Note: This page contains sample records for the topic gas plasma sterilization from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Gas plasma sterilization of microorganisms and mechanisms of action  

PubMed Central

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.

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

2010-01-01

2

Space hardware compatibility tests with hydrogen peroxide gas plasma sterilization  

NASA Astrophysics Data System (ADS)

The exploration of the Solar System shall comply with planetary protection requirements handled presently by the Committee of Space Research (COSPAR). The goal of planetary protection is to protect celestial bodies from terrestrial contamination and also to protect the Earth environment from an eventual contamination carried by return samples or by space systems. For project teams, avoiding the biological contamination of other Solar System bodies such as Mars imposes to perform unusual tasks at technical and operational constraints point of view. The main are the reduction of bioburden on space hardware, the sterile integration of landers, the control of the biological cleanliness and the limitation of crash probability. In order to reduce the bioburden on spacecraft, the use of qualified sterilization processes may be envisaged. Since 1992 now, with the Mars96 mission, one of the most often used is the Sterrad(R) process working with hydrogen peroxide gas plasma. In the view of future Mars exploration programs, after tests performed in the frame of previous missions, a new test campaign has been performed on thermal coatings and miscellaneous materials coming from an experiment in order to assess the compatibility of space hardware and material with this sterilization process.

Faye, Delphine; Aguila, Alexandre; Debus, Andre; Remaury, Stephanie; Nabarra, Pascale; Darbord, Jacques C.; Soufflet, Caroline; Destrez, Philippe; Coll, Patrice; Coscia, David

3

Assessment of the efficacy of a low temperature hydrogen peroxide gas plasma sterilization system  

Microsoft Academic Search

The STERRAD 100 sterilization system (Johnson & Johnson Medical Ltd) uses low temperature hydrogen peroxide gas plasma for sterilization of heat labile equipment. The efficacy of the machine was tested by contaminating a standard set of instruments with different organisms and using a filtration method to assess recovery of organisms from the wash fluids of instruments post-sterilization. Experiments were performed

M. S. Kyi; J. Holton; G. L. Ridgway

1995-01-01

4

Assessment of the efficacy of a low temperature hydrogen peroxide gas plasma sterilization system.  

PubMed

The STERRAD 100 sterilization system (Johnson & Johnson Medical Ltd) uses low temperature hydrogen peroxide gas plasma for sterilization of heat labile equipment. The efficacy of the machine was tested by contaminating a standard set of instruments with different organisms and using a filtration method to assess recovery of organisms from the wash fluids of instruments post-sterilization. Experiments were performed under clean (the organism only) and dirty (organism mixed with egg protein) conditions. A parallel study conducted using a 3M STERIVAC ethylene oxide sterilizer could not be completed owing to closure of the ethylene oxide plant. For sterilization of instruments with long and narrow lumens, hydrogen peroxide adaptors are necessary. The STERRAD 100 sterilizer can achieve effective sterilization of heat labile instruments with a reduction of 6 log10 cfu/mL of organisms tested. This method has the advantages over ethylene oxide sterilization of safety, ease of maintenance and no requirement for aeration time. PMID:8926377

Kyi, M S; Holton, J; Ridgway, G L

1995-12-01

5

Sterilization of Bacillus subtilis Spores Using an Atmospheric Plasma Jet with Argon and Oxygen Mixture Gas  

NASA Astrophysics Data System (ADS)

To determine an efficient sterilization mechanism, Bacillus subtilis spore samples were exposed to an atmospheric plasma jet. By using argon/oxygen mixture gas, the decimal reduction value was reduced from 60 s (using argon gas) to 10 s. More dramatically, after 5 min treatment, the colony-forming unit (CFU) was reduced by six orders. To understand the underlying mechanism of the efficient sterilization by plasma, the contributions from heat, UV radiation, charged particles, ozone, and reactive oxygen radicals were distinguished in this work, showing that charged particles and ozone were the main killing factors. The shape changes of the spores were also discussed.

Shen, Jie; Cheng, Cheng; Fang, Shidong; Xie, Hongbing; Lan, Yan; Ni, Guohua; Meng, Yuedong; Luo, Jiarong; Wang, Xiangke

2012-03-01

6

Effect of gas composition on spore mortality and etching during low-pressure plasma sterilization.  

PubMed

The aim of this work was to investigate possible mechanisms of sterilization by low-temperature gas plasma: spore destruction by plasma is compared with etching of synthetic polymers. Bacillus subtilis spores were inoculated at the bottom of glass vials and subjected to different plasma gas compositions (O(2), O(2)/Ar, O(2)/H(2), CO(2), and O(2)/CF(4)), all known to etch polymers. O(2)/CF(4) plasma exhibited much higher efficacy than all other gases or gas mixtures tested, with a more than 5 log decrease in 7.5 min, compared with a 2 log decrease with pure oxygen. Examination by scanning electron microscopy showed that spores were significantly etched after 30 min of plasma exposure, but not completely. We speculate about their etch resistance compared with that of synthetic polymers on the basis of their morphology and complex coating structure. In contrast to so-called in-house plasma, sterilization by Sterrad(R) tended to increase the observed spores' size; chemical modification (oxidation), rather than etching, is believed to be the sterilization mechanism of Sterrad(R). PMID:10813754

Lerouge, S; Wertheimer, M R; Marchand, R; Tabrizian, M; Yahia, L

2000-07-01

7

Sterilization mechanism of nitrogen gas plasma: induction of secondary structural change in protein.  

PubMed

The mechanism of action on biomolecules of N? gas plasma, a novel sterilization technique, remains unclear. Here, the effect of N? gas plasma on protein structure was investigated. BSA, which was used as the model protein, was exposed to N? gas plasma generated by short-time high voltage pulses from a static induction thyristor power supply. N? gas plasma-treated BSA at 1.5?kilo pulses per second showed evidence of degradation and modification when assessed by Coomassie brilliant blue staining and ultraviolet spectroscopy at 280?nm. Fourier transform infrared spectroscopy analysis was used to determine the protein's secondary structure. When the amide I region was analyzed in the infrared spectra according to curve fitting and Fourier self-deconvolution, N? gas plasma-treated BSA showed increased ?-helix and decreased ?-turn content. Because heating decreased ?-helix and increased ?-sheet content, the structural changes induced by N? gas plasma-treatment of BSA were not caused by high temperatures. Thus, the present results suggest that conformational changes induced by N? gas plasma are mediated by mechanisms distinct from heat denaturation. PMID:23617321

Sakudo, Akikazu; Higa, Masato; Maeda, Kojiro; Shimizu, Naohiro; Imanishi, Yuichiro; Shintani, Hideharu

2013-07-01

8

Experimental study on a new sterilization process using plasma source ion implantation with N2 gas  

NASA Astrophysics Data System (ADS)

Plasma source ion implantation (PSII) with negative high voltage pulses has been applied to the sterilization process as a technique suitable for sterilization of three-dimensional work pieces. Pulsed high negative voltage (0-10 ?s pulse width, 900 pulses/s, -9 to -16 kV) was applied to the electrode in this process at a gas pressure of 2-7 Pa of N2. This process has been found to be capable of generating glow discharge plasma around a stainless electrode, on which quartz glass samples with biological materials are placed. We found that the PSII process reduced the numbers of active Bacillus pumilus cells using N2 gas plasma generated by pulsed dc voltages. The number of bacteria survivors was reduced by 105×with 5-10 min exposure. The state of cells on quartz glass was observed by scanning electron microscopy with and without exposure. We found that the ion energy is the most important processing parameter. The technique is demonstrated to be an effective means of low-temperature surface sterilization, with very little damage to the target.

Yoshida, M.; Tanaka, T.; Watanabe, S.; Takagi, T.; Shinohara, M.; Fujii, S.

2003-07-01

9

Inactivation of animal and human prions by hydrogen peroxide gas plasma sterilization.  

PubMed

Prions cause various transmissible spongiform encephalopathies. They are highly resistant to the chemical and physical decontamination and sterilization procedures routinely used in healthcare facilities. The decontamination procedures recommended for the inactivation of prions are often incompatible with the materials used in medical devices. In this study, we evaluated the use of low-temperature hydrogen peroxide gas plasma sterilization systems and other instrument-processing procedures for inactivating human and animal prions. We provide new data concerning the efficacy of hydrogen peroxide against prions from in vitro or in vivo tests, focusing on the following: the efficiency of hydrogen peroxide sterilization and possible interactions with enzymatic or alkaline detergents, differences in the efficiency of this treatment against different prion strains, and the influence of contaminating lipids. We found that gaseous hydrogen peroxide decreased the infectivity of prions and/or the level of the protease-resistant form of the prion protein on different surface materials. However, the efficiency of this treatment depended strongly on the concentration of hydrogen peroxide and the delivery system used in medical devices, because these effects were more pronounced for the new generation of Sterrad technology. The Sterrad NX sterilizer is 100% efficient (0% transmission and no protease-resistant form of the prion protein signal detected on the surface of the material for the mouse-adapted bovine spongiform encephalopathy 6PB1 strain and a variant Creutzfeldt-Jakob disease strain). Thus, gaseous or vaporized hydrogen peroxide efficiently inactivates prions on the surfaces of medical devices. PMID:19563265

Rogez-Kreuz, C; Yousfi, R; Soufflet, C; Quadrio, I; Yan, Z-X; Huyot, V; Aubenque, C; Destrez, P; Roth, K; Roberts, C; Favero, M; Clayette, P

2009-08-01

10

Inactivation of duck hepatitis B virus by a hydrogen peroxide gas plasma sterilization system: laboratory and 'in use' testing.  

PubMed

Human hepatitis B virus (HBV) is an important cause of nosocomial infections and can be transmitted by contaminated instruments. However, tests of the efficacy of sterilization of materials and equipment contaminated by HBV are difficult to perform because the virus cannot be cultured in the laboratory. In this study, we aimed to evaluate the capability of a low temperature, hydrogen peroxide gas plasma sterilizer (Sterrad, Advanced Sterilization Products, Irvine California,) to inactivate duck hepatitis B virus (DHBV). In laboratory efficacy studies using DHBV dried on to glass filter carriers and exposed to one-half of the hydrogen peroxide gas plasma sterilization process, there was a 10(7) or greater decrease in the viral titer, with no infectivity detected on the carriers after treatment. In-use studies were performed using a laparoscope that was experimentally contaminated with DHBV to mimic the possible transmission of infection between successive patients. Following exposure to the hydrogen peroxide gas plasma sterilization process no transmission of DHBV infection from the laparoscope occurred despite obvious visual soiling with blood (N = 8) while the transmission rate for the unprocessed laparoscope (positive control) was 100% (26/26), and that for instruments after a water wash was 63% (7/11). In conclusion the hydrogen gas plasma sterilization process completely inactivates DHBV a representative of the hepadna group of viruses. PMID:10392338

Vickery, K; Deva, A K; Zou, J; Kumaradeva, P; Bissett, L; Cossart, Y E

1999-04-01

11

Comparison of low-temperature hydrogen peroxide gas plasma sterilization for endoscopes using various Sterrad models.  

PubMed

This study compared the effectiveness of sterilizing four types of endoscope using different models of the Sterrad system (Sterrad 50, 100, 100S and 200). Sterilization levels meeting international requirements were attained in all cases with carriers inoculated with Geobacillus stearothermophilus spores. The endoscopes were tested in half cycles ('overkill'). This is the first study to compare the Sterrad models marketed to date in terms of effective sterilization of endoscopes with narrow lumens. PMID:15749314

Okpara-Hofmann, J; Knoll, M; Dürr, M; Schmitt, B; Borneff-Lipp, M

2005-04-01

12

Comparison of the effects of gamma radiation and low temperature hydrogen peroxide gas plasma sterilization on the molecular structure, fatigue resistance, and wear behavior of UHMWPE.  

PubMed

The effects of gamma radiation and low temperature hydrogen peroxide gas plasma (HPGP) sterilization on structure and cyclic mechanical properties were examined for orthopedic grade ultra-high-molecular-weight polyethylene (UHMWPE) and compared to each other as well as to no sterilization (control). Density was monitored with a density gradient column and was found to be directly influenced by the sterilization method employed: Gamma radiation led to an increase, while plasma did not. Oxidation of the polymer was studied by observing changes in the carbonyl peak with Fourier transform infrared spectrometry and was found to be strongly affected by both gamma radiation and subsequent aging, while plasma sterilization had little effect. Gamma radiation resulted in embrittlement of the polymer and a decreased resistance to fatigue crack propagation. This mechanical degradation was a direct consequence of postradiation oxidation and molecular evolution of the polymer and was not observed in the plasma-sterilized polymer. Both gamma radiation and plasma sterilization led to improved wear performance of the UHMWPE compared to the nonsterile control material. PMID:9570068

Goldman, M; Pruitt, L

1998-06-01

13

Plasma Sterilization Experiments.  

National Technical Information Service (NTIS)

The purpose of this project was to investigate the feasibility of antibacterial plasma treatment of biological tissue. A low- temperature plasma was produced in air that killed 1E5-1E6 bacterial populations on synthetic skin in under 20 seconds. The bacte...

D. Blessing M. Moore R. Moore

2008-01-01

14

Sterilization effects of atmospheric cold plasma brush  

NASA Astrophysics Data System (ADS)

This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0×104-1.0×105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar+O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy.

Yu, Q. S.; Huang, C.; Hsieh, F.-H.; Huff, H.; Duan, Yixiang

2006-01-01

15

Sterilization effects of atmospheric cold plasma brush  

SciTech Connect

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

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

2006-01-02

16

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

Microsoft Academic Search

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

Ozlem Yardimci; Peter Setlow

2010-01-01

17

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

Microsoft Academic Search

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

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

2003-01-01

18

Generation of a nonequlibrium plasma in heterophase atmospheric-pressure gas-liquid media and demonstration of its sterilization ability  

SciTech Connect

Results are presented from experiments on the generation of a low-temperature nonequilibrium plasma in atmospheric-pressure heterophase gas-liquid media of different compositions: (i) a liquid with air bubbles and (ii) air with liquid aerosol. To illustrate possible application of a low-temperature plasma in a heterophase medium, experiments on the inactivation of some microorganisms by a low-temperature plasma have been performed.

Akishev, Yu. S.; Grushin, M. E.; Karal'nik, V. B.; Monich, A. E.; Pan'kin, M. V.; Trushkin, N. I. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Kholodenko, V. P.; Chugunov, V. A.; Zhirkova, N. A.; Irkhina, I. A.; Kobzev, E. N. [State Research Center for Applied Microbiology (Russian Federation)

2006-12-15

19

Sterilization of Cotton Fabrics Using Plasma Treatment  

NASA Astrophysics Data System (ADS)

Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculated cotton fabrics were investigated. Oxygen plasma treatment completely sterilized the cotton fabrics inoculated with various concentrations of staphylococcus aureus. Also, the influence of plasma treatment on physical properties of fabrics was examined. It was found that the plasma treatment did not affect ultimate tensile strength and surface morphology of the fabrics because it took advantage of relatively low plasma temperature.

Shahidi, S.; Ghoranneviss, M.

2013-10-01

20

Sterilization effects of atmospheric cold plasma brush  

Microsoft Academic Search

This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0×104-1.0×105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and\\/or Ar+O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma

Q. S. Yu; C. Huang; F.-H. Hsieh; H. Huff; Yixiang Duan

2006-01-01

21

Low-pressure microwave plasma sterilization of polyethylene terephthalate bottles.  

PubMed

A low-pressure microwave plasma reactor was developed for sterilization of polyethylene terephthalate (PET) bottles. In contrast to the established method using aseptic filling machines based on toxic sterilants, here a microwave plasma is ignited inside a bottle by using a gas mixture of nitrogen, oxygen, and hydrogen. To that effect, a reactor setup was developed based on a Plasmaline antenna allowing for plasma ignition inside three-dimensional packages. A treatment time below 5 s is provided for a reduction of 10(5) and 10(4) CFU of Bacillus atrophaeus and Aspergillus niger, respectively, verified by means of a count reduction test. The sterilization results obtained by means of this challenge test are in accordance with requirements for aseptic packaging machines as defined by the U.S. Food and Drug Administration and the German Engineering Federation. The plasma sterilization process developed here for aseptic filling of beverages is a dry process that avoids residues and the use of maximum allowable concentrations of established sterilants, e.g., hydrogen peroxide. PMID:18939764

Deilmann, Michael; Halfmann, Helmut; Bibinov, Nikita; Wunderlich, Joachim; Awakowicz, Peter

2008-10-01

22

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

Microsoft Academic Search

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

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

1998-01-01

23

Study of Inactivation Factors in Low Temperature Surface-wave Plasma Sterilization  

NASA Astrophysics Data System (ADS)

In this study we investigated the low temperature surface-wave plasma sterilization of directly and indirectly exposed Geobacillus stearothermophilus spores with a large-volume microwave plasma device. The air-simulated gas mixture was used to produce the plasma. The water vapor addition to the gas mixture improved the sterilization efficiency significantly. The effect of ultraviolet photons produced along with plasma to inactivate the spores was studied using a separate chamber, which was evacuated to less than one mTorr and was observed that spores were sterilized within 60 min. The scanning electron microscopy images revealed no significant changes in the actual size of the spores with that of untreated spores despite the survival curve shown that the spores were inactivated.

Singh, Mrityunjai Kumar; Xu, Lei; Ogino, Akihisa; Nagatsu, Masaaki

24

Fundamental aspects in the plasma surface interaction during plasma sterilization  

NASA Astrophysics Data System (ADS)

The inactivation of bacteria in oxygen or hydrogen containing low pressure plasmas is investigated by mimicking the plasma exposure with a dedicated beam experiment employing argon ions, oxygen molecules/atoms and hydrogen atoms . Thereby, fundamental inactivation mechanisms can be revealed. It is shown that the impact of O atoms or H atoms has no effect on the viability of bacterial spores and that no etching of the spore coat occurs up to an O and H atom fluence of 3.5 x 10^19 cm^-2. The impact of argon ions with an energy of 200 eV does not cause significant erosion for fluences up to 1.15 x 10^18 cm^-2. However, the combined impact of argon ions and oxygen molecules/atoms or H atoms causes significant etching of the spores and significant inactivation. This is explained by the process of chemical sputtering, where an ion induced defect at the surface of the spore reacts with either the incident bi-radical O_2 or with an incident O atom or H atom. This leads to the formation of CO, CO_2 and H_2O and thus to erosion. This beam results are compared to a broad sterilization campaign using an ICP reactor in a European round robin experiment BIODECON. Strategies for optimizing the plasma sterilization processes will be presented.

von Keudell, A.

2008-07-01

25

Plasma Sterilization of Selected Ophthalmic Instruments for Combined Intraocular Surgery  

Microsoft Academic Search

Plasma sterilization is a nontoxic fast procedure for thermolabile and thermostable microsurgical instruments. We report data on the microbicidal effectiveness for daily routine surgical instruments like steel scissors, trephination devices, microstripper and Vitro-Cat as well as irrigation\\/aspiration instruments. When these instruments were cleaned from blood and saline, and when H2O2 intensifiers (adapters) were applied where necessary plasma sterilization proved to

A. A. Bialasiewicz; M. Förtsch; A. Sammann; J. Draeger

1995-01-01

26

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

SciTech Connect

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.

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

27

Permeation barrier coating and plasma sterilization of PET bottles and foils  

NASA Astrophysics Data System (ADS)

Modern packaging materials such as polyethylene terephthalate (PET) offer various advantages over glass or metal containers. Beside this they only offer poor barrier properties against gas permeation. Therefore, the shelf-live of packaged food is reduced. Additionally, common sterilization methods like heat, hydrogen peroxide or peracetic acid may not be applicable due to reduced heat or chemical resistance of the plastic packaging material. For the plasma sterilization and permeation barrier coating of PET bottles and foils, a microwave driven low pressure plasma reactor is developed based on a modified Plasmaline antenna. The dependencies of important plasma parameters, such as gas mixture, process pressure, power and pulse conditions on oxygen permeation through packaging foil are investigated. A residual permeation as low as J = 1.0 ±0.3 cm^3m-2day-1bar-1 for 60 nm thick silicon oxide (SiOx) coated PET foils is achieved. To discuss this residual permeation, coating defects are visualized by capacitively coupled atomic oxygen plasma etching of coated substrate. A defect density of 3000 mm-2 is revealed responsible for permeation. For plasma sterilization, optimized plasma parameters based on fundamental research of plasma sterilization mechanisms permit short treatment times of a few seconds.

Steves, Simon; Deilmann, Michael; Bibinov, Nikita; Awakowicz, Peter

2009-10-01

28

Sterilization of bacterial endospores by an atmospheric-pressure argon plasma jet  

SciTech Connect

Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. However, the spore-killing efficiency of the atmospheric-pressure argon-oxygen jet depends very sensitively on the oxygen concentration in the argon gas.

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

2007-06-25

29

Atmospheric Plasma Sterilization and Deodorization of Dielectric Surfaces  

Microsoft Academic Search

A method is presented for rapid and uniform sterilization and deodorization of dielectric surfaces. The technology is applicable to the inside surface of PET or glass bottles, polymer caps, plastic tubes, etc. The treatment is based on a pulsed RF discharge in air at atmospheric pressure (eventually with addition of argon) creating a nonequilibrium plasma on the treated surface. The

P. Koulik; S. Begounov; S. Goloviatinskii

1999-01-01

30

[Sterilizing effect of atmospheric pressure plasma jet on microbes].  

PubMed

To study the sterilizing effect and mechanism of APPJ on microbes preliminarily, three representative bacteria, Staphylococcus aureus, Escherichia coli, Bacillus subtilis var. niger were treated by two kinds of plasma, DBD (dielectric barrier discharge) and APPJ. The survival curves of different microbes were compared and analyzed; Furthermore, the morphological change to cell walls and cell membranes were studied by scanning electric microscope. These results demonstrated that in the beginning phase the sterilizing effect of two kinds of plasmas on three microorganisms was stronger than in the later phase, and APPJ was more effective than DBD (D value of DBD on Bacillus subtilis var. niger was 70 s, whereas APPJ's was 4 s, much more efficient). Meanwhile, the gross morphological damage of E. coli cells under SEM after APPJ treatment was observed. These gave the obvious evidence that APPJ can destroy the microbes very efficiently, and more likely through the damage of cell walls and membranes of microbes treated by APPJ. PMID:15989284

Wu, Xu-Qin; Wang, Shou-guo; Han, Li; Zhao, Ling-li; Chang, Xiao; Chen, Geng; Suo, Ji-jiang; Xing, Yu-bin; Chen, Shi-ping

2005-04-01

31

Plasma-based ion implantation sterilization technique and ion energy estimation  

NASA Astrophysics Data System (ADS)

Plasma-based ion implantation (PBII) is applied as a sterilization technique for three-dimensional work pieces. In the sterilization process, a pulsed negative high voltage (5 ?s pulse width, 300 pulses/s,-800 V to -13 kV) is applied to the electrode (workpiece) under N2 at a gas pressure of 2.4 Pa. The resultant self-ignited plasma is shown to successfully reduce the number of active Bacillus pumilus cells by 105 times after 5 min of processing. The nitrogen ion energy is estimated using a simple method based on secondary ion mass spectroscopy analysis of the vertical distribution of nitrogen in PBII-treated Si.

Tanaka, T.; Watanabe, S.; Shibahara, K.; Yokoyama, S.; Takagi, T.

2005-07-01

32

Effect of dielectric and liquid on plasma sterilization using dielectric barrier discharge plasma.  

PubMed

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

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

2013-08-07

33

Estimation of Nitrogen Ion Energy in Sterilization Technology by Plasma Based Ion Implantation  

NASA Astrophysics Data System (ADS)

Plasma based ion implantation (PBII) with negative voltage pulses to the test specimen has been applied to the sterilization process as a technique suitable for three-dimensional work pieces. Pulsed high negative voltage (5 ?s pulse width, 300 pulses/s, -800 V to -15 kV) was applied to the electrode in this process at a gas pressure of 2.4 Pa of N2. We found that the PBII process, in which N2 gas self-ignitted plasma generated by only pulsed voltages is used, reduces the number of active Bacillus pumilus cell. The number of bacteria survivors was reduced by 10-5 x with 5 min exposure. Since the ion energy is the most important processing parameter, a simple method to estimate the nitrogen ion energy from distribution of nitrogen atoms in Si implanted by PBII was developed. The implanted ion energy is discussed from the SIMS in depth profiles.

Kondou, Youhei; Nakashima, Takeru; Tanaka, Takeshi; Takagi, Toshinori; Watanabe, Satoshi; Ohkura, Kensaku; Shibahara, Kentaro; Yokoyama, Shin

34

Comparative evaluation of the sporicidal activity of new low-temperature sterilization technologies: Ethylene oxide, 2 plasma sterilization systems, and liquid peracetic acid  

Microsoft Academic Search

Objective: This study was undertaken to evaluate the efficacy of 4 new low-temperature sterilization technologies: ethylene oxide with hydrochlorofluorocarbons, a liquid peracetic acid immersion system (Steris System 1 Processor), and 2 plasma sterilization processes that use vaporized hydrogen peroxide (Sterrad 100 and the Sterrad 100S). The Sterrad 100S system potentially improves sterilizer efficacy by using 2 cycles of a diffusion

William A. Rutala; Maria F. Gergen; David J. Weber

1998-01-01

35

The Effect of Air Plasma on Sterilization of Escherichia coli in Dielectric Barrier Discharge  

NASA Astrophysics Data System (ADS)

In this work, a Dielectric Barrier Discharge (DBD) air plasma was used to sterilize Escherichia coli (E. coli) on the surface of medical Polyethylene Terephthalate (PET) film. The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm, together with transmission electron microscopy (TEM) about cell morphology were performed after sterilization to analyse inactivation mechanisms. The results indicated that the DBD air plasma was very effective in E. coli sterilization. The plasma germicidal efficiency depended on the plasma treatment time, the air-gap distance, and the applied voltage. Within 5 min of plasma treatment, the germicidal efficiency against E. coli could reach 99.99%. An etching action on cell membranes by electrons, ions and radicals is the primary mechanism for DBD air plasma sterilization, which leads to the effusion of cellular contents (DNA and protein) and bacterial death.

Hu, Miao; Guo, Yun

2012-08-01

36

Sterilization of Staphylococcus Aureus by an Atmospheric Non-Thermal Plasma Jet  

NASA Astrophysics Data System (ADS)

An atmospheric non-thermal plasma jet was developed for sterilizing the Staphylococcus aureus (S. aureus). The plasma jet was generated by dielectric barrier discharge (DBD), which was characterized by electrical and optical diagnostics. The survival curves of the bacteria showed that the plasma jet could effectively inactivate 106 cells of S. aureus within 120 seconds and the sterilizing efficiency depended critically on the discharge parameter of the applied voltage. It was further confirmed by scanning electron microscopy (SEM) that the cell morphology was seriously damaged by the plasma treatment. The plasma sterilization mechanism of S. aureus was attributed to the active species of OH, N2+ and O, which were generated abundantly in the plasma jet and characterized by OES. Our findings suggest a convenient and low-cost way for sterilization and inactivation of bacteria.

Liu, Xiaohu; Hong, Feng; Guo, Ying; Zhang, Jing; Shi, Jianjun

2013-05-01

37

Chlorine Dioxide Gas Sterilization under Square-Wave Conditions  

PubMed Central

Experiments were designed to study chlorine dioxide (CD) gas sterilization under square-wave conditions. By using controlled humidity, gas concentration, and temperature at atmospheric pressure, standard biological indicators (BIs) and spore disks of environmental isolates were exposed to CD gas. The sporicidal activity of CD gas was found to be concentration dependent. Prehumidification enhanced the CD activity. The D values (time required for 90% inactivation) of Bacillus subtilis subsp. niger ATCC 9372 BIs were estimated to be 1.5, 2.5, and 4.2 min when exposed to CD concentrations of 30, 15, and 7 mg/liter, respectively, at 23°C and ambient (20 to 40%) relative humidity (RH). Survivor tailings were observed. Prehumidification of BIs to 70 to 75% RH in an environmental chamber for 30 min resulted in a D value of 1.6 min after exposure to a concentration of 6 to 7 mg of CD per liter at 23°C and eliminated survivor tailing. Prolonging prehumidification at 70 to 75% RH for up to 16 h did not further improve the inactivation rate. Prehumidification by ultrasonic nebulization was found to be more effective than prehumidification in the environmental chamber, improving the D value to 0.55 min at a CD concentration of 6 to 7 mg/liter. Based on the current observations, CD gas is estimated, on a molar concentration basis, to be 1,075 times more potent than ethylene oxide as a sterilant at 30°C. A comparative study showed B. subtilis var. niger BIs were more resistant than other types of BIs and most of the tested bacterial spores of environmental isolates.

Jeng, David K.; Woodworth, Archie G.

1990-01-01

38

Plasma sterilization of Geobacillus Stearothermophilus by O{mathsf2}:N{mathsf2} RF inductively coupled plasma  

NASA Astrophysics Data System (ADS)

The aim of this work is to identify the main process responsible for sterilization of Geobacillus Stearothermophilus spores in O{2}:N{2} RF inductively coupled plasma. In order to meet this objective the sterilization efficiencies of discharges in mixtures differing in the initial O{2}/N{2} ratios are compared with plasma properties and with scanning electron microscopy images of treated spores. According to the obtained results it can be concluded that under our experimental conditions the time needed to reach complete sterilization is more related to O atom density than UV radiation intensity, i.e. complete sterilization is not related only to DNA damage as in UV sterilization but more likely to the etching of the spore.

Kylián, O.; Sasaki, T.; Rossi, F.

2006-05-01

39

Chemico-physical modifications induced by plasma and ozone sterilizations on shape memory polyurethane foams.  

PubMed

Thermally activated shape memory polyurethane foams are promising materials for minimally invasive surgical procedures. Understanding their physical and chemical properties, in vitro response and effects of sterilization is mandatory when evaluating their potential as biomaterials. In this work, we report on the characterization of two Cold Hibernated Elastic Memory (CHEM) foams before and after two novel low-temperature sterilization techniques (plasma and ozone). Foams have different transition temperatures (T(trans)), as determined by Tandelta peaks in DMA tests, that depend on their chemical composition: both foams possess excellent shape recovery ability (Recovery Rate up to 99%) in conventional shape recovery tests. Plasma sterilization (Sterrad sterilization system) resulted in a slight increase of open porosity, but no effects on bulk chemical and thermo-mechanical properties were observed. Ozone sterilization had a stronger effect on foams morphology, both in terms of an evident rupture of pore walls and surface oxidation. These modifications affected both thermomechanical and shape recovery behavior. Furthermore, plasma sterilized foams cytocompatibility was investigated with L929 fibroblast cell line in vitro, showing a good adhesion and proliferation, as confirmed by SEM observation and Alamar blue assay. The obtained results contribute to define the role of shape memory foams as biomaterials and open novel questions on the role of sterilization technique effects on cellular solids. PMID:20407808

De Nardo, Luigi; Moscatelli, Monica; Silvi, Federica; Tanzi, Maria Cristina; Yahia, L'hocine; Farè, Silvia

2010-04-21

40

[H2O2 low temperature plasma sterilization. New possibilities for use with eye surgery instruments].  

PubMed

The H2O2-low-temperature-plasma-sterilization (STERRAD 100) works with a temperature below 50 degrees C (140 degrees F). This system is appliable for thermostabile materials as well as for thermolabile materials. The efficancy of this new system is shown by a biological test with Bacillus pumilus spores. 5 typical ophthalmic surgical instruments were contaminated. After sterilization the numerical reduction of the microorganisms had to be at least 6 log levels. Corrosion caused by hydrogene peroxide was excluded after exposing steal with a high quantity of this substrate. Electromicroscopy analysations of the surfaces of stainless steal after LTP, steam sterilization and hot-air sterilization are compared. Options and limitations of this new sterilization technique are discussed. A newly developed operating system with a complete instrumental box (OP-Set) will be introduced. PMID:8124049

Förtsch, M; Prüter, J W; Draeger, J; Helm, F; Sammann, A; Seibt, H; Ahlborn, H

1993-12-01

41

FAST TRACK COMMUNICATION: Ar + NO microwave plasmas for Escherichia coli sterilization  

NASA Astrophysics Data System (ADS)

Ar + NO microwave discharges are used for sterilization and the results are compared with additional experiments with Ar, O2 and N2-O2 plasma mixtures. The NO* species produced in the Ar-NO mixtures remain up to long distances from the source, thus improving the sterilization efficiency of the process. E. coli individuals exposed to the Ar + NO plasma undergo morphological damage and cell lysis. Combined effects of etching (by O* and Ar* species) and UV radiation (from deactivation of NO* species) are responsible for the higher activity found for this plasma mixture.

Hueso, José L.; Rico, Víctor J.; Frías, José E.; Cotrino, José; González-Elipe, Agustín R.

2008-05-01

42

Chemicophysical modifications induced by plasma and ozone sterilizations on shape memory polyurethane foams  

Microsoft Academic Search

Thermally activated shape memory polyurethane foams are promising materials for minimally invasive surgical procedures. Understanding\\u000a their physical and chemical properties, in vitro response and effects of sterilization is mandatory when evaluating their\\u000a potential as biomaterials. In this work, we report on the characterization of two Cold Hibernated Elastic Memory (CHEM) foams\\u000a before and after two novel low-temperature sterilization techniques (plasma

Luigi De Nardo; Monica Moscatelli; Federica Silvi; Maria Cristina Tanzi; L’Hocine Yahia; Silvia Farè

2010-01-01

43

Market Assessment: Natural Gas Fired Medical Sterilizers. Final Report, October 1991-April 1992.  

National Technical Information Service (NTIS)

The objective of this study was to assess the potential market for natural gas fired sterilization equipment. Two markets were investigated: on-site treatment and disposal of infectious waste, and resterilization of medical products. In both of these mark...

D. N. Larson K. D. Loving P. H. Norton

1992-01-01

44

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

PubMed

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

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

2013-01-01

45

Gas lens laser produced plasma.  

PubMed

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

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

1989-07-01

46

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

NASA Astrophysics Data System (ADS)

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.

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

1996-11-01

47

Analysis of Sterilization Effect of Atmospheric Pressure Pulsed Plasma  

SciTech Connect

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

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

2007-04-23

48

Sterrad Sterilization System: a new technology for instrument sterilization.  

PubMed

The Sterrad Sterilization System by Advanced Sterilization Products (ASP) exploits the synergism between peroxide and low temperature gas plasma (an excited or ionized gas) to rapidly destroy microorganisms (Figure 1). At the completion of the sterilization process based on this technology, no toxic residues remain on the sterilized items. The technology is particularly suited to the sterilization of heat and moisture sensitive instruments since process temperatures do not exceeded about 50 degrees C (140 degrees F) and sterilization occurs in a low moisture environment. Total process time is about one hour. The efficacy of the process has been demonstrated against a broad spectrum or microorganisms and on a large number of substrates used in medical instruments. PMID:8050015

Jacobs, P; Kowatsch, R

1993-02-01

49

Room temperature sterilization of surfaces and fabrics with a One Atmosphere Uniform Glow Discharge Plasma  

Microsoft Academic Search

  We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the One Atmosphere\\u000a Uniform Glow Discharge Plasma (OAUGDP). This newly-invented source of glow discharge plasma (the fourth state of matter) is\\u000a capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial active species to surfaces\\u000a and workpieces at room temperature

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

1998-01-01

50

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

Microsoft Academic Search

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

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

51

Battling Bacterial Biofilms with Gas Discharge Plasma  

NASA Astrophysics Data System (ADS)

Most studies dealing with growth and physiology of bacteria have been carried out using free-living cells. However, most bacteria live in communities referred to as biofilms where cooperative interactions among their members make conventional methods of controlling microbial growth often ineffective. The use of gas discharge plasmas represents an alternative to traditional decontamination/sterilization methods. We studied biofilms using two organisms, Chromobacterium violaceum and Pseudomonas aeruginosa. With the first organism we demonstrated almost complete loss of cell culturability after a 5-min plasma treatment. However, additional determinations showed that non-culturable cells were still alive after short exposure times. We have recently reported the effect of plasma on P. aeruginosa biofilms grown on borosilicate coupons. In this paper, we present results for plasma treatments of 1-, 3-, and 7-day old P. aeruginosa biofilms grown on polycarbonate or stainless-steel coupons. Results indicate nearly 100% of ­biofilm inactivation after 5 min of exposure with similar inactivation kinetics for 1-, 3-, and 7-day-old biofilms, and for both materials used. The inactivation kinetics is similar for both organisms, suggesting that the method is useful regardless of the type of biofilm. AFM images show changes in biofilm structure for various plasma exposure times.

