing for manufacturing of semiconductor chips and lighting technology. In rf discharges the dominant interaction of the electromagnetic field with the plasma, and thus rf power absorption, takes place in the plasma boundary layer (near the electrode sheath in a capacitive and in the skin layer in an inductive rf discharge). The interaction of the electromagnetic field with plasma can be of local or nonlocal character. In the first case, there is local coupling between the rf current and the electric field described by a local complex conductivity tensor of a cold plasma. That corresponds to traditional (collisional) gas discharge physics. In the second case, electron thermal motion brings spatial dispersion into the relation between the rf current and the electric field, so that the conductivity tensor becomes a nonlocal operator. Stochastic (collisionless) electron heating, anomalous skin effect and a variety of plasma kinetic and nonlinear effects are typical for low-pressure rf discharges operating in the regime of nonlocal electrodynamics. Such phenomena are characteristic of hot fusion and space plasmas, where they are usually observed experimentally as some global effects. The ability to reproduce these phenomena in a table-top rf discharge experiment (equipped with spatially resolved electron kinetic and electromagnetic field diagnostics) makes the rf discharge a unique playground for basic plasma studies highly amenable to theoretical analysis. The subject of this talk is a review of nonlocal and nonlinear effects found in rf discharge experiments and theoretical analysis, where the interaction of electromagnetic field with plasma is controlled by the electron thermal motion rather than the electron-atom collisions. New features in the electron energy distribution, wave phase bifurcation and phase velocity reversal, collisionless and negative power absorption, harmonic generation and ponderomotive effect are found in these experiments and interpreted in terms of non-local, hot electron electrodynamics.

  16. Fundamentals of gas phase plasmas for treatment of human tissue.

    PubMed

    Kushner, Mark J; Babaeva, Natalia Yu

    2011-01-01

    The use of gas phase plasmas for treating human tissue is at the intersection of two disciplines - plasma physics and engineering, and medicine. In this paper, a primer will be provided for the medical practitioner on the fundamentals of generating gas phase plasmas at atmospheric pressure in air for the treatment of human tissue. The mechanisms for gas phase plasmas interacting with tissue and biological fluids will also be discussed using results from computer modeling. PMID:21335808

  17. Investigation of a plasma opening switch using a gas discharge plasma source

    Microsoft Academic Search

    J. J. Moschella; R. C. Hazelton; T. B. Settersten; G. G. Spanjers; E. J. Yadlowsky; I. Henins

    1993-01-01

    Summary form only given. A coaxial, Marshall type plasma gun is currently being used as a plasma source in an experiment with a plasma opening switch (POS). It has been suggested that a single, gas-driven plasma injector can replace one or more flashboards. The initial experiments are underway with a prototype gun, in which gas is injected into the system

  18. FAST TRACK COMMUNICATION: On the application of inductively coupled plasma discharges sustained in Ar/O2/N2 ternary mixture for sterilization and decontamination of medical instruments

    NASA Astrophysics Data System (ADS)

    Stapelmann, K.; Kylián, O.; Denis, B.; Rossi, F.

    2008-10-01

    Non-equilibrium low pressure-plasma discharges are extensively studied for their high potential in the field of sterilization and decontamination of medical devices. This increased interest in plasma discharges arises from, among other reasons, their capability not only to inactivate bacterial spores but also to eliminate, destroy or remove pathogenic biomolecules and thus to provide a one-step process assuring safety of treated instruments. However, recent studies have shown that optimal conditions leading to inactivation of spores and physical removal of pathogens differ significantly—the efficiency of spores sterilization is above all dependent on the UV radiation intensity, whereas high etching rates are connected with the presence of the etching agent, typically atomic oxygen. The aim of this contribution is to discuss and demonstrate the feasibility of Ar/N2/O2 low-pressure inductively coupled plasma discharges as an option to provide intense UV radiation while maintaining the high etching rates of biomolecules.

  19. Fuel gas production by microwave plasma in liquid

    SciTech Connect

    Nomura, Shinfuku; Toyota, Hiromichi; Tawara, Michinaga; Yamashita, Hiroshi; Matsumoto, Kenya [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan); Shikoku Industry and Technology Promotion Center, 2-5 Marunouchi, Takamatsu, Kagawa 760-0033 (Japan)

    2006-06-05

    We propose to apply plasma in liquid to replace gas-phase plasma because we expect much higher reaction rates for the chemical deposition of plasma in liquid than for chemical vapor deposition. A reactor for producing microwave plasma in a liquid could produce plasma in hydrocarbon liquids and waste oils. Generated gases consist of up to 81% hydrogen by volume. We confirmed that fuel gases such as methane and ethylene can be produced by microwave plasma in liquid.

  20. 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.

  1. Weak turbulence theory of enhanced gas ionization by plasma flow

    Microsoft Academic Search

    A. A. Galeev

    1981-01-01

    A quasilinear theory of collisionless energy transfer from a counterstreaming plasma-gas flow to electrons is presented. The critical ionization velocity was reexamined. It is recognized that this phenomenon requires enhanced heating of electrons, via some hypothetical collisionless interaction between plasma species, that can be studied by a well developed weak plasma turbulence theory. Since a plasma cannot interact collisionlessly with

  2. Reversible Sterilization

    ERIC Educational Resources Information Center

    Largey, Gale

    1977-01-01

    Notes that difficult questions arise concerning the use of sterilization for alleged eugenic and euthenic purposes. Thus, how reversible sterilization will be used with relation to the poor, mentally ill, mentally retarded, criminals, and minors, is questioned. (Author/AM)

  3. 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.

  4. Speciation analysis by gas chromatography with plasma source spectrometric detection

    NASA Astrophysics Data System (ADS)

    ?obi?ski, Ryszard; Adams, Freddy C.

    State-of-the-art species-selective analysis by gas chromatography (GC) with plasma source spectrometric detection is discussed for organometal and organometalloid compounds. Various plasmas, inductively coupled plasma, microwave induced plasma, capacitatively coupled plasma, direct current plasma and alternating current plasma, are characterized and critically compared as sources of radiation for atomic emission spectrometry and sources of ions for mass spectrometry. Interfaces between gas chromatography (packed, wide-bore, capillary and multicapillary) and plasma source spectrometry are characterized. Particular emphasis is given to applications of GC with plasma source detection to real-world analytical problems, which are comprehensively reviewed. The use of plasmas for the acquisition of auxiliary molecular information such as empirical formulae and structural information is discussed. Recent developments relating to sample preparation and presentation to the hyphenated system are addressed. The most significant trends in speciation analysis are highlighted.

  5. Sterilization/disinfection using reduced-pressure plasmas: some differences between direct exposure of bacterial spores to a discharge and their exposure to a flowing afterglow

    NASA Astrophysics Data System (ADS)

    Moisan, M.; Levif, P.; Séguin, J.; Barbeau, J.

    2014-07-01

    The use of plasma for sterilization or disinfection offers a promising alternative to conventional steam or chemical approaches. Plasma can operate at temperatures less damaging to some heat-sensitive medical devices and, in contrast to chemicals, can be non-toxic and non-polluting for the operator and the environment, respectively. Direct exposure to the gaseous discharge (comprising an electric field and ions/electrons) or exposure to its afterglow (no E-field) can both be envisaged a priori, since these two methods can achieve sterility. However, important issues must be considered besides the sterility goal. Direct exposure to the discharge, although yielding a faster inactivation of microorganisms, is shown to be potentially more aggressive to materials and sometimes subjected to the shadowing effect that precludes the sterilization of complex-form items. These two drawbacks can be successfully minimized with an adequate flowing-afterglow exposure. Most importantly, the current paper shows that direct exposure to the discharge can lead to the dislodgment and release of viable microorganisms from their substratum. Such a phenomenon could be responsible for the recontamination of sterilized devices as well as possible contamination of the ambient surroundings, additionally yielding an erroneous over-appreciation of the inactivation efficiency. The operation of the N2-O2 flowing afterglow system being developed in our group is such that there are no ions and electrons left in the process chamber (late-afterglow regime) in full contrast with their presence in the discharge. The dislodgment and release of spores could be attributed, based on the literature, to their electrostatic charging by electrons, leading to an (outward) electrostatic stress that exceeds the adhesion of the spores on their substrate.

  6. STW gas sensors using plasma-polymerized allylamine

    Microsoft Academic Search

    Hiromi Yatsuda; Makoto Nara; Takashi Kogai; Hidenobu Aizawa; Shigeru Kurosawa

    2007-01-01

    Gas sensors generally consist of two major components: a gas recognition element which provides the specificity and selectivity of the measurement and a physical transducer which translates the gas absorption or desorption event into electronic signal. In this paper, plasma polymerized allylamine (PPAa) film is used as a gas recognition element and a surface transverse wave (STW) device is used

  7. The Use of Liquid Isopropyl Alcohol and Hydrogen Peroxide Gas Plasma to Biologically Decontaminate Spacecraft Electronics

    NASA Technical Reports Server (NTRS)

    Bonner, J. K.; Tudryn, Carissa D.; Choi, Sun J.; Eulogio, Sebastian E.; Roberts, Timothy J.; Tudryn, Carissa D.

    2006-01-01

    Legitimate concern exists regarding sending spacecraft and their associated hardware to solar system bodies where they could possibly contaminate the body's surface with terrestrial microorganisms. The NASA approved guidelines for sterilization as set forth in NPG 8020.12C, which is consistent with the biological contamination control objectives of the Committee on Space Research (COSPAR), recommends subjecting the spacecraft and its associated hardware to dry heat-a dry heat regimen that could potentially employ a temperature of 110(deg)C for up to 200 hours. Such a temperature exposure could prove detrimental to the spacecraft electronics. The stimulated growth of intermetallic compounds (IMCs) in metallic interconnects and/or thermal degradation of organic materials composing much of the hardware could take place over a prolonged temperature regimen. Such detrimental phenomena would almost certainly compromise the integrity and reliability of the electronics. Investigation of sterilization procedures in the medical field suggests that hydrogen peroxide (H202) gas plasma (HPGP) technology can effectively function as an alternative to heat sterilization, especially for heat-sensitive items. Treatment with isopropyl alcohol (IPA) in liquid form prior to exposure of the hardware to HPGP should also prove beneficial. Although IPA is not a sterilant, it is frequently used as a disinfectant because of its bactericidal properties. The use of IPA in electronics cleaning is widely recognized and has been utilized for many years with no adverse affects reported. In addition, IPA is the principal ingredient of the test fluid used in ionic contamination testers to assess the amount of ionic contamination found on the surfaces of printed wiring assemblies. This paper will set forth experimental data confirming the feasibility of the IPA/H202 approach to reach acceptable microbial reduction (MR) levels of spacecraft electronic hardware. In addition, a proposed process flow in which both IPA liquid and HPGP are utilized will be presented in Section 7.0.

  8. 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.

  9. 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.

  10. Decomposition of tetrodotoxin using multi-gas plasma jet.

    PubMed

    Takamatsu, Toshihiro; Miyahara, Hidekazu; Azuma, Takeshi; Okino, Akitoshi

    2014-04-01

    In this study, non-thermal multi-gas plasma treatments were performed for Tetrodotoxin (TTX) solution, and TTX decomposition was analyzed by liquid chromatography coupled with electrospray time-of-flight mass spectrometry. The TTX mass spectrum signal was reduced by plasma irradiations to different levels by using various gas species. Nitrogen plasma exhibited the optimal capability for TTX decomposition, followed by oxygen, argon, and carbon dioxide plasmas. The TTX concentration decreased 100-fold by nitrogen plasma treatment for 10 min. PMID:24646709

  11. Dusty Plasma Structures in Gas Mixtures

    SciTech Connect

    Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya Str. 13/19, build 2, 125412 Moscow (Russian Federation); Maiorov, S. A. [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str. 38, 119991 Moscow (Russian Federation)

    2008-09-07

    The possibility of attainment of large Mach numbers is analyzed for the case of heavy ions drifting in a light gas. Under conditions of typical experiments with dust structures in plasmas, the use of the mixture of light and heavy gases is shown to make it possible to suppress the ion heating in the electric field and to form supersonic flows characterized by large Mach numbers. The drift of krypton ions in helium is considered as an example. Experiments with dc glow discharge at 1-10% of Kr show that the transition to the discharge in mixture leads to increase of interaction anisotropy and reinforcement of coupling of dust particles in the direction of ion drift. On the other hand, under certain conditions the phenomenon of abnormal 'heating' of dust particles was observed when the particles can obtain high kinetic energy which is several orders of magnitude higher than typical.

  12. Fiberoptic Interferometer For Gas and Plasma Density Measurements

    Microsoft Academic Search

    Alex Bixler; Michael McFarland; Mahadevan Krishnan; Philip Coleman; John Thompson; Dominique Huet

    2003-01-01

    Optical interferometry is a powerful tool for mapping gas and plasma distributions in supersonic nozzles, plasma opening switches and other pulsed gas\\/plasma environments. We have developed a versatile, robust and portable interferometer to make such measurements. The Fiberoptic Interferometer (FOI) is built from off-the-shelf communications-grade (near IR, 1.55 microns) fiber components. The system was designed to also permit two-color operation.

  13. Sterilization System

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Cox Sterile Products, Inc.'s Rapid Heat Transfer Sterilizer employs a heat exchange process that induces rapid air movement; the air becomes the heat transfer medium, maintaining a uniform temperature of 375 degrees Fahrenheit. It features pushbutton controls for three timing cycles for different instrument loads, a six-minute cycle for standard unpackaged instruments, eight minutes for certain specialized dental/medical instruments and 12 minutes for packaged instruments which can then be stored in a drawer in sterile condition. System will stay at 375 degrees all day. Continuous operation is not expensive because of the sterilizer's very low power requirements.

  14. New disinfection and sterilization methods.

    PubMed Central

    Rutala, W. A.; Weber, D. J.

    2001-01-01

    New disinfection methods include a persistent antimicrobial coating that can be applied to inanimate and animate objects (Surfacine), a high-level disinfectant with reduced exposure time (ortho-phthalaldehyde), and an antimicrobial agent that can be applied to animate and inanimate objects (superoxidized water). New sterilization methods include a chemical sterilization process for endoscopes that integrates cleaning (Endoclens), a rapid (4-hour) readout biological indicator for ethylene oxide sterilization (Attest), and a hydrogen peroxide plasma sterilizer that has a shorter cycle time and improved efficacy (Sterrad 50). PMID:11294738

  15. Nanoscale topographic changes on sterilized glass surfaces affect cell adhesion and spreading.

    PubMed

    Wittenburg, Gretel; Lauer, Günter; Oswald, Steffen; Labudde, Dirk; Franz, Clemens M

    2014-08-01

    Producing sterile glass surfaces is of great importance for a wide range of laboratory and medical applications, including in vitro cell culture and tissue engineering. However, sterilization may change the surface properties of glass and thereby affect its use for medical applications, for instance as a substrate for culturing cells. To investigate potential effects of sterilization on glass surface topography, borosilicate glass coverslips were left untreated or subjected to several common sterilization procedures, including low-temperature plasma gas, gamma irradiation and steam. Imaging by atomic force microscopy demonstrated that the surface of untreated borosilicate coverslips features a complex landscape of microislands ranging from 1000 to 3000 nm in diameter and 1 to 3 nm in height. Steam treatment completely removes these microislands, producing a nanosmooth glass surface. In contrast, plasma treatment partially degrades the microisland structure, while gamma irradiation has no effect on microisland topography. To test for possible effects of the nanotopographic structures on cell adhesion, human gingival fibroblasts were seeded on untreated or sterilized glass surfaces. Analyzing fibroblast adhesion 3, 6, and 24 h after cell seeding revealed significant differences in cell attachment and spreading depending on the sterilization method applied. Furthermore, single-cell force spectroscopy revealed a connection between the nanotopographic landscape of glass and the formation of cellular adhesion forces, indicating that fibroblasts generally adhere weakly to nanosmooth but strongly to nanorough glass surfaces. Nanotopographic changes induced by different sterilization methods may therefore need to be considered when preparing sterile glass surfaces for cell culture or biomedical applications. PMID:24027204

  16. Rare gas flow structuration in plasma jet experiments

    NASA Astrophysics Data System (ADS)

    Robert, E.; Sarron, V.; Darny, T.; Riès, D.; Dozias, S.; Fontane, J.; Joly, L.; Pouvesle, J.-M.

    2014-02-01

    Modifications of rare gas flow by plasma generated with a plasma gun (PG) are evidenced through simultaneous time-resolved ICCD imaging and schlieren visualization. The geometrical features of the capillary inside which plasma propagates before in-air expansion, the pulse repetition rate and the presence of a metallic target are playing a key role on the rare gas flow at the outlet of the capillary when the plasma is switched on. In addition to the previously reported upstream offset of the laminar to turbulent transition, we document the reverse action leading to the generation of long plumes at moderate gas flow rates together with the channeling of helium flow under various discharge conditions. For higher gas flow rates, in the l min-1 range, time-resolved diagnostics performed during the first tens of ms after the PG is turned on, evidence that the plasma plume does not start expanding in a laminar neutral gas flow. Instead, plasma ignition leads to a gradual laminar-like flow build-up inside which the plasma plume is generated. The impact of such phenomena for gas delivery on targets mimicking biological samples is emphasized, as well as their consequences on the production and diagnostics of reactive species.

  17. The effect of sterilization on silk fibroin biomaterial properties.

    PubMed

    Rnjak-Kovacina, Jelena; DesRochers, Teresa M; Burke, Kelly A; Kaplan, David L

    2015-06-01

    The effects of common sterilization techniques on the physical and biological properties of lyophilized silk fibroin sponges are described. Sterile silk fibroin sponges were cast using a pre-sterilized silk fibroin solution under aseptic conditions or post-sterilized via autoclaving, ? radiation, dry heat, exposure to ethylene oxide, or hydrogen peroxide gas plasma. Low average molecular weight and low concentration silk fibroin solutions could be sterilized via autoclaving or filtration without significant loses of protein. However, autoclaving reduced the molecular weight distribution of the silk fibroin protein solution, and silk fibroin sponges cast from autoclaved silk fibroin were significantly stiffer compared to sponges cast from unsterilized or filtered silk fibroin. When silk fibroin sponges were sterilized post-casting, autoclaving increased scaffold stiffness, while decreasing scaffold degradation rate in vitro. In contrast, ? irradiation accelerated scaffold degradation rate. Exposure to ethylene oxide significantly decreased cell proliferation rate on silk fibroin sponges, which was rescued by leaching ethylene oxide into PBS prior to cell seeding. PMID:25761231

  18. Study of a cumulative gas phenomenon in plasma focus discharge

    Microsoft Academic Search

    H. M. Soliman; T. M. Allam; S. T. Abd El-Latif

    2009-01-01

    A cumulative phenomenon of nitrogen gas at a pressure of 3.3 torr in a 1.2 kJ coaxial plasma focus discharge device was investigated experimentally. Variations of nitrogen gas density in the axial phase along the inter-electrode region were estimated experimentally from the plasma current sheath (PCS) dynamics in terms of its velocity, acceleration as well as axial magnetic force data. An inclination

  19. Nonlocal electron kinetics in collisional gas discharge plasmas

    Microsoft Academic Search

    Vladimir I. Kolobov; Valery A. Godyak

    1995-01-01

    Nonlocal phenomena in electron kinetics of collisional gas discharge plasmas, their kinetic treatment by a nonlocal approach, and relevant experimental results are reviewed in this paper. Using the traditional two-term approximation for the electron distribution function, a general method to analyze electron kinetics in nonuniform plasmas in DC and RF fields for atomic gases is presented for the nonlocal case,

  20. NUCLEAR GENERATED PLASMAS IN NOBLE GAS THERMIONIC CONVERTERS

    Microsoft Academic Search

    F. E. Jamerson; R. H. Jr. Abrams; C. B. Leffert; R. Silver

    1963-01-01

    The generation of a plasma by fission fragment ionization in noble gas ; thermionic converters was investigated in a series of inpile experiments at the ; University of Michigan reactor. The plasma generated in Ne: Ar (1000: 1) at a ; pressure of 20 mm Hg was investigated in a plane parallel diode with electrically ; heated emitter and collector

  1. Corona discharge plasma reactor for decontamination

    Microsoft Academic Search

    J. G. Birmingham; P. M. Irving

    1998-01-01

    Summary form only given. The feasibility of using a gas phase corona plasma to sterilize objects from toxic battlefield, medical, and industrial environments was assessed. Plasma chemical processes can be highly effective in promoting oxidation, enhancing molecular dissociation, or producing free radicals to enhance chemical reaction. Until recently, plasma processes were applied in either the high temperature environment of arc

  2. 21 CFR 610.12 - Sterility.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...require sterility testing for Whole Blood, Cryoprecipitated Antihemophilic Factor, Platelets, Red Blood Cells, Plasma, Source Plasma, Smallpox Vaccine, Reagent Red Blood Cells, Anti-Human Globulin, and Blood Grouping Reagents....

  3. Momentum Model of Gas Jet Penetration in Plasma

    Microsoft Academic Search

    P. B. Parks

    2005-01-01

    The lack of penetration of supersonic gas jets used in recent disruption mitigation experiments is explained. In the model [1], a cold, thin, plasma halo forms over the surface of the jet, shielding the neutral gas interior. The magnetic field inside the jet is slightly less than the field outside as a result of the balance between sideways advection of

  4. Formation of laser plasma channels in a stationary gas

    SciTech Connect

    Dunaevsky, A.; Goltsov, A.; Greenberg, J.; Valeo, E.; Fisch, N.J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540 (United States); Troitsk Institute of Innovative and Thermonuclear Research (TRINITI), Troitsk 142190 (Russian Federation); School of Engineering and Applied Science, Department of MAE, Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

    2006-04-15

    Plasma channels with nonuniformity of about {+-}3.5% have been produced by a 0.3 J, 100 ps laser pulses in a nonflowing gas, contained in a cylindrical chamber. The laser beam passed through the chamber along its axis via pinholes in the chamber walls. Plasma channels with an electron density in the range of 10{sup 18}-10{sup 19} cm{sup -3} were formed in pure He, N{sub 2}, Ar, and Xe. A uniform channel forms in an optimal pressure range at a certain time delay, depending on the gas molecular weight. The interaction of the laser beam with the gas leaking out of the chamber through the pinholes was not significant. However, the formation of the ablative plasma on the walls of pinholes by the wings of radial profile of the laser beam plays an important role in the plasma channel formation and its uniformity. A low-current glow discharge initiated in the chamber improves the uniformity of the plasma channel slightly, while a high-current arc discharge leads to overdense plasma near the front pinhole and further refraction of the laser beam. These results indicate the potential for using nonflowing gas targets to create uniform plasma channels.

  5. Electron energy distribution function control in gas discharge plasmas

    SciTech Connect

    Godyak, V. A. [Electrical Engineering and Computer Science Department, University of Michigan, Ann Arbor, Michigan 48109, USA and RF Plasma Consulting, Brookline, Massachusetts (United States)] [Electrical Engineering and Computer Science Department, University of Michigan, Ann Arbor, Michigan 48109, USA and RF Plasma Consulting, Brookline, Massachusetts (United States)

    2013-10-15

    The formation of the electron energy distribution function (EEDF) and electron temperature in low temperature gas discharge plasmas is analyzed in frames of local and non-local electron kinetics. It is shown, that contrary to the local case, typical for plasma in uniform electric field, there is the possibility for EEDF modification, at the condition of non-local electron kinetics in strongly non-uniform electric fields. Such conditions “naturally” occur in some self-organized steady state dc and rf discharge plasmas, and they suggest the variety of artificial methods for EEDF modification. EEDF modification and electron temperature control in non-equilibrium conditions occurring naturally and those stimulated by different kinds of plasma disturbances are illustrated with numerous experiments. The necessary conditions for EEDF modification in gas discharge plasmas are formulated.

  6. ETHYLENE OXIDE CONTROL TECHNOLOGY DEVELOPMENT FOR HOSPITAL STERILIZERS

    EPA Science Inventory

    The report discusses the development of ethylene oxide (EO) control technology for hospital sterilizers. Hospitals sterilize heat-sensitive items in gas sterilizers that use a mixture of EO (12 wt %) and a chlorofluorocarbon (CFC) (88 wt %). The active sterilizing agent is EO. Th...

  7. Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

    SciTech Connect

    A. Dunaevsky; N.J. Fisch

    2004-03-08

    Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

  8. Microwave Plasma Sources for Gas Processing

    NASA Astrophysics Data System (ADS)

    Mizeraczyk, J.; Jasinski, M.; Dors, M.; Zakrzewski, Z.

    2008-03-01

    In this paper atmospheric pressure microwave discharge methods and devices used for producing the non-thermal plasmas for processing of gases are presented. The main part of the paper concerns the microwave plasma sources (MPSs) for environmental protection applications. A few types of the MPSs, i.e. waveguide-based surface wave sustained MPS, coaxial-line-based and waveguide-based nozzle-type MPSs, waveguide-based nozzleless cylinder-type MPS and MPS for microdischarges are presented. Also, results of the laboratory experiments on the plasma processing of several highly-concentrated (up to several tens percent) volatile organic compounds (VOCs), including Freon-type refrigerants, in the moderate (200-400 W) waveguide-based nozzle-type MPS (2.45 GHz) are presented. The results showed that the microwave discharge plasma fully decomposed the VOCs at relatively low energy cost. The energy efficiency of VOCs decomposition reached 1000 g/kWh. This suggests that the microwave discharge plasma can be a useful tool for environmental protection applications. In this paper also results of the use of the waveguide-based nozzleless cylinder-type MPS to methane reforming into hydrogen are presented.

  9. Carbon dioxide as working gas for laboratory plasmas

    NASA Technical Reports Server (NTRS)

    Kist, R.

    1976-01-01

    Measurements with a RF probe, retarding potential analyzer and mass spectrometer in a laboratory plasma tank were performed using the gases CO2, N2, A and He in order to compare their properties as working gases for laboratory plasma production. The overall result of that CO2 leads to higher plasma densities at lower neutral-gas pressures as well as to a larger Maxwellian component of the electron population, while the electron temperature is lower than that when N2, A and He are used.

  10. Plasma Impurity Estimations Using Residual Gas Analysis at MCX

    NASA Astrophysics Data System (ADS)

    Romero-Talamas, C. A.; Young, W. C.; Taylor, G.; Ellis, R. F.; Hassam, A. B.; Teodorescu, C.

    2009-11-01

    A methodology to characterize impurity concentrations created during plasma shots is being tested at the Maryland Centrifugal Experiment (MCX) [R.F. Ellis, et al., Phys. Plasmas 12, 055704 (2005)]. The methodology consists of measurements every 2 seconds of mass spectra with a residual gas analyzer (RGA) before, during, and after plasma shots (10 ms), and fitting the measured signals to the heat load equation for a fixed volume and time varying pressure. An extrapolation of this equation is then made to the plasma time in order to find the maximum pressure, which is otherwise too high and short-lived for reliable RGA measurements. Ratios of hydrogen or helium to impurities are then estimated and used in MCX theory models, in tracking effects of new instruments installed in the MCX vessel, and in assessing the efficacy of cleaning campaigns on plasma shots.

  11. Plasma reforming and partial oxidation of hydrocarbon fuel vapor to produce synthesis gas and/or hydrogen gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2003-08-19

    Methods and systems for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  12. Plasma Reforming And Partial Oxidation Of Hydrocarbon Fuel Vapor To Produce Synthesis Gas And/Or Hydrogen Gas

    DOEpatents

    Kong, Peter C. (Idaho Falls, ID); Detering, Brent A. (Idaho Falls, ID)

    2004-10-19

    Methods and systems are disclosed for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  13. Observations of thermal creep gas flow and dust-density waves in dusty plasma experiments

    Microsoft Academic Search

    Timothy Mcguire Flanagan

    2010-01-01

    In laboratory experiments, I study strongly-coupled dusty plasma levitated in a glow-discharge plasma. Dusty plasma is an arrangement of small dust particles in a plasma background of electrons, ions, and neutral gas. The dust particles are negatively charged because they collect electrons and ions from the background plasma. Depending on the experimental setup, the plasma's electric field can help to

  14. System and method of applying energetic ions for sterilization

    DOEpatents

    Schmidt, John A.

    2003-12-23

    A method of sterilization of a container is provided whereby a cold plasma is caused to be disposed near a surface to be sterilized, and the cold plasma is then subjected to a pulsed voltage differential for producing energized ions in the plasma. Those energized ions then operate to achieve spore destruction on the surface to be sterilized. Further, a system for sterilization of a container which includes a conductive or non-conductive container, a cold plasma in proximity to the container, and a high voltage source for delivering a pulsed voltage differential between an electrode and the container and across the cold plasma, is provided.

  15. Gas laser with dual plasma mixing

    DOEpatents

    Pinnaduwage, L.A.

    1999-04-06

    A gas laser includes an enclosure forming a first chamber, a second chamber and a lasing chamber which communicates through a first opening to the first chamber and through a second opening to the second chamber. The lasing chamber has a pair of reflectors defining a Fabry-Perot cavity. Separate inlets enable different gases to be introduced into the first and second chambers. A first cathode within the first chamber is provided to produce positive ions which travel into the lasing chamber and a second cathode of a pin-hollow type within the second chamber is provided to produce negative ions which travel into the lasing chamber. A third inlet introduces a molecular gas into the lasing chamber, where the molecular gas becomes excited by the positive and negative ions and emits light which lases in the Fabry-Perot cavity. 2 figs.

  16. Gas laser with dual plasma mixing

    DOEpatents

    Pinnaduwage, Lal A. (Knoxville, TN)

    1999-01-01

    A gas laser includes an enclosure forming a first chamber, a second chamber and a lasing chamber which communicates through a first opening to the first chamber and through a second opening to the second chamber. The lasing chamber has a pair of reflectors defining a Fabry-Perot cavity. Separate inlets enable different gases to be introduced into the first and second chambers. A first cathode within the first chamber is provided to produce positive ions which travel into the lasing chamber and a second cathode of a pin-hollow type within the second chamber is provided to produce negative ions which travel into the lasing chamber. A third inlet introduces a molecular gas into the lasing chamber, where the molecular gas becomes excited by the positive and negative ions and emits light which lases in the Fabry-Perot cavity.

  17. Neutral gas plasma interactions and critical ionization velocity phenomena

    Microsoft Academic Search

    K. Papadopoulos

    1983-01-01

    The interplay of collisional and collisionless phenomena in the interaction of a magnetoplasma streaming through neutral gas produces some of the most fascinating plasma physics phenomena. A key notion controlling such interactions is the existence of a critical velocity (U sub c) effect postulated in an ad hoc fashion by Alfven, in his model of the formation of the solar

  18. Hydrogen Diluted Methane Plasma Gas-Substrate Metal Interaction

    NASA Astrophysics Data System (ADS)

    Okuno, Kimio; Lui, Lai; Furumoto, Takashi

    2008-05-01

    The interaction between hydrogen-diluted methane plasma gas and substrate metal has been investigated to evaluate interfacial phenomena in the heteroepitaxial growth and initial-stage growth of diamond by combing chemical vapor deposition and field ion microscopy (CVD-FIM). The interaction with plasma gas was evaluated from the behavior of the Fowler-Nordheim plot and field ion images, after plasma gas was exposed to a tungsten needle specimen (W tip) at methane contents CH4/H2 of 1-3%. The plasma gas-W tip surface interaction was very intensive, and thick carbonaceous layers in the amorphous state were formed with a depth of several tenths atomic layers on the top surface of a W tip. Some condensed carbon clusters consisting of several carbon atoms emerged on the interfacial carbonaceous mixed layers. The energetic carbon atom was very cohesive, and the condensed carbon clusters corresponded to prenucleation or prediamond states prior to bulk diamond growth. The behavior of the field emission characteristics originating from the condensed clusters consisting of carbon atoms was also discussed.

  19. Mathematical model of gas plasma applied to chronic wounds

    SciTech Connect

    Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P. [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China)] [State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Zhang, Y. T. [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China)] [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China)

    2013-11-15

    Chronic wounds are a major burden for worldwide health care systems, and patients suffer pain and discomfort from this type of wound. Recently gas plasmas have been shown to safely speed chronic wounds healing. In this paper, we develop a deterministic mathematical model formulated by eight-species reaction-diffusion equations, and use it to analyze the plasma treatment process. The model follows spatial and temporal concentration within the wound of oxygen, chemoattractants, capillary sprouts, blood vessels, fibroblasts, extracellular matrix material, nitric oxide (NO), and inflammatory cell. Two effects of plasma, increasing NO concentration and reducing bacteria load, are considered in this model. The plasma treatment decreases the complete healing time from 25 days (normal wound healing) to 17 days, and the contributions of increasing NO concentration and reducing bacteria load are about 1/4 and 3/4, respectively. Increasing plasma treatment frequency from twice to three times per day accelerates healing process. Finally, the response of chronic wounds of different etiologies to treatment with gas plasmas is analyzed.

  20. Application of non-thermal plasma on gas cleansing

    NASA Astrophysics Data System (ADS)

    Pacheco, M.; Pacheco, J.; Moreno, H.; Santana, A.

    2008-10-01

    Non-thermal plasma technologies are an interesting complement or alternative, for some conventional systems used for gas pollution control (i.e. wet scrubbers and catalytic converters) because they are able to remove simultaneously several gas pollutants, with quite good efficiency at a relatively low-energy consumption. In this work, a dielectric barrier discharge was used to remove nitric oxides (NOx) and sulfur dioxide (SO2) from a mixture of air and water vapor. A chemical model was developed to obtain a toxic gas removal mechanism and to observe the behavior of the species in the plasma. The influence of water vapor addition on the toxic gases removal efficiency is also investigated. Several experimental parameters such as power, frequency, initial concentration of NOx and SO2 were tested and analyzed. Results of numerical simulation demonstrated good agreement with experimental data of the removal process achieving about 95% of efficiency removal of toxic gases studied.

  1. 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.

  2. Radiochemical sterilization and its use for sutures

    Microsoft Academic Search

    S. W. Shalaby; Y. Doyle; B. L. Anneaux; K. A. Carpenter; F. R. Schiretz

    2003-01-01

    Radiochemical sterilization (RC-S) represents a novel approach to medical device sterilization. It is a hybrid process encompassing the attributes of chemical and high-energy radiation sterilization without the drawbacks associated with the use of the parent processes. It entails the use of a 5-7.5 kGy of gamma radiation and a polyformaldehyde insert capable of a radiolytic-controlled release of formaldehyde gas in

  3. Radiochemical sterilization and its use for sutures

    Microsoft Academic Search

    S. W. Shalaby; Y. Doyle; B. L. Anneaux; K. A. Carpenter; F. R. Schiretz

    2003-01-01

    Radiochemical sterilization (RC-S) represents a novel approach to medical device sterilization. It is a hybrid process encompassing the attributes of chemical and high-energy radiation sterilization without the drawbacks associated with the use of the parent processes. It entails the use of a 5–7.5 kGy of ? radiation and a polyformaldehyde insert capable of a radiolytic-controlled release of formaldehyde gas in

  4. Energetic binary collisions in rare gas plasmas

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.

    1979-01-01

    Calculations have been made of cross sections for energy and momentum transfer in binary collisions between like pairs of Ar, Kr, and Xe atoms in the energy range from about 1 to 1000 eV. These calculations were made using a classical model with pair interaction potentials for the rare gases developed from experimental sources, e.g., investigations of specific heats, viscosities, solid-state parameters, and scattering data. Cross sections in this energy range have not been available. The cross sections exhibit a rapid decrease from accepted values at thermal energies as the interaction energy increases. This behavior can be used to understand directed beam propagation limits as well as particle propagation within a plasma. Experimental data have also been fit to a theoretical expression for the Ar resonance charge exchange cross section over the same energy range.

  5. Formation of laser plasma channels in a stationary gas

    E-print Network

    Dunaevsky, A; Greenberg, J; Suckewer, S; Valeo, E; Fisch, N J

    2005-01-01

    The formation of plasma channels with nonuniformity of about +- 3.5% has been demonstrated. The channels had a density of 1.2x10^19 cm-3 with a radius of 15 um and with length >= 2.5 mm. The channels were formed by 0.3 J, 100 ps laser pulses in a nonflowing gas, contained in a cylindrical chamber. The laser beam passed through the chamber along its axis via pinholes in the chamber walls. A plasma channel with an electron density on the order of 10^18 - 10^19 cm-3 was formed in pure He, N2, Ar, and Xe. A uniform channel forms at proper time delays and in optimal pressure ranges, which depend on the sort of gas. The influence of the interaction of the laser beam with the gas leaking out of the chamber through the pinholes was found insignificant. However, the formation of an ablative plasma on the walls of the pinholes by the wings of the radial profile of the laser beam plays an important role in the plasma channel formation and its uniformity. A low current glow discharge initiated in the chamber slightly imp...

  6. Plasma remediation of gas streams contaminated by trichloroethylene

    SciTech Connect

    Evans, D.; Kushner, M.K. [Univ. of Illinois, Urbana, IL (United States); Rosocha, L.A. [Los Alamos National Lab., NM (United States)

    1992-12-01

    There is increasing interest in using plasmas to cleanse gas streams of toxic gases and for toxic waste remediation. Silent discharges (or dielectric barrier discharges) are attractive in this regard because they operate stably at high power deposition and atmospheric pressure. The authors have experimentally and computationally investigated the removal of trichloroethylene (C{sub 2}HCl{sub 3}) or TCE from Ar/O{sub 2}/H{sub 2}O gas streams using a silent discharge. Experimental results will be discussed where TCE is removed from the gas stream (1000 ppm reduced to < 1 ppm) with moderate energy deposition (10s mJ-cm{sup {minus}3}). The desired reaction products are CO{sub 2} and UC1. The plasma removal of TCE, however, directly produces undesirable products such as CHOCl and COCl{sub 2} (phosgene). These products can also be oxidized and removed from the gas stream by further increasing power deposition beyond that required for removal of TCE. Reaction mechanisms will be discussed with results from a plasma chemistry computer model.

  7. Transport in a field aligned magnetized plasma/neutral gas boundary: the end of the plasma

    NASA Astrophysics Data System (ADS)

    Cooper, Christopher Michael

    The objective of this dissertation is to characterize the physics of a boundary layer between a magnetized plasma and a neutral gas along the direction of a confining magnetic field. A series of experiments are performed at the Enormous Toroidal Plasma Device (ETPD) at UCLA to study this field aligned Neutral Boundary Layer (NBL) at the end of the plasma. A Lanthanum Hexaboride (LaB6) cathode and semi-transparent anode creates a magnetized, current-free helium plasma which terminates on a neutral helium gas without touching any walls. Probes are inserted into the plasma to measure the basic plasma parameters and study the transport in the NBL. The experiment is performed in the weakly ionized limit where the plasma density (ne) is much less than the neutral density (nn) such that ne/nn < 5%. The NBL is characterized by a field-aligned electric field which begins at the point where the plasma pressure equilibrates with the neutral gas pressure. Beyond the pressure equilibration point the electrons and ions lose their momentum by collisions with the neutral gas and come to rest. An electric field is established self consistently to maintain a current-free termination through equilibration of the different species' stopping rates in the neutral gas. The electric field resembles a collisional quasineutral sheath with a length 10 times the electron-ion collision length, 100 times the neutral collision length, and 10,000 times the Debye length. Collisions with the neutral gas dominate the losses in the system. The measured plasma density loss rates are above the classical cross-field current-free ambipolar rate, but below the anomalous Bohm diffusion rate. The electron temperature is below the ionization threshold of the gas, 2.2 eV in helium. The ions are in thermal equilibrium with the neutral gas. A generalized theory of plasma termination in a Neutral Boundary Layer is applied to this case using a two-fluid, current-free, weakly ionized transport model. The electron and ion momentum equations along the field are combined in a generalized Ohm's law which predicts the axial electric field required to maintain a current-free termination. The pressure balance criteria for termination and the predicted electric field are confirmed over a scaling of plasma parameters. The experiment and the model are relevant for studying NBLs in other systems, such as the atmospheric termination of the aurora or detached gaseous divertors. A steady state modified ambipolar system is measured in the ETPD NBL. The drift speeds associated with these currents are a small fraction of the plasma flow speeds and the problem is treated as a perturbation to the termination model. The current-free condition on the model is relaxed to explain the presence of the divergence free current.

  8. Classical transport equations for burning gas-metal plasmas

    NASA Astrophysics Data System (ADS)

    Molvig, Kim; Simakov, Andrei N.; Vold, Erik L.

    2014-09-01

    Thermonuclear inertial confinement fusion plasmas confined by a heavy metal shell may be subject to the mixing of metal into the gas with a resulting degradation of fusion yield. Classical plasma diffusion driven by a number of gradients can provide a physical mechanism to produce atomic mix, possibly in concert with complex hydrodynamic structures and/or turbulence. This paper gives a derivation of the complete dissipative plasma hydrodynamics equations from kinetic theory, for a binary ionic mixture plasma consisting of electrons, e, a light (hydrogenic gas) ion species, i, and a heavy, high ZI plasma metal species, I. A single mean ionization state for the heavy metal, ZI, is assumed to be provided by some independent thermodynamic model of the heavy metal Z I = Z I ( n i , n I , T e ). The kinetic equations are solved by a generalized Chapman-Enskog expansion that assumes small Knudsen numbers for all species: N K e ? ? e / L ? 1 , N K i ? ? i / L ? 1. The small electron to ion mass ratio, m e / m i ? 1, is utilized to account for electron-ion temperature separation, T e ? T i, and to decouple the electron and ion transport coefficient calculations. This produces a well ordered perturbation theory for the electrons, resulting in the well known "Spitzer" problem of Spitzer and collaborators and solved independently by Braginskii. The formulation in this paper makes clear the inherent symmetry of the transport and gives an analytic solution for all values of the effective charge Z eff, including Z eff < 1. The electron problem also determines the ambipolar electric field and the "thermal forces" on both ion species that are needed for the ion kinetic solution. The ion transport problem makes use of the small mass ratio between ion species, m i / m I ? 1, to identify an "ion Spitzer problem" that is mathematically identical to that for the electrons but with different thermodynamic forces. The ionic scattering parameter, ? I ? n I Z I 2 / n i, replaces the Z eff of the electron problem, but has an extended domain, 0? ? I < ?, to cover all mixture fractions from the pure gas to the pure metal plasma. The extension of the Spitzer problem to include this extended domain is given in this work. The resulting transport equations for the binary gas-metal plasma mixture are complete and accurate through second order. All transport coefficients are provided in analytic form.

  9. Laser-plasma interactions in large gas-filled hohlraums

    SciTech Connect

    Turner, R.E.; Powers, L.V.; Berger, R.L. [and others

    1996-06-01

    Indirect-drive targets planned for the National Ignition Facility (NIF) laser consist of spherical fuel capsules enclosed in cylindrical Au hohlraums. Laser beams, arranged in cylindrical rings, heat the inside of the Au wall to produce x rays that in turn heat and implode the capsule to produce fusion conditions in the fuel. Detailed calculations show that adequate implosion symmetry can be maintained by filling the hohlraum interior with low-density, low-Z gases. The plasma produced from the heated gas provides sufficient pressure to keep the radiating Au surface from expanding excessively. As the laser heats this gas, the gas becomes a relatively uniform plasma with small gradients in velocity and density. Such long-scale-length plasmas can be ideal mediums for stimulated Brillouin Scattering (SBS). SBS can reflect a large fraction of the incident laser light before it is absorbed by the hohlraum; therefore, it is undesirable in an inertial confinement fusion target. To examine the importance of SBS in NIF targets, the authors used Nova to measure SBS from hohlraums with plasma conditions similar to those predicted for high-gain NIF targets. The plasmas differ from the more familiar exploding foil or solid targets as follows: they are hot (3 keV); they have high electron densities (n{sub e}=10{sup 21}cm{sup {minus}3}); and they are nearly stationary, confined within an Au cylinder, and uniform over large distances (>2 mm). These hohlraums have <3% peak SBS backscatter for an interaction beam with intensities of 1-4 x 10{sup 15} W/cm{sup 2}, a laser wavelength of 0.351{micro}m, f/4 or f/8 focusing optics, and a variety of beam smoothing implementations. Based on these conditions the authors conclude that SBS does not appear to be a problem for NIF targets.

  10. Modeling and Data Needs of Atmospheric Pressure Gas Plasma and Biomaterial Interaction

    SciTech Connect

    Sakiyama, Yukinori; Graves, David B. [Department of Chemical Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States)

    2009-05-02

    Non-thermal atmospheric pressure plasmas have received considerable attention recently. One promising application of non-thermal plasma devices appears to be biomaterial and biomedical treatment. Various biological and medical effects of non-thermal plasmas have been observed by a variety of investigators, including bacteria sterilization, cell apoptosis, and blood coagulation, among others. The mechanisms of the plasma-biomaterial interaction are however only poorly understood. A central scientific challenge is therefore how to answer the question: 'What plasma-generated agents are responsible for the observed biological effects?' Our modeling efforts are motivated by this question. In this paper, we review our modeling results of the plasma needle discharge. Then, we address data needs for further modeling and understanding of plasma-biomaterial interaction.

  11. Kinetics of low-temperature plasma and gas lasers

    Microsoft Academic Search

    A. A. Komar

    1984-01-01

    The papers contained in this volume provide an overview of experimental and theoretical research of the processes taking place in low-temperature plasmas and active media of gas lasers. Topics discussed include a study of the high-current low-pressure discharge and kinetics of processes occurring in the continuous-wave argon ion laser; collisional and radiative processes involving highly excited states of atoms and

  12. Neutral gas plasma interactions and critical ionization velocity phenomena

    NASA Astrophysics Data System (ADS)

    Papadopoulos, K.

    1983-11-01

    The interplay of collisional and collisionless phenomena in the interaction of a magnetoplasma streaming through neutral gas produces some of the most fascinating plasma physics phenomena. A key notion controlling such interactions is the existence of a critical velocity (U sub c) effect postulated in an ad hoc fashion by Alfven, in his model of the formation of the solar system. According to Alfven's postulate, whenever the relative velocity between a neutral gas and a streaming magnetoplasma exceeds a value U sub c identical with Square root of (2Esub i/M), where E sub i is the ionization energy and M the mass of the neutral atoms, rapid ionization and anomalous momentum coupling occurs. Guided by recent laboratory and space experiments and plasma physics theory we present the basic plasma physics underlying the interaction. This is followed by a discussion of its relevance to the formation of the solar system and cometary tails, its controlling effect on plasma centrifuges and homopolar generators, and the fascinating possibility that critical velocity phenomena are controlling the space shuttle environment, transforming it into an artificial comet.

  13. Design and Preliminary Performance Testing of Electronegative Gas Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Liu, Thomas M.; Schloeder, Natalie R.; Walker, Mitchell L. R.; Polzin, Kurt A.; Dankanich, John W.; Aanesland, Ane

    2014-01-01

    In classical gridded electrostatic ion thrusters, positively charged ions are generated from a plasma discharge of noble gas propellant and accelerated to provide thrust. To maintain overall charge balance on the propulsion system, a separate electron source is required to neutralize the ion beam as it exits the thruster. However, if high-electronegativity propellant gases (e.g., sulfur hexafluoride) are instead used, a plasma discharge can result consisting of both positively and negatively charged ions. Extracting such electronegative plasma species for thrust generation (e.g., with time-varying, bipolar ion optics) would eliminate the need for a separate neutralizer cathode subsystem. In addition for thrusters utilizing a RF plasma discharge, further simplification of the ion thruster power system may be possible by also using the RF power supply to bias the ion optics. Recently, the PEGASES (Plasma propulsion with Electronegative gases) thruster prototype successfully demonstrated proof-of-concept operations in alternatively accelerating positively and negatively charged ions from a RF discharge of a mixture of argon and sulfur hexafluoride.i In collaboration with NASA Marshall Space Flight Center (MSFC), the Georgia Institute of Technology High-Power Electric Propulsion Laboratory (HPEPL) is applying the lessons learned from PEGASES design and testing to develop a new thruster prototype. This prototype will incorporate design improvements and undergo gridless operational testing and diagnostics checkout at HPEPL in April 2014. Performance mapping with ion optics will be conducted at NASA MSFC starting in May 2014. The proposed paper discusses the design and preliminary performance testing of this electronegative gas plasma thruster prototype.

  14. Particle Dynamics in Neutral-Gas Confined Laser-Produced Plasmas

    Microsoft Academic Search

    Yong W. Kim

    2001-01-01

    Laser-produced plasma from a metallic target can be confined to higher plasma densities by immersing the target in an inert gas medium at increasingly high density. The plasma becomes Rayleigh-Taylor unstable, however, when the mass density of the neutral gas exceeds the plasma mass density substantially.[1] A new plasma diagnostic method is developed to help examine the early time development

  15. Control of plasma parameters by using noble gas admixtures

    SciTech Connect

    Taylor, Kurt J.; Yun, Seokmin; Tynan, George R. [Department of Mechanical and Aerospace Engineering, and Center for Energy Research, University of California, San Diego, California 92093-0417 (United States)

    2004-09-01

    Electron temperature and density in pure He, Ar, and Xe plasmas are estimated by zero-dimensional particle and power balance equations and measured by a Langmuir probe. Both of the modeling and experimental results show that the He (Xe) plasma has the highest (lowest) electron temperature and lowest (highest) electron density for a given fill pressure and source power. We find that the electron temperature is weakly dependent on the rf power, and thus the electron density can be controlled using the rf power. The electron temperature and density are also modeled and measured in mixtures of two noble gas species. We find that the electron temperature can be controlled by altering the composition of the noble gas mixture. Thus modulation of noble gas admixture ratios and rf power allows the electron density and temperature to be controlled independently. This independent control is shown to maintained with the addition of up to 20% partial pressure of oxygen, suggesting binary noble gas admixtures may provide additional control of dissociation kinetics.

  16. Plasma formation using a capillary discharge in water and its application to the sterilization of E. coli

    SciTech Connect

    Hong, Yong Cheol; Park, Hyun Jae; Lee, Bong Ju [Convergence Plasma Research Center, National Fusion Research Institute, 113 Gwahangno, Yuseong-Gu, Daejeon 305-333 (Korea, Republic of); Kang, Won-Seok [Department of Molecular Science and Technology, Ajou University, San 5, Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of); Uhm, Han Sup [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Gu, Seoul 139-701 (Korea, Republic of)

    2010-05-15

    An underwater electrical discharge in a narrow dielectric capillary provides the details of the evolution of microbubbles to plasma as formed by a tungsten electrode inserted in the capillary. An increase in the applied voltage forms microbubbles after water fills the capillary. A further increase in the voltage generates a surface discharge through the boundary of the bubble, elongating the bubble shape, and eventually forming plasma by electrical breakdown. This produces atomic oxygen, atomic hydrogen, and hydroxyl radicals from dissociation of water vapor. Also, a bactericidal test in normal saline solution showed that more than 99.6% of the bacterial cells were killed within 8 s, resulting from chlorine-containing species, in particular hypochlorous acid as a major bactericidal agent.

  17. Determination of Compounds Inhibiting Bacterial Growth in Sterilized Medical Devices

    Microsoft Academic Search

    H. Shintani; E. Suzuki; M. Sakurai

    2003-01-01

    Summary Medical devices must be sterilized before shipping. During sterilization the quality of the medical device must be maintained. Polysulfone (PS) and polycarbonate (PC) are often used as materials for medical devices. It has been observed that compounds inhibiting bacterial growth are produced when PS or PC are sterilized by autoclaving or by use of ozone gas, especially when ozone

  18. Study of Gas and Plasma Conditions in the High Isp VASIMR Thruster

    Microsoft Academic Search

    O. Batishchev; K. Molvig

    2002-01-01

    Internal electrode-free VASIMR thruster [1-3] consists of three major sections: plasma production, plasma heating, and plasma exhaust. In our previous works [6-10] we have performed an extensive study of plasma dynamics in the plasma source. We have developed several models of helicon plasma discharge utilizing hydrogen (deuterium) gas, and analyzed its performance in the experimental set-up [4-5]. In the present

  19. Instability of dusty particle system in gas-discharge plasma

    SciTech Connect

    Filinov, V.S.; Petrov, O.F.; Fortov, V.E.; Molotkov, V.I. [Institute for High Energy Densities, Izhorskaya 13/19, 125412 Moscow (Russian Federation); Khakhaev, A.D.; Podrjadchikov, S.F. [Petrozavodsk state university NOZ 'Plasma', Lenin street 33, Petrozavodsk 185640 (Russian Federation)

    2005-10-31

    An effective anisotropic potential is proposed for the interaction between dust particles in a gas-discharge plasma. In addition to the Coulomb repulsion this potential takes into account attraction due to the spatial positive plasma charge originating from focusing of the ionic fluxes by dusty particles. The time evolution of the dust particle kinetic and potential energies from random initial configurations have been investigated by the Brownian dynamics method. Results of our simulation showed that the attraction between dusty particles can be the main physical reason of formation and decay of classical bound dust particle pairs and many particle complexes with low potential energy, while the kinetic energy (temperature) of unbound dust particles and particle oscillating in bound complexes may increase on three order as observed in experiments.

  20. Propagation of magnetoacoustic surface waves along static plasma slab surrounded by moving plasma and neutral gas

    NASA Astrophysics Data System (ADS)

    Valliammal, R.; Sivaraman, M.; Somasundaram, K.

    2010-11-01

    The existence and propagation of fast and slow magnetoacoustic surface waves (MASW) is investigated in our work by taking a theoretical model of a static plasma slab as the middle layer with a moving plasma region at the top and neutral gas medium as the bottom layer. Applying linear MHD, the dispersion relation is obtained and the propagation of magnetoacoustic surface waves, in the compressional limit for steady flow and for different values of dimensionless wave numbers, is analyzed. Steady flow of plasma along a structured atmosphere may cause enhancement of existing surface modes, disappearance of some modes and generation of new surface wave modes. The possible regions for the propagation of fast and slow surface and body waves for different mass density ratios and magnetic field ratios and with a small flow velocity are studied. Our discussion may help in analyzing more complicated cases.

  1. Supersonic gas jets for laser-plasma experiments.

    PubMed

    Schmid, K; Veisz, L

    2012-05-01

    We present an in-depth analysis of De Laval nozzles, which are ideal for gas jet generation in a wide variety of experiments. Scaling behavior of parameters especially relevant to laser-plasma experiments as jet collimation, sharpness of the jet edges and Mach number of the resulting jet is studied and several scaling laws are given. Special attention is paid to the problem of the generation of microscopic supersonic jets with diameters as small as 150 ?m. In this regime, boundary layers dominate the flow formation and have to be included in the analysis. PMID:22667614

  2. Nucleation and growth of Nb nanoclusters during plasma gas condensation

    SciTech Connect

    Bray, K. R.; Jiao, C. Q. [UES, Inc., 4401 Dayton-Xenia Rd, Dayton, Ohio 45432 (United States)] [UES, Inc., 4401 Dayton-Xenia Rd, Dayton, Ohio 45432 (United States); DeCerbo, J. N. [Air Force Research Laboratory, AFRL/RQQE, 1950 Fifth St., WPAFB, Ohio 45433 (United States)] [Air Force Research Laboratory, AFRL/RQQE, 1950 Fifth St., WPAFB, Ohio 45433 (United States)

    2013-06-21

    Niobium nanoclusters were produced using a plasma gas condensation process. The influence of gas flow rate, aggregation length, and source current on the nanocluster nucleation and growth were analyzed. Nanoclusters with an average diameter from 4 nm to 10 nm were produced. Cluster size and concentration were tuned by controlling the process inputs. The effects of each parameter on the nucleation zone, growth length, and residence time was examined. The parameters do not affect the cluster formation and growth independently; their influence on cluster formation can be either cumulative or competing. Examining the nucleation and growth over a wide combination of parameters provided insight into their interactions and the impact on the growth process. These results provide the opportunity for a broader understanding into the nucleation and growth of nanoclusters and some insights into how process parameters interact during deposition. This knowledge will enhance the ability to create nanoclusters with desired size dispersions.

  3. Plasma polymerization of an ethylene-nitrogen gas mixture

    NASA Technical Reports Server (NTRS)

    Hudis, M.; Wydeven, T.

    1975-01-01

    A procedure has been developed whereby nitrogen can be incorporated into an organic film from an ethylene-nitrogen gas mixture using an internal electrode capacitively coupled radio frequency reactor. The presence of nitrogen has been shown directly by infrared transmittance spectra and electron spectroscopic chemical analysis data, and further indirect evidence was provided by dielectric measurements and by the reverse osmosis properties of the film. Preparation of a nitrogen containing film did not require vapor from an organic nitrogen containing liquid monomer. Some control over the bonding and stoichiometry of the polymer film was provided by the added degree of freedom of the nitrogen partial pressure in the gas mixture. This new parameter strongly affected the dielectric properties of the plasma polymerized film and could affect the reverse osmosis behavior.

  4. Laser ablated copper plasmas in liquid and gas ambient

    SciTech Connect

    Kumar, Bhupesh; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)] [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2013-05-15

    The dynamics of copper ablated plasma plumes generated using laser ablation of copper targets in both liquid (de-ionized water) and gas (air) ambients is reported. Using time and space resolved visible emission spectroscopy (450-650 nm), the plasma plumes parameters are investigated. The electron density (n{sub e}) determined using Stark broadening of the Cu I (3d{sup 10}4d{sup 1} {sup 2}D{sub 3/2}-3d{sup 10}4p{sup 1} {sup 2}P{sub 3/2} at 521.8 nm) line is estimated and compared for both plasma plumes. The electron temperature (T{sub e}) was estimated using the relative line emission intensities of the neutral copper transitions. Field emission scanning electron microscopy and energy dispersive x-ray spectral analysis of the ablated copper surface indicated abundance of spherical nanoparticles in liquid while those in air are amalgamates of irregular shapes. The nanoparticles suspended in the confining liquid form aggregates and exhibit a surface plasmon resonance at ?590 nm.

  5. Modelling penetration and plasma response of a dense neutral gas jet in a post-thermal quenched plasma

    NASA Astrophysics Data System (ADS)

    Parks, P. B.; Wu, W.

    2014-02-01

    This paper is about the dynamics of gas jet injection and propagation into the cold, current quench (CQ) discharge following the thermal quench (TQ) phase of a disruption event. Understanding the processes involved in the interpenetration between a dense, fast-moving supersonic gas jet and a magnetized plasma is fundamental to the solution of the disruption mitigation problem using massive gas injection. An analytical model was developed that provides the penetration depth of the jet in the CQ discharge. The model developed incorporates the injector, the vacuum space between injector and plasma, and the low beta CQ plasma through which the jet penetrates. The radially moving gas stagnates at some point inside the plasma by formation of a ‘bottle shock’, resulting in a certain penetration depth. Consistent with experimental findings, it is shown that high fuelling efficiency >70% and good penetration beyond the q = 2 surface is possible in such plasma discharges, but in normal (unquenched) plasma discharges penetration of dense gas jets will be quite poor. The paper also sheds light on how the external plasma responds to allow interpenetration of perfectly insulating gas jet through a strong magnetic field B2/2?0 ? ?u2. The paper also develops semi-analytical models for the response of the cold, high-current, collision-dominated plasma to the insertion of a dense neutral jet: the propagation of cooling waves out along the magnetic field lines, the heated and ionized surface layer which also expands outwards along the magnetic field lines, and the electrical breakdown of the neutral gas within the jet volume. Although good penetration in the ITER post-TQ discharge can be achieved, the plasma resistivity is only marginally enhanced. This may render repetitive gas inject ineffective, as the concept requires a sizable resistivity enhancement to initiate a current profile contraction, and resulting kink-tearing activity to suppress runaway avalanching.

  6. Experiment on the interaction between a plasma and a neutral gas

    Microsoft Academic Search

    Lars Danielsson

    1970-01-01

    In an experiment where a high velocity plasma stream penetrates a stationary neutral gas cloud in a magnetic field, it is found that the interaction between the plasma and the gas is far more violent than what can be expected from simple atomic interaction theories. The parameters are such that the character of the interaction is collisionless. The observations demonstrate

  7. Tunable Circularly-Polarized Terahertz Radiation from Magnetized Gas Plasma

    E-print Network

    Wang, W -M; Sheng, Z -M; Li, Y -T

    2015-01-01

    It is shown by simulation and theory that circularly or elliptically polarized terahertz radiation can be generated when a static magnetic (B) field is imposed on a gas target along the propagation direction of a two-color laser driver. The radiation frequency is determined by $\\sqrt{\\omega_p^2+{\\omega_c^2}/{4}} + {\\omega_c}/{2}$, where $\\omega_p$ is the plasma frequency and $\\omega_c$ is the electron cyclotron frequency. With the increase of the B field, the radiation changes from a single-cycle broadband waveform to a continuous narrow-band emission. In high B field cases, the radiation strength is proportional to $\\omega_p^2/\\omega_c$. The B field provides a tunability in the radiation frequency, spectrum width, and field strength.

  8. Tunable Circularly Polarized Terahertz Radiation from Magnetized Gas Plasma

    NASA Astrophysics Data System (ADS)

    Wang, W.-M.; Gibbon, P.; Sheng, Z.-M.; Li, Y.-T.

    2015-06-01

    It is shown, by simulation and theory, that circularly or elliptically polarized terahertz radiation can be generated when a static magnetic (B ) field is imposed on a gas target along the propagation direction of a two-color laser driver. The radiation frequency is determined by ?{?p2+?c2/4 }+?c/2 , where ?p is the plasma frequency and ?c is the electron cyclotron frequency. With the increase of the B field, the radiation changes from a single-cycle broadband waveform to a continuous narrow-band emission. In high-B -field cases, the radiation strength is proportional to ?p2/?c . The B field provides a tunability in the radiation frequency, spectrum width, and field strength.

  9. Initial experiments of RF gas plasma source for heavy ionfusion

    SciTech Connect

    Ahle, L.; Hall, R.; Molvik, A.W.; Chacon-Golcher, E.; Kwan, J.W.; Leung, K.N.; Reijonen, J.

    2002-05-22

    The Source Injector Program for the US Heavy Ion Fusion Virtual National Laboratory is currently exploring the feasibility of using RF gas plasma sources for a HIF driver. This source technology is presently the leading candidate for the multiple aperture concept, in which bright millimeter size beamlets are extracted and accelerated electrostatically up to 1 MeV before the beamlets are allowed to merge and form 1 A beams. Initial experiments have successfully demonstrated simultaneously high current density, {approx} 100 mA/cm{sup 2} and fast turn on, {approx} 1 {micro}s. These experiments were also used to explore operating ranges for pressure and RF power. Results from these experiments are presented as well as progress and plans for the next set of experiments for these sources.

  10. Gasification of biomass in water\\/gas-stabilized plasma for syngas production

    Microsoft Academic Search

    M. Hrabovsky; M. Konrad; V. Kopecky; M. Hlina; T. Kavka; G. van Oost; E. Beeckman; B. Defoort

    2006-01-01

    The experimental reactor PLASGAS for plasma pyrolysis and vitrification equipped with the hybrid gas-water stabilized torch\\u000a was used in the experiments. The plasma torch is characterized by low density, high temperature plasma with very low mass\\u000a flow rates and high enthalpy. High plasma enthalpy is advantageous for adjustment of higher reaction temperatures with high\\u000a energy efficiency. Gasification of biomass was

  11. A study of gas flow pattern, undercutting and torch modification in variable polarity plasma arc welding

    NASA Technical Reports Server (NTRS)

    Mcclure, John C.; Hou, Haihui Ron

    1994-01-01

    A study on the plasma and shield gas flow patterns in variable polarity plasma arc (VPPA) welding was undertaken by shadowgraph techniques. Visualization of gas flow under different welding conditions was obtained. Undercutting is often present with aluminum welds. The effects of torch alignment, shield gas flow rate and gas contamination on undercutting were investigated and suggestions made to minimize the defect. A modified shield cup for the welding torch was fabricated which consumes much less shield gas while maintaining the weld quality. The current torch was modified with a trailer flow for Al-Li welding, in which hot cracking is a critical problem. The modification shows improved weldablility on these alloys.

  12. Disinfection of Staphylococcus Aureus by pulsed non-thermal atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Mirpour, Shahriar; Ghoranneviss, Mahmood; Shahgoli, Farhad

    2011-10-01

    The aim of this paper was to study the effect of low-temperature atmospheric plasma jet on non-pathogenic bacteria's colonies. In this regard, Germicidal effect of time and distance of ICP He and He/N2 plasma jet on Staphylococcus Aureus were reported. The gas discharges were generated by a 40 KHz high voltage power supply which led to the inductively coupled plasma. The results showed that He/N2 enhance the sterilization time in comparison of He plasma. To the best of our knowledge this is the first study which has compared the effect of sterilization of ICP Helium and Helium-Nitrogen plasma in listed conditions. Also, the distance dependence showed that the germicidal effect was not linear the distance of electrode and sample. The protein leakage test and SEM of bacteria morphology confirmed the sterilization effect of non-thermal atmospheric pressure plasma jet.

  13. Role of neutral gas in scrape-off layer tokamak plasma

    NASA Astrophysics Data System (ADS)

    Bisai, N.; Jha, R.; Kaw, P. K.

    2015-02-01

    Neutral gas in scrape-off layer of tokamak plasma plays an important role as it can modify the plasma turbulence. In order to investigate this, we have derived a simple two-dimensional (2D) model that consists of electron continuity, quasi-neutrality, and neutral gas continuity equations using neutral gas ionization and charge exchange processes. Simple 1D profile analysis predicts neutral penetration depth into the plasma. Growth rate obtained from the linear theory has been presented. The 2D model equations have been solved numerically. It is found that the neutral gas reduces plasma fluctuations and shifts spectrum of the turbulence towards lower frequency side. The neutral gas fluctuation levels have been presented. The numerical results have been compared with Aditya tokamak experiments.

  14. Effects of rf-bias power on plasma parameters in a low gas pressure inductively coupled plasma

    SciTech Connect

    Lee, Hyo-Chang; Lee, Min-Hyong; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2010-02-15

    Remarkable changes of the electron temperature and the plasma density by increasing bias power were observed in low gas pressure inductively coupled plasma (ICP) by the measurement of electron energy distribution function (EEDF). As the bias power increases, the electron temperature increased with accompanying the evolution of the EEDF from a bi-Maxwellian to a Maxwellian distribution. However, a different trend of the plasma density was observed with a dependence on the ICP powers. When the ICP power was relatively small or the discharge is in capacitive mode (E mode), the plasma density increased considerably with the bias power, while decrease of the plasma density was observed when the discharge is in inductive mode (H mode). The change of the plasma density can be explained by the balance between total power absorption and power dissipation.

  15. Influence of the gas-flow Reynolds number on a plasma column in a glass tube

    SciTech Connect

    Jin, Dong Jun; Uhm, Han S.; Cho, Guangsup [Department of Electronic and Biological Physics, Kwangwoon University, 20 Kwangwon-Ro, Nowon-Gu, Seoul 139-701 (Korea, Republic of)] [Department of Electronic and Biological Physics, Kwangwoon University, 20 Kwangwon-Ro, Nowon-Gu, Seoul 139-701 (Korea, Republic of)

    2013-08-15

    Atmospheric-plasma generation inside a glass tube is influenced by gas stream behavior as described by the Reynolds number (Rn). In experiments with He, Ne, and Ar, the plasma column length increases with an increase in the gas flow rate under laminar flow characterized by Rn < 2000. The length of the plasma column decreases as the flow rate increases in the transition region of 2000 < Rn < 4000. For a turbulent flow beyond Rn > 4000, the length of the plasma column is short in front of the electrode, eventually leading to a shutdown.

  16. Effect of a deuterium gas puff on the edge plasma in NSTX

    NASA Astrophysics Data System (ADS)

    Zweben, S. J.; Stotler, D. P.; Bell, R. E.; Davis, W. M.; Kaye, S. M.; LeBlanc, B. P.; Maqueda, R. J.; Meier, E. T.; Munsat, T.; Ren, Y.; Sabbagh, S. A.; Sechrest, Y.; Smith, D. R.; Soukhanovskii, V.

    2014-09-01

    This paper describes a detailed examination of the effects of a relatively small pulsed deuterium gas puff on the edge plasma and edge turbulence in NSTX. This gas puff caused little or no change in the line-averaged plasma density or total stored energy, or in the edge density and electron temperature up to the time of the peak of the gas puff. The radial profile of the D? light emission and the edge turbulence within this gas puff did not vary significantly over its rise and fall, implying that these gas puffs did not significantly perturb the local edge plasma or edge turbulence. These measurements are compared with modeling by DEGAS 2, UEDGE, and with simplified estimates for the expected effects of this gas puff.

  17. Effect of Deuterium Gas Puff On The Edge Plasma In NSTX

    SciTech Connect

    Zweben, S. J.

    2014-02-20

    This paper describes a detailed examination of the effects of a relatively small pulsed deuterium gas puff on the edge plasma and edge turbulence in NSTX. This gas puff caused little or no change in the line-averaged plasma density or total stored energy, or in the edge density and electron temperature up to the time of the peak of the gas puff. The radial profile of the D? light emission and the edge turbulence within this gas puff did not vary significantly over its rise and fall, implying that these gas puffs did not significantly perturb the local edge plasma or edge turbulence. These measurements are compared with modeling by DEGAS 2, UEDGE, and with simplified estimates for the expected effects of this gas puff.

  18. Influence of reactive oxygen species on the sterilization of microbes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of reactive oxygen species on living cells, including various microbes, is discussed. A sterilization experiment with bacterial endospores reveals that an argoneoxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby indicating that oxygen radic...

  19. Uranium plasma emission at gas-core reaction conditions

    NASA Technical Reports Server (NTRS)

    Williams, M. D.; Jalufka, N. W.; Hohl, F.; Lee, J. H.

    1976-01-01

    The results of uranium plasma emission produced by two methods are reported. For the first method a ruby laser was focused on the surface of a pure U-238 sample to create a plasma plume with a peak plasma density of about 10 to the 20th power/cu cm and a temperature of about 38,600 K. The absolute intensity of the emitted radiation, covering the range from 300 to 7000 A was measured. For the second method, the uranium plasma was produced in a 20 kilovolt, 25 kilojoule plasma-focus device. The 2.5 MeV neutrons from the D-D reaction in the plasma focus are moderated by polyethylene and induce fissions in the U-235. Spectra of both uranium plasmas were obtained over the range from 30 to 9000 A. Because of the low fission yield the energy input due to fissions is very small compared to the total energy in the plasma.

  20. The role of the gas/plasma plume and self-focusing in a gas-filled capillary discharge waveguide for high-power laser-plasma applications

    E-print Network

    Ciocarlan, C.; Islam, M. R.; Ersfeld, B.; Abuazoum, S.; Wilson, R.; Aniculaesei, C.; Welsh, G. H.; Vieux, G.; Jaroszynski, D. A.

    2013-01-01

    The role of the gas/plasma plume at the entrance of a gas-filled capillary discharge plasma waveguide in increasing the laser intensity has been investigated. Distinction is made between neutral gas and hot plasma plumes that, respectively, develop before and after discharge breakdown. Time-averaged measurements show that the on-axis plasma density of a fully expanded plasma plume over this region is similar to that inside the waveguide. Above the critical power, relativistic and ponderomotive selffocusing lead to an increase in the intensity, which can be nearly a factor of 2 compared with the case without a plume. When used as a laser plasma wakefield accelerator, the enhancement of intensity can lead to prompt electron injection very close to the entrance of the waveguide. Self-focusing occurs within two Rayleigh lengths of the waveguide entrance plane in the region, where the laser beam is converging. Analytical theory and numerical simulations show that, for a density of 3.01018 cm3, the peak normalized...

  1. The role of the gas/plasma plume and self-focusing in a gas-filled capillary discharge waveguide for high-power laser-plasma applications

    SciTech Connect

    Ciocarlan, C. [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom) [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Department of Nuclear Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, 76900 Bucharest-Magurele (Romania); Wiggins, S. M.; Islam, M. R.; Ersfeld, B.; Abuazoum, S.; Wilson, R.; Aniculaesei, C.; Welsh, G. H.; Vieux, G.; Jaroszynski, D. A. [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom)] [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2013-09-15

    The role of the gas/plasma plume at the entrance of a gas-filled capillary discharge plasma waveguide in increasing the laser intensity has been investigated. Distinction is made between neutral gas and hot plasma plumes that, respectively, develop before and after discharge breakdown. Time-averaged measurements show that the on-axis plasma density of a fully expanded plasma plume over this region is similar to that inside the waveguide. Above the critical power, relativistic and ponderomotive self-focusing lead to an increase in the intensity, which can be nearly a factor of 2 compared with the case without a plume. When used as a laser plasma wakefield accelerator, the enhancement of intensity can lead to prompt electron injection very close to the entrance of the waveguide. Self-focusing occurs within two Rayleigh lengths of the waveguide entrance plane in the region, where the laser beam is converging. Analytical theory and numerical simulations show that, for a density of 3.0 × 10{sup 18} cm{sup ?3}, the peak normalized laser vector potential, a{sub 0}, increases from 1.0 to 1.85 close to the entrance plane of the capillary compared with a{sub 0} = 1.41 when the plume is neglected.

  2. Experiments on the gas protection of porous refractory materials from oxidation and erosion in plasma flows

    Microsoft Academic Search

    G. M. Shchegolev; V. M. Sleptsov; Yu. P. Kukota; E. M. Prshedromirskaya

    1967-01-01

    The possibility is demonstrated of counteracting high-temperature oxidation and erosion of the surface of refractory metals in plasma flows using protective gas films created by a blast through porous walls.

  3. Gas-confined barrier discharges: a simplified model for plasma dynamics in flame environments

    E-print Network

    Guerra-Garcia, Carmen

    In this paper we evaluate the dynamics of non-thermal plasmas developing in extremely non-homogeneous environments. We present the gas-confined barrier discharge (GBD) concept and justify its importance as a first step to ...

  4. Water vapor plasma technology for biomass conversion to synthetic gas

    Microsoft Academic Search

    V. Grigaitien?; V. Snapkauskien?; P. Valatkevi?ius; A. Tamoši?nas; V. Valin?ius

    2011-01-01

    This study presents the results of experimental investigation on the development of water vapor plasma technology for conversion of biomass and destruction of hazardous substances. Similar plasma technology is also foreseen for the synthesis of micro- and nanostructured catalytic coatings for wide range of applications.An experimental DC plasma torch with button type hot cathode and step formed copper anode, operating

  5. Zero-Dimensional MHD Modelling of Two Gas-Puff Staged Pinch Plasma with FINITE-? Effect

    NASA Astrophysics Data System (ADS)

    Mirza, Arshad M.; Deeba, F.; Ahmed, K.; Haseeb, M. Q.

    2007-04-01

    The implosion dynamics of two gas-puff staged pinch plasma is investigated using zero-dimensional MHD code in the presence of pressure gradients. A modified snow-plow model has been used to describe the dynamics of staged pinch plasma. Our numerical results demonstrate that fusion parameters can be achieved for an optimum choice of density ratio of the test to driver gas and kinetic to magnetic pressure ratio.

  6. Hybrid (plasma + gas tungsten arc) weldability of modified 12% Cr ferritic stainless steel

    Microsoft Academic Search

    Emel Taban; Erdinc Kaluc; Alfred Dhooge

    2009-01-01

    This paper deals with the hybrid (plasma+gas tungsten arc) welding properties of 12mm thick modified 12% Cr ferritic stainless steel complying with EN 1.4003 and UNS S41003 steels with a carbon content of 0.01% to improve the weldability. The root passes of the butt welds were produced with plasma arc welding (PAW) without filler metal while gas tungsten arc welding

  7. Review of the critical velocity of gas--plasma interaction. I. Experimental observations

    Microsoft Academic Search

    Danielsson

    1973-01-01

    A review is given of the experimental investigations concerning the ; critical velocity of the interaction between a neutral gas and a plasma in ; relative motion. In most of the experiments this critical velocity is equivalent ; to a voltage limitation of a discharge through a partially ionized, magnetized ; plasma. The critical velocity phenomenon can have been of

  8. Conversion of natural gas to C 2 hydrocarbons via cold plasma technology

    Microsoft Academic Search

    Jing Lü; Zhenhua Li

    2010-01-01

    The plasma technology served as a tool in unconventional catalysis has been used in natural gas conversion, because the traditional catalytic methane oxidative coupling reaction must be performed at high temperature on account of the stability of methane molecule. The focus of this research is to develop a process of converting methane to C2 hydrocarbons with non-equilibrium plasma technology at

  9. Performance evaluation of nonthermal plasma reactors for NO oxidation in diesel engine exhaust gas treatment

    Microsoft Academic Search

    Toshiaki Yamamoto; B. S. Rajanikanth; Masaaki Okubo; Tomoyuki Kuroki; Masaya Nishino

    2003-01-01

    The discharge plasma-chemical hybrid process for NOx removal from the flue gas emissions is an extremely effective and economical approach in comparison with the conventional selective catalytic reduction system. In this paper we bring out a relative comparison of several discharge plasma reactors from the point of NO removal efficiency. The reactors were either energized by AC or by repetitive

  10. Formation of laser plasma channels in a stationary gas A. Dunaevsky

    E-print Network

    Formation of laser plasma channels in a stationary gas A. Dunaevsky Department of Astrophysical and Thermonuclear Research (TRINITI), Troitsk 142190, Russia J. Greenberg School of Engineering and Applied Science. However, the formation of the ablative plasma on the walls of pinholes by the wings of radial profile

  11. Simulation of gas dynamics and electromagnetic processes in high-current arc plasmas

    Microsoft Academic Search

    Lei Zhang Schlitz

    1998-01-01

    A strategy is developed to numerically study thermal plasma arc columns under high-current conditions. Necessary assumptions are made to focus the investigation on the interactions between gas flow, energy transport and the electromagnetic field. In order to study the macroscopic behavior of a thermal plasma under the conditions of local thermodynamic equilibrium, coupled Navier-Stokes and Maxwell's equations are derived. While

  12. Operation of ferroelectric plasma sources in a gas discharge modea... A. Dunaevskyb)

    E-print Network

    of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary as vacuum sources of the surface discharge plasma.1 Imagine a bulk of ferroelectric ceramics placedOperation of ferroelectric plasma sources in a gas discharge modea... A. Dunaevskyb) and N. J

  13. On monitoring of gas leak in the plasma vacuum process with optical emission spectroscopy

    Microsoft Academic Search

    S. C. Pyun; J. H. Kwon; S. J. You; D. J. Seong; J. H. Kim; Y. H. Shin; J. S. Shin

    2010-01-01

    A new method of monitoring for small leak in the plasma vacuum process using optical emission spectroscopy (OES) system is proposed and compared with other diagnostic tools (pressure gauge, and voltage probe). The result shows that the proposed method (algorithm) is more sensitive to detect gas leakage during plasma discharge operation than other diagnostic tools (pressure gauge, and voltage probe)

  14. Instabilities in fissioning plasmas as applied to the gas-core nuclear rocket-engine

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The compressional wave spectrum excited in a fissioning uranium plasma confined in a cavity such as a gas cored nuclear reactor, is studied. Computer results are presented that solve the fluid equations for this problem including the effects of spatial gradients, nonlinearities, and neutron density gradients in the reactor. Typically the asymptotic fluctuation level for the plasma pressure is of order 1 percent.

  15. Application of the Gas-Filled Capillary Discharge Waveguide to Laser-Plasma Acceleration

    SciTech Connect

    Spence, D.J.; Gonsalves, A.J.; McKenna, C.M.; Hooker, S.M. [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom)

    2004-12-07

    The application of the gas-filled capillary discharge waveguide to laser-plasma accelerators is reviewed. The results of experiments to guide high-intensity laser pulses in capillaries with circular or square cross-sections are described. The relation between capillary diameter, guided spot size, and plasma density are explored, and a possible new hybrid regime of guiding is identified.

  16. Electron interaction cross sections for a low-temperature 'plasma-like' gas mixture

    NASA Astrophysics Data System (ADS)

    Hargreaves, L. R.; Brunton, J. R.; Brunger, M. J.; Buckman, S. J.

    2010-12-01

    Electron interaction cross sections for species found in low-temperature industrial plasma environments are a crucial component to allow for accurate modeling of those plasmas. However, such data are still rarely reported in the literature, due to the complexities of working with such highly reactive species in a laboratory. Here, absolute differential cross section measurements for a 'plasma-like' gas mixture, containing CF3I, CF3, I2, I and C2F6, are reported.

  17. Resemblance in gas composition of Ar-N2-O2 plasmas and Ar-NO plasmas

    NASA Astrophysics Data System (ADS)

    van Helden, J. H.; Zijlmans, R. A. B.; Schram, D. C.; Engeln, R.

    2009-05-01

    We measured the steady-state gas composition of plasmas produced from Ar-N2-O2 mixtures and Ar-NO mixtures with quantitative mass spectrometry. In the former, mainly N2 and O2, but also a significant amount of nitric oxide (NO) was formed, i.e. up to 5% of the background gas was NO. In the inverse experiment, in which NO was admixed to an argon plasma, up to 92% of the NO was converted into N2 and O2. The observed molecules are mostly generated in wall association processes but also by gas phase reactions between N atoms and O2 molecules leading to NO. The two types of plasmas show a strong mutual resemblance in the steady-state gas composition if substantial dissociation can be reached in the residence time of the gases in the plasma, i.e. ?5% NO and ?95% N2 and O2, although the starting conditions are completely different. It seems that in first order the system prefers to produce the most thermodynamically stable molecules.

  18. Gas?Kinetic Temperature of Planar High?Frequency Capacitive Discharge Plasma in N2\\/CO2\\/He Gas Mixtures

    Microsoft Academic Search

    V. V. Azharonok; I. I. Filatova; V. D. Shimanovich; L. N. Orlov

    2001-01-01

    Using methods of emission spectroscopy, we have determined the gas-kinetic temperature fields of planar high-frequency capacitive discharge plasma in N2\\/CO2\\/He gas mixtures depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture. It is shown that the dominant contribution to the neutral component heating in the center of the discharge chamber is made by the processes

  19. Fullerene-rare gas mixed plasmas in an electron cyclotron resonance ion source.

    PubMed

    Asaji, T; Ohba, T; Uchida, T; Minezaki, H; Ishihara, S; Racz, R; Muramatsu, M; Biri, S; Kitagawa, A; Kato, Y; Yoshida, Y

    2014-02-01

    A synthesis technology of endohedral fullerenes such as Fe@C60 has developed with an electron cyclotron resonance (ECR) ion source. The production of N@C60 was reported. However, the yield was quite low, since most fullerene molecules were broken in the ECR plasma. We have adopted gas-mixing techniques in order to cool the plasma and then reduce fullerene dissociation. Mass spectra of ion beams extracted from fullerene-He, Ar or Xe mixed plasmas were observed with a Faraday cup. From the results, the He gas mixing technique is effective against fullerene destruction. PMID:24593515

  20. Fullerene-rare gas mixed plasmas in an electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Asaji, T.; Ohba, T.; Uchida, T.; Minezaki, H.; Ishihara, S.; Racz, R.; Muramatsu, M.; Biri, S.; Kitagawa, A.; Kato, Y.; Yoshida, Y.

    2014-02-01

    A synthesis technology of endohedral fullerenes such as Fe@C60 has developed with an electron cyclotron resonance (ECR) ion source. The production of N@C60 was reported. However, the yield was quite low, since most fullerene molecules were broken in the ECR plasma. We have adopted gas-mixing techniques in order to cool the plasma and then reduce fullerene dissociation. Mass spectra of ion beams extracted from fullerene-He, Ar or Xe mixed plasmas were observed with a Faraday cup. From the results, the He gas mixing technique is effective against fullerene destruction.

  1. Fullerene-rare gas mixed plasmas in an electron cyclotron resonance ion source

    SciTech Connect

    Asaji, T., E-mail: asaji@oshima-k.ac.jp; Ohba, T. [Oshima National College of Maritime Technology, 1091-1 Komatsu, Suo-oshima, Oshima, Yamaguchi 742-2193 (Japan)] [Oshima National College of Maritime Technology, 1091-1 Komatsu, Suo-oshima, Oshima, Yamaguchi 742-2193 (Japan); Uchida, T.; Yoshida, Y. [Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)] [Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan); Minezaki, H.; Ishihara, S. [Graduate School of Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)] [Graduate School of Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan); Racz, R.; Biri, S. [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem Tér 18/c (Hungary)] [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem Tér 18/c (Hungary); Muramatsu, M.; Kitagawa, A. [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)] [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kato, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)] [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2014-02-15

    A synthesis technology of endohedral fullerenes such as Fe@C{sub 60} has developed with an electron cyclotron resonance (ECR) ion source. The production of N@C{sub 60} was reported. However, the yield was quite low, since most fullerene molecules were broken in the ECR plasma. We have adopted gas-mixing techniques in order to cool the plasma and then reduce fullerene dissociation. Mass spectra of ion beams extracted from fullerene-He, Ar or Xe mixed plasmas were observed with a Faraday cup. From the results, the He gas mixing technique is effective against fullerene destruction.

  2. Modeling of non-thermal plasma in flammable gas mixtures

    Microsoft Academic Search

    A. P. Napartovich; I. V. Kochetov; S. B. Leonov

    2008-01-01

    An idea of using plasma-assisted methods of fuel ignition is based on non-equilibrium generation of chemically active species that speed up the combustion process. It is believed that gain in energy consumed for combustion acceleration by plasmas is due to the non-equilibrium nature of discharge plasma, which allows radicals to be produced in an above-equilibrium amount. Evidently, the size of

  3. Ozone-mist spray sterilization for pest control in agricultural management

    NASA Astrophysics Data System (ADS)

    Ebihara, Kenji; Mitsugi, Fumiaki; Ikegami, Tomoaki; Nakamura, Norihito; Hashimoto, Yukio; Yamashita, Yoshitaka; Baba, Seiji; Stryczewska, Henryka D.; Pawlat, Joanna; Teii, Shinriki; Sung, Ta-Lun

    2013-02-01

    We developed a portable ozone-mist sterilization system to exterminate pests (harmful insects) in agricultural field and greenhouse. The system is composed of an ozone generator, an ozone-mist spray and a small container of ozone gas. The ozone generator can supply highly concentrated ozone using the surface dielectric barrier discharge. Ozone-mist is produced using a developed nozzle system. We studied the effects of ozone-mist spray sterilization on insects and agricultural plants. The sterilization conditions are estimated by monitoring the behavior of aphids and observing the damage of the plants. It was shown that aphids were exterminated in 30 s without noticeable damages of the plant leaves. The reactive radicals with strong oxidation potential such as hydroxyl radical (*OH), hydroperoxide radical (*HO2), the superoxide ion radical (*O2?) and ozonide radical ion (*O3?) can increase the sterilization rate for aphids. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  4. Degradation of phenol in water using a gas–liquid phase pulsed discharge plasma reactor

    Microsoft Academic Search

    Jie Li; Masayuki Sato; Takayuki Ohshima

    2007-01-01

    In this paper, a gas–liquid phase pulsed discharge plasma reactor was used to dispose phenol in aqueous solutions. The effect of pulsed peak voltage and energy, solution conductivity, solution pH, and additive gas varieties on degradation efficiency of phenol was reviewed in the research. The observed results showed that degradation efficiency of phenol increased with the increase of pulsed peak

  5. Modification of the carbon fiber\\/matrix interface using gas plasma treatment with acetylene and oxygen

    Microsoft Academic Search

    S. Feih; P. Schwartz

    1998-01-01

    Acetylene and oxygen gas plasma treatment of PAN-based carbon fibers to increase the interfacial shear strength was investigated. The effects of different gas mixtures and exposure times were studied. Changes in the fiber surface chemistry were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, and wetting tests. The adhesion of epoxy to treated fibers was measured using the

  6. CONTOURS OF LINES OF IONS IN A PLASMA OF A POSITIVE COLUMN OF A GAS DISCHARGE

    Microsoft Academic Search

    Zakharova

    1956-01-01

    The contours of lines of Ar ions in the plasma of the positive column of ; a gas discharge are investigated. The discharge tube is 140 mm long and 4 mm in ; diam. The gas pressure at the discharge varied from 0.5 to 2.0 mm of Hg, and the ; intensity of the discharge current was between 0.2 and

  7. Mechanisms of disruptions caused by noble gas injection into tokamak plasmas

    Microsoft Academic Search

    D. Kh. Morozov; E. I. Yurchenko; V. E. Lukash; E. O. Baronova; Yu. I. Pozdnyakov; V. A. Rozhansky; I. Yu. Senichenkov; I. Yu. Veselova; R. Schneider

    2005-01-01

    Noble gas injection for disruption mitigation in DIII-D is simulated. The simulation of the first two stages of the disruption is performed: the first one is the neutral gas jet penetration through the background plasmas, and the second one is the instability growth. In order to simulate the first stage, the MHD pellet code LLP with improved radiation model for

  8. Sterilization: past, present, future.

    PubMed

    Ross, J A

    1992-01-01

    Globally, sterilization protects more couples from pregnancy than any other contraceptive method. However, use of sterilization has grown only gradually and annual rates of adoption remain low. The high prevalence of sterilization can be explained by its excellent continuation rate, its appeal to a broad age range at the time of adoption, and its long history of availability. International patterns show that sterilization users are concentrated in the two large countries of China and India, but numerous smaller countries also have high proportions of couples using the method. Four personal characteristics differentiate its use within each country: age, parity, residence, and sex. A new projection method indicates that approximately 159 million sterilization adoptions are expected between 1990 and 2000, half of them in China. Most future sterilization users will be found where they have been in the past, due to their concentration in China and India and to the large carry-over of current users in all countries. Projections for sterilization are more dependable than are those for other contraceptive methods, because most current users are young enough to remain in the pool of active users for 10 years. They constitute a large component of the expected total in the year 2000--about 269 million users, or 29 percent of all couples. PMID:1523698

  9. [Sterilization and eugenics].

    PubMed

    Shasha, Shaul M

    2011-04-01

    The term "eugenics" was coined by Francis Galton in 1883 and was defined as the science of the improvement of the human race by better breeding. "Positive eugenics" referred to methods of encouraging the "most fit" to reproduce more often, while "negative eugenics" was related to ways of discouraging or preventing the "less fit" from reproducing by birth control and sterilization. Many western countries adopted eugenics programs including Britain, Canada, Norway, Australia, Switzerland and others. In Sweden more then 62,000 "unfits" were forcibly sterilized. Many states in the U.S.A. had adopted marriage laws with eugenics criteria including forced sterilization. Approximately 64,000 individuals were sterilized. Eugenics considerations also lay behind the adoption of the Immigration Restriction Act of 1924. The Largest plan on eugenics was adopted by the Nazi regime in Germany. Hundreds of thousands of people, who were viewed as being "unfit", were forcibly sterilized by different methods: Surgical sterilization or castration with severe complications and high mortality rates. X-ray irradiation. The method was suggested by Brack, and tested by Schuman using prisoners in Block No. 10 in Auschwitz and Birkenau. Experiments were also performed by Brack on prisoners using the "window method". "Klauberg method"--injection of irritating materials into the uterus. Experiments were conducted using the plant Caladium Seguinum which was believed to have sterilization and castration properties. PMID:22164927

  10. Propagation mechanisms of guided streamers in plasma jets: the influence of electronegativity of the surrounding gas

    NASA Astrophysics Data System (ADS)

    Schmidt-Bleker, Ansgar; Norberg, Seth A.; Winter, Jörn; Johnsen, Eric; Reuter, S.; Weltmann, K. D.; Kushner, Mark J.

    2015-06-01

    Atmospheric pressure plasma jets for biomedical applications are often sustained in He with small amounts of, for example, O2 impurities and typically propagate into ambient air. The resulting poorly controlled generation of reactive species has motivated the use of gas shields to control the interaction of the plasma plume with the ambient gas. The use of different gases in the shield yields different behavior in the plasma plume. In this paper, we discuss results from experimental and computational investigations of He plasma jets having attaching and non-attaching gas shields. We found that negative ion formation in the He-air mixing region significantly affects the ionization wave dynamics and promotes the propagation of negative guided streamers through an electrostatic focusing mechanism. Results from standard and phase resolved optical emission spectroscopy ratios of emission from states of N2 and He imply different electric fields in the plasma plume depending on the composition of the shielding gas. These effects are attributed to the conductivity in the transition region between the plasma plume and the shield gas, and the immobile charge represented by negative ions. The lower conductivity in the attaching mixtures enables more extended penetration of the electric field whereas the negative ions aid in focusing the electrons towards the axis.

  11. Compact laser plasma EUV source based on a gas puff target for metrology

    NASA Astrophysics Data System (ADS)

    Fiedorowicz, Henryk; Bartnik, Andrzej; Jarocki, Roman; Kostecki, Jerzy; Mikolajczyk, Janusz; Rakowski, Rafal; Szczurek, Miroslaw

    2003-06-01

    In the paper a newly developed compact laser plasma EUV source is presented. The source is based on the double-stream gas puff target approach. The targets are formed by pulsed injection of high-Z gas (xenon) into a hollow stream of low-Z gas (helium) using the valve system composed of two electromagnetic valves and equipped with the double-nozzle setup. The outer stream of gas confines the inner stream improving the gas puff target characteristics (higher density of high-Z gas at longer distance from the nozzle output). It causes efficient absorption of laser energy in a plasma and strong EUV production. The source has been developed in the frame of the EUV sources development project under the MEDEA+ program.

  12. Interpretation of the gas flow field modification induced by guided streamer (‘plasma bullet’) propagation

    NASA Astrophysics Data System (ADS)

    Papadopoulos, P. K.; Vafeas, P.; Svarnas, P.; Gazeli, K.; Hatzikonstantinou, P. M.; Gkelios, A.; Clément, F.

    2014-10-01

    Atmospheric-pressure non-equilibrium plasmas of noble gases in the form of ‘bullets’ have attracted considerable attention, against cold low-pressure or thermal atmospheric-pressure plasmas, for multidisciplinary scientific fields such as material science and biomedicine, due to their unique compatible features. A key factor for the efficiency of most of these systems is the interaction between the noble-gas channel, where the ‘bullets’ (streamers) propagate, and the plasma itself. It is the object of this paper to demonstrate this interaction and to provide the explanation on the gas flow field modification induced by the plasma ignition. A three-dimensional numerical model incorporating most of the governing equations, schlieren imaging and UV–visible high-resolution optical emission spectroscopy are applied. In accordance with the present results, the mechanism leading to the flow field alteration is clearly related to the electrohydrodynamic force, while it is demonstrated that the gas temperature plays a minor role.