Zelaya, Anna; Vandervoort, Kurt; Brelles-Mariño, Graciela

52

New sterilization technologies alternative to ethylene oxide  

Microsoft Academic Search

Sterilization of biomedical devices may induce bulk and surface modification, responsible for the decrease or loss of their biofunctionality. Pure ethylene oxide (EO) at low temperature and new alternative techniques such as cold gas plasma sterilization have been developed for heat-sensitive polymers. There is a lack of the knowledge concerning their safety in terms of materials damage and consequences on

Maryam Tabrizian; Sophie Lerouge; Anne Debrie; L'hocine Yahia

1997-01-01

53

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

PubMed Central

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

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

2012-01-01

54

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

SciTech Connect

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.

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

55

Safety of plasma-based sterilization: surface modifications of polymeric medical devices induced by Sterrad and Plazlyte processes.  

PubMed

Plasma-based sterilization is a promising alternative to the use of pure ethylene oxide (EO), for low-temperature clinical sterilization of medical instruments and devices. However, few studies have been published that evaluate its safety in terms of possible damage to materials, particularly polymers. The objective of this work was to evaluate polymer surface modifications induced by commercial plasma-based sterilizers, in comparison with pure EO: Samples from 5 polymer-based devices were subjected to 1, 5, and 10 sterilization cycles by Sterrad-100, Plazlyte, and pure EO. Surface analysis was carried out by X-ray photoelectron spectroscopy (XPS), dynamic contact angle measurements (DCA), and scanning electron microscopy (SEM). Surface oxidation and wettability changes were observed on all samples sterilized by plasma-based techniques, the degree of modifications depending on the sterilizer (Sterrad, Plazlyte) and the type of polymer. Drastic changes of surface appearance were also observed by SEM on PVC samples sterilized by Plazlyte and by pure EO. Possible repercussions on safety are discussed. PMID:11847405

Lerouge, S; Tabrizian, M; Wertheimer, M R; Marchand, R; Yahia, L'H

2002-01-01

56

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

PubMed

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

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

2013-06-21

57

Reuse of healing abutments: an in vitro model of plasma cleaning and common sterilization techniques.  

PubMed

The reuse of transgingival healing abutments has been advocated by several implant manufacturers, but cleaning and sterilization procedures to yield clean and optimal surfaces have yet to be developed. The objective of this in vitro project was to investigate various cleaning and sterilization regimens for the removal of biological debris to support reattachment of subgingival connective tissue. Simulated clinical healing abutment surfaces were exposed to culture medium with serum for 1 hour to simulate biological exposure. Simulated healing abutment surfaces not contaminated by serum were used to represent the "as-is" healing abutment surface without prior in vivo use. The discs were cleaned with detergent before sterilization by ultraviolet light (UV) or steam autoclaving (AC) both with and without 1- and 5-minute plasma cleaning (PC). A series of surface analytical techniques (XPS, AES, and surface contact angles) and in vitro analysis of cell attachment and spreading using gingival fibroblasts were performed. After exposure to the simulated biological conditions, clinical cleaning followed by UV resulted in contaminated surfaces and relatively high levels of cell attachment. PC before UV treatment enhanced surface energetics but did not affect cell attachment and spreading. AC increased surface wetting angles; which were decreased somewhat by previous PC. Cell attachment was significantly reduced by AC. Although some increase in cell attachment after longer plasma cleaning was noted in the AC group, no difference in cell spreading was seen in any AC group. Cell spreading seemed to be less for all AC groups compared with all UV, as-is, and control groups. Although certain cleaning (PC) and sterilization (UV) procedures can be effective for cleaning transgingival healing abutments, those using AC are questionable due to their propensity for organic and inorganic contamination and unfavorable surface alteration. PMID:11307410

Vezeau, P J; Keller, J C; Wightman, J P

2000-01-01

58

Plasma-based sterilization: effect on surface and bulk properties and hydrolytic stability of reprocessed polyurethane electrophysiology catheters.  

PubMed

Plasma-based sterilization is a promising alternative to ethylene oxide (EO) for reprocessing of electrophysiology catheters. To assess its safety in terms of material damage, modifications of surface and bulk properties as well as hydrolytic stability of sterilized catheters were evaluated. Polyurethane (PU) single-use electrophysiology catheters were subjected to one, five, and ten sterilization cycles by Sterrad-100S and Plazlyte, as well as by pure EO for comparison. Surface analysis techniques (ATR-FTIR, XPS, DCA) showed oxidation limited to the near-surface layer induced by both plasma-based sterilizers, whereas EO induced slight but deeper alkylation. Using bulk analysis techniques (RP-HPLC, SEC), oligomer alteration was observed after all three sterilization techniques, without modification of molecular weights. Hydrolytic stability of catheters was slightly changed by plasma-based sterilization, with a small increase in released oligomers. Finally, although Plazlyte and Sterrad are both plasma-based techniques, they induced different impacts on catheters, such as the degradation of an additive with Sterrad, and a clear difference in coloration with Plazlyte. PMID:11033561

Lerouge, S; Guignot, C; Tabrizian, M; Ferrier, D; Yagoubi, N; Yahia, L

2000-12-15

59

Low pressure plasma discharges for the sterilization and decontamination of surfaces  

NASA Astrophysics Data System (ADS)

The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O2 mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their de-activation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.

Rossi, F.; Kylián, O.; Rauscher, H.; Hasiwa, M.; Gilliland, D.

2009-11-01

60

An overview of research using the one atmosphere uniform glow discharge plasma (OAUGDP) for sterilization of surfaces and materials  

Microsoft Academic Search

The medical, food processing, and heating, ventilating, and air conditioning industries are searching for improved pasteurization, disinfection, and sterilization technologies. Candidate techniques must deal with and overcome such problems as thermal sensitivity and destruction by heat, formation of toxic by-products, costs, and inefficiency in performance. We report the results of a plasma source, the One Atmosphere Uniform Glow Discharge Plasma

Thomas C. Montie; Kimberly Kelly-Wintenberg; J. Reece Roth

2000-01-01

61

Gas plasma treatment: a new approach to surgery?  

PubMed

In this survey we analyse the status quo of gas plasma applications in medical sciences. Plasma is a partly ionized gas, which contains free charge carriers (electrons and ions), active radicals, and excited molecules. So-called nonthermal plasmas are particularly interesting, because they operate at relatively low temperatures and do not inflict thermal damage to nearby objects. In the past two decades nonthermal plasmas have made a revolutionary appearance in solid state processing technology. The recent trends focus on using plasmas in health care, for "processing" of medical equipment and even living tissues. The major goal of tissue treatment with plasmas is nondestructive surgery: controlled, high-precision removal of diseased sections with minimum damage to the organism. Furthermore, plasmas allow fast and efficient bacterial inactivation, which makes them suitable for sterilization of surgical tools and local disinfection of tissues. Much research effort must be undertaken before these techniques will become common in medicine, but it is expected that a novel approach to surgery will emerge from plasma science. PMID:15658931

Stoffels, Eva; Kieft, Ingrid E; Sladek, Raymond E J; van der Laan, Ewout P; Slaaf, Dick W

2004-01-01

62

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

Microsoft Academic Search

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

Katarzyna Gorna; Sylwester Gogolewski

2003-01-01

63

PLASMA CATALYTIC REFORMING OF NATURAL GAS  

Microsoft Academic Search

In this paper, recent results of plasma processing of natural gas are described. The use of a plasma reformer for the generation of hydrogen rich gas from natural gas has been investigated. In an accompanying paper, progress in plasma reforming of diesel fuel is described. The reformate composition has been investigated as a function of the initial mixture of air

L. Bromberg; A. Rabinovich; N. Alexeev; D. R. Cohn

64

New sterilization technologies alternative to ethylene oxide  

NASA Astrophysics Data System (ADS)

Sterilization of biomedical devices may induce bulk and surface modification, responsible for the decrease or loss of their biofunctionality. Pure ethylene oxide (EO) at low temperature and new alternative techniques such as cold gas plasma sterilization have been developed for heat-sensitive polymers. There is a lack of the knowledge concerning their safety in terms of materials damage and consequences on the biofunctionality of sterilized devices. The objective of our work consists in studying bulk and surface changes in biomedical devices induced by these two sterilization techniques. Samples from PVC, Polyurethane, Polyacrylate and Polyethylene-based medical devices are subjected to 1, 5, and 10 sterilization cycles by Steri-Vac-3M (pure EO), Sterrad-100$TM, J&J (gas plasma + H2O2), and studied by X-rays photoelectron spectroscopy. Preliminary results show an increasing in Oxygen/Carbon ratio by a factor of 1.3 to 4.4 between the first and tenth cycle indicating the surface oxidation by gas plasma sterilization processes. Some changes in C-C chemical bounding are associated with EO sterilization.

Tabrizian, Maryam; Lerouge, Sophie; Debrie, Anne; Yahia, L'hocine

1997-06-01

65

Space hardware compatibility tests with hydrogen peroxide gas plasma sterilization  

Microsoft Academic Search

The exploration of the Solar System shall comply with planetary protection requirements handled presently by the Committee of Space Research (COSPAR). The goal of planetary protection is to protect celestial bodies from terrestrial contamination and also to protect the Earth environment from an eventual contamination carried by return samples or by space systems. For project teams, avoiding the biological contamination

Delphine Faye; Alexandre Aguila; Andre Debus; Stephanie Remaury; Pascale Nabarra; Jacques C. Darbord; Caroline Soufflet; Philippe Destrez; Patrice Coll; David Coscia

2008-01-01

66

Ternary Arc Gas Plasma Welding Torch.  

National Technical Information Service (NTIS)

A plasma arc welding torch wherein a first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a l...

D. J. Rybicki W. F. Mcgee D. J. Waldron

1993-01-01

67

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

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

68

Low-temperature sterilization alternatives in the 1990s  

SciTech Connect

Vapor phase hydrogen peroxide, gas plasma, ozone, and peracetic acids have been commercialized as alternative technologies for low-temperature sterilization. None are viewed as a total replacement for ethylene oxide for on-site sterilization of reusable, heat-sensitive medical materials in healthcare facilities.

Schneider, P. (3M Center, St. Paul, MN, (United States). Surgical Div.)

1994-01-01

69

Ternary arc gas plasma welding torch  

NASA Astrophysics Data System (ADS)

A plasma arc welding torch wherein a first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a longitudinal bore in the electrode. The second plasma gas enters one end of the electrode and exits the electrode at the tip thereof for co-acting with the electric welding arc to produce the desired weld. A shield gas is directed through the torch body for circulating around the head of the torch adjacent to the electrode tip.

Rybicki, Daniel J.; McGee, William F.; Waldron, Douglas J.

1993-12-01

70

Shape memory polymer foams for cerebral aneurysm reparation: effects of plasma sterilization on physical properties and cytocompatibility.  

PubMed

Shape memory polyurethanes (SMPUs) represent promising candidate materials for aneurysm embolization, since they could enable clinical problems still associated with these clinical procedures to be overcome. In this work, we report on the characterization of physicochemical, thermomechanical and in vitro interface properties of two SMPU foams (Cold Hibernated Elastic Memory, CHEM), proposed as a material for embolization devices in minimally invasive procedures. Moreover, because device sterilization is mandatory for in vivo applications, effects on the properties of the foams after plasma sterilization were also evaluated. Both foams (CHEM 3520 and CHEM 5520) showed excellent shape recovery ability (recovery rate, R(r), up to 99%) in conventional shape recovery tests, performed at constant heating rate. Transition temperatures (T(trans)), determined by tandelta peaks in dynamic mechanical analysis (DMA), were 32.2 and 45.1 degrees C, for CHEM 3520 and 5520, respectively. The value of T(trans) affects shape memory ability in the recovery test at 37 degrees C, which simulates the behavior after implantation of the device: in fact, R(r) was significantly higher for lower T(trans) foam (R(r) approximately 82% and R(r) approximately 46%, respectively, for CHEM 3520 and CHEM 5520). After plasma sterilization performed by a Sterrad sterilization system, an increase in open porosity was observed: this is probably due to the sterilization cycle; however, no effects on shape recovery behavior were observed. Furthermore, plasma treatment had no significant effect on L929 cells in in vitro cytotoxicity tests, performed on cell culture medium extracts in contact with foams for up to 7 days. Moreover, direct cytocompatibility tests showed a good colonization and growth from L929 cells on CHEM foams, suggesting the effectiveness of an in vivo healing process. All these results seem to suggest that CHEM foams could be advantageously used for manufacturing devices for mini-invasive embolization procedures of aneurysms. PMID:19136318

De Nardo, Luigi; Alberti, Rachele; Cigada, Alberto; Yahia, L'Hocine; Tanzi, Maria Cristina; Farè, Silvia

2008-12-13

71

TOPICAL REVIEW: Striations in rare gas plasmas  

Microsoft Academic Search

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

Vladimir I. Kolobov

2006-01-01

72

Supercritical Carbon Dioxide Sterilization of UltraHigh Molecular Weight Polyethylene  

Microsoft Academic Search

Abstract The aim of this research was to use a benign,technique for the sterilization of ultra-high molecular weight polyethylene (UHMWPE), which is broadly used in artificial joints and other medical implants. Current sterilizations methods such as gamma irradiation, ethylene oxide gas, and gas plasma can damage the polymer, thus reducing its service life, as well as create harmful byproducts. Supercritical

John Carlos Titone

73

Application of Plasma on Reentry Vehicle Communication and Interplanetary Spacecraft Sterilization  

NASA Astrophysics Data System (ADS)

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).

Fenstermacher, Jarrod J.

74

Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Microbial biofilms are a functional matrix of microbial cells, enveloped in polysaccharides, enzymes and virulence factors secreted by them that can develop on indwelling medical devices and biomaterials. Plasma sterilization has been widely studied in recent years for biological applications. In this study, we evaluated the possibility of removal and anti-recovery of biofilms by microwave-induced argon plasma at atmospheric pressure. We observed that all bacterial biofilms formatted by Gram-negative and Gram-positive bacteria are removed in less than 20 s, and the growth inhibitions of planktonic bacteria within biofilms are also confirmed by plasma exposure for 5 s. These results suggest that our plasma system can be applied to medical and biological fields where the removal of biofilms and their debris is required.

Lee, Mi Hee; Park, Bong Joo; Jin, Soo Chang; Kim, Dohyun; Han, Inho; Kim, Jungsung; Hyun, Soon O.; Chung, Kie-Hyung; Park, Jong-Chul

2009-11-01

75

Bacterial inactivation using a low-temperature atmospheric plasma brush sustained with argon gas.  

PubMed

This study investigated the bacterial inactivation/sterilization effects of a new atmospheric plasma source, which is a brush-shaped argon glow discharge created under 1 atm pressure. Such an atmospheric plasma brush requires extremely low power of less than 20 W to operate; and therefore is essentially a low-temperature discharge as confirmed by gas-phase temperature measurements. Two bacteria, Escherichia coli (E. coli) and Micrococcus luteus (M. luteus), seeded in various media were subjected to plasma treatment and their survivability was examined. It was found that such argon atmospheric plasma brush is very effective in destruction of the bacteria cells. With nutrient broth and standard methods agar as supporting media, a cell reduction in a level of 6 orders of magnitude was observed for E. coli within 3-4 min plasma treatment. A similar level of cell reduction was also observed for M. luteus in the two media with 2 or 3 min plasma treatment. The plasma treatment effects on the bacteria cell structures were also examined using scanning electron microscopy and the cell structure damages due to the plasma exposure were observed on both bacteria. The possible sterilization mechanism of the argon plasmas is also discussed in this article. PMID:16850477

Yu, Q S; Huang, C; Hsieh, F-H; Huff, H; Duan, Yixiang

2007-01-01

76

Molecular mechanism of plasma sterilization in solution with the reduced pH method: importance of permeation of HOO radicals into the cell membrane  

NASA Astrophysics Data System (ADS)

Sterilization of certain infected areas of the human body surface is necessary for dental and surgical therapies. Because the blood is filled with body fluid, sterilization in solution is essential. In vitro solution sterilization has been successively carried out using a combination of low-temperature atmospheric-pressure plasma and the reduced pH method, where the solution is sufficiently acidic. Here, we show the molecular mechanism of such plasma sterilization in solution based on microbiology. Three kinds of bacteria were inactivated by plasma treatment under various pH conditions. The theoretical and experimental models revealed that the sterilization was characterized by the concentration of hydroperoxy radicals (HOO·), which were dependent on the pH value. Bacterial inactivation rates were proportional to the HOO· concentrations calculated by the theoretical model. To evaluate the penetration of radicals into the cell membrane, a bacterial model using dye-included micelles was used. Decolouration rates of the model were also in proportion with the calculated HOO· concentrations. These results indicate that the key species for plasma sterilization were hydroperoxy radicals. More importantly, the high permeation of hydroperoxy radicals into the cell membrane plays a key role for efficient bactericidal inactivation using the reduced pH method.

Takai, Eisuke; Ikawa, Satoshi; Kitano, Katsuhisa; Kuwabara, Junpei; Shiraki, Kentaro

2013-07-01

77

Validation of a low-temperature, low-pressure, vaporized aqueous hydrogen peroxide-based, plasma sterilization system - STERRAD ® 100S sterilizer  

Microsoft Academic Search

As in the past decade more medical devices have been introduced that are not only fragile but also (very) temperature sensitive, new avenues were searched to circumvent the traditional (tedious) methods of sterilization with equal sterilization efficacy. With the introduction of the new ISO 14937 guideline (\\

A. A. van Sorge; E. W. Ackerman; R. E. van der Werf

78

Surgery, sterilization and sterility.  

PubMed

The history of sterilization was not linked from the first with surgery. Surgery came first, fully 600 years before the principles of asepsis and anesthesia were even introduced in the middle of the 1800s. Also in the 1800s, the beginnings of thermal sterilization were being developed in the food industry. The basic principles of antisepsis and prevention of wound suppuration, including the destruction of germs on instruments, dressings, the hands of the surgeon and his assistants, and everything else in contact with the wound were clearly elucidated by Lister in the 1870s and remain the inviolate principles of surgical asepsis today. In general, the marriage between the surgeons and the sterilizers was a successful one; the major handicap to eternal bliss and harmony, however, was an incompatibility between the partners. As in many marriages, the partners made unwarranted demands upon each other, and became frustrated when these demands were unfulfilled. The field of surgical sterilization and surgical safety is less confused by technical inconsistencies than it is by semantic nightmares, such that we will never reach a universal definition of sterility. However, we do not really need a universal definition of sterility. Rather we should learn how to translate sterility tests in terms of the real world infections hazards. PMID:10124472

Green, V W

1993-03-01

79

Sterile technique  

MedlinePLUS

Sterile gloves ... water and soap A sterile kit or pad Gloves (sometimes these are in your kit) A clean, ... of the pad. Throw the wrapper away. Your gloves may be separate or inside your sterile kit. ...

80

Sterilization systems  

SciTech Connect

This book discusses and describes different sterilization methods which are used in industry, research laboratories, and hospitals. Treatment of infectious waste by sterilization has also been discussed.

Banerjee, K.; Cheremisinoff, P.N.

1985-01-01

81

Speciation analysis by gas chromatography with plasma source spectrometric detection  

Microsoft Academic Search

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

Ryszard ?obi?ski; Freddy C. Adams

1997-01-01

82

Plasma deposited polymers as gas sensitive films  

NASA Astrophysics Data System (ADS)

The possibility is presented of producing thin plasma polymers with desired properties by using nanofillers. Composite films are synthesized from a mixture of hexamethyldisiloxane (HMDSO) and detonation nanodiamond particles (DNDs). The chemical structure of the composite consists of DNDs distributed in the polymer matrix. The effect of DNDs on the humidity and ammonia sorptive properties of the polymers obtained is studied by measuring the mass changes as a result of gas sorption by using a quartz crystal microbalance (QCM). The results show that, in view of building a sensing element for measuring humidity, ammonia or other gases, it is possible to maximize the sensor sensitivity to a certain gas by using an appropriate concentration of DNDs in HMDSO. Thus, a high degree of sensor sensitivity, together with short response time and minimum hysteresis, can be achieved. Composites of plasma-polymerized HMDSO with DNDs can be used as gas sensitive layers for the development of quartz resonator sensors.

Radeva, E.; Georgieva, V.; Lazarov, J.; Vergov, L.; Donkov, N.

2012-03-01

83

Supersonic gas injector for plasma fueling  

SciTech Connect

A supersonic gas injector (SGI) has been developed for fueling and diagnostic applications on the National Spherical Torus Experiment (NSTX). It is comprised of a graphite converging-diverging Laval nozzle and a commercial piezoelectric gas valve mounted on a movable probe at a low field side midplane port location. Also mounted on the probe is a diagnostic package: a Langmuir probe, two thermocouples and five pickup coils for measuring toroidal, radial, vertical magnetic field components and magnetic fluctuations at the location of the SGI tip. The SGI flow rate is up to 4 x 10{sup 21} particles/s, comparable to conventional NSTX gas injectors. The nozzle operates in a pulsed regime at room temperature and a reservoir gas pressure up to 0.33 MPa. The deuterium jet Mach number of about 4, and the divergence half-angle of 5{sup o}-25{sup o} have been measured in laboratory experiments simulating NSTX environment. In initial NSTX experiments reliable operation of the SGI and all mounted diagnostics at distances 1-20 cm from the plasma separatrix has been demonstrated. The SGI has been used for fueling of ohmic and 2-4 MW NBI heated L- and H-mode plasmas. Fueling efficiency in the range 0.1-0.3 has been obtained from the plasma electron inventory analysis.

Soukhanovskii, V A; Kugel, H W; Kaita, R; Roquemore, A L; Bell, M; Blanchard, W; Bush, C; Gernhardt, R; Gettelfinger, G; Gray, T; Majeski, R; Menard, J; Provost, T; Sichta, P; Raman, R

2005-09-30

84

Nonmonotonic plasma density profile due to neutral-gas depletion  

SciTech Connect

The dependencies in a gas discharge of the plasma density and of the neutral-gas depletion on the magnetic-field intensity and on the plasma particle flux are studied. It is shown that if plasma particle flux density outward of the discharge is fixed, varying the magnetic field intensity does not affect neutral-gas depletion. When there are plasma end losses along magnetic-field lines while neutral-gas is depleted, an increase in the magnetic field intensity results in a nonmonotonic plasma density profile across field lines. The plasma density then has a local minimum at the center of the discharge.

Fruchtman, A. [H.I.T.-Holon Institute of Technology, 52 Golomb St., Holon 58102 (Israel)

2010-02-15

85

Sterilization/disinfection of medical devices using plasma: the flowing afterglow of the reduced-pressure N2-O2 discharge as the inactivating medium  

NASA Astrophysics Data System (ADS)

Potential sterilization/disinfection of medical devices (MDs) is investigated using a specific plasma process developed at the Université de Montréal over the last decade. The inactivating medium of the microorganisms is the flowing afterglow of a reduced-pressure N2-O2 discharge, which provides, as the main biocidal agent, photons over a broad ultraviolet (UV) wavelength range. The flowing afterglow is considered less damaging to MDs than the discharge itself. Working at gas pressures in the 400—700 Pa range (a few torr) ensures, through species diffusion, the uniform filling of large volume chambers with the species outflowing from the discharge, possibly allowing batch processing within them. As a rule, bacterial endospores are used as bio-indicators (BI) to validate sterilization processes. Under the present operating conditions, Bacillus atrophaeus is found to be the most resistant one and is therefore utilized as BI. The current paper reviews the main experimental results concerning the operation and characterization of this sterilizer/disinfector, updating and completing some of our previously published papers. It uses modeling results as guidelines, which are particularly useful when the corresponding experimental data are not (yet) available, hopefully leading to more insight into this plasma afterglow system. The species flowing out of the N2-O2 discharge can be divided into two groups, depending on the time elapsed after they left the discharge zone as they move toward the chamber, namely the early afterglow and the late afterglow. The early flowing afterglow from a pure N2 discharge (also called pink afterglow) is known to be comprised of N2+ and N4+ ions. In the present N2-O2 mixture discharge, NO+ ions are additionally generated, with a lifetime that extends over a longer period than that of the nitrogen molecular ions. We shall suppose that the disappearance of the NO+ ions marks the end of the early afterglow regime, thereby stressing our intent to work in an ion-free process chamber to minimize damage to MDs. Therefore, operating conditions should be set such that the sterilizer/disinfector chamber is predominantly filled by N and O atoms, possibly together with long-lived metastable-state O2(1 ?g) (singlet-delta) molecules. Various aspects related to the observed survival curves are examined: the actual existence of two “phases” in the inactivation rate, the notion of UV irradiation dose (fluence) and its implications, the UV photon best wavelength range in terms of inactivation efficiency, the influence of substrate temperature and the reduction of UV intensity through surface recombination of N and O atoms on the object/packaging being processed. To preserve their on-shelf sterility, MDs are sealed/wrapped in packaging material. Porous packaging materials utilized in conventional sterilization systems (where MDs are packaged before being subjected to sterilization) were tested and found inadequate for the N2-O2 afterglow system in contrast to a (non-porous) polyolefin polymer. Because the latter is non-porous, its corresponding pouch must be kept unsealed until the end of the process. Even though it is unsealed, but because the opening is very small the O2(1?g) metastable-state molecules are expected to be strongly quenched by the pouch material as they try to enter it and, as a result, only N and O atoms, together with UV photons, are significantly present within it. Therefore, by examining a given process under pouch and no-pouch conditions, it is possible to determine what are the inactivating agents operating: (i) when packaged, these are predominantly UV photons, (ii) when unpackaged, O2(1?g) molecules together with UV photons can be acting, (iii) comparing the inactivation efficiency under both packaged and unpackaged conditions allows the determination of the relative contribution of UV photons (if any) and O2(1?g) metastable-state molecules. Such a method is applied to pyrogenic molecules and to the enzymatic activity of lysozyme proteins once exposed to the N2-O2 flowing afterglow

Moisan, Michel; Boudam, Karim; Carignan, Denis; Kéroack, Danielle; Levif, Pierre; Barbeau, Jean; Séguin, Jacynthe; Kutasi, Kinga; Elmoualij, Benaïssa; Thellin, Olivier; Zorzi, Willy

2013-07-01

86

Properties of Hybrid Water\\/Gas DC Arc Plasma Torch  

Microsoft Academic Search

A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow was investigated. This hybrid water\\/gas stabilization offers the possibility of adjusting plasma jet parameters within a wide range from high-enthalpy low-density plasmas typical for liquid stabilized torches to lower enthalpy higher density plasmas generated in gas stabilized torches. The torch was operated

Milan Hrabovsky; V. Kopeckykopecky; Viktor Sember; Tetyana Kavka; Oleksiy Chumak; Milos Konrad

2006-01-01

87

Design of experiments on a DC Steady State Atmospheric Pressure Plasma Sterilizer  

NASA Astrophysics Data System (ADS)

Our Resistive Barrier Discharge has been demonstrated to be successful on E. coli, Pseudomonas fluorescens (5RL), spores and bacteriophages. It has been tested successfully in sterilizing pagers at the St. Jude Research Hospital in Memphis, TN. In this recent work, we evaluate three primary factors in the atmospheric pressure resistive barrier discharge, hydrogen peroxide, charged ions and air (oxygen). The experiment used was Analysis of Variance (ANOVA) and regression analysis. The tests used 144 Petri Dishes and the bacteria used were E. coli. The hydrogen peroxide was used as a replacement for the water conductor on the resistive barrier discharge electrode. The charged ions were removed by a double charged wire mesh between the discharge and the Petri Dish. The air was displaced by a slow flow of nitrogen into the experimental area. The basic conclusions are that air, and charged ions are both extremely effective in killing bacteria. In addition, air and charged ions together strongly enhance each other. Hydrogen peroxide in our experiments did not enhance the kill rate.

Alexeff, Igor; Balasundaram, Arun; Sawheny, Rapinder

2009-11-01

88

Direct Decomposition of Anesthetic Gas by Atmospheric Multi-Gas Inductively Coupled Plasma Source  

Microsoft Academic Search

In our research group, multi-gas ICP (inductively coupled plasma) source was developed for industrial plasma processing and traced elemental analysis. With the multi-gas ICP source, not only Ar but He, O2, N2, CO2, air and their mixture gas plasmas can be stably generated in atmospheric pressure. In this study, the plasma source was applied for decomposition of anesthetic gas which

Yu Goto; Ryota Sasaki; Hidekazu Miyahara; Eiki Hotta; Akitoshi Okino

2010-01-01

89

Fuel gas production by microwave plasma in liquid  

NASA Astrophysics Data System (ADS)

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.

Nomura, Shinfuku; Toyota, Hiromichi; Tawara, Michinaga; Yamashita, Hiroshi; Matsumoto, Kenya

2006-06-01

90

Fuel gas production by microwave plasma in liquid  

SciTech Connect

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.

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

91

Atmospheric Electrodeless Microwave Plasma-torch for Gas Decomposition  

Microsoft Academic Search

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

J. H. Kim; Y. C. Hong; H. S. Uhm

2001-01-01

92

Transcervical sterilization.  

PubMed

Sterilization is frequently chosen as a method of permanent contraception. Traditional approaches involve surgery under anesthesia in an operating room and are associated with a recovery period and scars. Transcervical sterilization is an incision-free, minimally invasive approach to sterilization. When compared with laparoscopic surgery, transcervical hysteroscopic sterilization does not need to be performed in an operating room, requires less anesthesia, has a shorter recovery period, and is more cost effective. The Essure Permanent Birth Control System (Conceptus, Inc., Mountain View, CA) and Adiana Permanent Contraception System (Hologic, Inc., Bedford, MA) are two available hysteroscopic sterilization techniques. They cause fibrosis and tubal occlusion over a 3-month period so women must use an alternative form of contraception during the first 3 months. A 3-month hysterosalpingogram confirms successful placement and tubal occlusion. Transcervical sterilization is similarly effective to other sterilization methods and is satisfactory to women. PMID:20352559

Castaño, Paula M; Adekunle, Lola

2010-03-29

93

Gas temperature in an alkali plasma  

NASA Astrophysics Data System (ADS)

A method is proposed for determining the gas temperature in a weakly ionized alkali vapor plasma from the measured ratio of the concentrations of the atoms and diatomic molecules of the same element. Criteria of the applicability of the method are obtained through a quantitative analysis of an equation of the balance of the number of dimers including possible processes of their formation and disintegration. The rate constants of three-particle atom-atom recombination in potassium, rubidium, and cesium vapors, required for the above analysis, are determined experimentally.

Lukashenko, V. I.; Pitatelev, G. V.

94

Pulse operated multi-gas inductively coupled plasma source  

Microsoft Academic Search

Summary form only given. A new atmospheric pulse operated multi-gas ICP (inductively coupled plasma) source is developed. With our multi-gas ICP source, not only Ar but He, O2, N2, CO2, air and their mixture gas plasma can be stably generated in the atmospheric pressure. Furthermore, aqueous solutions can be introduced directly into the plasmas using common pneumatic nebulizers. To generate

A. Okino; H. Miyahara; K. Takimoto; T. Kageyasu; M. Watanabe; E. Hotta

2006-01-01

95

Furnace atomization plasma emission spectrometry with He\\/Ar mixed gas plasmas  

Microsoft Academic Search

The influence of plasma gas composition on the operating and analytical characteristics of a furnace atomization plasma emission source (FAPES) is presented. He I and Ar I excitation temperatures increase 30% in the mixed gas plasmas whereas argon ion excitation temperatures decrease from 33000 K to 26000 K in the presence of He. Collisional exchange of internal energy between excited

Fusheng Sun; Ralph E. Sturgeon

1999-01-01

96

Microwave sterilization.  

PubMed

This study has shown that representative fungi, viruses, and aerobic and anaerobic bacteria, including spore formers, can easily be killed in a conventional microwave oven with proper modifications. Metal instruments, including air turbine handpieces and burs, and acrylic dentures can be sterilized in short periods. Consistent sterilization can be accomplished only if the items to be sterilized are rotated in a three-dimensional manner throughout the microwave cavity. Arcing back to the magnetron and damage to the microwave oven are prevented by placing a radar absorbent material within the oven and with proper insulation of the item to be sterilized. PMID:3884686

Rohrer, M D; Bulard, R A

1985-02-01

97

Sterilization effects on starPEG coated polymer surfaces: characterization and cell viability.  

PubMed

Sterilization is frequently an issue for polymeric biomaterials including hydrogels, where autoclaving needs to be discarded, and gamma-irradiation and low temperature hydrogen peroxide gas plasma sterilization are already important alternatives. Coatings based on poly(ethylene glycol) are a well-known strategy to reduce unspecific protein interactions on biomaterial surfaces. Dense, ultrathin coatings of isocyanate terminated star-shaped poly(ethylene glycol) (starPEG) molecules have proven to be resistant to unspecific adsorption of proteins and enable direct biofunctionalization. The effectivity and stability of the starPEG coatings on poly(vinylidene fluoride) (PVDF) were studied after gamma-irradiation (normed dosis 25 kGy) and plasma sterilization (Sterrad 100S). The selected surface properties determined were: surface composition (X-ray photoelectron spectroscopy, XPS), wettability (sessile drop contact angle) and protein adsorption by fluorescence microscopy (Avidin-TexasRed, Bovine Serum Albumin-Rhodamin). Preliminary cell experiments with the cell line L929 were performed prior and after sterilization to investigate the cell repellence of the starPEG coatings as well as cell viability and specific cell adhesion on GRGDS-modified coatings. The starPEG coating undergoes a slight oxidation due to plasma and gamma-sterilization; this represents a minor variation confirmed by XPS and contact angle results. The non-sterilized starPEG and the plasma-sterilized coatings are protein repellent, however the protein adsorption on starPEG coated substrates is much stronger after gamma-sterilization for both avidin and bovine serum albumin. The cell experiments indicate that the starPEG coatings are appliable homogeneously by incubation and are non-cell adherent. Moreover, after both sterilization processes the starPEG coatings remain cell repellent and the GRGDS-modified coatings presented vital cells. Thus we conclude that the plasma sterilization is more convenient for the starPEG coatings and GRGDS-modified starPEG coatings. PMID:18228118

Lleixà Calvet, Júlia; Grafahrend, Dirk; Klee, Doris; Möller, Martin

2008-01-29

98

Tubal Sterilization  

MedlinePLUS

... pills, you will likely have irregular periods after sterilization. As women get older, their periods change. How often your ... can be rejoined, pregnancy isn't guaranteed. Many women can't try reversals because there's not enough of their ... Source Counseling Issues in Tubal Sterilization by I. Cori Baill, M.D., Vanessa E. ...

99

New disinfection and sterilization methods.  

PubMed

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

Rutala, W A; Weber, D J

100

New disinfection and sterilization methods.  

PubMed Central

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).

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

2001-01-01

101

Velocity limitations in coaxial plasma gun experiments with gas mixtures  

Microsoft Academic Search

The velocity limitations found in many crossed field plasma experiments with neutral gas present were studied for binary mixtures of H2, He, N2, O2, Ne, and Ar. The apparatus used was a coaxial plasma gun with an azimuthal magnetic bias field. The discharge parameters were chosen so that the plasma was weakly ionized. In some of the mixtures it was

I. Axnaes

1976-01-01

102

Elimination of transmissible spongiform encephalopathy infectivity and decontamination of surgical instruments by using radio-frequency gas-plasma treatment.  