  13. Effects of admixture gas on the production of (18)F radioisotope in plasma focus devices.

    PubMed

    Talaei, Ahmad; Sadat Kiai, S M; Zaeem, A A

    2010-12-01

    In this article, the effect of admixture gas on the heating and cooling of pinched plasma directly related to the enhancement or reduction of (18)F production through the (16)O((3)He, p)(18)F is considered in the plasma focus devices. It is shown that by controlling the velocity of added Oxygen particles mixed with the working helium gas into the plasma focus chamber, one can increase the current and decrease the confinement time (plasma heating) or vice verse (plasma cooling). The highest level of nuclear activities of (18)F was found around 16% of the Oxygen admixture participation and was about 0.35 MBq in the conditions of 20 kJ, 0.1 Hz and after 2 min operating of Dena PF. However, in the same condition, but for the frequency of 1 Hz, the level of activity increased up to 3.4 MBq. PMID:20579896

  14. Negative Ion Crystal Formation in Nonequilibrium Dusty Plasma at a Gas Evacuation from Technological Devices for Vacuum Support

    Microsoft Academic Search

    Nikolai A. Azarenkov; Alexei M. Egorov; Vasyl I. Maslov; Ivan N. Onishchenko; Darya Yu. Frolova

    2002-01-01

    Plasma crystal formation (or so called ion crystal formation) are investigated now intensively (see, for example, [1-5]). In particular, the formation of the plasma crystals has been observed in experiments at providing of nonequilibrium state. If in equilibrium dusty plasma there was no plasma crystal but at providing of nonequilibrium state at a gas evacuation from devices for vacuum support

  15. Contrib. Plasma Phys. 51, No. 2-3, 293 296 (2011) / DOI 10.1002/ctpp.201000061 LTE Experimental Validation in a Gas Metal Arc Welding Plasma

    E-print Network

    2011-01-01

    Validation in a Gas Metal Arc Welding Plasma Column F. Valensi1,2 , S. Pellerin1 , A. Boutaghane3 , K, France 7 CTAS-Air Liquide Welding, Saint Ouen l'Aum^one, 95315 Cergy-Pontoise cedex, France Received 12 Spectroscopy, Boltzmann Plot, Sola method, LTE. During gas metal arc welding (GMAW), the plasma obtained has

  16. ESCAMPIG XXII, Greifswald, Germany, July 15-19, 2014 4. Plasma surface interaction Gas aggregation source based on pulsed plasma sputtering for the synthesis

    E-print Network

    Paris-Sud XI, Université de

    ESCAMPIG XXII, Greifswald, Germany, July 15-19, 2014 4. Plasma surface interaction Gas aggregation source based on pulsed plasma sputtering for the synthesis of PtX catalytic nanoclusters A. Caillard(*)1 rue de la férollerie 45071 Orléans, France (*) amael.caillard@univ-orleans.fr The gas

  17. INTEGRATED TRANSPORT CODE SYSTEM FOR MULTICOMPONENT HIGH-b b PLASMAS IN THE GAS-DYNAMIC TRAP

    Microsoft Academic Search

    A. N. Karpushov; A. V. Anikeev; K. Noack; S. L. Strogalova

    The multicomponent GDT plasmas consist of the target plasma ñ isotropic Maxwellian electrons and ions, fast (sloshing) ions and neutral components. The warm ìbackgroundî plasma (target) with electron temperature 3-120 eV and density of (1-20) ·1013 cm-3 produced by a plasma gun and (or) by gas-puffing. The different methods of cold-gas fuelling was proposed and experimentally tested on the GDT.

  18. Plasma ionization frequency, edge-to-axis density ratio, and density on axis of a cylindrical gas discharge

    SciTech Connect

    Palacio Mizrahi, J. H. [Physics Department, Technion, Haifa 32000 (Israel)

    2014-06-15

    A rigorous derivation of expressions, starting from the governing equations, for the ionization frequency, edge-to-axis ratio of plasma density, plasma density at the axis, and radially averaged plasma density in a cylindrical gas discharge has been obtained. The derived expressions are simple and involve the relevant parameters of the discharge: Cylinder radius, axial current, and neutral gas pressure. The found expressions account for ion inertia, ion temperature, and changes in plasma ion collisionality.

  19. Observation on retrieved Hylamer glenoids in shoulder arthroplasty: problems associated with sterilization by gamma irradiation in air.

    PubMed

    Rockwood, Charles A; Wirth, Michael A

    2002-01-01

    Hylamer is an ultra-high molecular weight polyethylene that was used in the glenoid prosthesis of the Global Shoulder. It was developed from a joint venture with DePuy Orthopaedics, Inc, and E.I. DuPont Company. In presterilization evaluations it was noted to have improved mechanical strength with superior creep and wear resistance. However, after sterilization was performed with gamma irradiation in an air environment from 1990 to 1993, the Hylamer glenoids were affected by oxidation, which altered the mechanical properties, and they became brittle and eroded. From 1993 to 1995 Hylamer glenoids were sterilized by gamma irradiation in a nitrogen environment. From 1995 to 1998 sterilization was by gas plasma processes, which do not create the oxidation problem. Since 1998 the glenoid prosthesis of the Global Shoulder has been made exclusively of Enduron and is gas sterilized. The primary purpose of this article is to provide orthopaedic surgeons the best information available about Hylamer glenoids. We make suggestions concerning the diagnosis and treatment of the patients who had a Hylamer glenoid inserted between 1990 and 1993. PMID:11988733

  20. Simulation of the gas-phase processes in remote-plasma-activated chemical-vapor deposition of silicon dielectrics using rare gas-silane-

    E-print Network

    Kushner, Mark

    Simulation of the gas-phase processes in remote-plasma-activated chemical-vapor deposition- duce a flux of specificradicals to the substrate. Remote-plasma-activated chemical-vapor deposition September1991;acceptedfor publication 17January 1992) Remote-plasma-activatedchemical-vapor deposition

  1. Note: Design and investigation of a multichannel plasma-jet triggered gas switch

    NASA Astrophysics Data System (ADS)

    Tie, Weihao; Liu, Xuandong; Zhang, Qiaogen; Liu, Shanhong

    2014-07-01

    We described the fabrication and testing of a multichannel plasma-jet triggered gas switch (MPJTGS). A novel six-channel annular micro-plasma-gun was embedded in the trigger electrode to generate multichannel plasma jets as a nanosecond trigger pulse arrived. The gas breakdown in multiple sites of the spark gap was induced and fixed around jet orifices by the plasma jets. We tested the multichannel discharge characteristics of the MPJTGS in two working modes with charge voltage of 50 kV, trigger voltage of +40 kV (25 ns rise time), and trigger energy of 240 J, 32 J, and 2 J, respectively, at different working coefficients. Results show that the average number of discharge channels increased as the trigger energy increased, and decreased as the working coefficient decreased. At a working coefficient of 87.1% and trigger energy of 240 J, the average number of discharge channels in Mode II could reach 4.1.

  2. Quantification of clotiazepam in human plasma by gas chromatography–mass spectrometry

    Microsoft Academic Search

    Sung-Hoon Ahn; Han-Joo Maeng; Tae-Sung Koo; Dae-Duk Kim; Chang-Koo Shim; Suk-Jae Chung

    2006-01-01

    An analytical procedure was developed and validated for the quantification of clotiazepam in human plasma. After subjecting plasma samples to solid-phase extraction, the extract was evaporated and the residue re-constituted. An aliquot of the mixture was injected onto a gas chromatography–mass spectrometry system. The detector response was linear for clotiazepam concentrations in the range of 5–200ng\\/ml. Intra- and inter-day precision

  3. Quantification of naltrexone and 6,?-naltrexol in plasma and milk using gas chromatography–mass spectrometry

    Microsoft Academic Search

    Chooi Fen Chan; Gregory M. Chiswell; Roberta Bencini; L. Peter Hackett; Leon J. Dusci; Kenneth F. Ilett

    2001-01-01

    A selective gas chromatography–mass spectrometry method using solid-phase extraction has been developed for the detection and quantification of naltrexone and its metabolite, 6,?-naltrexol in plasma and milk from humans and sheep at pharmacologically relevant concentrations. Di- or tri-acetyl derivatives were formed and quantified by selected-ion monitoring. Recoveries of naltrexone (30 ?g\\/l) and 6,?-naltrexol (250 ?g\\/l) from both human plasma and

  4. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H. (Oak Ridge, TN); Hanson, Gregory R. (Clinton, TN); Storey, John M. (Oak Ridge, TN); Raridon, Richard J. (Oak Ridge, TN); Armfield, Jeffrey S. (Upsilanti, MI); Bigelow, Timothy S. (Knoxville, TN); Graves, Ronald L. (Knoxville, TN)

    2001-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime (about 40 ps), high frequency (about 5G hz), high power bursts of low-duty factor microwaves sufficient to generate a dielectric barrier discharge and passing a gas to treated through the discharge so as to cause dissociative reduction of the exhaust gases. The invention also includes a reactor for generating the non-thermal plasma.

  5. Surface decontamination of simulated chemical warfare agents using a nonequilibrium plasma with off-gas monitoring

    Microsoft Academic Search

    Trevor M. Moeller; M. Lizabeth Alexander; Mark H. Engelhard; Daniel J. Gaspar; Maria L. Luna; Patricia M. Irving

    2002-01-01

    InnovaTek, Inc., Richland, WA, is developing a surface decontamination technology that utilizes active species generated in a nonequilibrium corona plasma. The plasma technology was tested against dimethyl-methyl phosphonate (DMMP), a simulant for the chemical agent Sarin. Gas chromatograph mass spectrometry analysis showed that a greater than four log10 destruction of the DMMP on an aluminum surface was achieved in a

  6. Investigation of a Light Gas Helicon Plasma Source for the VASIMR Space Propulsion System

    Microsoft Academic Search

    Jared P. Squire; Franklin R. Chang-Diaz; Verlin T. Jacobson; Tim W. Glover; F. Wally Baity; Mark D. Carter; Richard H. Goulding; Roger D. Bengtson; Edgar A. Bering

    2003-01-01

    An efficient plasma source producing a high-density (~1019 m-3) light gas (e.g. H, D, or He) flowing plasma with a high degree of ionization is a critical component of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept. The high degree of ionization and a low neutral background pressure are important to eliminate the problem of radial loss and axial drag

  7. Investigation of a Light Gas Helicon Plasma Source for the VASIMR Space Propulsion System

    Microsoft Academic Search

    Jared P. Squire; Franklin R. Chang-Diaz; Verlin T. Jacobson; Tim W. Glover; F. Wally Baity; Mark D. Carter; Richard H. Goulding; Roger D. Bengtson; Edgar A. Bering

    2003-01-01

    An efficient plasma source producing a high-density (?1019 m?3) light gas (e.g. H, D, or He) flowing plasma with a high degree of ionization is a critical component of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept. The high degree of ionization and a low neutral background pressure are important to eliminate the problem of radial loss and axial drag

  8. Determination of schizandrin in human plasma by gas chromatography-mass spectrometry

    Microsoft Academic Search

    Hiromasa Ono; Yutaka Matsuzaki; Yoko Wakui; Shuichi Takeda; Yukinobu Ikeya; Sakae Amagaya; Masao Maruno

    1995-01-01

    Schizandrin (SZ) is one of the lignan components from Schisandra fruits. A highly sensitive and precise method for the determination of SZ in human plasma was developed involving selected-ion monitoring with gas chromatography-mass spectrometry using a fused-silica capillary column. A 0.1-ml plasma sample was used for solid-phase extraction. A good linear relationship was obtained in the concentration range studied (2.0–500

  9. Stabilization of liquified-inert-gas jets for laser-plasma generation

    Microsoft Academic Search

    B. A. M. Hansson; M. Berglund; O. Hemberg; H. M. Hertz

    2004-01-01

    We investigate the hydrodynamic properties of liquified-inert-gas jets in a vacuum with a special emphasis on their stability. Such jets have applications as targets for laser-plasma generation of soft-x-ray and extreme-ultraviolet (EUV) radiation. An important example is the liquid-xenon-jet laser-plasma source, one of the source candidates for EUV lithography. A simple hydrodynamic model in not sufficient to explain experimental observations

  10. Stabilization of liquified-inert-gas jets for laser–plasma generation

    Microsoft Academic Search

    B. A. M. Hansson; M. Berglund; O. Hemberg; H. M. Hertz

    2004-01-01

    We investigate the hydrodynamic properties of liquified-inert-gas jets in a vacuum with a special emphasis on their stability. Such jets have applications as targets for laser–plasma generation of soft-x-ray and extreme-ultraviolet (EUV) radiation. An important example is the liquid-xenon-jet laser-plasma source, one of the source candidates for EUV lithography. A simple hydrodynamic model in not sufficient to explain experimental observations

  11. Mechanisms of gas precipitation in plasma-exposed tungsten

    SciTech Connect

    R. D. Kolasinski; D. F. Cowgill; D. C. Donovan; M. Shimada

    2012-05-01

    Precipitation in subsurface bubbles is a key process that governs how hydrogen isotopes migrate through and become trapped within plasma-exposed tungsten. We describe a continuum-scale model of hydrogen diffusion in plasma-exposed materials that includes the effects of precipitation. The model can account for bubble expansion via dislocation loop punching, using an accurate equation of state to determine the internal pressure. This information is used to predict amount of hydrogen trapped by bubbles, as well as the conditions where the bubbles become saturated. In an effort to validate the underlying assumptions, we compare our results with published positron annihilation and thermal desorption spectroscopy data, as well as our own measurements using the tritium plasma experiment (TPE).

  12. Plasma assisted synthesis of WS2 for gas sensing applications

    NASA Astrophysics Data System (ADS)

    O'Brien, Maria; Lee, Kangho; Morrish, Rachel; Berner, Nina C.; McEvoy, Niall; Wolden, Colin A.; Duesberg, Georg S.

    2014-11-01

    We report the plasma assisted synthesis of WS2 thin films and demonstrate their suitability for sensing applications. This was achieved by using a H2S plasma to sulphurise WO3 films at temperatures as low as 500 °C. This is a significant step towards semiconductor compatible growth of transition metal dichalcogenide (TMD) thin films without the need for highly elevated temperatures. We found that the electrical transport in thin films is highly sensitive to the presence of NH3. A sensitivity of 1.4 ppm NH3 in nitrogen at room temperature has been achieved, demonstrating the potential of 2D TMD films for sensing applications.

  13. Plasma and neutral dynamics in a simulated tokamak gas target divertor

    NASA Astrophysics Data System (ADS)

    Schmitz, L.; Merriman, B.; Blush, L.; Lehmer, R.; Conn, R. W.; Doerner, R.; Grossman, A.; Najmabadi, F.

    1995-08-01

    A stationary, detached ionization front is observed in an experimentally simulated divertor plasma (n?3×1019 m-3, kTe?20 eV) interacting with a hydrogen gas target. With a neutral hydrogen density, n0?2×1021 m-3, the electron temperature at the simulated divertor target is reduced to kTe target?2.5 eV. Up to 97% of the electron heat flux (?7 MW/m2) is dissipated by dissociation and ionization losses and hydrogen line radiation. The plasma pressure is observed to peak near the ionization front, and a plasma flow reversal is observed in the region of reversed pressure gradient. Classical momentum flow parallel to the magnetic field and anomalous cross-field particle transport are found. The plasma flow is strongly damped by ion-neutral collisions and is subsonic. Numerical results from a one-and-one-half dimensional (11/2-D) coupled plasma-neutral fluid model (incorporating radial particle transport, recycling, and neutral gas injection) agree well with the experimental data, and indicate that the electron heat flow is classical and well described by a harmonic flux limit. The scale length of the parallel plasma pressure gradient in a gas target is found to depend on the neutral density, the electron temperature, and the cross-field diffusion coefficient.

  14. Terahertz wave generation from gas plasma using a phase compensator with attosecond phase-control accuracy

    SciTech Connect

    Dai Jianming; Zhang, X.-C. [Center for Terahertz Research, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2009-01-12

    We report the use of a precise phase compensator for the generation of intense terahertz waves from laser-induced gas plasma excited by a femtosecond pulse ({omega}) and its second harmonic (2{omega}) at both close contact and standoff distances. The attosecond accuracy phase-control capability of the device enables further optimization of the terahertz emission from gas plasma and elimination of the temporal walkoff between the {omega} and 2{omega} pulses traveling in dispersive media, resulting in intense terahertz generation at a distance of over 100 m by sending the optical beams far away and focusing them locally.

  15. Antimicrobial outcomes in plasma medicine

    NASA Astrophysics Data System (ADS)

    Ryan, Thomas P.; Stalder, Kenneth R.; Woloszko, Jean

    2015-03-01

    Plasma is referred to as the fourth state of matter and is frequently generated in the environment of a strong electric field. The result consists of highly reactive species--ions, electrons, reactive atoms and molecules, and UV radiation. Plasma Medicine unites a number of fields, including Physics, Plasma Chemistry, Cell Biology, Biochemistry, and Medicine. The treatment modality utilizes Cold Atmospheric Plasma (CAP), which is able to sterilize and treat microbes in a nonthermal manner. These gas-based plasma systems operate at close to room temperature and atmospheric pressure, making them very practical for a range of potential treatments and are highly portable for clinical use throughout the health care system. The hypothesis is that gas based plasma kills bacteria, fungus, and viruses but spares mammalian cells. This paper will review systematic work which shows examples of systems and performance in regards to antimicrobial effects and the sparing of mammalian cells. The mechanism of action will be discussed, as well as dosing for the treatment of microbial targets, including sterilization processes, another important healthcare need. In addition, commercial systems will be overviewed and compared, along with evidence-based, patient results. The range of treatments cover wound treatment and biofilms, as well as antimicrobial treatment, with little chance for resistance and tolerance, as in drug regimens. Current clinical studies include applications in dentistry, food treatment, cancer treatment, wound treatment for bacteria and biofilms, and systems to combat health care related infections.

  16. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H. (Oak Ridge, TN); Hanson, Gregory R. (Clinton, TN); Storey, John M. (Oak Ridge, TN); Raridon, Richard J. (Oak Ridge, TN); Armfield, Jeffrey S. (Ypsilanti, MI); Bigelow, Timothy S. (Knoxville, TN); Graves, Ronald L. (Knoxville, TN)

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  17. Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

    NASA Astrophysics Data System (ADS)

    DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.

    2008-02-01

    Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.

  18. Residual stress in plasma-sprayed ceramic turbine tip and gas-path seal specimens

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Mcdonald, G.; Mullen, R. L.

    1983-01-01

    The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials. Previously announced in STAR as N83-28380

  19. A carbon monoxide gas sensor using oxygen plasma modified carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Weiyun; Fam, Derrick Wen Hui; Yin, Zongyou; Sun, Ting; Tan, Hui Teng; Liu, Weiling; Iing Yoong Tok, Alfred; Boey, Yin Chiang Freddy; Zhang, Hua; Hng, Huey Hoon; Yan, Qingyu

    2012-10-01

    Carbon monoxide (CO) is a highly toxic gas that can be commonly found in many places. However, it is not easily detected by human olfaction due to its colorless and odorless nature. Therefore, highly sensitive sensors need to be developed for this purpose. Carbon nanotubes (CNTs) have an immense potential in gas sensing. However, CNT-based gas sensors for sensing CO are seldom reported due to the lack of reactivity between CO and CNTs. In this work, O2 plasma modified CNT was used to fabricate a CNT gas sensor. The plasma treated CNTs showed selectively towards CO, with the capability of sensing low concentrations of CO (5 ppm) at room temperature, while the pristine CNTs showed no response. UV spectra and oxygen reduction reaction provided evidence that the difference in sensing property was due to the elimination of metallic CNTs and enhancement of the oxygen reduction property.

  20. Feather-like He plasma plumes in surrounding N2 gas

    NASA Astrophysics Data System (ADS)

    Xian, Y. B.; Zou, D. D.; Lu, X. P.; Pan, Y.; Ostrikov, K.

    2013-08-01

    Effects of surrounding gases on the propagation of room-temperature atmospheric-pressure plasma jets are reported. A highly unusual feather-like plasma plume is observed only when N2 is used as surrounding gas. The He concentration on the axis at the starting point of the feather-like plume is ˜0.85 of the maximum value and is independent on the He flow rates. High-speed optical imaging reveals that dim diffuse plasmas emerge just behind the bright head of the plasma bullet at the starting point of the feather-like plume. These results help tailoring surface exposure in emerging applications of plasma jets in medicine and nanotechnology.

  1. Sterile neutrinos in the early universe

    SciTech Connect

    Malaney, R.A. (Lawrence Livermore National Lab., CA (USA)); Fuller, G.M. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics)

    1990-11-14

    We discuss the role played by right-handed sterile neutrinos in the early universe. We show how well known {sup 4}He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented. 12 refs.

  2. Biological Sterilization of Returned Mars Samples

    NASA Technical Reports Server (NTRS)

    Allen, C. C.; Albert, F. G.; Combie, J.; Bodnar, R. J.; Hamilton, V. E.; Jolliff, B. L.; Kuebler, K.; Wang, A.; Lindstrom, D. J.; Morris, P. A.

    1999-01-01

    Martian rock and soil, collected by robotic spacecraft, will be returned to terrestrial laboratories early in the next century. Current plans call for the samples to be immediately placed into biological containment and tested for signs of present or past life and biological hazards. It is recommended that "Controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized." While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth. The sterilization method should be capable of destroying a wide range of organisms with minimal effects on the geologic samples. A variety of biological sterilization techniques and materials are currently in use, including dry heat, high pressure steam, gases, plasmas and ionizing radiation. Gamma radiation is routinely used to inactivate viruses and destroy bacteria in medical research. Many commercial sterilizers use Co-60 , which emits gamma photons of 1.17 and 1.33 MeV. Absorbed doses of approximately 1 Mrad (10(exp 8) ergs/g) destroy most bacteria. This study investigates the effects of lethal doses of Co-60 gamma radiation on materials similar to those anticipated to be returned from Mars. The goals are to determine the gamma dose required to kill microorganisms in rock and soil samples and to determine the effects of gamma sterilization on the samples' isotopic, chemical and physical properties. Additional information is contained in the original extended abstract.

  3. Density measurements of a high-density pulsed gas jet for laser-plasma interaction studies

    Microsoft Academic Search

    Y. M. Li; R. Fedosejevs

    1994-01-01

    The density profile of a pulsed high-density gas jet developed for laser-plasma interaction experiments has been measured. The measurements were carried out using interferometry and Abet inversion of the resultant fringe shifts to obtain gas densities. The jet produces high densities of up to 6*1020 cm-3 for nitrogen and helium gases at 200 mu m outside the nozzle tip. The

  4. Measurement and analysis of gas-puff density distributions for plasma radiation source z pinches

    Microsoft Academic Search

    D. Mosher; B. V. Weber; B. Moosman; R. J. Commisso; P. Coleman; E. Waisman; H. Sze; Y. Song; D. Parks; P. Steen; J. Levine; B. Failor; A. Fisher

    2001-01-01

    High-sensitivity interferometry measurements of initial density distributions are reviewed for a wide range of gas-puff nozzles used in plasma radiation source (PRS) z-pinch experiments. Accurate gas distributions are required for determining experimental load parameters, modeling implosion dynamics, understanding the radiation properties of the stagnated pinch, and for predicting PRS performance in future experiments. For a number of these nozzles, a

  5. Study of lasing and discharge plasma parameters in noble gas\\/metal atom mixtures

    Microsoft Academic Search

    Tadeusz M. Adamowicz

    2003-01-01

    Results of research on metal ion lasers are presented. They were obtained using novel diagnostic methods for measurements lasing parameters of noble gas-metal vapor systems and determination of metal atom diffusion coefficients in noble gases. Influence of helium 3He isotope on plasma and laser parameters in He-noble gas and metal atom mixtures was studied as well as some elementary processes

  6. NO 2 gas sensitivity of carbon nanotubes obtained by plasma enhanced chemical vapor deposition

    Microsoft Academic Search

    C. Cantalini; L. Valentini; L. Lozzi; I. Armentano; J. M. Kenny; S. Santucci

    2003-01-01

    Carbon nanotubes (CNTs) thin films deposited by plasma enhanced chemical vapor deposition on Si\\/Si3N4 substrates provided with platinum interdigital electrodes have been investigated as resistive gas sensors towards NO2 oxidizing gas.The electrical response has been measured exposing the films to sub-ppm NO2 concentrations (10–100ppb in dry air) at different operating temperatures ranging between 25 and 215°C. The response to NO2

  7. Electron beam optimization using 3D printed gas cells in a laser-plasma accelerator

    NASA Astrophysics Data System (ADS)

    Behm, Keegan; Vargas, Michael; Schumaker, William; Zhao, Zhen; Chvykov, Vladimir; Maksimchuk, Anatoly; Yanovsky, Victor; Thomas, Alexander; Krushelnick, Karl

    2013-10-01

    Laser driven tabletop accelerators have made it possible to produce tunable relativistic beams of electrons. One of the ways in which these electron beams can be optimized is by changing the plasma environment that creates and accelerates the electrons. Using a rapid prototyped gas cell built with a 3D printer to create a relatively contained environment for the plasma has increased the electron beam pointing stability and has created more monoenergetic beams than what was achieved with a gas jet. Several different gas cell designs have been studied and tested to determine the optimum configuration and gas mixture for stable, monoenergetic electron beams. Two-staged gas cells have produced the highest quality electron beams with greatest pointing and beam stability. The purpose of the two-staged gas cell is to divide the laser wakefield acceleration process into two steps, an injection stage, where a helium-nitrogen mixture is used to inject more charge into the wake of the laser, and an acceleration stage where pure helium is used to create a plasma conducive for accelerating the electrons captured in the first stage.

  8. Growth of carbon nanotubes by microwave plasma chemical vapor deposition using CH 4 and CO 2 gas mixture

    Microsoft Academic Search

    M. Chen; Chieng-Ming Chen; Chia-Fu Chen

    2002-01-01

    Carbon nanotubes (CNTs) were grown vertically and aligned on Fe catalytic nanoparticles which were deposited on a Si substrate at low temperature using CH4 and CO2 gas mixtures. A dynamic form of optical emission spectroscopy was used to detect the species in the plasma. These data show the dominant species in gas phase reaction. The composition of plasma significantly affects

  9. Gas cleaning with semi-wet type plasma reactor

    Microsoft Academic Search

    Alokkumar Chakrabarti; Akira Mizuno; Kazuo Shimizu; Tsutomu Matsuoka; Satoshi Furuta

    1995-01-01

    An experimental study on the removal of NH3, NO, NOx in concentration of 10-40 ppm in air has been carried out using plasma chemical reactions in a streamer corona discharge. The results of the performance of dry type and semi-wet type reactors are compared. The effects of different type of applied voltages such as rectangular pulse, 60-Hz sinusoidal, and 18-kHz

  10. Neutral gas plasma interactions and critical ionization velocity phenomena. Interim report

    Microsoft Academic Search

    Papadopoulos

    1983-01-01

    The interplay of collisional and collisionless phenomena in the interaction of a magnetoplasma streaming through neutral gas produces some of the most fascinating plasma physics phenomena. A key notion controlling such interactions is the existence of a critical velocity (U sub c) effect postulated in an ad hoc fashion by Alfven, in his model of the formation of the solar

  11. Gas dynamic effects on formation of carbon dimers in laser-produced plasmas

    E-print Network

    Harilal, S. S.

    Gas dynamic effects on formation of carbon dimers in laser-produced plasmas K. F. Al-Shboul, S. S. Harilal,a) and A. Hassanein School of Nuclear Engineering and Center for Materials Under Extreme and nitrogen pressures on the dynamics of molecular species formation during laser ablation of carbon

  12. Key factors in achieving ultra-broadband THz emission from a laser-induced gas plasma

    Microsoft Academic Search

    Volker Blank; Mark D. Thomson; Hartmut G. Roskos

    2011-01-01

    We demonstrate how the observed emission of ultra-broadband THz pulses (>100 THz) from a two-color (?-2?) laser-induced gas plasma is strongly dictated by the precise spectral and temporal characteristics of the input optical fields. OCIS codes: (190.4380) Nonlinear optics, four-wave mixing; (300.6495) Spectroscopy, terahertz

  13. Thermal Phenomena in Gas Confinement Dielectric Tube of the VASIMR Helicon Plasma

    Microsoft Academic Search

    Dan Berisford; R. Bengtson; L. Raja; J. Squire; L. Cassidy; J. Chauncery; G. McCaskill

    2007-01-01

    A quartz dielectric tube provides gas confinement in the helicon discharge of the VASIMR (Variable Specific Impulse Magnetoplasma Rocket) experiment. Despite highly aligned magnetic field lines to confine the plasma in the discharge, significant thermal heating of the dielectric tube occurs. We perform infrared camera imaging studies of heating of the tube with varying operational parameters of the experiment. Results

  14. Effect of gas inlet positions on plasma carburizing of AISI 1020 steel

    Microsoft Academic Search

    Shi Li; Rafael R. Manory

    1995-01-01

    Samples of 1020 grade steel were carburized for 30 min at 1000 °C in a d.c. plasma system enclosed in a tube furnace. A gas mixture consisting of methane (CH4) and hydrogen was bled into the system using one of two inlet positions located at the top and the bottom of the reactor. The latter position was close to the

  15. The effect of clusters and heterogeneous reactions on non-equilibrium plasma flue gas cleaning

    Microsoft Academic Search

    B. V. Potapkin; M. A. Deminsky; A. A. Fridman; V. D. Rusanov

    1995-01-01

    Theoretical investigation of the effect of molecular clusters and aerosol particles on non-equilibrium plasma flue gas cleaning was made in this paper. Two types of heterogeneous reactions in aerosol and clusters are considered. It was shown that in both cases these reactions are essential in the evaluation of chemical composition. As a result of theoretical approach and modelling, the optimum

  16. Effect of neutral gas heating in argon radio frequency inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Chin, O. H.; Jayapalan, K. K.; Wong, C. S.

    2014-08-01

    Heating of neutral gas in inductively coupled plasma (ICP) is known to result in neutral gas depletion. In this work, this effect is considered in the simulation of the magnetic field distribution of a 13.56 MHz planar coil ICP. Measured electron temperatures and densities at argon pressures of 0.03, 0.07 and 0.2 mbar were used in the simulation whilst neutral gas temperatures were heuristically fitted. The simulated results showed reasonable agreement with the measured magnetic field profile.

  17. Investigation of a Gas Jet-Produced Hollow Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N; Blumenfeld, I.; Hogan, M.J.; Siemann, R.H.; Walz, D.R.; /SLAC; Davidson, A.W.; Huang, C.; /UCLA

    2009-05-21

    The effect of ion motion and the need for practical positron propagation in a plasma wakefield accelerator (PWFA) have incited interest in hollow plasma channels. These channels are typically assumed to be cylindrically symmetric; however, a different geometry might be easier to achieve. The introduction of an obstruction into the outlet of a high Mach number gas jet can produce two parallel slabs of gas separated by a density depression. Here, there is a detailed simulation study of the density depression created in such a system. This investigation reveals that the density depression is insufficient at the desired plasma density. However, insights from the simulations suggest another avenue for the creation of the hollow slab geometry.

  18. Hybrid Particle-Continuum Methods for Nonequilibrium Gas and Plasma Flows

    SciTech Connect

    Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI (United States)

    2011-05-20

    Two different hybrid particle-continuum methods are described for simulation of nonequilibrium gas and plasma dynamics. The first technique, used for nonequilibrium hypersonic gas flows, uses either a continuum description or a particle method throughout a flow domain based on local conditions. This technique is successful in reproducing the results of full particle simulations at a small fraction of the cost. The second method uses a continuum model of the electrons combined with a particle description of the ions and atoms for simulating plasma jets. The physical accuracy of the method is assessed through comparisons with plasma plume measurements obtained in space. These examples illustrate that the complex physical phenomena associated with nonequilibrium conditions can be simulated with physical accuracy and numerical efficiency using such hybrid approaches.

  19. Radiation sterilization of ketoprofen

    NASA Astrophysics Data System (ADS)

    Katušin-Ražem, Branka; Hamitouche, Katia; Maltar-Strme?ki, Nadica; Kos, Karmen; Puci?, Irina; Britvi?-Budicin, Smiljana; Ražem, Dušan

    2005-06-01

    Radiation sterilization of ketoprofen (KP) dry powder was investigated by selected physico-chemical methods. High-performance liquid chromatography, ultraviolet spectrophotometry, infrared spectrophotometry, differential scanning calorimetry, X-ray diffraction and electron spin resonance spectroscopy did not show any significant degradation at sterilization dose 25 kGy. To determine the nature, extent and direction of radiation-induced changes, KP was irradiated to extremely high doses, much higher than necessary to achieve sterility. The irradiated KP did not show any difference of XRD patterns up to 200 kGy; with DSC and IR some changes were detected only above 1000 and 2000 kGy, respectively; HPLC has shown about 5% destruction at 2000 kGy. Acetyl benzophenon (AcBph) was generated by irradiation with G(AcBph)=(1.6±0.1)×10 -8 mol J -1. Ames test has shown no mutagenicity of KP irradiated with 3000 kGy or of the oily mixure of radiolytic products isolated from it. Solid KP has proven to be very stable on irradiation, and irradiation has been found to be a suitable method for its sterilization.

  20. Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching.

    PubMed

    Olde Riekerink, M B; Engbers, G H M; Wessling, M; Feijen, J

    2002-01-15

    Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF(4)) or carbon dioxide (CO(2)), 47-49 W, 0.04-0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top layer of the membranes was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements to obtain information about surface structure, chemistry, and wettability, respectively. The membrane properties (e.g., permeability, selectivity, fouling) were studied by waterflux measurements, molecular weight cutoff measurements, and fouling experiments with bovine serum albumin. CO(2) plasma treatment resulted in gradual etching of the membrane's dense top layer. Permeation and selectivity changed significantly for treatment times of 0-15 min for CTA and 5-60 min for CAB membranes. Moreover, CTA membranes were hydrophilized during CO(2) plasma treatment whereas CF(4) plasma treatment led to hydrophobic surfaces due to strong fluorination of the top layer. This study shows that gas plasma etching can tailor the properties of asymmetric cellulose acetate membranes by simultaneously modifying the chemistry and structure of the top layer. The low fouling properties of CTA membranes were thereby largely maintained. PMID:16290368

  1. Pulsed plasma treatment of polluted gas using wet-/low-temperature corona reactors

    SciTech Connect

    Shimizu, Kazuo; Kinoshita, Katsuhiro; Yanagihara, Kenya; Rajanikanth, B.S.; Katsura, Shinji; Mizuno, Akira [Toyohashi Univ. of Technology, Aichi (Japan). Dept. of Ecological Engineering] [Toyohashi Univ. of Technology, Aichi (Japan). Dept. of Ecological Engineering

    1997-09-01

    Application of pulsed plasma for gas cleaning is gaining prominence in recent years, mainly from the energy consideration point of view. Normally, the gas treatment is carried out at or above room temperature by the conventional dry-type corona reactor. However, this treatment is still inadequate for the removal of certain stable gases present in the exhaust/flue gas mixture. The authors report here some interesting results of treatment of such stable gases like N{sub 2}O with pulsed plasma at subambient temperature. Also reported in this paper are improvements in DeNO/DeNO{sub x} efficiency using unconventional wet-type reactors, designed and fabricated by us, and operating at different subambient temperatures. DeNO/DeNO{sub x} by the pulsed-plasma process is mainly due to oxidation, but reduction takes place at the same time. When the wet-type reactor was used, the NO{sub 2} product was absorbed by water film and higher DeNO{sub x} efficiency could be achieved. Apart from laboratory tests on simulated gas mixtures, field tests were also carried out on the exhaust gas of an 8-kW diesel engine. A comparative analysis of the various tests are presented, together with a note on the energy consideration.

  2. Nonlinear Structure of the Diffusing Gas-Metal Interface in a Thermonuclear Plasma

    NASA Astrophysics Data System (ADS)

    Molvig, Kim; Vold, Erik L.; Dodd, Evan S.; Wilks, Scott C.

    2014-10-01

    This Letter describes the theoretical structure of the plasma diffusion layer that develops from an initially sharp gas-metal interface. The layer dynamics under isothermal and isobaric conditions is considered so that only mass diffusion (mixing) processes can occur. The layer develops a distinctive structure with asymmetric and highly nonlinear features. On the gas side of the layer the diffusion coefficient goes nearly to zero, causing a sharp "front," or well defined boundary between mix layer and clean gas with similarities to the Marshak thermal waves. Similarity solutions for the nonlinear profiles are found and verified with full ion kinetic code simulations. A criterion for plasma diffusion to significantly affect burn is given.

  3. Simultaneous determination of nitrate and nitrite in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Kage, Shigetoshi; Kudo, Keiko; Ikeda, Noriaki

    2002-09-01

    We devised a sensitive and simple method for the simultaneous determination of nitrate and nitrite in human plasma, using extractive alkylation. These inorganic anions were alkylated with pentafluorobenzyl bromide, using tetradecyldimethylbenzylammonium chloride as the phase-transfer catalyst, with 1,3,5-tribromobenzene as an internal standard. The derivatives were analyzed by gas chromatography-mass spectrometry, using the negative-ion chemical ionization mode with isobutane as the reagent gas. Calibration curves for nitrate and nitrite were linear over the concentration range of 0.01 to 1.0 micromol/mL in plasma, and the lower limit of detection for both compounds was 0.005 micromol/mL. The accuracy and precision of this method were evaluated and coefficients of variation were lower than 10.4%. Blood nitrate and nitrite concentrations of six victims who committed suicide by inhaling automobile exhaust gas could be determined using our method. PMID:12220012

  4. Measurements of gas preionization for plasma radiation sources

    Microsoft Academic Search

    B. Moosman; B. V. Weber; S. J. Stephanakis; R. J. Commisso; A. Fisher

    1999-01-01

    Azimuthally symmetric ultraviolet (UV) preionization of the outer periphery of a gas puff z pinch, prior to current initiation, may reduce the growth of magnetically driven Rayleigh-Taylor instabilities or other nonuniformities affecting the final implosion stage of the pinch, leading to an improvement in K-shell x-ray yield. We report on measurements of a flashover UV photoionization scheme, capable of ionizing

  5. Removal of Elemental Mercury from a Gas Stream Facilitated by a Non-Thermal Plasma Device

    SciTech Connect

    Charles Mones

    2006-12-01

    Mercury generated from anthropogenic sources presents a difficult environmental problem. In comparison to other toxic metals, mercury has a low vaporization temperature. Mercury and mercury compounds are highly toxic, and organic forms such as methyl mercury can be bio-accumulated. Exposure pathways include inhalation and transport to surface waters. Mercury poisoning can result in both acute and chronic effects. Most commonly, chronic exposure to mercury vapor affects the central nervous system and brain, resulting in neurological damage. The CRE technology employs a series of non-thermal, plasma-jet devices to provide a method for elemental mercury removal from a gas phase by targeting relevant chemical reactions. The technology couples the known chemistry of converting elemental mercury to ionic compounds by mercury-chlorine-oxygen reactions with the generation of highly reactive species in a non-thermal, atmospheric, plasma device. The generation of highly reactive metastable species in a non-thermal plasma device is well known. The introduction of plasma using a jet-injection device provides a means to contact highly reactive species with elemental mercury in a manner to overcome the kinetic and mass-transfer limitations encountered by previous researchers. To demonstrate this technology, WRI has constructed a plasma test facility that includes plasma reactors capable of using up to four plasma jets, flow control instrumentation, an integrated control panel to operate the facility, a mercury generation system that employs a temperature controlled oven and permeation tube, combustible and mercury gas analyzers, and a ductless fume hood designed to capture fugitive mercury emissions. Continental Research and Engineering (CR&E) and Western Research Institute (WRI) successfully demonstrated that non-thermal plasma containing oxygen and chlorine-oxygen reagents could completely convert elemental mercury to an ionic form. These results demonstrate potential the application of this technology for removing elemental mercury from flue gas streams generated by utility boilers. On an absolute basis, the quantity of reagent required to accomplish the oxidation was small. For example, complete oxidation of mercury was accomplished using a 1% volume fraction of oxygen in a nitrogen stream. Overall, the tests with mercury validated the most useful aspect of the CR&E technology: Providing a method for elemental mercury removal from a gas phase by employing a specific plasma reagent to either increase reaction kinetics or promote reactions that would not have occurred under normal circumstances.

  6. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    PubMed

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness. PMID:20192469

  7. 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

  8. Plasma-produced phase-pure cuprous oxide nanowires for methane gas sensing

    SciTech Connect

    Cheng, Qijin, E-mail: ijin.cheng@xmu.edu.cn; Zhang, Fengyan [School of Energy Research, Xiamen University, Xiamen City, Fujian Province 361005 (China); Yan, Wei [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia); Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Randeniya, Lakshman [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia)

    2014-03-28

    Phase-selective synthesis of copper oxide nanowires is warranted by several applications, yet it remains challenging because of the narrow windows of the suitable temperature and precursor gas composition in thermal processes. Here, we report on the room-temperature synthesis of small-diameter, large-area, uniform, and phase-pure Cu{sub 2}O nanowires by exposing copper films to a custom-designed low-pressure, thermally non-equilibrium, high-density (typically, the electron number density is in the range of 10{sup 11}–10{sup 13}?cm{sup ?3}) inductively coupled plasmas. The mechanism of the plasma-enabled phase selectivity is proposed. The gas sensors based on the synthesized Cu{sub 2}O nanowires feature fast response and recovery for the low-temperature (?140?°C) detection of methane gas in comparison with polycrystalline Cu{sub 2}O thin film-based gas sensors. Specifically, at a methane concentration of 4%, the response and the recovery times of the Cu{sub 2}O nanowire-based gas sensors are 125 and 147?s, respectively. The Cu{sub 2}O nanowire-based gas sensors have a potential for applications in the environmental monitoring, chemical industry, mining industry, and several other emerging areas.

  9. Mechanisms of disruptions caused by noble gas injection into tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Morozov, D. Kh.; Yurchenko, E. I.; Lukash, V. E.; Baronova, E. O.; Pozdnyakov, Yu. I.; Rozhansky, V. A.; Senichenkov, I. Yu.; Veselova, I. Yu.; Schneider, R.

    2005-08-01

    Noble gas injection for disruption mitigation in DIII-D is simulated. The simulation of the first two stages of the disruption is performed: the first one is the neutral gas jet penetration through the background plasmas, and the second one is the instability growth. In order to simulate the first stage, the MHD pellet code LLP with improved radiation model for noble gas is used. Plasma cooling at this stage is provided by the energy exchange with the jet. The opacity effects in radiation losses are found to be important in the energy balance calculations. The magnetic surfaces in contact with the jet are cooled significantly; however, the temperature as well as the electric conductivity, remains high. The cooling front propagates towards the plasma centre. It has been shown that the cooling front is accompanied by strongly localized 'shark fin-like' perturbation in toroidal current density profile. The simplified cylindrical model shows that the cooling front is able to produce the internal kink-like mode with growth rate significantly higher than the tearing mode. The unstable kink perturbation obtained is non-resonant for any magnetic surface, both inside the plasma column, and in the vacuum space outside the separatrix. The mode disturbs mainly the core region. The growth time of the 'shark fin-like' mode is higher than the Alfven time by a factor of 10-100 for DIII-D parameters.

  10. Optimizing the sterilization of PLGA scaffolds for use in tissue engineering

    Microsoft Academic Search

    Chantal E Holy; Chantelle Cheng; John E Davies; Molly S Shoichet

    2000-01-01

    There are few suitable techniques available to sterilize biodegradable polyester three-dimensional tissue engineering scaffolds because they are susceptible to degradation and\\/or morphological degeneration by high temperature and pressure. We used a novel poly(lactide-co-glycolide) scaffold (Osteofoam™) to determine the optimal sterilization procedure — i.e. a sterile product with minimal degradation and deformation. Initial studies, found that an argon plasma created at

  11. Effects of shielding gas compositions on arc plasma and metal transfer in gas metal arc welding

    SciTech Connect

    Rao, Z. H. [School of Energy Science and Engineering, Central South University, Changsha 410083 (China); Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States); Liao, S. M. [School of Energy Science and Engineering, Central South University, Changsha 410083 (China); Tsai, H. L. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States)

    2010-02-15

    This article presents the effects of shielding gas compositions on the transient transport phenomena, including the distributions of temperature, flow velocity, current density, and electromagnetic force in the arc and the metal, and arc pressure in gas metal arc welding of mild steel at a constant current input. The shielding gas considered includes pure argon, 75% Ar, 50% Ar, and 25% Ar with the balance of helium. It is found that the shielding gas composition has significant influences on the arc characteristics; droplet formation, detachment, transfer, and impingement onto the workpiece; and weld pool dynamics and weld bead profile. As helium increases in the shielding gas, the droplet size increases but the droplet detachment frequency decreases. For helium-rich gases, the current converges at the workpiece with a 'ring' shape which produces non-Gaussian-like distributions of arc pressure and temperature along the workpiece surface. Detailed explanations to the physics of the very complex but interesting transport phenomena are given.

  12. Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures

    SciTech Connect

    Cremaschini, Claudio; Stuchlík, Zden?k [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)] [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)

    2014-04-15

    The problem of the transition from gas to plasma in gravitating axisymmetric structures is addressed under the assumption of having initial and final states realized by kinetic Maxwellian-like equilibria. In astrophysics, the theory applies to accretion-disc scenarios around compact objects. A formulation based on non-relativistic kinetic theory for collisionless systems is adopted. Equilibrium solutions for the kinetic distribution functions describing the initial neutral matter and the resulting plasma state are constructed in terms of single-particle invariants and expressed by generalized Maxwellian distributions. The final plasma configuration is related to the initial gas distribution by the introduction of appropriate functional constraints. Qualitative aspects of the solution are investigated and physical properties of the system are pointed out. In particular, the admitted functional dependences of the fluid fields carried by the corresponding equilibrium distributions are determined. Then, the plasma is proved to violate the condition of quasi-neutrality, implying a net charge separation between ions and electrons. This result is shown to be independent of the precise realization of the plasma distribution function, while a physical mechanism able to support a non-neutral equilibrium state is proposed.

  13. Gas laser for efficient sustaining a continuous optical discharge plasma in scientific and technological applications

    SciTech Connect

    Zimakov, V P; Kuznetsov, V A; Kedrov, A Yu; Solov'ev, N G; Shemyakin, A N; Yakimov, M Yu [A.Yu. Ishlinskii Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow (Russian Federation)

    2009-09-30

    A stable high-power laser is developed for the study and technical applications of a continuous optical discharge (COD). The laser based on the technology of a combined discharge in a scheme with a fast axial gas flow emits 2.2 kW at 10.6 {mu}m per meter of the active medium in continuous and repetitively pulsed regimes with the electrooptical efficiency 20%. The sustaining of the COD plasma in argon and air is demonstrated at the atmospheric pressure. The emission properties of the COD plasma are studied and its possible applications are discussed. (lasers)

  14. Investigation of methods for sterilization of potting compounds and mated surfaces

    NASA Technical Reports Server (NTRS)

    Tulius, J. J.; Daley, D. J.; Phillips, G. B.

    1972-01-01

    The feasibility of using formaldehyde-liberating synthetic resins or polymers for the sterilization of potting compounds, mated and occluded areas, and spacecraft surfaces was demonstrated. The detailed study of interrelated parameters of formaldehyde gas sterilization revealed that efficient cycle conditions can be developed for the sterilization of spacecraft components. It was determined that certain parameters were more important than others in the development of cycles for specific applications. The use of formaldehyde gas for the sterilization of spacecraft components provides NASA with a highly efficient method which is inexpensive, reproducible, easily quantitated, materials compatible, operationally simple, generally non-hazardous and not thermally destructive.

  15. Cytoplasmic male-sterility

    Microsoft Academic Search

    John R. Edwardson

    1956-01-01

    Cytoplasmic inheritance is of theoretical importance--it may be of even greater practical importance, for, when it involves malesterilitylas in many instances it does--it may make hybridization easier. It may also make possible the use of heterosis in plants otherwise difficult to hybridize. The effect of the cytoplasm on the inheritance of male-sterility was speculated on before the rediscovery of Mendel's

  16. plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, H. Y.; Jin, C. G.; Yang, Y.; Ye, C.; Zhuge, L. J.; Wu, X. M.

    2014-12-01

    As-deposited HfO2 films were modified by CHF3, C4F8, and mixed C4F8/O2 plasmas in a dual-frequency capacitively coupled plasma chamber driven by radio frequency generators of 60 MHz as the high frequency (HF) source and 2 MHz as the low frequency source (60/2 MHz). The influences of various surface plasma treatments under CHF3, C4F8, and C4F8/O2 were investigated in order to understand the chemical and structural changes in thin-film systems, as well as their influence on the electrical properties. Fluorine atoms were incorporated into the HfO2 films by either CHF3 or C4F8 plasma treatment; meanwhile, the C/F films were formed on the surface of the HfO2 films. The formation of C/F layers decreased the k value of the gate stacks because of its low dielectric constant. However, the addition of O2 gas in the discharge gases suppressed the formation of C/F layers. After thermal annealing, tetragonal HfO2 phase was investigated in both samples treated with CHF3 and C4F8 plasmas. However, the samples treated with O-rich plasmas showed monoclinic phase, which indicated that the addition of O plasmas could influence the Hf/O ratio of the HfO2 films. The mechanism of the t-HfO2 formation was attributed to oxygen insufficiency generated by the incorporation of F atoms. The capacitors treated with C4F8/O2 plasmas displayed the highest k value, which ascribed that the C/F layers were suppressed and the tetragonal phase of HfO2 was formed. Good electrical properties, especially on the hysteresis voltage and frequency dispersion, were obtained because the bulk traps were passivated by the incorporation of F atoms. However, the H-related traps were generated during the CHF3 plasma treatments, which caused the performance degradation. All the treated samples showed lower leakage current density than the as-deposited HfO2 films at negative bias due to the reduced trap-assisted tunneling by the incorporation of F to block the electrons transferring from metal electrode to the trap level.

  17. LIBS: Application to toxic metal concentration measurements in a plasma torch off-gas emission system

    SciTech Connect

    Singh, J.P.; Yueh, F.Y.; Zhang, H.; Etheridge, J.; Kirkland, R.L. [Mississippi State Univ., Mississippi State, MS (United States). Diagnostic Instrumentation and Analysis Lab.

    1995-12-31

    Laser-Induced Breakdown Spectroscopy (LIBS) has been used to monitor the metal concentrations of the off-gas system of a 250 kW plasma treatment system during vitrification of a Savannah River surrogate waste. LIBS spectra of different elements in the off-gas emission have been recorded in various spectral regions to select the appropriate spectral lines for the concentration measurements. The LIBS concentration measurement were then performed at different test run conditions. The results of various measurements are presented. These measurements demonstrated LIBS`s capability for real-time toxic metal monitoring.

  18. Investigation of the xenon excimer continuum in gas-discharge plasma

    SciTech Connect

    Baranov, I.Y.; Devdariani, A.Z.; Kryukov, N.A. [Univ. of Pervogo Maya, Peterhof (Russian Federation)] [and others

    1995-02-01

    The shape of the spectral band profile of xenon excimer molecule radiation in the near VUV region is studied as a function of the rare gas pressure. Excited states were formed in a pulsed gas discharge plasma is pure xenon. Spectral transitions BO{sub u}{sup +}{r_arrow}XO{sub g}{sup +} and A1{sub u}{r_arrow}XO{sub g}{sup +} were recorded. The spectrum transformation in discharge afterglow is studied. A model describing peculiarities of xenon excimer continuum formation is proposed. 13 refs., 5 figs.

  19. A plasma process controlled emissions off-gas demonstration

    SciTech Connect

    Battleson, D.; Kujawa, S.T. [MSE, Inc., Butte, MT (United States); Leatherman, G. [SAIC, Inc., Idaho Falls, ID (United States). STAR Center

    1995-12-31

    Thermal technologies are currently identified as playing an important role in the treatment of many DOE waste streams, and emissions from these processes will be scrutinized by the public, regulators, and stakeholders. For some time, there has been a hesitancy by the public to accept thermal treatment of radioactive contaminated waste because of the emissions from these processes. While the technology for treatment of emissions from these processes is well established, it is not possible to provide the public complete assurance that the system will be in compliance with air quality regulations 100% of the operating time in relation to allowing noncompliant emissions to exit the system. Because of the possibility of noncompliant emissions and the public`s concern over thermal treatment systems, it has been decided that the concept of a completely controlled emissions off-gas system should be developed and implemented on Department of Energy (DOE) thermal treatment systems. While the law of conservation of mass precludes a completely closed cycle system, it is possible to apply the complete control concept to emissions.

  20. RF gas plasma source development for heavy ion fusion

    SciTech Connect

    Ahle, L.E.; Hall, R.P.; Molvik, A.W.

    2002-02-22

    Presently the Heavy Ion Fusion Virtual National Laboratory is researching ion sources and injector concepts to understand how to optimize beam brightness over a range of currents (50-2000 mA argon equivalent). One concept initially accelerates millimeter size, milliamp beamlets to 1 MeV before merging them into centimeter size, ampere beams. Computer simulations have shown the final brightness of the merged beams is dominated by the emittance growth of the merging process, as long as the beamlets ion temperature is below a few eV. Thus, a RF multicusp source capable of high current density can produce beams with better brightness compared to ones extracted from a colder source with a large aperture and lower current density. As such, experiments have begun to develop a RF multicusp source capable of delivering one amp of extracted beam current. It is expected that it will require 10 kW of 13 MHz RF power delivered via a quartz shielded, one and half turn, four inch diameter antenna. Important considerations in the development of the source include the dependence of current density and beam ion temperature on consumed RF power and gas pressure. A fast rise time ({approx}100 ns) for the extracted beam pulse must also be achieved. Progress on these experiments will be presented.

  1. Diamond deposition from CF4-H2 mixed gas by microwave plasma

    NASA Astrophysics Data System (ADS)

    Kadono, M.; Inoue, T.; Miyanaga, A.; Yamazaki, S.

    1992-08-01

    We have deposited diamond films from CF4-H2 mixed gas by microwave plasma chemical vapor deposition method. The diamond films were characterized by scanning electron microscopy, x-ray diffraction, Raman spectrometry, and secondary ion mass spectrometry. (111) peak line of diamond crystal observed by x-ray diffraction and the peaks at 1333 cm-1 in the Raman spectroscopies of the deposited films showed that the films consisted of diamond. We observed that the quality of diamond films got better as the concentration (from 2.5% to 40%) of CF4 (tetrafluoromethane) got lower. It was observed from the optical emission spectra that CF, CF2, CF3, CH, and C2 fragments existed in the microwave plasma of CF4-H2 mixed gas. But it was observed from secondary ion mass spectroscopies that impurities (Si, F, and H) were present in the diamond films.

  2. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode

    NASA Astrophysics Data System (ADS)

    Poehlmann, Flavio R.; Cappelli, Mark A.; Rieker, Gregory B.

    2010-12-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 ?F, 50 to 200 nH, and 1 to 3 kV, respectively.

  3. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode.

    PubMed

    Poehlmann, Flavio R; Cappelli, Mark A; Rieker, Gregory B

    2010-12-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 ?F, 50 to 200 nH, and 1 to 3 kV, respectively. PMID:21267082

  4. Characteristics of impact-generated plasma with different electron temperature and gas temperature

    NASA Astrophysics Data System (ADS)

    Li, Jianqiao; Song, Weidong; Ning, Jianguo; Tang, Huiping

    2014-07-01

    The characteristics of the plasma with difference between the electron temperature and gas temperature were investigated and the relationship between the plasma ionization degree and the internal energy of a system was obtained. A group of equations included the chemical reaction equilibrium equation, the chemical reaction rate equation and the energy conservation equation were adopted to calculate the electron density, the electron temperature and the atom temperature with a given internal energy. These equations combined with Navier-Stokes (N-S) equations is solved by a smooth particle hydrodynamic (SPH) code. The charges generated in hypervelocity impacts with five different velocities are calculated and verified with the empirical formulas. The influence of a critical velocity for plasma generation is considered in the empirical formula and the parameters are fitted by the numerical results. By comparing with the results in reference, the fitted new empirical formula is verified to be reasonable and useful for a wide range of impact velocity.

  5. Effects of gas pressure on 60/13.56 MHz dual-frequency capacitively coupled plasmas

    SciTech Connect

    Yuan, Q. H.; Yin, G. Q. [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Xin, Y.; Ning, Z. Y. [School of Physical Science and Technology, Suzhou University, SuZhou 215006 (China)

    2011-05-15

    The electron energy probability functions (EEPFs) were measured with increasing gas pressure in 60/13.56 MHz dual-frequency capacitively coupled plasma (DF-CCP) using compensated Langmiur electrostatic probe. The transition pressure of heating mode from collisionless to collisional heating in 60/13.56 MHz DF-CCP is found to be significantly lower than that in 13.56 MHz single-frequency CCP. As the pressure increases, the EEPFs change from bi-Maxwellian to Druyvesteyn type which is similar with that in 60 MHz single-frequency CCP. The pressure dependence of electron densities, effective electron temperatures, floating potentials, and plasma potentials in 60/13.56 MHz DF-CCP were measured and were compared with that in 60 MHz single-frequency CCP. The pressure dependence of these plasma parameters in 60/13.56 MHz DF-CCP is similar with that in 60 MHz single-frequency CCP.

  6. 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

  7. DC-Pulsed Plasma for Dry Reforming of Methane to Synthesis Gas

    Microsoft Academic Search

    Naser Seyed-MatinAmir; Amir Hossein Jalili; Masih Hosseini Jenab; Seyed Majid Zekordi; Ali Afzali; Chapar Rasouli; Akbar Zamaniyan

    2010-01-01

    The carbon dioxide reforming of methane to synthesis gas under DC-pulsed plasma was investigated. The effects of specific\\u000a input energy and feed ratio on the product distribution and also feed conversion was studied. At the input energy of about\\u000a 11 eV\\/molecule per methane and\\/or carbon dioxide the feed conversion of 38% for CH4 and 28% for CO2 and product selectivity of

  8. Gas Chromatography-Inductively Coupled Plasma-Mass Spectrometry for Mercury Speciation in Seafood

    Microsoft Academic Search

    Yan LI; Shu-Juan LIU; Dong-Qing JIANG; Yan JIANG; Xiu-Ping YAN

    2008-01-01

    A method for mercury speciation in seafood was designed by on-line coupling gas chromatography (GC) to inductively coupled plasma mass spectrometry (ICP-MS) with an improved interface. The detection limits (S\\/N = 3) of methylmercury (MeHg(I)) and ethylmercury (EtHg(I)) were 0.5 pg and 1.0 pg (as Hg), respectively. The quantitative limits (S\\/N = 8) were 1.5 pg and 2.8 pg for

  9. Investigations on plasma-polymer-coated SAW and STW resonators for chemical gas-sensing applications

    Microsoft Academic Search

    Ivan D. Avramov; Shigeru Kurosawa; Michael Rapp; Piotr Krawczak; Ekaterina I. Radeva

    2001-01-01

    Results from gas probing with various analyte vapors on high-Q low-loss surface transverse wave (STW) and surface acoustic wave (SAW) resonators coated with thin plasma-polymer films of hexamethyldisiloxane (HMDSO), styrene, and allyl alcohol at different polymerization conditions are presented in this paper. At the same acoustic wavelength of 7.22 ?m and identical film thicknesses, HMDSO-coated STW devices feature substantially higher

  10. Plasma polymer thin film depositions to regulate gas permeability through nanoporous track etched membranes

    Microsoft Academic Search

    Christopher L. Chapman; Dhiman Bhattacharyya; Robert C. Eberhart; Richard B. Timmons; Cheng-Jen Chuong

    2008-01-01

    Deposition of thin polymeric films on nanoporous membranes is shown to provide a mechanically simple and inexpensive approach to regulate trans-membrane gas flows. For this purpose, polymeric films were deposited on polycarbonate track-etched (PCTE) membranes of 50nm and 100nm pore size. The films were generated by low-pressure glow discharge plasma polymerization of vinyl acetic acid (CH2CHCH2COOH) or perfluorohexane (n-C6F14) monomers.

  11. Characterization of gas targets for laser produced extreme ultraviolet plasmas with a Hartmann-Shack sensor

    SciTech Connect

    Peth, Christian; Kranzusch, Sebastian; Mann, Klaus; Vioel, Wolfgang [Laser-Laboratorium Goettingen e. V., Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen (Germany); Fachhochschule Hildesheim/Holzminden/Goettingen, Fakultaet Naturwissenschaften und Technik, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany)

    2004-10-01

    A table top extreme ultraviolet (EUV)-source was developed at Laser-Laboratorium Goettingen for the characterization of optical components and sensoric devices in the wavelength region from 11 to 13 nm. EUV radiation is generated by focusing the beam of a Q-switched Nd:YAG laser into a pulsed xenon gas jet. Since a directed gas jet with a high number density is needed for an optimal performance of the source, conical nozzles with different cone angles were drilled with an excimer laser to produce a supersonic gas jet. The influence of the nozzle geometry on the gas jet was characterized with a Hartmann-Shack wave front sensor. The deformation of a planar wave front after passing the gas jet was analyzed with this sensor, allowing a reconstruction of the gas density distribution. Thus, the gas jet was optimized resulting in an increase of EUV emission by a factor of two and a decrease of the plasma size at the same time.

  12. Amino acid (GAS:BCAA) ratios in plasma and gut contents of short-term protein depleted rats.

    PubMed

    Suzi?, S; Radunovi?, L J; Jankovi?, V; Segovi?, R

    1990-01-01

    The ratio of total concentrations or molar ratios (moles/1,000 amino acid residues) of three non-essential amino acids (glycine, alanine, serine-GAS) and three essential-branched chain amino acids (valine, isoleucine, leucine-BCAA) were investigated in rat systemic and portal vein plasma and jejunal and ileal gut contents after feeding normoprotein (NP) or protein-free (PF) diets for 7 days. Amino acid analysis of gut content showed that the GAS:BCAA ratio was not significantly altered by the PF diet either in the jejunum or in the ileum. On the contrary, the PF diet, caused a three and four-fold increase in this ratio in the portal and systemic plasma, respectively. The situation was produced by the higher concentrations of GAS, which remained near control levels (portal plasma) or exceeded these values (systemic plasma), in contrast to the decreasing levels of BCAA found in both plasmas of the PF group. PMID:2103638

  13. Note: Design and investigation of a multichannel plasma-jet triggered gas switch.

    PubMed

    Tie, Weihao; Liu, Xuandong; Zhang, Qiaogen; Liu, Shanhong

    2014-07-01

    We described the fabrication and testing of a multichannel plasma-jet triggered gas switch (MPJTGS). A novel six-channel annular micro-plasma-gun was embedded in the trigger electrode to generate multichannel plasma jets as a nanosecond trigger pulse arrived. The gas breakdown in multiple sites of the spark gap was induced and fixed around jet orifices by the plasma jets. We tested the multichannel discharge characteristics of the MPJTGS in two working modes with charge voltage of 50 kV, trigger voltage of +40 kV (25 ns rise time), and trigger energy of 240 J, 32 J, and 2 J, respectively, at different working coefficients. Results show that the average number of discharge channels increased as the trigger energy increased, and decreased as the working coefficient decreased. At a working coefficient of 87.1% and trigger energy of 240 J, the average number of discharge channels in Mode II could reach 4.1. PMID:25085190

  14. Direct evidence of mismatching effect on H emission in laser-induced atmospheric helium gas plasma

    NASA Astrophysics Data System (ADS)

    Sukra Lie, Zener; On Tjia, May; Hedwig, Rinda; Margaretha Suliyanti, Maria; Nur Abdulmadjid, Syahrun; Idris, Nasrullah; Mangasi Marpaung, Alion; Pardede, Marincan; Jobiliong, Eric; Ramli, Muliadi; Suyanto, Heri; Fukumoto, Kenichi; Kagawa, Kiichiro; Hendrik Kurniawan, Koo

    2013-02-01

    A time-resolved orthogonal double pulse laser-induced breakdown spectroscopy (LIBS) with helium surrounding gas is developed for the explicit demonstration of time mismatch between the passage of fast moving impurity hydrogen atoms and the formation of thermal shock wave plasma generated by the relatively slow moving major host atoms of much greater masses ablated from the same sample. Although this so-called "mismatching effect" has been consistently shown to be responsible for the gas pressure induced intensity diminution of hydrogen emission in a number of LIBS measurements using different ambient gases, its explicit demonstration has yet to be reported. The previously reported helium assisted excitation process has made possible the use of surrounding helium gas in our experimental set-up for showing that the ablated hydrogen atoms indeed move faster than the simultaneously ablated much heavier major host atoms as signaled by the earlier H emission in the helium plasma generated by a separate laser prior to the laser ablation. This conclusion is further substantiated by the observed dominant distribution of H atoms in the forward cone-shaped target plasma.

  15. Direct evidence of mismatching effect on H emission in laser-induced atmospheric helium gas plasma

    SciTech Connect

    Zener Sukra Lie; Koo Hendrik Kurniawan [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); May On Tjia [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia); Rinda, Hedwig [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Suliyanti, Maria Margaretha [Research Center for Physics, Indonesia Institute of Sciences, Kawasan PUSPIPTEK, Serpong, Tangerang Selatan 15314, Banten (Indonesia); Syahrun Nur Abdulmadjid; Nasrullah Idris [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Alion Mangasi Marpaung [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, Rawamangun, Jakarta 12440 (Indonesia); Marincan Pardede [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Jobiliong, Eric [Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Muliadi Ramli [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Heri Suyanto [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Fukumoto, Kenichi; Kagawa, Kiichiro [Research Institute of Nuclear Engineering, University of Fukui, Fukui 910-8507 (Japan)

    2013-02-07

    A time-resolved orthogonal double pulse laser-induced breakdown spectroscopy (LIBS) with helium surrounding gas is developed for the explicit demonstration of time mismatch between the passage of fast moving impurity hydrogen atoms and the formation of thermal shock wave plasma generated by the relatively slow moving major host atoms of much greater masses ablated from the same sample. Although this so-called 'mismatching effect' has been consistently shown to be responsible for the gas pressure induced intensity diminution of hydrogen emission in a number of LIBS measurements using different ambient gases, its explicit demonstration has yet to be reported. The previously reported helium assisted excitation process has made possible the use of surrounding helium gas in our experimental set-up for showing that the ablated hydrogen atoms indeed move faster than the simultaneously ablated much heavier major host atoms as signaled by the earlier H emission in the helium plasma generated by a separate laser prior to the laser ablation. This conclusion is further substantiated by the observed dominant distribution of H atoms in the forward cone-shaped target plasma.

  16. Measurement of resonance level densities in rare gas plasmas and modeling of their resulting VUV emissions

    NASA Astrophysics Data System (ADS)

    Boffard, J. B.; Culver, C. L.; Wang, S.; Lin, C. C.; Wendt, A. E.; Radovanov, S. B.; Persing, H. M.

    2013-09-01

    In the rare gases, the vacuum ultraviolet (VUV) emissions are dominated by the decays from the 1s2 and 1s4 (Paschen's notation) principal resonance levels. In isolation, atoms excited to these resonance levels have a short radiative lifetime (< 10 ns), but resonance blockade of the VUV transitions to the ground state significantly extend the effective lifetimes of these levels under typical plasma conditions with pressures greater than a mTorr. Despite this re-absorption, rare gas plasmas do produce copious VUV emissions that may play an important role in critical surface reactions under certain process conditions. We have measured the resonance level densities as a function of pressure in rare-gas discharges (Ne,Ar,Kr,Xe) in an inductively coupled plasma using both white-light absorption spectroscopy and optical emission spectroscopy by monitoring changes in the 2px --> 1sy branching fractions. The measured resonance level concentrations are subsequently used as inputs to a simple VUV transport model to determine the VUV flux to surfaces. These model VUV flux calculations are compared to measurements made with an absolutely calibrated VUV photodiode. In the rare gases, the vacuum ultraviolet (VUV) emissions are dominated by the decays from the 1s2 and 1s4 (Paschen's notation) principal resonance levels. In isolation, atoms excited to these resonance levels have a short radiative lifetime (< 10 ns), but resonance blockade of the VUV transitions to the ground state significantly extend the effective lifetimes of these levels under typical plasma conditions with pressures greater than a mTorr. Despite this re-absorption, rare gas plasmas do produce copious VUV emissions that may play an important role in critical surface reactions under certain process conditions. We have measured the resonance level densities as a function of pressure in rare-gas discharges (Ne,Ar,Kr,Xe) in an inductively coupled plasma using both white-light absorption spectroscopy and optical emission spectroscopy by monitoring changes in the 2px --> 1sy branching fractions. The measured resonance level concentrations are subsequently used as inputs to a simple VUV transport model to determine the VUV flux to surfaces. These model VUV flux calculations are compared to measurements made with an absolutely calibrated VUV photodiode. This work was supported in part by NSF grant PHY-1068670.

  17. Identification of the most efficient VUV\\/UV radiation for plasma based inactivation of Bacillus atrophaeus spores

    Microsoft Academic Search

    H. Halfmann; B. Denis; N. Bibinov; J. Wunderlich; P. Awakowicz

    2007-01-01

    The identification of sterilization agents is mandatory to achieve sterilization mechanisms in low-pressure discharges. A detailed account of each agent is required for improvements, development and establishment of plasma sterilization as an alternative to traditional sterilization processes. Sterilization agents are VUV and UV radiation, photodesorption producing volatile species and etching of spore coat and membrane. This work focuses on VUV

  18. Generation of soft X rays using a rare gas-hydrogen plasma focus and its application to X-ray lithography

    Microsoft Academic Search

    Y. Kato; S. H. Be

    1986-01-01

    A conventional plasma focus device was used to produce a hot, dense plasma which emits radiation strongly in the soft X-ray region. It was shown experimentally that a plasma produced from a mixture of hydrogen and a rare gas such as neon, argon, or krypton is an effective source of a characteristic X-ray of the rare gas. Resist exposures and

  19. 21 CFR 880.6880 - Steam sterilizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 2014-04-01 false Steam sterilizer. 880.6880 Section 880.6880...Personal Use Miscellaneous Devices § 880.6880 Steam sterilizer. (a) Identification. A steam sterilizer (autoclave) is a device...

  20. 21 CFR 880.6880 - Steam sterilizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 2011-04-01 false Steam sterilizer. 880.6880 Section 880.6880...Personal Use Miscellaneous Devices § 880.6880 Steam sterilizer. (a) Identification. A steam sterilizer (autoclave) is a device...

  1. 21 CFR 880.6880 - Steam sterilizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 2013-04-01 false Steam sterilizer. 880.6880 Section 880.6880...Personal Use Miscellaneous Devices § 880.6880 Steam sterilizer. (a) Identification. A steam sterilizer (autoclave) is a device...

  2. 21 CFR 880.6880 - Steam sterilizer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 2012-04-01 false Steam sterilizer. 880.6880 Section 880.6880...Personal Use Miscellaneous Devices § 880.6880 Steam sterilizer. (a) Identification. A steam sterilizer (autoclave) is a device...

  3. 21 CFR 880.6880 - Steam sterilizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 2010-04-01 2010-04-01 false Steam sterilizer. 880.6880 Section 880.6880...Personal Use Miscellaneous Devices § 880.6880 Steam sterilizer. (a) Identification. A steam sterilizer (autoclave) is a device...

  4. Gas to particle conversion-gas exchange technique for direct analysis of metal carbonyl gas by inductively coupled plasma mass spectrometry.

    PubMed

    Nishiguchi, Kohei; Utani, Keisuke; Gunther, Detlef; Ohata, Masaki

    2014-10-21

    A novel gas to particle conversion-gas exchange technique for the direct analysis of metal carbonyl gas by inductively coupled plasma mass spectrometry (ICPMS) was proposed and demonstrated in the present study. The technique is based on a transfer of gas into particle, which can be directly analyzed by ICPMS. Particles from metal carbonyl gases such as Cr(CO)6, Mo(CO)6, and W(CO)6 are formed by reaction with ozone (O3) and ammonium (NH3) gases within a newly developed gas to particle conversion device (GPD). The reaction mechanism of the gas to particle conversion is based on either oxidation of metal carbonyl gas by O3 or agglomeration of metal oxide with ammonium nitrate (NH4NO3) which is generated by the reaction of O3 and NH3. To separate the reaction gases (remaining O3 and NH3) from the formed particles, a previously reported gas exchange device (GED) was used and the in argon stabilized analyte particles were directly introduced and measured by ICPMS. This new technique provided limits of detection (LOD) of 0.15 pL L(-1) (0.32 ng m(-3)), 0.02 pL L(-1) (0.07 ng m(-3)), and 0.01 pL L(-1) (0.07 ng m(-3)) for Cr(CO)6, Mo(CO)6, and W(CO)6, respectively, which were 4-5 orders of magnitude lower than those conventional applied for detecting these gases, e.g., gas chromatography with electron captured detector (GC-ECD) as well as Fourier transform-infrared spectroscopy (FT-IR). The achieved LODs were also similar or slightly better than those for ICPMS coupled to GC. Since the gas to particle conversion technique can achieve the direct measurement of metal carbonyl gases as well as the removal of reaction and ambient gases from metal carbonyl gases, the technique is considered to be well suited to monitor gas quality in semiconductor industry, engine exhaust gases, and or waste incineration products. PMID:25247610

  5. Routine analysis of plasma busulfan by gas chromatography-mass fragmentography.

    PubMed

    Lai, W K; Pang, C P; Law, L K; Wong, R; Li, C K; Yuen, P M

    1998-12-01

    Busulfan (BU) is a widely used alkylating agent for antineoplastic therapy and marrow ablation in preparation for bone marrow transplantation (BMT). High-dose BU often leads to successful preparation and low relapse but is associated with veno-occlusive disease of liver. We established a protocol to determine postdosage plasma BU concentrations by gas chromatography-mass fragmentography in an attempt to relate clinical outcome to plasma BU concentrations. We used nonisotopic pusulfan as the internal standard. After extraction into ethyl acetate, BU and pusulfan were iodinated into 1, 4-diiodobutane and 1,5-diiodopentane, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out on an Hewlett-Packard (HP) 5890II gas chromatograph with a 30-m 100% methyl silicon narrow bore, fused-silica capillary column interfaced with an HP 5970A mass spectrometer. Helium was the carrier gas. The sample molecules were identified by total ion monitoring and quantified by selective ion monitoring of m/z 183 and 197. The calibration curve was linear to 4 mg/L. The limit of quantification was 0.04 mg/L, and the analytical recovery was approximately 97%. The within-day and between-day imprecision (CV) was <6% and 9%, respectively. In a preliminary study of 12 children, the BU areas under the BU-time curve were 616-949 micromol. min/L after the first dose and 793-1143 micromol. min/L after the fifth dose. We conclude that the GC-MS procedure is suitable for routine analysis of plasma BU. PMID:9836718

  6. Effect of ambient gas pressure and nature on the temporal evolution of aluminum laser-induced plasmas

    NASA Astrophysics Data System (ADS)

    Dawood, M. S.; Margot, Joëlle

    2014-03-01

    Time-resolved analysis of emission spectra, electron densities and excitation temperatures of Aluminum laser induced plasmas produced in argon, nitrogen and helium at different pressures have been studied experimentally. The plasma emission intensity is found to be strongly affected by the plume confinement and differs with the nature of the ambient gas and its pressure. Our observations show that both electron density and excitation temperature increase with the ambient gas pressure. In addition, Argon was found to produce the highest plasma density and temperature and Helium the lowest, while Nitrogen yields intermediate values.

  7. The influence of surface patterning and\\/or sterilization on the haemocompatibility of polycaprolactones

    Microsoft Academic Search

    M. Stavridi; M. Katsikogianni; Y. F. Missirlis

    2003-01-01

    Platelet adhesion, coagulation and complement activation of flowing human blood over flat, nanostructured, sterilized or not sterilized surfaces of polycaprolactones (PCL) has been attempted. Two PCL samples were secured in place forming a parallel plate flow chamber. Platelet-poor plasma (PPP) or platelet-rich plasma (PRP) circulated for 30 min with a flow rate of 22 ml\\/min. The PPP was then collected

  8. Low Temperature Plasma Medicine

    NASA Astrophysics Data System (ADS)

    Graves, David

    2013-10-01

    Ionized gas plasmas near room temperature are used in a remarkable number of technological applications mainly because they are extraordinarily efficient at exploiting electrical power for useful chemical and material transformations near room temperature. In this tutorial address, I will focus on the newest area of low temperature ionized gas plasmas (LTP), in this case operating under atmospheric pressure conditions, in which the temperature-sensitive material is living tissue. LTP research directed towards biomedical applications such as sterilization, surgery, wound healing and anti-cancer therapy has seen remarkable growth in the last 3-5 years, but the mechanisms responsible for the biomedical effects have remained mysterious. It is known that LTP readily create reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS (or RONS), in addition to a suite of other radical and non-radical reactive species, are essential actors in an important sub-field of aerobic biology termed ``redox'' (or oxidation-reduction) biology. I will review the evidence suggesting that RONS generated by plasmas are responsible for their observed therapeutic effects. Other possible bio-active mechanisms include electric fields, charges and photons. It is common in LTP applications that synergies between different mechanisms can play a role and I will review the evidence for synergies in plasma biomedicine. Finally, I will address the challenges and opportunities for plasma physicists to enter this novel, multidisciplinary field.

  9. Thin film growth from a low pressure plasma excited in a supersonic expanding gas jet

    NASA Astrophysics Data System (ADS)

    Wachtendorf, C.; Herweg, C.; Daeuber, M.; Benedikt, J.; von Keudell, A.

    2009-05-01

    A gas jet from argon and tetramethylsilane mixtures is generated by supersonic expansion through a grounded tungsten capillary (inner diameter 600 µm). This jet expands into a low pressure region (p ~ 10 Pa) formed as an open tube (diameter 3 mm, variable length between 1 and 8 cm) in a stainless steel block. The steel block is biased by a pulsed kilohertz-signal generating a low pressure plasma. Due to the low pressure, a hollow cathode effect is observed depending on process parameters. 2D compressible flow simulations show a strong pressure gradient of several hundred pascals inside the open tube, with a low pressure zone at the exit of the gas jet and a high pressure zone in the centre of the open tube. The deposition profiles, deduced from optical film thickness measurements for different tube lengths, are discussed. The dependence of the breakdown voltage and of the differential resistance on the process parameters can be consistently explained by Paschen's law. The effective pressure allowing plasma ignition is at least a factor of 3 smaller than the average pressure inside the open tube, suggesting that pre-ionization in the supersonic expansion zone facilitates plasma ignition in the high pressure zone.

  10. Pulsed-plasma gas-discharge inactivation of microbial pathogens in chilled poultry wash water.

    PubMed

    Rowan, N J; Espie, S; Harrower, J; Anderson, J G; Marsili, L; MacGregor, S J

    2007-12-01

    A pulsed-plasma gas-discharge (PPGD) system was developed for the novel decontamination of chilled poultry wash water. Treatment of poultry wash water in the plasma generation chamber for up to 24 s at 4 degrees C reduced Escherichia coli NCTC 9001, Campylobacter jejuni ATCC 33560, Campylobacter coli ATCC 33559, Listeria monocytogenes NCTC 9863, Salmonella enterica serovar Enteritidis ATCC 4931, and S. enterica serovar Typhimurium ATCC 14028 populations to non-detectable levels (< or = 8 log CFU/ml). Although similar PPGD treatments at 4 degrees C also produced significant reductions (> or = 3 log CFU/ml) in recalcitrant B. cereus NCTC 11145 endospore numbers within 30 s, the level of endospore reduction was dependent on the nature of the sparged gas used in the plasma treatments. Scanning electron microscopy revealed that significant damage occurred at the cellular level in PPGD-treated test organisms. This electrotechnology delivers energy in intense ultrashort bursts, generating products such as ozone, UV light, acoustic and shock waves, and pulsed electric fields that have multiple bactericidal properties. This technology offers an exciting complementary or alternative approach for treating raw poultry wash water and for preventing cross-contamination in processing environments. PMID:18095434

  11. Emission spectroscopy of a microhollow cathode discharge plasma in helium-water gas mixtures

    SciTech Connect

    Namba, S.; Yamasaki, T.; Hane, Y.; Fukuhara, D.; Kozue, K.; Takiyama, K. [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan)

    2011-10-01

    A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to H{alpha} at 656.3 nm implied an electron density and gas temperature of 2 x 10{sup 14} cm{sup -3} and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and H{alpha} intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e{sup -}{yields} O + H + e{sup -}.

  12. Interplay between discharge physics, gas phase chemistry and surface processes in hydrocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Hassouni, Khaled

    2013-09-01

    In this paper we present two examples that illustrate two different contexts of the interplay between plasma-surface interaction process and discharge physics and gas phase chemistry in hydrocarbon discharges. In the first example we address the case of diamond deposition processes and illustrate how a detailed investigation of the discharge physics, collisional processes and transport phenomena in the plasma phase make possible to accurately predict the key local-parameters, i.e., species density at the growing substrate, as function of the macroscopic process parameters, thus allowing for a precise control of diamond deposition process. In the second example, we illustrate how the interaction between a rare gas pristine discharge and carbon (graphite) electrode induce a dramatic change on the discharge nature, i.e., composition, ionization kinetics, charge equilibrium, etc., through molecular growth and clustering processes, solid particle formation and dusty plasma generation. Work done in collaboration with Alix Gicquel, Francois Silva, Armelle Michau, Guillaume Lombardi, Xavier Bonnin, Xavier Duten, CNRS, Universite Paris 13.

  13. [Principles of antisepsis, disinfection and sterilization].

    PubMed

    Hernández-Navarrete, María-Jesús; Celorrio-Pascual, José-Miguel; Lapresta Moros, Carlos; Solano Bernad, Victor-Manuel

    2014-12-01

    This article aims to provide a brief review of the main concepts on which the prevention and control of infection are based. Antisepsis comprises a set of techniques aimed at the total sterilization, or at most, disinfection, removing germs that contaminate an environment. Both procedures must be preceded by an environmental cleanup in the location in which they intend to be applied. The disinfection is carried out using biocides or germicides. Antimicrobial chemicals, that have mechanisms of action and resistances very similar to antibiotics, are generating concern due to the possibility of crossing genetic information that aggravates the problem of bacterial resistance. Most biocides can act as antiseptics, and applied to skin tissue, or disinfectants on inanimate materials. The spectrum of action of germicides depends on the product itself and external controllable factors: temperature, concentration, exposure time, etc. Sterilization techniques are primarily physical, by exposing the material to steam, or sterilizing gas, using autoclaves. Major advances are the use of low temperatures with shorter exposure times, in parallel with technological advances in instrumentation in order to avoid high temperatures and high use rotations due to workload. PMID:25023372

  14. Gas monitoring in RPC by means of non-invasive plasma coated POF sensors

    NASA Astrophysics Data System (ADS)

    Grassini, S.; Ishtaiwi, M.; Parvis, M.; Benussi, L.; Bianco, S.; Colafranceschi, S.; Piccolo, D.

    2012-12-01

    Resistive Plate Counters (RPC) are employed as muon detectors in many high-rate high-energy physics experiments, such as the Compact Muon Solenoid (CMS) experiment currently under way in the Large Hadron Collider (LHC) accelerator at the European Center for Nuclear Research (CERN). A gas mixture containing C2H2F4, i-C4H10 and SF6 is recirculated inside the RPCs during their use and subjected to degradation due to the production of fluoride ions which limits the sensitivity of the RPCs. This paper describes a new sensor that is able to detect low concentrations of fluoride ions in gas mixtures. The sensor is made of a plastic optic fiber (POF) which is made sensitive to F- gaseous ions by means of a thin layer of a glass-\\it likematerial, deposited via plasma onto the fiber core. The F- ions attack the glass-\\it likefilm and alter the transmission capability of the fiber so that the detection simply requires a LED and a photodiode. The sensor exploits a cumulative response which makes it suitable for direct estimation of the total exposure to the F- ions, thus providing a tool that can be used to tune the maintenance of the gas filters. The glass-\\it likefilm is deposited by means of plasma enhanced chemical vapor deposition (PECVD) of organosilicons monomers, which allows the deposition to be performed a low temperature in order to avoid damaging the fiber core.

  15. Controlling the Neutron Yield from a Small Dense Plasma Focus using Deuterium-Inert Gas Mixtures

    SciTech Connect

    Bures, B. L.; Krishnan, M.; Eshaq, Y. [Alameda Applied Sciences Corp. 626 Whitney St., San Leandro, CA (United States)

    2009-01-21

    The dense plasma focus (DPF) is a well known source of neutrons when operating with deuterium. The DPF is demonstrated to scale from 10{sup 4} n/pulse at 40 kA to >10{sup 12} n/pulse at 2 MA by non-linear current scaling as described in [1], which is itself based on the simple yet elegant model developed by Lee [2]. In addition to the peak current, the gas pressure controls the neutron yield. Recent published results suggest that mixing 1-5% mass fractions of Krypton increase the neutron yield per pulse by more than 10x. In this paper we present results obtained by mixing deuterium with Helium, Neon and Argon in a 500 J dense plasma focus operating at 140 kA with a 600 ns rise time. The mass density was held constant in these experiments at the optimum (pure) deuterium mass density for producing neutrons. A typical neutron yield for a pure deuterium gas charge is 2x10{sup 6}{+-}15% n/pulse. Neutron yields in excess of 10{sup 7}{+-}10% n/pulse were observed with low mass fractions of inert gas. Time integrated optical images of the pinch, soft x-ray measurements and optical emission spectroscopy where used to examine the pinch in addition to the neutron yield monitor and the fast scintillation detector. Work supported by Domestic Nuclear Detection Office under contract HSHQDC-08-C-00020.

  16. Direct measurement of coherent ultrahigh wakefields excited by intense ultrashort laser pulses in a gas-jet plasma

    Microsoft Academic Search

    Hideyuki Kotaki; Masaki Kando; Takatsugu Oketa; Shinichi Masuda; James K. Koga; Shuji Kondo; Shuhei Kanazawa; Takashi Yokoyama; Toru Matoba; Kazuhisa Nakajima

    2002-01-01

    The coherent wakefield excited by 2 TW, 50 fs laser pulses in a gas-jet plasma around 1018 cm-3 is measured with a time-resolved frequency domain interferometer. The density distribution of the helium gas is measured with a time-resolved Mach-Zehnder interferometer to search for the optimum laser focus position and timing in the gas jet. The results show an accelerating wakefield

  17. Plasma structures observed in gas breakdown using a 1.5 MW, 110 GHz pulsed gyrotrona)

    NASA Astrophysics Data System (ADS)

    Hidaka, Yoshiteru; Choi, E. M.; Mastovsky, I.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.; Edmiston, G. F.; Neuber, A. A.; Oda, Y.

    2009-05-01

    Regular two-dimensional plasma filamentary arrays have been observed in gas breakdown experiments using a pulsed 1.5 MW, 110 GHz gyrotron. The gyrotron Gaussian output beam is focused to an intensity of up to 4 MW/cm2. The plasma filaments develop in an array with a spacing of about one quarter wavelength, elongated in the electric field direction. The array was imaged using photodiodes, a slow camera, which captures the entire breakdown event, and a fast camera with a 6 ns window. These diagnostics demonstrate the sequential development of the array propagating back toward the source. Gases studied included air, nitrogen, SF6, and helium at various pressures. A discrete plasma array structure is observed at high pressure, while a diffuse plasma is observed at lower pressure. The propagation speed of the ionization front for air and nitrogen at atmospheric pressure for 3 MW/cm2 was found to be of the order of 10 km/s.

  18. Gas Chemistry Dependence of Si Surface Reactions in a Fluorocarbon Plasma during Contact Hole Etching

    NASA Astrophysics Data System (ADS)

    Komeda, Hiroyuki; Ueda, Tohru; Wada, Sakae; Ohmi, Tadahiro

    1998-03-01

    Gas chemistry dependence of Si surface reactions in a high C/F ratio fluorocarbon plasma during contact hole etching was investigated. CO and C4F8 were selected as additional gases for CF4/CHF3/Ar chemistry. CO addition increased the neutral carbon density in the plasma, C4F8 addition increased not only the fluorocarbon radicals but also the fluorocarbon ion flux. Although both gases enhanced the deposition rate of the fluorocarbon film on the Si surface, there is a difference in the mechanism of the film deposition. CO addition increased the radical sticking site in the fluorocarbon film deposited on the Si surface due to an abundant carbon density in the plasma. C4F8 addition increased the precursor radical density in the plasma due to the electron impact dissociation of C4F8. Since damage formation depends on the fluorocarbon ion flux, increasing of the fluorocarbon ion flux by C4F8 addition enhanced the damage formation.

  19. Specific estimation of 24,25-dihydroxyvitamin D in plasma by gas chromatography-mass spectrometry.

    PubMed

    Coldwell, R D; Trafford, D J; Makin, H L; Varley, M J; Kirk, D N

    1984-07-01

    This paper describes a specific mass-fragmentographic method, involving a stable-isotope-labeled internal standard, for measurement of 24,25-dihydroxyvitamin D in human plasma. Vitamin D metabolites were rapidly extracted from plasma by using Sep-Pak C18 cartridges and separated into fractions on Sep-Pak SIL cartridges. The polar fraction, containing the dihydroxylated metabolites, was further purified by "high-performance" liquid chromatography on Zorbax SIL. The fraction containing 24,25-dihydroxyvitamin D was collected, evaporated, and converted to the 24:25-cyclic n-butyl boronate-3-trimethylsilyl ether derivative before analysis by gas chromatography-mass spectrometry. The intensity of the mass fragment (m/z 449, m/z 455 for the hexadeuterated internal standard) arising from the loss of one of the angular methyls and the 3-silanol group [( M-90-15]+) was monitored. The minimum limit of detection for this method is about 0.1 microgram/L. Inter- and intra-assay reproducibility was acceptable, and analytical recovery of added 24,25-dihydroxyvitamin D3 over the concentration range 1.0 to 5.0 micrograms/L was quantitative. Concentrations of 24,25-dihydroxyvitamin D3 in plasma of 21 apparently healthy volunteers were between 0.55 and 5.39 micrograms/L, higher values being obtained after prolonged exposure to the sun. No 24,25-dihydroxyvitamin D2 could be detected in any plasma sample examined. PMID:6610503

  20. Sequelae of postpartum sterilization.

    PubMed

    Rosenfeld, B L; Taskin, O; Kafkashli, A; Rosenfeld, M L; Chuong, C J

    1998-01-01

    This study was designed to investigate the menstrual, psychosexual, psychological and somatic sequelae in a group of women who may be more prone to express regret following postpartum sterilization. The follow-up was conducted by questionnaire at six months and five years following the procedure. Data were available from 242 patient; 76.8% were below the age of 30. Of all patients, 21.9% expressed regrets. About one third had various menstrual disturbances. Patients rated their sex life as generally more enjoyable in many aspects. The most common psychological symptoms were irritability, nervousness and depression; while the common somatic symptoms were pelvic/abdominal pain and backache and tiredness. PMID:9789648

  1. Sterile Inflammation in Drosophila

    PubMed Central

    Shaukat, Zeeshan; Liu, Dawei; Gregory, Stephen

    2015-01-01

    The study of immune responses in Drosophila has already yielded significant results with impacts on our understanding of vertebrate immunity, such as the characterization of the Toll receptor. Several recent papers have focused on the humoral response to damage signals rather than pathogens, particularly damage signals from tumour-like tissues generated by loss of cell polarity or chromosomal instability. Both the triggers that generate this sterile inflammation and the systemic and local effects of it are only just beginning to be characterized in Drosophila. Here we review the molecular mechanisms that are known that give rise to the recruitment of Drosophila phagocytes, called hemocytes, as well as the signals, such as TNF?, that stimulated hemocytes emit at sites of perceived damage. The signalling consequences of inflammation, such as the activation of JNK, and the potential for modifying this response are also discussed. PMID:25948885

  2. Instabilities in uranium plasma and the gas-core nuclear rocket engine

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1972-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P approximates 0.00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  3. Quantification of clotiazepam in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Ahn, Sung-Hoon; Maeng, Han-Joo; Koo, Tae-Sung; Kim, Dae-Duk; Shim, Chang-Koo; Chung, Suk-Jae

    2006-04-13

    An analytical procedure was developed and validated for the quantification of clotiazepam in human plasma. After subjecting plasma samples to solid-phase extraction, the extract was evaporated and the residue re-constituted. An aliquot of the mixture was injected onto a gas chromatography-mass spectrometry system. The detector response was linear for clotiazepam concentrations in the range of 5-200 ng/ml. Intra- and inter-day precision for the assay over the concentration range was below 13.1 and 13.5%, and the accuracy ranged between 99.0-107.9% and 92.4-101.3%, respectively. The drug was found to be stable under various processing conditions used. The method is applicable to human pharmacokinetic studies of clotiazepam. PMID:16517222

  4. Size-selected cluster beam source based on radio frequency magnetron plasma sputtering and gas condensation

    SciTech Connect

    Pratontep, S.; Carroll, S.J.; Xirouchaki, C.; Streun, M.; Palmer, R.E. [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2005-04-01

    We report on a source for producing size-selected nanoclusters based on the combination of radio frequency magnetron plasma sputtering and gas condensation. The use of plasma sputtering to vaporize a target is applicable to a large range of materials; Ag, Au, Cu, and Si have been attempted to date. The source, combined with a time-of-flight mass filter, can produce clusters in the size range from 2 up to at least 70 000 atoms, depending on the target material, with a constant mass (M) resolution (M/{delta}M{approx}25) at an intensity that produces atomic monolayer coverage in as little as a few minutes. The source is also attached to an ultrahigh vacuum analysis chamber, which allows in situ surface chemical and structural analysis. Examples of cluster deposition experiments with the source are also presented.