PubMed

It has now been established that transmissible spongiform encephalopathy (TSE) infectivity, which is highly resistant to conventional methods of deactivation, can be transmitted iatrogenically by contaminated stainless steel. It is important that new methods are evaluated for effective removal of protein residues from surgical instruments. Here, radio-frequency (RF) gas-plasma treatment was investigated as a method of removing both the protein debris and TSE infectivity. Stainless-steel spheres contaminated with the 263K strain of scrapie and a variety of used surgical instruments, which had been cleaned by a hospital sterile-services department, were examined both before and after treatment by RF gas plasma, using scanning electron microscopy and energy-dispersive X-ray spectroscopic analysis. Transmission of scrapie from the contaminated spheres was examined in hamsters by the peripheral route of infection. RF gas-plasma treatment effectively removed residual organic residues on reprocessed surgical instruments and gross contamination both from orthopaedic blades and from the experimentally contaminated spheres. In vivo testing showed that RF gas-plasma treatment of scrapie-infected spheres eliminated transmission of infectivity. The infectivity of the TSE agent adsorbed on metal spheres could be removed effectively by gas-plasma cleaning with argon/oxygen mixtures. This treatment can effectively remove 'stubborn' residual contamination on surgical instruments. PMID:16033987

Baxter, H C; Campbell, G A; Whittaker, A G; Jones, A C; Aitken, A; Simpson, A H; Casey, M; Bountiff, L; Gibbard, L; Baxter, R L

2005-08-01

103

Sterilization effects on starPEG coated polymer surfaces: characterization and cell viability  

Microsoft Academic Search

Sterilization is frequently an issue for polymeric biomaterials including hydrogels, where autoclaving needs to be discarded,\\u000a and ?-irradiation and low temperature hydrogen peroxide gas plasma sterilization are already important alternatives. Coatings\\u000a based on poly(ethylene glycol) are a well-known strategy to reduce unspecific protein interactions on biomaterial surfaces.\\u000a Dense, ultrathin coatings of isocyanate terminated star-shaped poly(ethylene glycol) (starPEG) molecules have proven

Júlia Lleixà Calvet; Dirk Grafahrend; Doris Klee; Martin Möller

2008-01-01

104

Ideal gas behavior of a strongly coupled complex (dusty) plasma.  

PubMed

In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas. PMID:23863006

Oxtoby, Neil P; Griffith, Elias J; Durniak, Céline; Ralph, Jason F; Samsonov, Dmitry

2013-07-01

105

Is gas-discharge plasma a new solution to the old problem of biofilm inactivation?  

PubMed

Conventional disinfection and sterilization methods are often ineffective with biofilms, which are ubiquitous, hard-to-destroy microbial communities embedded in a matrix mostly composed of exopolysaccharides. The use of gas-discharge plasmas represents an alternative method, since plasmas contain a mixture of charged particles, chemically reactive species and UV radiation, whose decontamination potential for free-living, planktonic micro-organisms is well established. In this study, biofilms were produced using Chromobacterium violaceum, a Gram-negative bacterium present in soil and water and used in this study as a model organism. Biofilms were subjected to an atmospheric pressure plasma jet for different exposure times. Our results show that 99.6 % of culturable cells are inactivated after a 5 min treatment. The survivor curve shows double-slope kinetics with a rapid initial decline in c.f.u. ml(-1) followed by a much slower decline with D values that are longer than those for the inactivation of planktonic organisms, suggesting a more complex inactivation mechanism for biofilms. DNA and ATP determinations together with atomic force microscopy and fluorescence microscopy show that non-culturable cells are still alive after short plasma exposure times. These results indicate the potential of plasma for biofilm inactivation and suggest that cells go through a sequential set of physiological and morphological changes before inactivation. PMID:19246743

Joaquin, Jonathan C; Kwan, Calvin; Abramzon, Nina; Vandervoort, Kurt; Brelles-Mariño, Graciela

2009-03-01

106

Partial microwave-assisted wet digestion of animal tissue using a baby-bottle sterilizer for analyte determination by inductively coupled plasma optical emission spectrometry  

NASA Astrophysics Data System (ADS)

A procedure for partial digestion of bovine tissue is proposed using polytetrafluoroethylene (PTFE) micro-vessels inside a baby-bottle sterilizer under microwave radiation for multi-element determination by inductively coupled plasma optical emission spectrometry (ICP OES). Samples were directly weighed in laboratory-made polytetrafluoroethylene vessels. Nitric acid and hydrogen peroxide were added to the uncovered vessels, which were positioned inside the baby-bottle sterilizer, containing 500 mL of water. The hydrogen peroxide volume was fixed at 100 µL. The system was placed in a domestic microwave oven and partial digestion was carried out for the determination of Ca, Cu, Fe, Mg, Mn and Zn by inductively coupled plasma optical emission spectrometry. The single-vessel approach was used in the entire procedure, to minimize contamination in trace analysis. Better recoveries and lower residual carbon content (RCC) levels were obtained under the conditions established through a 2 4-1 fractional factorial design: 650 W microwave power, 7 min digestion time, 50 µL nitric acid and 50 mg sample mass. The digestion efficiency was ascertained according to the residual carbon content determined by inductively coupled plasma optical emission spectrometry. The accuracy of the proposed procedure was checked against two certified reference materials.

Matos, Wladiana O.; Menezes, Eveline A.; Gonzalez, Mário H.; Costa, Letícia M.; Trevizan, Lilian C.; Nogueira, Ana Rita A.

2009-06-01

107

Numerical modeling for a better understanding of gas discharge plasmas  

Microsoft Academic Search

We present here some of our modeling efforts for gas discharge plasmas, used in a number of applications in materials science. Different kinds of modeling approaches are applied, including fluid models, particle-in-cell - Monte Carlo (PIC-MC) models and hybrid Monte Carlo - fluid models, for the plasma behavior, as well as molecular dynamics simulations for thin film growth. The application

Annemie Bogaerts; Kathleen De Bleecker; Violeta Georgieva; Dieter Herrebout; Ivan Kolev; Myriam Madani; Erik Neyts

2005-01-01

108

Termination of a Magnetized Plasma on a Neutral Gas: The End of the Plasma  

NASA Astrophysics Data System (ADS)

Experiments are performed at the Enormous Toroidal Plasma Device at UCLA to study the neutral boundary layer (NBL) between a magnetized plasma and a neutral gas along the direction of a confining magnetic field. This is the first experiment to measure plasma termination within a neutral gas without the presence of a wall or obstacle. A magnetized, current-free helium plasma created by a lanthanum hexaboride (LaB6) cathode terminates entirely within a neutral helium gas. The plasma is weakly ionized (ne/nn˜1%) and collisional ?n?Lplasma. The NBL occurs where the plasma pressure equilibrates with the neutral gas pressure, consistent with a pressure balance model. It is characterized by a field-aligned ambipolar electric field, developing self-consistently to maintain a current-free termination of the plasma on the neutral gas. Probes are inserted into the plasma to measure the plasma density, flow, temperature, current, and potential. These measurements confirm the presence of the ambipolar field and the pressure equilibration model of the NBL.

Cooper, C. M.; Gekelman, W.

2013-06-01

109

21 CFR 610.12 - Sterility.  

Code of Federal Regulations, 2013 CFR

...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....

2013-04-01

110

Synthesis gas production from peat using a steam plasma  

Microsoft Academic Search

A steam plasma was used to convert peat into a synthesis gas, suitable for methanol production, in a cocurrent transport reactor. A cylindrical stainless-steel reactor 20 cm in diameter and 120 cm long was used. The effects of temperature and the carbon\\/ steam molar ratio on the product gas composition and carbon conversion were investigated. Finely ground peat (mean particle

P. R. Stuart; R. J. Munz; W. H. Gauvin

1984-01-01

111

[What should be the length and inner diameter of the testing device for microbiological efficacy testing of formaldehyde gas sterilization methods?].  

PubMed

The series of tests described in a preceding publication (Spicher and Borchers, 1983) has been continued in a modified way. This time, the dependency of the microbiological test results of a formaldehyde gas sterilization procedure on length and inner diameter of the tubes serving as test pieces was examined. The tubes were 1 or 2 m in length with an inner diameter of 1 or 2 mm. The tests were performed with four different preparations of bioindicators. Spores of Bac. stearothermophilus served as test germs. The preparations differed in the type of suspension used for the preparation of the bioindicators: distilled water, diluted blood (10%), undiluted blood, 10% albumin solution. The spore suspensions had been dried on linen thread. During the test procedure, the bioindicators were located near the sealed end of the tube. After completion of the sterilization procedure, the bioindicators were examined for viable germs. In tubes of identical length, the frequency of indicators carrying viable germs was always higher in those of 1 mm than in those of 2 mm inner diameter. In tubes of identical inner diameter, the frequency of indicators carrying viable germs in those of 2 m length was always higher than in those of 1 m length. This regularity was independent of the type of bioindicators used. The bioindicators for the preparation of which a 10% albumin solution had been employed showed the highest resistance. A somewhat lower resistance was found for the bioindicators prepared with undiluted blood. The bioindicators for which the spores had been suspended in diluted blood proved to have the lowest resistance. If the spores had been suspended in distilled water, the resistance of the bioindicators was a little lower than that of those suspended in undiluted blood, but was higher than that of the dried spores with diluted blood. The test results confirm the effectiveness of the method proposed earlier, i.e. to deposit the bioindicators in special test pieces (e.g. tubes or sounds) for the microbiological testing of formaldehyde gas sterilization procedures. These test pieces must be at least as long and as narrow as the longest and narrowest cavity of the object to be sterilized (tubes, catheters). In order to standardize the microbiological testing of formaldehyde gas sterilization procedures and to guarantee a certain minimum efficiency, the bioindicator as well as the test piece and its size (length and inner diameter) should be standardized.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6524142

Spicher, G; Borchers, U

1984-10-01

112

Synergistic sterilization effect of microwave-excited nonthermal Ar plasma, H2O2, H2O and TiO2, and a global modeling of the interactions  

NASA Astrophysics Data System (ADS)

A microwave-excited atmospheric-pressure plasma jet (uAPPJ) exhibited a synergistic sterilization effect when combined with hydrogen peroxide (H2O2), distilled water (DW) and titanium dioxide (TiO2) photocatalysis. The sterilization efficacy of H2O2-uAPPJ increased as the H2O2 concentration increased. The addition of TiO2 also remarkably increased the sterilization efficacy. To find the main factor for the sterilization effect, optical emission spectra and the degradation rate of a methylene blue solution were measured. Numerical analysis, a newly developed global modeling, was also conducted to discover the mechanisms. Both experimental measurements and global modeling results suggested that combinations of H2O2, DW and TiO2 increased the generation of hydroxyl radicals (·OH), which are known to be strong bactericidal agents. It was revealed that charged species, especially electrons, have a dominant role in the increase of ·OH.

Lee, H. Wk; Lee, H. W.; Kang, S. K.; Y Kim, H.; Won, I. H.; Jeon, S. M.; Lee, J. K.

2013-10-01

113

Prospects for Treating Foods with Cold Atmospheric Gas Plasmas  

NASA Astrophysics Data System (ADS)

In this review the potential applications of cold atmospheric gas plasmas are presented with particular reference to the problems of contamination of foods by biological agents. In addition to the accidental contamination of food, the very real threat arising from the deliberate contamination of the human food chain is also considered. The evidence that has been gained for the efficacy of cold plasmas in inactivating a wide range of biological agents is briefly surveyed. This is followed by an examination of previous work in which ­various types of foodstuffs have been successfully treated using cold gas plasmas. The need to demonstrate that the quality attributes of treated foods is not adversely affected is stressed. Finally, the role which gas plasmas may have in decontaminating food processing equipment is considered.

Shama, Gilbert; Kong, Michael G.

114

Puff-gas coaxial-injected electromagnetic coaxial plasma gun  

Microsoft Academic Search

The design, construction, and testing of a pulsed gas-injection coaxial plasma gun driven by a 72-microF capacitor bank, with operating voltages of 60-80 kV (stored energy 130-230 kJ) and 1.6-MA, 1-microsec-rise-time current discharges. Using deuterium gas, reliable delivery of all current to the gas and neutron yields of greater than 10 to the 9th are obtained. Current, voltage, inductance, and

J. H. Degnan; W. L. Baker; S. W. R. Warren; D. W. Price; M. P. Snell

1987-01-01

115

Puff-gas coaxial-injected electromagnetic coaxial plasma gun  

Microsoft Academic Search

We have designed, built, and tested a pulsed gas-injection coaxial plasma gun driven by a 72-?F capacitor bank, with operating voltages of 60–80 kV (stored energy 130–230 kJ), and 1.6-MA, 1-?s rise-time current discharges. Using deuterium gas, we have obtained reliable delivery of all current to the gas and neutron yields of greater than 109. Current, voltage, inductance, and current

J. H. Degnan; W. L. Baker; S. W. R. Warren; D. W. Price; M. P. Snell; R. J. Richter-Sand; P. J. Turchi

1987-01-01

116

Supersonic gas injector for plasma fueling  

Microsoft Academic Search

A supersonic gas injector (SGI) has been developed for fueling and diagnostic applications on the National Spherical Torus Experiment (NSTX). It is comprised of a graphite converging-diverging Laval nozzle and a commercial piezoelectric gas valve mounted on a movable probe at a low field side midplane port location. Also mounted on the probe is a diagnostic package: a Langmuir probe,

V. A. Soukhanovskii; H. W. Kugel; R. Kaita; A. L. Roquemore; M. Bell; W. Blanchard; C. Bush; R. Gernhardt; G. Gettelfinger; T. Gray; R. Majeski; J. Menard; T. Provost; P. Sichta; R. Raman

2005-01-01

117

Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode  

SciTech Connect

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

A. Dunaevsky; N.J. Fisch

2004-03-08

118

Microwave Plasma Sources for Gas Processing  

SciTech Connect

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.

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

2008-03-19

119

Emission spectroscopic study on gas-gas interactions in glow discharge plasmas using several binary gas mixtures.  

PubMed

Emission spectra of constituent gas species from glow discharge plasmas using argon-helium, krypton-helium, argon-krypton, and krypton-argon gas mixtures were analyzed to elucidate collisional energy transfer between these gas species occurring in the plasma. In the argon-helium mixed gas plasma, the enhancement or quenching of particular Ar II lines was observed when helium was added to an argon-matrix glow discharge plasma, meaning that a redistribution in the population among the excited levels could be induced through argon-helium collisions. On the other hand, the krypton-helium plasma showed little change in the emission intensities of Kr II lines when helium was added to a krypton-matrix glow discharge plasma, meaning that energy exchanges between krypton and helium excited species occur inactively. These phenomena are principally because the excitation energy as well as the spin multiplicity between collision partners follow both the energy resonance conditions and the spin conservation rule in collisions of the second kind in the argon-helium system, but not in the krypton-helium system. In the argon-krypton and krypton-argon mixed gas plasmas, significant intensity changes of particular Ar II or Kr II lines could not be found; therefore, there were no dominant channels for energy exchanges between argon and krypton species in the mixed gas plasmas. PMID:20215678

Wagatsuma, Kazuaki

2010-01-01

120

Female sterilization.  

PubMed

There has been considerable development and implementation of new contraceptive methods over the last 15 years. However, sterilization has remained the most widely used method around the world. Ideally, the procedure should be safe, have a high efficacy, be readily accessible, and be personally and culturally acceptable. The cost for each procedure would be low and the method would be simple, quick, easily learned and be able to be performed in an outpatient setting without general anesthesia. A transuterine method of female sterilization has long been the ideal for the gynecologist. The Essure system fulfils many of the criteria, and is the first one to be approved by the US FDA. However, there is still a need for further research to find a device with the success rate of the Essure but without its irreversibility. PMID:18573050

Chapman, Lynne; Magos, Adam

2008-07-01

121

Calculation of Ion Energy Distribution Functions at the Inner Surface of a Pet Bottle During Sterilization Processes  

NASA Astrophysics Data System (ADS)

Due to a growing demand for bottles made of polyethylene terephthalate (PET) fast and efficient sterilization processes as well as barrier coating to decrease gas permeation are required. Plasma sterilization is an alternative way of sterilizing PET without using toxic ingredients (e.g. hydrogen peroxide or peracetic acid). To allow investigations in the field of plasma sterilization of PET bottles, a microwave plasma reactor has been developed. A coaxial waveguide combined with a gas-inlet, a modified plasmaline, is used for both coupling the microwave power and injecting the gas mixture into the bottle. One key parameter in the context of plasma treatment of bottles is the ion energy distribution function (IEDF) at the inner surface of the bottle. Additional it is possible to apply a DC bias potential to a metal cage which is placed around the bottle. Numerical results for IEDFs performed by means of the Hybrid Plasma Equipment Model (HPEM) are presented. Plasmas with relevant gas mixtures (Ar and ArO2) at different pressures and input powers are examined. The numerical results are compared with experimentally obtained data and show very good agreement.

Szeremley, Daniel; Steves, Simon; Brinkmann, Ralf Peter; Awakowicz, Peter; Kushner, Mark J.; Mussenbrock, Thomas

2012-10-01

122

Nanocluster ion source by plasma-gas aggregation  

NASA Astrophysics Data System (ADS)

We are constructing and developing a new type cluster ion source and a detection system. The new cluster ion source consists of a large area plasma source and gas aggregation cell instead of present cluster ion source configuration (magnetron ion source and gas aggregation cell). In new type cluster ion source we adopted a pulsed high-power microwave type plasma source for production of ions and neutral particles. This source can produce dense and stable plasma independent of shape or properties of the sample, and additionally it can produce large sizes of plasma, so that whole area of the sample is sputtered. This feature allows us to produce an intense beam of cluster ions stably compared to the present ion source.

Imanaka, Masashi; Katayama, Takeshi; Ohshiro, Yukimitsu; Watanabe, Shin-Ichi; Arai, Hideyuki; Nakagawa, Takahide

2004-05-01

123

Anode attachment of torch plasma arc with high-speed lateral gas air and axial plasma gas argon  

NASA Astrophysics Data System (ADS)

Torch plasma arcs have useful high-energy and high-current characteristics. Torch plasma arcs can be flexible even if exposed to high-speed laterally flowing gases. This study measured the length, voltage, input power, heat power and heat efficiency of a torch plasma arc to the anode to elucidate their influence upon the plasma torch arc anode attachment with a high-velocity laterally flowing gas. That velocity was varied from 0 to 60 m s-1. The axial plasma gas argon flow rates used were 4, 8 and 12 slpm. Consequently, the input power increased about 8000-16 000 W with these lateral gas air velocities. The heat efficiency decreased with lateral gas air velocity from about 50% to 25% at a current of I = 150 A. The torch plasma arc length, La, was ca 1 cm. The results of this study are applicable for providing electrical power from the ground to high-speed vehicles or vice versa and for reducing anode erosion by anode spot movement.

Iwao, Toru; Beppu, Takuya; Ishikawa, Shuhei; Inaba, Tsuginori

2004-04-01

124

Emission continua of rare gas plasmas  

Microsoft Academic Search

Photoionization cross sections of rare gases have been calculated by using the scaled Thomas-Fermi method, including polarization effects. Absorption coefficients have been derived for bound-free transitions in thermal plasmas of 6000 K to 30,000 K, for a wavelength range from 300 A to 10,000 A.

D. Hofsaess

1978-01-01

125

A CC-SAM, for coiled coil-sterile ? motif, domain targets the scaffold KSR-1 to specific sites in the plasma membrane.  

PubMed

Kinase suppressor of Ras-1 (KSR-1) is an essential scaffolding protein that coordinates the assembly of the mitogen-activated protein kinase (MAPK) module, consisting of the MAPK kinase kinase Raf, the MAPK kinase MEK (mitogen-activated or extracellular signal-regulated protein kinase kinase), and the MAPK ERK (extracellular signal-regulated kinase) to facilitate activation of MEK and thus ERK. Although KSR-1 is targeted to the cell membrane in part by its atypical C1 domain, which binds to phospholipids, other domains may be involved. We identified another domain in KSR-1 that we termed CC-SAM, which is composed of a coiled coil (CC) and a sterile ? motif (SAM). The CC-SAM domain targeted KSR-1 to specific signaling sites at the plasma membrane in growth factor-treated cells, and it bound directly to various micelles and bicelles in vitro, indicating that the CC-SAM functioned as a membrane-binding module. By combining nuclear magnetic resonance spectroscopy and experiments in cultured cells, we found that membrane binding was mediated by helix ?3 of the CC motif and that mutating residues in ?3 abolished targeting of KSR-1 to the plasma membrane. Thus, in addition to the atypical C1 domain, the CC-SAM domain is required to target KSR-1 to the plasma membrane. PMID:23250398

Koveal, Dorothy; Schuh-Nuhfer, Natasha; Ritt, Daniel; Page, Rebecca; Morrison, Deborah K; Peti, Wolfgang

2012-12-18

126

Strong drive compression of a gas-cooled positron plasma  

SciTech Connect

The use of rotating electric fields to control plasmas has found numerous applications in the manipulation and storage of antimatter. When used in strong magnetic fields plasma heating caused by the applied field is mitigated by cyclotron cooling, leading to an efficient broadband mode of compression known as the strong drive regime. We have found that it is possible to access the strong drive regime in a low field trap where cyclotron cooling is negligible and a gas is used for cooling, and we have been able to compress positron plasmas to more than 10% of the Brillouin density limit.

Cassidy, D. B.; Mills, A. P. Jr. [Department of Physics and Astronomy, University of California, Riverside, California 92521-0413 (United States); Greaves, R. G. [First Point Scientific, Inc., 5330 Derry Avenue, Suite J, Agoura Hills, California 91301 (United States); Meligne, V. E. [Department of Physics and Astronomy, University of California, Riverside, California 92521-0413 (United States); First Point Scientific, Inc., 5330 Derry Avenue, Suite J, Agoura Hills, California 91301 (United States)

2010-03-08

127

Determination of phenytoin in human plasma by gas chromatography.  

PubMed

A gas chromatographic method for the determination of phenytoin in plasma is described. This assay allows the determination of phenytoin for therapeutic drug monitoring with a minimum detectable limit of 200 ngmL-1 for 500 mL plasma. Separation was performed on 2 m x 2 mm i.d. 1.5% OV17, 1.95 OV210 packed column using a flame-ionization detector. Barbital and tetramethyl ammonium hydroxide were used as internal standard and derivatizing agent, respectively. This method is simple, rapid and suitable for routine analysis of phenytoin in plasma. PMID:10765466

Zarghi, A; Gholami, K; Hessami, M

1999-11-01

128

Gas laser with dual plasma mixing  

DOEpatents

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.

Pinnaduwage, L.A.

1999-04-06

129

Gas laser with dual plasma mixing  

DOEpatents

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.

Pinnaduwage, Lal A. (Knoxville, TN)

1999-01-01

130

Photoresist Ashing Process Using Carbon Tetrafluoride Gas Plasma with Ammonia Gas Addition  

NASA Astrophysics Data System (ADS)

A low-damage photoresist ashing process was developed for the fabrication of thin-film transistor liquid-crystal displays (TFT-LCDs). This process utilizes a downflow plasma using a carbon tetrafluoride/oxygen (CF4/O2) gas mixture at room temperature. Although this process simultaneously achieves a high ashing rate and a low etching rate for an underlying amorphous silicon (a-Si:H) film containing hydrogen (H), contact resistance increases. We achieved contact resistances of less than 2 k? by the addition of ammonia (NH3) gas into the CF4/O2 gas mixture plasma. The ratio of reactive fluorine radicals (F) to argon atoms (Ar) decreased with increasing NH3 gas flow rate and became less than 0.7 at the NH3 gas flow rate higher than 15 sccm. Reaction products formed on a-Si:H films by the addition of NH3 gas to the CF4/O2 gas mixture plasma obstructed the etching of the a-Si:H films by F@. On the basis of plasma analysis results for the CF4/O2/NH3 gas mixture, a possible mechanism for low damage to a-Si:H films was proposed.

Saito, Makoto; Eto, Hideo; Omiya, Kayoko; Homma, Tetsuya; Nagatomo, Takao

2001-07-01

131

Modeling Study of Asymmetric Plasma Properties Produced by Pumping and Gas Injection in Inductively Coupled Plasmas  

NASA Astrophysics Data System (ADS)

The trend towards operating with lower gas pressures for plasma processing is partly motivated by the desire to operate in a "diffusive" environment with the goal of obtaining more uniform reactant fluxes to the substrate. Based on the premise that reactant transport is dominantly diffusive, low pressure, high plasma density reactors often use azimuthally asymmetric gas injection and pumping. In this paper, the consequences of asymmetric gas injection and pumping on the uniformity of reactant fluxes in inductively coupled plasma reactors are computationally investigated using a 3-dimensional plasma equipment model. Cl2 and Ar/SiH4 gas mixtures are studied as examples of etching and deposition systems while injecting gas from discrete nozzles with side or symmetrical pumping. We found that under nominal operating conditions (10 mTorr, 400 W, 150 sccm) fluxes of ions to the wafer are little affected by asymmetric gas injection and pumping due to the dominance of ambipolar transport. Reactant fluxes to the substrate, such as Cl, can display significant asymmetries, which worsen with increasing pressure and increasing reactive sticking coefficient.

Keiter, Eric; Kushner, Mark J.

1997-10-01

132

Wound healing modeling: investigating ambient gas plasma treatment efficacy  

NASA Astrophysics Data System (ADS)

Chronic wounds are thought to be caused, in part, by the presence and persistence of aerobic microbes that deplete the local oxygen concentration and prevent or slow the rate of oxygen-dependent healing. Atmospheric-pressure gas plasmas have been shown to be strong bactericidal agents and there is evidence that plasma treatment can safely kill bacteria in wounds and speed wound healing. In this study, we adapted a six-species reaction-diffusion model of epithelial wound healing and used it to predict the efficacy of various plasma treatment protocols. We assume that the only effect of plasma application to the wound is to reduce the bacterial load and that this in turn reduces the bacterial oxygen consumption in the wound. The model follows the spatial and temporal concentration or density profiles within the wound of oxygen, chemoattractants, capillary sprouts, blood vessels, fibroblasts and extracellular matrix material. We highlight the importance of the effects of plasma application on the rate of bacterial regrowth in the wound. Even a relatively large initial reduction in the bacterial wound population may not be sufficient for improved healing if bacterial regrowth is not limited. Although it is clear that current efforts to model wound healing in general and the effects of plasma in particular are in their early stage, the present results suggest several important directions for coupling plasma models with models of tissue biochemical responses.

Orazov, Marat; Sakiyama, Yukinori; Graves, David B.

2012-11-01

133

Treatment of CO 2 gas by high-energy type plasma  

Microsoft Academic Search

As one of the applications of high-energy type plasma to environmental problems, the treatment of carbon dioxide gas was studied, and the fundamental experiment was carried out by using a gas tunnel type plasma jet. In this paper, the results about the electrical characteristics of plasma torch and the thermal efficiency are shown. The thermal efficiency of the plasma torch

A. Kobayashi; K. Osaki; C. Yamabe

2002-01-01

134

Dynamic gas flow during plasma operation in TMX-U  

SciTech Connect

Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73/sup 0/ Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation.

Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

1982-11-12

135

Plasma formation inside deformed gas bubbles submerged in water  

NASA Astrophysics Data System (ADS)

Plasma formation in liquids produces highly reactive products that may be desirable for a variety of applications, including water purification and waste processing. The direct ignition of plasma in these environments, however, is limited by the large breakdown strength of liquids, which imposes severe voltage and energy requirements on the design of practical devices. One way to address this issue is by first igniting plasma in gas bubbles injected into the water. These bubbles provide an environment with higher reduced electric field (E/N) that is more suitable for plasma formation. If the same bubbles can be excited into strong distortions of their shape and volume, then it is possible to further alter E/N, both by field enhancement at the bubble's highly distorted dielectric interface (via E) and by fluctuations in its internal gas pressure (via N). This principle is investigated by trapping a single bubble at the node of a 26.4 kHz underwater acoustic field and driving it into violent oscillations using an A.C electric field. A third high voltage needle is placed nearby and used to ignite plasma in the bubble at various points during its oscillation. The bubble response is captured using a high speed camera capable of up to 30,000 frames per second.

Sommers, Bradley; Foster, John

2012-10-01

136

Plasma remediation of gas streams contaminated by trichloroethylene  

SciTech Connect

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.

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

137

Puff-gas coaxial-injected electromagnetic coaxial plasma gun  

NASA Astrophysics Data System (ADS)

The design, construction, and testing of a pulsed gas-injection coaxial plasma gun driven by a 72-microF capacitor bank, with operating voltages of 60-80 kV (stored energy 130-230 kJ) and 1.6-MA, 1-microsec-rise-time current discharges. Using deuterium gas, reliable delivery of all current to the gas and neutron yields of greater than 10 to the 9th are obtained. Current, voltage, inductance, and current position data are discussed and are compared with circuit-solver models. Magnetic-probe and filtered scintillator/photomultiplier detector-array data on high-energy photon spectra were taken. A second puff-gas valve near the anode (inner electrode) axis at the muzzle end substantially improved the neutron yield.

Degnan, J. H.; Baker, W. L.; Warren, S. W. R.; Price, D. W.; Snell, M. P.

1987-04-01

138

Gas flow driven by thermal creep in dusty plasma  

SciTech Connect

Thermal creep flow (TCF) is a flow of gas driven by a temperature gradient along a solid boundary. Here, TCF is demonstrated experimentally in a dusty plasma. Stripes on a glass box are heated by laser beam absorption, leading to both TCF and a thermophoretic force. The design of the experiment allows isolating the effect of TCF. A stirring motion of the dust particle suspension is observed. By eliminating all other explanations for this motion, we conclude that TCF at the boundary couples by drag to the bulk gas, causing the bulk gas to flow, thereby stirring the suspension of dust particles. This result provides an experimental verification, for the field of fluid mechanics, that TCF in the slip-flow regime causes steady-state gas flow in a confined volume.

Flanagan, T. M.; Goree, J. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

2009-10-15

139

Fast Gas Replacement in Plasma Process Chamber by Improving Gas Flow Pattern  

NASA Astrophysics Data System (ADS)

The precise and high-speed alteration of various gas species is important for realizing precise and well-controlled multiprocesses in a single plasma process chamber with high throughput. The gas replacement times in the replacement of N2 by Ar and that of H2 by Ar are measured in a microwave excited high-density and low electron-temperature plasma process chamber at various working pressures and gas flow rates, incorporating a new gas flow control system, which can avoid overshoot of the gas pressure in the chamber immediately after the valve operation, and a gradational lead screw booster pump, which can maintain excellent pumping capability for various gas species including lightweight gases such as H2 in a wide pressure region from 10-1 to 104 Pa. Furthermore, to control the gas flow pattern in the chamber, upper ceramic shower plates, which have thousands of very fine gas injection holes (numbers of 1200 and 2400) formed with optimized allocation on the plates, are adopted, while the conventional gas supply method in the microwave-excited plasma chamber uses many holes only opened at the sidewall of the chamber (gas ring). It has been confirmed that, in the replacement of N2 by Ar, a short replacement time of approximately 1 s in the cases of 133 and 13.3 Pa and approximately 3 s in the case of 4 Pa can be achieved when the upper shower plate has 2400 holes, while a replacement time longer than approximately 10 s is required for all pressure cases where the gas ring is used. In addition, thanks to the excellent pumping capability of the gradational lead screw booster pump for lightweight gases, it has also been confirmed that the replacement time of H2 by Ar is almost the same as that of N2 by Ar.

Morishita, Sadaharu; Goto, Tetsuya; Akutsu, Isao; Ohyama, Kenji; Ito, Takashi; Ohmi, Tadahiro

2009-01-01

140

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

NASA Astrophysics Data System (ADS)

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.

Hong, Yong Cheol; Park, Hyun Jae; Lee, Bong Ju; Kang, Won-Seok; Uhm, Han Sup

2010-05-01

141

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

NASA Astrophysics Data System (ADS)

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.

Cooper, Christopher Michael

142

Theoretical Study of sputtered Material Redeposition on the Target in Alternating Current Gas Discharge Plasma  

Microsoft Academic Search

Sputtering of solid surfaces by plasma ions in the alternating current (AC) gas discharge takes place in many devices such as gas-discharge displays, plasma etching systems, arc discharge lamps etc. At relatively high background gas pressures the sputtered atoms collide with gas atoms in the vicinity of the surface and then move in the diffusion mode. As a result, some

Guennadi Bondarenko; Olga Bonk; Vladimir Kristya

2000-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

144

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

SciTech Connect

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

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

2012-07-01

145

Ultra-Intense Laser Pulse Propagation in Gas and Plasma  

SciTech Connect

It is proposed here to continue their program in the development of theories and models capable of describing the varied phenomena expected to influence the propagation of ultra-intense, ultra-short laser pulses with particular emphasis on guided propagation. This program builds upon expertise already developed over the years through collaborations with the NSF funded experimental effort lead by Professor Howard Milchberg here at Maryland, and in addition the research group at the Ecole Polytechnique in France. As in the past, close coupling between theory and experiment will continue. The main effort of the proposed research will center on the development of computational models and analytic theories of intense laser pulse propagation and guiding structures. In particular, they will use their simulation code WAKE to study propagation in plasma channels, in dielectric capillaries and in gases where self focusing is important. At present this code simulates the two-dimensional propagation (radial coordinate, axial coordinate and time) of short pulses in gas/plasma media. The plasma is treated either as an ensemble of particles which respond to the ponderomotive force of the laser and the self consistent electric and magnetic fields created in the wake of pulse or as a fluid. the plasma particle motion is treated kinetically and relativistically allowing for study of intense pulses that result in complete cavitation of the plasma. The gas is treated as a nonlinear medium with rate equations describing the various stages of ionization. A number of important physics issues will be addressed during the program. These include (1) studies of propagation in plasma channels, (2) investigation of plasma channel nonuniformities caused by parametric excitation of channel modes, (3) propagation in dielectric capillaries including harmonic generation and ionization scattering, (4) self guided propagation in gas, (5) studies of the ionization scattering instability recently identified theoretically and experimentally in the group, and (6) studies of propagation in cluster plasmas. New models will be developed for the harmonic generation of radiation and these will be incorporated in the modeling and simulation.

Antonsen, T. M.

2004-10-26

146

Temperature Gradient Effects on the Neutral Gas Penetration into a Magnetized Plasma.  

National Technical Information Service (NTIS)

The experimental evidence of temperature gradient effects on the neutral gas penetration into plasma is presented. It is found that an increased temperature gradient reduces the neutral gas content in the partially ionized boundary layer of a cold gas bla...

M. Bures

1982-01-01

147

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

SciTech Connect

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.

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

2009-05-02

148

Spectroscopic analysis of the plasma created by a double-flux tungsten inert gas (TIG) arc plasma torch  

Microsoft Academic Search

Measurements of population densities and temperature distributions have been performed in a double-flux tungsten inert gas (TIG) arc plasma column using high-resolution spectroscopy. The experimental conditions have been chosen to mimic typical welding conditions with argon gas. The results show that the plasma is dominated by metallic vapour species in the vicinity of the molten anode, while a nearly pure

D. Degout; A. Catherinot

1986-01-01

149

Determination of Compounds Inhibiting Bacterial Growth in Sterilized Medical Devices  

Microsoft Academic Search

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

H. Shintani; E. Suzuki; M. Sakurai

2003-01-01

150

Paraformaldehyde for Surface Sterilization and Detoxification.  

National Technical Information Service (NTIS)

Paraformaldehyde powder, depolymerized by heat, produced formaldehyde gas that was effective in sterilizing laboratory rooms, a mobile laboratory trailer, various surfaces, fiberglass filter medium, and specialized laboratory equipment. A sporulating and ...

L. A. Taylor M. S. Barbeito G. G. Gremillion

1969-01-01

151

Process for reducing emissions from industrial sterilizers  

SciTech Connect

This paper describes a process for treating a gas mixture including a sterilant gas and a diluent gas. It comprises: feeding the gas mixture to a first separation process to substantially remove the sterilant from the gas mixture; withdrawing a treated gas stream from the first separation process; feeding the treated gas stream to a second separation process, comprising passing at least a portion of the treated gas stream through a membrane separation unit containing a permselective membrane; withdrawing from the separation unit a first stream enriched in the diluent gas compared with the gas mixture; withdrawing from the membrane separation process a second stream depleted in the diluent gas compared with the gas mixture.

Baker, R.W.; Wijmans, J.G.

1991-12-03

152

Atomic Force Microscope Investigations of Biofilm-Forming Bacterial Cells Treated with Gas Discharge Plasmas  

Microsoft Academic Search

We present investigations of biofilm-forming bacteria before and after treatment from gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve bacteria in biofilm communities, where cooperative interactions between cells make organisms less susceptible to standard killing methods. Chromobacterium violaceum were imaged before and after plasma

Kurt Vandervoort; Andrew Renshaw; Nina Abramzon; Graciela Brelles-Marino

2009-01-01

153

Instability of dusty particle system in gas-discharge plasma  

SciTech Connect

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.

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

154

Continuous gas discharge plasma with 200 K electron temperature  

NASA Astrophysics Data System (ADS)

A very cold and collisional hot-filament discharge plasma is created in a vacuum chamber with an inner wall cooled by liquid nitrogen. The inner chamber (16.5 cm diameter×30 cm) has two negatively biased tungsten filaments for plasma generation and a Langmuir probe on axis for diagnostic measurements. With the wall at 140 K, 0.5-16 mA filament emission, and 1.6 mTorr carbon monoxide as the working gas, probe data give electron temperatures of 17-28 meV (197-325 K) with corresponding densities of 108-109 cm-3. With He, Ar, H2, and N2 at 140 K, the electron temperatures are >500 K. The lower electron temperature with CO is attributed to the asymmetric CO molecule having a larger cross section for electron excitation of rotational modes as a consequence of its dipole moment.

Dickson, Shannon; Robertson, Scott

2010-03-01

155

Continuous gas discharge plasma with 200 K electron temperature  

SciTech Connect

A very cold and collisional hot-filament discharge plasma is created in a vacuum chamber with an inner wall cooled by liquid nitrogen. The inner chamber (16.5 cm diameterx30 cm) has two negatively biased tungsten filaments for plasma generation and a Langmuir probe on axis for diagnostic measurements. With the wall at 140 K, 0.5-16 mA filament emission, and 1.6 mTorr carbon monoxide as the working gas, probe data give electron temperatures of 17-28 meV (197-325 K) with corresponding densities of 10{sup 8}-10{sup 9} cm{sup -3}. With He, Ar, H{sub 2}, and N{sub 2} at 140 K, the electron temperatures are >500 K. The lower electron temperature with CO is attributed to the asymmetric CO molecule having a larger cross section for electron excitation of rotational modes as a consequence of its dipole moment.

Dickson, Shannon; Robertson, Scott [Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States)

2010-03-15

156

Gas chromatography\\/plasma spectrometry—an important analytical tool for elemental speciation studies  

Microsoft Academic Search

In this review, a full discussion and update of the state-of-the-art of gas chromatography (GC) coupled to all known plasma spectrometers is presented. A brief introductive discussion of the advantages and disadvantages of GC–plasma interfaces, as well as types of plasmas and mass spectrometers, is given. The plasma-based techniques covered include inductively coupled plasma mass spectrometry (ICP-MS) microwave-induced plasma optical

Jorgelina C. A Wuilloud; Rodolfo G Wuilloud; Anne P Vonderheide; Joseph A Caruso

2004-01-01

157

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

Microsoft Academic Search

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

O. Batishchev; K. Molvig

2002-01-01

158

Neutral gas density depletion due to neutral gas heating and pressure balance in an inductively coupled plasma  

NASA Astrophysics Data System (ADS)

The spatial distribution of neutral gas temperature and total pressure have been measured for pure N2, He/5%N2 and Ar/5%N2 in an inductively coupled plasma (ICP) reactor, and a significant rise in the neutral gas temperature has been observed. When thermal transpiration is used to correct total pressure measurements, the total pressure remains constant regardless of the plasma condition. Neutral pressure is depleted due to the pressure balance when the plasma pressure (mainly electron pressure) becomes comparable to the neutral pressure in high density plasma. Since the neutral gas follows the ideal gas law, the neutral gas density profile was obtained from the neutral gas temperature and the corrected neutral pressure measurements. The results show that the neutral gas density at the centre of the plasma chamber (factor of 2-4 ×) decreases significantly in the presence of a plasma discharge. Significant spatial variation in neutral gas uniformity occurs in such plasmas due to neutral gas heating and pressure balance.

Shimada, Masashi; Tynan, George R.; Cattolica, Robert

2007-02-01

159

Processing of Films and Fabrics with the MOD-VIII Roll-to-Roll One Atmosphere Uniform Glow Discharge Plasma (OAUGDP®) Reactor  

Microsoft Academic Search

Summary form only given. Industrial atmospheric pressure plasma treatment has unique advantages over vacuum plasma technology for material surface energy enhancement, surface cleaning and decontamination, sterilization, surface etching and related tasks. The MOD-VIII plasma reactor studied in this paper consists of a fabric feed system, a gas feed system, a water cooling system, and a OAUGDPreg plasma reactor. We have

Zhe Chen; Qingquan Li; S. Nourgostar; J. Reece Roth

2007-01-01

160

Experimental and numerical studies of neutral gas depletion in an inductively coupled plasma  

NASA Astrophysics Data System (ADS)

The central theme of this dissertation is to explore the impact of neutral depletion and coupling between plasma and neutral gas in weakly ionized unmagnetized plasma. Since there have been few systematic studies of the mechanism which leads to non-uniform neutral distribution in processing plasmas, this work investigated the spatial profiles of neutral temperature and pressure experimentally, and the mechanism of resulting neutral depletion by simulation. The experimental work is comprised of neutral temperature measurements using high resolution atomic spectroscopy and molecular spectroscopy, and neutral pressure measurements considering thermal transpiration. When thermal transpiration effects are used to correct the gas pressure measurements, the total pressure remains constant regardless of the plasma condition. Since the neutral gas follows the ideal gas law, the neutral gas density profile is also obtained from the measured neutral gas temperature and the corrected pressure measurements. The results show that neutral gas temperature rises close to ˜ 900 [K], and the neutral gas density at the center of plasma chamber has a significant (factor of 2-4x) decrease in the presence of a plasma discharge. In numerical work, neutral and ion transport phenomena were simulated by a hybrid-type direct simulation Monte Carlo (DSMC) method of one dimensional (1D) electrostatic plasma to identify the mechanism of the neutral gas density depletion in Ar/N2 mixtures. The simulation reveals that the neutral depletion is the result of the interplay between plasma and neutral gas, and a parametric study indicates that neutral depletion occurs mainly due to gas heating and pressure balance for the typical condition of plasma processing. In high density plasma sources (Te ? 2-5 eV, ne ? 1011-1012 cm-3) where the plasma pressure becomes comparable to neutral pressure, total pressure (neutral pressure and plasma pressure) is conserved before and after the discharge. Therefore the neutral pressure is reduced due the balance of total pressure with plasma pressure (mainly electron pressure). Neutral gas heating is due to the elastic scattering and charge exchange collisions with ions, which are accelerated by the bulk plasma ambi-polar electrostatic field. The excellent agreement between experiment and simulation, and parametric study reveal that gas heating and pressure balance are the main mechanisms of gas depletion in an inductively coupled plasma. Coupling between plasma and neutral gas was observed by both experiment and simulation. The resulting gas depletion enhances the plasma transport to the surrounding wall, increases the particle loss, and decreases the plasma density.

Shimada, Masashi

161

Nucleation and growth of Nb nanoclusters during plasma gas condensation  

NASA Astrophysics Data System (ADS)

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.

Bray, K. R.; Jiao, C. Q.; DeCerbo, J. N.

2013-06-01

162

Establishing isokinetic flow for a plasma torch exhaust gas diagnostic for a plasma hearth furnace  

SciTech Connect

Real time monitoring of toxic metallic effluents in confined gas streams can be accomplished through use of Microwave Induced Plasmas to perform atomic emission spectroscopy, For this diagnostic to be viable it is necessary that it sample from the flowstream of interest in an isokinetic manner. A method of isokinetic sampling was established for this device for use in the exhaust system of a plasma hearth vitrification furnace. The flow and entrained particulate environment were simulated in the laboratory setting using a variable flow duct of the same dimensions (8-inch diameter, schedule 40) as that in the field and was loaded with similar particulate (less than 10 {mu}m in diameter) of lake bed soil typically used in the vitrification process. The flow from the furnace was assumed to be straight flow. To reproduce this effect a flow straightener was installed in the device. An isokinetic sampling train was designed to include the plasma torch, with microwave power input operating at 2.45 GHz, to match local freestream velocities between 800 and 2400 ft/sec. The isokinetic sampling system worked as planned and the plasma torch had no difficulty operating at the required flowrates. Simulation of the particulate suspension was also successful. Steady particle feeds were maintained over long periods of time and the plasma diagnostic responded as expected.

Pollack, B.R.

1996-05-01

163

Female Sterilization: Risk of Ectopic Pregnancy After Tubal Sterilization  

MedlinePLUS

... Back to Female Sterilization Female Sterilization: Risk of Ectopic Pregnancy After Tubal Sterilization Fact Sheet Among 10,685 women studied, the risk of ectopic pregnancy within 10 years after sterilization was about 7 ...

164

Sterilizing the Poor  

ERIC Educational Resources Information Center

Suggests that freedom for the middle classes may mean vulnerability for the poor. The enthusiasm for sterilization may be so intense as to deprive the poor of their right not to be sterilized. (Author/AM)

Rothman, Sheila M.

1977-01-01

165

EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Boundary instability of an erosion laser plasma expanding into a background gas  

NASA Astrophysics Data System (ADS)

The stability of the contact region in the system consisting of an erosion plasma and a gas has been determined experimentally under conditions such that the length of the applied laser pulse is longer than the rise time of the instability, and the expansion of the erosion plume is accompanied by breakdown of the background gas. The evolution of perturbations of the plasma front following the introduction of initial perturbations with a fixed spatial period has been studied. It is possible to model the injection of plasma bunches into a low-pressure gas by studying the dynamics of the vaporization at moderate laser-light intensities, characteristic of technological applications.

Anisimov, V. N.; Grishina, V. G.; Derkach, O. N.; Kanevski?, M. F.; Sebrant, A. Yu

1993-12-01

166

The control of gas temperature and velocity fields of a RF induction thermal plasma by injecting secondary gas  

NASA Astrophysics Data System (ADS)

The present study describes the control characteristics of the gas temperature and velocity fields of a RF induction argon thermal plasma by injecting cold helium gas axially at atmospheric pressure. The flow and the gas temperature fields in the RF induction mixed gas plasma are obtained by solving the axisymmetric turbulent 2D MHD equations and the energy transport equation coupled with 2D Maxwell's equations. The mixing rate of a secondary injected gas is also calculated using the species conservation equation. It is examined how the thermofluid and diffusion characteristics of a RF induction plasma are influenced by the input power and the positions of injection of secondary gas and swirling. The calculated gas temperature shows good agreement with the previously obtained experimental data.

Nishiyama, Hideya; Muro, Yoshihiro; Kamiyama, Shinichi

1996-10-01

167

In situ measurement of gas composition changes in radio frequency plasmas using a quartz sensor  

NASA Astrophysics Data System (ADS)

A simple method using a quartz sensor (Q-sensor) was developed to observe gas composition changes in radio frequency (rf) plasmas. The output depends on the gases' absolute pressure, molecular weight, and viscosity. The pressure-normalized quartz sensor output depends only on the molecular weight and viscosity of the gas. Consequently, gas composition changes can be detected in the plasmas if a sensor can be used in the plasmas. Influences imparted by the plasmas on the sensor, such as those by reactive particles (e.g., radicals and ions), excited species, electrons, temperature, and electric potentials during measurements were investigated to test the applicability of this quartz sensor measurement to plasma. The Q-sensor measurement results for rf plasmas with argon, hydrogen, and their mixtures are reproducible, demonstrating that the Q-sensor measurement is applicable for plasmas. In this work, pressure- and temperature-normalized Q-sensor output (NQO) were used to obtain the gas composition information of plasma. Temperature-normalization of the Q-sensor output enabled quartz sensor measurements near plasma electrodes, where the quartz sensor temperature increases. The changes in NQO agreed with results obtained by gas analysis using a quadrupole mass spectrometer. Results confirmed that the change in NQO is mainly attributable to changes in the densities and kinds of gas molecules in the plasma gas phase, not by other extrinsic influences of plasma. For argon, hydrogen, and argon-hydrogen plasmas, these changes correspond to reduction in nitrogen, production of carbon monoxide, and dissociation of hydrogen molecules, respectively. These changes in NQO qualitatively and somewhat quantitatively agreed with results obtained using gas analysis, indicting that the measurement has a potential application to obtain the gas composition in plasmas without disturbing industrial plasma processes.

Suzuki, Atsushi; Nonaka, Hidehiko

2009-09-01

168

In situ measurement of gas composition changes in radio frequency plasmas using a quartz sensor.  

PubMed

A simple method using a quartz sensor (Q-sensor) was developed to observe gas composition changes in radio frequency (rf) plasmas. The output depends on the gases' absolute pressure, molecular weight, and viscosity. The pressure-normalized quartz sensor output depends only on the molecular weight and viscosity of the gas. Consequently, gas composition changes can be detected in the plasmas if a sensor can be used in the plasmas. Influences imparted by the plasmas on the sensor, such as those by reactive particles (e.g., radicals and ions), excited species, electrons, temperature, and electric potentials during measurements were investigated to test the applicability of this quartz sensor measurement to plasma. The Q-sensor measurement results for rf plasmas with argon, hydrogen, and their mixtures are reproducible, demonstrating that the Q-sensor measurement is applicable for plasmas. In this work, pressure- and temperature-normalized Q-sensor output (NQO) were used to obtain the gas composition information of plasma. Temperature-normalization of the Q-sensor output enabled quartz sensor measurements near plasma electrodes, where the quartz sensor temperature increases. The changes in NQO agreed with results obtained by gas analysis using a quadrupole mass spectrometer. Results confirmed that the change in NQO is mainly attributable to changes in the densities and kinds of gas molecules in the plasma gas phase, not by other extrinsic influences of plasma. For argon, hydrogen, and argon-hydrogen plasmas, these changes correspond to reduction in nitrogen, production of carbon monoxide, and dissociation of hydrogen molecules, respectively. These changes in NQO qualitatively and somewhat quantitatively agreed with results obtained using gas analysis, indicting that the measurement has a potential application to obtain the gas composition in plasmas without disturbing industrial plasma processes. PMID:19791966

Suzuki, Atsushi; Nonaka, Hidehiko

2009-09-01

169

ISO radiation sterilization standards  

NASA Astrophysics Data System (ADS)

This presentation provides an overview of the current status of the ISO radiation sterilization standards. The ISO standards are voluntary standards which detail both the validation and routine control of the sterilization process. ISO 11137 was approved in 1994 and published in 1995. When reviewing the standard you will note that less than 20% of the standard is devoted to requirements and the remainder is guidance on how to comply with the requirements. Future standards developments in radiation sterilization are being focused on providing additional guidance. The guidance that is currently provided in informative annexes of ISO 11137 includes: device/packaging materials, dose setting methods, and dosimeters and dose measurement, currently, there are four Technical Reports being developed to provide additional guidance: 1. AAMI Draft TIR, ``Radiation Sterilization Material Qualification'' 2. ISO TR 13409-1996, ``Sterilization of health care products - Radiation sterilization - Substantiation of 25 kGy as a sterilization dose for small or infrequent production batches'' 3. ISO Draft TR, ``Sterilization of health care products - Radiation sterilization Selection of a sterilization dose for a single production batch'' 4. ISO Draft TR, ``Sterilization of health care products - Radiation sterilization-Product Families, Plans for Sampling and Frequency of Dose Audits.''

Lambert, Byron J.; Hansen, Joyce M.

1998-06-01

170

Optimized method of producing washers of titanium hydride for plasma gun using occluded hydrogen gas  

Microsoft Academic Search

An optimized way of producing washers of titanium hydride for the application to a plasma gun using the occluded gas is presented. The amount of H2 gas (equivalently, gas pressure p) is entirely preadjusted in a gas reservoir of a simple instrument. The temperature T of a furnace is completely feedback controlled. Data show that when p is the order

H. Himura; Y. Saito; A. Sanpei; S. Masamune; N. Takeuchi; T. Shiono

2006-01-01

171

Initial experiments of RF gas plasma source for heavy ionfusion  

SciTech Connect

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.

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

2002-05-22

172

Measurement of Radial and Axial Neutral Gas Temperature in a Semi-Conductor Plasma Reactor  

SciTech Connect

Plasma-etching and plasma deposition processes are used in the fabrication of ultra large scale integration (ULSI) semi-conductor circuits. Plasma based processing systems have evolved from capacitive coupled plasma sources to high density inductively coupled and magnetically enhanced plasma sources. As processing evolves from 200-mm to 300-mm wafers and as critical dimensions continue to shrink continued improvement in a number of process variables, including process uniformity, are required. Process uniformity is governed by a number of factors including plasma density uniformity, reactive neutral uniformity, wafer temperature, and incident ion energy uniformity. The mechanisms leading to neutral radical non-uniformity, including gas heating and plasma pumping have been given less attention, therefore plasma diagnostics and modeling of neutral gas density, temperature, and dissociation in the reactor are needed to improve the understanding of how neutral gas conditions influence process uniformity. Radial and axial rotational temperature profiles in a large-area high-density plasma reactor (inductively coupled plasma discharge) have been obtained using the electron beam fluorescence technique (EBF) and optical emission spectroscopy (OES). These two diagnostics can provide the temperature measurements over the entire range of gas pressure (1-50mTorr) and input power (0-3000W). These two diagnostic techniques for temperature measurement are compared with a simple analytic model of gas heating and gas depletion.

Shimada, M.; Cattolica, R.; Tynan, G.R. [Department of Mechanical and Aerospace Engineering, MC 0417, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States)

2005-05-16

173

Flash X-ray microscopy with a gas jet plasma source.  

PubMed

A novel flash X-ray source, the gas jet plasma source, has been used for contact X-ray microscopy. Using a wavelength range of 2-7 nm a resolution of the order of 30 nm can be obtained. The gas jet plasma source provides a new and unique tool which should allow future imaging of wet live cells. PMID:6492145

Feder, R; Pearlman, J S; Riordan, J C; Costa, J L

1984-09-01

174

Interplay of discharge and gas flow in atmospheric pressure plasma jets  

Microsoft Academic Search

Interplay of discharge and gas flow in the atmospheric pressure plasma jets generated with three different discharge modes [N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 106, 013308 (2009); N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 108, 033302 (2010)] has been investigated by simultaneous photographing of both plasma plumes and gas

Nan Jiang; Jinglong Yang; Feng He; Zexian Cao

2011-01-01

175

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

Microsoft Academic Search

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

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

2010-01-01

176

Comparing the equivalent particle number density distribution of gas and plasma flow fields.  

PubMed

In this paper, the equivalent particle number density distribution of gas and plasma flow fields is investigated. For the purpose of facilitating comparison, argon gas and argon arc plasma are chosen as practical examples for experiment. The equivalent particle number density distributions of the argon gas and argon arc plasma are reconstructed from the experimentally measured refractive index distributions obtained by moiré tomography, while five cross sections, which are 7, 8.5, 10, 11.5, and 13 mm away from the jet nozzle are chosen for practical calculation and comparison. In experiment, the probe wavelength and the export pressure of argon gas and argon arc plasma are the same. The experimental results manifest that (1) the equivalent particle number density decreases with the distance away from the jet nozzle of the gas flow field, while (2) the equivalent particle number density of the plasma flow field has a different variation. Finally, the experimental results are theoretically explained and analyzed. PMID:23669673

Chen, Yun-yun; Zhang, Ying-ying; Zhang, Cheng-yi; Li, Zhen-hua

2013-04-20

177

Effects of ionic liquid electrode on pulse discharge plasmas in the wide range of gas pressures  

SciTech Connect

Gas-liquid interfacial pulse discharge plasmas are generated in the wide range of gas pressures, where an ionic liquid is used as the liquid electrode. By analyzing the characteristics of discharge voltage and current, the discharge mechanisms at low and high pressures are found to be dominated by secondary electron emission and first Townsend ionization, respectively. Therefore, the discharge properties at low and high pressures are mainly determined by the cathode material and the discharge gas type, respectively. Furthermore, the plasma properties are investigated by a double Langmuir probe. The density of the positive pulse plasma is found to be much smaller than that of the negative pulse plasma, although the discharge voltage and current of the negative and positive pulse plasmas are of the same order of magnitude. The positive pulse discharge plasma is considered to quickly diffuse onto the chamber wall from the radially central region due to its high plasma potential compared with that in the peripheral region.

Chen Qiang; Hatakeyama, Rikizo [Department of Electronic Engineering, Tohoku University, Aoba-yama 05, Sendai 980-8579 (Japan); Kaneko, Toshiro [Department of Electronic Engineering, Tohoku University, Aoba-yama 05, Sendai 980-8579 (Japan); CREST/JST, 5, Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan)

2010-11-15

178

Gas transport characteristics of plasma treated poly(dimethylsiloxane) and polyphosphazene membrane materials  

Microsoft Academic Search

Gas permeability coefficients for poly(dimethylsiloxane) (PDMS) and a series of polyphosphazene (PPh) materials are measured before and after 30W argon radio frequency (RF)-plasma surface treatments. The gas transport properties of the entire series of PPh materials are relatively unaffected by the plasma treatments. In contrast with the PPhs, the same plasma treatment conditions lead to 40–80% reductions in PDMS oxygen

K. S Houston; D. H Weinkauf; F. F Stewart

2002-01-01

179

Direct Injection Multi-Gas Inductively Coupled Plasma Source for Industrial Applications  

Microsoft Academic Search

Summary form only given. A new direct injection multi-gas inductively coupled plasma (ICP) source is developed. With the new ICP source, not only Ar but He, O2, N2, CO2, air and their mixture gas plasma can be stably generated in the atmospheric pressure. Furthermore, aqueous solutions can be introduced directly into the plasmas using common pneumatic nebulizer. To generate molecular

Akitoshi Okino; Hidekazu Miyahara; Takayuki Doi; Yoichi Mizusawa; Eiki Hotta

2005-01-01

180

Measurements of Plasma Expansion due to Background Gas in the Electron Diffusion Gauge Experiment  

SciTech Connect

The expansion of pure electron plasmas due to collisions with background neutral gas atoms in the Electron Diffusion Gauge (EDG) experiment device is observed. Measurements of plasma expansion with the new, phosphor-screen density diagnostic suggest that the expansion rates measured previously were observed during the plasma's relaxation to quasi-thermal-equilibrium, making it even more remarkable that they scale classically with pressure. Measurements of the on-axis, parallel plasma temperature evolution support the conclusion.

Kyle A. Morrison; Stephen F. Paul; Ronald C. Davidson

2003-08-11

181

Emission characteristics of mixed gas plasmas in low-pressure glow discharges  

Microsoft Academic Search

Glow discharge optical emission spectrometry (GD-OES) with mixed plasma gases is reviewed. The major topic is the effect of type and content of gases added to an argon plasma on the emission characteristics as well as the excitation processes. Emphasis is placed on argon–helium, argon–oxygen, and argon–nitrogen mixed gas plasmas. Results for non-argon-matrix plasmas, such as neon–helium and nitrogen–helium mixtures,

Kazuaki Wagatsuma

2001-01-01

182

Female Tubal Sterilization  

PubMed Central

Tubal ligation has become the second most popular method of contraception in Canada, after oral contraception. Refinement of techniques has resulted in sterilization procedures which have minimal potential for failure and high potential for reversibility. Laparoscopic and minilaparatomy techniques allow outpatient “Band-Aid” sterilizations with less risk of complications than more destructive procedures. Laparoscopic application of tubal clips or rings is highly effective, with minimal tubal destruction. Tubal ligation following a pregnancy is more often regretted than is interval sterilization. The search continues for a satisfactory transcervical sterilization procedure.

Rowe, Timothy C.; Pabuccu, Recai

1986-01-01

183

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

NASA Astrophysics Data System (ADS)

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.

McClure, John C.; Hou, Haihui Ron

1994-08-01

184

A sensitive assay of 5-fluorouracil in plasma by gas chromatography-mass spectrometry.  

PubMed Central

1 A gas chromatographic-mass spectrometric method was developed for determining 5-fluorouracil in plasma, using methylated thymine as an internal standard. 2 5-fluorouracil was extracted from plasma by a novel procedure which removed plasma components interferring with the sensitivity of the assay. The method included heating the plasma, washing with ether and extracting the drug under optimum conditions. 3 The sensitivity of the assay was 10 ng/ml plasma, sufficient to determine the low concentrations of 5-fluorouracil found in plasma during continuous infusion of the drug in patients receiving chemotherapy for cancer.

Hillcoat, B L; Kawai, M; McCulloch, P B; Rosenfeld, J; Williams, C K

1976-01-01

185

Genetic male sterility in wheat  

Microsoft Academic Search

The occurrence of genetic male sterility and development of highly sterile lines have been reported. The male sterility was not accompanied by any visible chromosomal aberration. It behaved as recessive and was governed by multiple factors. It was hypothesised that three major genes with additive effect were operating to produce highly sterile forms while less sterile forms would be dependent

D. S. Athwal; P. S. Phul; J. L. Minocha

1967-01-01

186

Further development of plasma electron gun for operation at forepump gas pressure  

Microsoft Academic Search

The hollow cathode plasma electron gun was designed especially for operation at forepump (up to 0.1 Torr) gas pressure. This work is devoted to investigation of maximum values of gas pressure and accelerating voltage It was established, that the maximum. operation gas pressure as well as the electron accelerating voltage increased with the smaller emission mesh size, shorter accelerating gap

Y. Burachevsky; V. Burdovitsin; D. Danilishin; A. Mytnikov; E. Oks

2001-01-01

187

Transport in a field-aligned magnetized plasma and neutral gas boundary: the end of the plasma  

NASA Astrophysics Data System (ADS)

A series of experiments at the Enormous Toroidal Plasma Device (ETPD) at UCLA study the Neutral Boundary Layer (NBL) between a magnetized plasma and a neutral gas in the direction of the confining field. A lanthanum hexaboride (LaB6) cathode and semi-transparent anode create a current-free, weakly ionized (ne/nn<5%), helium plasma (B˜250 G, Rplasma=10cm, ne<10^12cm^3, Te<3eV, and Ti˜Tn) that terminates on helium gas without touching any walls. Probes inserted into the plasma measure the basic plasma parameters in the NBL. The NBL begins where the plasma and neutral gas pressures equilibrate and the electrons and ions come to rest through collisions with the neutral gas. A field-aligned electric field (??/kTe˜1) is established self-consistently to maintain a current-free termination and dominates transport in the NBL, similar to a sheath but with a length L˜10?ei˜10^2?en˜10^5?D. A two-fluid weakly-ionized transport model describes the system. A generalized Ohm's Law correctly predicts the electric field observed. The pressure balance criteria and magnitude of the termination electric field are confirmed over a scaling of parameters. The model can also be used to describe the atmospheric termination of aurora or fully detached gaseous divertors.

Cooper, Christopher; Gekelman, Walter

2012-10-01

188

The pros and cons of polyethylene sterilization with gamma irradiation.  

PubMed

This retrospective study evaluated the implant, patient and surgical factors associated with polyethylene wear for one type of porous-coated hemispheric total hip arthroplasty cup. Radiographic wear measurements among 567 Duraloc cups (512 patients) revealed that liners sterilized by gamma-irradiation wore 0.085 mm/year less than those that were sterilized by gas-plasma, a noncross-linking chemical surface treatment. The substantially decreased wear rate associated with gamma-irradiation was attributed to sterilization-induced polyethylene cross-linking. Shelf-aging adversely affected liners that were gamma irradiated in air. On average, highly crystalline Hylamer liners showed a 0.064 mm/year increase in wear rates for each year of shelf storage after terminal sterilization with gamma-irradiation in air. Among conventional Enduron liners, the effect of shelf aging after gamma-irradiation in air was more modest, increasing wear rates by 0.014 mm/year for each year of shelf storage. Because Hylamer's wear performance degraded at about five times the rate of Enduron's, the improved wear resistance associated with gamma-irradiation in air would be lost after 1.3 years of shelf aging for Hylamer compared with 6.1 years for Enduron. For every additional year of age at the time of surgery, the wear rate decreased by 0.003 mm/year. Increased body mass index, a preoperative diagnosis of inflammatory arthritis, and a ceramic femoral head also were associated with decreased wear rates. PMID:15577466

Hopper, Robert H; Engh, C Anderson; Fowlkes, LaTonya B; Engh, Charles A

2004-12-01

189

Investigations of lower hybrid wave-plasma coupling by gas puffing in HT-7  

SciTech Connect

Lower hybrid wave (LHW)-plasma coupling experiments in HT-7 [J. K. Xie and HT-7 Group, Proceedings of the 16th International Conference on Fusion Energy, Montreal, 1996 (IAEA, Trieste, 1997), Vol. 1, p. 685] were carried out by means of puffing gas (CD{sub 4} and D{sub 2}) just around the antenna. Both experiments show that wave-plasma coupling is improved by the gas puffing. The maximum distance between the plasma and the antenna is limited to about 8 cm due to the plasma disruption. The variation in the lined averaged density in the different channels gives a possible evidence of the mechanism of the ionization of neutral gas. The effect of the gas flow rate on the wave-plasma coupling shows that an optimized gas flow rate is necessary for good coupling, being consistent with simulation through Brambilla theory qualitatively. Experiments with puffing D{sub 2} show that the improved coupling results from the global density increase and the local gas puffing. Langmuir probe measurements indicate that the gas puffing effectively increases the density and decreases the temperature in scrape of layer. Studies show that the ionization of the puffed gas is affected by both LHW electric field and plasma temperature. Comparison of D{sub 2} and CD{sub 4} puffing shows that D{sub 2} improves coupling better with less effect on core density.

Ding, B. J.; Li, M. H.; Qin, Y. L.; Li, W. K.; Zhang, L. Z.; Shan, J. F.; Liu, F. K.; Wang, M.; Meng, L. G.; Xu, H. D.; Wang, D. X.; Jie, Y. X.; Sun, Y. W.; Shen, B.; Zhang, W.; Wang, X. M.; Wu, J. H.; Gao, X.; Zhang, X. D.; Zhao, Y. P. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2010-02-15

190

Transient effects caused by pulsed gas and liquid injections into low pressure plasmas  

NASA Astrophysics Data System (ADS)

The fast injection of liquid droplets into a glow discharge causes significant time variations in the pressure, the chemical composition of the gas and the phases present (liquid and/or solid along with gas). While the variations can be large and important, very few studies, especially kinetic studies, have been published. In this paper we examine the changes brought about in argon plasma by injecting Ar (gas), N2 (gas) hexane (gas) and hexane (liquid droplets). The changes in the RF capacitively coupled power (forward and reflected), electron and ion density (ne, ni), electron temperature (Te) and optical emissions were monitored during the injections. It was found that the Ar injection (pressure change only) caused expected variations. The electron temperature reduced, the plasma density increased and the optical emission intensity remained nearly constant. The N2 and hexane gas injections (chemical composition and pressure changes) also followed expected trends. The plasma densities increased and electron temperature decreased while the optical emissions changed from argon to the injected gas. These all serve to highlight the fact that the injection of evaporating hexane droplets in the plasma caused very little change. This is because the number of injected droplets is too small to noticeably affect the plasma, even though the shift in the chemical composition of the gas caused by evaporation from those same droplets can be very significant. The net conclusion is that using liquid droplets to inject precursors for low pressure plasmas is both feasible and controllable.

Ogawa, D.; Chung, C. W.; Goeckner, M.; Overzet, L.

2010-06-01

191

Investigations of lower hybrid wave-plasma coupling by gas puffing in HT-7  

NASA Astrophysics Data System (ADS)

Lower hybrid wave (LHW)-plasma coupling experiments in HT-7 [J. K. Xie and HT-7 Group, Proceedings of the 16th International Conference on Fusion Energy, Montreal, 1996 (IAEA, Trieste, 1997), Vol. 1, p. 685] were carried out by means of puffing gas (CD4 and D2) just around the antenna. Both experiments show that wave-plasma coupling is improved by the gas puffing. The maximum distance between the plasma and the antenna is limited to about 8 cm due to the plasma disruption. The variation in the lined averaged density in the different channels gives a possible evidence of the mechanism of the ionization of neutral gas. The effect of the gas flow rate on the wave-plasma coupling shows that an optimized gas flow rate is necessary for good coupling, being consistent with simulation through Brambilla theory qualitatively. Experiments with puffing D2 show that the improved coupling results from the global density increase and the local gas puffing. Langmuir probe measurements indicate that the gas puffing effectively increases the density and decreases the temperature in scrape of layer. Studies show that the ionization of the puffed gas is affected by both LHW electric field and plasma temperature. Comparison of D2 and CD4 puffing shows that D2 improves coupling better with less effect on core density.

Ding, B. J.; Li, M. H.; Qin, Y. L.; Li, W. K.; Zhang, L. Z.; Shan, J. F.; Liu, F. K.; Wang, M.; Meng, L. G.; Xu, H. D.; Wang, D. X.; Jie, Y. X.; Sun, Y. W.; Shen, B.; Zhang, W.; Wang, X. M.; Wu, J. H.; Gao, X.; Zhang, X. D.; Zhao, Y. P.; HT-7 Team

2010-02-01

192

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

NASA Astrophysics Data System (ADS)

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.

Jin, Dong Jun; Uhm, Han S.; Cho, Guangsup

2013-08-01

193

Atomic Force Microscope Investigations of Bacterial Biofilms Treated with Gas Discharge Plasmas  

NASA Astrophysics Data System (ADS)

We present investigations of bacterial biofilms before and after treatment with gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve biofilm communities, where bacteria grow embedded in an exopolysaccharide matrix, and cooperative interactions between cells make organisms less susceptible to standard inactivation methods. In this study, biofilms formed by the opportunistic bacterium Pseudomonas aeruginosa were imaged before and after plasma treatment using an atomic force microscope (AFM). Through AFM images and micromechanical measurements we observed bacterial morphological damage and reduced AFM tip-sample surface adhesion following plasma treatment.

Vandervoort, Kurt; Zelaya, Anna; Brelles-Marino, Graciela

2012-02-01

194

The Plasma Column Evolution in Gas-Puff Z-Pinches on the Yang Accelerator  

SciTech Connect

The plasma column evolution in gas-puff z-pinch was investigated on the Yang accelerator. The pinch process was significantly influenced by the initial gas distribution. Uniformity of the gas-puff distribution resulted in the asymmetry of the initially load current through the main channels of the plasma layer. The zipper velocity and implosion speed under 'trumpet' distribution was given, it was observed the pinch speed and the temperature of the plasma near cathode increased when the rise time of the load current was shortened.

Deng Jianjun; Yang Libing; Gu Yuanchao; Huang Xianbing; Li Fengping; Xv Zeping; Ye Shican; Cheng Guanghua; Chang Lihua; Zhou Shaotong; Zhang Siqun; Xie Weiping; Ding Bonan; Peng Xianjue [China Academy of Engineer Physics, P.O.Box 919-150, Mianyang, Sichuan, 621900 (China)

2006-01-05

195

The Plasma Column Evolution in Gas-Puff Z-Pinches on the Yang Accelerator  

NASA Astrophysics Data System (ADS)

The plasma column evolution in gas-puff z-pinch was investigated on the Yang accelerator. The pinch process was significantly influenced by the initial gas distribution. Uniformity of the gas-puff distribution resulted in the asymmetry of the initially load current through the main channels of the plasma layer. The zipper velocity and implosion speed under ``trumpet'' distribution was given, it was observed the pinch speed and the temperature of the plasma near cathode increased when the rise time of the load current was shortened.

Deng, Jianjun; Yang, Libing; Gu, Yuanchao; Huang, Xianbing; Li, Fengping; Xv, Zeping; Ye, Shican; Cheng, Guanghua; Chang, Lihua; Zhou, Shaotong; Zhang, Siqun; Xie, Weiping; Ding, Bonan; Peng, Xianjue

2006-01-01

196

Kinetic temperature and charge of a dust grain in weakly ionized gas-discharge plasmas  

SciTech Connect

Analytical relations are given for estimating the energy of the stochastic motion of an individual dust grain heated by electrostatic ion oscillations in a weakly ionized gas-discharge plasma. Dust grain charging processes are analyzed, and an empirical approximation is obtained for the ion current to the grain surface. The processes are simulated under conditions similar to those of laboratory experiments on dusty plasmas. It is found that the kinetic temperature of a dust grain heated by electrostatic ion oscillations in a gas-discharge plasma can exceed the background gas temperature.

Vaulina, O. S., E-mail: vaul@ihed.ras.ru; Repin, A. Yu.; Petrov, O. F.; Adamovich, K. G. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation)

2006-06-15

197

Unintended Pregnancy Prevention: Female Sterilization  

MedlinePLUS

... Medicine. Questions and Answers About the U.S. Collaborative Review of Sterilization Study of Tubal Sterilization and Menstruation Background: An article presenting results of the Collaborative Review of Sterilization (CREST) study was published in the ...

198

Study of plasma—solid interaction in electronegative gas mixtures  

Microsoft Academic Search

Low-temperature reactive plasmas employing electronegative gases are often used in modern technologies. Negative ions in such\\u000a plasmas affect the transport of charged species and in this way influence the processes in the boundary layer between plasma\\u000a and surface of metal substrate or probe. The contribution presents results of the computer experiment describing the interaction\\u000a of electronegative plasma with immersed substrates.