  5. Manufacturing of size controlled a-Si:H nanoparticles in plasma using pulsed hydrogen gas.

    PubMed

    Kim, Kwangsu; Park, Jinhwan; Doo, Seokgwang; Nam, Jaedo; Kim, Taesung

    2009-12-01

    We synthesized size controlled a-Si:H nanoparticles in plasma using a hydrogen gas pulse. An inductively-coupled plasma chamber with RF power (13.56 MHz) was designed for this study. Experiments were performed with various hydrogen pulse ON-times ranging between 0.1 to 0.9 seconds for 1 second periods. The size of the synthesized nanoparticles was measured and analyzed using electron microscopy, Scanning Mobility Particle Sizer (SMPS) and Image J software. We observed that the size of a-Si:H nanoparticles decreased when the hydrogen pulse ON-time was increased. The a-Si:H nanoparticles were found to be spherical in shape and uniform. For hydrogen pulse ON-time greater than 0.3 second, we observed agglomerated particles due to an increase in their concentration. We hope that these particles can be used as an alternative anode material for lithium ion secondary batteries. PMID:19908779

  6. Tunable narrow band THz wave generation from laser induced gas plasma.

    PubMed

    Das, Jayashis; Yamaguchi, Masashi

    2010-03-29

    Tunable narrowband THz waveforms were generated from laser induced gas plasma using shaped optical pulses. Square wave phase patterns were fed to a spatial light modulator. The frequency and amplitude of the square wave phase were used as parameters to tailor the terahertz waveforms. The dependence of THz waveforms on these parameters has been studied in detail. The presence of the ionization thresholds for pulse shaping is also discussed. We have demonstrated the wide and continuous tunability of the central frequency of the narrowband THz waveform from 2.5 to 7.5THz. PMID:20389724

  7. Plasma-sprayed zirconia gas path seal technology: A state-of-the-art review

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1979-01-01

    The benefits derived from application of ceramic materials to high pressure turbine gas path seal components are described and the developmental backgrounds of various approaches are reviewed. The most fully developed approaches are those employing plasma sprayed zirconium oxide as the ceramic material. Prevention of cracking and spalling of the zirconium oxide under cyclic thermal shock conditions imposed by the engine operating cycle is the most immediate problem to be solved before implementation is undertaken. Three promising approaches to improving cyclic thermal shock resistance are described and comparative rig performance of each are reviewed. Advanced concepts showing potential for performance improvements are described.

  8. Gas flow dependence of ground state atomic oxygen in plasma needle discharge at atmospheric pressure

    SciTech Connect

    Sakiyama, Yukinori; Graves, David B. [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Knake, Nikolas; Schroeder, Daniel; Winter, Joerg; Schulz-von der Gathen, Volker [Institut fuer Experimentalphysik II, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

    2010-10-11

    We present clear evidence that ground state atomic oxygen shows two patterns near a surface in the helium plasma needle discharge. Two-photon absorption laser-induced fluorescence spectroscopy, combined with gas flow simulation, was employed to obtain spatially-resolved ground state atomic oxygen densities. When the feed gas flow rate is low, the radial density peaks along the axis of the needle. At high flow rate, a ring-shaped density distribution appears. The peak density is on the order of 10{sup 21} m{sup -3} in both cases. The results are consistent with a previous report of the flow-dependent bacterial killing pattern observed under similar conditions.

  9. Ion Species and Charge States of Vacuum Arc Plasma with Gas Feed and Longitudinal Magnetic Field

    SciTech Connect

    Oks, Efim; Anders, Andre

    2010-06-23

    The evolution of copper ion species and charge state distributions is measured for a long vacuum arc discharge plasma operated in the presence of a longitudinal magnetic field of several 10 mT and working gas (Ar). It was found that changing the cathode-anode distance within 20 cm as well as increasing the gas pressure did not affect the arc burning voltage and power dissipation by much. In contrast, burning voltage and power dissipation were greatly increased as the magnetic field was increased. The longer the discharge gap the greater was the fraction of gaseous ions and the lower the fraction of metal ions, while the mean ion charge state was reduced. It is argued that the results are affected by charge exchange collisions and electron impact ionization.

  10. Detection of deuterium and hydrogen using laser-induced helium gas plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kurniawan, Koo Hendrik; Lie, Tjung Jie; Suliyanti, Maria Margaretha; Hedwig, Rinda; Abdulmadjid, Syahrun Nur; Pardede, Marincan; Idris, Nasrullah; Kobayashi, Takao; Kusumoto, Yoshihumi; Kagawa, Kiichiro; Tjia, May On

    2005-11-01

    An experimental study on gas analysis by means of laser-induced breakdown spectroscopy was conducted using a Nd-yttrium aluminum garnet laser (1,064 nm, 120 mJ, 8 ns) and helium host gas at atmospheric pressure on a sample of mixed water (H2O) and heavy water (D2O) in vapor form. It was shown that completely resolved hydrogen (H?) and deuterium (D?) emission lines that are separated by only 0.179 nm could be obtained at a properly delayed detection time when the charged particles responsible for the strong Stark broadening effect in the plasma have mostly disappeared. It is argued that the helium metastable excited state plays an important role in the hydrogen excitation process.

  11. Laser Wakefield Structures and Electron Acceleration in Gas Jet and Capillary Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Maksimchuk, Anatoly

    2007-11-01

    Laser-driven plasma wakefield accelerators have the potential to become the next generation of particle accelerators because of the very high acceleration gradients. The beam quality from such accelerators depends critically on the details plasma wave spatial structures. In experiments at the University of Michigan it was possible in a single shot by frequency domain holography (FDH) to visualize individual plasma waves produced by the 40 TW, 30 fs Hercules laser focused to the intensity of 10^19 W/cm^2 onto a supersonic He gas jet [1]. These holographic ``snapshots'' capture the evolution of multiple wake periods, and resolve wavefront curvature seen previously only in simulations. High-energy quasi-monoenergetic electron beams for plasma density in the specific range 1.5x10^19<=ne<=3.5x10^19 cm-3 were generated [2]. The experiments show that the energy, charge, divergence and pointing stability of the beam can be controlled by changing ne, and that higher electron energies and more stable beams are produced for lower densities. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne=1.5x10^19 cm-3. The resulted relativistic electron beams have been used to perform gamma-neutron activation of ^12C and ^63Cu and photo-fission of ^238U with a record high reaction yields of ˜5x10^5/Joule [3]. Experiments performed with ablative capillary discharge plasma demonstrate stable guiding for laser power up to 10 TW with the transmission of 50% and guided intensity of ˜10^17 W/cm^2. Study of the staged electron acceleration have been performed which uses ablated plasma in front of the capillary to inject electrons into the wakefield structures. [1] N. H. Matlis et. al., Nature Physics 2, 749 (2006). [2] A. Maksimchuk et. al., Journal de Physique IV 133, 1123 (2006). [3] S. A. Reed et. al., Appl. Phys. Lett. 89, 231107 (2006).

  12. Plasma density measurement in a gas-filled X-band backward wave oscillator with a double conversion heterodyne microwave interferometer

    NASA Astrophysics Data System (ADS)

    Zhai, Xiaoling; Garate, Eusebio; Prohaska, Robert; Benford, Gregory

    1996-02-01

    Plasma density was measured with a heterodyne microwave interferometer in both a gas-filled X-band backward wave oscillator (BWO) and in a smooth tube. Plasma is generated by impact ionization of a 650 kV, 2 kA electron beam. For fixed gas pressure we found that the plasma density rise in the operating BWO was much faster than in a smooth tube, indicating that Trivelpiece-Gould modes, or high power microwaves, increase plasma generation. Additional plasma enhanced BWO microwave output power. Measured plasma density at optimum power levels was ncr ? 6 × 10 12cm -3 at onset of emitted microwaves.

  13. Persistent Effectivity of Gas Plasma-Treated, Long Time-Stored Liquid on Epithelial Cell Adhesion Capacity and Membrane Morphology

    PubMed Central

    Hoentsch, Maxi; Bussiahn, René; Rebl, Henrike; Bergemann, Claudia; Eggert, Martin; Frank, Marcus; von Woedtke, Thomas; Nebe, Barbara

    2014-01-01

    Research in plasma medicine includes a major interest in understanding gas plasma-cell interactions. The immediate application of gas plasma in vitro inhibits cell attachment, vitality and cell-cell contacts via the liquid. Interestingly, in our novel experiments described here we found that the liquid-mediated plasma effect is long-lasting after storage up to seven days; i. e. the liquid preserves the characteristics once induced by the argon plasma. Therefore, the complete Dulbecco's Modified Eagle cell culture medium was argon plasma-treated (atmospheric pressure, kINPen09) for 60 s, stored for several days (1, 4 and 7 d) at 37°C and added to a confluent mouse hepatocyte epithelial cell (mHepR1) monolayer. Impaired tight junction architecture as well as shortened microvilli on the cell membrane could be observed, which was accompanied by the loss of cell adhesion capacity. Online-monitoring of vital cells revealed a reduced cell respiration. Our first time-dependent analysis of plasma-treated medium revealed that temperature, hydrogen peroxide production, pH and oxygen content can be excluded as initiators of cell physiological and morphological changes. The here observed persisting biological effects in plasma-treated liquids could open new medical applications in dentistry and orthopaedics. PMID:25170906

  14. Development of a plasma sprayed ceramic gas path seal for high pressure turbine applications

    NASA Technical Reports Server (NTRS)

    Shiembob, L. T.

    1977-01-01

    The plasma sprayed graded layered yittria stabilized zirconia (ZrO2)/metal(CoCrAlY) seal system for gas turbine blade tip applications up to 1589 K (2400 F) seal temperatures was studied. Abradability, erosion, and thermal fatigue characteristics of the graded layered system were evaluated by rig tests. Satisfactory abradability and erosion resistance was demonstrated. Encouraging thermal fatigue tolerance was shown. Initial properties for the plasma sprayed materials in the graded, layered seal system was obtained, and thermal stress analyses were performed. Sprayed residual stresses were determined. Thermal stability of the sprayed layer materials was evaluated at estimated maximum operating temperatures in each layer. Anisotropic behavior in the layer thickness direction was demonstrated by all layers. Residual stresses and thermal stability effects were not included in the analyses. Analytical results correlated reasonably well with results of the thermal fatigue tests. Analytical application of the seal system to a typical gas turbine engine application predicted performance similar to rig specimen thermal fatigue performance. A model for predicting crack propagation in the sprayed ZrO2/CoCrAlY seal system was proposed, and recommendations for improving thermal fatigue resistance were made. Seal system layer thicknesses were analytically optimized to minimize thermal stresses in the abradability specimen during thermal fatigue testing. Rig tests on the optimized seal configuration demonstrated some improvement in thermal fatigue characteristics.

  15. Plasma-weld pool interaction in tungsten inert-gas configuration

    NASA Astrophysics Data System (ADS)

    Mougenot, J.; Gonzalez, J.-J.; Freton, P.; Masquère, M.

    2013-04-01

    A three-dimensional (3D) transient model of a transferred argon arc in interaction with an anode material is presented and the results discussed. The model based on a finite volume method is developed using the open software @Saturne distributed by Electricité de France. The 3D model includes the characterization of the plasma gas and of the work piece with a current continuity resolution in the whole domain. Transport and thermodynamic properties are dependent on the local temperature and on the vapours emitted by the eroded material due to the heat flux transferred by the plasma. Drag force, Marangoni force, Laplace and gravity forces are taken into account on the weld pool description. The plasma and the weld pool characteristics are presented and compared with experimental and theoretical results from the literature. For a distance between the two electrodes of d = 5 mm and an applied current intensity of I = 200 A, the vapour concentration is weak. The influence of the parameters used in the Marangoni formulation is highlighted. Finally, in agreement with some authors, we show with this global transient 3D model that it is not necessary to include the voltage drop in the energy balance.

  16. Removal of gas-phase ammonia and hydrogen sulfide using photocatalysis, nonthermal plasma, and combined plasma and photocatalysis at pilot scale.

    PubMed

    Maxime, Guillerm; Amine, Assadi Aymen; Abdelkrim, Bouzaza; Dominique, Wolbert

    2014-11-01

    This study focuses on the removal of gas-phase ammonia (NH3) and hydrogen sulfide (H2S) in a continuous reactor. Photocatalysis and surface dielectric barrier discharge (SDBD) plasma are studied separately and combined. Though the removal of volatile organic compounds by coupling plasma and photocatalysis has been reported on a number of studies in laboratory scale, this is as far as we know the first time that it is used to remove inorganic malodorous pollutants. While each separate process is able to degrade ammonia and hydrogen sulfide, a synergetic effect appears when they are combined at a pilot scale, leading to removal capacity higher than the sum of each separate process. The removal capacity is higher when the gas circulates at a higher flow rate and when pollutant concentration is higher. The presence of water vapor in the gas is detrimental to the efficiency of the process. Operating conditions also influence the production of nitrogen oxides and ozone. PMID:24996941

  17. [Experimental investigation of laser plasma soft X-ray source with gas target].

    PubMed

    Ni, Qi-liang; Gong, Yan; Lin, Jing-quan; Chen, Bo; Cao, Jian-lin

    2003-02-01

    This paper describes a debris-free laser plasma soft X-ray source with a gas target, which has high operating frequency and can produce strong soft X-ray radiation. The valve of this light source is drived by a piezoelectrical ceramic whose operating frequency is up to 400 Hz. In comparison with laser plasma soft X-ray sources using metal target, the light source is debris-free. And it has higher operating frequency than gas target soft X-ray sources whose nozzle is controlled by a solenoid valve. A channel electron multiplier (CEM) operating in analog mode is used to detect the soft X-ray generated by the laser plasma source, and the CEM's output is fed to to a charge-sensitive preamplifier for further amplification purpose. Output charges from the CEM are proportional to the amplitude of the preamplifier's output voltage. Spectra of CO2, Xe and Kr at 8-14 nm wavelength which can be used for soft X-ray projection lithography are measured. The spectrum for CO2 consists of separate spectral lines originate mainly from the transitions in Li-like and Be-like ions. The Xe spectrum originating mainly from 4d-5f, 4d-4f, 4d-6p and 4d-5p transitions in multiply charged xenon ions. The spectrum for Kr consists of separate spectral lines and continuous broad spectra originating mainly from the transitions in Cu-, Ni-, Co- and Fe-like ions. PMID:12939982

  18. Office Tubal Sterilization

    PubMed

    Zarmakoupis; Duvivier; Schulman

    1994-08-01

    We retrospectively studied 57 cases of laparoscopic bilateral tubal ligation (BTL) performed under local anesthesia at the obstetrics and gynecology outpatient center of Winthrop-University Hospital, between May 1987 and November 1992. The mean age of our patients was 34.3+10.22 years and the weight ranged between 48 to 109 kg. Contraindications included history of bleeding diathesis, severe cardiac disease, grand mal epilepsy, or unusually high anxiety level of the pt. All women were premedicated with Anaprox 500 mg po 30 minutes before the procedure. Local anesthesia was administered as follows: paracervical block; periumbilical and suprapubic injection with 1% lidocaine (10 ml); and intrauterine infusion of 4% lidocaine (5-6 ml). Insufflation of the peritoneal cavity was performed with 1 to 2 L nitrous oxide. We used a 7-mm clip applicator for the BTL. The mean operative time was 34.7 minutes. The reduction of cost compared with the same procedure performed under general anesthesia was 40%. No major complications or hospitalizations occurred. Eighty-five percent of the women expressed a high degree of satisfaction when questioned about the procedure. We conclude that office tubal sterilization under local anesthesia is safe and acceptable to both patients and physicians, offering reduced cost, elimination of general anesthesic complications, rapid recovery, and accommodation of patient preference and physician convenience. PMID:9073778

  19. Radiation sterilization of skin allograft

    NASA Astrophysics Data System (ADS)

    Kairiyama, E.; Horak, C.; Spinosa, M.; Pachado, J.; Schwint, O.

    2009-07-01

    In the treatment of burns or accidental loss of skin, cadaveric skin allografts provide an alternative to temporarily cover a wounded area. The skin bank facility is indispensable for burn care. The first human skin bank was established in Argentina in 1989; later, 3 more banks were established. A careful donor selection is carried out according to the national regulation in order to prevent transmissible diseases. As cadaveric human skin is naturally highly contaminated, a final sterilization is necessary to reach a sterility assurance level (SAL) of 10 -6. The sterilization dose for 106 batches of processed human skin was determined on the basis of the Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control (2004) and ISO 11137-2 (2006). They ranged from 17.6 to 33.4 kGy for bioburdens of >10-162.700 CFU/100 cm 2. The presence of Gram negative bacteria was checked for each produced batch. From the analysis of the experimental results, it was observed that the bioburden range was very wide and consequently the estimated sterilization doses too. If this is the case, the determination of a tissue-specific dose per production batch is necessary to achieve a specified requirement of SAL. Otherwise if the dose of 25 kGy is preselected, a standardized method for substantiation of this dose should be done to confirm the radiation sterilization process.

  20. Solidphase microextraction for the determination of the free concentration of valproic acid in human plasma by capillary gas chromatography

    Microsoft Academic Search

    Mette Krogh; Karianne Johansen; Finn Tønnesen; Knut E. Rasmussen

    1995-01-01

    The potential of solid-phase microextraction in the bioanalysis of drugs is demonstrated. The free concentration of valproic acid in human plasma was determined by equilibrium dialysis followed by solid-phase microextraction and capillary gas chromatography. Human plasma samples were dialysed at room temperature. To the dialysate was added an internal standard and the pH was adjusted to 2.5. The polymethylsiloxane-coated fused-silica

  1. Solvent-modified solid-phase microextraction for the determination of diazepam in human plasma samples by capillary gas chromatography

    Microsoft Academic Search

    Mette Krogh; Hege Grefslie; Knut E. Rasmussen

    1997-01-01

    This paper describes microextraction and gas chromatographic analysis of diazepam from human plasma. The method was based on immobilisation of 1.5 ?l of 1-octanol on a polyacrylate-coated fiber designed for solid-phase microextraction. The solvent-modified fibre was used to extract diazepam from the samples. The plasma sample was pre-treated to release diazepam from the protein binding. The fibre was inserted into

  2. Pyrolysis\\/gasification of biomass for synthetic fuel production using a hybrid gas–water stabilized plasma torch

    Microsoft Academic Search

    G. Van Oost; M. Hrabovsky; V. Kopecky; M. Konrad; M. Hlina; T. Kavka

    2008-01-01

    An experimental plasma-chemical reactor equipped with a novel hybrid gas–water stabilized torch is available at IPP Prague for the innovative and environmentally friendly plasma treatment of waste streams with a view to their sustainable energetic and chemical valorization and to a reduction of the emission of greenhouse gases. Gasification\\/pyrolysis of biomass was experimentally studied using crushed wood as a model

  3. Silicon oxynitride gas barrier coatings on poly(ether sulfone) by plasma-enhanced chemical vapor deposition

    Microsoft Academic Search

    Juno Shim; Ho Gyu Yoon; Sang-Hyun Na; Insun Kim; Soonjong Kwak

    2008-01-01

    Thin silicon oxynitride (SiOxNy) has been deposited for a gas barrier layer on the surface of poly(ether sulfone) film using plasma-enhanced chemical vapor deposition (PECVD) of a mixture of hexamethyldisiloxane (HMDSO) and ammonia. The chemical structure of the deposited layer varied from organic to inorganic structures depending on RF plasma input power applied to the reaction system. A silicon-based undercoat

  4. Sensitive and selective gas chromatographic methods for the quantitation of camphor, menthol and methyl salicylate from human plasma

    Microsoft Academic Search

    Jennifer S Valdez; Debra K Martin; Michael Mayersohn

    1999-01-01

    Analytical methods using gas chromatography–flame ionization detection (GC–FID) for the quantitation of camphor and menthol and GC–MS for the quantitation of methyl salicylate have been developed for measurement of low concentrations from human plasma. Anethole serves as the internal standard for camphor and menthol and ethyl salicylate serves as the internal standard for methyl salicylate. Plasma samples undergo multiple, sequential

  5. Microbial Inactivation in the Liquid Phase Induced by Multigas Plasma Jet

    PubMed Central

    Takamatsu, Toshihiro; Uehara, Kodai; Sasaki, Yota; Hidekazu, Miyahara; Matsumura, Yuriko; Iwasawa, Atsuo; Ito, Norihiko; Kohno, Masahiro; Azuma, Takeshi; Okino, Akitoshi

    2015-01-01

    Various gas atmospheric nonthermal plasmas were generated using a multigas plasma jet to treat microbial suspensions. Results indicated that carbon dioxide and nitrogen plasma had high sterilization effects. Carbon dioxide plasma, which generated the greatest amount of singlet oxygen than other gas plasmas, killed general bacteria and some fungi. On the other hand, nitrogen plasma, which generated the largest amount of OH radical, killed ?6 log of 11 species of microorganisms, including general bacteria, fungi, acid-fast bacteria, spores, and viruses in 1–15 min. To identify reactive species responsible for bacterial inactivation, antioxidants were added to bacterial suspensions, which revealed that singlet oxygen and OH radicals had greatest inactivation effects. PMID:26173107

  6. Microbial Inactivation in the Liquid Phase Induced by Multigas Plasma Jet.

    PubMed

    Takamatsu, Toshihiro; Uehara, Kodai; Sasaki, Yota; Hidekazu, Miyahara; Matsumura, Yuriko; Iwasawa, Atsuo; Ito, Norihiko; Kohno, Masahiro; Azuma, Takeshi; Okino, Akitoshi

    2015-01-01

    Various gas atmospheric nonthermal plasmas were generated using a multigas plasma jet to treat microbial suspensions. Results indicated that carbon dioxide and nitrogen plasma had high sterilization effects. Carbon dioxide plasma, which generated the greatest amount of singlet oxygen than other gas plasmas, killed general bacteria and some fungi. On the other hand, nitrogen plasma, which generated the largest amount of OH radical, killed ?6 log of 11 species of microorganisms, including general bacteria, fungi, acid-fast bacteria, spores, and viruses in 1-15 min. To identify reactive species responsible for bacterial inactivation, antioxidants were added to bacterial suspensions, which revealed that singlet oxygen and OH radicals had greatest inactivation effects. PMID:26173107

  7. 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.

  8. Investigation of parameters and uninterrupted service of a generator of gas-discharge plasma based on a nonsustained hot-cathode arc discharge in gas

    NASA Astrophysics Data System (ADS)

    Borisov, D. P.; Korotaev, A. D.; Kuznetsov, V. M.; Chulkov, E. V.

    2014-11-01

    The design of an electrode system and the characteristics of a gas-discharge plasma source (generator) based on an arc discharge in gas sustained by thermionic emission are presented. The results of an experimental investigation of the service life of a thermionic (hot) cathode of the plasma generator are reported as a function of the discharge current and voltage and the cathode filament power. It is shown that an increase in the burning voltage from 28 to 60 V considerably reduces the service life of the hot cathode, while the discharge current and the cathode filament power exert a less critical effect on its lifetime. The conditions necessary for achieving long-term service life parameters and high efficiency of plasma generation are found out.

  9. Determination of phosphoric acid triesters in human plasma using solid-phase microextraction and gas chromatography coupled to inductively coupled plasma mass spectrometry.

    PubMed

    Shah, Monika; Meija, Juris; Cabovska, Baiba; Caruso, Joseph A

    2006-01-27

    A simple and sensitive method for determination of phosphoric acid triesters at trace levels in human plasma sample is described. In this work, solid-phase microextraction (SPME) is employed as a sample preparation procedure for extraction and pre-concentration of alkyl and aryl phosphates followed by gas chromatography coupled to inductively coupled plasma mass spectrometry (GC-ICP-MS) for phosphorus-specific and very sensitive determination of these compounds in human plasma. The detection limits from blood plasma were 50 ngL(-1) (tripropyl phosphate), 17 ngL(-1) (tributyl phosphate), 240 ngL(-1) (tris(2-chloroethyl) phosphate) and 24 ngL(-1) (triphenyl phosphate). Sample preparation involves plasma deproteinization followed by direct immersion SPME with 65 microm poly(dimethylsiloxane/divinylbenzene) fiber. Extraction was performed at 40 degrees C for 30 min and at pH 7.0 in 10 mM sodium carbonate buffer. The reported method, to our knowledge, describes the first application of SPME with element-specific detection for analysis of phosphoric acid esters. Application of the method to the plasma samples, previously stored in poly(vinyl chloride) plasma bags revealed the presence of triphenyl phosphate, which was further confirmed by SPME GC time-of-flight high-resolution mass spectrometry. PMID:16337211

  10. Minimum Condition of Target Gas Material at an Ionization-Stage Control Scheme in a Laser-Plasma Electron Acceleration

    NASA Astrophysics Data System (ADS)

    Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Kiriyama, Hiromitsu; Okada, Hajime; Pirozhkov, Alexander S.; Bulanov, Sergei V.; Kondo, Kiminori; Bolton, Paul R.

    We report on minimum condition of target gas material at an ionization-stage control scheme in a laser-plasma electron acceleration. In order to study on such dependence, feature of energetic electron beam generation in argon and neon were compared. The energetic electron generations were significantly different between two gas targets. Propagations of driving laser were also different. Results of ray-tracing suggest that such dependencies were caused by the diffraction of laser beam by a gradient of electron plasma density created by the ionization stage slopes.

  11. Peculiarities of the beam-plasma discharge development in high-pressure gas and prospects of its application

    SciTech Connect

    Berezina, G. P., E-mail: Berezina@kipt.kharkov.ua; Us, V. S. [National Science Center Kharkov Institute of Physics and Technology (Ukraine)

    2011-12-15

    The dynamics of a stationary beam-plasma discharge at the neutral gas pressure of 10{sup -3}-1 Torr is investigated. Three discharge modes have been revealed: two of them are characterized by novel properties and have not been studied as of yet. Dissipative instabilities with different increments have been found. The generation of ion flows has been studied and the experiments on 'dry' cleaning of the metal specimen surfaces using them have been carried out. The pressure ranges in a neutral gas at which the discharge can be efficiently applied in nonequilibrium plasma chemistry are given.

  12. Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

    NASA Astrophysics Data System (ADS)

    Frolov, V.; Ivanov, D.; Toropchin, A.

    2014-11-01

    Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying.

  13. Kinetics of gas-phase chemical reactions in a remote RF plasma reactor with electron spin resonance

    SciTech Connect

    Janca, J.; Talsky, A.; Zvonicek, V. [Masaryk Univ., Brno (Czech Republic)

    1995-12-31

    A remote RF plasma reactor is inherently a reactive gas flow system in which the gas-phase chemical reactions of interest occur outside (downstream) the plasma and involve paramagnetic ground state or excited species (e.g. H, O, O{sub 2}, N, NO). Consequently, the kinetics of the gas-phase reactions can be quantitatively characterized by electron spin resonance (ESR). Gas flows and tube pressure are essential parameters for quantitative analysis. The ESR measurements provides the absolute value of paramagnetic species, the determination of recombination and rate coefficients of selected reactions. The goal of the measurements described in the present paper was to find the wall recombination coefficient in pure nitrogen and oxygen and to explain the effect of impurities on both dissociation and recombination of N and O. Next the reaction of atomic oxygen with the molecules of tetraethoxysilane (TEOS) was studied and the kinetic coefficient of this reaction was determined.

  14. A neutral strongly coupled laser-produced plasma by strong-field ionization in a gas jet

    NASA Astrophysics Data System (ADS)

    Bergeson, S. D.; Lyon, M.; Peatross, J. B.; Harrison, N.; Crunkleton, D.; Wilson, J.; Rupper, S.; Diaw, A.; Murillo, M. S.

    2015-06-01

    We report measurements of a neutral strongly coupled plasma generated by focusing a femtosecond-duration laser pulse into a room-temperature gas jet. The ion temperature in this plasma is determined by the plasma density through the disorder-induced heating effect. We present measurements of the mass, radius, and energy dependence of the time-varying ion density as the plasma expands. Molecular dynamics model indicate that higher values of the strong coupling parameter could be achieved if the plasma is ionized again by a second laser pulse that follows the first one. However, the final value of the coupling parameter appears to be only weakly dependent on the final ionization state.

  15. Solidphase microextraction–capillary gas chromatography combined with microwave-induced plasma atomic-emission spectrometry for selenite determination

    Microsoft Academic Search

    Emmanouil Dimitrakakis; Christina Haberhauer-Troyer; Yo Abe; Maria Ochsenkühn-Petropoulou; Erwin Rosenberg

    2004-01-01

    The use of solid-phase microextraction (SPME) with gas chromatography coupled to microwave-induced plasma atomic-emission detection (GC–MIP-AED) is described for selenite [Se(IV)] speciation. Aqueous standards were derivatised with sodium tetraethyl- or tetrapropylborate and extracted by SPME. Headspace extraction of the ethyl and propyl derivatives was studied. Relevant experimental conditions were optimised, including conditions for derivatisation and extraction and those of gas

  16. Genomic networks of hybrid sterility.

    PubMed

    Turner, Leslie M; White, Michael A; Tautz, Diethard; Payseur, Bret A

    2014-02-01

    Hybrid dysfunction, a common feature of reproductive barriers between species, is often caused by negative epistasis between loci ("Dobzhansky-Muller incompatibilities"). The nature and complexity of hybrid incompatibilities remain poorly understood because identifying interacting loci that affect complex phenotypes is difficult. With subspecies in the early stages of speciation, an array of genetic tools, and detailed knowledge of reproductive biology, house mice (Mus musculus) provide a model system for dissecting hybrid incompatibilities. Male hybrids between M. musculus subspecies often show reduced fertility. Previous studies identified loci and several X chromosome-autosome interactions that contribute to sterility. To characterize the genetic basis of hybrid sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven 'hotspots,' seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL-but not cis eQTL-were substantially lower when mapping was restricted to a 'fertile' subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. The integrated mapping approach we employed is applicable in a broad range of organisms and we advocate for widespread adoption of a network-centered approach in speciation genetics. PMID:24586194

  17. Sterilant gas disinfection of fruits and vegetables

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous foodborne outbreaks have been associated with the consumption of fresh fruits and vegetables. Commercial aqueous wash treatments for fresh produce are limited in their ability to inactivate and/or remove human pathogen contaminants. Gases can penetrate into crevices and niches on produce wh...

  18. 21 CFR 522.82 - Aminopropazine fumarate sterile solution injection.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...false Aminopropazine fumarate sterile solution injection. 522.82 Section 522...82 Aminopropazine fumarate sterile solution injection. (a) Specifications...aminopropazine fumarate sterile aqueous solution, veterinary, contains...

  19. 21 CFR 522.82 - Aminopropazine fumarate sterile solution injection.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Aminopropazine fumarate sterile solution injection. 522.82 Section 522...82 Aminopropazine fumarate sterile solution injection. (a) Specifications...aminopropazine fumarate sterile aqueous solution, veterinary, contains...

  20. Characterization of silicon oxide gas barrier films with controlling to the ion current density (ion flux) by plasma enhanced chemical vapor deposition

    Microsoft Academic Search

    Su B. Jin; Youn J. Kim; Yoon S. Choi; In S. Choi; Jeon G. Han

    2010-01-01

    Silicon oxide gas barrier films were deposited on polyethylene terephthalate (PET) substrates by plasma enhanced chemical vapor deposition (PE-CVD) for applications to transparent barrier packaging. The barrier properties of the silicon oxide coated film were optimized by varying the bias conditions and input power in the radio frequency plasma. The plasma diagnostics, ion current density and substrate temperature were characterized

  1. Development of a plasma sprayed ceramic gas path seal for high pressure turbine applications

    NASA Technical Reports Server (NTRS)

    Shiembob, L. T.; Hyland, J. F.

    1979-01-01

    Development of the plasma sprayed graded, layered ZrO2/CoCrAlY seal system for gas turbine engine blade tip seal application up to 1589 K (2400 F) surface temperature was continued. Methods of improvement of the cyclic thermal shock resistance of the sprayed zirconia seal system were investigated. The most promising method, reduction of the ceramic thickness and metallic substrate stiffness were selected based upon potential and feasibility. Specimens were fabricated and experimentally evaluated to: (1) substantiate the capacity of the geometry changes to reduce operating stresses in the sprayed structure; and (2) define the abradability, erosion, thermal shock and physical property characteristic for the sprayed ceramic seal system. Thermal stress analysis was performed and correlated with thermal shock test results.

  2. Gas-to-Particle Conversion in Surface Discharge Nonthermal Plasmas and Its Implications for Atmospheric Chemistry

    PubMed Central

    Kim, Hyun-Ha; Ogata, Atsushi

    2011-01-01

    This paper presents some experimental data on gas-to-particle conversion of benzene using nonthermal plasma (NTP) technology and discusses the possibility of its technical application in atmospheric chemistry. Aerosol measurement using a differential mobility analyzer (DMA) revealed that the parts of benzene molecules were converted into a nanometer-sized aerosol. Aerosol formation was found to be highly related with the missing part in carbon balance. Scanning electron microscopy analysis showed that the aerosols formed in synthetic humid air are the collection of nanoparticles. The carbonyl band (C=O) was found to be an important chemical constituent in the aerosol. The potential of the NTP as an accelerated test tool in studying secondary organic aerosol (SOA) formation from VOCs will be also addressed. PMID:22163781

  3. Numerical Simulation of Membrane Reactor for Detritiation of Plasma Exhaust Gas

    SciTech Connect

    Munakata, K. [Kyushu University (Japan); Bornschein, B. [Forschungszentrum Karlsruhe (Germany); Corneli, D. [Forschungszentrum Karlsruhe (Germany); Glugla, M. [Forschungszentrum Karlsruhe (Germany)

    2005-07-15

    One of the design targets for the ITER Tokamak Exhaust Processing system is to suppress the loss of tritium to less than 10{sup -5} g/h into the Normal Vent Detritiation System of the Tritium Plant. The plasma exhaust gas, therefore, needs to be processed with an overall tritium removal efficiency of about 10{sup 8}. Such a high decontamination factor can be achieved by multistage processes. The third step of the three step CAPER process developed at the TLK is based on a so-called permeator catalyst (PERMCAT) reactor, a direct combination of a Pd/Ag permeation membrane and a catalyst bed. In this work, a numerical simulation of the PERMCAT reactor was performed and the result was compared with experimental data.

  4. Magnetic Ignition of Pulsed Gas Discharges in Air of Low Pressure in a Coaxial Plasma Gun

    NASA Technical Reports Server (NTRS)

    Thom, Karlheinz; Norwood, Joseph, Jr.

    1961-01-01

    The effect of an axial magnetic field on the breakdown voltage of a coaxial system of electrodes has been investigated by earlier workers. For low values of gas pressure times electrode spacing, the breakdown voltage is decreased by the application of the magnetic field. The electron cyclotron radius now assumes the role held by the mean free path in nonmagnetic discharges and the breakdown voltage becomes a function of the magnetic flux density. In this paper the dependence of the formative time lag as a function of the magnetic flux density is established and the feasibility of using a magnetic field for igniting high-voltage, high-current discharges is shown through theory and experiment. With a 36 microfarad capacitor bank charged to 48,000 volts, a peak current of 1.3 x 10( exp 6) amperes in a coaxial type of plasma gun was achieved with a current rise time of only 2 microseconds.

  5. Plasma-assisted reduction of carbon dioxide in the gas phase

    SciTech Connect

    Maya, L. [Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2000-01-01

    The reduction of carbon dioxide by hydrogen, which constitutes the reverse water-gas shift reaction, is an active area of research because of its connection with the production of methanol and other fuels. Representative references are given, that have been reported in the catalysis literature where most of this research is described. In contrast with this, studies dealing with the plasma-assisted reduction of carbon dioxide, as a subset of the subject, are rather limited. A variety of products such as diamond, oxalic acid or fuel species have been obtained depending on the conditions. The present study was undertaken to explore the possibility of obtaining formic acid through the plasma-assisted reduction of carbon dioxide given the precedent that even a more complex molecule such as oxalic has been obtained. The production of formic acid was not anticipated to take place cleanly given the mechanistic complexity of such a process. The study was conducted nevertheless to seek an alternative to an electrochemical pathway to reduce carbon dioxide that has obvious shortcomings because of the requirement to dissolve the gas in a solvent, in addition to the limited concentration of reactant and products that might be obtained. Formic acid in the form of formate is a component of a cycle conceived to trap tritium from contaminated ground water that uses carbon dioxide from a selective oxidation step and hydrogen/tritium from the electrochemical reduction of the contaminated water. The electrochemical oxidation of formate is catalyzed by means of terpyridine bipyridine oxo ruthenium (IV), a complex that shows remarkable isotope effects so that tritiated formate is selectively enriched and may be separated by ion exchange. (c) 2000 American Vacuum Society.

  6. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    SciTech Connect

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  7. Cytoplasmic Sterility Factors in VICIA FABA L

    PubMed Central

    Edwardson, J. R.; Bond, D. A.; Christie, R. G.

    1976-01-01

    Tissues of cytoplasmic male sterile, maintainer, restorer, and restored lines, and sterile plants which reverted to fertility in Vicia faba were examined in ultrathin sections. Cytoplasmic spherical bodies (CSB), ca. 70 nm in diameter, were observed in tissues of all sterile plants but not in tissues of maintainer, restorer or restored sterile plants. No CSB were observed in a reverted fertile branch of a tiller-sterile plant, nor in 5 of 6 reverted fertile plants. One reverted fertile plant contained CSB in ovules. It is proposed that the CSB are the sites of, or possibly, products of, sterility factors in Vicia faba. PMID:17248701

  8. Generation of dense multicharged ion flows from an ECR plasma confined in a quasi-gas-dynamic magnetic cusp trap

    SciTech Connect

    Bokhanov, A. F.; Zorin, V. G.; Izotov, I. V.; Razin, S. V.; Sidorov, A. V.; Skalyga, V. A. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2007-05-15

    The possibility of generating dense multicharged ion beams with a current density as high as {approx}1 A/cm{sup 2} from an ECR plasma confined in a quasi-gas-dynamic cusp trap is studied both theoretically and experimentally. The most important advantages of this type of ion source are that the plasma in the cusp is stabile against MHD perturbations and that a trap intended to operate at fairly high pump-field frequencies (above 30 GHz) is relatively inexpensive. A theoretical model of confinement of a high-density nonequilibrium ECR plasma (T{sub e} >> T{sub i}) in an open magnetic trap is proposed and results are presented from model experiments with an {approx}30-cm-long cusp trap (here, by the cusp length is meant the volume of a paraxial magnetic tube divided by the area of its cross sections in magnetic mirrors) pumped by a pulsed microwave field with a frequency of 37.5 GHz and power of 100 kW. The possibility of achieving a quasi-gas-dynamic regime of plasma confinement of an ECR plasma in a cusp trap is demonstrated. Ion beams with a average ion charge number of 2-4 (depending on the sort of working gas) and current densities unprecedented for ECR sources are obtained. Good agreement between theoretical and experimental results makes it possible to reliably predict the ion beam parameters that can be achieved at even higher microwave frequencies.

  9. Self-consistent simulation of N_2/H2 gas plasma for low-k material etching

    NASA Astrophysics Data System (ADS)

    Shon, Chae-Hwa; Makabe, Toshiaki

    2003-10-01

    We have developed a self-consistent modeling tool for H_2/N2 gas in two-frequency capacitively coupled plasma (2f-CCP) [1], based on the relaxation continuum (RCT) model [2]. As the resistance-capacitance (RC) delay of signals through interconnection materials becomes important, low-k materials have been proposed to solve the probelm. H_2/N2 gas is a promising candidate for the etching of future low-k dielectric materials because of high selectivity and environmentally friendly process. There are many reactions among the vibrationally excited states, electronically excited states, and ionized plasma in the N_2/H2 gas, that have to be considered self-consistently. In this model, plasma and neutrals are calculated self-consistently by iterating the simulation of both species till a spatiotemporal periodic steady state profile could be obtained. The spatiotemporal profiles and reactions of plasma and neutrals are discussed as a simulation results of the model. [1] C. H. Shon and T. Makabe, Submitted to Phys. Rev. E. [2] T. Makabe, "Advences in Low Temperature RF plasmas" (Elsevier, 2002).

  10. Interferometric investigation of the influence of argon buffer gas on the characteristics of laser-induced aluminum plasmas.

    PubMed

    Oh, Seong Y; Singh, Jagdish P; Lim, Changhwan

    2014-06-10

    An interferometric analysis was performed to investigate the influence of argon (Ar) buffer gas on the characteristics of laser-induced aluminum (Al) plasma at atmospheric pressure. The plasma was produced by focusing a Q-switched Nd:YAG laser pulse (?=1064??nm, pulse duration ?5??ns, E=6.0??mJ) onto an Al target. The interference patterns were constructed using a Nomarski interferometer incorporated with a frequency-doubled, Q-switched Nd:YAG laser (?=532??nm, pulse duration ?10??ns) that generates an interferometric probe beam. The interferometric measurements were carried out as a function of the elapsed time after the onset of breakdown under the conditions of open air and an Ar gas jet flow (5??l/min). With the injection of an Ar buffer gas jet in the ablation process, an increase in electron density and a preferential axial plasma expansion of the plasma plume were observed during the early stages of plasma formation as a consequence of increased inverse-Bremsstrahlung (IB) absorption efficiency. PMID:24921120

  11. Source gas depletion in narrow metal tube during internal DLC coating with microwave-excited high-density near plasma

    NASA Astrophysics Data System (ADS)

    Matsui, Ryosuke; Kosaka, Hiroyuki; Umehara, Noritsugu

    2012-10-01

    In internal DLC (Diamond-Like Carbon) coating to mm-sized narrow metal tubes by using MVP (Microwave-sheath Voltage combination Plasma) method, axially uniform distribution of film thickness can be obtained by repeating the depletion and homogenization of source gas in a coated tube during plasma-on time Ton and plasma-off time Toff of pulsed plasma generation, respectively. DLC was deposited to the inner surface of a stainless-steel tube 4.4 mm in inner diameter and 50 mm in length with small holes of ?=0.4 mm fabricated at every 10 mm, where the flow rates of Ar and methane were controlled to be 14 and 2 sccm, respectively, at a total gas pressure of 80 Pa. A pulsed negative voltage of --200 V was applied to the tube at a pulse frequency of 10 Hz and duty ratio of 3.2%, synchronizing a pulsed injection of 2.45-GHz microwaves at the same pulse frequency (Ton=3.2 ms and Toff=96.8 ms). The high-speed camera image showed that the emission (696, 706 nm) from Ar atom was approximately constant during plasma-on time. On the other hand, the emission (468-474 nm) from C2 dimer was decreased until Ton =1.5 ms, and then converged in a constant value; this is ascribed to the consumption of CH4 gas which is considered to be a main source of C2 dimer formation.

  12. Plasma density measurement in a gas-filled X-band backward wave oscillator with a double conversion heterodyne microwave interferometer

    Microsoft Academic Search

    Xiaoling Zhai; Eusebio Garate; Robert Prohaska; Gregory Benford

    1996-01-01

    Plasma density was measured with a heterodyne microwave interferometer in both a gas-filled X-band backward wave oscillator (BWO) and in a smooth tube. Plasma is generated by impact ionization of a 650 kV, 2 kA electron beam. For fixed gas pressure we found that the plasma density rise in the operating BWO was much faster than in a smooth tube,

  13. Quantification of busulfan in plasma by gas chromatography-mass spectrometry following derivatization with tetrafluorothiophenol.

    PubMed

    Quernin, M H; Poonkuzhali, B; Montes, C; Krishnamoorthy, R; Dennison, D; Srivastava, A; Vilmer, E; Chandy, M; Jacqz-Aigrain, E

    1998-05-01

    A specific and highly sensitive method has been developed for the determination of busulfan in plasma by gas chromatography-mass spectrometry using a deuterium-labeled busulfan (busulfan-d8) as internal standard. Plasma containing busulfan and busulfan-d8 were extracted with ethyl acetate and derivatized with 2,3,5,6-tetrafluorothiophenol prior to the monitoring of specific ions. The limit of quantification of the assay was 20 ng/ml and the calibration curve was linear over the range of 10 to 2000 ng/ml of derivatized busulfan. This method was in good agreement with the GC-MS assay using derivatization with sodium iodide and measuring diiodobutane. In addition, a pharmacokinetic study of busulfan was conducted in six children. The apparent oral clearance was 5.7+/-1.9 ml/kg/min and the volume of distribution was 1.0+/-0.4 l/kg and were similar to those previously reported in pediatric patients. PMID:9653925

  14. Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography-mass spectrometry.

    PubMed

    Batista, Catarina; Berisha, Myftar; Karst, Matthias; Salim, Kahlid; Schneider, Udo; Brenneisen, Rudolf

    2005-06-01

    A method using gas chromatography-mass spectrometry (GC-MS) and solid-phase extraction (SPE) was developed for the determination of ajulemic acid (AJA), a non-psychoactive synthetic cannabinoid with interesting therapeutic potential, in human plasma. When using two calibration graphs, the assay linearity ranged from 10 to 750 ng/ml, and 750 to 3000 ng/ml AJA. The intra- and inter-day precision (R.S.D., %), assessed across the linear ranges of the assay, was between 1.5 and 7.0, and 3.6 and 7.9, respectively. The limit of quantitation (LOQ) was 10 ng/ml. The amount of AJA glucuronide was determined by calculating the difference in the AJA concentration before ("free AJA") and after enzymatic hydrolysis ("total AJA"). The present method was used within a clinical study on 21 patients suffering from neuropathic pain with hyperalgesia and allodynia. For example, plasma levels of 599.4+/-37.2 ng/ml (mean+/-R.S.D., n=9) AJA were obtained for samples taken 2 h after the administration of an oral dose of 20 mg AJA. The mean AJA glucuronide concentration at 2h was 63.8+/-127.9 ng/ml. PMID:15866495

  15. 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

  16. Adhesive forces and surface properties of cold gas plasma treated UHMWPE.

    PubMed

    Preedy, Emily Callard; Brousseau, Emmanuel; Evans, Sam L; Perni, Stefano; Prokopovich, Polina

    2014-10-20

    Cold atmospheric plasma (CAP) treatment was used on ultra-high molecular weight polyethylene (UHMWPE), a common articulating counter material employed in hip and knee replacements. UHMWPE is a biocompatible polymer with low friction coefficient, yet does not have robust wear characteristics. CAP effectively cross-links the polymer chains of the UHMWPE improving wear performance (Perni et al., Acta Biomater. 8(3) (2012) 1357). In this work, interactions between CAP treated UHMWPE and spherical borosilicate sphere (representing model material for bone) were considered employing AFM technique. Adhesive forces increased, in the presence of PBS, after treatment with helium and helium/oxygen cold gas plasmas. Furthermore, a more hydrophilic surface of UHMWPE was observed after both treatments, determined through a reduction of up to a third in the contact angles of water. On the other hand, the asperity density also decreased by half, yet the asperity height had a three-fold decrease. This work shows that CAP treatment can be a very effective technique at enhancing the adhesion between bone and UHMWPE implant material as aided by the increased adhesion forces. Moreover, the hydrophilicity of the CAP treated UHMWPE can lead to proteins and cells adhesion to the surface of the implant stimulating osseointegration process. PMID:25431523

  17. Investigation of helium addition for laser-induced plasma spectroscopy of pure gas phase systems: Analyte interactions and signal enhancement

    E-print Network

    Hahn, David W.

    of the data, it is concluded that the role of metastable helium is not as important as the overall changesInvestigation of helium addition for laser-induced plasma spectroscopy of pure gas phase systems; accepted 2 October 2007 Available online 9 October 2007 Abstract The role of helium addition on the analyte

  18. Discharge in the gas channel with liquid walls as generator of non-thermal plasma at atmospheric pressure

    Microsoft Academic Search

    I. Prysiazhnevych; V. Yukhymenko; V. Chernyak; S. Olshevskiy; V. Naumov; J. Skalny; S. Matejcik; M. Verovchuk; S. Sidoruk

    Optical diagnostics of the discharge in the gas channel with liquid walls at atmospheric pressure was made. Boltzmann population distributions of the excited electronic states of hydrogen, oxygen, copper atoms and vibronic C 3 ? states of nitrogen molecules in the generated plasma were shown. Corresponding electronic (Te) and vibration (Tv) temperatures were determined from Boltzmann plot and non-isothermal character

  19. The respective roles of UV photons and oxygen atoms in plasma sterilization at reduced gas pressure: the case of N2-O2 mixtures

    Microsoft Academic Search

    Nicolas Philip; Bachir Saoudi; Marie-Charlotte Crevier; Michel Moisan; Jean Barbeau; Jacques Pelletier

    2002-01-01

    In the reduced-pressure (?10 torr) afterglow stemming from discharges in O2- containing mixtures such as N2-O2, the test-reference spores are ultimately inactivated by UV photons through destruction of their genetic material (DNA). To show this, we assume the inactivation to result from a sufficiently large number of successful hits of the DNA strands by UV photons. This implies that the

  20. Cytotoxicity and thermomechanical behavior of biomedical shape-memory polymer networks post-sterilization

    Microsoft Academic Search

    C. M. Yakacki; M. B. Lyons; B. Rech; K. Gall; R. Shandas

    2008-01-01

    Shape-memory polymers (SMPs) are being increasingly proposed for use in biomedical devices. This paper investigates the cytotoxicity, surface characteristics and thermomechanics of two acrylate-based SMP networks as a function of sterilization using a minimal essential media elution test, FTIR-ATR and dynamic mechanical analysis (DMA). Networks sterilized by low-temperature plasma elicited a cytotoxic response and are shown to completely destroy the

  1. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-10-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment.