Rudolf Hrach; Ji?í Šimek; Vera Hrachová

2006-01-01

199

Two-dimensional cylindrical plasma for intermediate gas pressures  

NASA Astrophysics Data System (ADS)

A two-dimensional hydrodynamic model for a bounded plasma cylinder is developed. This model establishes a bridge between the two limiting cases presented by Godyak and Sternberg (2008 Plasma Sources Sci. Technol. 17 0250042): the diffusion-controlled regime and the free-fall regime. An analysis of the bounded plasma cylinder with arbitrary aspect ratios and arbitrary collisionality is presented. Plasma parameters relevant in applications are found for a wide range of aspect ratios and collisionality.

Sternberg, Natalia; Godyak, Valery

2011-02-01

200

Nanosecond laser pulse interactions with breakdown plasma in gas medium confined in a microhole  

NASA Astrophysics Data System (ADS)

The previous investigations on nanosecond laser pulse interactions with breakdown plasma in a gas medium confined in a microhole have been limited. This kind of plasma has been studied in this paper. Due to the significant measurement difficulty resulted from the very small spatial and temporal scales involved, a physics-based computational model has been employed as the investigation tool. The model is developed by solving gas dynamic equations numerically using the finite difference method based on an essentially non-oscillatory scheme. The gas dynamic equations are coupled with suitable equation of state, where the electron number density for plasma region is calculated through the Saha equation. Using the model, the spatial confinement effects of the microhole sidewall on the plasma evolution under laser radiation have been investigated. It has been found that under the studied conditions the hole sidewall confinement can greatly enhance the plasma temperature, pressure, and thrust (over the same surface area). The enhancement should be due to the sidewall's restriction on the plasma lateral expansion and the sidewall's reflection of the pressure wave induced by plasma. This study implies potential advantages of the breakdown plasma confined in a microhole in many relevant applications, such as laser propulsion and laser-induced breakdown spectroscopy. The developed model also provides a useful guiding tool for future fundamental research and practical applications in many areas related to laser interactions with gas breakdown plasma.

Tao, Sha; Wu, Benxin

2013-05-01

201

Experimental and numerical studies of neutral gas depletion due to neural gas collisional heating in an inductively coupled plasma  

NASA Astrophysics Data System (ADS)

The significant neutral gas temperature rise has been observed in various noble gases in the center of an inductively coupled plasma (ICP) chamber and the actual neutral gas pressure has been obtained by considering the thermal transpiration effects with this neutral gas increase. A plate which consists of 8 vertical optical ports with collimating lens and a movable optical fiber probe have been developed and used to measure axial and radial profile of gas temperature in an ICP respectively. When thermal transpiration is accounted for, our neutral pressure measurement shows the gas pressure remains the same as the fill pressure when plasma is on. Since the neutral gas presumably follows the ideal gas law, p=nT, our results therefore imply that the neutral gas density is significantly reduced in the central region of the discharge chamber. 0D/1D neutral gas heating model has been developed and compared with experimental results. DSMC (Direct Simulation Monte Carlo) has been carried out to simulate the ion acceleration in collisional pre-sheath and charge exchange/elastic collisions with background neutral gas.

Shimada, Masashi

2005-10-01

202

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

NASA Astrophysics Data System (ADS)

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 × 1018 cm-3, the peak normalized laser vector potential, a0, increases from 1.0 to 1.85 close to the entrance plane of the capillary compared with a0 = 1.41 when the plume is neglected.

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

2013-09-01

203

Static gas-liquid interfacial direct current discharge plasmas using ionic liquid cathode  

SciTech Connect

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we have succeeded in creating the static and stable gas (plasmas)-liquid (ionic liquids) interfacial field using a direct current discharge under a low gas pressure condition. It is clarified that the ionic liquid works as a nonmetal liquid electrode, and furthermore, a secondary electron emission coefficient of the ionic liquid is larger than that of conventional metal electrodes. The plasma potential structure of the gas-liquid interfacial region, and resultant interactions between the plasma and the ionic liquid are revealed by changing a polarity of the electrode in the ionic liquid. By utilizing the ionic liquid as a cathode electrode, the positive ions in the plasma region are found to be irradiated to the ionic liquid. This ion irradiation causes physical and chemical reactions at the gas-liquid interfacial region without the vaporization of the ionic liquid.

Kaneko, T. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan); CREST/JST, Tokyo 102-0075 (Japan); Baba, K.; Hatakeyama, R. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan)

2009-05-15

204

Effects of Gas Plasma Treatments on Surface Properties of Commercial Polymer Films.  

National Technical Information Service (NTIS)

Surface properties of various commercial polymer films have been studied before and after a brief exposure to low-temperature gas plasmas. The surface properties investigated include wettability by water and how well vapor-deposited aluminum adhered to th...

M. Binder R. J. Mammone W. L. Wade

1991-01-01

205

Enhancement of Gas Response of ZnO Micro-nano Structured Films through O2 Plasma Treatment  

Microsoft Academic Search

Layers of ZnO micro-nano structures were deposited on quartz substrates and subsequently plasma treated in O2 and N2. It was found that exposure to O2 plasma enhanced gas response to ethanol vapor of the ZnO layers by a factor eight, while exposure to N2 plasma deteriorated the gas response. The gas response enhancement upon O2 plasma treatment could be correlated

Ippei Nagatomo; Ryohei Uchino; Yanbo Li; Masaki Shuzo; Ichiro Yamada; Jean-Jacques Delaunay

2009-01-01

206

Neutral gas temperatures measured within a high-density, inductively coupled plasma abatement device  

Microsoft Academic Search

The neutral temperature within a cylindrical, inductively coupled plasma source has been studied for rare gas and molecular plasmas using the technique of optical emission thermometry. By adding small quantities of N2 to the gas feeds as an actinometer, the neutral temperature of the discharge can be estimated by simulation and fitting of the rotationally unresolved second positive band (C3Pi]u-B3[Pig).

Eric J. Tonnis; David B. Graves

2002-01-01

207

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

NASA Astrophysics Data System (ADS)

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.

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

2007-04-01

208

An experimental study of gas plasma flow in a rail gun at atmospheric pressure  

Microsoft Academic Search

Results of an experimental study of the pulsed flow structure in a rail gun with an external magnetic field in the quasi-stationary discharge current regime are reported. In the gas plasma flow induced by the moving discharge in the rail gun, the gas-discharge plasma region is shown to be a strong-turbulence zone. The shock wave velocity, discharge velocity, and the

A. N. Smolianinov; Iu. V. Tushko; A. S. Chiganov

1988-01-01

209

Influence of gas composition on plasma arc cutting of mild steel  

Microsoft Academic Search

We report the results of a study on the influence of oxygen in the plasma gas used in the plasma arc cutting process on cuts obtained in mild steel plates. Experimental results of shapes of kerfs and the leading edges of the cut front formed while cutting a 6 mm mild steel plate at 100 A with nitrogen, air and

S. Ramakrishnan; V. Shrinet; F. B. Polivka; T. N. Kearney; P. Koltun

2000-01-01

210

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

Microsoft Academic Search

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

Lei Zhang Schlitz

1998-01-01

211

Non-thermal plasmas as gas-phase advanced oxidation processes  

SciTech Connect

Non-thermal plasmas are useful for generating reactive species (free radicals) in a gas stream. Because radical attack reaction rate constants are very large for many chemical species, entrained pollutants are readily decomposed by radicals. Such plasmas can generate both oxidative and reductive radicals; therefore, they show promise for treating a wide variety of pollutants.

Rosocha, L.A.

1997-08-01

212

Transport of microparticles in weakly ionized gas-discharge plasmas under microgravity conditions.  

PubMed

Measurements of effective structural (pair correlation function) and transport (diffusion constant) characteristics of the system of microparticles in dc and rf gas-discharge plasmas under microgravity conditions are reported. The comparison between these measurements and numerical simulations is used for complex plasma diagnostics. PMID:12857198

Fortov, V E; Vaulina, O S; Petrov, O F; Molotkov, V I; Lipaev, A M; Torchinsky, V M; Thomas, H M; Morfill, G E; Khrapak, S A; Semenov, Yu P; Ivanov, A I; Krikalev, S K; Kalery, A Yu; Zaletin, S V; Gidzenko, Yu P

2003-06-19

213

Measurements of Temperature and Chemical Composition in a Thermal Plasma Reactor for Waste Gas Pyrolysis  

Microsoft Academic Search

Summary form only given. For the cleaning treatment of hazardous waste gases by pyrolysis, thermal plasmas have been introduced taking advantage of their extremely high temperature and enthalpy. However, the high-temperature decomposition region of a thermal plasma jet, having steep temperature gradients both in the radial and axial directions, is so narrow that the waste gas injected into it has

Hyun Seok Lee; Sooseok Choi; Chan Min Lee; Sang Hee Hong

2007-01-01

214

Efficient Synthesis of Gold Nanoparticles Using Ion Irradiation in Gas--Liquid Interfacial Plasmas  

NASA Astrophysics Data System (ADS)

The efficient synthesis of gold nanoparticles using plasma irradiation in gas--liquid interfacial discharges is carried out. The availability of plasma ion irradiation to an ionic liquid on nanoparticle synthesis was revealed by direct comparison with an electron shower system. It was found that the ion irradiation generated hydrogen radicals in the ionic liquid, which were effective for the synthesis of gold nanoparticles.

Baba, Kazuhiko; Kaneko, Toshiro; Hatakeyama, Rikizo

2009-03-01

215

Removal of NOx and SO2 in flue gas by corona plasma reactor with water film  

Microsoft Academic Search

NOx and SO2 removal methods using plasma chemical reactions in nonthermal plasma have been widely studied. In this paper, a novel type of corona discharge model with water film was designed. The reactor is composed of needle-plate electrodes that are placed in a glass container filled with the flue gas, (the plate electrode is immersed in the water). The influence

Limin Dong; Jiaxiang Yang

2002-01-01

216

Study of atmospheric plasma spray process with the emphasis on gas-shrouded nozzles  

Microsoft Academic Search

An atmospheric plasma spraying process is investigated in this work by using experimental approach and mathematical modelling. Emphasis was put on the gas shrouded nozzles, their design, and the protection against the mixing with the surrounding air, which they give to the plasma jet. First part of the thesis is dedicated to the analysis of enthalpy probe method, as a

Miodrag M. Jankovic

1997-01-01

217

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

Microsoft Academic Search

The discharge plasma-chemical hybrid process for NOx removal from the due 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

T. Yamamoto; B. S. Rajanikanth; M. Okubo; T. Kuroki; M. Nishino

2001-01-01

218

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

NASA Astrophysics Data System (ADS)

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.

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

1983-02-01

219

Direct Measurement of the Gas Entrainment Into a Turbulent Thermal Plasma Jet  

Microsoft Academic Search

An experimental study is conducted to investigate the entrainment characteristics of a turbulent thermal plasma jet issuing\\u000a from a DC arc plasma torch operating at atmospheric pressure. The mass flow rate of the ambient gas entrained into the turbulent\\u000a plasma jet is directly measured by use of the so-called “porous-wall chamber” technique. It is shown that a large amount of

Hai-Xing Wang; Fu-Zhi Wei; Xian Meng; Xi Chen; Dong-Sheng Han; Wen Xia Pan

2011-01-01

220

REVIEW ARTICLE: Carbon nanostructures production by gas-phase plasma processes at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Carbon nanostructures have received much attention for a wide range of applications. This paper reviews the historical role of plasmas in the gas-phase synthesis of carbon nanostructures and the present plasma technologies for industrial production purposes. It enumerates the advantages and disadvantages with respect to concurrent technologies commonly employed nowadays. Finally, some carbon nanostructures produced in our laboratory will serve as examples of the plasma processes potential.

Gonzalez-Aguilar, J.; Moreno, M.; Fulcheri, L.

2007-04-01

221

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

NASA Astrophysics Data System (ADS)

To understand plasma-induced chemical processing in liquids, we investigated the formation of free radicals in aqueous solution exposed to different types of non-contact atmospheric-pressure helium plasma using the spin-trapping technique. Both hydroxyl radical (OH.) and superoxide anion radical (O2-.) adducts were observed when neutral oxygen gas was additionally supplied to the plasma. In particular, O2-. can be dominantly induced in the solution via oxygen flow into the afterglow gas of helium plasma. This type of plasma treatment can potentially be used in medical applications to control infectious diseases, because the O2-. is crucial for sterilization of liquids via atmospheric-pressure plasma.

Tani, Atsushi; Ono, Yusuke; Fukui, Satoshi; Ikawa, Satoshi; Kitano, Katsuhisa

2012-06-01

222

[Comparative study on the gas temperature of a plasma jet at atmospheric pressure].  

PubMed

A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce jet plasma in flowing work gas (argon mixed with trace nitrogen) at atmospheric pressure. The relation between the plasma length and the gas flow rate was obtained by taking the images of the jet plasma. A high-resolution optical spectrometer was used to collect the optical emission spectrum. The emission spectra of the first negative band of N(2+) (B2 Sigma(u+)-->Chi2 Sigma(g+), 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The gas temperature was investigated by this optical method and results show that the gas temperature increases with increasing the applied voltage. For comparison, a thermometer was used to measure the temperature of the gas emitted from the jet. The results also show that the gas temperature increases with increasing the applied voltage. The gas temperatures obtained by the two methods are consistent. The difference was analyzed. PMID:22007378

Jia, Peng-Ying; Li, Xue-Chen; Yuan, Ning

2011-08-01

223

Modeling of non-thermal plasma in flammable gas mixtures  

Microsoft Academic Search

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

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

2008-01-01

224

Influence of the gas mixture temperature on the efficiency of synthesis gas production from ethanol in a nonequilibrium plasma  

NASA Astrophysics Data System (ADS)

The mechanism behind the plasma conversion of a mixture of ethanol vapor, water vapor, air, and carbon dioxide CO2 in the nonequilibrium plasma of a tornado discharge is studied. The influence of the CO2 flow rate, the current through the discharge, and the gas temperature in the discharge on the concentrations of molecular hydrogen and carbon monoxide CO is studied. Comparison between the concentrations of the gaseous mixture's main components at the output from the reactor obtained experimentally and by numerical simulation shows that the adopted kinetic mechanism adequately describes the plasma kinetics in the mixture.

Tsymbalyuk, A. N.; Levko, D. S.; Chernyak, V. Ya.; Martysh, E. V.; Nedybalyuk, O. A.; Solomenko, E. V.

2013-08-01

225

Female Sterilization (Tubal Ligation)  

MedlinePLUS

... C. Hysteroscopic sterilization: This procedure is called the " Essure " method and is done in an operating or ... 3 months . A follow-up test called the Essure Confirmation Test is done within 3 months after ...

226

Sterile neutrino mixing with ??  

NASA Astrophysics Data System (ADS)

Matrix element U?N of sterile neutrino N mixing with ?? is the least constrained in the literature among the three U?N (?=e, ?, ?) mixing parameters characterizing the sterile neutrino phenomenology. We study the contribution of massive dominantly sterile neutrinos to purely leptonic ? decays and semileptonic decays of ? and K, D mesons. We consider some decays allowed in the standard model as well as lepton flavor and lepton number violating decays forbidden in the standard model. From the existing experimental data on the branching ratios of these processes we derived new limits on U?N more stringent than the ones existing in the literature. These limits are extracted in a model independent way without any ad hoc assumptions on the relative size of the three different sterile neutrino mixing parameters.

Helo, Juan Carlos; Kovalenko, Sergey; Schmidt, Ivan

2011-09-01

227

Counseling for sterilization.  

PubMed

The standards of the Department of Health and Human Services (DHHS) regarding the provision of sterilization services fail to deal with the need for professionally trained sterilization counselors to present the medical, social, and related information in a manner that prospective patients can understand and retain. Sterilization patients require counseling by a person who is competent, experienced, warm, and supportive of their decision. A good counselor will remain non-judgmental and objective. A counseling session with a prospective sterilization patient should have the following specific objectives: help the woman understand her feelings about birth control, pregnancy, abortion, and possible relationships between sexuality and reproductive capacity; help her understand her own reproductive anatomy and physiology; help her understand the sterilization procedure and what she can expect to experience; help her project her thoughts to the future to see if she can think of any life situation in which she might want to become pregnant; and fulfill the legal requirements for obtaining informed consent. The direction and consent of any interview will be influenced by several factors, such as marital status or lifestyle of the prospective candidate. The ideal situation for postpartum sterilization would include counseling and arrangements made long before the onset of labor. Specialized counseling is also valuable when delivery is to be by cesarean section, for in these instances a last minute change of plan is not possible. If female sterilization is to be performed under local anesthesia, the patient should be prepared for the possible discomfort or actual pain that might occur. The counselor also needs to be alert to indications of a special need for in-depth discussion. Such indications include the individual who has a physical, mental, or emotional condition that would be improved by sterilization. Any evidence of coercion should be regarded as a contraindication to sterilization. Those persons depending on possible reversal of sterilization require special attention, but old restrictions on voluntary sterilization based on age and parity should be discarded. A counselor is obligated to present the arguments against successful reversal in individual cases while making it clear that reversals are increasingly successful. Good counseling does much to eliminate regret or at least reduces it to an absolute minimum. PMID:7310766

Gonzales, B L

1981-10-01

228

Counseling Women Who Request Sterilization  

Microsoft Academic Search

With large numbers of women seeking sterilization each year, including over half a million in 1983 alone, the problem of regretted sterilization and efforts to prevent regret have become matters of concern to health care providers. This paper describes a sterilization counseling program designed to reduce the likelihood of regretted sterilization. Discussed are factors which help predict satisfaction or regret

Ingrid Kohn

1986-01-01

229

Hybrid sterility in the mouse  

Microsoft Academic Search

The sterility of bybrids between various mouse species follows Haldane's rule by affecting only the males. Hitberto, five bybrid sterility (Hst) loci have been identified in the mouse genome. Haldane's rule bolds also for chromosomal sterility in all studied mammalian species, including man. The males heterozygous for various male-sterile chromosomal rearrangements show the same meiotic phenotype: partially asynaptic, rearranged autosomes

Ji?í Forejt

1996-01-01

230

Sterile Gowning Procedures  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into Sterile Gowning Procedures, which teaches the steps for proper sterile gowning and gloving.

2012-10-15

231

Laser-Induced Gas Breakdown --- Modeling of the Onset Plasma from Experimental Observation  

NASA Astrophysics Data System (ADS)

The nominal 7-ns Nd:YAG laser pulse of fundamental wavelength is used to produce argon and nitrogen breakdown at atmospheric pressure. The formation and profile of the initial plasma depends on the breakdown mechanism, which varies with the optical geometry, the type of gas, and the laser pulse condition used. Time-resolved spontaneous emission images of the early plasma are recorded and are used to determine the initial plasma profile required for the computational fluid dynamics modeling of laser-breakdown. Spectroscopic measurements and CFD predictions* are compared for the post-breakdown behavior of the gas. *CFD-ACE, CFD Research Corporation, Huntsville, AL

Qin, Wenhong; Chen, Ying-Ling; Lewis, J. W. L.; Parigger, C.

2000-11-01

232

Quantitative capillary column gas chromatographic method for the determination of glycopyrronium in human plasma.  

PubMed

A new sensitive and selective capillary column gas chromatographic method for the anti-cholinergic agent glycopyrronium bromide in human plasma is described. The procedure involves preliminary ion-pair extraction of the drug into dichloromethane, followed by concentration and analysis of the ion-pair complex by capillary column gas chromatography using a nitrogen-sensitive detector. The method depends on the thermal dequaternisation of the quaternary ammonium compound and can be used to detect 5 ng/ml in a 3-ml plasma sample. The assay procedure has been applied to the determination of the plasma concentration of glycopyrronium after intravenous administration to an anaesthetised patient. PMID:6746811

Murray, G R; Calvey, T N; Williams, N E; Chan, K

1984-06-01

233

Numerical modeling of plasma plume evolution against ambient background gas in laser blow off experiments  

SciTech Connect

Two dimensional numerical modelling based on simplified hydrodynamic evolution for an expanding plasma plume (created by laser blow off) against an ambient background gas has been carried out. A comparison with experimental observations shows that these simulations capture most features of the plasma plume expansion. The plume location and other gross features are reproduced as per the experimental observation in quantitative detail. The plume shape evolution and its dependence on the ambient background gas are in good qualitative agreement with the experiment. This suggests that a simplified hydrodynamic expansion model is adequate for the description of plasma plume expansion.

Patel, Bhavesh G.; Das, Amita; Kaw, Predhiman; Singh, Rajesh; Kumar, Ajai [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2012-07-15

234

Mechanisms of disruptions caused by noble gas injection into tokamak plasmas  

Microsoft Academic Search

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

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

235

Gas Temperature Determination in Argon-Helium Plasma at Atmospheric Pressure using van der Waals Broadening  

SciTech Connect

The use of the van der Waals broadening of Ar atomic lines to determine the gas temperature in Ar-He plasmas, taking into account both argon and helium atoms as perturbers, has been analyzed. The values of the gas temperature inferred from this broadening have been compared with those obtained from the spectra of the OH molecular species in the discharge.

Munoz, Jose; Yubero, Cristina; Calzada, Maria Dolores [Grupo de Espectroscopia de Plasmas, Edificio A. Einstein (C-2), Campus Rabanales, Universidad de Cordoba (Spain); Dimitrijevic, Milan S. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

2008-10-22

236

Interactions of an Electric Arc Plasma with Transverse Magnetic Fields and Gas Flows.  

National Technical Information Service (NTIS)

Interactions of wall-stabilized and free burning arcs with transverse gas flows and magnetic fields perpendicular to the arc axis are studied. The arc plasma is described by the mono-fluid-approximation and the gas flow is assumed to be laminar, i.e. the ...

W. Fucks K. Bartels E. Fischer J. Uhlenbusch

1968-01-01

237

Generation of magnetic seed fields in protogalactic clouds due to plasma-neutral gas friction  

Microsoft Academic Search

We show that plasma - neutral gas friction in a weakly ionized rotating protogalactic system creates magnetic fields of seed field order. For these purposes we present results of 2-fluid simulations. Considering primordial gas clouds, this mechanism yields a magnetic field of the order of 10(-15) G on time scales of 10(6) yr and spatial scales of several hundred parsec.

H. Wiechen; G. T. Birk; H. Lesch

1998-01-01

238

Kinetic Study of Injected Gas Effects On Divertor Plasma Detachment  

Microsoft Academic Search

Divertor plasma detachment is an important operation regime for the modern fusion devices since it can dramatically reduce the plasma energy flux load to the divertor wall. Due to its good performance for energy and impurities transport, the detachment operation regime can prolong the lifetime of the divertor wall, compared with other operation regimes. However, it is very difficult to

Tengfei Tang; Chaofeng Sang; Jizhong Sun; Dezhen Wang

239

Ozone-mist spray sterilization for pest control in agricultural management  

NASA Astrophysics Data System (ADS)

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.

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

240

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

NASA Astrophysics Data System (ADS)

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.

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

2003-06-01

241

Interplay of discharge and gas flow in atmospheric pressure plasma jets  

NASA Astrophysics Data System (ADS)

Interplay of discharge and gas flow in the atmospheric pressure plasma jets generated with three different discharge modes [N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 106, 013308 (2009); N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 108, 033302 (2010)] has been investigated by simultaneous photographing of both plasma plumes and gas flows in the ambient, with the former being visualized by using an optical schlieren system. Gas flow gains a forward momentum from discharge except for the case of overflow jets at smaller applied voltages. Larger applied voltage implies an elongated plasma jet only for single-electrode mode; for dielectric barrier discharge jet the plume length maximizes at a properly applied voltage. These findings can help understand the underlying processes, and are useful particularly for the economic operation of tiny helium plasma jets and jet arrays.

Jiang, Nan; Yang, Jinglong; He, Feng; Cao, Zexian

2011-05-01

242

Gas-phase and sample characterizations of multiwall carbon nanotube growth using an atmospheric pressure plasma  

SciTech Connect

Multiwall carbon nanotubes (CNTs) are synthesized using an atmospheric pressure rf plasma jet, with helium feed gas and acetylene gas as the precursor. The nanotubes are grown on a substrate with a thin catalyst (iron) film, with the substrate placed downstream from the plasma on a copper hot plate. In situ Fourier transformed infrared spectroscopy indicates an increase in gas temperature and a decrease in the density of the acetylene molecules at higher plasma powers. The helium metastables in the plasma break the C-H bonds in acetylene, causing molecular dissociation. It is apparent that the resultant formation of unsaturated carbon bonds causes taller and more graphitized CNT films to grow, as evident from scanning electron microscopy and Raman analyses of the samples. However, at higher substrate temperatures, taller and better quality films are obtained due to enhanced catalytic activity on the substrate surface.

Chandrashekar, Anand; Lee, Jeong-Soo; Lee, Gil S.; Goeckner, Matthew J.; Overzet, Lawrence J. [Department of Electrical Engineering, University of Texas at Dallas, 2301 North Floyd Road, Richardson, Texas 75080 (United States)

2006-09-15

243

Gamma Inert Sterilization: A Solution to Polyethylene Oxidation?  

PubMed Central

Background: In the 1990s, oxidation was found to occur in ultra-high molecular weight polyethylene total joint replacement components following gamma irradiation and prolonged shelf aging in air. Orthopaedic manufacturers developed barrier packaging to reduce oxidation during and after radiation sterilization. The present study explores the hypothesis that polyethylene components sterilized in a low-oxygen environment undergo similar in vivo oxidative mechanisms as inserts sterilized in air. In addition, the potential influence of the different sterilization processes on the wear performance of the polyethylene components was examined. Methods: An analysis of oxidation, wear, and surface damage was performed for forty-eight acetabular liners and 123 tibial inserts. The mean implantation time was 12.3 ± 3.7 years for thirty-one acetabular liners that had been gamma sterilized in air and 4.0 ± 2.5 years for the seventeen acetabular liners that had been gamma sterilized in inert gas. The mean implantation time was 11.0 ± 3.2 years for the twenty-six tibial inserts that had been sterilized in air and 2.8 ± 2.2 years for the ninety-seven tibial inserts that had been gamma sterilized in inert gas. Oxidation and hydroperoxide levels were characterized in loaded and unloaded regions of the inserts. Results: Measurable oxidation and oxidation potential were observed in all cohorts. The oxidation and hydroperoxide levels were regional. Surfaces with access to body fluids were more heavily oxidized than protected bearing surfaces were. This variation appeared to be greater in historical (gamma-in-air-sterilized) components. Regarding wear performance, historical and conventional acetabular liners showed similar wear penetration rates, whereas a low incidence of delamination was confirmed for the conventional tibial inserts in the first decade of implantation. Conclusions: The present study explores the impact of industry-wide changes in sterilization practices for polyethylene. We found lower oxidation and oxidation potential in the conventional acetabular liners and tibial inserts that had been gamma sterilized in inert gas as compared with the historical components that had been gamma sterilized in air. However, we also found strong evidence that conventional components undergo mechanisms of in vivo oxidation similar to those observed following gamma irradiation in air. In addition, gamma sterilization in inert gas did not provide polyethylene with a significant improvement in terms of wear resistance as compared with gamma sterilization in air, except for a lower incidence of delamination in the first decade of implantation for tibial inserts. Clinical Relevance: Our research demonstrates that gamma inert sterilization may have improved, but not completely solved, the problem of polyethylene oxidation for hip and knee arthroplasty.

Medel, Francisco J.; Kurtz, Steven M.; Hozack, William J.; Parvizi, Javad; Purtill, James J.; Sharkey, Peter F.; MacDonald, Daniel; Kraay, Matthew J.; Goldberg, Victor; Rimnac, Clare M.

2009-01-01

244

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

NASA Astrophysics Data System (ADS)

Effects of gas flow rate on the length of atmospheric pressure plasma jets have been investigated using a capillary dielectric barrier discharge configuration. For the discharge in only downstream region, three distinguishable modes of plasma jet length versus argon gas flow rate, namely, laminar, transition, and turbulent jet mode, have been identified. For the case of discharge in both downstream and upstream regions, the curve of length versus flow rate has significant ``dent'' in the laminar jet mode for pure helium, neon, and argon flow gas spraying into air ambient.

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

2009-10-01

245

Synthesis of carbon nanbotubes by plasma-enhanced CVD process: gas phase study of synthesis conditions  

NASA Astrophysics Data System (ADS)

To support experimental investigations, a model based on Chemkin^TM software was used to simulate gas phase and surface chemistry during plasma-enhanced catalytic CVD of carbon nanotubes. According to these calculations, gas phase composition, etching process and growth rates are calculated. The role of several carbon species, hydrocarbon molecules and ions in the growth mechanism of carbon nanotubes is presented in this study. Study of different conditions of gas phase activation sources and pressure is performed.

Guláš, M.; Cojocaru, C. S.; Fleaca, C. T.; Farhat, S.; Veis, P.; Le Normand, F.

2008-09-01

246

Effect of ambient gas and pressure on fullerene synthesis in induction thermal plasma  

Microsoft Academic Search

Fabrication of fullerenes (C60, C70, etc.) by direct evaporation of C–Si mixed powder using radio frequency inductively coupled thermal plasma were made to find a suitable gas kind and pressure for fullerene synthesis. The results showed that: (1) 150 Torr lower pressure and He\\/Ar mixed gas are more suitable for fullerene synthesis than higher pressure and pure Ar gas, and

C. Wang; A Inazaki; T Shirai; Y Tanaka; T Sakuta; H Takikawa; H Matsuo

2003-01-01

247

Cost analysis of three low-temperature sterilization systems at Saint Barnabas Medical Center.  

PubMed

To avoid the heavily increasing costs of ethylene oxide, and with the imminent demise of 88/12 EtO at the same time that heat-sensitive endoscope use was on the rise, Saint Barnabas Medical Center in Livingston, NJ was urgently interested in choosing among low-temperature sterilization alternatives currently available. They decided to compare the costs of 100% EtO with the 88/12 system and a new, low-temperature hydrogen peroxide gas plasma system (HPGP) called STERRAD. The HPGP system proved to be less expensive overall than either EtO system due to quicker total cycle times, lower utility use and virtually no regulatory compliance issues. The hospital was also satisfied that the system effectively sterilized the items on which it was used. PMID:10135488

Chobin, N G

1994-08-01

248

Study Of The Gas Balance By Injection Of Hydrocarbons Into The Plasma Simulator PSI 2  

SciTech Connect

The stationary plasma of the plasma generator PSI 2 is used to study the gas balance of hydrocarbons and hydro-gen by means of mass spectrometers. For this purpose H2, acetylene and ethylene are injected into argon and hydrogen plasmas. It is found that hydrogenation of the hydrocarbon layers is strongly influenced by the hydrocarbon species injected previously. Furthermore, time constants of more than 1000 s for achieving stationary conditions are identified in some cases. The H/C ratio of the hydrocarbon layers is found to vary from about 1 to 1.4 for argon and hydrogen plasmas, respectively.

Bohmeyer, Werner [Max- Planck- Institut fuer Plasmaphysik TI Greifswald, Wendelsteinstr. 1 17491 Greifswald EURATOM Ass. (Germany); Markin, Andrey [RAS, Institute of Physical Chemistry, Moscow (Russian Federation); Koch, Bernd; Fussmann, Gerd [Max- Planck- Institut fuer Plasmaphysik TI Greifswald, Wendelsteinstr. 1 17491 Greifswald EURATOM Ass. (Germany); Humboldt Universitaet zu Berlin, Plasmaphysik, Newtonstr.15 12489 Berlin (Germany); Krenz, Gordon [Humboldt Universitaet zu Berlin, Plasmaphysik, Newtonstr.15 12489 Berlin (Germany)

2006-01-15

249

Numerical analysis of shroud gas effects on air entrainment into thermal plasma jet in ambient atmosphere of normal pressure  

Microsoft Academic Search

A numerical analysis of the influence of air entrainment into the plasma jet on the thermal plasma characteristics is performed to provide a design basis for nontransferred plasma torches operated in an ambient air of atmospheric pressure along with shroud gas injection. The assumption of steady-state, axisymmetric, local thermodynamic equilibrium, and optically thin plasma is adopted in a two-dimensional modeling

Kyoung Doo Kang; Sang Hee Hong

1999-01-01

250

Feed gas humidity: a vital parameter affecting a cold atmospheric-pressure plasma jet and plasma-treated human skin cells  

NASA Astrophysics Data System (ADS)

In this study, the effect of feed gas humidity on the reactive component generation of an atmospheric-pressure argon plasma jet and its effect on human skin cells are investigated. Feed gas humidity is identified as one key parameter that strongly influences stability and reproducibility of plasma medical studies. The plasma jet is investigated by absorption spectroscopy in the ultraviolet and infrared spectral region for its ozone production depending on the humidity concentration in the feed gas. By optical emission spectroscopy the dependence of present excited plasma species such as hydroxyl radicals, molecular nitrogen, argon and atomic oxygen on the feed gas humidity is investigated. As an interface layer between the plasma jet effluent and the biological cell, a buffer solution is treated and the hydrogen peroxide (H2O2) production is studied with two independent colorimetric assays as a function of humidity admixture to the feed gas. Ultimately, the effect of varying feed gas humidity on the cell viability of indirect plasma treated adherent HaCAT cells is investigated. The highest viability is found for the driest feed gas condition. Furthermore, this work shows answers for the relevance of unwanted—or intended—feed gas humidity in plasma medical experiments and their comparatively large relevance with respect to ambient humidity. The findings will lead to more reproducible experiments in the field of plasma medicine.

Winter, J.; Wende, K.; Masur, K.; Iseni, S.; Dünnbier, M.; Hammer, M. U.; Tresp, H.; Weltmann, K.-D.; Reuter, S.

2013-07-01

251

Surface modification of silicone rubber by gas plasma treatment  

Microsoft Academic Search

Silicone rubber films were surface-modified with O2, Ar, or NH3 plasma in either a bell-jar-type or a tubular-type reactor to investigate the effect of the plasma treatment conditions on the hydrophilicity, peel strength, and chemical composition of the film surface. ESCA spectra of the modified films were used to calculate the elemental ratios of oxygen to carbon and nitrogen to

J. Y. Lai; Y. Y. Lin; Y. L. Denq; S. S. Shyu; J. K. Chen

1996-01-01

252

[Investigation on the gas temperature of a plasma jet at atmospheric pressure by emission spectrum].  

PubMed

A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce plasma plume in atmospheric pressure argon. Spatially and temporally resolved measurement was carried out by photomultiplier tubes. The light emission signals both from the dielectric barrier discharge and from the plasma plume were analyzed. Furthermore, emission spectrum from the plasma plume was collected by high-resolution optical spectrometer. The emission spectra of OH (A 2sigma + --> X2 II, 307.7-308.9 nm) and the first negative band of N2+ (B2 sigma u+ --> X2 IIg+, 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The rotational temperature obtained is about 443 K by fitting the emission spectrum from the OH, and that from the first negative band of N2+ is about 450 K. The rotational temperatures obtained by the two method are consistent within 5% error band. The gas temperature of the plasma plume at atmospheric pressure was obtained because rotational temperature equals to gas temperature approximately in gas discharge at atmospheric pressure. Results show that gas temperature increases with increasing the applied voltage. PMID:21284147

Li, Xue-chen; Yuan, Ning; Jia, Peng-ying; Niu, Dong-ying

2010-11-01

253

Global modelling of tank gas density and effects on plasma density control in MAST  

NASA Astrophysics Data System (ADS)

A zero-dimensional, or global, description of fuelling and exhaust processes is introduced to help assess techniques for reducing the density of gas, and its impact on plasma-density control, within the large vacuum tank of the MAST spherical tokamak. Model calculations for sample MAST discharges reveal their typical ion confinement time (<=50 ms) and contrasting fuelling efficiencies for outboard or inboard puffing. In steady state, the ratio between tank molecular and plasma densities is fixed irrespective of any sinks when gas is puffed from the vessel wall, but for fuelling at the plasma edge with moderate ionization efficiency, unsaturated boronization of MAST surfaces can yield ap5 × lower gas density and excellent plasma pump-out. A 'two-chamber' adaptation of the global model with zones connected by variable conductances is also defined to address a possible in-vessel, cryopumped divertor. Exact limiting solutions reveal that for a constant plasma, steady-state gas density in the main torus generally rises for stronger divertor pumping when puffing into the tank, while it only decreases with pumping for fuelling at non-zero efficiency directly into the divertor plasma or 100% efficiency at any location. Full 'two-chamber' calculations for MAST indicate that the tank gas would be lowered principally through high divertor closure and fuelling efficiency, which combined with unsaturated boronization lead to > 10 × less steady gas density. Divertor cryopumping would be useful chiefly for plasma density control in long pulses or sustained exhaust in the absence of wall sinks. Global modelling offers a way similarly to examine fuelling behaviour in any tokamak device.

Maddison, G. P.; Turner, A.; Fielding, S. J.; You, S.

2006-01-01

254

Modeling of gas dynamics for a laser-generated plasma: propagation into low-pressure gases  

PubMed

The physical phenomena involved during three-dimensional axisymmetric laser-induced plasma expansion into background gas are numerically studied. For this purpose, a multispecies hydrodynamic model is developed which considers the effects of mass and ambipolar diffusions, thermal conduction, viscosity, and nonequilibrium conditions for ionization. This model is applied to describe quantitatively the Si plasma plume expansion into Ar or He gases. It is shown that the mechanism of plasma expansion depends critically on both the pressure and mass of the background gas. The shock front expansion is found to be strongly correlated with ion dynamics. A pronounced difference between heavy-particle and electron temperatures indicates a persistent lack of equilibrium between the heavy particle and the electron in the plasma plume expansion. The Si atoms of the rarefied plume are essentially driven by the backward-moving background gas as a result of a mass diffusion process. It is also noted that the diffusion processes are only important in the last expansion stage, and are less significant in the first stage. Therefore, it is shown that a computation which does not include diffusion effects (Euler equations) can adequately describe only the earliest stage of plasma expansion into background gas. The ability of the Navier-Stokes hydrodynamic multispecies model to predict the key role of the background gas type (Ar, He) and pressure is demonstrated. PMID:11088944

Le; Zeitoun; Parisse; Sentis; Marine

2000-09-01

255

Measurements of the potential and current structures of auroral-like plasma terminating on neutral gas  

NASA Astrophysics Data System (ADS)

A unique new plasma source1 large enough so that electrons are not in direct contact with any wall enables, for the first time, a laboratory study of the auroral atmospheric boundary. The 3-D potential and current structures of the quiescent (? n/n <5%), magnetized (dia = 30 ? i) plasma terminating on a neutral gas have been measured and compared to theory. A thermally emissive LaB6 cathode biased <400 V ionizes a background helium gas to make a plasma (L<30 m). The plasma ending on the gas has has no net current, however, complicated auroral-like closed-current structures and drifts exist throughout the system. Hot electrons carry field aligned currents which close by ion cross field Pederson currents. Langmuir and emissive probes are used to measure the plasma electric fields and other basic plasma properties. The 3-D nature of the currents is verified by magnetic probes. A strong field-aligned neutral collision dominated double layer (? ? /kTe ˜ 1) terminates the auroral structure where the plasma pressure matches the neutral gas pressure. In this region, electric fields and neutral-collision dominated conductivities allow comparable cross field and field aligned currents, allowing closure of the current systems. The experiment was carried out at the ETPD at UCLA, a large toroidal device (major radius = 5 m, 2 m wide, 3 m tall) with a pulsed (1 Hz) DC plasma discharge (tdisch ˜20ms, Bt ˜250G, and Bv<6G, Rplasma=10cm, ne<1013cm3, Te<10eV, and Ti ˜ Te). Work funded by the Department of Energy and National Science Foundation and performed at the Basic Plasma Science Facility at UCLA.

Cooper, C. M.; Gekelman, W. N.

2011-12-01

256

GAS6 IN ARDS PATIENTS: DETERMINATION OF PLASMA LEVELS AND INFLUENCE OF PEEP SETTING.  

PubMed

Purpose:Growth arrest-specific protein 6 (Gas6) is a vitamin K-dependent protein expressed by endothelial cells and leukocytes participating in cell survival, migration and proliferation and involved in many pathological situations. The aim of our study was to assess its implication in acute respiratory distress syndrome (ARDS) and its variation according to positive end expiratory pressure (PEEP) setting, considering that different cyclic stresses could alter Gas6 plasma levels.Methods:Our patients were enrolled in the ExPress study comparing a minimal alveolar distension ("low PEEP") ventilatory strategy to a maximal alveolar recruitment ("high PEEP") strategy in ARDS. Plasma Gas 6, IL8 and VEGF levels were measured at day 0 and day 3 by enzyme-linked immunosorbent assay in blood samples prospectively collected during the study for a subset of 52 patients included in 8 centers during year 2005.Results: We found that Gas6 plasma level was elevated in the whole population at day 0: 106 ng/mL (77-139), (median, IQR), with significant correlations with IL8, the Simplified Acute Physiologic Score II and the Organ Dysfunction and Infection (ODIN) scores. Statistically significant decreases in Gas6 and IL 8 plasma levels were observed between day 0 and day 3 in the "high PEEP" group (P=0.017); while there were no differences between day 0 and day 3 in the "low PEEP" group.Conclusion:Gas6 plasma level is elevated in ARDS patients. The "high PEEP" strategy is associated with a decrease in Gas6 and IL8 plasma levels at day 3, without significant differences in day 28 mortality between the 2 groups.Trial registration:clinicaltrials.gov Identifier: NCT00188058. PMID:23571515

Diehl, Jean-Luc; Coolen, Nathalie; Faisy, Christophe; Osman, David; Prat, Gwenael; Sebbane, Mustapha; Nieszkowska, Ania; Gervais, Claude; Richard, Jean-Christophe M; Richecoeur, Jack; Brochard, Laurent; Mercat, Alain; Guérot, Emmanuel; Borgel, Delphine

2013-04-01

257

A gas-puff-driven theta pinch for plasma-surface interaction studies  

NASA Astrophysics Data System (ADS)

DEVeX is a theta pinch device used to investigate fusion-related material interaction such as vapor shielding and ICRF antenna interactions with plasma-pulses in a laboratory setting. The simulator is required to produce high heat-flux plasma enough to induce temperature gradient high enough to study extreme conditions happened in a plasma fusion reactor. In order to achieve it, DEVeX is reconfigured to be combined with gas puff system as gas puffing may reduce heat flux loss resulting from collisions with neutral. A gas puff system as well as a conical gas nozzle is manufactured and several diagnostics including hot wire anemometer and fast ionization gauge are carried out to quantitatively estimate the supersonic flow of gas. Energy deposited on the target for gas puffing and static-filled conditions is measured with thermocouples and its application to TELS, an innovative concept utilizing a thermoelectric-driven liquid metal flow for plasma facing component, is discussed.

Jung, Soonwook; Kesler, Leigh; Yun, Hyun-Ho; Curreli, Davide; Andruczyk, Daniel; Ruzic, David

2012-10-01

258

Mechanisms of gas precipitation in plasma-exposed tungsten  

SciTech Connect

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).

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

2012-05-01

259

Optimized method of producing washers of titanium hydride for plasma gun using occluded hydrogen gas  

NASA Astrophysics Data System (ADS)

An optimized way of producing washers of titanium hydride for the application to a plasma gun using the occluded gas is presented. The amount of H2 gas (equivalently, gas pressure p) is entirely preadjusted in a gas reservoir of a simple instrument. The temperature T of a furnace is completely feedback controlled. Data show that when p is the order of 1 atm, T needs to be higher than about 450 °C in order to successfully produce washers of titanium hydride. Results on compressive strength of the loaded washers suggest that an appropriate ratio of atoms of hydrogen to titanium is less than H:Ti~0.85:1.

Himura, H.; Saito, Y.; Sanpei, A.; Masamune, S.; Takeuchi, N.; Shiono, T.

2006-07-01

260

Potential and current structures of auroral-like plasma terminating on neutral gas  

NASA Astrophysics Data System (ADS)

The 3-D potential and current structures of a quiescent (?n/n <5%), magnetized plasma terminating on a neutral gas have been measured and compared to theory. A thermally emissive LaB6 cathode biased <400 V ionizes a background helium gas. The 30 m plasma is not terminated by an electrode so there are no net currents in it. There are, however, complicated auroral-like closed-current structures. Hot electrons carry a field aligned currents and ions carry a cross field current to closure currents in the low density plasma halo around the plasma. Probes are used to measure the plasma's electric fields, currents, and basic plasma properties. A strong field-aligned neutral collision dominated double layer (??/kTe ˜ 1) terminates the auroral structure where the plasma pressure matches the neutral pressure. In this region, electric fields and neutral-collision dominated conductivities create comparable cross field and field aligned currents, closing the current loop. The experiment was carried out at the ETPD at UCLA, a large toroidal device (major radius = 5 m, 2 m wide, 3 m tall) with a pulsed (1 Hz) DC plasma discharge (td˜20 ms, Bt˜250 G, and Bv<6G, Rplasma=10cm, ne<10^13cm^3, Te<10eV, and Ti˜Te).

Cooper, Christopher; Gekelman, Walter

2011-11-01

261

Magnetically controlled deposition of metals using gas plasma. Final report  

SciTech Connect

This 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 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 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. This report contains the results of the computer code that have been completed to date. Results from a ASMEE Benchmark problem, flow over a backward step with heat transfer, Couette flow with magnetic forces, free jet flow are presented along with several other check calculations that are representative of the cases that were calculated in the course of the development process. The final cases that define a velocity field in the exit of a plasma spray torch with and without a magnetic field are in process. A separate program (SPRAY) has been developed that can track the plating material to the substrate and describe the distribution of the material on the substrate. When the jet calculations are complete SPRAY will be used to compare the distribution of material on the substrate with and without the effect of the magnetic focus.

NONE

1998-04-02

262

A soliton gas model for astrophysical magnetized plasma turbulence  

NASA Astrophysics Data System (ADS)

Plasma turbulence is considered as an ensemble of solitons. The derivation of the Alfven soliton by Spangler and Sheering (1981) is reviewed, and expressions are derived for the magnetic irregularity spectrum and the relationship between the magnetic and density irregularity power spectra. A derived expression also provides the answer to the question of the correlation between magnetic field and density enhancements. The properties of the turbulence model are compared with observations of plasma turbulence in the solar wind, and are found to reasonably account for them.

Spangler, S. R.; Sheerin, J. P.

1982-06-01

263

Sterile neutrinos and RK  

NASA Astrophysics Data System (ADS)

We consider an enhancement in the violation of lepton flavour universality in light meson decays arising from modified Wl? couplings in the standard model minimally extended by sterile neutrinos. Due to the presence of additional mixings between the active neutrinos and the new sterile states, the deviation from unitarity of the leptonic mixing matrix intervening in charged currents might lead to a tree-level enhancement of RP = ?(P ? ev)/?(P ? ??), with P = K, ?. These enhancements are illustrated in the case of the inverse seesaw, showing that one can saturate the current experimental bounds on ?rK (and ?r?), while in agreement with the different experimental and observational constraints.

Vicente, A.

2013-07-01

264

Charge exchange of multiply charged laser plasma ions with rare-gas jet atoms  

SciTech Connect

The interaction of a gas jet (He, Ne, Xe) with the incident laser plasma from a solid target [B, (CH{sub 2}){sub n}, (CF{sub 4}){sub n}] removed by {approx}1 cm is investigated. Line spectra arising from the charge exchange of multiply charged plasma ions with rare-gas atoms are recorded in the multiply charged ions-gas interaction region. The ratios between the partial cross sections of the charge exchange with the production of these ions in excited states are determined from the relative intensities of the Balmer series transitions in BV and CVI ions. These results are compared with theoretical data. (interaction of laser radiation with matter. laser plasma)

Beigman, I L; Levashov, V E; Mednikov, K N; Pirozhkov, A S; Ragozin, E N; Tolstikhina, I Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2007-11-30

265

Generation and confinement of microwave gas-plasma in photonic dielectric microstructure.  

PubMed

We report on a self-guided microwave surface-wave induced generation of ~60 ?m diameter and 6 cm-long column of argon-plasma confined in the core of a hollow-core photonic crystal fiber. At gas pressure of 1 mbar, the micro-confined plasma exhibits a stable transverse profile with a maximum gas-temperature as high as 1300 ± 200 K, and a wall-temperature as low as 500 K, and an electron density level of 1014 cm-3. The fiber guided fluorescence emission presents strong Ar+ spectral lines in the visible and near UV. Theory shows that the observed combination of relatively low wall-temperature and high ionisation rate in this strongly confined configuration is due to an unprecedentedly wide electrostatic space-charge field and the subsequent ion acceleration dominance in the plasma-to-gas power transfer. PMID:24150390

Debord, B; Jamier, R; Gérôme, F; Leroy, O; Boisse-Laporte, C; Leprince, P; Alves, L L; Benabid, F

2013-10-21

266

A platform for highly charged ions: surface-foil-gas-plasma interaction at the IMP  

NASA Astrophysics Data System (ADS)

A platform for the study of highly charged ions (HCIs), the surface-foil-gas-plasma interaction at IMP Lanzhou, is introduced. Some potentially useful results obtain over the last few years on x-ray emission, ion sputtering, secondary electron emission and the nano-etching effects during HCIs' impact on surfaces, as well as the guiding effect of nano-capillaries, are reviewed. Our ongoing work on the HCI interaction with plasma is also reported.

Cheng, R.; Zhou, X. M.; Sun, Y. B.; Lei, Y.; Wang, X.; Xu, G.

2011-06-01

267

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

Microsoft Academic Search

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

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

2002-01-01

268

Self-sustained plasma waveguide structures produced by ionizing laser radiation in a dense gas  

Microsoft Academic Search

The propagation of high-power laser radiation producing rapid ionization in a dense gas is analyzed by using a nonlinear electrodynamical model. It is shown that the interplay between the Kerr-type and the defocusing ionization nonlinearities may lead to the formation of self-sustained plasma waveguide filaments. Quasi-steady-state laser-plasma structures supported by various electromagnetic field configurations are considered.

D. Anderson; A. V. Kim; M. Lisak; V. A. Mironov; A. M. Sergeev; L. Stenflo

1995-01-01

269

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

DOEpatents

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.

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

270

Modeling of gas discharge plasmas: What can we learn from it?  

Microsoft Academic Search

This paper describes some of our modeling efforts for gas discharges, used for plasma surface engineering applications. Depending on the application, we use either a fluid approach or particle-in-cell—Monte Carlo (PIC—MC) models to simulate the plasma behavior. The examples shown in this paper include fluid modeling for nanoparticle formation in silane discharges and for nitrogen dielectric barrier discharges, as well

Annemie Bogaerts; Kathleen De Bleecker; Ivan Kolev; Myriam Madani

2005-01-01

271

Fast plasma shutdown scenarios in the JT-60U tokamak using intense mixed gas puffing  

Microsoft Academic Search

Fast plasma shutdown without runaway electron generation by gas puffing is investigated in the JT-60U tokamak. Argon-only injection enables a fast shutdown; however, it induces runaway electron generation. Hydrogen-only injection generates much less runaway electrons; however, the shutdown time is considerably longer. Mixed injection of hydrogen and argon achieves a fast plasma shutdown without runaway generation. Argon atoms contribute to

M. Bakhtiari; Y. Kawano; H. Tamai; Y. Miura; R. Yoshino; Y. Nishida

2002-01-01

272

Simulation of High Power THz Emission from Laser Interaction with Tenuous Plasma and Gas Targets  

Microsoft Academic Search

With one- and two-dimensional particle-in-cell (PIC) codes, we simulate the generation of high power terahertz (THz) emission from the interaction of ultrashort intense lasers with tenuous plasma and gas targets. By driving high-amplitude elec- tron plasma waves either with a laser wakefield or the beatwave of two laser pulses, powerful THz electromagnetic pulses can be produced by linear mode conversion

Zheng-Ming Sheng; Hui-Chun Wu; Wei-Min Wang; Min Chen; Xiao-Gang Dong; Jun Zheng; Jie Zhang

2008-01-01

273

Gas Tungsten Arc Welding and Plasma Arc Cutting. Teacher Edition.  

ERIC Educational Resources Information Center

This welding curriculum guide treats two topics in detail: the care of tungsten electrodes and the entire concept of contamination control and the hafnium electrode and its importance in dual-air cutting systems that use compressed shop air for plasma arc cutting activities. The guide contains three units of instruction that cover the following…

Fortney, Clarence; And Others

274

Kinetics in Gas Mixtures for Problem of Plasma Assisted Combustion.  

National Technical Information Service (NTIS)

Throughout the whole period of the research we performed the following tasks: The current state of the art in approaches to the study of kinetics of plasma assisted combustion and ignition has been reviewed. It was demonstrated that, in spite of a large b...

S. Starikovskaia

2010-01-01

275

Gas Tungsten Arc Welding and Plasma Arc Cutting. Teacher Edition.  

ERIC Educational Resources Information Center

|This welding curriculum guide treats two topics in detail: the care of tungsten electrodes and the entire concept of contamination control and the hafnium electrode and its importance in dual-air cutting systems that use compressed shop air for plasma arc cutting activities. The guide contains three units of instruction that cover the following…

Fortney, Clarence; And Others

276

Particle and Gas Velocity Measurements in a DC Plasma Jet.  

National Technical Information Service (NTIS)

Measurements were made, using Laser Doppler Anemometry (LDA), of the velocity of 53 mu m alumina particles as they are injected in a dc plasma jet operated with an argon-nitrogen mixture (18.9 l/min argon and 4.7 l/min nitrogen) at a power level of 15.2 k...

J. Lesinski B. Mizera-Lesinska J. Jurewicz M. I. Boulos

1980-01-01

277

Evaluation of Water Sterilizing Tablets.  

National Technical Information Service (NTIS)

Water sterilizing tablets were evaluated for efficiency of kill of micro-organisms, effect of inhibitors and palatability. The effect of long term use is discussed. The water sterilizing tablet recommended for disinfection of personal drinking water, on t...

G. F. Thomson K. W. James G. E. Driver A. T. Hancock

1985-01-01

278

Hybrid sterility in the mouse.  

PubMed

The sterility of hybrids between various mouse species follows Haldane's rule by affecting only the males. Hitherto, five hybrid sterility (Hst) loci have been identified in the mouse genome. Haldane's rule holds also for chromosomal sterility in all studied mammalian species, including man. The males heterozygous for various male-sterile chromosomal rearrangements show the same meiotic phenotype: partially asynaptic, rearranged autosomes associate with the X Chromosome. Thus, the X-Chromosome inactivation in the male meiosis might function as a checkpoint leading to the meiotic arrest in sterile hybrids. Chromosomal and gene hybrid sterility might be interrelated because the attributes of chromosomal sterility, such as X-autosome associations, occur also in interspecies hybrids with genic sterility. PMID:8909138

Forejt, J

1996-10-01

279

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

DOEpatents

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.

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

280

Gynaecological Illness after Sterilization  

PubMed Central

A total of 374 patients were followed up for at least 10 years after tubal ligation, and 43% required further gynaecological treatment. Major gynaecological surgery was needed by 25%. There seems a good case for the selective use of hysterectomy as a method of sterilization.

Muldoon, M. J.

1972-01-01

281

Hierarchically acting sterile neutrinos  

NASA Astrophysics Data System (ADS)

We propose that a hierarchical spectrum of sterile neutrinos (eV, keV, 1013-15 GeV) is considered as the explanation for MiniBooNE and LSND oscillation anomalies, dark matter, and baryon asymmetry of the universe (BAU), respectively. The scenario can also realize the smallness of active neutrino masses by the seesaw mechanism.

Chen, Chian-Shu; Takahashi, Ryo

2012-07-01

282

MINOS Sterile Neutrino Search  

SciTech Connect

The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline accelerator neutrino experiment designed to measure properties of neutrino oscillation. Using a high intensity muon neutrino beam, produced by the Neutrinos at Main Injector (NuMI) complex at Fermilab, MINOS makes two measurements of neutrino interactions. The first measurement is made using the Near Detector situated at Fermilab and the second is made using the Far Detector located in the Soudan Underground laboratory in northern Minnesota. The primary goal of MINOS is to verify, and measure the properties of, neutrino oscillation between the two detectors using the {nu}{sub {mu}} {yields} V{sub {tau}} transition. A complementary measurement can be made to search for the existence of sterile neutrinos; an oft theorized, but experimentally unvalidated particle. The following thesis will show the results of a sterile neutrino search using MINOS RunI and RunII data totaling {approx}2.5 x 10{sup 20} protons on target. Due to the theoretical nature of sterile neutrinos, complete formalism that covers transition probabilities for the three known active states with the addition of a sterile state is also presented.

Koskinen, David Jason; /University Coll. London

2009-09-01

283

Feather-like He plasma plumes in surrounding N2 gas  

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

284

Evolution dynamics of a dense frozen Rydberg gas to plasma  

NASA Astrophysics Data System (ADS)

Dense samples of cold Rydberg atoms have previously been observed to spontaneously evolve to a plasma, despite the fact that each atom may be bound by as much as 100cm-1 . Initially, ionization is caused by blackbody photoionization and Rydberg-Rydberg collisions. After the first electrons leave the interaction region, the net positive charge traps subsequent electrons. As a result, rapid ionization starts to occur after 1?s caused by electron-Rydberg collisions. The resulting cold plasma expands slowly and persists for tens of microseconds. While the initial report on this process identified the key issues described above, it failed to resolve one key aspect of the evolution process. Specifically, redistribution of population to Rydberg states other than the one initially populated was not observed, a necessary mechanism to maintain the energy balance in the system. Here we report new and expanded observations showing such redistribution and confirming theoretical predictions concerning the evolution to a plasma. These measurements also indicate that, for high n states of purely cold Rydberg samples, the initial ionization process which leads to electron trapping is one involving the interactions between Rydberg atoms.

Li, Wenhui; Noel, Michael W.; Robinson, Michael P.; Tanner, Paul J.; Gallagher, Thomas F.; Comparat, Daniel; Laburthe Tolra, Bruno; Vanhaecke, Nicolas; Vogt, Thibault; Zahzam, Nassim; Pillet, Pierre; Tate, Duncan A.

2004-10-01

285

Evolution dynamics of a dense frozen Rydberg gas to plasma  

SciTech Connect

Dense samples of cold Rydberg atoms have previously been observed to spontaneously evolve to a plasma, despite the fact that each atom may be bound by as much as 100 cm{sup -1}. Initially, ionization is caused by blackbody photoionization and Rydberg-Rydberg collisions. After the first electrons leave the interaction region, the net positive charge traps subsequent electrons. As a result, rapid ionization starts to occur after 1 {mu}s caused by electron-Rydberg collisions. The resulting cold plasma expands slowly and persists for tens of microseconds. While the initial report on this process identified the key issues described above, it failed to resolve one key aspect of the evolution process. Specifically, redistribution of population to Rydberg states other than the one initially populated was not observed, a necessary mechanism to maintain the energy balance in the system. Here we report new and expanded observations showing such redistribution and confirming theoretical predictions concerning the evolution to a plasma. These measurements also indicate that, for high n states of purely cold Rydberg samples, the initial ionization process which leads to electron trapping is one involving the interactions between Rydberg atoms.

Li Wenhui; Noel, Michael W.; Robinson, Michael P.; Tanner, Paul J.; Gallagher, Thomas F.; Comparat, Daniel; Laburthe Tolra, Bruno; Vanhaecke, Nicolas; Vogt, Thibault; Zahzam, Nassim; Pillet, Pierre; Tate, Duncan A. [Department of Physics, University of Virginia, McCormick Road, Charlottesville, Virginia 22903 (United States); Laboratoire Aime Cotton, CNRS II Campus d'Orsay, 91405 Orsay Cedex (France); Department of Physics and Astronomy, Colby College, Waterville, Maine 04901 (United States)

2004-10-01

286

Fast hydrogen gas injection system for plasma physics experiments.  

PubMed

A system has been developed for fast injection of hydrogen gas into a vacuum system, which can produce feedback controlled flows in the range 0.1-10 Torr l/s. The unit uses a fast pressure transducer as a flow sensor. The flow will respond to an external programming voltage whose time variation is as short as several milliseconds. PMID:18699231

Burrell, K H

1978-07-01

287

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Percolation upon expansion of nanosecond-pulse-produced laser plasma into a gas  

NASA Astrophysics Data System (ADS)

Spectral studies of a plasma expanding into the ambient gas upon ablation of various targets by nanosecond laser pulses of moderate intensities are performed. It is found that the dependences of the intensities of spectral lines on the pressure of the buffer gas and the target composition have a threshold character typical of percolation. It is ascertained that a three-dimensional percolation occurs in plasma, and its threshold is determined by the atomic density of the metal component contained in the target. It is shown that percolation clusters, existing at temperatures higher than the boiling temperature of the target material, affect the plasma absorption ability, temperature, and spectral continuum of plasma emission.

Kask, Nikolai E.; Michurin, Sergei V.; Fedorov, Gennadii M.

2005-01-01

288

Plasma gas-switching method for gas chromatography/inductively coupled plasma mass spectrometry and determination of polybrominated diphenylethers with high precision and sensitivity.  

PubMed

The drift in sensitivity due to carbon deposition on the sampling cone, skimmer cone and ion lenses has been a serious problem in gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS). To overcome this problem, a high-speed switching method between a mixed-gas plasma and a pure-argon plasma (named plasma gas-switching method) using an oxygen permeation tube and a switching valve was developed. This enabled both the cleaning of deposited carbon and an enhancement of the sensitivity; as a consequence, both the repeatability and the sensitivity of polybrominated diphenylether (PBDE) were improved by more than 3 and 4 times, respectively. The drifts of sensitivity over a period of 8 h were less than 5% in most cases. Concerning the analytical performance of thermally labile congeners from octa- to deca-BDE, the detection limits, dynamic ranges of the calibration graphs and unequivalent sensitivities were remarkably improved by using a metal capillary separation column coated with a very thin (0.05 micromm) film of immobilized-polydimethylsiloxane. The detection limits ranged from 0.014 pg (BDE-154) to 0.093 pg (BDE-209), which were equal or superior to the lowest values reported hitherto by GC/MS (high resolution). A remarkable loss of sensitivity for highly-brominated congeners, such as nona- and deca-BDE, was observed in an analysis of PBDE technical mixtures when the solvent was methanol. The loss of sensitivity turned out to be due to an activation of the retention gap used for on-column injection; this problem was solved by changing methanol to isooctane in the sample-preparation step before analysis. PMID:19075460

Tao, Hiroaki; Nakazato, Tetsuya; Akasaka, Mikio; Rajendran, Ramaswamy Babu; Elouali, Sofia

2008-12-01

289

Effects of Discharge Current and Gas Flow Rate on CF4 Abatement Process by Thermal Plasma Decomposition  

Microsoft Academic Search

Perfluorocompounds (PFCs) have been widely used in semiconductor and display industry for wafer etching and chamber cleaning processes. However, it is well known that PFCs are serious global warming gases. Although thermal plasma can efficiently decompose a significant quantity of waste gas, it has demerits of large consumption of electric input power and plasma forming gas in order to commercialize

Sooseok Choi; Hyun Seok Lee; Jun Seok Nam; Woo Seok Kang; Sang Hee Hong

2007-01-01

290

Sterile versus nonsterile clean dressings  

PubMed Central

BACKGROUND Many patients cannot afford sterile dressings. In St John, New Brunswick, clean dressings have been used instead of sterile dressings for years, with no apparent ill effects. No previous studies have compared the sterility and cost of clean versus sterile dressing materials. OBJECTIVES The goals of the present study were to answer the following questions: how much more sterile are sterile dressings than clean dressings; and how much does this extra sterility cost? METHODS Sterility and cost of sterile gauze, panty liners, sanitary napkins, diapers and Coban tape (3M, USA) were compared. Samples, 2 cm × 2 cm in size, were cut out of each material under aseptic conditions, and delivered to the microbiology laboratory in sterile urine containers. The samples were then cultured and organisms were identified using conventional means. RESULTS The cost for one month, using one 20 cm × 5 cm wound dressing daily, was calculated and compared with panty liners ($2.43), sanitary napkins ($5.55), diapers ($9.39) and Coban tape ($0.66), which were much cheaper than sterile dressings ($16.50). How sterile were the dressings? None of the 20 sanitary napkins grew bacteria, one of the 20 panty liners grew bacteria (coagulase-negative Staphylococcus), two of 20 sterile dressings grew bacteria (one coagulase-negative Staphylococcus and one nonhemolytic Streptococcus), 15 of 20 diapers grew bacteria (all bacillus) and two of five Coban rolls grew bacteria (one bacillus and one coagulase-negative Staphylococcus). CONCLUSION The panty liners, sanitary napkins and Coban tape studied were cheaper than, and had a comparible sterility with, the sterile gauze examined.

Alqahtani, Moraya; Lalonde, Donald H

2006-01-01

291

New self-consistent quasistatic approximation for screening and plasma dispersion in the electron gas  

Microsoft Academic Search

A new self-consistent quasistatic screening approach is proposed for studying the properties of an interacting electron gas. The compressibility divergence and the ferromagnetic instability found in the static unscreened Hartree-Fock approximation are nonexistent in this scheme. A better fit to the experimental data on the plasma dispersion relation than the existing calculations for free-electron metals is obtained.

B. Sriram Shastry; Sudhanshu S. Jha; A. K. Rajagopal

1974-01-01

292

Development of a Plasma Sprayed Ceramic Gas Path Seal for High Pressure Turbine Applications.  

National Technical Information Service (NTIS)

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 g...

L. T. Shiembob

1977-01-01

293

Gas-surface dynamics and charging effects during plasma processing of semiconductors  

Microsoft Academic Search

This thesis work attempts to elucidate the fundamentals of gas-surface interactions that occur during plasma etching. Controlled experiments using hyperthermal fluorine beams have enabled us to uncover the scattering dynamics at complex surfaces similar to those encountered in etching. By analyzing energy and angular distributions of inelastically scattered F atoms, we were able to distinguish single- and multiple-bounce scattering and

Gyeong Soon Hwang

1999-01-01

294

Parametric studies of two-color ultrafast terahertz generation in gas plasma filaments  

Microsoft Academic Search

Summary form only given. Previous studies have demonstrated the preponderance of intense ultrafast terahertz (THz) sources based on two-color gas plasma filaments with extremely broad bandwidths in excess of 70 THz. Applications ranging from nonlinear THz materials science to broadband hyperspectral detection drive the need for such sources to be optimized for output power and spectral content. Further, it would

G. Rodriguez; G. L. Dakovski

2010-01-01

295

Outpatient laparoscopic sterilization.  

PubMed

This is a report on a pilot study conducted in Malaysia of outpatient sterilization utilizing laparoscopic technique under local anesthesia and sedation. The preliminary report based on 305 patients is presented with emphasis on the advantages and possible weaknesses of such procedure. Sterilization is performed in the Family Planning Specialist Center, Maternity Hospital. Patients are motivated towards sterilization during the immediate postpartum period in the Maternity Hospital and are counseled regarding the actual procedure. The mean age of the 305 patients was 32.08 years; the mean gravidity was 4.92; and the mean parity was 4.57. The majority of the patients came from the lower social strata with low educational attainment and low income. 253 cases of sterilizations were performed by laparoscopic procedures and 43 cases by minilaparotomy. In 9 cases difficulty was encountered with laparoscopy and subsequently the minilaparotomy was used. The majority of cases seemed to tolerate the sedation and local anesthesia fairly well and without much complaint of pain. Only a very small number of patients complained of pain particularly at the time when the Fallope or Lay rings were applied to the fallopian tubes. The overall complication rate was 14 (4.9%) and of these mild wound sepsis accounted for 6 (1.96%). Most of the wound sepsis was very mild and healed very quickly on daily dressing. No cases of pelvic sepsis were reported. There were 3 cases of uterine perforation by the uterine elevator. There were 2 cases where the fallopian tubes were traumatized and some degree of bleeding occurred. The bleeding was easily controlled by applying another Fallope ring. 2 patients had vomiting during the laparoscopic procedure. There were 7 cases of failed sterilization. 6 of the cases were performed by a trainee registrar in obstetrics and gynecology. The last was performed by a specialist gynecologist. Most of the failures were due to wrong application of rings. The cost per patient was estimated to be around 20 ringgit for a pair of tubal rings, anesthetic agents and suture materials. This preliminary study showed that female sterilization could be done easily as an outpatient procedure. PMID:6459518

Hamid Arshat; Yuliawiratman

1981-03-01

296

Development of a two-stage light gas gun to accelerate hydrogen pellets to high speeds for plasma fueling applications  

Microsoft Academic Search

The development of a two-stage light gas gun to accelerate hydrogen isotope pellets to high speeds is under way at Oak Ridge National Laboratory. High velocities are desirable for plasma fueling applications, since the faster pellets can penetrate more deeply into large, hot plasmas and deposit atoms of fuel directly in a larger fraction of the plasma volume. In the

S. K. Combs; S. L. Milora; C. R. Foust; M. J. Gouge; D. T. Fehling; D. O. Sparks

1988-01-01

297

Development of a two-stage light gas gun to accelerate hydrogen pellets to high speeds for plasma fueling applications  

Microsoft Academic Search

The development of a two-stage light gas gun to accelerate hydrogen isotope pellets to high speeds is under way at Oak Ridge National Laboratory. High velocities (>2 km\\/s) are desirable for plasma fueling applications, since the faster pellets can penetrate more deeply into large, hot plasmas and deposit atoms of fuel directly in a larger fraction of the plasma volume.

S. K. Combs; S. L. Milora; C. R. Foust; M. J. Gouge; D. T. Fehling; D. O. Sparks

1989-01-01

298

Formation of a hydrogen plasma from an incandescently heated hydrogen-catalyst gas mixture with an anomalous afterglow duration  

Microsoft Academic Search

We report the generation of a plasma of hydrogen and certain alkali ions as recorded via EUV spectroscopy and the hydrogen Balmer and alkali line emissions in the visible range. Typically, a hydrogen plasma is generated and the emission of extreme ultraviolet light from hydrogen gas is achieved via a discharge at high voltage, a high power inductively-coupled plasma, or

Randell L. Mills; Takeyoshi Onuma; Ying Lu

2001-01-01

299

Measurement of plasma production and neutralization in gas neutralizers  

SciTech Connect

In order to satisfy the need of experimental data for the designing of gas neutralizers we have started a project aimed at measuring all relevant cross sections for the charge exchange of H/sup -/, H/sup 0/ and H/sup +/ projectiles, as well as the cross sections for the production of ions in the target. The expected results of these latter measurements are shown schematically.

Maor, D.; Meron, M.; Johnson, B.; Jones, K.; Agagu, A.; Hu, B.

1986-06-17

300

Investigation of a Gas Jet-Produced Hollow Plasma Wakefield Accelerator  

SciTech Connect

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.

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

2009-05-21

301

Determination of acenocoumarol in human plasma by capillary gas chromatography with mass-selective detection.  

PubMed

A method for the determination of acenocoumarol in human plasma by capillary gas chromatography-mass-selective detection is described. After addition of a structurally related analogue as the internal standard, the compounds are extracted from plasma at acidic pH into toluene, back-extracted with a basic solution and re-extracted from hydrochloric acid solution with toluene, which is then evaporated to dryness. The compounds are converted into their methyl derivatives, which are determined by gas chromatography using a mass-selective detector at m/z 324 for acenocoumarol and m/z 338 for the internal standard. The reproducibility and accuracy of the method were found to be suitable over the acenocoumarol concentrations range 2.2-74 nmol/l. The method could be considered as selective for acenocoumarol in the presence of its major metabolites in plasma. PMID:8004241

Pommier, F; Ackermann, R; Sioufi, A; Godbillon, J

1994-03-18

302

Spiral Galaxy Model with Axial Plasma/Gas Vortex: A Possible Suggestion  

NASA Astrophysics Data System (ADS)

From the measured rotational velocity profiles of spiral galaxies, there appears a central ``core'' with zero central velocity that increases quickly with distance (˜15% of galactic radius) to large constant velocity. This data implies a large centrifugal hydrodynamic force suggesting the ``core'' is a central axial plasma/gas vortex with the following features. (1) MINIMUM central Pressure/Density of Plasma/Gas. (2) Axial Vortex which is manifested as the observed axial Galactic Jets? (3) MAXIMUM central light intensity due to high temperature of energetic central axial vortex? Extensions of the model follow. (1) Matter is sucked into the Galactic Center by the Central Axial Vortex, and that matter is expelled via the central axial galactic jets in dynamic equilibrium over long time scale? (2) No galactic black holes? This vortex model does not address many other important issues such as Dark Matter, galactic evolution, plasma effects, galactic stability, relativistic effects, spiral details, galactic clusters, etc.

Gallo, C. F.