  2. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet.

    PubMed

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T H; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  3. What AGN revergeration maps tell us: plasma simulations of dense accreting gas

    NASA Astrophysics Data System (ADS)

    Ferland, Gary

    2014-10-01

    The Cycle 21 large program, "Mapping the AGN Broad-line region by reverberation", will produce the definitive line-continuum reverberation dataset. These HST observations should "clarify the nature of the broad-line region, its role in the apparently complicated accretion/outflow process, and determine definitively the veracity and accuracy of the AGN reverberation-based black hole masses". This proposal aims to improve Cloudy simulations of the dense gas emitting the spectrum so that photoionization theory can meet the challenge posed by these new observations. Two specific advances, implementing physical processes now expected to be important, are proposed. The first involves electron scattering enhancement of H I lines. The lines will be broadened and enhanced by scattering off warm {8 000 K} electrons in the extended neutral gas deep within the cloud or disk, affecting both the line profile and intensity. The second involves collisional suppression of dielectronic recombination, the dominant process responsible for recombination of heavy-element UV lines such as C IV 1549, C III] 1909, Mg II 2798, etc. This is made possible by access to a large body of atomic rates within OpenADAS, and will impact predictions of essentially the entire Broad-line region spectrum. Both advances will become part of Cloudy, a publically available and widely used plasma simulation code.

  4. Surface modifications by gas plasma control osteogenic differentiation of MC3T3-E1 cells.

    PubMed

    Barradas, Ana M C; Lachmann, Kristina; Hlawacek, Gregor; Frielink, Cathelijne; Truckenmoller, Roman; Boerman, Otto C; van Gastel, Raoul; Garritsen, Henk; Thomas, Michael; Moroni, Lorenzo; van Blitterswijk, Clemens; de Boer, Jan

    2012-08-01

    Numerous studies have shown that the physicochemical properties of biomaterials can control cell activity. Cell adhesion, proliferation, differentiation as well as tissue formation in vivo can be tuned by properties such as the porosity, surface micro- and nanoscale topography and chemical composition of biomaterials. This concept is very appealing for tissue engineering since instructive properties in bioactive materials can be more economical and time efficient than traditional strategies of cell pre-differentiation in vitro prior to implantation. The biomaterial surface, which is easy to modify due to its accessibility, may provide the necessary signals to elicit a certain cellular behavior. Here, we used gas plasma technology at atmospheric pressure to modify the physicochemical properties of polylactic acid and analyzed how this influenced pre-osteoblast proliferation and differentiation. Tetramethylsilane and 3-aminopropyl-trimethoxysilane with helium as a carrier gas or a mixture of nitrogen and hydrogen were discharged to polylactic acid discs to create different surface chemical compositions, hydrophobicity and microscale topographies. Such modifications influenced protein adsorption and pre-osteoblast cell adhesion, proliferation and osteogenic differentiation. Furthermore polylactic acid treated with tetramethylsilane enhanced osteogenic differentiation compared to the other surfaces. This promising surface modification could be further explored for potential development of bone graft substitutes. PMID:22522130

  5. Plasma-chemical treatment of hydrogen sulfide in natural gas processing. Final report, May 1991--December 1992

    SciTech Connect

    Harkness, J.B.L.; Doctor, R.D. [Argonne National Lab., IL (United States)

    1993-05-01

    A new process for the treatment of hydrogen sulfide waste that uses microwave plasma-chemical technology has been under development in Russia and the United States. Whereas the present waste-treatment technology, at best, only recovers sulfur, this novel process recovers both hydrogen and sulfur by dissociating hydrogen sulfide in a plasma by means of a microwave or radio-frequency reactor. A research project has been undertaken to determine the suitability of the plasma process in natural gas processing applications. The experiments tested acid-gas compositions with 30--65% carbon dioxide, 0--7% water, and 0--0.2% of a standard mixture of pipeline gas. The balance gas in all cases was hydrogen sulfide. The reactor pressure for the experiments was 50 torr, and the microwave power was 1.0 kW. Conversions of hydrogen sulfide ranged from 80 to 100%, while 35--50% of the carbon dioxide was converted to carbon monoxide. This conversion of carbon dioxide resulted in a loss of hydrogen production and an energy loss from a hydrogen sulfide waste-treatment perspective. Tests of a direct natural gas treatment concept showed that hydrocarbon losses were unacceptably high; consequently, the concept would not be economically viable.

  6. Novel improvements in perioperative sterility.

    PubMed

    Prabhakar, Amit; Wyche, Melville Q; Ehrhardt, Ken P; Ma, John G; Elhassan, Amir O; Urman, Richard D; Kave, Alan David

    2015-01-01

    Operative sterility is a critical factor with regard to infection in the postoperative period. In recent years, techniques and devices have been developed to reduce the potential for exposure to pathogens. This brief review details the SteriCup, a unique product that has the potential to reduce the risk of healthcare-acquired infections. The SteriCup provides a designated sterile area to store suction catheters and removed endotracheal tubes and allows for their simple and safe disposal. Devices such as the SteriCup have the potential to improve operating room systems and minimize potential for operative infection. PMID:26062318

  7. Effect of shielding gas plasma on monitoring signals in laser welding: Features of monitoring methods for laser welding and their application (1)

    Microsoft Academic Search

    M. Watanabe; T. Nakabayasi; H. Hiraga; T. Inoue; A. Matsunawa

    1999-01-01

    The shielding gas used in laser welding plays an important role in obtaining high-quality welds. Argon shielding gas, being cheap to use, has most notably entered widespread use, but it faces the growing problem of plasma generation in higher-power laser welding.This series of papers describes investigations of the generation conditions of shielding gas plasma and its behaviour, the correlation between

  8. Dusty plasmas

    Microsoft Academic Search

    Vladimir E Fortov; Aleksei G Khrapak; Sergei A Khrapak; Vladimir I Molotkov; Oleg F Petrov

    2004-01-01

    The properties of dusty plasmas — low-temperature plasmas containing charged macroparticles — are considered. The most important elementary processes in dusty plasmas and the forces acting on dust particles are investigated. The results of experimental and theoretical investigations of different states of strongly nonideal dusty plasmas — crystal-like, liquid-like, gas-like — are summarized. Waves and oscillations in dusty plasmas, as

  9. The impact of plasma-wall interaction on the gas mixing efficiency in electron cyclotron resonance ion source

    SciTech Connect

    Schachter, L.; Dobrescu, S. [National Institute for Physics and Nuclear Engineering, Bucharest (Romania); Stiebing, K. E. [Institut fuer Kernphysik der J. W. Goethe-Universitaet, Frankfurt/Main (Germany)

    2012-02-15

    It is generally accepted that different effects are necessary to explain the gas mixing method of increasing the output of highly charged ions from an ECRIS. The two most important effects are the mass effect and the dilution effect. Their relative weights have not been determined experimentally yet, but it is generally assumed that the mass effect is dominant in standard ECRIS installations with stainless steel plasma chambers. In order to gain more insight into the physics of the gas mixing effect and in particular on the relevance of the dilution process, we have carried out a study where we have investigated the role of the plasma-wall interaction on the gas mixing effect. In this contribution, we shall discuss Charge state distributions spectra, measured at the Frankfurt ECRIS using different working gases, pure argon, a mixture of argon and oxygen, and argon mixed with neon.

  10. Nature of Surface Changes in Stamping Tools of Gray and Ductile Cast Iron During Gas and Plasma Nitrocarburizing

    NASA Astrophysics Data System (ADS)

    Roli?ski, E.; Konieczny, A.; Sharp, G.

    2009-11-01

    Two cast irons, pearlitic-ferritic gray and ferritic ductile, were plasma and gas nitrocarburized at the same temperature and for the same processing time to produce a compound zone of about 10-14 ?m thick. It was demonstrated that both processes caused changes in the surface roughness of the irons, and the most dramatic increase of roughness was observed after gas nitrocarburizing of the gray cast iron. It was shown that the primary reason that the results were not the same is the difference in the nitriding mechanism. Significant penetration of the surface voids and imperfections between the graphite particles and the metallic matrix by ammonia molecules led to the formation of a locally thicker compound zone and a bulging of the metallic matrix above the surface. This phenomenon did not occur in the plasma process and as a result the surface changes were much smaller than in the gas process.

  11. A simple thermodynamic model of diluted hydrogen gas/plasma for CFD applications

    NASA Astrophysics Data System (ADS)

    Quartapelle, L.; Muzzio, A.

    2015-06-01

    This work describes a simple thermodynamic model of the hydrogen gas at low densities and for temperatures going from those involving quantum rotations of ortho- and para-hydrogen up to the fully ionized state. The closed-form energy levels of Morse rotating oscillator given [D.C. Harris, M.D. Bertolucci, Symmetry and Spectroscopy (Dover, New York, 1989)] (but not those in Morse's original paper) are shown to provide an internal partition function of H2 that is a sufficiently accurate representation of that exploiting the state-of-the-art spectrum of roto-vibrational levels calculated by Pachucki and Komasa [K. Pachucki, J. Komasa, J. Chem. Phys. 130, 164113 (2009)]. A system of two coupled quadratic equations for molecular dissociation and atomic ionization at thermodynamical and chemical equilibrium is derived according to the statistical mechanics by assuming that the system is an ideal mixture containing molecules, neutral atoms and noninteracting protons and electrons. The system of two equations reduces to a single quartic equation for the ionization unknown, with the coefficients dependent on the temperature and the specific volume. Explicit relations for specific energy and entropy of the hydrogen ideal gas/plasma model are derived. These fully compatible equations of state provide a complete thermodynamic description of the system, uniformly valid from low temperatures up to a fully ionized state, with electrons and ions relaxed to one and the same temperature. The comparison with results of other models developed in the framework of the physical and chemical pictures shows that the proposed elementary model is adequate for computational fluid dynamics purposes, in applications with the hydrogen gas under diluted conditions and when the dissociation and ionization can be assumed at thermodynamical and chemical equilibrium.

  12. The plasma line revisited as an aeronomical diagnostic - Suprathermal electrons, solar EUV, electron-gas thermal balance

    NASA Technical Reports Server (NTRS)

    Carlson, H. C., Jr.; Mantas, G. P.; Wickwar, V. B.

    1977-01-01

    Spectra of plasma wave intensities in the ionosphere over Arecibo are calculated and compared with those from observations of the plasma line intensity. This approach involving directly observed quantities avoids the uncertainties that have plagued past comparisons with photoelectron theory. In addition, careful comparisons in physically relevant segments of the spectra show that any significant increase in the magnitude of the solar EUV flux would lead to a contradiction of the observed plasma wave intensities. Further, the comparisons indicate that resolution of the thermal electron-gas heat balance problem must be sought through better heat transfer rates (e.g., heating and cooling rates, etc.), rather than in the solar EUV. This approach utilizes more fully the potential of the plasma line experiment as a diagnostic tool for aeronomical studies, (e.g., photoelectrons, auroral secondaries, ionosphere-modification experiments, etc.).

  13. 9 CFR 109.2 - Sterilizers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STERILIZATION AND PASTEURIZATION AT LICENSED ESTABLISHMENTS § 109.2 Sterilizers. Steam and dry-heat...

  14. Assessment of Residual Moisture and Maintenance of Sterility in Surgical Instrument Sets after Sterilization.

    PubMed

    Fayard, Camille; Lambert, Christophe; Guimier-Pingault, Catherine; Levast, Marion; Germi, Raphaelle

    2015-08-01

    Good sterilization practices include discarding items containing residual moisture after steam sterilization. In this small laboratory study, however, the presence of residual water did not appear to compromise the sterility of surgical instruments in 2 commonly used types of packaging during routine storage after steam sterilization. Infect Control Hosp Epidemiol 2015;36(8):990-992. PMID:25990555

  15. Genetic Basis of the Sterile Insect Technique

    Microsoft Academic Search

    A. S. ROBINSON

    The use of the sterile insect technique (SIT) for insect control relies on the introduction of sterility in the females of the wild population. This sterility is produced following the mating of these females with released males carrying, in their sperm, dominant lethal mutations that have been induced by ionizing radiation. The reasons why the SIT can only be effective

  16. Unintended Pregnancy Prevention: Female Sterilization

    MedlinePLUS

    ... of questions about menstruation did the researchers ask women in this study? Women in the study were asked several questions about their most recent ... had bleeding or spotting between periods. Did the study only include women who had undergone tubal sterilization? No. Changes in ...

  17. Solvent-modified solid-phase microextraction for the determination of diazepam in human plasma samples by capillary gas chromatography.

    PubMed

    Krogh, M; Grefslie, H; Rasmussen, K E

    1997-02-21

    This paper describes microextraction and gas chromatographic analysis of diazepam from human plasma. The method was based on immobilisation of 1.5 microliters of 1-octanol on a polyacrylate-coated fiber designed for solid-phase microextraction. The solvent-modified fibre was used to extract diazepam from the samples. The plasma sample was pre-treated to release diazepam from the protein binding. The fibre was inserted into the modified plasma sample, adjusted to pH 5.5 an internal standard was added and the mixture was carefully stirred for 4 min. The fibre with the immobilised solvent and the enriched analytes was injected into the capillary gas chromatograph. The solvent and the extracted analytes were evaporated at 300 degrees C in the split-splitless injection port of the gas chromatograph, separated on a methylsilicon capillary column and detected with a nitrogen-phosphorus detector. The method was shown to be reproducible with a detection limit of 0.10 nmol/ml in human plasma. PMID:9080322

  18. Plasma Channels for Electron Accelerators Using Discharges in Structured Gas Cells

    Microsoft Academic Search

    Rodolfo A. Bendoyro; Roxana I. Onofrei; João Sampaio; Rita Macedo; Gonçalo Figueira; Nelson C. Lopes

    2008-01-01

    We present a new scheme to produce preformed plasma waveguides to extend the acceleration length of laser-plasma accelerators. The plasma is produced in a hydrogen background by a high-voltage discharge between two hollow conic electrodes through a sequence of thin dielectric plates with apertures that fix the initial plasma diameter and position. The thickness of the dielectric plates is close

  19. Novel implant for transcervical sterilization.

    PubMed

    Rehan, Muhammad; Coleman, James; Olabi, Abdul Ghani

    2010-08-01

    Compared to laparoscopic surgery for interval tubal sterilization, the transcervical approach is an effective method of female sterilization which obviates the requirement of general anesthesia and surgical incision. However, current methods of transcervical sterilization are unable to provide an instant occlusion. This paper focuses on the design, development and testing of a novel implant (James E., Coleman, Christy Cummins, 2009. Anastomosis Devices and Method. US Patent 20090105733A1) to achieve instant permanent female sterilization via the transcervical approach. The implant is designed to be deployed under hysteroscopic visualization into the ostium of the fallopian tube and relies on instant mechanical occlusion. The implant includes two sets of wings that penetrate into the ostium and uterine muscle tissue and trap the tissue in between thus plugging the entrance of the fallopian tube. In order to design the shape of implant wings and to investigate the mechanical behavior of the implant, a three-dimensional (3D) model was developed and Finite Element Method (FEM) was used for simulations. The implant was validated by a number of successful deployments in bench testing, animal tissue and explanted human uteri. During the deployments in animal tissue and explanted uteri, it was observed that the two sets of wings completely trapped the tissue in between and the hydraulic pressure testing of the explanted uteri using saline solution and methylene blue proved the instant occlusion of the fallopian tubes. Initial results suggest that this novel implant provides a safe and effective method of female sterilization. Further development work is ongoing in preparation for "first-in-man" clinical trials. PMID:20547383

  20. Study on the Removal of SO2 from Simulated Flue Gas Using Dry Calcium-Spray with DBD Plasma

    NASA Astrophysics Data System (ADS)

    Yi, Chengwu; Wu, Chundu; Chen, Zhigang; Ou, Hongxiang; Shao, Xuejun

    2008-02-01

    In this study, lime-hydrate (Ca(OH)2) desulfurizer was treated by plasma with strong ionization discharge of a dielectric barrier. The removal of SO2 from simulated flue gas was investigated. The principles of SO2 removal are discussed. Several factors affecting the efficiency of SO2 removal were studied. They included the ratio of calcium to sulfur (Ca/S), desulfurizer granularity, residence time of the flue gas, voltage applied to the discharge electrode in the plasma generator, and energy consumption. Experimental results indicate that the increase in Ca/S ratio, the applied voltage and discharge power, the residence time, and the reduction in the desulfurizer granularity all can raise the SO2 removal efficiency. The SO2 removal efficiency was up to 91.3% under the following conditions, namely a primary concentration of SO2 of 2262 × 10-6 (v/v) in the emission gas, 21%(v/v) of oxygen, 1.8% (v/v) of water, a Ca/S ratio of 1.48, a residence time of 2.8 s, a 3.4 kV voltage and a 10 kHz frequency power applied to the discharge electrodes in the plasma generator, and a flow rate of 100 m3/h for emission gas.

  1. Evolution from a Molecular Rydberg Gas to an Ultracold Plasma in a Seeded Supersonic Expansion of NO

    SciTech Connect

    Morrison, J. P.; Rennick, C. J.; Keller, J. S.; Grant, E. R. [Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z3 (Canada)

    2008-11-14

    We report the spontaneous formation of a plasma from a gas of cold Rydberg molecules. Double-resonant laser excitation promotes nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, to single Rydberg states extending as deep as 80 cm{sup -1} below the lowest ionization threshold. The density of excited molecules in the illuminated volume approaches 1x10{sup 13} cm{sup -3}. This population evolves to produce free electrons and a durable cold plasma of electrons and intact NO{sup +} ions.

  2. Effect of adding oxygen gas to a high power nitrogen microwave-induced plasma for atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Ohata, Masaki; Ota, Hironobu; Fushimi, Motohiro; Furuta, Naoki

    2000-10-01

    In order to investigate the effect of adding oxygen gas (O 2) to a high power nitrogen microwave-induced plasma (N 2-MIP: 2.45 GHz, surface wave mode) for atomic emission spectrometry, the signal intensities for atom and ion lines of Ca, V, Ti, Mg, and Cd were observed by adding O 2 gas into N 2 outer gas in a range from 0 to 20%. From the observation of the background spectrum in a wavelength range of 200-400 nm, it was found that NO band spectra were enhanced largely with an increase in the addition of O 2 gas. The excitation temperatures ( Tex) observed decreased from 5500 to 4800 K with an increase in the percentage of adding O 2 gas from 0 to 20%. The relatively large signal enhancement was observed for all atom lines of Ca, V, Ti, Mg, and Cd when O 2 gas was added to N 2 outer gas. The emission signals for some of ion lines of Ca, V, Ti, and Mg also showed a signal enhancement when a small amount of O 2 gas was added. It was considered that the reason for the enhancement phenomena of the ion lines of these elements was attributed to the mechanism of the charge transfer reaction.

  3. A rapid analysis of plasma/serum ethylene and propylene glycol by headspace gas chromatography.

    PubMed

    Ehlers, Alexandra; Morris, Cory; Krasowski, Matthew D

    2013-12-01

    A rapid headspace-gas chromatography (HS-GC) method was developed for the analysis of ethylene glycol and propylene glycol in plasma and serum specimens using 1,3-propanediol as the internal standard. The method employed a single-step derivitization using phenylboronic acid, was linear to 200 mg/dL and had a lower limit of quantitation of 1 mg/dL suitable for clinical analyses. The analytical method described allows for laboratories with HS-GC instrumentation to analyze ethanol, methanol, isopropanol, ethylene glycol, and propylene glycol on a single instrument with rapid switch-over from alcohols to glycols analysis. In addition to the novel HS-GC method, a retrospective analysis of patient specimens containing ethylene glycol and propylene glycol was also described. A total of 36 patients ingested ethylene glycol, including 3 patients who presented with two separate admissions for ethylene glycol toxicity. Laboratory studies on presentation to hospital for these patients showed both osmolal and anion gap in 13 patients, osmolal but not anion gap in 13 patients, anion but not osmolal gap in 8 patients, and 1 patient with neither an osmolal nor anion gap. Acidosis on arterial blood gas was present in 13 cases. Only one fatality was seen; this was a patient with initial serum ethylene glycol concentration of 1282 mg/dL who died on third day of hospitalization. Propylene glycol was common in patients being managed for toxic ingestions, and was often attributed to iatrogenic administration of propylene glycol-containing medications such as activated charcoal and intravenous lorazepam. In six patients, propylene glycol contributed to an abnormally high osmolal gap. The common presence of propylene glycol in hospitalized patients emphasizes the importance of being able to identify both ethylene glycol and propylene glycol by chromatographic methods. PMID:23741644

  4. Fundamental Processes in A general definition of a plasma is: plasma is an ionized gas or other medium

    E-print Network

    Callen, James D.

    particle. Thus, the trajectory of a charged test particle is influenced by many simultaneous, small angle is an ionized gas or other medium in which charged particle interactions are predominantly collective. In a neutral gas the particle interactions are dominated by isolated, distinct two-particle (binary) collisions

  5. Bisexual Hybrid Sterility in DROSOPHILA MELANOGASTER

    PubMed Central

    Colgan, D. J.; Angus, D. S.

    1978-01-01

    A new type of hybrid sterility was investigated in D. melanogaster . Matings between strain 27 males from Para Wirra, South Australia, and Canton-S females produce 70–80% fully sterile male and female progeny. Strain 27 males produce sterile progeny when crossed to females of other geographic origins, but produce fertile progeny when crossed to a second sympatric strain. The sterility is avoided by lower rearing temperatures. Heat shock and tetracycline produce no improvement in the fertility of the hybrids. Normal flies produce sterile progeny when injected with, or fed, homogenates of sterile flies. A combination of maternal and paternal factors may interact to produce sterile hybrids by inhibiting gonad development. PMID:17248832

  6. Microwave Sterilization and Depyrogenation System

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

    2009-01-01

    A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time at a given flow rate. These technologies can be employed in small-scale systems for efficient production of MGW in the laboratory or in a range of larger systems that meet various industrial requirements. The microwave antennas can also be adapted to selectively sterilize vulnerable connections to ultra-pure water production facilities or biologically vulnerable systems where microorganisms may intrude.

  7. On the interplay of gas dynamics and the electromagnetic field in an atmospheric Ar/H2 microwave plasma torch

    NASA Astrophysics Data System (ADS)

    Synek, Petr; Obrusník, Adam; Hübner, Simon; Nijdam, Sander; Zají?ková, Lenka

    2015-04-01

    A complementary simulation and experimental study of an atmospheric pressure microwave torch operating in pure argon or argon/hydrogen mixtures is presented. The modelling part describes a numerical model coupling the gas dynamics and mixing to the electromagnetic field simulations. Since the numerical model is not fully self-consistent and requires the electron density as an input, quite extensive spatially resolved Stark broadening measurements were performed for various gas compositions and input powers. In addition, the experimental part includes Rayleigh scattering measurements, which are used for the validation of the model. The paper comments on the changes in the gas temperature and hydrogen dissociation with the gas composition and input power, showing in particular that the dependence on the gas composition is relatively strong and non-monotonic. In addition, the work provides interesting insight into the plasma sustainment mechanism by showing that the power absorption profile in the plasma has two distinct maxima: one at the nozzle tip and one further upstream.

  8. Influence of wall-charge accumulation on the gas dielectric barrier discharge in alternating current plasma display panel

    SciTech Connect

    Guo Bingang; Wei Wei; Shinoda, Tsutae; Liu Chunliang [Advanced Display Research Center, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba Meguro-Ku, Tokyo 153-8505 (Japan); Key Laboratory for Physical Electronics and Devices of the Ministry of Education of China, Xi'an Jiaotong University, Xi'an, Shaanxi Province, 710049 (China)

    2007-03-05

    Influences of wall-charge accumulation on gas dielectric barrier discharge (DBD) breakdown threshold and sustaining voltage margin of alternating current plasma display panel (AC-PDP) were investigated. It is observed that wall-charge accumulation results in a remarkable increase of gas DBD breakdown threshold during sustaining discharge period. Sustaining voltage margin is reduced by the threshold increase. A larger margin can be obtained when the threshold is decreased by removing unfavorable influence of wall-charge accumulation. Compared with normal margin, improved margin has a larger value and a faster linear increase with increasing wall-charge voltage. That indicates a way to improve AC-PDP performances remarkably.

  9. Influence of dust-particle concentration on gas-discharge plasma

    SciTech Connect

    Sukhinin, G. I. [Institute of Thermophysics SB RAS, Lavrentyev Avenue 1, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090 (Russian Federation); Fedoseev, A. V. [Institute of Thermophysics SB RAS, Lavrentyev Avenue 1, Novosibirsk 630090 (Russian Federation)

    2010-01-15

    A self-consistent kinetic model of a low-pressure dc glow discharge with dust particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the dust-particle surface and on the discharge tube wall were taken into account. The influence of dust-particle concentration N{sub d} on gas discharge and dust particles parameters was investigated. It is shown that the increase of N{sub d} leads to the increase of an averaged electric field and ion density, and to the decrease of a dust-particle charge and electron density in the dusty cloud. The results were obtained in a wide region of different discharge and dusty plasma parameters: dust particles density 10{sup 2}-10{sup 8} cm{sup -3}, discharge current density 10{sup -1}-10{sup 1} mA/cm{sup 2}, and dust particles radius 1, 2, and 5 mum. The scaling laws for dust-particle surface potential and electric filed dependencies on dust-particle density, particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the dust particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of dust particles and discharge parameters.

  10. Friction and wear performance of diamondlike carbon films grown in various source gas plasmas

    SciTech Connect

    Erdemir, A.; Nilufer, I. B.; Eryilmaz, O. L.; Beschliesser, M.; Fenske, G. R.

    2000-01-18

    In this study, the authors investigated the effects of various source gases (methane, ethane, ethylene, and acetylene) on the friction and wear performance of diamondlike carbon (DLC) films prepared in a plasma enhanced chemical vapor deposition (PECVD) system. Films were deposited on AISI H13 steel substrates and tested in a pin-on-disk machine against DLC-coated M50 balls in dry nitrogen. They found a close correlation between friction coefficient and source gas composition. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios exhibited lower friction coefficients and higher wear resistance than films grown in source gases with lower hydrogen-to-carbon (H/C) ratios. The lowest friction coefficient (0.014) was achieved with a film derived from methane with an WC ratio of 4, whereas the coefficient of films derived from acetylene (H/C = 1) was of 0.15. Similar correlations were observed for wear rates. Specifically, films derived from gases with lower H/C values were worn out and the substrate material was exposed, whereas films from methane and ethane remained intact and wore at rates that were nearly two orders of magnitude lower than films obtained from acetylene.

  11. Plasma steam reforming of E85 for hydrogen rich gas production

    NASA Astrophysics Data System (ADS)

    Zhu, Xinli; Hoang, Trung; Lobban, Lance L.; Mallinson, Richard G.

    2011-07-01

    E85 (85 vol% ethanol and 15 vol% gasoline) is a partly renewable fuel that is increasing in supply availability. Hydrogen production from E85 for fuel cell or internal combustion engine applications is a potential method for reducing CO2 emissions. Steam reforming of E85 using a nonthermal plasma (pulse corona discharge) reactor has been exploited at low temperature (200-300 °C) without external heating, diluent gas, oxidant or catalyst in this work. Several operational parameters, including the discharge current, E85 concentration and feed flow rate, have been investigated. The results show that hydrogen rich gases (63-67% H2 and 22-29% CO, with small amounts of CO2, C2 hydrocarbons and CH4) can be produced by this method. A comparison with ethanol reforming and gasoline reforming under identical conditions has also been made and the behaviour of E85 reforming is found to be close to that of ethanol reforming with slightly higher C2 hydrocarbons yields.

  12. Influence of dust-particle concentration on gas-discharge plasma.

    PubMed

    Sukhinin, G I; Fedoseev, A V

    2010-01-01

    A self-consistent kinetic model of a low-pressure dc glow discharge with dust particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the dust-particle surface and on the discharge tube wall were taken into account. The influence of dust-particle concentration N(d) on gas discharge and dust particles parameters was investigated. It is shown that the increase of N(d) leads to the increase of an averaged electric field and ion density, and to the decrease of a dust-particle charge and electron density in the dusty cloud. The results were obtained in a wide region of different discharge and dusty plasma parameters: dust particles density 10(2)-10(8) cm(-3), discharge current density 10(-1)-10(1) mA/cm(2), and dust particles radius 1, 2, and 5 microm. The scaling laws for dust-particle surface potential and electric filed dependencies on dust-particle density, particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the dust particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of dust particles and discharge parameters. PMID:20365480

  13. Plasma Studies in a High Pressure Gas Filled Radio Frequency Cavity

    NASA Astrophysics Data System (ADS)

    Freemire, Ben; Chung, Moses; Tollestrup, Alvin; Yonehara, Katsuya

    2014-10-01

    A Muon Collider offers a great deal of physics potential to the high energy physics community. In order to build such a machine with the desired luminosity, significant cooling of the muon beam is required. One proposed method for doing so is the Helical Cooling Channel, which consists of high pressure gas filled radio frequency (HPRF) cavities arranged in a helix within a strong external magnetic field. To validate this technology, an HPRF cavity was subjected to a 400 MeV proton beam at Fermilab's MuCool Test Area. Parent gases of hydrogen, deuterium, helium and nitrogen, at room temperature and densities up to 2.5E21 cm-3 were used, and doped with sulfur hexafluoride or dry air. The plasma density created by the beam approached 1E16 cm-3. Measurements of the RF energy dissipated per charged particle pair, the electron-ion recombination rate, the ion-ion recombination rate, and electron attachment time were made.

  14. Gas convection caused by electron pressure drop in the afterglow of a pulsed inductively coupled plasma discharge

    SciTech Connect

    Cunge, G.; Vempaire, D.; Sadeghi, N. [Laboratoire des Technologies de la Microelectronique, CEA-LETI, CNRS, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2010-03-29

    Neutral depletion is an important phenomenon in high-density plasmas. We show that in pulsed discharges, the neutral depletion caused by the electron pressure P{sub e} plays an important role on radical transport. In the afterglow, P{sub e} drops rapidly by electron cooling. So, a neutral pressure gradient built up between the plasma bulk and the reactor walls, which forces the cold surrounding gas to move rapidly toward the reactor center. Measured drift velocity of Al atoms in the early afterglow of Cl{sub 2}/Ar discharge by time-resolved laser induced fluorescence is as high as 250 ms{sup -1}. This is accompanied by a rapid gas cooling.

  15. Design and initial results from a kilojoule level Dense Plasma Focus with hollow anode and cylindrically symmetric gas puff.

    PubMed

    Ellsworth, J L; Falabella, S; Tang, V; Schmidt, A; Guethlein, G; Hawkins, S; Rusnak, B

    2014-01-01

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ?6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 10(7) per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results. PMID:24517762

  16. Determination of trace levels of water in solid samples by evolved gas analysis/helium microwave plasma emission spectrometry

    SciTech Connect

    Hanamura, S.; Kirsch, B.; Winefordner, J.D.

    1985-01-01

    A method for the determination of traces of adsorbed and/or bound water in solid samples is developed. This method is made up of the combination of thermal gas evolution and helium microwave plasma emission spectrometry. The solid sample is placed in a quartz crucible which is heated electrically in a He gas flow system by a programmed power supply. Vaporized H/sub 2/O is carried into the plasma, and the atomic emission line intensities of O and H are simultaneously measured by two spectrometers. Peak areas of oxygen and hydrogen are used to measure the concentration of H/sub 2/O in the sample. A known volume of H/sub 2/O is used for calibration. Several sample analyses are performed. 9 references, 8 figures, 7 tables.

  17. Element-selective detection of gas chromatographic eluates by near infrared Échelle optical emission spectrometry on microwave-induced plasmas

    NASA Astrophysics Data System (ADS)

    Koch, J.; Okruss, M.; Franzke, J.; Florek, S. V.; Niemax, K.; Becker-Ross, H.

    2004-02-01

    Specific analytical characteristics of near-infrared Échelle microwave-induced plasma atomic emission spectrometry (NIR-Échelle-MIP-OES) with respect to the quantification of organic compounds were examined. Matrices consisting of halogenated and sulfureous hydrocarbons were gas chromatographically separated and subsequently H-, C-, F-, Cl-, Br-, I- and S-selectively analyzed. For these purposes, a compact Échelle spectrometer, designed for the high-repetitive, high-resolved and simultaneous spectra acquisition between 640 and 990 nm was used. Depending on the plasma gas applied and element considered, detection limits typically varied from 200-2200 pg/s for Ar to 70-660 pg/s for He. Furthermore, strategies to improve the over-all sensitivity are discussed. In this context, a concept, which rests on simultaneous multi-line analysis is described and experimentally proofed.

  18. Design and initial results from a kilojoule level dense plasma focus with hollow anode and cylindrically symmetric gas puff

    SciTech Connect

    Ellsworth, J. L., E-mail: ellsworth7@llnl.gov; Falabella, S.; Tang, V.; Schmidt, A.; Guethlein, G.; Hawkins, S.; Rusnak, B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

    2014-01-15

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ?6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 10{sup 7} per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results.

  19. Design and initial results from a kilojoule level dense plasma focus with hollow anode and cylindrically symmetric gas puff

    NASA Astrophysics Data System (ADS)

    Ellsworth, J. L.; Falabella, S.; Tang, V.; Schmidt, A.; Guethlein, G.; Hawkins, S.; Rusnak, B.

    2014-01-01

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ˜6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 107 per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results.

  20. Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work

    Microsoft Academic Search

    I. O. Golosnoy; A. Cipitria; T. W. Clyne

    2009-01-01

    A review is presented of how heat transfer takes place in plasma-sprayed (zirconia-based) thermal barrier coatings (TBCs) during operation of gas turbines. These characteristics of TBCs are naturally of central importance to their function. Current state-of-the-art TBCs have relatively high levels of porosity (~15%) and the pore architecture (i.e., its morphology, connectivity, and scale) has a strong influence on the

  1. Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work

    Microsoft Academic Search

    I. O. Golosnoy; A. Cipitria; T. W. Clyne

    2009-01-01

    A review is presented of how heat transfer takes place in plasma-sprayed (zirconia-based) thermal barrier coatings (TBCs)\\u000a during operation of gas turbines. These characteristics of TBCs are naturally of central importance to their function. Current\\u000a state-of-the-art TBCs have relatively high levels of porosity (~15%) and the pore architecture (i.e., its morphology, connectivity,\\u000a and scale) has a strong influence on the

  2. Determination of lorazepam in plasma and urine as trimethylsilyl derivative using gas chromatography–tandem mass spectrometry

    Microsoft Academic Search

    S. Pichini; R. Pacifici; I. Altieri; A. Palmeri; M. Pellegrini; P. Zuccaro

    1999-01-01

    A procedure based on gas chromatography–tandem mass spectrometry for identification and quantitation of lorazepam in plasma and urine is presented. The analyte was extracted from biological fluids under alkaline conditions using solid-phase extraction with an Extrelut-1 column in the presence of oxazepam-d5 as the internal standard. Both compounds were then converted to their trimethylsilyl derivatives and the reaction products were

  3. Characterization of multicapillary gas chromatography–microwave-induced plasma atomic emission spectrometry for the expeditious analysis for organometallic compounds

    Microsoft Academic Search

    Isaac Rodriguez Pereiro; Andrzej Wasik; Ryszard ?obi?ski

    1998-01-01

    Multicapillary column gas chromatography (MC-GC)–microwave-induced plasma atomic emission spectrometry (MIP-AES) is evaluated for fast speciation analysis of organometallic compounds. In situ derivatized organomercury, organotin and organolead compounds are separated isothermally within several seconds instead of several minutes required by the conventional procedures. Neither the resolution nor the sample capacity are sacrificed compared with conventional capillary GC with oven temperature gradient

  4. Determination of polychlorinated biphenyls in biotic matrices using gas chromatography-microwave-induced plasma atomic emission spectrometry

    Microsoft Academic Search

    Jana Hajšlová; Petr Cuhra; Milan Kempný; Jan Poustka; Kate?ina Holadová; Vladimír Kocourek

    1995-01-01

    Basic parameters associated with practical application of gas chromatography coupled with microwave-induced plasma atomic emission spectrometric detection GC-MIP-AED in the determination of seven “indicator” polychlorinated biphenyls (PCBs) in biotic matrices were evaluated. The detection limit for chlorine (Cl-479) was found to be 0.54 pg\\/s. Under the conditions used for sample analysis (1 ?l of purified extract injected into the GC-MIP-AED

  5. Emission characteristics and parameters of gas-discharge plasma in mixtures of heavy inert gases with chlorine

    Microsoft Academic Search

    A. K. Shuaibov; A. N. Malinin

    2009-01-01

    The ultraviolet (UV) radiation from longitudinal glow-discharge plasma in three- and four-component mixtures of argon, krypton,\\u000a and xenon with chlorine has been investigated. The total radiation of Ar, Kr, and Xe monochlorides and chlorine molecules\\u000a in the spectral range 170–310 nm has been optimized with respect to the composition and the pressure of gas mixtures, as well\\u000a as the discharge

  6. Emission characteristics and parameters of gas-discharge plasma in mixtures of heavy inert gases with chlorine

    Microsoft Academic Search

    A. K. Shuaibov; A. N. Malinin

    2009-01-01

    The ultraviolet (UV) radiation from longitudinal glow-discharge plasma in three- and four-component mixtures of argon, krypton, and xenon with chlorine has been investigated. The total radiation of Ar, Kr, and Xe monochlorides and chlorine molecules in the spectral range 170-310 nm has been optimized with respect to the composition and the pressure of gas mixtures, as well as the discharge

  7. Method of sterilization using ozone

    NASA Technical Reports Server (NTRS)

    Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor)

    2002-01-01

    Methods of using ozone have been developed which sterilize instruments and medical wastes, oxidize, organics found in wastewater, clean laundry, break down contaminants in soil into a form more readily digested by microbes, kill microorganisms present in food products, and destroy toxins present in food products. The preferred methods for killing microorganism and destroying toxins use pressurized, humidified, and concentrated ozone produced by an electrochemical cell.

  8. Study of pulsed soft X-ray source employing a gas-puff Z-pinch plasma device for lithography applications

    Microsoft Academic Search

    G. X. Zhang; X. M. Guo; C. M. Luo; S. Lee; X. Feng

    1997-01-01

    Employing a gas-puff Z-pinch plasma device, we have developed a bright and reliable X-ray source. The Z-pinch plasma was produced by a capacity discharge, using a fast valve to inject an annulus of Argon gas. The total capacitance of circuit is 24muF, and the peak discharge current is 360kA with a quarter-period of 2mus when the capacitor bank was charged

  9. Deuterium thermal desorption from carbon based materials: A comparison of plasma exposure, ion implantation, gas loading, and C-D codeposition

    NASA Astrophysics Data System (ADS)

    Pisarev, A.; Gasparyan, Yu.; Rusinov, A.; Trifonov, N.; Kurnaev, V.; Spitsyn, A.; Khripunov, B.; Schwarz-Selinger, T.; Rasinski, M.; Sugiyama, K.

    2011-08-01

    Thermal desorption spectra from fine grain graphite and carbon fiber composite exposed in different plasma installations have been compared with those obtained after ion implantation, absorption from gas, and those from soft and hard C-D films. Features of the spectra were analysed and led to the conclusion that ion implantation, absorption from gas, and amorphous C:D layer formed on the surface contribute to trapping during plasma irradiation.

  10. Effects of Radius, Microwave Power, and Gas Flow Rate on the Electronic Excitation Temperature in an Atmospheric Pressure Microwave Plasma Torch

    Microsoft Academic Search

    Karyn M. Green

    The microwave plasma continuous emissions monitor (MP-CEM) utilizes atomic emis- sion spectroscopy to study trace quantities of hazardous metals such as mercury and lead. With the aim of improving the MP-CEM sensitivity to these metals, a series of experiments are performed to characterize this microwave plasma operating at atmospheric pressure. All experiments use air as the working gas. Assuming local

  11. Process Study of Silicon Carbide Coatings Deposited on Steel by Plasma-Assisted Chemical Vapor Deposition from Tetramethylsilane-Argon Gas System

    Microsoft Academic Search

    Wei Zhang; Marc Lelogeais; Michel Ducarroir

    1992-01-01

    Silicon carbide coatings were prepared in an RF plasma-assisted chemical vapor deposition (CVD) device from the tetramethylsilane-argon gas system. The present paper is devoted to investigation of the plasma process and determination of the deposition rate with the experimental parameters. By employing the general convective diffusion equation, we obtain a simple analytical expression of the deposition rate. Calculated results are

  12. Development of a sterilizing in-place application for a production machine using Vaporized Hydrogen Peroxide.

    PubMed

    Mau, T; Hartmann, V; Burmeister, J; Langguth, P; Häusler, H

    2004-01-01

    The use of steam in sterilization processes is limited by the implementation of heat-sensitive components inside the machines to be sterilized. Alternative low-temperature sterilization methods need to be found and their suitability evaluated. Vaporized Hydrogen Peroxide (VHP) technology was adapted for a production machine consisting of highly sensitive pressure sensors and thermo-labile air tube systems. This new kind of "cold" surface sterilization, known from the Barrier Isolator Technology, is based on the controlled release of hydrogen peroxide vapour into sealed enclosures. A mobile VHP generator was used to generate the hydrogen peroxide vapour. The unit was combined with the air conduction system of the production machine. Terminal vacuum pumps were installed to distribute the gas within the production machine and for its elimination. In order to control the sterilization process, different physical process monitors were incorporated. The validation of the process was based on biological indicators (Geobacillus stearothermophilus). The Limited Spearman Karber Method (LSKM) was used to statistically evaluate the sterilization process. The results show that it is possible to sterilize surfaces in a complex tube system with the use of gaseous hydrogen peroxide. A total microbial reduction of 6 log units was reached. PMID:15233253

  13. Performance evaluation of non-thermal plasma injection for elemental mercury oxidation in a simulated flue gas.

    PubMed

    An, Jiutao; Shang, Kefeng; Lu, Na; Jiang, Yuze; Wang, Tiecheng; Li, Jie; Wu, Yan

    2014-03-15

    The use of non-thermal plasma (NTP) injection approach to oxidize elemental mercury (Hg(0)) in simulated flue gas at 110°C was studied, where a surface discharge plasma reactor (SDPR) inserted in the simulated flue duct was used to generate and inject active species into the flue gas. Approximately 81% of the Hg(0) was oxidized and 20.5?gkJ(-1) of energy yield was obtained at a rate of 3.9JL(-1). A maximal Hg(0) oxidation efficiency was found with a change in the NTP injection air flow rate. A high Hg(0) oxidation efficiency was observed in the mixed flue gas that included O2, H2O, SO2, NO and HCl. Chemical and physical processes (e.g., ozone, N2 metastable states and UV-light) were found to contribute to Hg(0) oxidation, with ozone playing a dominant role. The deposited mercury species on the internal surface of the flue duct was analyzed using X-ray photoelectron spectroscopy (XPS) and electronic probe microanalysis (EPMA), and the deposit was identified as HgO. The mercury species is thought to primarily exist in the form of HgO(s) by adhering to the suspended aerosols in the gas-phase. PMID:24513449

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

    SciTech Connect

    Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady, E-mail: gennady@purdue.edu; Hassanein, Ahmed [Center for Materials Under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-04-15

    Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1?atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1?atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures.

  15. Scaling behavior of ultrafast two-color terahertz generation in plasma gas targets: energy and pressure dependence.

    PubMed

    Rodriguez, George; Dakovski, Georgi L

    2010-07-01

    Ultrafast terahertz emission from two-color generated laser plasma gas targets is studied using air and the noble gases (neon, argon, krypton, and xenon) as the generation media. Terahertz output pulse energy and power spectra are measured as function of gas species, gas pressure, and input pulse energy up to 6 mJ per pulse using a 40-fs 1-kHz Ti:sapphire laser system as the drive source. Terahertz pulse energies approaching 1 microJ per pulse with spectral content out to 40 THz and pulse duration of 35 fs is reported. A simple one dimensional transient photocurrent ionization model is used to calculate the spectra showing good agreement with experiments. PMID:20639998

  16. Effect of O 2(CO 2)\\/C 4F 8O gas combinations on global warming gas emission in silicon nitride PECVD plasma cleaning

    Microsoft Academic Search

    B. H. Oh; J. W. Bae; J. H. Kim; K. J. Kim; Y. S. Ahn; N.-E. Lee; G. Y. Yeom; S. S. Yoon; S.-K. Chae; M.-S. Ku; S.-G. Lee; D.-H. Cho

    2001-01-01

    In this study, O2\\/C4F8O and CO2\\/C4F8O have been used as the chemicals for plasma-enhanced chemical vapor deposition (PECVD) chamber-cleaning of silicon nitride, and the effects of gas mixture and operational pressure on the silicon-nitride cleaning rate and emission properties, such as emission species, destruction and removal efficiencies (DREs), and million metric tons of carbon equivalent (MMTCE), have been investigated. O2\\/C4F8O

  17. A novel low-jitter plasma-jet triggered gas switch operated at a low working coefficient

    NASA Astrophysics Data System (ADS)

    Tie, Weihao; Liu, Shanhong; Liu, Xuandong; Zhang, Qiaogen; Pang, Lei; Liu, Longchen

    2014-02-01

    In this paper, we described the fabrication and testing of a novel plasma-jet triggered gas switch (PJTGS) operated at extremely low working coefficients with excellent triggered jitters. While the structure of the PJTGS is similar to that of a traditional three-electrode field-distortion gas switch, to improve its triggered performance we used a conical micro-plasma-gun with a needle-to-plate spark gap embedded in the trigger electrode. Applying a nanosecond pulse to the trigger electrode caused a spark discharge in the micro-plasma-gun. The electric field drove the discharge plasma to spray into the spark gap of the gas switch, causing fast breakdown. We tested the PJTGS with charging voltages of ±25 kV and a trigger voltage of +80 kV (5 ns rise time and 80 ns full width at half maximum) in two working modes. The PJTGS operated in Mode II had a lower triggered jitter and could be operated over a wider range of working coefficients than in Mode I under the same conditions. At working coefficients higher than 70%, we obtained sub-ns triggered jitters (<0.89 ns) from the PJTGS, at working coefficients lower than 50%, we obtained triggered jitters of 1.6-3.5 ns without no-fires or pre-fires. Even at a working coefficient of 27.4%, the PJTGS could still be triggered reliably with a delay time of 96.1 ns and a triggered jitter of 3.5 ns, respectively.