2007-04-01

303

3D Modeling of Laser Propagation in Ionizing Gas and Plasma  

NASA Astrophysics Data System (ADS)

The interaction of a high intensity laser with ionizing gas and plasmas is of current interest for both Laser Wakefield Accelerators and x-ray generation. We have developed a 3D fluid simulation code based on the same quasistatic approximation used in the 2D code WAKE [1]. The object oriented structure of the code also allows it to couple to the quickPIC particle code [2]. We will present 3D studies of the ionization scattering instability [3], which occurs when a laser pulse propagates in an ionizing gas. [1] P. Mora and T. Antonsen, Jr., Phys. Plasmas 4(1), January 1997 [2] J. Cooley, T. Antonsen, Jr., C. Huang, etal., Proceedings, Advanced Accelerator Concepts, 2002 [3] Z. Bian and T. Antonsen, Jr., Phys. Plasmas 8(7), July 2001 * work supported by NSF and DOE

Cooley, J.; Antonsen, T., Jr.; Huang, C.; Mori, W.

2003-10-01

304

Numerical simulation and experimental verification of gas streams feeding a gliding discharge plasma reactor  

NASA Astrophysics Data System (ADS)

The modular device for the waste utilization, using the pyrolytic-plasma method, consists of, among others, the plasma reactor operating on the gliding discharge principles. The reactor is applied to oxidize hydrocarbons created in the process of the waste pyrolysis. Thus, the plasma reactor operation influences significantly the qualitative and quantitative composition of the output gases. Finding the most advantageous construction of the plasma reactor and the process parameters ensures full and complete oxidation of hydrocarbons. In the waste utilization process, two streams of gases were introduced into the plasma reactor through the system of two coaxial nozzles. The first stream was a mixture of argon and hydrocarbons and the second one was oxygen. Two different methods of gas introduction were considered. Methane was used as a model hydrocarbon both in calculations and in the experiments. On the basis of numerical calculations (Fluent commercial program), it was found that the most advantageous method of gas introduction into the reactor was the one in which the mixture of argon and hydrocarbons was introduced through the central nozzle and the oxygen was introduced through the outer one. This conclusion was confirmed experimentally. 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.

Opali?ska, Teresa; Majdak, Ma?gorzata; Piechna, Janusz; Selerowicz, Witold; Wnek, Bart?omiej

2013-02-01

305

Determination of levamisole in plasma and animal tissues by gas chromatography with thermionic specific detection.  

PubMed

A rapid and sensitive method has been developed for the determination of the anthelmintic levamisole in plasma and tissues from man and animals. The procedure involves the extraction of the drug and its internal standard from the biological material at alkaline pH, back-extraction into sulphuric acid and re-extraction into the organic phase (heptane-isoamyl alcohol). Several extraction steps can be omitted, however, whenever the gas chromatographic background permits and some operations can be simplified using Clin ElutTM extraction tubes. The analyses were carried out by gas chromatography using a nitrogen-selective thermionic specific detector. The detection limit was 5 ng, contained in 1 ml of plasma or in 1 g of the various tissues, and recoveries were sufficiently high (79-86%). The method was applied to human plasma samples in a comprehensive bioavailability study of levamisole in healthy volunteers, and to plasma and tissues in a residue trial in cattle. The effect of the blood collection technique on the plasma levels was also studied and pointed to decreased plasma concentrations when Vacutainer tubes were used. PMID:7263817

Woestenborghs, R; Michielsen, L; Heykants, J

1981-06-12

306

Models of Gas-phase and Surface Chemistry for Plasma Enhanced Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Plasma enhanced chemical vapor deposition for inter-metal-layer gap-fill processes are increasingly important in semiconductor device manufacture, as the devices include increasing numbers of metal layers with decreasing linewidth and spacing. Optimization of these processes requires knowledge of the microscopic consequences of variations in reactor operating conditions. Topographical simulation can address the gap-fill performance of a depositing film, but the predictive capabiliities are limited by the ability of the model user to accurately supply ion and radical fluxes at a gas/surface interface. Critical to determining this information are the chemical kinetics between gas-phase species and the deposition surfaces. Recent improvements and extensions to the CHEMKIN and Surface CHEMKIN software allow general inclusion of detailed chemical mechanisms in plasma simulations and in models of plasma-surface interactions. In the results presented here (This work represents a collaboration with R. Larson and P. Ho at Sandia, J. Rey and J. Li at TMA, S. M. Han and E. Aydil of UCSB, and S. Huang at Lam Research Corporation), we have used a CHEMKIN-based well mixed reactor model of a high-density SiH_4/O_2/Ar plasma to predict and characterize species fluxes, oxide-deposition rates, and ion-milling rates on a flat surface. These calculated rates can be used as direct input to a topographical simulator. The gas-phase chemistry in the plasma reactor model is comprised of electron impact reactions with silane, oxygen, hydrogen, and argon, as well as neutral radical recombination, abstraction, and oxidation reactions. The surface reaction mechanism contains four classes of reactions: silicon-containing radical deposition, radical abstraction, ion-induced desorption, and physical ion sputtering. We include relative thermochemistry of the surface and gas species to allow reversible reaction dynamics. The plasma model results show good agreement with measured ion densities, as well as with measured net deposition rates.

Meeks, Ellen

1996-10-01

307

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

SciTech Connect

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.

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

1997-09-01

308

Plasma-melting and plasma-melt-gas-atomization of high temperature intermetallic compounds (Nb3Al)  

NASA Astrophysics Data System (ADS)

There has been much interest in rapidly solidified niobium-aluminides (Nb3Al) as structural materials for ultrahigh temperature applications. Pressurizing melting atmosphere to approximately 0.25 MPa can reduce Al vaporization during plasma melting. A unique plasma-melt-gas-atomization process (PMGA) has been developed for making rapidly-solidified powder of high temperature intermetallic compounds such as Nb3Al. In this technique, we use only water-cooled copper as a tundish for bottom poring, instead of refractories or refractory metals. The crystal structure of PMGA'ed Nb3Al powder consists of an almost Al-saturated solid solution of niobium (bcc). This fact means that the solidification rate of PMGA is sufficiently high.

Kohno, T.; Kohmoto, H.; Murahashi, N.

309

[Permanent tubal hysteroscopic sterilization].  

PubMed

Tubal sterilization, of common practice all over the world, has had a quick spread in France since its legalization in 2001 and the income of a new hysteroscopic method. As a matter of fact, France is the second greater country for women having Essure® and the first country where Essure® method forestall surgical tubal ligation. Thus we focus on good practice and update knowledge about Essure® method. PMID:22658908

Panel, P; Jost, S; Grosdemouge, I; Friederich, L; Niro, J; Le Tohic, A

2012-05-31

310

Process Conditions and Microstructures of Ceramic Coatings by Gas Phase Deposition Based on Plasma Spraying  

NASA Astrophysics Data System (ADS)

Plasma spraying at very low pressure (50-200 Pa) is significantly different from atmospheric plasma conditions (APS). By applying powder feedstock, it is possible to fragment the particles into very small clusters or even to evaporate the material. As a consequence, the deposition mechanisms and the resulting coating microstructures could be quite different compared to conventional APS liquid splat deposition. Thin and dense ceramic coatings as well as columnar-structured strain-tolerant coatings with low thermal conductivity can be achieved offering new possibilities for application in energy systems. To exploit the potential of such a gas phase deposition from plasma spray-based processes, the deposition mechanisms and their dependency on process conditions must be better understood. Thus, plasma conditions were investigated by optical emission spectroscopy. Coating experiments were performed, partially at extreme conditions. Based on the observed microstructures, a phenomenological model is developed to identify basic growth mechanisms.

Mauer, G.; Hospach, A.; Zotov, N.; Vaßen, R.

2013-03-01

311

Determination of 17 ?-Estradiol in Rabbit Plasma by Gas Chromatography with Flame Ionization Detection  

PubMed Central

This article describes gas chromatography-flame ionization detection method for determination of 17 ?-estradiol in rabbit plasma. 17 ?-estradiol and internal standard progesterone were extracted from plasma using liquid–liquid extraction method. Linearity was found between 0.25 and 20 ?g/ml (r2=0.994) for plasma samples. Intra-day and inter-day precision, expressed as the relative standard deviation were less than 5.5%, and accuracy (relative error) was less than 3.5%. The mean recovery of 17 ?-estradiol samples was 94.4%. The limits of detection and quantification of method for plasma samples were 0.10 ?g/ml and 0.15 ?g/ml, respectively. Also, clinically used other 10 drugs were investigated to check for potential interferences and the method was successfully applied to the determination of 17 ?-estradiol in New Zealand white rabbits.

Yilmaz, B; Kadioglu, Y.

2012-01-01

312

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

SciTech Connect

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.

Charles Mones

2006-12-01

313

Numerical analysis of shroud gas effects on air entrainment into thermal plasma jet in ambient atmosphere of normal pressure  

NASA Astrophysics Data System (ADS)

A numerical analysis of the influence of air entrainment into the plasma jet on the thermal plasma characteristics is performed to provide a design basis for nontransferred plasma torches operated in an ambient air of atmospheric pressure along with shroud gas injection. The assumption of steady-state, axisymmetric, local thermodynamic equilibrium, and optically thin plasma is adopted in a two-dimensional modeling of thermal plasma flow with an annular shroud gas shell. A control volume method and a modified semi-implicit pressure linked equations revised algorithm (known as SIMPLER) are used for solving the governing equations, i.e., the conservation equations of mass, momentum, and energy along with the equations describing the so-called K-? model for flow turbulent kinetic energy (K) and its dissipation rate (?), and the mass fraction equations for gas mixing. The two-dimensional distributions of temperature and flow velocity of the thermal plasma jet as well as the air mole fraction mixed with the plasma are found in an exterior jet expanding region outside the torch, and they are compared for the two cases with and without shroud gas injection. As a result of calculations, the flow rate of the injected shroud gas and the location of its injector turn out to be major parameters for controlling ambient air entrainment. The calculations also reveal that the annular injection of shroud gas surrounding the plasma jet reduces air entrainment into the plasma jet remarkably while it does not significantly affect the plasma temperature and velocity. The present numerical modeling suggests the optimum design and operating values of an argon shroud gas injector for minimizing air entrainment into the thermal plasma flame ejected from the nontransferred plasma torch operated at normal pressure in the ambient atmosphere.

Kang, Kyoung Doo; Hong, Sang Hee

1999-05-01

314

Removal of NOx from Flue Gas by Reburning with Plasma Activated Natural Gas: Review and Economics  

Microsoft Academic Search

By initiating chain reactions that consume NOx, CHi radicals play an important role in natural gas reburning. In conventional reburning, most of the methane is consumed in reactions with oxygen to form CO, and does not produce CHi- radicals as intermediate products, which limits NO reduction efficiency. Activating natural gas externally to the boiler may generate a mixture of CHi

F. E. BARTOSZEK; L. R. VÁSQUEZ; W. HE; J. S. CHANG

1998-01-01

315

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

NASA Astrophysics Data System (ADS)

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.

Rao, Z. H.; Liao, S. M.; Tsai, H. L.

2010-02-01

316

Calibration strategy for semi-quantitative direct gas analysis using inductively coupled plasma mass spectrometry  

NASA Astrophysics Data System (ADS)

A process is described by which an ICP-MS equipped with an Octopole Reaction System (ORS) is calibrated using liquid phase standards to facilitate direct analysis of gas phase samples. The instrument response to liquid phase standards is analyzed to produce empirical factors relating ion generation and transmission efficiencies to standard operating parameters. Empirical factors generated for liquid phase samples are then used to produce semi-quantitative analysis of both mixed liquid/gas samples and pure gas samples. The method developed is similar to the semi-quantitative analysis algorithms in the commercial software, which have here been expanded to include gas phase elements such as Xe and Kr. Equations for prediction of relative ionization efficiencies and isotopic transmission are developed for several combinations of plasma operating conditions, which allows adjustment of limited parameters between liquid and gas injection modes. In particular, the plasma temperature and electron density are calculated from comparison of experimental results to the predictions of the Saha equation. Comparisons between operating configurations are made to determine the robustness of the analysis to plasma conditions and instrument operating parameters. Using the methods described in this research, the elemental concentrations in a liquid standard containing 45 analytes and treated as an unknown sample were quantified accurately to ± 50% for most elements using 133Cs as a single internal reference. The method is used to predict liquid phase mercury within 12% of the actual concentration and gas phase mercury within 28% of the actual concentration. The results verify that the calibration method facilitates accurate semi-quantitative, gas phase analysis of metal species with sufficient sensitivity to quantify metal concentrations lower than 1 ppb for many metallic analytes.

Gerdes, Kirk; Carter, Kimberly E.

2011-09-01

317

Mechanisms of disruptions caused by noble gas injection into tokamak plasmas  

NASA Astrophysics Data System (ADS)

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.

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

318

Intense microwave pulse propagation through gas breakdown plasmas in a waveguide  

SciTech Connect

High-power microwave pulse-compression techniques are used to generate 2.856 GHz pulses which are propagated in a TE/sub 10/ mode through a gas filled section of waveguide, where the pulses interact with self-generated gas-breakdown plasmas. Pulse envelopes transmitted through the plasmas, with duration varying from 2 ns to greater than 1 ..mu..s, and peak powers of a few kW to nearly 100 MW, are measured as a function of incident pulse and gas pressure for air, nitrogen, and helium. In addition, the spatial and temporal development of the optical radiation emitted by the breakdown plasmas are measured. For transmitted pulse durations greater than or equal to 100 ns, good agreement is found with both theory and existing measurements. For transmitted pulse duration as short as 2 ns (less than 10 rf cycles), a two-dimensional model is used in which the electrons in the plasma are treated as a fluid whose interactions with the microwave pulse are governed by a self-consistent set of fluid equations and Maxwell's equations for the electromagnetic field. The predictions of this model for air are compared with the experimental results over a pressure range of 0.8 torr to 300 torr. Good agreement is obtained above about 1 torr pressure, demonstrating that microwave pulse propagation above the breakdown threshold can be accurately modeled on this time scale. 63 refs., 44 figs., 2 tabs.

Byrne, D.P.

1986-10-08

319

Investigation of the gas flow effect on an atmospheric pressure RF plasma torch  

NASA Astrophysics Data System (ADS)

A cool atmospheric pressure non-thermal capactively-coupled RF discharge is studied. It is created between two parallel electrodes - a powered one supplied by 13.56 MHz, and a grounded one. The feed gas argon flows via holes between the electrodes where it is ionized. The plasma torch is studied by means of a time dependent two-dimensional fluid model. A simplified kinetic scheme with four active species is considered, namely argon excited atoms (Ar*), atomic (Ar+) ions, molecular (Ar2+) ions and electrons (e). The plasma dynamics in the space between the electrodes as well as in the extended region behind the grounded electrode is studied. The effect of the gas flow on the plasma is examined. Constriction of the plasma is induced by the field sustaining the discharge due to the sieve-like structure of the electrodes. As a result of the stationary gas flow the filaments extend beyond the electrodes ensuring a flow of active species in the afterglow.

Atanasova, M.; Mihailova, D.; Carbone, E.; van Dijk, J.; van der Mullen, J. J. A. M.; Benova, E.; Degrez, G.

2011-01-01

320

Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

Electron energy spectra of Xe atoms at He filled micro-plasma afterglow gas analyzer were observed using Collisional Electron Spectroscopy (CES) method [1]. According to CES, diffusion path confinement for characteristic electrons makes it possible to measure electrons energy distribution function (EEDF) at a high (up to atmospheric) gas pressure. Simple geometry micro-plasma CES sensor consists of two plane parallel electrodes detector and microprocessor-based acquisition system providing current-voltage curve measurement in the afterglow of the plasma discharge. Electron energy spectra are deduced as 2-nd derivative of the measured current-voltage curve to select characteristic peaks of the species to be detected. Said derivatives were obtained by the smoothing-differentiating procedure using spline least-squares approximation of a current-voltage curve. Experimental results on CES electron energy spectra at 10-40 Torr in pure He and in admixture with 0.3% Xe are discussed. It demonstrates a prototype of the new miniature micro-plasma sensors for industry, safety and healthcare applications. [1]. A.A.Kudryavtsev, A.B.Tsyganov. US Patent 7,309,992. Gas analysis method and ionization detector for carrying out said method, issued December 18, 2007.

Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

2012-10-01

321

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

SciTech Connect

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{sup 9} cm{sup -3} at an operating gas pressure in the vacuum chamber of less than 2x10{sup -2} Pa. The device features high power efficiency, design simplicity, and compactness.

Vizir, A. V.; Tyunkov, A. V.; Shandrikov, M. V.; Oks, E. M. [Institute of High Current Electronics, Russian Academy of Sciences, Tomsk 634055 (Russian Federation)

2010-02-15

322

The Role of a Photoresist Film on Reverse Gas Plasma Etching of Chromium Films  

NASA Astrophysics Data System (ADS)

The role of a photoresist film on reverse gas plasma etching of chromium photomask plates has been studied. The variation of etching profiles has been observed using SEM techniques. It is speculated that a WO3 layer on the chromium film forms a masking layer to the etching and that the WO3 layer can be removed by decomposition of the photoresist film in the plasma. A study of the relation between photoresist thickness and etching time has shown that there is an optimum photoresist thickness for each WO3 concentration in the chromium film.

Yamazaki, Teruhiko; Suzuki, Yoshiki; Uno, Jun; Nakata, Hidefumi

1980-07-01

323

Gas-discharge plasma initiated in air by a radiation pulse  

SciTech Connect

The authors consider the formation of a non-equilibrium gas-discharge plasma in air under the action of a radiation at a wavelength of 10.6 micrometers with a duration of 10/sup -6/ seconds. They show that the air discharge occurs under nonequilibrium conditions by formation of an autoionization complex with subsequent oscillatory excitation of molecules. They use the diffusion approximation to find the molecular distribution function over oscillatory degrees of freedom. They calculate the electron temperature and concentration in the breakdown plasma with consideration of multistep ionization of molecules and dissociative recombination of charged particles. In conclusion, they find that experimental results agree with their calculations.

Butakyi, V.I.; Tel'nikin, A.A.

1985-08-01

324

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

SciTech Connect

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)

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

325

Destruction and removal of toluene and MEK from gas streams with silent discharge plasmas  

SciTech Connect

The effectiveness of applying silent discharge plasmas (SDP) for destroying and removing volatile organic compounds (VOCs) from gas streams is experimentally evaluated with a laboratory-scale reactor. The VOCs selected for study include toluene and methyl ethyl ketone (MEK). Direct collision with energetic electrons and reaction with generated gas-phase radicals are two major mechanisms responsible for destruction and removal of VOCs from gas streams. Operating parameters investigated include applied voltage, gas residence time, and temperature and composition of the gas stream. Experimental results indicate that the removal efficiency of toluene and MEK achieved with SDP can be enhanced by operating the system at a higher gas temperature and applied voltage due to the generation of more energetic electrons and radicals. O{sub 2} is essential for removing VOCs from gas streams with SDP. More than 80% removal efficiencies were achieved with this system for both toluene and MEK. SDP can potentially serve as an alternative control technology for removing VOCs from gas streams.

Chang, M.B.; Chang, C.C. [National Central Univ., Chungli (Taiwan, Province of China). Graduate Inst. of Environmental Engineering

1997-05-01

326

RF Gas Plasma Source Development for Heavy Ion Fusion  

SciTech Connect

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.

Ahle, L; Hall, R P; Molvik, A W; Kwan, J W; Leung, K N

2001-09-04

327

RF gas plasma source development for heavy ion fusion  

SciTech Connect

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.

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

2002-02-22

328

Stopping power of a buffer gas for laser plasma debris mitigation  

SciTech Connect

The stopping power of a buffer gas against laser-plasma debris is quantitatively assessed by means of visualization techniques. For ablation of planar tin targets in an Ar ambient, an expanding wavefront was visualized, whose translation energy was rapidly reduced within a few millimeters above the target surface. The fastest debris component was along the normal to the target with an initial kinetic energy of 1.1 keV. The buffer gas efficiency changed in a line-of-sight-dependent way, thermalizing more efficiently the on-axis components. The maximum stopping power of the gas buffer was determined as high as 0.4 keV/mm. Due to the reduction in stopping power, nonlinearly with the debris kinetic energy, a gas buffer thickness of 10 mm is required at the studied atmospheric pressure in order to mitigate high energy debris below a fiducial threshold of 0.1 keV.

Bleiner, Davide [ETH Zurich, Sonneggstrasse 3, 8092 Zurich (Switzerland); Lippert, Thomas [Paul Scherrer Institute, 5232 Villingen-PSI (Switzerland)

2009-12-15

329

Sterilization in the United States  

PubMed Central

Unintended pregnancies are expensive for patients and for society in terms of medical costs, the cost of caring for more children, and the cost to personal and professional goals. Sterilization is the most common contraceptive method utilized by couples in the United States. Given technological advances over the past few decades, male and female surgical sterilization has become a safe, convenient, easy, and highly effective birth control method for the long term. This article reviews current male and female sterilization options.

Bartz, Deborah; Greenberg, James A

2008-01-01

330

Women, men, and contraceptive sterilization  

Microsoft Academic Search

Objective: To review the social and behavior contexts of decisions about contraceptive sterilization and to analyze factors associated with sterilization choices.Design: Multinomial logit regression of sterilization.Patient(s): Various subsamples as appropriate to specific analyses drawn from the 10,847 women interviewed in the 1995 National Survey of Family Growth, and the 5,227 men interviewed in the National Survey of Families and Households.Intervention(s):

Larry L Bumpass; Elizabeth Thomson; Amy L Godecker

2000-01-01

331

Comparison between gas puffing and supersonic molecular beam injection in plasma density feedback experiments in EAST  

NASA Astrophysics Data System (ADS)

To achieve desirable plasma density control, a supersonic molecular beam injection (SMBI) feedback control system has been developed recently for the EAST tokamak. The performance of the SMBI and gas puffing (GP) feedback systems were used and compared. The performance of pulse width mode is better than that of pulse amplitude mode when GP was used for density feedback control. During one-day experiments, the variation of gas input and wall retention can be clarified into two stages. In the first stage the retention ratio is as high as 80–90%, and the gas input is about an order of 1022 D2. However, in the second stage, the retention ratio is at a range of 50–70%. The gas input of a single discharge is small and the net wall retention grows slowly. The results of the SMBI feedback control experiment was analyzed. The shorter delay time of SMBI makes it faster at feeding back control the plasma density. The result showed that, compared with GP, the gas input of SMBI was decreased ?30% and the wall retention was reduced ?40%. This shows SMBI's advantage for the long pulse high density discharges in EAST.

Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Li, Jiahong; Ding, Rui; Cao, Bin; Wu, Jinhua

2013-11-01

332

Isothermal Expansion of a Solid-Particle-Entrained Gas and Plasma-Based Energy Conversion  

NASA Astrophysics Data System (ADS)

Experimental and theoretical research is reported on the expansion of a two-phase fluid consisting of a mixture of compressed gas and solid particles. Experimental temperature measurements indicate that the expansion is describable as isothermal for the conditions studied. During the expansion, the energy of the compressed gas is converted into kinetic energy of the solid particles. The solid particles travel at a subsonic speed, serve as a heat exchange medium, and are recycled. In the experiment, the gas-solid two-phase fluid travels through a nozzle during the isothermal expansion. Conversion of the energy of a compressed gas has been demonstrated experimentally using a turbine to convert the kinetic energy of the solid particles into other forms. A second method is also being studied for converting the kinetic energy of the solid particles after the gas expansion. The second method, which would replace the turbine, would convert the kinetic energy of the solid particles into electrical energy by charging the solid particles (e.g., by passing them through an electron plasma or by reflection off one plate of a capacitor). The charged solid particles would then carry a current across a change in electric potential inertially (without collisions with a wall) and then be discharged (e.g., by passing them through an ion plasma or by reflection off one plate of a second capacitor).

Lessmann, Eric; Traum, Matthew; Weathers, Duncan; Ordonez, Carlos

2011-03-01

333

Development and characterization of very dense submillimetric gas jets for laser-plasma interaction  

NASA Astrophysics Data System (ADS)

We report on the characterization of recently developed submillimetric He gas jets with peak density higher than 1021 atoms/cm3 from cylindrical and slightly conical nozzles of throat diameter of less than 400 ?m. Helium gas at pressure 300-400 bar has been developed for this purpose to compensate the nozzle throat diameter reduction that affects the output mass flow rate. The fast-switching electro-valve enables to operate the jet safely for multi-stage vacuum pump assembly. Such gaseous thin targets are particularly suitable for laser-plasma interaction studies in the unexplored near-critical regime.

Sylla, F.; Veltcheva, M.; Kahaly, S.; Flacco, A.; Malka, V.

2012-03-01

334

Development and characterization of very dense submillimetric gas jets for laser-plasma interaction  

SciTech Connect

We report on the characterization of recently developed submillimetric He gas jets with peak density higher than 10{sup 21} atoms/cm{sup 3} from cylindrical and slightly conical nozzles of throat diameter of less than 400 {mu}m. Helium gas at pressure 300-400 bar has been developed for this purpose to compensate the nozzle throat diameter reduction that affects the output mass flow rate. The fast-switching electro-valve enables to operate the jet safely for multi-stage vacuum pump assembly. Such gaseous thin targets are particularly suitable for laser-plasma interaction studies in the unexplored near-critical regime.

Sylla, F.; Kahaly, S.; Flacco, A.; Malka, V. [Laboratoire d'Optique Appliquee, ENSTA-ParisTech, CNRS, Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France); Veltcheva, M. [Laboratoire d'Optique Appliquee, ENSTA-ParisTech, CNRS, Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France); Dipartimento di Fisica ''G. Occhialini'', Universita degli Studi di Milano-Biccoca, piazza della Scienza 3, 20126 Milan (Italy)

2012-03-15

335

Development and characterization of very dense submillimetric gas jets for laser-plasma interaction.  

PubMed

We report on the characterization of recently developed submillimetric He gas jets with peak density higher than 10(21) atoms/cm(3) from cylindrical and slightly conical nozzles of throat diameter of less than 400 ?m. Helium gas at pressure 300-400 bar has been developed for this purpose to compensate the nozzle throat diameter reduction that affects the output mass flow rate. The fast-switching electro-valve enables to operate the jet safely for multi-stage vacuum pump assembly. Such gaseous thin targets are particularly suitable for laser-plasma interaction studies in the unexplored near-critical regime. PMID:22462922

Sylla, F; Veltcheva, M; Kahaly, S; Flacco, A; Malka, V

2012-03-01

336

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

NASA Astrophysics Data System (ADS)

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 understanding the dynamics of non-thermal plasmas in flame environments. In this concept, cold (in a generalized sense) barriers of gas play the role of the dielectrics, with some major differences in behaviour with respect to solid barriers. We present an analytical evaluation of the discharge appearance modes, new experimental results using helium-nitrogen layers that confirm the possibility of avoiding breakdown in the cold layers and a numerical evaluation that helps interpret the development of streamers once they reach a non-ionizing region.

Guerra-Garcia, C.; Martinez-Sanchez, M.

2013-08-01

337

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

338

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

PubMed

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

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

2010-12-28

339

Fast Plasma Shutdowns By Massive Hydrogen, Noble and Mixed-Gas Injection in DIII-D  

NASA Astrophysics Data System (ADS)

Experiments conducted with hydrogenic, noble and mixed (H2 + Ar and D2 + Ne) gases injected into H-mode plasmas are described. Gas species, quantity, delivery rate and intrinsic and added impurities (mixtures) all affect the disruption mitigation attributes of the resulting fast plasma shutdowns. With sufficient quantity, effective mitigation is obtained for all species. Optimal results for disruption and runaway avalanche mitigation are with 3x10^22 He delivery in ˜2 ms. This yields a favorable combination of moderately-fast current quench, high free-electron densities, ˜2x10^21,m-3, gas assimilation fractions ˜0.3 and avalanche suppression ratios, ne/nRB˜0.1. Favorable scaling of assimilation with increasing quantity is seen for all low-Z gases. The experiments provide validation data for emerging MHD/radiation simulation models and insight about design of injection systems for disruption and avalanche mitigation in ITER.

Wesley, J. C.; van Zeeland, M. A.; Evans, T. E.; Humphreys, D. A.; Hyatt, A. W.; Parks, P. B.; Strait, E. J.; Wu, W.; Hollmann, E. M.; Boedo, J. A.; Izzo, V. A.; James, A. N.; Moyer, R. A.; Rudakov, D. L.; Yu, J. H.; Jernigan, T. C.; Baylor, L. R.; Combs, S. K.; Groth, M.

2008-11-01

340

Electron Beam Transport in Gas and Plasma-filled Cells for Radiography  

NASA Astrophysics Data System (ADS)

In flash x-ray radiography, the paraxial diode utilizes a gas-filled transport cell to focus an electron beam into a small spot. In simulations, it has been shown that the primary limitation to achieving a small spot is due to time-dependent net currents in the transport cell which cause the beam's focal position to shift axially. This leads to a larger time-integrated spot than is desired. Further simulations suggest that replacing the gas with a preionized plasma significantly slows down the net current growth in the transport cell, thereby achieving a smaller spot. Recent experiments have been performed on the RITS-3 accelerator (4.5 MV, 70 ns). The basic physics principle of stabilizing the beam spot by incorporating a preionized plasma in the transport cell was demonstrated.

Hahn, Kelly; Welch, Dale; Schamiloglu, Edl; Portillo, Sal; Johnston, Mark; Oliver, Bryan; Maenchen, John

2006-10-01

341

Sterilization in Finland: From eugenics to contraception  

Microsoft Academic Search

The purpose of this paper was to describe the transition of sterilization in Finland from an eugenic tool to a contraceptive. Historical data were drawn from earlier reports in Finnish. Numbers of and reasons for sterilizations since 1950 were collected from nationwide sterilization statistics. Prevalence, characteristics of sterilized women, and women's satisfaction with sterilizations were studied from a 1994 nationwide

Elina Hemminki; Anja Rasimus; Erja Forssas

1997-01-01

342

Bacillus subtilis devitalization mechanism of atmosphere pressure plasma jet  

Microsoft Academic Search

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

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

2010-01-01

343

Thermal behavior of bovine serum albumin after exposure to barrier discharge helium plasma jet  

NASA Astrophysics Data System (ADS)

Non-thermal plasma jets at atmospheric pressure are useful tools nowadays in plasma medicine. Various applications are tested such as cauterization, coagulation, wound healing, natural and artificial surfaces decontamination, and sterilization. In order to know more about the effects of gas plasma on biological supramolecules, we exposed protein powders to a barrier discharge helium plasma jet. Then, spectroscopic investigations were carried out in order to obtain information on protein secondary, tertiary, and quaternary structures. We obtained a reduction of the protein alpha-helix content after the plasma exposure and a different behavior, for both thermal denaturation/renaturation kinetics and thermal aggregation process.

Jijie, R.; Pohoata, V.; Topala, I.

2012-10-01

344

Effect of Zr on microstructure of metallic glass coatings prepared by gas tunnel type plasma spraying.  

PubMed

Metallic glass is one of the most attractive advanced materials, and many researchers have conducted various developmental research works. Metallic glass is expected to be used as a functional material because of its excellent physical and chemical functions such as high strength and high corrosion resistance. However, the application for small size parts has been carried out only in some industrial fields. In order to widen the industrial application fields, a composite material is preferred for the cost performance. In the coating processes of metallic glass with the conventional deposition techniques, there is a difficulty to form thick coatings due to their low deposition rate. Thermal spraying method is one of the potential candidates to produce metallic glass composites. Metallic glass coatings can be applied to the longer parts and therefore the application field can be widened. The gas tunnel plasma spraying is one of the most important technologies for high quality ceramic coating and synthesizing functional materials. As the gas tunnel type plasma jet is superior to the properties of other conventional type plasma jets, this plasma has great possibilities for various applications in thermal processing. In this study, the gas tunnel type plasma spraying was used to form the metallic glass coatings on the stainless-steel substrate. The microstructure and surface morphology of the metallic glass coatings were examined using Fe-based metallic glass powder and Zr-based metallic glass powder as coating material. For the mechanical properties the Vickers hardness was measured on the cross section of both the coatings and the difference between the powders was compared. PMID:22905546

Kobayashi, A; Kuroda, T; Kimura, H; Inoue, A

2012-06-01

345

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

SciTech Connect

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.

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

346

Fatigue behaviour of T welded joints rehabilitated by tungsten inert gas and plasma dressing  

Microsoft Academic Search

This paper concerns a fatigue study on the effect of tungsten inert gas (TIG) and plasma dressing in non-load-carrying fillet welds of structural steel with medium strength. The fatigue tests were performed in three point bending at the main plate under constant amplitude loading, with a stress ratio of R=0.05 and a frequency of 7Hz.Fatigue results are presented in the

Armando L. Ramalho; José A. M. Ferreira; Carlos A. G. M. Branco

2011-01-01

347

Adhesion strength of plasma-sprayed hydroxyapatite coatings on laser gas-nitrided pure titanium  

Microsoft Academic Search

A layer of bioceramic HA was coated on laser gas-nitrided pure titanium and grit-blasted pure titanium substrates using plasma-spraying technique, respectively. X-ray diffraction analysis showed that the microstructures of the coating were mainly composed of HA, amorphous calcium phosphate (ACP) and some minute phases of tricalcium phosphate (TCP, ?-TCP and ?-TCP), tetracalcium phosphate (TTCP) and calcium oxide (CaO). The experimental

Sen Yang; H. C. Man; Wen Xing; Xuebin Zheng

2009-01-01

348

Characteristics of x-rays from a plasma focus operated with neon gas  

Microsoft Academic Search

The x-ray emission from a low-energy (2.3 kJ) plasma focus is investigated with neon as the filling gas. Two anode configurations are used in the experiment: the conventional cylindrical anode, and tapered anode slightly toward the open end. The latter geometry enhances soft x-ray emission by an order of magnitude. The emission is pressure dependent and, in both cases, the

M. Zakaullah; K. Alamgir; M. Shafiq; S. M. Hassan; M. Sharif; S. Hussain; A. Waheed

2002-01-01

349

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

Microsoft Academic Search

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

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

2001-01-01

350

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

Microsoft Academic Search

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

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

2008-01-01

351

Electrical and spectroscopic characterization of underwater plasma discharge inside rising gas bubbles  

Microsoft Academic Search

The generation of high-energetic species in plasma by discharge in liquids makes it suitable for applications such as water treatment. Effective reduction of input power and an increase in the process efficiency can be achieved by externally generated gas bubbles introduced in the liquid. Pulsed discharge in nitrogen, helium and argon bubbles in between a pin-to-plate electrode system submerged in

Patrick Vanraes; Anton Nikiforov; Christophe Leys

2012-01-01

352

Quantitative analysis of plasma acylcarnitines using gas chromatography chemical ionization mass f rag mentog rap hy  

Microsoft Academic Search

A stable isotope dilution gas chromatography chemical ionization mass spectrometry (GC-CI-MS) method was developed for the quantitative profiling of plasma acylcar- nitines. The clean-up procedure was comprised of a solid- phase cation exchange extraction using PRScolumns from which the acylcarnitines were eluted with a barium chloride solution. Isolated acylcarnitines were transformed into acylox- ylactones and analyzed by positive GC-CI-MS using

C. G. Costa; E. A. Stnays; A. Bootsma; H. J. ten Brink; L. Dorland; I. Tavares de Almeida; M. Duran; C. Jakobs

353

Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography–mass spectrometry  

Microsoft Academic Search

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 750ng\\/ml, and 750 to 3000ng\\/ml AJA. The intra- and inter-day precision (R.S.D., %), assessed across the linear

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

2005-01-01

354

Improved gas chromatographic–mass spectrometric method for the quantitative determination of vinpocetine in human plasma  

Microsoft Academic Search

An improved and validated method for the determination of vinpocetine in human plasma using a combination of a solid-phase extraction as a cleaning step followed by gas chromatography–mass spectrometry (GC–MS) has been presented. Quantitation has been carried out with apovincaminic acid methyl ester as internal standard. A limit of detection of 0.01 ng\\/ml, limit of quantitation of 0.10 ng\\/ml, as

M Vatsova; S Tzvetanov; A Drenska; J Goranscheva; N Tyutyulkova

1997-01-01

355

Measurements of large scale-length plasmas produced from gas-filled targets  

SciTech Connect

Apart from their intrinsic interest, plasma physics processes are important because they affect the coupling of the laser energy into laser-irradiated targets. Recently, new gas-filled targets have been developed to create large mm-size plasmas for the study of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). We present x-ray images and x-ray spectra to characterize these targets, which show that the plasmas are homogeneous, have electron densities of {approximately}10{sup 21} cm{sup {minus}3}, and attain electron temperatures of {approximately}3 keV. We also present SBS measurements to demonstrate how systematic studies of physical phenomena can be performed using these targets.