  18. Radiation sterilization of new drug delivery systems

    PubMed Central

    Abuhano?lu, Gürhan

    2014-01-01

    Radiation sterilization has now become a commonly used method for sterilization of several active ingredients in drugs or drug delivery systems containing these substances. In this context, many applications have been performed on the human products that are required to be sterile, as well as on pharmaceutical products prepared to be developed. The new drug delivery systems designed to deliver the medication to the target tissue or organ, such as microspheres, nanospheres, microemulsion, and liposomal systems, have been sterilized by gamma (?) and beta (?) rays, and more recently, by e-beam sterilization. In this review, the sterilization of new drug delivery systems was discussed other than conventional drug delivery systems by ? irradiation. PMID:24936306

  19. Improving the ethylene oxide sterilization process.

    PubMed

    Berth, L; Wolffbrandt, K H

    1992-01-01

    Although ethylene oxide (EtO) sterilization is commonly used in the manufacture of sterile medical devices, concern about residues of the sterilant in the sterilized products has led to an increase in the use of alternative methods; however, these methods, in turn, have significant drawbacks. The authors have tackled the issue by looking into the possibility of reducing EtO residuals. After conducting a series of investigative experiments, it has been proved that EtO residuals may be reduced by decreasing the amount of EtO used in the sterilization process. This can be achieved without lowering the safe sterility level and there are additional benefits for safety, cost, and the environment. PMID:10171589

  20. Surgical sterilization, regret, and race: contemporary patterns.

    PubMed

    Shreffler, Karina M; McQuillan, Julia; Greil, Arthur L; Johnson, David R

    2015-03-01

    Surgical sterilization is a relatively permanent form of contraception that has been disproportionately used by Black, Hispanic, and Native American women in the United States in the past. We use a nationally representative sample of 4592 women ages 25-45 to determine whether sterilization continues to be more common and consequential by race for reproductive-age women. Results indicate that Native American and Black women are more likely to be sterilized than non-Hispanic White women, and Hispanic and Native American women are more likely than non-Hispanic White women to report that their sterilization surgeries prevent them from conceiving children they want. Reasons for sterilization differ significantly by race. These findings suggest that stratified reproduction has not ended in the United States and that the patterns and consequences of sterilization continue to vary by race. PMID:25592919

  1. Establishment of very uniform gas-flow pattern in the process chamber for microwave-excited high-density plasma by ceramic shower plate

    SciTech Connect

    Goto, Tetsuya; Inokuchi, Atsutoshi; Ishibashi, Kiyotaka; Yasuda, Seij; Nakanishi, Toshio; Kohno, Masayuki; Okesaku, Masahiro; Sasaki, Masaru; Nozawa, Toshihisa; Hirayama, Masaki; Ohmi, Tadahiro [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan); Tokyo Electron Ltd., Tokyo 107-6325 (Japan); Tokyo Electron Technology Development Institute, Inc., Hyogo 660-0891 (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan); Tokyo Electron AT Ltd., Hyogo 660-0891 (Japan); Hokuriku Seikei Industrial, Co., Ltd., Ishikawa 923-0157 (Japan); Tokyo Electron Technology Development Institute, Inc., Hyogo 660-0891 (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan)

    2009-07-15

    The authors developed a ceramic upper shower plate used in the microwave-excited high-density plasma process equipment incorporating a dual shower-plate structure to establish a very uniform gas-flow pattern in the process chamber. Thousands of very fine gas-injection holes are implemented on this Al{sub 2}O{sub 3} upper shower plate with optimized allocation to establish a uniform gas-flow pattern of plasma-excitation gases and radical-generation gases for generating intended radicals in the plasma-excitation region. The size of these fine holes must be 50 {mu}m or less in diameter and 8 mm or more in length because these holes perform an essential role: They completely avoid the plasma excitation in these fine holes and upper gas-supply regions resulting from the plasma penetration into these regions from excited high-density plasma, even if very high-density plasma greater than 1x10{sup 12} cm{sup -3} is excited just under the ceramic upper shower plate by microwaves supplied from the radial line slot antenna. On the other hand, various process gases, such as material gases for film formations and etching gases, are supplied from the lower shower plate installed in the diffusion plasma region to this very uniform gas-flow pattern region of plasma-excitation gases and radical-generation gases. As a result, the process gases are supplied to the wafer surface in a very effective manner without excess decomposition of those process gas molecules and undesired reaction-product deposition on the inner surface of the process chamber. The process results are improved drastically by introducing the newly developed ceramic upper shower plate. But also, process uniformity on the entire wafer is improved with drastically reducing reaction-product deposition on the inner surface of the process chamber.

  2. Effect of sterilization method on properties of Palacos R acrylic bone cement.

    PubMed

    Lewis, G; Mladsi, S

    1998-01-01

    The focus of this work was a delineation of the effect of the method of sterilization (gamma-irradiation versus exposure to ethylene oxide (EtO) gas) of the powder constituents of Palacos R bone cement on the molecular weight, quasi-static tensile and compressive properties and fatigue performance of the fully polymerized material. It was found that the quasi-static properties are not noticeably affected. However, when the powder constituents were gamma-sterilized, both the molecular weight and the fatigue performance of the cement are significantly lower compared to when the constituents are EtO-sterilized. Explanations are offered for these findings, and recommendations are submitted regarding the preferred method of sterilization of bone cement and reporting of studies in which different formulations of cement are compared. PMID:9678858

  3. Safe storage times for sterile instrument packs.

    PubMed

    Schwartz, R S; Butt, W E; Bradley, D V; Mayhew, R B

    1992-08-01

    Military health care facilities are required to place expiration dates on sterile instrument packs. There are few scientific guidelines for determining these dates. This article reports the findings of two studies conducted at Wilford Hall USAF Medical Center, which investigated the potential shelf-life of three packaging materials for sterile instruments. The results of the studies indicate that sterility is maintained for at least 1 year with all three materials. The maximum storage times allowed for sterile instruments at most military facilities appear to be overly restrictive. PMID:1528486

  4. Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D

    SciTech Connect

    Wesley, J; Hollmann, E; Jernigan, T; Van Zeeland, M; Baylor, L; Boedo, J; Combs, S; Evans, T; Groth, M; Humphreys, D; Hyatt, A; Izzo, V; James, A; Moyer, R; Parks, P; Rudakov, D; Strait, E; Wu, W; Yu, J

    2008-10-14

    Massive gas injection (MGI) experiments with H{sub 2}, D{sub 2}, He, Ne and Ar and 'mixed' (H{sub 2} + Ar and D{sub 2} + Ne) gases injected into 'ITER-similar' 1.3-MA H-mode plasmas are described. Gas species, injected quantity Q, delivery time, t{sub inj}, rate-of-rise and intrinsic and added impurities are found to affect the attributes and 'disruption mitigation' efficacies of the resulting fast plasma shutdowns. With sufficient Q and t{sub inj} < {approx}2 ms, all species provide fast (within {le} {approx}3 ms), more-or-less uniform radiative dissipation of the 0.7-MJ plasma thermal energy and fast but benign current decays with reduced vacuum vessel vertical force impulse. With pure and mixed low-Z gases, free-electron densities up to 2 x 10{sup 21} m{sup -3} are obtained. While these densities are high relative to normal tokamak densities, they are still an order of magnitude smaller than the densities required for unconditional mitigation of the runaway electron avalanche process. Key information relevant to the design of effective MGI systems for larger tokamaks and ITER has been obtained and the collective species and Q-variation data provides a rich basis for validation of emerging 2D + t MHD/transport/radiation models.

  5. AURORA: A FORTRAN program for modeling well stirred plasma and thermal reactors with gas and surface reactions

    SciTech Connect

    Meeks, E.; Grcar, J.F.; Kee, R.J. [Sandia National Labs., Livermore, CA (United States). Thermal and Plasma Processes Dept.] [Sandia National Labs., Livermore, CA (United States). Thermal and Plasma Processes Dept.; Moffat, H.K. [Sandia National Labs., Albuquerque, NM (United States). Surface Processing Sciences Dept.] [Sandia National Labs., Albuquerque, NM (United States). Surface Processing Sciences Dept.

    1996-02-01

    The AURORA Software is a FORTRAN computer program that predicts the steady-state or time-averaged properties of a well mixed or perfectly stirred reactor for plasma or thermal chemistry systems. The software was based on the previously released software, SURFACE PSR which was written for application to thermal CVD reactor systems. AURORA allows modeling of non-thermal, plasma reactors with the determination of ion and electron concentrations and the electron temperature, in addition to the neutral radical species concentrations. Well stirred reactors are characterized by a reactor volume, residence time or mass flow rate, heat loss or gas temperature, surface area, surface temperature, the incoming temperature and mixture composition, as well as the power deposited into the plasma for non-thermal systems. The model described here accounts for finite-rate elementary chemical reactions both in the gas phase and on the surface. The governing equations are a system of nonlinear algebraic relations. The program solves these equations using a hybrid Newton/time-integration method embodied by the software package TWOPNT. The program runs in conjunction with the new CHEMKIN-III and SURFACE CHEMKIN-III packages, which handle the chemical reaction mechanisms for thermal and non-thermal systems. CHEMKIN-III allows for specification of electron-impact reactions, excitation losses, and elastic-collision losses for electrons.

  6. Analytical performance of a low-gas-flow torch optimized for inductively coupled plasma atomic emission spectrometry

    USGS Publications Warehouse

    Montaser, A.; Huse, G.R.; Wax, R.A.; Chan, S.-K.; Golightly, D.W.; Kane, J.S.; Dorrzapf, A.F., Jr.

    1984-01-01

    An inductively coupled Ar plasma (ICP), generated in a lowflow torch, was investigated by the simplex optimization technique for simultaneous, multielement, atomic emission spectrometry (AES). The variables studied included forward power, observation height, gas flow (outer, intermediate, and nebulizer carrier) and sample uptake rate. When the ICP was operated at 720-W forward power with a total gas flow of 5 L/min, the signal-to-background ratios (S/B) of spectral lines from 20 elements were either comparable or inferior, by a factor ranging from 1.5 to 2, to the results obtained from a conventional Ar ICP. Matrix effect studies on the Ca-PO4 system revealed that the plasma generated in the low-flow torch was as free of vaporizatton-atomizatton interferences as the conventional ICP, but easily ionizable elements produced a greater level of suppression or enhancement effects which could be reduced at higher forward powers. Electron number densities, as determined via the series until line merging technique, were tower ht the plasma sustained in the low-flow torch as compared with the conventional ICP. ?? 1984 American Chemical Society.

  7. On sterile and hybrid pheasants

    Microsoft Academic Search

    Geoffrey Smith; Haig Thomas

    1913-01-01

    Summary  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a Evidence is brought forward to show that the sterility of the male and female hybrid pheasants is due to abnormalities occurring\\u000a at the synapsis stage of the reduction division.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a The spermatozoa of the hybrids are either deformed, with chromatic beads and thickenings on them, or else of abnormal size,\\u000a double-sized spermatozoa being of frequent occurrence as in

  8. An alternative method for gas temperature determination in nitrogen plasmas: Fits of the bands of the first positive system (B 3?g-->A 3?u+)

    NASA Astrophysics Data System (ADS)

    Biloiu, Costel; Sun, Xuan; Harvey, Zane; Scime, Earl

    2007-04-01

    A method of gas temperature determination in nitrogen or nitrogen doped discharges is presented. The method employs fits of numerically generated spectra of the 0-0, 1-0, and 2-0 bands of the first positive system (B ?3g?A ?3u +) of nitrogen to experimental measurements. Excellent agreement between gas temperature values inferred by using this method and by using the 3-0 band peak ratio method [M. Simek and S. De Benedictis, Plasma Chem. Plasma Proc. 15, 451 (1995)] is demonstrated for a helicon plasma. The spectral model is available for use by the plasma spectroscopy community. The model, along with user instructions, can be downloaded from Electronic Physics Auxiliary Publication Service of American Institute of Physics. The model includes the line positions, Hönl-London factors, and provides rapid determination of gas temperature if one or more of the aforementioned emission rovibrational band spectra are available.

  9. Determination of gas temperature and thermometric species in inductively coupled plasmas by emission and diode laser absorption

    NASA Astrophysics Data System (ADS)

    Bol'shakov, Alexander A.; Cruden, Brett A.; Sharma, Surendra P.

    2004-11-01

    A vertical cavity surface-emitting laser diode (VCSEL) was used as a spectrally tunable emission source for measurements of the radial-integrated gas temperature inside an inductively coupled plasma reactor. The data were obtained by profiling the Doppler-broadened absorption of metastable Ar atoms at 763.51 nm in argon and argon/nitrogen plasmas (3%, 45%, and 90% N2 in Ar) at pressures of 0.5-70 Pa and inductive powers of 100 and 300 W. The results were compared to the rotational temperature derived from the N2 emission at the (0,0) vibrational transition of the C 3?u-B 3? g system. The differences in integrated rotational and Doppler temperatures were attributed to non-uniform spatial distributions of both temperature and thermometric species (Ar* and N_{2}^* ) that varied depending on the conditions. A two-dimensional, three-temperature fluid plasma simulation was employed to explain these differences. This work should facilitate further development of a miniature sensor for non-intrusive acquisition of data (temperature and densities of multiple plasma species) during micro- and nano-fabrication plasma processing, thus enabling diagnostic-assisted continuous optimization and advanced control over the processes. Such sensors would also enable us to track the origins and pathways of damaging contaminants, thereby providing real-time feedback for adjustment of processes. Our work serves as an example of how two line-of-sight integrated temperatures derived from different thermometric species make it possible to characterize the radial non-uniformity of the plasma.

  10. An helium microwave-induced plasma Fourier transform atomic emission spectrometer as a novel two-dimensional detector for gas chromatography

    SciTech Connect

    Bailey, T.D.

    1989-01-01

    The helium microwave-induced plasma (MIP) emission excitation source is a sensitive, element selective detector for gas chromatography. Fourier transform (FT) spectrometry is a technique that allows rapid simultaneous monitoring of the full spectrum of a light source. The combination of the MIP excitation course with an FT spectrometer provides a versatile simultaneous multielement gas chromatography detector. The design and construction of a helium microwave-induced plasma/Fourier transform atomic emission detector for gas chromatography is described. Examples of the operation of this instrument are given.

  11. Effects of gas composition, focus ring and blocking capacitor on capacitively coupled RF Ar/H2 plasmas

    NASA Astrophysics Data System (ADS)

    Tong, Lizhu

    2015-06-01

    The capacitively coupled discharges in Ar/H2 mixtures operating at a RF frequency of 13.56 MHz and the total gas pressure of 100 Pa are investigated by means of a two-dimensional fluid model, in which a blocking capacitor is serially connected to the power electrode. The gas mixtures of Ar with 0–10% H2 and the blocking capacitors of 1 and 100 nF are taken into account. The applied voltage is 200 V and the gas temperature is considered to be 300 K. The density profiles of all the plasma species in the discharges are obtained. Results show that the plasma discharge is concentrated over the focus ring, not being in the center of the reactor. A large potential difference and a high capacitive power deposition appear at the surface area between the substrate and focus ring. With the addition of small amount of H2 to Ar, the electron density markedly decreases. It is found that the reductions of the metastable excited argon density and the metastable pooling ionization rate due to the addition of H2 are the main reason that causes the electron density decrease. The self DC-bias generated by the blocking capacitor is examined.

  12. 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

  13. Overview of plasma technology used in medicine

    NASA Astrophysics Data System (ADS)

    Ryan, Thomas P.; Stalder, Kenneth R.; Woloszko, Jean

    2013-02-01

    Plasma Medicine is a growing field that is having an impact in several important areas in therapeutic patient care, combining plasma physics, biology, and clinical medicine. Historically, plasmas in medicine were used in electrosurgery for cautery and non-contact hemostasis. Presently, non-thermal plasmas have attained widespread use in medicine due to their effectiveness and compatibility with biological systems. The paper will give a general overview of how low temperature, non-equilibrium, gas plasmas operate, both from physics and biology perspectives. Plasma is commonly described as the fourth state of matter and is typically comprised of charged species, active molecules and atoms, as well as a source of UV and photons. The most active areas of plasma technology applications are in wound treatment; tissue regeneration; inactivation of pathogens, including biofilms; treating skin diseases; and sterilization. There are several means of generating plasmas for use in medical applications, including plasma jets, dielectric barrier discharges, capacitively or inductively coupled discharges, or microplasmas. These systems overcome the former constraints of high vacuum, high power requirements and bulky systems, into systems that use room air and other gases and liquids at low temperature, low power, and hand-held operation at atmospheric pressure. Systems will be discussed using a variety of energy sources: pulsed DC, AC, microwave and radiofrequency, as well as the range of frequency, pulse duration, and gas combinations in an air environment. The ionic clouds and reactive species will be covered in terms of effects on biological systems. Lastly, several commercial products will be overviewed in light of the technology utilized, health care problems being solved, and clinical trial results.

  14. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Satoshi

    2013-07-01

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  15. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    SciTech Connect

    Hamaguchi, Satoshi [Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2013-07-11

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  16. Plasma convection induced by toroidal asymmetries of the divertor plates and gas puffing

    Microsoft Academic Search

    R. H. Cohen; D. D. Ryutov

    1997-01-01

    In the open field line region of the scrape-off layer (SOL), the plasma potential is to a considerable degree determined by the boundary conditions on the divertor plates. The idea is explored here that, by making the divertor plates slightly `wavy' in the toroidal direction, toroidally varying potentials can be produced throughout the SOL and thereby convective plasma motion induced.

  17. Optimization of a gas discharge plasma source for extreme ultraviolet interference lithography at a wavelength of 11 nm

    SciTech Connect

    Bergmann, K. [Fraunhofer Institute for Laser Technology, Steinbachstrasse 15, D-52074 Aachen (Germany); Danylyuk, S. V.; Juschkin, L. [Chair for Technology of Optical Systems, RWTH Aachen University and JARA Fundamentals of Future Information Technology, Steinbachstr. 15, 52074 Aachen (Germany)

    2009-10-01

    In this work, we report about the optimization of the spectral emission characteristic of a gas discharge plasma source for high-resolution extreme ultraviolet (EUV) interference lithography based on achromatic Talbot self-imaging. The working parameters of the source are optimized to achieve a required narrowband emission spectrum and to fulfill the necessary coherence and intensity requirements. The intense 4f-4d transitions around 11 nm in a highly ionized (Xe{sup 8+}-Xe{sup 12+}) xenon plasma are chosen to provide the working wavelength. This allows us to increase the available radiation intensity in comparison with an in-band EUV xenon emission at 13.5 nm and opens up the possibility to strongly suppress the influence of the 5p-4d transitions at wavelengths between 12 and 16 nm utilizing a significant difference in conditions for optical thickness between 4f-4d and 5p-4d transitions. The effect is achieved by using the admixture of argon to the pinch plasma, which allows keeping the plasma parameters approximately constant while, at the same time, reducing the density of xenon emitters. It is demonstrated that with this approach it is possible to achieve a high intensity 11 nm EUV radiation with a bandwidth of 3%-4% without the use of multilayer mirrors or other additional spectral filters in the vicinity of the working wavelength. The achieved radiation parameters are sufficient for high-performance interference lithography based on the achromatic Talbot effect.

  18. Comparative analysis of barium titanate thin films dry etching using inductively coupled plasmas by different fluorine-based mixture gas

    PubMed Central

    2014-01-01

    In this work, the inductively coupled plasma etching technique was applied to etch the barium titanate thin film. A comparative study of etch characteristics of the barium titanate thin film has been investigated in fluorine-based (CF4/O2, C4F8/O2 and SF6/O2) plasmas. The etch rates were measured using focused ion beam in order to ensure the accuracy of measurement. The surface morphology of etched barium titanate thin film was characterized by atomic force microscope. The chemical state of the etched surfaces was investigated by X-ray photoelectron spectroscopy. According to the experimental result, we monitored that a higher barium titanate thin film etch rate was achieved with SF6/O2 due to minimum amount of necessary ion energy and its higher volatility of etching byproducts as compared with CF4/O2 and C4F8/O2. Low-volatile C-F compound etching byproducts from C4F8/O2 were observed on the etched surface and resulted in the reduction of etch rate. As a result, the barium titanate films can be effectively etched by the plasma with the composition of SF6/O2, which has an etch rate of over than 46.7 nm/min at RF power/inductively coupled plasma (ICP) power of 150/1,000 W under gas pressure of 7.5 mTorr with a better surface morphology. PMID:25278821

  19. Steam quality and effective sterilization.

    PubMed

    Sedlacek, R S; Rose, E F

    1985-01-01

    Faced with using steam from a commercial utility having boilers greater than 5 miles distant and being the last user on the system resulted in ineffective sterilization. A three phase testing program was established utilizing: Direct physical measurements - an Ellison model 915A portable steam calorimeter. Direct microbiology - Autoclaved feed pellets were aseptically placed in fluid thioglycolate medium and incubated at 37 degrees C. Indirect microbiology - Feces from "defined flora" mice fed the autoclaved pelleted feed were tested. Colorimetric measurements verified that the steam sometimes contained greater than 5% entrained water. During periods of wet steam it was impossible to maintain consistent sterility of the mouse pellets even using a cycle of 126 degrees C for 60 minutes. One spore-forming Gram positive rod, Clostridium perfringens type D was the predominant bacterium isolated. Lactating mice, or mice stressed experimentally came down with diarrhea within days of eating pellets treated with wet steam (calorimetric measurements) and a subsequent positive culture. These mice voided stools predominantly showing Clostridium perfringens type D. PMID:2862643

  20. Measurement of 3-nitro-tyrosine in human plasma and urine by gas chromatography-tandem mass spectrometry.

    PubMed

    Tsikas, Dimitrios; Mitschke, Anja; Gutzki, Frank-Mathias

    2012-01-01

    Reaction of reactive nitrogen species (RNS), such as peroxynitrite and nitryl chloride with soluble tyrosine and tyrosine residues in proteins produces soluble 3-nitro-tyrosine and 3-nitro-tyrosino-proteins, respectively. Regular proteolysis of 3-nitro-tyrosino-proteins yields soluble 3-nitro-tyrosine. 3-Nitro-tyrosine circulates in plasma and is excreted in the urine. Both circulating and excretory 3-nitro-tyrosine are considered suitable biomarkers of nitrative stress. Tandem mass spectrometry coupled with gas chromatography (GC-MS/MS) or liquid chromatography (LC-MS/MS) is one of the most reliable analytical techniques to determine 3-nitro-tyrosine. Here, we describe protocols for the quantitative determination of soluble 3-nitro-tyrosine in human plasma and urine by GC-MS/MS. PMID:22125150

  1. Application of a high-density gas laser target to the physics of x-ray lasers and coronal plasmas

    SciTech Connect

    Pronko, J.G.; Kohler, D.

    1996-05-31

    An experiment has been proposed to investigate a photopumped x-ray laser approach using a novel, high-density, laser heated supersonic gas jet plasma to prepare the lasant plasma. The scheme uses the He- like sodium 1.10027 nm line to pump the He-like neon 1s-4p transition at 1.10003 nm with the lasing transitions between the n=4 to n=2,3 states and the n=3 to n=2 state at 5.8 nm, 23.0 nm, and 8.2 nm, respectively. The experiment had been proposed in 1990 and funding began Jan. 1991; however circumstances made it impossible to pursue the research over the past 5 years, and it was decided not to pursue the research any further.

  2. Determination of nifedipine and its three principal metabolites in plasma and urine by automated electron-capture capillary gas chromatography.

    PubMed

    Schmid, B J; Perry, H E; Idle, J R

    1988-03-01

    A sensitive, efficient, linear and reproducible capillary gas chromatographic method with electron-capture detection was developed for the quantitation of nifedipine and its primary metabolite M-I in plasma together with the urinary and principal metabolites M-II and M-III. On-column, rather than split-splitless, injection was employed to obviate oxidative degradation of nifedipine to M-I. The photosensitivity of nifedipine was re-examined under laboratory conditions and nifedipine was found to have a half-life in excess of two days when amber glassware and darkroom manipulations under red light were used. The method can determine nifedipine and its metabolites in plasma and urine after a single oral dose of 5 mg and can be applied to measure M-I production by human liver microsomes. PMID:3360861

  3. Emission characteristics and parameters of gas-discharge plasma in mixtures of heavy inert gases with chlorine

    NASA Astrophysics Data System (ADS)

    Shuaibov, A. K.; Malinin, A. N.

    2009-04-01

    The ultraviolet (UV) radiation from longitudinal glow-discharge plasma in three- and four-component mixtures of argon, krypton, and xenon with chlorine has been investigated. The total radiation of Ar, Kr, and Xe monochlorides and chlorine molecules in the spectral range 170-310 nm has been optimized with respect to the composition and the pressure of gas mixtures, as well as the discharge current. The mean output power, the electric power of discharge, and the efficiency of a broadband low-pressure exciplex halogen lamp have been determined. Parameters of the glow discharge in Ar-Kr-Cl2 and Kr-Xe-Cl2 mixtures have been simulated numerically. The electron energy distribution functions have been determined through the solution of the Boltzmann kinetic equation. These functions have been used to calculate the plasma parameters, namely, electron transfer characteristics, specific losses of discharge power for electronic processes, and ionization and attachment coefficients.

  4. 21 CFR 880.2800 - Sterilization process indicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Sterilization process indicator. 880.2800 Section 880.2800 Food... § 880.2800 Sterilization process indicator. (a) Biological sterilization process indicator —(1) Identification. A...

  5. 21 CFR 522.1484 - Neomycin sulfate sterile solution.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... false Neomycin sulfate sterile solution. 522.1484 Section 522.1484...522.1484 Neomycin sulfate sterile solution. (a) Specifications. Each milliliter of sterile aqueous solution contains 50 milligrams of...

  6. 21 CFR 522.1484 - Neomycin sulfate sterile solution.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... false Neomycin sulfate sterile solution. 522.1484 Section 522.1484...522.1484 Neomycin sulfate sterile solution. (a) Specifications. Each milliliter of sterile aqueous solution contains 50 milligrams of...

  7. Sterilization using high-pressure carbon dioxide

    Microsoft Academic Search

    Jian Zhang; Thomas A. Davis; Michael A. Matthews; Michael J. Drews; Martine LaBerge; Yuehuei H. An

    2006-01-01

    Sterility is required for medical devices use in invasive medical procedures, and for some situations in the food industry. Sterilization of heat-sensitive or porous materials or devices, such as endoscopes, porous implants, liquid foodstuff, and liquid medicine, poses a challenge to current technologies. There has been a steady interest in using high-pressure carbon dioxide as a process medium for new

  8. Effective terminal sterilization using supercritical carbon dioxide

    Microsoft Academic Search

    Angela White; David Burns; Tim W. Christensen

    2006-01-01

    Gentle alternatives to existing sterilization methods are called for by rapid advances in biomedical technologies. Supercritical fluid technologies have found applications in a wide range of areas and have been explored for use in the inactivation of medical contaminants. In particular, supercritical CO2 is appealing for sterilization due to the ease at which the supercritical state is attained, the non-reactive

  9. On the Structure of the Two-Dimensional Spatially Periodic Inner Transition Layers in a Gas-Discharge Plasma

    SciTech Connect

    Voronov, A.Ya. [Russian Federal Nuclear Center, All-Russia Scientific-Research Institute of Experimental Physics, Sarov, Nizhni Novgorod oblast, 607190 (Russian Federation)

    2005-07-01

    We investigate the structure of the spatially periodic inner boundary layers in the plasma of a positive glow-discharge column produced in a long cylindrical tube with an electropositive gas inside. Asymptotic methods, namely, the method of boundary functions, are used to analyze the initial mathematical model. We consider the formation of contrast burst-type structures. We have found all principal terms of the boundary-layer asymptotics of the solution. The results obtained are compared with the available probe measurements of basic physical parameters of ionization waves (strata) in neon at low pressures.

  10. Table-top soft x-ray microscope using laser-induced plasma from a pulsed gas jet.

    PubMed

    Müller, Matthias; Mey, Tobias; Niemeyer, Jürgen; Mann, Klaus

    2014-09-22

    An extremely compact soft x-ray microscope operating in the "water window" region at the wavelength ? = 2.88 nm is presented, making use of a long-term stable and nearly debris-free laser-induced plasma from a pulsed nitrogen gas jet target. The well characterized soft x-ray radiation is focused by an ellipsoidal grazing incidence condenser mirror. Imaging of a sample onto a CCD camera is achieved with a Fresnel zone plate using magnifications up to 500x. The spatial resolution of the recorded microscopic images is about 100 nm as demonstrated for a Siemens star test pattern. PMID:25321818

  11. Development of a gas-based spectral filter for carbon dioxide laser produced plasma extreme ultraviolet sources

    NASA Astrophysics Data System (ADS)

    Mbanaso, Chimaobi

    Currently, extreme ultraviolet (EUV) lithography is a promising next generation lithography technique for enabling the scaling of device features beyond 22 nm. Out-of-band radiation in EUV exposure tools remains one of the critical issues that must be addressed before the implementation of this lithography technique for high volume manufacturing. Laser produced plasmas which use a carbon dioxide (CO2) drive laser pulse are more likely to be used to generate EUV radiation because of their scalability to higher source power. The out-of-band spectrum at the intermediate focus of EUV sources that use a CO2 laser produced plasma is dominated by scattered radiation from the drive laser which operates near 10.6 microm wavelength. The unmitigated infrared radiation causes deformation of the optics in the lithography scanner making it difficult to maintain stringent overlay specifications. EUV transmission losses incurred as a result of using existing solid filters is of concern due to the limited source power currently achievable in these exposure tools. This research work investigated the use of infrared absorbing gaseous species to spectrally reduce the unwanted CO2 laser light reaching the intermediate focus. The spectral attractiveness of an infrared absorbing gas, sulfur hexafluoride, was evaluated based on the measured absorption cross section at wavelengths around 13.5 nm and 10.6 mum in custom optical systems. Based on the results acquired from the built systems, it was possible to predict the suppression of infrared radiation near 10.6 mum wavelength as well as the EUV transmission losses as a function of different gas densities. As part of this work, gas-based diffusion barriers were considered for inhibiting the molecular transport of the infrared absorbing species to other regions of the EUV system. An experimental configuration equipped with a quadruple mass spectrometer was designed to characterize and test the functionality of a magnetically confined plasma discharge to inhibit gaseous transport. The results indicated ionization and directional molecular collisions as factors that contribute towards establishing a gas density gradient due to the presence of an argon plasma discharge.

  12. Electron energy distribution functions and transport coefficients relevant for air plasmas in the troposphere: impact of humidity and gas temperature

    NASA Astrophysics Data System (ADS)

    Gordillo-Vázquez, F. J.; Donkó, Z.

    2009-08-01

    A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25°S and +25°N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, ~215 K (at 11 km) and ~198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N <= 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas temperature is only slightly noticeable in the attachment coefficient that can exhibit an increase of up to one order of magnitude at 11 km and 15 km for temperatures of 313 K and 308 K, respectively. Finally, a brief analysis is carried out on the impact of the gas temperature on the diffusion coefficients of neutrals and ions. The present results show quite reasonable agreement with available measurements in dry and moist air.

  13. Production of fissioning uranium plasma to approximate gas-core reactor conditions

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Mcfarland, D. R.; Hohl, F.; Kim, K. H.

    1974-01-01

    The intense burst of neutrons from the d-d reaction in a plasma-focus apparatus is exploited to produce a fissioning uranium plasma. The plasma-focus apparatus consists of a pair of coaxial electrodes and is energized by a 25 kJ capacitor bank. A 15-g rod of 93% enriched U-235 is placed in the end of the center electrode where an intense electron beam impinges during the plasma-focus formation. The resulting uranium plasma is heated to about 5 eV. Fission reactions are induced in the uranium plasma by neutrons from the d-d reaction which were moderated by the polyethylene walls. The fission yield is determined by evaluating the gamma peaks of I-134, Cs-138, and other fission products, and it is found that more than 1,000,000 fissions are induced in the uranium for each focus formation, with at least 1% of these occurring in the uranium plasma.

  14. Plasma Processing with a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP)

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2000-10-01

    The vast majority of all industrial plasma processing is conducted with glow discharges at pressures below 10 torr. This has limited applications to high value workpieces as a result of the large capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role if they could be operated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) has been developed at the University of Tennessee Plasma Sciences Laboratory. The OAUGDP is non-thermal RF plasma with the time-resolved characteristics of a classical low pressure DC normal glow discharge. An interdisciplinary team was formed to conduct exploratory investigations of the physics and applications of the OAUGDP. This team includes collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC) and the Departments of Electrical and Computer Engineering, Microbiology, Food Science and Technology, and Mechanical and Aerospace Engineering and Engineering Science. Exploratory tests were conducted on a variety of potential plasma processing and other applications. These include the use of OAUGDP to sterilize medical and dental equipment and air filters; diesel soot removal; plasma aerodynamic effects; electrohydrodynamic (EDH) flow control of the neutral working gas; increasing the surface energy of materials; increasing the wettability and wickability of fabrics; and plasma deposition and directional etching. A general overview of these topics will be presented.

  15. Nonthermal plasma systems and methods for natural gas and heavy hydrocarbon co-conversion

    DOEpatents

    Kong, Peter C.; Nelson, Lee O.; Detering, Brent A.

    2005-05-24

    A reactor for reactive co-conversion of heavy hydrocarbons and hydrocarbon gases and includes a dielectric barrier discharge plasma cell having a pair of electrodes separated by a dielectric material and passageway therebetween. An inlet is provided for feeding heavy hydrocarbons and other reactive materials to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a variety of light sources for providing ultraviolet light within the discharge plasma cell. Methods for upgrading heavy hydrocarbons are also disclosed.

  16. Care and sterilization of endourologic instruments.

    PubMed

    Gregory, E; Simmons, D; Weinberg, J J

    1988-08-01

    All endourologic instruments must be handled properly if they are to continue to function properly. Care must be taken in washing and sterilizing of this equipment, as not all endoscopic equipment can endure all methods, and people who are working with these instruments must be taught the proper care and sterilization methods of each. For example, fiberoptic telescopes and light cables must never be autoclaved; ethylene oxide is the method of choice. Disinfectant is an alternative. Loops, sheaths, high-frequency cables, resectoscopes, and working elements should be sterilized by ethylene oxide. Loops and high-frequency cables should not be soaked in a disinfectant, but other instruments may be soaked. All instruments should be dried before sterilization. Too much emphasis cannot be placed on the importance of proper storage of these very fragile fiberoptic instruments. With proper care and sterilization, these instruments will need fewer repairs and function properly for a longer time. PMID:3407043

  17. Microstructure and properties of 17-4PH steel plasma nitrocarburized with a carrier gas containing rare earth elements

    SciTech Connect

    Liu, R.L., E-mail: ruiliangliu@126.com [National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yan, M.F., E-mail: yanmufu@hit.edu.cn [National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wu, Y.Q. [National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhao, C.Z. [College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin150001 (China)

    2010-01-15

    The effect of rare earth addition in the carrier gas on plasma nitrocarburizing of 17-4PH steel was studied. The microstructure and crystallographically of the phases in the surface layer as well as surface morphology of the nitrocarburized specimens were characterized by optical microscope, X-ray diffraction and scanning tunneling microscope, respectively. The hardness of the surface layer was measured by using a Vickers hardness test. The results show that the incorporation of rare earth elements in the carrier gas can increase the nitrocarburized layer thickness up to 55%, change the phase proportion in the nitrocarburized layer, refine the nitrides in surface layer, and increase the layer hardness above 100HV. The higher surface hardening effect after rare earth addition is caused by improvement in microstructure and change in the phase proportion of the nitrocarburized layer.

  18. Vehicle exhaust gas clearance by low temperature plasma-driven nano-titanium dioxide film prepared by radiofrequency magnetron sputtering.

    PubMed

    Yu, Shuang; Liang, Yongdong; Sun, Shujun; Zhang, Kai; Zhang, Jue; Fang, Jing

    2013-01-01

    A novel plasma-driven catalysis (PDC) reactor with special structure was proposed to remove vehicle exhaust gas. The PDC reactor which consisted of three quartz tubes and two copper electrodes was a coaxial dielectric barrier discharge (DBD) reactor. The inner and outer electrodes firmly surrounded the outer surface of the corresponding dielectric barrier layer in a spiral way, respectively. Nano-titanium dioxide (TiO2) film prepared by radiofrequency (RF) magnetron sputtering was coated on the outer wall of the middle quartz tube, separating the catalyst from the high voltage electrode. The spiral electrodes were designed to avoid overheating of microdischarges inside the PDC reactor. Continuous operation tests indicated that stable performance without deterioration of catalytic activity could last for more than 25 h. To verify the effectiveness of the PDC reactor, a non-thermal plasma(NTP) reactor was employed, which has the same structure as the PDC reactor but without the catalyst. The real vehicle exhaust gas was introduced into the PDC reactor and NTP reactor, respectively. After the treatment, compared with the result from NTP, the concentration of HC in the vehicle exhaust gas treated by PDC reactor reduced far more obviously while that of NO decreased only a little. Moreover, this result was explained through optical emission spectrum. The O emission lines can be observed between 870 nm and 960 nm for wavelength in PDC reactor. Together with previous studies, it could be hypothesized that O derived from catalytically O3 destruction by catalyst might make a significant contribution to the much higher HC removal efficiency by PDC reactor. A series of complex chemical reactions caused by the multi-components mixture in real vehicle exhaust reduced NO removal efficiency. A controllable system with a real-time feedback module for the PDC reactor was proposed to further improve the ability of removing real vehicle exhaust gas. PMID:23560062

  19. CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics

    SciTech Connect

    Kee, R.J.; Rupley, F.M.; Meeks, E.; Miller, J.A.

    1996-05-01

    This document is the user`s manual for the third-generation CHEMKIN package. CHEMKIN is a software package whose purpose is to facilitate the formation, solution, and interpretation of problems involving elementary gas-phase chemical kinetics. It provides a flexible and powerful tool for incorporating complex chemical kinetics into simulations of fluid dynamics. The package consists of two major software components: an Interpreter and a Gas-Phase Subroutine Library. The Interpreter is a program that reads a symbolic description of an elementary, user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Gas-Phase Subroutine Library. This library is a collection of about 100 highly modular FORTRAN subroutines that may be called to return information on equations of state, thermodynamic properties, and chemical production rates. CHEMKIN-III includes capabilities for treating multi-fluid plasma systems, that are not in thermal equilibrium. These new capabilities allow researchers to describe chemistry systems that are characterized by more than one temperature, in which reactions may depend on temperatures associated with different species; i.e. reactions may be driven by collisions with electrons, ions, or charge-neutral species. These new features have been implemented in such a way as to require little or no changes to CHEMKIN implementation for systems in thermal equilibrium, where all species share the same gas temperature. CHEMKIN-III now has the capability to handle weakly ionized plasma chemistry, especially for application related to advanced semiconductor processing.

  20. [Determination of 10 sedative-hypnotics in human plasma using pulse splitless injection technique and gas chromatography-mass spectrometry].

    PubMed

    Chang, Qing; Ma, Hongying; Wang, Fangjie; Ou, Honglian; Zou, Ming

    2011-11-01

    A simple, precise and sensitive gas chromatography-mass spectrometry (GC-MS) method coupled with pulse splitless injection technique was developed for the determination of 10 sedative-hypnotics (barbital, amobarbital, phenobarbital, oxazepam, diazepam, nitrazepam, clonazepam, estazolam, alprazolam, triazolam) in human plasma. The drugs spiked in plasma were extracted with ethyl acetate after alkalization with 0.1 mol/L NaOH solution. The organic solvent was evaporated under nitrogen stream, and the residues were redissolved by ethyl acetate. The separation was performed on an HP-5MS column (30 m x 250 microm x 0.25 microm). The analytes were determined and identified using selected ion monitoring (SIM) mode and scan mode, respectively. The internal standard method was used for the determination. The target analytes were well separated from each other on their SIM chromatograms and also on the total ion current (TIC) chromatograms. The blank extract from human plasma gave no peaks that interfered with all the analytes on the chromatogram. The calibration curves for 10 sedative-hypnotics showed excellent linearity. The correlation coefficients of all the drugs were higher than 0.9954. The recoveries of the drugs spiked in human plasma ranged from 92.28% to 111.7%, and the relative standard deviations (RSDs) of intra-day and inter-day determinations were from 4.09% to 14.26%. The detection limits ranged from 2 to 20 microg/L. The method is simple, reliable, rapid and sensitive for the determination and the quantification of 10 sedative-hypnotics in human plasma and seems to be useful in the practice of clinical toxicological cases. PMID:22393695

  1. Preparation of prereduced anaerobically sterilized media and their use in cultivation of anaerobic bacteria.

    PubMed Central

    Chan, E C; deVries, J; Harvey, R F

    1978-01-01

    Several modifications of the roll-tube method have made it simpler for routine use in the isolation and growth of anaerobic bacteria. These include use of a check valve for the production of prereduced anaerobically sterilized media; a Salvarsan tube under oxygen-free gas pressure for the dispensing of molten prereduced anaerobically sterilized agar medium; a Kelly infusion bottle with a graduated pipette side arm (also under gas pressure) for quantitative delivery of fluid prereduced anaerobically sterilized media; and screw-capped prescription bottles for the cultivation of anaerobes. Colonies of Bacteroides melaninogenicus were easily identified and counted by this method. Other anaerobic bacteria have also been cultivated successfully. Images PMID:29909

  2. Variation of soft X-ray emission with gas pressure in a plasma focus

    Microsoft Academic Search

    Chee Mang Ng; Siew Pheng Moo; Chiow San Wong

    1998-01-01

    The variation of the soft X-ray emission in a low energy (3 kJ, 15 kV) plasma focus over a range of pressures is investigated. The working gases are argon and an argon-hydrogen mixture. The X rays are detected using an assembly of PIN-Si diodes with differential filtering and with a multipinhole camera, soft X rays originating from the plasma and

  3. Fabrication of Polycrystalline Silicon Films from SiF4\\/H2\\/SiH4 Gas Mixture Using Very High Frequency Plasma Enhanced Chemical Vapor Deposition with {shape {In Situ}} Plasma Diagnostics and Their Structural Properties

    Microsoft Academic Search

    Kouichi Nakahata; Kazuyoshi Ro; Atsushi Suemasu; Toshio Kamiya; Charles Michael Fortmann; Isamu Shimizu

    2000-01-01

    Polycrystalline silicon (poly-Si) films were fabricated by very high frequency (VHF) plasma enhanced (PE) chemical vapor deposition (CVD) from SiF4 and H2 gas mixture with small amounts of SiH4. Reactions and growth of poly-Si in the SiF4\\/H2\\/SiH4 system were discussed together with the results obtained from in situ plasma diagnostics, and compared with those obtained by microwave PECVD (MW CVD).

  4. Vapor Hydrogen Peroxide Sterilization Certification

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Chung, Shirley; Barengoltz, Jack

    For interplanetary missions landing on a planet of potential biological interest, United States NASA planetary protection currently requires that the flight system must be assembled, tested and ultimately launched with the intent of minimizing the bioload taken to and deposited on the planet. Currently the only NASA approved microbial reduction method is dry heat sterilization process. However, with utilization of such elements as highly sophisticated electronics and sensors in modern spacecraft, this process presents significant materials challenges and is thus an undesirable bioburden reduction method to design engineers. The objective of this work is to introduce vapor hydrogen peroxide (VHP) as an alternative to dry heat microbial reduction to meet planetary protection requirements. The VHP sterilization technology is widely used by the medical industry, but high doses of VHP may degrade the performance of flight hardware, or compromise material compatibility. The goal of our study is determine the minimum VHP process conditions for PP acceptable microbial reduction levels. A series of experiments were conducted using Geobacillus stearothermophilus to determine VHP process parameters that provided significant reductions in spore viability while allowing survival of sufficient spores for statistically significant enumeration. In addition to the obvious process parameters -hydrogen peroxide concentration, number of pulses, and exposure duration -the investigation also considered the possible effect of environmental pa-rameters. Temperature, relative humidity, and material substrate effects on lethality were also studied. Based on the results, a most conservative D value was recommended. This recom-mended D value was also validated using VHP "hardy" strains that were isolated from clean-rooms and environmental populations collected from spacecraft relevant areas. The efficiency of VHP at ambient condition as well as VHP material compatibility will also be presented.

  5. Ultraviolet versus infrared: Effects of ablation laser wavelength on the expansion of laser-induced plasma into one-atmosphere argon gas

    NASA Astrophysics Data System (ADS)

    Ma, Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu, Jin; Lei, Wenqi; Bai, Xueshi; Zheng, Lijuan; Zeng, Heping

    2012-03-01

    Laser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV: 355 nm) or infrared (IR: 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy.

  6. Towards male sterility in Pinus radiata--a stilbene synthase approach to genetically engineer nuclear male sterility.

    PubMed

    Höfig, Kai P; Möller, Ralf; Donaldson, Lloyd; Putterill, Joanna; Walter, Christian

    2006-05-01

    A male cone-specific promoter from Pinus radiata D. Don (radiata pine) was used to express a stilbene synthase gene (STS) in anthers of transgenic Nicotiana tabacum plants, resulting in complete male sterility in 70% of transformed plants. Three plants were 98%-99.9% male sterile, as evidenced by pollen germination. To identify the stage at which transgenic pollen first developed abnormally, tobacco anthers from six different developmental stages were assayed microscopically. Following the release of pollen grains from tetrads, transgenic pollen displayed an increasingly flake-like structure, which gradually rounded up during the maturation process. We further investigated whether STS expression may have resulted in an impaired flavonol or sporopollenin formation. A specific flavonol aglycone stain was used to demonstrate that significant amounts of these substances were produced only in late stages of normal pollen development, therefore excluding a diminished flavonol aglycone production as a reason for pollen ablation. A detailed analysis of the exine layer by transmission electron microscopy revealed minor structural changes in the exine layer of ablated pollen, and pyrolysis-gas chromatography-mass spectroscopy indicated that the biochemistry of sporopollenin production was unaffected. The promoter-STS construct may be useful for the ablation of pollen formation in coniferous gymnosperms and male sterility may potentially be viewed as a prerequisite for the commercial use of transgenic conifers. PMID:17147639

  7. Microwave plasma assisted supersonic gas jet deposition of thin film materials

    DOEpatents

    Schmitt, III, Jerome J. (New Haven, CT); Halpern, Bret L. (Bethany, CT)

    1993-01-01

    An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

  8. Coupled two-dimensional edge plasma and neutral gas modeling of tokamak scrape-off-layers

    SciTech Connect

    Maingi, R. [North Carolina State Univ., Raleigh, NC (United States)

    1992-08-01

    The objective of this study is to devise a detailed description of the tokamak scrape-off-layer (SOL), which includes the best available models of both the plasma and neutral species and the strong coupling between the two in many SOL regimes. A good estimate of both particle flux and heat flux profiles at the limiter/divertor target plates is desired. Peak heat flux is one of the limiting factors in determining the survival probability of plasma-facing-components at high power levels. Plate particle flux affects the neutral flux to the pump, which determines the particle exhaust rate. A technique which couples a two-dimensional (2-D) plasma and a 2-D neutral transport code has been developed (coupled code technique), but this procedure requires large amounts of computer time. Relevant physics has been added to an existing two-neutral-species model which takes the SOL plasma/neutral coupling into account in a simple manner (molecular physics model), and this model is compared with the coupled code technique mentioned above. The molecular physics model is benchmarked against experimental data from a divertor tokamak (DIII-D), and a similar model (single-species model) is benchmarked against data from a pump-limiter tokamak (Tore Supra). The models are then used to examine two key issues: free-streaming-limits (ion energy conduction and momentum flux) and the effects of the non-orthogonal geometry of magnetic flux surfaces and target plates on edge plasma parameter profiles.

  9. Magnetically controlled deposition of metals using gas plasma. Grant final report, January 1994--September 1997

    SciTech Connect

    NONE

    1998-04-01

    This document reports the results of DOE grant DE-FE07-93ID3220 to the University of Idaho. The subject grant is the first phase of a project that has the objective to develop a method of spraying materials on a substrate in a controlled manner to eliminate the waste and hazardous material generation inherent in present plating processes. The project is considering plasma spraying of metal on a substrate using magneto-hydrodynamics to control the plasma/metal stream. The process being developed is considering the use of commercially available plasma torches to generate the plasma/metal stream. The plasma stream is collimated and directed using magnetic forces to the extent required for precise control of the deposition material. The plating process may be accomplished without waste and without generating hazardous waste. The project will be completed in phases. Phase one of the project, the subject of this grant, is the development of an analytical model that can be used to determine the feasibility of the process and to design a laboratory scale demonstration unit. The results of this phase of the project will provide clear data to demonstrate the theoretical feasibility of building and testing a laboratory demonstration unit. The contracted time is complete, and the research is still continuing. This report provides the results obtained to date. As the model and calculations are completed those results will also be provided.

  10. The Effects of Freeze-drying and Ethylene Oxide Sterilization on the Mechanical Properties of Human Patellar Tendon

    Microsoft Academic Search

    Joan E. Bechtold; D. Ted Eastlund; Michael K. Butts; David F. Lagerborg; Richard F. Kyle

    1994-01-01

    Human patellar tendon allografts are used to replace injured anterior cruciate ligaments. They are often stored by freeze-drying or freezing before use and have been sterilized by gamma irradiation or ethylene oxide gas. Studies comparing the mechanical properties of tendons preserved by freeze-drying and sterilized by ethylene oxide have yielded conflicting results. This study examined the effects of freeze-drying and

  11. Comparative assessment of different nonthermal plasma reactors on energy efficiency and aerosol formation from the decomposition of gas-phase benzene

    Microsoft Academic Search

    Hyun-Ha Kim; Hitomi Kobara; Atsushi Ogata; Shigeru Futamura

    2005-01-01

    This work presents a comparative assessment of five different types of plasma reactors (pulsed corona, dielectric-barrier discharge (DBD), surface discharge (SD), BaTiO3 packed-bed reactor, and plasma-driven catalyst (PDC) reactor) using the decomposition of gas-phase benzene. The parameters used in the assessment include energy constant, carbon balance, product selectivity, and nanometer-sized aerosol formation. The DBD reactor, the pulsed corona reactor, and

  12. Phosgene formation from the decomposition of 1,1-C 2H 2Cl 2 contained gas in an RF plasma reactor

    Microsoft Academic Search

    Wen-Jhy Lee; Chuh-Yung Chen; Wen-Chang Lin; Ying-Tang Wang; Ching-Ju Chin

    1996-01-01

    In this study, a radio-frequency (RF) plasma system was used to decompose the 1,1-dichloroethylene (DCE) contained gas. The reactants and final products were analyzed by using an FTIR (Fourier Transform Infrared Spectroscopy). The effect of plasma operational-parameters for DCE decomposition was evaluated. In addition, the possible reaction pathways for DCE decomposition and phosgene (COCl2) formation were built up and discussed.

  13. Basics of sterile compounding: bubble point testing.

    PubMed

    Thoma, Laura

    2014-01-01

    Compounding pharmacies that compound sterile preparations must choose sterile filters that are approved for human use. They may rely on the filter manufacturer's Certificate of Quality to ensure the sterile filter is pyrogen free and has been tested for bacterial retention. The Certificate of Quality from the filter manufacturer also contains other useful information about the filter such as: flow rate and maximum pressure drop, thermal and hydraulic stress, and membrane results of the initial integrity test performed on the filter membrane with water, if a hydrophilic membrane. This article discusses the integrity test, which is often called the water bubble point test. PMID:24881342

  14. Spore-Forming Bacteria that Resist Sterilization

    NASA Technical Reports Server (NTRS)

    LaDuc, Myron; Venkateswaran, Kasthuri

    2003-01-01

    A report presents a phenotypic and genotypic characterization of a bacterial species that has been found to be of the genus Bacillus and has been tentatively named B. odysseensis because it was isolated from surfaces of the Mars Odyssey spacecraft as part of continuing research on techniques for sterilizing spacecraft to prevent contamination of remote planets by terrestrial species. B. odysseensis is a Gram-positive, facultatively anaerobic, rod-shaped bacterium that forms round spores. The exosporium has been conjectured to play a role in the elevated resistance to sterilization. Research on the exosporium is proposed as a path toward improved means of sterilization, medical treatment, and prevention of biofouling.

  15. Quantification of nerolidol in mouse plasma using gas chromatography-mass spectrometry.

    PubMed

    Saito, Alexandre Yukio; Sussmann, Rodrigo Antonio Ceschini; Kimura, Emilia Akemi; Cassera, Maria Belen; Katzin, Alejandro Miguel

    2015-07-10

    Nerolidol is a naturally occurring sesquiterpene found in the essential oils of many types of flowers and plants. It is frequently used in cosmetics, as a food flavoring agent, and in cleaning products. In addition, nerolidol is used as a skin penetration enhancer for transdermal delivery of therapeutic drugs. However, nerolidol is hemolytic at low concentrations. A simple and fast GC-MS method was developed for preliminary quantification and assessment of biological interferences of nerolidol in mouse plasma after oral dosing. Calibration curves were linear in the concentration range of 0.010-5?g/mL nerolidol in mouse plasma with correlation coefficients (r) greater than 0.99. Limits of detection and quantification were 0.0017 and 0.0035?g/mL, respectively. The optimized method was successfully applied to the quantification of nerolidol in mouse plasma. PMID:25880240

  16. Behavior of a plasma in a high-density gas-embedded Z-pinch configuration

    SciTech Connect

    Shlachter, J.S.

    1982-05-01

    The theoretical analysis of a high density Z-pinch (HDZP) begins with an examination of the steady state energy balance between ohmic heating and bremsstrahlung radiation losses for a plasma column in pressure equilibrium. The model is then expanded to include the time-varying internal energy and results in a quasi-equilibrium prescription for the load current through a constant radius plasma channel. This set of current waveforms is useful in the design of experimental systems. The behavior of a plasma for physically realizable conditions is first examined by allowing adiabatic changes in the column radius. A more complete model is then developed by incorporating inertial effects into the momentum equation, and the resultant global MHD computational model is compared with more sophisticated, and costly, one- and two-dimensional computer simulations. These comparisons demonstrate the advantages of the global MHD description over previously developed zero-dimensional models.

  17. Gas purification by the plasma-oxidation of a rotating sacrificial electrode

    NASA Astrophysics Data System (ADS)

    Dahle, S.; Hirschberg, J.; Viöl, W.; Maus-Friedrichs, W.

    2015-06-01

    A novel approach for the purification of inert gases by means of a dielectric barrier discharge (DBD) plasma has been demonstrated for argon and nitrogen. A rotating sacrificial electrode has been employed together with an electrode cleaning system to remove passivating product films during the plasma processing and thus enhance capacity and reaction rates. The purification of nitrogen using this approach was shown to be quite successful. The conditioning of technical argon yielded rotational temperatures well beyond 150?°C, thus being unable to remove the water content effectively.

  18. Viscosity calculated in simulations of strongly coupled dusty plasmas with gas friction

    SciTech Connect

    Feng Yan; Goree, J.; Liu Bin [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

    2011-05-15

    A two-dimensional strongly coupled dusty plasma is modeled using Langevin and frictionless molecular dynamical simulations. The static viscosity {eta} and the wave-number-dependent viscosity {eta}(k) are calculated from the microscopic shear in the random motion of particles. A recently developed method of calculating the wave-number-dependent viscosity {eta}(k) is validated by comparing the results of {eta}(k) from the two simulations. It is also verified that the Green-Kubo relation can still yield an accurate measure of the static viscosity {eta} in the presence of a modest level of friction as in dusty plasma experiments.

  19. Viscosity calculated in simulations of strongly coupled dusty plasmas with gas friction a)

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Goree, J.; Liu, Bin

    2011-05-01

    A two-dimensional strongly coupled dusty plasma is modeled using Langevin and frictionless molecular dynamical simulations. The static viscosity ? and the wave-number-dependent viscosity ?(k) are calculated from the microscopic shear in the random motion of particles. A recently developed method of calculating the wave-number-dependent viscosity ?(k) is validated by comparing the results of ?(k) from the two simulations. It is also verified that the Green-Kubo relation can still yield an accurate measure of the static viscosity ? in the presence of a modest level of friction as in dusty plasma experiments.

  20. A rotating two-phase gas/liquid flow for pressure reduction in underwater plasma arc welding

    SciTech Connect

    Steinkamp, H.; Creutz, M.; Mewes, D.; Bartzsch, J. [Univ. of Hanover (Germany)

    1994-12-31

    Plasma arc welding processes are used in off-shore industry for the construction and maintenance in the wet surrounding of underwater structures and pipelines. In greater water depth the density of the plasma gas increase because of the greater hydrostatic pressure. This causes an increase of the conductive heat losses to the wet surrounding. To keep up the energy flux to the workpiece a pressure reduction is favorable against the surrounding. To keep up the energy flux to the workpiece a pressure reduction is favorable against the surrounding. The plasma arc has to burn in a locally dry area. This requirement can be fulfilled by a rotating disc placed above the workpiece. In the gap between the lower end of the cylinder and the workpiece a rotating two-phase flow is maintained. The flow around the rotating disc is experimentally investigated. The rotating disc is placed above the surface of the workpiece which is simulated by a flat plate. Water is forced out of the cylinder due to centrifugal forces set up by the rotating disc and flat plate. The velocity distribution in the flow is measured by Laser-Doppler-Anemometry. The phase distribution in the two-phase flow in the gap is measured by local electrical probes. The static pressure in the gaseous atmosphere is reduced in comparison to the hydrostatic pressure of the surrounding water. The pressure reduction is given by the void fraction, the phase distribution and the volume flow rates of both phases in the gap as well as by the speed of revolution and the design of the disc and the work surface. Apart from the investigations on the fluid dynamics, the method to reduce the pressure was technically proved. Experiments were carried out under water with a plasma MIG welder.

  1. Wafer heating mechanisms in a molecular gas, inductively coupled plasma: in situ, real time wafer surface measurements and three-dimensional thermal modeling

    SciTech Connect

    Titus, M. J.; Graves, D. B. [Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States)

    2008-09-15

    The authors report measurements and modeling of wafer heating mechanisms in an Ar/O{sub 2} inductively coupled plasma (ICP). The authors employed a commercially available on-wafer sensor system (PlasmaTemp developed by KLA-Tencor) consisting of an on-board electronics module housing battery power and data storage with 30 temperature sensors embedded onto the wafer at different radial positions. This system allows for real time, in situ wafer temperature measurements. Wafer heating mechanisms were investigated by combining temperature measurements from the PlasmaTemp sensor wafer with a three-dimensional heat transfer model of the wafer and a model of the ICP. Comparisons between pure Ar and Ar/O{sub 2} discharges demonstrated that two additional wafer heating mechanisms can be important in molecular gas plasmas compared to atomic gas discharges. The two mechanisms are heating from the gas phase and O-atom surface recombination. These mechanisms were shown to contribute as much as 60% to wafer heating under conditions of low bias power. This study demonstrated how the 'on-wafer' temperature sensor not only yields a temperature profile distribution across the wafer, but can be used to help determine plasma characteristics, such as ion flux profiles or plasma processing temperatures.

  2. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  3. Fracture and fatigue properties of acrylic bone cement: the effects of mixing method, sterilization treatment, and molecular weight.

    PubMed

    Graham, J; Pruitt, L; Ries, M; Gundiah, N

    2000-12-01

    The purpose of this study was to characterize the relative and combined effects of sterilization, molecular weight, and mixing method on the fracture and fatigue performance of acrylic bone cement. Palacos R brand bone cement powder was sterilized using ethylene oxide gas (EtO) or gamma irradiation. Nonsterile material was used as a control. Molecular weights of the bone-cement powders and cured cements were measured using gel permeation chromatography. Hand and vacuum mixing were employed to mold single edge-notched bend specimens for fracture toughness testing. Molded dog-bone specimens were used for fatigue tests. Electron microscopy was used to study fracture mechanisms. Analysis of variance and Student t-tests were used to compare fracture and fatigue performance between sterilization and mixing groups. Our results indicate that vacuum mixing improved significantly the fracture and fatigue resistance (P<.05, P<.07) over hand mixing in radiation-sterilized and EtO-sterilized groups. In vacuum-mixed cement, the degradation in molecular weight resulting from gamma irradiation decreased fracture resistance significantly when compared with EtO sterilization and control (P<.05). A corresponding decrease in fatigue resistance was observed in the cement that was degraded severely by a radiation dose of 10 MRad (P<.05). In contrast, EtO sterilization did not result in a significantly different fracture resistance when compared with unsterilized controls for vacuum-mixed cement (P>.1). For hand-mixed cement, fracture and fatigue resistance appeared to be independent of sterilization method. This independence is believed to be the result of higher porosity that compromised the mechanical properties and obscures any effect of sterilization. Our results indicate that a combination of nonionizing sterilization and vacuum mixing resulted in the best mechanical performance and is most likely to contribute to enhanced longevity in vivo. PMID:11112200

  4. Removal of ammonia from gas streams with dielectric barrier discharge plasmas

    Microsoft Academic Search

    Lanyan Xia; Li Huang; Xiaohong Shu; Renxi Zhang; Wenbo Dong; Huiqi Hou

    2008-01-01

    We reported on the experimental study of gas-phase removal of ammonia (NH3) via dielectric barrier discharge (DBD) at atmospheric pressure, in which we mainly concentrated on three aspects—influence of initial NH3 concentration, peak voltage, and gas residence time on NH3 removal efficiency. Effectiveness, e.g. the removal efficiency, specific energy density, absolute removal amount and energy yield, of the self-made DBD

  5. Microwave plasma assisted supersonic gas jet deposition of thin film materials

    DOEpatents

    Schmitt, J.J. III; Halpern, B.L.

    1993-10-26

    An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

  6. Method for microwave plasma assisted supersonic gas jet deposition of thin films

    DOEpatents

    Schmitt, J.J. III; Halpern, B.L.

    1994-10-18

    A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets. 5 figs.

  7. Method for microwave plasma assisted supersonic gas jet deposition of thin films

    DOEpatents

    Schmitt, III, Jerome J. (New Haven, CT); Halpern, Bret L. (Bethany, CT)

    1994-01-01

    A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets.

  8. Determinants for glycophospholipid anchoring of the Saccharomyces cerevisiae GAS1 protein to the plasma membrane.

    PubMed

    Nuoffer, C; Jenö, P; Conzelmann, A; Riezman, H

    1991-01-01

    A 125-kDa glycoprotein exposed on the surface of Saccharomyces cerevisiae cells belongs to a class of eucaryotic membrane proteins anchored to the lipid bilayer by covalent linkage to an inositol-containing glycophospholipid. We have cloned the gene (GAS1) encoding the 125-kDa protein (Gas1p) and found that the function of Gas1p is not essential for cell viability. The nucleotide sequence of GAS1 predicts a 60-kDa polypeptide with a cleavable N-terminal signal sequence, potential sites for N- and O-linked glycosylation, and a C-terminal hydrophobic domain. Determination of the anchor attachment site revealed that the C-terminal hydrophobic domain of Gas1p is removed during anchor addition. However, this domain is essential for addition of the glycophospholipid anchor, since a truncated form of the protein failed to become attached to the membrane. Anchor addition was also abolished by a point mutation affecting the hydrophobic character of the C-terminal sequence. We conclude that glycophospholipid anchoring of Gas1p depends on the integrity of the C-terminal hydrophobic domain that is removed during anchor attachment. PMID:1824714

  9. Determinants for glycophospholipid anchoring of the Saccharomyces cerevisiae GAS1 protein to the plasma membrane.

    PubMed Central

    Nuoffer, C; Jenö, P; Conzelmann, A; Riezman, H

    1991-01-01

    A 125-kDa glycoprotein exposed on the surface of Saccharomyces cerevisiae cells belongs to a class of eucaryotic membrane proteins anchored to the lipid bilayer by covalent linkage to an inositol-containing glycophospholipid. We have cloned the gene (GAS1) encoding the 125-kDa protein (Gas1p) and found that the function of Gas1p is not essential for cell viability. The nucleotide sequence of GAS1 predicts a 60-kDa polypeptide with a cleavable N-terminal signal sequence, potential sites for N- and O-linked glycosylation, and a C-terminal hydrophobic domain. Determination of the anchor attachment site revealed that the C-terminal hydrophobic domain of Gas1p is removed during anchor addition. However, this domain is essential for addition of the glycophospholipid anchor, since a truncated form of the protein failed to become attached to the membrane. Anchor addition was also abolished by a point mutation affecting the hydrophobic character of the C-terminal sequence. We conclude that glycophospholipid anchoring of Gas1p depends on the integrity of the C-terminal hydrophobic domain that is removed during anchor attachment. Images PMID:1824714

  10. Michigan Institute for Plasma Sci-

    E-print Network

    Shyy, Wei

    of different types of living organisms, cells and tissues and of sterilizing temperature sensitive medical activity in living tissues and organisms. This activity can be adjusted by tuning plasma properties of Direct Non-Thermal Plasma Interaction with Living Tissue Prof. Alexander Fridman Drexel University

  11. Unified gas chromatographic–mass spectrometric method for quantitating tyrosine metabolites in urine and plasma

    Microsoft Academic Search

    Albert L Shroads; George N Henderson; Jang Cheung; Margaret O James; Peter W Stacpoole

    2004-01-01

    Tyrosine and many of its catabolites play significant roles in the in the toxicity associated with acquired and congenital forms of hypertyrosinemia. We now report a specific and sensitive GC\\/MS method for the simultaneous determination of tyrosine metabolites maleylacetone (MA), fumarylacetone (FA), succinylacetone (SA), fumarate and acetoacetate in urine and plasma. Tyrosine metabolites and an internal standard, 2-oxohexanoic acid (OHA),

  12. Evaporated-gas-induced splashing model for splat formation during plasma spraying

    Microsoft Academic Search

    Chang-Jiu Li; Jing-Long Li

    2004-01-01

    The effect of surface adsorbates on splat formation during thermal spraying is examined by controlling substrate adsorption. Splats are formed on a polished flat stainless steel substrate surface by plasma spraying. The adsorption state of the substrate is controlled with different organic substances of different boiling points and different preheating temperatures. The droplet materials used are aluminum, nickel, and Al2O3.

  13. Magnetically controlled deposition of metals using gas plasma. Quarterly progress report, October--December 1996

    SciTech Connect

    NONE

    1997-03-01

    Thin layers of secondary material are plated on substrates either by plating or spraying processes. Plating operations produce large amounts of hazardous liquid waste. Spraying, while one of the less waste intensive methods, produces {open_quotes}over spray{close_quotes} which is waste that is a result of uncontrolled nature of the spray stream. In many cases the over spray produces a hazardous waste. Spray coating is a mature process with many uses. Material can be deposited utilizing spraying technology in three basic ways: {open_quotes}Flame spraying{close_quotes}, direct spraying of molten metals and/or plasma spraying. This project is directed at controlling the plasma spraying process and thereby minimizing the waste generated in that process. The proposed process will utilize a standard plasma spray gunsmith the addition of magnetic fields to focus and control the plasma. In order to keep development cost at a minimum, the project was organized in phases. The first and current phase involves developing an analytical model that will prove the concept and be used to design a prototype. Analyzing the process and using the analysis has the potential to generate significant hardware cost savings.

  14. Magnetically controlled deposition of metals using gas plasma. Quarterly progress report, July 1995--September 1995

    SciTech Connect

    NONE

    1995-12-01

    The objective of this project is to develop a method of spraying materials on a substrate in a controlled manner to eliminate waste inherent in present plating processes. The process will utilize a standard spray gun with the addition of magnetic fields to focus and control the plasma.

  15. Strong drive compression of a gas-cooled positron plasma D. B. Cassidy,1,a

    E-print Network

    Mills, Allen P.

    in the manipulation and storage of antimatter. When used in strong magnetic fields plasma heating caused proved to be extremely useful for the storage and manipulation of antimatter.2 In particular, the excellent con- finement properties of PM traps3 permit large numbers of positrons to be accumulated

  16. Inductively coupled plasma reactive ion etching of ZnO using C2F6 and NF3-based gas mixtures

    NASA Astrophysics Data System (ADS)

    Lee, Gun-Kyo; Moon, Jong-Ha; Lee, Byung-Teak

    2006-07-01

    Inductively coupled plasma reactive ion etching (ICP RIE) of ZnO film using C2F6 and NF3-based gas mixtures was investigated as a function of ICP power, bias power, pressure, and plasma chemistry. An etch rate of about 410 nm min-1 in the case of C2F6 plasma and about 380 nm min-1 in the case of NF3 plasma was obtained at the optimum condition, with vertical sidewalls and smooth surfaces, which is about 30% higher than the etch rates obtained in the previous reports on ICP RIE of ZnO using CH4 or chlorine-related gas mixtures. Basically no chamber contamination and corrosion was observed, indicating that fluorine plasmas are more suitable for ZnO dry etching than previously studied CH4 or BCl3 plasma. The addition of 40% or more CH4 to the C2F6 plasma improved the etch rate and sidewall verticality of the etched mesas, but resulted in rough surface morphology.

  17. Male sterility and fertility restoration in crops.

    PubMed

    Chen, Letian; Liu, Yao-Guang

    2014-01-01

    In plants, male sterility can be caused either by mitochondrial genes with coupled nuclear genes or by nuclear genes alone; the resulting conditions are known as cytoplasmic male sterility (CMS) and genic male sterility (GMS), respectively. CMS and GMS facilitate hybrid seed production for many crops and thus allow breeders to harness yield gains associated with hybrid vigor (heterosis). In CMS, layers of interaction between mitochondrial and nuclear genes control its male specificity, occurrence, and restoration of fertility. Environment-sensitive GMS (EGMS) mutants may involve epigenetic control by noncoding RNAs and can revert to fertility under different growth conditions, making them useful breeding materials in the hybrid seed industry. Here, we review recent research on CMS and EGMS systems in crops, summarize general models of male sterility and fertility restoration, and discuss the evolutionary significance of these reproductive systems. PMID:24313845

  18. Encapsulation process sterilizes and preserves surgical instruments

    NASA Technical Reports Server (NTRS)

    Montgomery, L. C.; Morelli, F. A.

    1964-01-01

    Ethylene oxide is blended with an organic polymer to form a sterile material for encapsulating surgical instruments. The material does not bond to metal and can be easily removed when the instruments are needed.

  19. One- and two-dimensional modeling of argon K-shell emission from gas-puff Z-pinch plasmas

    SciTech Connect

    Thornhill, J. W.; Chong, Y. K.; Apruzese, J. P.; Davis, J.; Clark, R. W.; Giuliani, J. L. Jr.; Terry, R. E.; Velikovich, A. L.; Commisso, R. J.; Whitney, K. G.; Frese, M. H.; Frese, S. D.; Levine, J. S.; Qi, N.; Sze, H.; Failor, B. H.; Banister, J. W.; Coleman, P. L.; Coverdale, C. A.; Jones, B. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Berkeley Scholars, Beltsville, Maryland 20705 (United States); NumerEx, Albuquerque, New Mexico 87106 (United States); L-3 Communications/Pulse Sciences, San Leandro, California 94577 (United States); Alameda Applied Sciences, San Leandro, California 94577 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); National Nuclear Security Administration, Washington, D.C. 20585 (United States)] (and others)

    2007-06-15

    In this paper, a theoretical model is described and demonstrated that serves as a useful tool for understanding K-shell radiating Z-pinch plasma behavior. Such understanding requires a self-consistent solution to the complete nonlocal thermodynamic equilibrium kinetics and radiation transport in order to realistically model opacity effects and the high-temperature state of the plasma. For this purpose, we have incorporated into the MACH2 two-dimensional magnetohydrodynamic (MHD) code [R. E. Peterkin et al., J. Comput. Phys. 140, 148 (1998)] an equation of state, called the tabular collisional radiative equilibrium (TCRE) model [J. W. Thornhill et al., Phys. Plasmas 8, 3480 (2001)], that provides reasonable approximations to the plasma's opacity state. MACH2 with TCRE is applied toward analyzing the multidimensional implosion behavior that occurred in Decade Quad (DQ) [D. Price et al., Proceedings of the 12th IEEE Pulsed Power Conference, Monterey, CA, edited by C. Stallings and H. Kirbie (IEEE, New York, 1999), p. 489] argon gas puff experiments that employed a 12 cm diameter nozzle with and without a central gas jet on axis. Typical peak drive currents and implosion times in these experiments were {approx}6 MA and {approx}230 ns. By using Planar Laser Induced Fluorescence measured initial density profiles as input to the calculations, the effect these profiles have on the ability of the pinch to efficiently produce K-shell emission can be analyzed with this combined radiation-MHD model. The calculated results are in agreement with the experimental result that the DQ central-jet configuration is superior to the no-central-jet experiment in terms of producing more K-shell emission. These theoretical results support the contention that the improved operation of the central-jet nozzle is due to the better suppression of instabilities and the higher-density K-shell radiating conditions that the central-jet configuration promotes. When we applied the model toward projecting argon K-shell yield behavior for Sandia National Laboratories' ZR machine ({approx}25 MA peak drive currents, {approx}100 ns implosion times) [D. McDaniel et al., Proceedings of the 5th International Conference on Dense Z-Pinches, Albuquerque, NM, 2002, edited by J. Davis, C. Deeney, and N. R. Pereira (American Institute of Physics, New York, 2002), Vol. 651, p. 23] for experiments that utilize the 12 cm diameter central-jet nozzle configuration, it predicts over 1 MJ of K-shell emission is attainable.

  20. Simulation Based on Ion-Ion Plasma Techniques of Electric propulsion In Mars Mission Using Chlorine Gas

    NASA Astrophysics Data System (ADS)

    Sathiyavel, C.

    Abstract:The recently(Nov-5/2013) launched Mangalyan by the Indian space Research Organization (ISRO) to Mars orbit with Mankalyan contained by small liquid engine(MMH+N2O4).This will take long time to reach the Mars orbit that is around the 9 Months. Bi-Propellant rocket system has good thrust but low specific impulse and velocity. In future we need a rocket with good high specific impulse and high velocity of rocket system, to reduce the trip time to Mars. Electric propulsion rocket system is expected to become popular with the development of ion-ion pair techniques because this needs low propellant, Design thrust range is 1.5 N with high efficiency. An ion - ion pair of Electric propulsion rocket system is proposed in this work. Ion-Ion(positive ion- negative ion) Based Rocket system consists of three parts 1.The negative ionization stage with electro negative propellant 2. Ion-Ion plasma formation and ion accelerator 3. Exhaust of Nozzle. The Negative ions from electro negative gas are produced by adding up the gas, such as chlorine with electron emitted from an Electron gun ionization chamber. The formulate of large stable negative ion is achievable in chlorine gas with respect to electron affinity (?E). When a neutral chlorine atom in the gaseous form picks up an electron to form a Cl- ion, it releases energy of 3.6eV. The negative ion density becomes several orders of magnitude larger than that of the electrons, hence forming ion-ion (positive ion - negative ion) plasma at the periphery of the discharge. The distance between ion- ions is important for the evaluate the rocket thrust and it also that the distance is determined by the exhaust velocity of the propellant. Accelerate the ion-ion plasma to a high velocity in the thrust vector direction via electron gun and the exhaust of ions through Nozzle. The simulation of the ion propulsion system has been carried out by MATLAB. By comparing the simulation results with the theoretical and previous results, we found that the proposed method is achieved of thrust value with high efficiency for simulating the ion propulsion rocket system.

  1. Improved plasma accelerator

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  2. Transfer of Ogu cytoplasmic male sterility to Brassica juncea and improvement of the male sterile line through somatic cell fusion

    Microsoft Academic Search

    P. B. Kirti; S. S. Banga; S. Prakash; V. L. Chopra

    1995-01-01

    Male sterility conferred by ogu cytoplasm of Raphanus sativus has been transferred to Brassica juncea cv ‘RLM 198’ from male-sterile B. napus through repeated backcrossing and selection. The male-sterile B. juncea is, however, highly chlorotic and late. It has low female (seed) fertility and small contorted pods. To rectify these defects, protoplasts of the male sterile were fused with normal

  3. Effect of N2 and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes

    NASA Astrophysics Data System (ADS)

    Zhirkov, Igor; Oks, Efim; Rosen, Johanna

    2015-06-01

    DC arc plasma from Ti, Al, and Ti1-xAlx (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N2 pressures in the range 10-6 to 3 × 10-2 Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. Introducing N2 above ˜5 × 10-3 Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N2 atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.

  4. Is cosmology compatible with sterile neutrinos?

    SciTech Connect

    Dodelson, Scott; /Fermilab; Melchiorri, Alessandro; /Rome U. /INFN, Rome; Slosar, Anze; /Ljubljana U.

    2005-11-01

    By combining data from cosmic microwave background (CMB) experiments (including the recent BOOMERANG-2K2 results), large scale structure (LSS) and Lyman-{alpha} forest observations, we constrain the hypothesis of a fourth, sterile, massive neutrino. For the 3 massless + 1 massive neutrino case we bound the mass of the sterile neutrino to m{sub s} < 0.55eV at 95% c.l.. These results exclude at high significance the sterile neutrino hypothesis as an explanation of the LSND anomaly. We then generalize the analysis to account for active neutrino masses (which tightens the limit to m{sub s} < 0.51eV) and the possibility that the sterile abundance is not thermal. In the latter case, the constraints in the (mass, density) plane are non-trivial. For a mass of > 1eV or < 0.05eV the cosmological energy density in sterile neutrinos is always constrained to be {omega}{sub {nu}} < 0.005 at 95% c.l.. However, for a sterile neutrino mass of {approx} 0.25 eV, {omega}{sub {nu}} can be as large as 0.015.

  5. Plasma-Mediated Inactivation of Pseudomonas aeruginosa Biofilms Grown on Borosilicate Surfaces under Continuous Culture System

    PubMed Central

    Vandervoort, Kurt G.; Brelles-Mariño, Graciela

    2014-01-01

    Biofilms are microbial communities attached to a surface and embedded in a matrix composed of exopolysaccharides and excreted nucleic acids. Bacterial biofilms are responsible for undesirable effects such as disease, prostheses colonization, biofouling, equipment damage, and pipe plugging. Biofilms are also more resilient than free-living cells to regular sterilization methods and therefore it is indispensable to develop better ways to control and remove them. The use of gas discharge plasmas is a good alternative since plasmas contain a mixture of reactive agents well-known for their decontamination potential against free microorganisms. We have previously reported that Pseudomonas aeruginosa biofilms were inactivated after a 1-min plasma exposure. We determined that the adhesiveness and the thickness of Pseudomonas biofilms grown on borosilicate were reduced. We also reported sequential morphological changes and loss of viability upon plasma treatment. However, the studies were carried out in batch cultures. The use of a continuous culture results in a more homogenous environment ensuring reproducible biofilm growth. The aim of this work was to study plasma-mediated inactivation of P. aeruginosa biofilms grown on borosilicate in a continuous culture system. In this paper we show that biofilms grown on glass under continuous culture can be inactivated by using gas discharge plasma. Both biofilm architecture and cell culturabilty are impacted by the plasma treatment. The inactivation kinetics is similar to previously described ones and cells go through sequential changes ranging from minimal modification without loss of viability at short plasma exposure times, to major structure and viability loss at longer exposure times. We report that changes in biofilm structure leading to the loss of culturability and viability are related to a decrease of the biofilm matrix adhesiveness. To our knowledge, there has been no attempt to evaluate the inactivation/sterilization of biofilms grown in a continuous system. PMID:25302815

  6. Plasma-mediated inactivation of Pseudomonas aeruginosa biofilms grown on borosilicate surfaces under continuous culture system.

    PubMed

    Vandervoort, Kurt G; Brelles-Mariño, Graciela

    2014-01-01

    Biofilms are microbial communities attached to a surface and embedded in a matrix composed of exopolysaccharides and excreted nucleic acids. Bacterial biofilms are responsible for undesirable effects such as disease, prostheses colonization, biofouling, equipment damage, and pipe plugging. Biofilms are also more resilient than free-living cells to regular sterilization methods and therefore it is indispensable to develop better ways to control and remove them. The use of gas discharge plasmas is a good alternative since plasmas contain a mixture of reactive agents well-known for their decontamination potential against free microorganisms. We have previously reported that Pseudomonas aeruginosa biofilms were inactivated after a 1-min plasma exposure. We determined that the adhesiveness and the thickness of Pseudomonas biofilms grown on borosilicate were reduced. We also reported sequential morphological changes and loss of viability upon plasma treatment. However, the studies were carried out in batch cultures. The use of a continuous culture results in a more homogenous environment ensuring reproducible biofilm growth. The aim of this work was to study plasma-mediated inactivation of P. aeruginosa biofilms grown on borosilicate in a continuous culture system. In this paper we show that biofilms grown on glass under continuous culture can be inactivated by using gas discharge plasma. Both biofilm architecture and cell culturability are impacted by the plasma treatment. The inactivation kinetics is similar to previously described ones and cells go through sequential changes ranging from minimal modification without loss of viability at short plasma exposure times, to major structure and viability loss at longer exposure times. We report that changes in biofilm structure leading to the loss of culturability and viability are related to a decrease of the biofilm matrix adhesiveness. To our knowledge, there has been no attempt to evaluate the inactivation/sterilization of biofilms grown in a continuous system. PMID:25302815

  7. Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

    NASA Technical Reports Server (NTRS)

    Sumner, I. E.; Ruckle, D. L.

    1980-01-01

    As part of a NASA program to reduce fuel consumption of current commercial aircraft engines, methods were investigated for improving the durability of plasma sprayed ceramic coatings for use on vane platforms in the JT9D turbofan engine. Increased durability concepts under evaluation include use of improved strain tolerant microstructures and control of the substrate temperature during coating application. Initial burner rig tests conducted at temperatures of 1010 C (1850 F) indicate that improvements in cyclic life greater than 20:1 over previous ceramic coating systems were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 100-cycle JT9D engine endurance test with only minor damage occurring to the coatings.

  8. Low stimulated Brillouin backscatter observed from large, hot plasmas in gas-filled Hohlraums

    SciTech Connect

    Powers, L.V.; Turner, R.E.; Kauffman, R.L.; Berger, R.L.; Amendt, P.; Back, C.A.; Bernat, T.P.; Dixit, S.N.; Eimerl, D.; Harte, J.A.; Henesian, M.A.; Kalantar, D.H.; Lasinski, B.F.; MacGowan, B.J.; Montgomery, D.S.; Munro, D.H.; Pennington, D.M.; Shepard, T.D.; Stone, G.F.; Suter, L.J.; Williams, E.A. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    1995-04-10

    Stimulated Brillouin scattering (SBS) has been measured from hohlraums with plasma conditions similar to those predicted for high gain targets. The plasmas differ from the more familiar exploding foil or solid targets in being hot (3 keV), high electron density (10{sup 21} cm{sup --3}), stationary, confined within a gold cylinder, and uniform over greater than 2 mm. Peak SBS backscatter is {lt}3% in these hohlraums for an interaction beam with intensities of (1{minus}4){times}10{sup 15} W/cm{sup 2}, laser wavelength equal to 0.351 {mu}m, {ital f}/4 or {ital f}/8 focusing optics, and a variety of beam smoothing implementations.

  9. Gas-to-liquids process using multi-phase flow, non-thermal plasma microreactor

    Microsoft Academic Search

    An?l A??ral; Tomohiro Nozaki; Masahiko Nakase; Shuhei Yuzawa; Ken Okazaki

    2011-01-01

    A multi-phase flow non-thermal plasma microreactor based on dielectric barrier discharge has been developed for partial oxidation of methane to liquid oxygenates at atmospheric pressure. A pulsed water injection method has been used to remove condensable liquid components from the active discharge region. The effect of the pulsed water injection on methane conversion, yield of oxygenates and hydrogen peroxide (H2O2)

  10. Magnetically controlled deposition of metals using gas plasma. Quarterly progress report, July--September 1996

    SciTech Connect

    Woodall, D.M.; Lemmon, E.C.

    1996-11-01

    Objective is to develop a method of spraying materials on a substrate in a controlled manner to eliminate the waste inherent in present plating processes. The process under investigation is magnetically controlled plasma spraying. The field equations have been cast in a format that allows finite element solution. Potential flow and finite element solutions for temperature isolines and velocity vectors are compared for 2-D flow with heat addition.

  11. Aluminum nitride-silicon carbide solid solutions grown by plasma-assisted, gas-source molecular beam epitaxy

    SciTech Connect

    Kern, R.S.; Rowland, L.B.; Tanaka, S.; Davis, R.F. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, North Carolina 27695-7907 (United States)

    1998-07-01

    Solid solutions of aluminum nitride (AlN) and silicon carbide (SiC) have been grown at 900{endash}1300thinsp{degree}C on vicinal {alpha}(6H)-SiC(0001) substrates by plasma-assisted, gas-source molecular beam epitaxy. Under specific processing conditions, films of (AlN){sub x}(SiC){sub 1{minus}x} with 0.2{le}x{le}0.8, as determined by Auger electron spectrometry (AES), were deposited. Reflection high-energy electron diffraction (RHEED) was used to determine the crystalline quality, surface character, and epilayer polytype. Analysis of the resulting surfaces was also performed by scanning electron microscopy (SEM). High-resolution transmission electron microscopy (HRTEM) revealed that monocrystalline films with x{ge}0.25 had the wurtzite (2H) crystal structure; however, films with x{lt}0.25 had the zincblende (3C) crystal structure. {copyright} {ital 1998 Materials Research Society.}

  12. A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments.

    PubMed

    Loebner, Keith T K; Underwood, Thomas C; Cappelli, Mark A

    2015-06-01

    A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated. PMID:26133835

  13. A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments

    NASA Astrophysics Data System (ADS)

    Loebner, Keith T. K.; Underwood, Thomas C.; Cappelli, Mark A.

    2015-06-01

    A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated.

  14. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    NASA Astrophysics Data System (ADS)

    Malinina, A. A.; Malinin, A. N.

    2013-12-01

    Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10-14 m3/s for a reduced electric field of E/ N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (?max = 502 nm) was observed in this experiment.

  15. Improved plasma sprayed MCrAlY coatings for aircraft gas turbine applications

    NASA Technical Reports Server (NTRS)

    Pennisi, F. J.; Gupta, D. K.

    1981-01-01

    Eighteen plasma sprayed coating systems, nine based on the NiCoCrAlY chemistry and nine based on the CoCrAlY composition, were evaluated to identify coating systems which will provide equivalent or superior life to that shown by the electron beam physical vapor deposited NiCoCrAlY and CoCrAlY coatings respectively. NiCoCrAlY-type coatings were examined on a single crystal alloy and the CoCrAlY based coatings were optimized on the B1900 + Hf alloy. Cyclic burner rig oxidation and hot corrosion and tensile ductility tests were used to evaluate the various coating candidates. For the single crystal alloy, a low pressure chamber plasma sprayed NiCoCrAlY + Si coating exhibited a 2X oxidation life improvement at 1121 C (2050 F) over the vapor deposited NiCoCrAlY material while showing equivalent tensile ductility. A silicon modified low pressure chamber plasma sprayed CoCrAlY coating was found to be more durable than the baseline vapor deposited CoCrAlY coating on the B1900 + Hf alloy.

  16. Development of laser induced fluorescence diagnostic for measuring the parameters of plasma containing rare gas species

    SciTech Connect

    Gorbunov, A. V.; Molodtsov, N. A.; Moskalenko, I. V.; Shcheglov, D. A. [Russian Research Center, ''Kurchatov Institute'', Moscow 123182 (Russian Federation)

    2010-10-15

    Laser induced fluorescence (LIF) technique development activity for measurement of plasma parameters in ITER divertor plasma is described. Helium density is the task of priority, but Doppler measurement of ion (atom) temperatures is also the aim of the program. The concept of ITER scenarios includes injection of ''extrinsic'' impurities (Ne, Ar, and Kr). It is possible to use the species as tracing elements for measurement of T{sub i}, T{sub a}. The program included modeling experiments on PNX-U (a multicusp trap with microwave argon plasma). Helium was added by puffing into discharge. Temperatures T{sub i}(Ar{sup 1+}) and T{sub a}(He{sup 0}) have been measured by scanning laser line across absorption line of species. Summarizing of fluorescence signals provided input data for estimation of Ar{sup 1+} and He{sup 0} densities via interpretative collisional-radiative models. Besides, the collisional-radiative model has been used for estimation of electron density using the ratio of fluorescence signals at 388.9 and 706.5 nm helium lines.

  17. Effect of N-containing additive gases on global warming gas emission during remote plasma cleaning process of silicon nitride PECVD chamber using C 4F 8\\/O 2\\/Ar chemistry

    Microsoft Academic Search

    C. H. Oh; N.-E. Lee; J. H. Kim; G. Y. Yeom; S. S. Yoon; T. K. Kwon

    2002-01-01

    In this study, remote plasma cleaning process was investigated in a silicon nitride plasma enhanced chemical vapor deposition chamber using C4F8\\/O2\\/Ar and C4F8\\/O2\\/Ar+additive gas. The remote plasma source used in the present experiments showed the capability of nearly complete destruction, destruction removal efficiency ?100%, of C4F8 gas with or without the additive N2, N2O and NO gases. The cleaning rate

  18. [Determination of triazolam and midazolam in human plasma using gas chromatography with microelectron capture detection for clinical application].

    PubMed

    Tsutsumi, Kimiko; Iwao, Miyuki; Kotegawa, Tsutomu; Imai, Hiromitsu; Ohashi, Kyoichi; Nakano, Shigeyuki

    2014-01-01

    A method for the simple and reliable determination of triazolam and midazolam in human plasma using gas chromatography with microelectron capture detection has been developed. Samples (0.5 mL of plasma) were prepared using a simple solvent extraction with 3% isoamyl alcohol/benzene in the presence of NaOH. Two microlitres of the extract were injected onto the capillary column ((5%-phenyl)-methylpolysiloxane). The method was found to be valid in terms of selectivity, linearity, precision, accuracy, and recovery over the concentration range of 0.2 to 20 ng/mL for triazolam, and from 0.5 to 200 ng/mL for midazolam, respectively. Intra- and inter-day precisions determined at three concentrations were from 4.1 to 9.3% for triazolam and from 2.9 to 13.0% for midazolam. The accuracies were within 17.7% for triazolam and within 13.0% for midazolam. This proposed method was successfully applied to a pharmacokinetic study of triazolam or midazolam in healthy volunteers. PMID:24389624

  19. A review of the gas species activity and control of pulsed plasma technology during the nitriding, carburizing and carbonitriding processes

    SciTech Connect

    Pye, D. [SECO/WARWICK Corp., Meadville, PA (United States)

    1995-12-31

    The control of gas activity and process technology has developed tremendously over the past two decades. While once considered to be primitive control systems using simple PID loops with thermocouples that were suspect and unable to perform repeatedly and consistently during the arduous process of plasma nitriding and processing, developments in recent years have elevated the control of the process into what might be considered one of the most controllable processes of the latter part of this century. The advent of plasma processing technology has improved control methods by observing and harnessing each of the various process parameters into many different combinations of control systems. Some of these control systems can control the complete function of the process, thus freeing the operator entirely for other duties, except that of load and unload, to the point where the operator is intimately involved with the process. Some of the control methods report from the process to a PLC through to a PC, and current developments rely entirely on computers and developed software shown on various screens. This presentation will review some of the more common process control methods, including that of highly developed PC systems.

  20. Simultaneous removal of nitrogen oxide/nitrogen dioxide/sulfur dioxide from gas streams by combined plasma scrubbing technology.

    PubMed

    Chang, Moo Been; Lee, How Ming; Wu, Feeling; Lai, Chi Ren

    2004-08-01

    Oxides of nitrogen (NOx) [nitrogen oxide (NO) + nitrogen dioxide (NO2)] and sulfur dioxide (SO2) are removed individually in traditional air pollution control technologies. This study proposes a combined plasma scrubbing (CPS) system for simultaneous removal of SO2 and NOx. CPS consists of a dielectric barrier discharge (DBD) and wet scrubbing in series. DBD is used to generate nonthermal plasmas for converting NO to NO2. The water-soluble NO2 then can be removed by wet scrubbing accompanied with SO2 removal. In this work, CPS was tested with simulated exhausts in the laboratory and with diesel-generator exhausts in the field. Experimental results indicate that DBD is very efficient in converting NO to NO2. More than 90% removal of NO, NOx, and SO2 can be simultaneously achieved with CPS. Both sodium sulfide (Na2S) and sodium sulfite (Na2SO3) scrubbing solutions are good for NO2 and SO2 absorption. Energy efficiencies for NOx and SO2 removal are 17 and 18 g/kWh, respectively. The technical feasibility of CPS for simultaneous removal of NO, NO2, and SO2 from gas streams is successfully demonstrated in this study. However, production of carbon monoxide as a side-product (approximately 100 ppm) is found and should be considered. PMID:15373362