Back, C.A.; Berger, R.L.; Estabrook, K. [and others

1995-06-30

356

Effects of gas atmospheres on poly(lactic acid) film in acrylic acid plasma treatment  

NASA Astrophysics Data System (ADS)

Plasma polymerized acrylic acid (AA) coatings were deposited on poly(lactic acid) (PLA) films in various gas atmospheres during the pre-treatment of PLA and the deposition of AA, respectively. Therefore, this work was twofold: the argon pretreated PLA films followed by a deposition in argon were investigated against the mixture of argon and oxygen pretreated ones under the same deposition conditions; the plasma deposition of AA operating in different atmospheres (argon, oxygen and nitrogen) was employed to modify the pretreated PLA in oxygen. Chemical and physical changes on the plasma-treated surfaces were examined using contact angle, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and attenuated total reflection infrared (ATR-FTIR) analysis. The results showed that the discharge gas can have a significant influence on the chemical composition of the PLA surfaces: oxygen plasmas introduced oxygen-containing groups in company with surface etching in pretreatment and deposition, while argon discharges was able to achieve much better hydrophilic behavior and high retention ratio of poly(acrylic acid) (PAA) coating before and after washing in water.

Zhao, Yun; Fina, Alberto; Venturello, Alberto; Geobaldo, Francesco

2013-10-01

357

Laser-induced gas plasma etching of fused silica under ambient conditions  

NASA Astrophysics Data System (ADS)

Laser machining of optics to mitigate surface defects has greatly enhanced the ability to process large optics such as those found in fusion-class lasers. Recently, the use of assist reactive gases has shown promise in enhancing manifold etching rates relative to ambient conditions for CW-laser exposures. However, these methods still require significant heating of the substrate that induce residual stress, redeposit coverage, material flow, and compromise the final surface finish and damage threshold. While very reactive fluorinated gases are capable to reduce treatment temperatures even further, they are also inherently toxic and not readily transferable to large processing facilities. In this report, we look at whether a short-lived gas plasma could provide the safe and effective etchant sought, while still reducing the thermal load on the surface. We test this approach using a YAG laserinduced gas plasma to act as a source of the etchant for fused silica, a common optical material. The configuration and orientation of the beam and optical apparatus with respect to the surface was critical in preventing surface damage while etching the surface. Results with N2 and air gas plasmas are shown, along with a description of the various experimental implementations attempted.

Elhadj, Selim; Guss, Gabe; Matthews, Manyalibo J.; Bass, Isaac

2012-11-01

358

Precise and high-speed control of partial pressures of multiple gas species in plasma process chamber using pulse-controlled gas injection  

SciTech Connect

Multiprocesses in a single plasma process chamber with high throughput require precise, sequential, high-speed alteration of partial pressures of multiple gas species. A conventional gas-distribution system cannot realize this because the system seriously overshoots gas pressure immediately following valve operation. Furthermore, chamber volume and conductance of gas piping between the system and chamber should both be considered because they delay the stabilizing time of gas pressure. Therefore, the authors proposed a new gas-distribution system without overshoot by controlling gas flow rate based on pressure measurement, as well as a method of pulse-controlled gas injection immediately following valve operation. Time variation of measured partial pressure agrees well with a calculation based on an equivalent-circuit model that represents the chamber and gas piping between the system and chamber. Using pulse-controlled gas injection, the stabilizing time can be reduced drastically to 0.6 s for HBr added to pure Ar plasma, and 0.7 s for O{sub 2} added to Ar/HBr plasma; without the pulse control, the stabilizing times are 3 and 7 s, respectively. In the O{sub 2} addition case, rapid stabilization can be achieved during the period of line/space pattern etching of poly-Si on a thin SiO{sub 2} film. This occurs without anomalous etching of the underlying SiO{sub 2} film or the Si substrate near the sidewall, thus obtaining a wide process margin with high throughput.

Morishita, Sadaharu; Goto, Tetsuya; Nagase, Masaaki; Ohmi, Tadahiro [EES Technology Department of Technology, Development Center HQ, Industrial Automation Co., OMRON Corporation, Tokyo 141-0032 (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan); Osaka High-Tech Research and Development Center, Fujikin Incorporated, Osaka 559-0031 (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan)

2009-05-15

359

Comparison of Plasma Bilirubin Turnover in Man with Carbon Monoxide Production Estimated Simultaneously by Blood and Gas Measurements.  

National Technical Information Service (NTIS)

Carbon monoxide production in man was measured by both gas phase and by blood analysis. Both measurements correlated well with the simultaneous measurement of plasma bilirubin turnover, but the blood phase measurement is preferred since it is subject to l...

F. L. Rodkey P. D. Berk

1977-01-01

360

Remote Energetic Neutral Atom (ENA) Imaging of Space Plasma and Neurtal Gas in Harsh Radiation Environments: Applications to Jupiter  

NASA Astrophysics Data System (ADS)

We discuss requirements and general solutions to remotely image space plasma and neutral gas in the presence of harsh background radiation using Energetic Neutral Atoms (ENA). Focusing on applications for ESA JUpiter ICy moon Explorer (JUICE) mission.

Brandt, P. C.; Mitchell, D. G.; Westlake, J.; Mauk, B. H.; Mauk, C. P.; Krimigis, S. M.

2012-10-01

361

Effects of different disinfection and sterilization methods on tensile strength of materials used for single-use devices.  

PubMed

Driven by economic and time constraints, some medical centers and third parties are resterilizing single-use devices (SUDs) for reuse. The steam autoclave is quick, but most plastics used in SUDs cannot survive the temperature. Thus, a number of new methods of cleaning, disinfecting, and sterilizing these complex devices are being introduced on the market. The present study investigated the effects of a range of methods on the tensile strength of latex rubber, silicone elastomer, 2 different formulations of polyurethane, nylon, and high-density polyethylene (HDPE) specimens. The methods used were sodium hypochlorite bleach (Clorox), peracetic acid + hydrogen peroxide (Steris), formaldehyde gas (Chemiclave), low-temperature peracetic acid and gas plasma (Plazlyte), and low-temperature hydrogen peroxide gas plasma (Sterrad). The results showed that silicone elastomer was minimally affected, whereas the strengths of nylon, polyethylene, and latex were reduced by some of the methods. Depending on the formulation, the strength of polyurethane either increased or decreased. The data demonstrated that disinfection and sterilization can affect the tensile strength of certain materials used in medical devices. PMID:11831098

Brown, Stanley A; Merritt, Katharine; Woods, Terry O; McNamee, Scott G; Hitchins, Victoria M

362

Sterilization of Extracted Human Teeth.  

ERIC Educational Resources Information Center

|At present, there is no specific recommendation for sterilization of extracted human teeth used in dental technique courses. The purpose of this study was to determine whether autoclaving would be effective in the sterilization of extracted teeth without compromising the characteristics that make their use in clinical simulations desirable. (MLW)|

Pantera, Eugene A., Jr.; Schuster, George S.

1990-01-01

363

Sterilization of Extracted Human Teeth.  

ERIC Educational Resources Information Center

At present, there is no specific recommendation for sterilization of extracted human teeth used in dental technique courses. The purpose of this study was to determine whether autoclaving would be effective in the sterilization of extracted teeth without compromising the characteristics that make their use in clinical simulations desirable. (MLW)

Pantera, Eugene A., Jr.; Schuster, George S.

1990-01-01

364

A New Cold Sterilization Unit.  

National Technical Information Service (NTIS)

The reasons for an absolutely reliable cold sterilization method are outlined. Experience with a new sterilization unit operating with ethylene oxide under tension, operating at 5.5 atmospheres and 55 C is discussed. The device can also be used for packag...

M. Schmidt-mende W. Heiss

1976-01-01

365

21 CFR 880.6880 - Steam sterilizer.  

Code of Federal Regulations, 2013 CFR

...and Personal Use Miscellaneous Devices § 880.6880 Steam sterilizer. (a) Identification. A steam sterilizer (autoclave) is a device that is intended for use by a health care provider to sterilize medical products by means of pressurized...

2013-04-01

366

9 CFR 109.2 - Sterilizers.  

Code of Federal Regulations, 2013 CFR

...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 sterilizers used...

2013-01-01

367

Experiences with a New Cold Sterilization Unit.  

National Technical Information Service (NTIS)

The use of ethylene oxide for cold sterilization is discussed. The chemical and physical properties of this compound are first reviewed. Sterilization methods are then described along with applications of these methods to the sterilization of medical equi...

W. Heiss M. Schmidt-mende

1976-01-01

368

Influence of gas mixture ratio on the luminous efficiency in surface discharge alternating current plasma display panels  

Microsoft Academic Search

The improvement of luminosity and luminous efficiency is the one of the most important tasks in alternating current plasma display panels. The influence of gas mixture ratio, Ne–Xe and He–Ne(27%)–Xe(3%), on luminosity and luminous efficiency in surface discharge alternating-current plasma display panels has been investigated. It is found that discharge power does not strongly depend on the gas mixtures, while

J. C. Ahn; T. Y. Kim; J. J. Ko; Y. Seo; G. S. Cho; E. H. Choi

2000-01-01

369

Influence of gas mixture ratio on the luminous efficiency in surface discharge alternating current plasma display panels  

Microsoft Academic Search

The improvement of luminosity and luminous efficiency is the one of the most important tasks in alternating current plasma display panels. The influence of gas mixture ratio, Ne-Xe and He-Ne(27%)-Xe(3%), on luminosity and luminous efficiency in surface discharge alternating-current plasma display panels has been investigated. It is found that discharge power does not strongly depend on the gas mixtures, while

J. C. Ahn; T. Y. Kim; J. J. Ko; Y. Seo; G. S. Cho; E. H. Choi

2000-01-01

370

NO x removal from the flue gas of oil-fired boiler using a multistage plasma-catalyst hybrid system  

Microsoft Academic Search

The study on removal of NOx from the flue gas of oil-fired boiler has been carried out using non-thermal plasma cum catalyst hybrid reactor at 150 °C. Propylene (C3H6) was used as a reducing agent. A multistage plasma-catalyst hybrid reactor was newly designed and successfully operated to clean up the flue gas stream having a flow rate of 30 Nm3\\/h. TiO2 and

Sung Youl Park; Bal Raj Deshwal; Seung Hyun Moon

2008-01-01

371

Improving parallel scalability for edge plasma transport simulations with neutral gas species  

NASA Astrophysics Data System (ADS)

Simulating the transport of multi-species plasma and neutral species in the edge region of a tokamak magnetic fusion energy device is computationally intensive and difficult due to coupling among various components, strong nonlinearities and a broad range of temporal scales. In addition to providing boundary conditions for the core plasma, such models aid in the understanding and control of the associated plasma/material-wall interactions, a topic that is essential for the development of a viable fusion power plant. The governing partial differential equations are discretized to form a large nonlinear system that typically must be evolved in time to obtain steady-state solutions. Fully implicit techniques using preconditioned Jacobian-free Newton-Krylov methods with parallel domain-based preconditioners are shown to be robust and efficient for the plasma components. Inclusion of neutral gas components, however, increases the condition number of the system to the point where improved parallel preconditioning is needed. Standard algebraic preconditioners that provide sufficient coupling throughout the global domain to handle the neutrals are not generally scalable. We present a new preconditioner, termed FieldSplit, which exploits the character of the neutral equations to improve the scalability of the combined plasma/neutral system.

McCourt, M.; Rognlien, T. D.; McInnes, L. C.; Zhang, H.

2012-01-01

372

The effects of neutral gas pressure and electron temperature on the dynamics of the electron diffusion gauge experiment electron plasma  

Microsoft Academic Search

The dynamics of pure, electron plasmas confined in cylindrically symmetric, Malmberg-Penning traps are strongly affected by imperfections in the trap fields and collisions with background gas molecules present in the vacuum. These imperfections in the trap torque the azimuthally rotating plasma, causing it to expand radially. The Electron Diffusion Gauge (EDG) device is used to determine whether the effects of

Kyle Adam Morrison

2004-01-01

373

Influence of different layer microstructures induced by different gas compositions on corrosion behavior of plasma nitrided stainless steel  

Microsoft Academic Search

AISI 316 austenitic stainless steels have been plasma nitrided using a dc glow discharge unit in order to investigate the influence of gas composition on microstructure and corrosion behavior of treated samples. Corrosion properties of untreated and plasma nitrided 316 steels have been evaluated using anodic polarization tests in 1 N H2SO4 solution. Qualitative evaluation was carried out using surface analyses

Saeid Amiri; Masoud Moradshahi

2007-01-01

374

Gas-Phase Pollutant Decomposition with Non-Thermal Plasmas: Simple Removal Equations and Figures-of Merit.  

National Technical Information Service (NTIS)

Non-thermal plasmas (NTPs) are a type of advanced oxidation and reduction technology for treating gas-phase chemical pollutants. Such plasmas are good sources of highly reactive oxidative and reductive species (free radicals and others), e.g., O(P3), OH, ...

L. A. Rosocha

1999-01-01

375

Three-dimensional effects of carrier gas and particle injections on the thermo-fluid fields of plasma jets  

Microsoft Academic Search

A numerical model is developed to clarify three-dimensional effects of the radial injection of carrier gas and particles on the thermo-fluid fields of the plasma jet with and without swirl. The plasma-particle two-way interactions are modelled by coupling a Lagrangian approach for particle behaviour with an Eulerian approach for plasma flow under dense loading. The effect of radial injection of

Kandasamy Ramachandran; Hideya Nishiyama

2002-01-01

376

Combined plasma gas-phase synthesis and colloidal processing of InP\\/ZnS core\\/shell nanocrystals  

Microsoft Academic Search

Indium phosphide nanocrystals (InP NCs) with diameters ranging from 2 to 5 nm were synthesized with a scalable, flow-through, nonthermal plasma process at a rate ranging from 10 to 40 mg\\/h. The NC size is controlled through the plasma operating parameters, with the residence time of the gas in the plasma region strongly influencing the NC size. The NC size

Ryan Gresback; Ryan Hue; Wayne L Gladfelter; Uwe R Kortshagen

2011-01-01

377

Freezing and Melting of 3D Complex Plasma Structures under Microgravity Conditions Driven by Neutral Gas Pressure Manipulation  

SciTech Connect

Freezing and melting of large three-dimensional complex plasmas under microgravity conditions is investigated. The neutral gas pressure is used as a control parameter to trigger the phase changes: Complex plasma freezes (melts) by decreasing (increasing) the pressure. The evolution of complex plasma structural properties upon pressure variation is studied. Theoretical estimates allow us to identify the main factors responsible for the observed behavior.

Khrapak, S. A.; Klumov, B. A. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany); Joint Institute for High Temperatures, 125412 Moscow (Russian Federation); Huber, P.; Thomas, H. M.; Ivlev, A. V.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany); Molotkov, V. I.; Lipaev, A. M.; Naumkin, V. N.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, 125412 Moscow (Russian Federation); Malentschenko, Yu.; Volkov, S. [Yuri Gagarin Cosmonaut Training Centre, 141160 Star City (Russian Federation)

2011-05-20

378

[Sterility in medieval noblemen].  

PubMed

The social competence of the medieval nobleman was closely associated with his male sense of honour. One essential aspect of his masculinity was the ability to produce progeny. The childlessness of a good ruler needed special justification, the childlessness of a bad ruler was seen as God's punishment. In terms of canon law, the inability to procreate was irrelevant as long as the marriage could be consummated. Considering the importance of the procreative capacity and its symbolic significance one must ask to what extent it was possible to ascertain sterility in the Middle Ages. In the case of noblemen one can assume that they could obtain certainty about their fertility through their premarital and extramarital intercourse. This might explain why some rulers and nobles accepted a childless marriage without deeming it necessary to take another wife (or plan their itinerary in a way that enabled them to produce progeny). PMID:20506725

van Eickels, Klaus

2009-01-01

379

Female sterilization occlusion techniques.  

PubMed

There are several different female sterilization occlusion techniques. Tubes can be tied, blocked with mechanical devices such as clips or rings, or scarred closed with electric current. In partial salpingectomy, the most common occlusion technique, the fallopian tubes are cut and tied with a suture material. This approach is safe, effective, easy to learn, and does not require any special equipment. Titanium or plastic clips block the fallopian tubes by clamping down and cutting off the blood supply to a portion of the tubes, causing sufficient scarring or fibrosis to prevent fertilization. Silicone rings also are used to block the tubes mechanically. A small loop of tube is pulled through the stretched ring and the resultant scarring blocks passage of the sperm or egg. Finally, electrocoagulation uses electric current to coagulate a small portion of each fallopian tube. This technique is rarely used, however, because of the risk of organ injury. PMID:12321060

Keller, S

1997-01-01

380

Experimental Study of Plasma Cooling and Laser Beam Interaction in Gas Filled ICF Engines  

NASA Astrophysics Data System (ADS)

ICF power plants, such as the LIFE scheme under development at LLNL, may employ a high-Z, target-chamber gas-fill to moderate the first-wall heat-pulse due to x-rays and energetic ions released during target detonation. This gas-fill is heated and ionized by this energy release. It must cool and recombine before the next shot (at nominally 70-ms intervals) to a temperature where the next target and laser pulse can propagate to chamber center with minimal degradation. While we expect rapid cooling to 2eV by radiation, our modeling of cooling below 2 eV has a high degree of uncertainty. We have developed a plasma source to study the cooling rates and laser propagation in high-Z gaseous plasmas. The source is a theta discharge configuration driven by a low-inductance, 5-kJ, 100-ns pulsed power system. This configuration delivers high peak power levels, has an electrode-less discharge, and has unobstructed axial access for diagnostics and beam propagation studies. Our diagnostics include Thompson scattering, time resolved spectroscopy, and plasma probes. We will report on the system design, operation, and initial results.

Rhodes, Mark; Kane, Jave; Loosmore, Gwendolen; Demuth, James; Latkowski, Jeffery

2010-11-01

381

Effect of laser ablation plasma on dynamics of a laser absorption wave in a gas  

SciTech Connect

Experimental results indicate deceleration of the detonation wave under conditions of partial absorption of laser radiation when both plasmas--detonation wave and ablation plasma--are ignited simultaneously. The observed effect is attributed to a reduction of laser radiation intensity, reflected by the target surface and transmitted back to the detonation wave, due to the absorption in the dense ionized vapor of the target material. Also, we report results of studies on dynamics of axial and radial shock waves formed in a gas during propagation of the detonation wave. The observed differences between experimental results and self-similar computations are attributed to the effect of the hot gas transfer along the laser beam axis out of the zone of absorption of laser radiation. All the experiments were performed using carbon-dioxide laser with pulse width of a few microseconds and energy of 1 J. We employed streak camera, fast diodes, CCD camera imaging, and plasma transparency measurement techniques for data acquisition.

Anisimov, Vladimir N.; Grishina, Valeria G.; Derkach, Oleg N.; Malyta, Dmitry D.; Sebrant, Andrey Y. [Institute of Laser Physics, National Research Center-Kurchatov Institute, Kurchatov Square, Moscow, 123098 (Russian Federation)

1997-04-15

382

An enhanced plasma-catalytic method for DeNOx in simulated flue gas at room temperature.  

PubMed

A combined adsorption-discharge plasma process was proposed for DeNOx in simulated flue gas at room temperature. The conversion of NOx to N2 could achieve 95% in the process of NOx storage and reduction with NH3 under simulated flue gas conditions. PMID:24003442

Wang, Hui; Li, Xiangxiang; Chen, Ping; Chen, Min; Zheng, Xiaoming

2013-09-17

383

Pain Associated With Hysteroscopic Sterilization  

PubMed Central

Background and Objectives: The safety and efficacy of female hysteroscopic sterilization using the Essure system has been well documented. Given the marked differences in the execution of hysteroscopic and laparoscopic sterilization, the objective of this study was to assess the experience of pain postprocedure between the 2. Secondary end-points included postoperative pain medication, time to return to normal activities, postprocedure bleeding, and patient satisfaction. Methods: Twenty cases each of laparoscopic sterilization (LS) and hysteroscopic sterilization (HS) were performed. Patients were surveyed regarding their experience of pain immediately postoperatively, 1 week, and 4 weeks post-procedure. Results: The average pain score immediately postprocedure was significantly lower among HS patients than among LS patients (t=?8.17, P<.0001). One-week post-procedure, none of the patients in the HS group reported any pain, while the average pain score among the LS patients was 2.65 (t =?9.67, P<.0001). Four weeks post-procedure, women in the HS group continued to report no pain, 35% of the LS group continued to report some pain (t=?3.04, P=.004). Conclusions: Hysteroscopic sterilization offers a minimally invasive, less painful, equally efficacious modality for sterilization than laparoscopic sterilization and should be available to all women seeking permanent birth control.

Levy, Jenna; Childers, Meredith E.

2007-01-01

384

Comparison of European and US biological indicators for ethylene oxide sterilization  

Microsoft Academic Search

Summary Biological indicators (BIs) are used to monitor ethylene oxide (EO) gas sterilization processes for medical devices. Several European and United States BIs for EO sterilization were evaluated for resistance according to both United States Pharmacopeia (USP) XXI and United Kingdom's (UK) tests for D-values. US BIs areB. subtilis var. niger spores on paper strips or disc carriers while European

Christopher A. Demitrius; Anthony P. Duran; Virginia C. Chamberlain; Victoria M. Hitchins

1993-01-01

385

The interaction of energetic charged particles with gas and boundaries in the particle simulation of plasmas  

NASA Astrophysics Data System (ADS)

In many areas of plasma physics, the interaction of energetic particles with boundaries and background gas plays a key role in the dynamics. Examples include wakefield accelerators, high power microwave sources, and fusion devices. There are several key phenomena involved in these interactions such as collisions, radiation and photoemission. For this work, we adopt particle-in-cell plasma simulation codes by developing and adding models to existing 1D and 2D. This work comprises three parts: a relativistic collision model, a particle-fluid/particle-particle hybrid collision model, and radiation and photoemission generation by energetic particle interaction with solid surfaces. Previously, collision models were developed for the particle simulation of plasmas in the classical regime, however, the classical model breaks down as energies approach the relativistic regime. In this work, a relativistic Monte Carlo collision model is developed, adding relativistic collision dynamics and improved relativistic differential cross sections. With this model, we extend our simulation capabilities to predict and analyze the time-dependent performance of wakefield accelerators. In many practical collisional plasma models, such as in oxygen, nitrogen, or air, both target and projectile species in collisions may be particle species, reacting with many other particle and fluid species. A hybrid collision model is introduced to model the reactions between particle and fluid species as well as those between particle and particle species. A hybrid collision model enables particle-in-cell simulation of air or oxygen dielectric breakdown in high power microwave devices, as well as hydrocarbon collisions in the diverter sheath region in a tokamak magnetic fusion reactor. A computational model has been developed to describe xray generation for energetic particle impact with surfaces in the particle simulation of plasmas, and photoemission of electrons due to photon impact (e.g. xrays). Xray and photoemission may be one of the sources for generation of a first electron, leading to dielectric multipactor breakdown at the vacuum window in high power microwave devices. We are able to predict the energy and angular spectra of xrays generated by energetic impact of electrons on surfaces in high power microwave devices with the xray generation model. After building each model, we compared our simulation results with experiments and analytic solutions in order to verify our models and demonstrate the new modeling capabilities. The models developed in this work expand the regime of validity for particle simulation of collisional plasmas to higher energy, and enable study of interaction of energetic charged particles with surfaces, background gas, and reactive plasma constituents.

Lim, Chul-Hyun

386

Fast valve and nozzle for gas-puff operation of dense plasma focus  

SciTech Connect

A simple and reliable valve and nozzle system for a very fast injection of gas has been designed and constructed for its use in gas-puff mode of dense plasma focus experiments. It delivers a very quick rise time: 55 {mu}s. The pressure measured in our setup at a distance of 15 mm from the nozzle output is about 0.285 mbar, with a plenum pressure of 3 bars (absolute). The time between the valve aperture and pressure front arrival is 360 {mu}s. This result comes up as an average of about a hundred measurements. The energy input is 95 J (270 V on a 3000 {mu}F capacitor bank). The typical dimensions of the valve are 52 mm in diameter and 80 mm in length. The entire volume of the valve is, then, very small. The relative low pressure and voltage operation are significant advantages of this development. The performance of the valve satisfactorily fulfills the objectives of gas-puff plasma focus operation.

Milanese, Maria M.; Pouzo, Jorge O.; Cortazar, Osvaldo D.; Moroso, Roberto L. [Dense Plasma Group (GPDM), Instituto de Fisica Arroyo Seco, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, Tandil, Buenos Aires 7000 (Argentina) and CONICET, Avenida Rivadavia 1917, 1033 Buenos Aires (Argentina)

2006-03-15

387

Plasma structures observed in gas breakdown using a 1.5 MW, 110 GHz pulsed gyrotron  

SciTech Connect

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/cm{sup 2}. 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, SF{sub 6}, 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/cm{sup 2} was found to be of the order of 10 km/s.

Hidaka, Yoshiteru; Choi, E. M.; Mastovsky, I.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, 167 Albany St., Cambridge, Massachusetts 02139 (United States); Edmiston, G. F.; Neuber, A. A. [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering and Physics, Texas Tech University, MS 43102, Lubbock, Texas 79409 (United States); Oda, Y. [Naka Fusion Research Institute, Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0196 (Japan)

2009-05-15

388

Isolation and derivatization of plasma taurine for stable isotope analysis by gas chromatography-mass spectrometry  

SciTech Connect

A method for the isolation and derivatization of plasma taurine is described that allows stable isotope determinations of taurine to be made by gas chromatography-mass spectrometry. The isolation procedure can be applied to 0.1 ml of plasma; the recovery of plasma taurine was 70 to 80%. For gc separation, taurine was converted to its dimethylaminomethylene methyl ester derivative which could not be detected by hydrogen flame ionization, but could be monitored readily by NH/sub 3/ chemical ionization mass spectrometry. The derivatization reaction occurred partially on-column and required optimization of injection conditions. Using stable isotope ratiometry multiple ion detection, (M + 2 + H)/sup +//(M + H)/sup +/ ion ratio of natural abundance taurine was determined with a standard deviation of less than +-0.07% of the ratio. The (1,2-/sup 13/C)taurine/taurine mole ratios of standard mixtures could be accurately determined to 0.001. This stable isotope gc-ms method is suitable for studying the plasma kinetics of (1,2-/sup 13/C)taurine in infants who are at risk with respect to taurine depletion.

Irving, C.S.; Klein, P.D.

1980-09-01

389

Investigation into the determination of trimethylarsine in natural gas and its partitioning into gas and condensate phases using (cryotrapping)\\/gas chromatography coupled to inductively coupled plasma mass spectrometry and liquid\\/solid sorption techniques  

Microsoft Academic Search

Speciation of trialkylated arsenic compunds in natural gas, pressurized and stable condensate samples from the same gas well was performed using (Cryotrapping) Gas Chromatography-Inductively Coupled Plasma Mass Spectrometry. The major species in all phases investigated was found to be trimethylarsine with a highest concentration of 17.8 ng\\/L (As) in the gas phase and 33.2 ?g\\/L (As) in the stable condensate phase. The

E. M. Krupp; C. Johnson; C. Rechsteiner; M. Moir; D. Leong; J. Feldmann

2007-01-01

390

Quantitative analysis of trimethylsilyl derivative of hydroxyurea in plasma by gas chromatography-mass spectrometry.  

PubMed

Hydroxyurea is an antitumor drug widely used in the treatment of sickle cell disease. The drug has been analyzed in biological fluids by a number of high-performance liquid chromatography (HPLC) methods. This paper describes a fast and highly reliable capillary gas chromatography-mass spectrometry (GC-MS) procedure that was developed for the detection and quantitation of hydroxyurea in plasma. The compound and its labeled internal standard were liquid extracted from plasma and derivatized with BSTFA before analysis. The detection limit of the assay was 0.078 microg/ml and the limit of quantitation was 0.313 microg/ml with linearity up to 500 microg/ml. Intra-day variation, as coefficient of variation (C.V., %) over the selected concentration range, was 0.3-8.7% and inter-day variation was 0.4-9.6%. PMID:16378766

James, Hutchinson; Nahavandi, Masoud; Wyche, Melville Q; Taylor, Robert E

2005-12-27

391

Effects of helium gas mixing on the production of active species in nitrogen plasma  

NASA Astrophysics Data System (ADS)

Optical emission spectroscopy is used to investigate the effects of helium gas mixing on the electron temperature and the production of active species in nitrogen plasma generated by 50 Hz pulsed-DC power source. The electron temperature is determined from He I line intensities, using Boltzmann's plot method. The relative changes in the concentration of active species N2(C??u3) and N+2(B??u+2) are monitored by measuring the emission intensities of nitrogen (0 0) bands of the second positive and the first negative systems. It is found that the electron temperature can be raised considerably by mixing helium in nitrogen plasma, which in return plays a significant role in enhancing the concentration of active species through Penning effect of metastable states of the helium.

Naveed, M. A.; Qayyum, A.; Ali, Shujaat; Zakaullah, M.

2006-12-01

392

Surface Decontamination of Simulated Chemical Warfare Agents Using a Nonequilibrium Plasma with Off-Gas Monitoring  

SciTech Connect

InnovaTek is developing a surface decontamination technology that utilizes active species generated in a nonequilibrium corona plasma. The plasma technology was tested against DMMP, a simulant for the chemical agent Sarin. GC-MS analysis showed that a greater than four log10 destruction of the DMMP on an aluminum surface was achieved in a 10 minute treatment. An ion-trap mass spectrometer was utilized to collect time-resolved data on the treatment off-gases. These data indicate that only non-toxic fragments of the broken down DMMP molecule were present in the gas phase. The technology is being further refined to develop a product that will not only decontaminate surfaces but will also sense when decontamination is complete

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

2002-08-01

393

Diagnosis of gas temperature, electron temperature, and electron density in helium atmospheric pressure plasma jet  

SciTech Connect

The optical emission spectra of helium atmospheric pressure plasma jet (APPJ) are captured with a three grating spectrometer. The grating primary spectrum covers the whole wavelength range from 200 nm to 900 nm, with the overlapped grating secondary spectrum appearing from 500 nm to 900 nm, which has a higher resolution than that of the grating primary spectrum. So the grating secondary spectrum of OH (A{sup 2}{Sigma} {sup +}({upsilon} Prime = 0) {yields} X{sup 2}{Pi}({upsilon} Double-Prime = 0)) is employed to calculate the gas temperature (T{sub g}) of helium APPJ. Moreover, the electron temperature (T{sub e}) is deduced from the Maxwellian electron energy distribution combining with T{sub g}, and the electron density (n{sub e}) is extracted from the plasma absorbed power. The results are helpful for understanding the physical property of APPJs.

Chang Zhengshi; Zhang Guanjun; Shao Xianjun; Zhang Zenghui [State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

2012-07-15

394

EUV emission from gas discharges produced plasmas with solid tin as target  

NASA Astrophysics Data System (ADS)

Extreme ultraviolet (EUV) radiation with wavelengths of 11-14 nm is seen as the most promising candidate for a new lithographic technology. In the development of our Z-pinch plasma EUV source, xenon (Xe) is used for the background gas discharges and a solid tin (Sn) rod is used as target material due to its potential for high conversion efficiency (CE) from input electric energy to EUV radiation. The Z-pinch plasma was driven by pulsed current with amplitude of 30 kA and pulse duration of 110 ns. Pinhole imaging, an EUV spectrograph and an in-band EUV energy monitor were used to characterize the EUV emission from the Z-pinch discharge. Previously reported experimental analyses by Horita et al have demonstrated that the CE was as high as 3%.

Zhang, C. H.; Katsuki, S.; Imamura, H.; Horita, H.; Namihira, T.; Akiyama, H.

2005-12-01

395

Characterization of fuel gas products from the treatment of solid waste streams with a plasma arc torch.  

PubMed

This work addresses the plasma treatment of two solid waste streams and production of fuel gases from the process. In this study, carpet waste and simulated solid wastes generated by a United States Air Force Basic Expeditionary Airfield Resources Base deployment were used. Waste was treated in a furnace fitted with a 100kW plasma arc torch. The off gas was analyzed to determine its composition. The product gas was composed primarily of carbon monoxide and hydrogen, with small amounts of methane, benzene and toluene also detected. These experiments demonstrate the feasibility of producing fuel gases by plasma treatment of the solid waste streams. While the thermal energy value of the fuel gas produced in these experiments was less than the energy input, a higher waste-to-fuel gas conversion efficiency is expected in full-scale application. PMID:16563605

Vaidyanathan, Ambarish; Mulholland, James; Ryu, Jaeyong; Smith, Michael Stuart; Circeo, Louis J

2006-03-23

396

PLASMA GENERATOR  

DOEpatents

This patent describes apparatus for producing an electricity neutral ionized gas discharge, termed a plasma, substantially free from contamination with neutral gas particles. The plasma generator of the present invention comprises a plasma chamber wherein gas introduced into the chamber is ionized by a radiofrequency source. A magnetic field is used to focus the plasma in line with an exit. This magnetic field cooperates with a differential pressure created across the exit to draw a uniform and uncontaminated plasma from the plasma chamber.

Foster, J.S. Jr.

1958-03-11

397

Splash plasma channels produced by picosecond laser pulses in argon gas for laser wakefield acceleration  

NASA Astrophysics Data System (ADS)

Short-lived, ˜10ps, deep plasma channels, with their lengths of ˜1mm and diameters of ˜20?m, are observed and characterized in Ar gas jets irradiated by moderate intensity, ˜1015-16W/cm2, laser pulses with a duration from subpicosecond to several picoseconds. The channels, upon 2D particle-in-cell simulations including ionization, fit well in the guiding of high intensity femtosecond laser pulses and, therefore, in laser wakefield acceleration with a controllable electron self-injection.

Mizuta, Y.; Hosokai, T.; Masuda, S.; Zhidkov, A.; Makito, K.; Nakanii, N.; Kajino, S.; Nishida, A.; Kando, M.; Mori, M.; Kotaki, H.; Hayashi, Y.; Bulanov, S. V.; Kodama, R.

2012-12-01

398

Direct measurement of neutral gas heating in a radio-frequency electrothermal plasma micro-thruster  

NASA Astrophysics Data System (ADS)

Direct measurements and modelling of neutral gas heating in a radio-frequency (13.56 MHz) electrothermal collisional plasma micro-thruster have been performed using rovibrational band matching of the second positive system of molecular nitrogen (N2) for operating pressures of 4.5 Torr down to 0.5 Torr. The temperature measured with decreasing pressure for 10 W power input ranged from 395 K to 530 K in pure N2 and from 834 K to 1090 K in argon with 1% N2. A simple analytical model was developed which describes the difference in temperatures between the argon and nitrogen discharges.

Greig, A.; Charles, C.; Hawkins, R.; Boswell, R.

2013-08-01

399

Lattice location of deuterium in plasma and gas charged Mg doped GaN  

SciTech Connect

The authors have used ion channeling to examine the lattice configuration of deuterium in Mg doped GaN grown by MOCVD. The deuterium is introduced both by exposure to deuterium gas and to ECR plasmas. A density functional approach including lattice relaxation, was used to calculate total energies for various locations and charge states of hydrogen in the wurtzite Mg doped GaN lattice. Computer simulations of channeling yields were used to compare results of channeling measurements with calculated yields for various predicted deuterium lattice configurations.

Wampler, W.R.; Barbour, J.C.; Seager, C.H.; Myers, S.M. Jr.; Wright, A.F.; Han, J.

1999-12-02

400

Fabrication and testing of gas filled targets for large scale plasma experiments on Nova  

SciTech Connect

An experimental campaign on the Nova laser was started in July 1993 to study one st of target conditions for the point design of the National Ignition Facility (NIF). The targets were specified to investigate the current NIF target conditions--a plasma of {approximately}3 keV electron temperature and an electron density of {approximately}1.0 E + 21 cm{sup {minus}3}. A gas cell target design was chosen to confine as gas of {approximately}0.01 cm{sup 3} in volume at {approximately} 1 atmosphere. This paper will describe the major steps and processes necessary in the fabrication, testing and delivery of these targets for shots on the Nova Laser at LLNL.

Stone, G.F.; Spragge, M.; Wallace, R.J. [Lawrence Livermore National Lab., CA (United States); Rivers, C.J. [Lawrence Livermore National Lab., CA (United States)]|[Schafer (W.J.) Associates, Inc., Livermore, CA (United States)

1995-03-06

401

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

SciTech Connect

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.

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

402

Low density gas and foam targets for ICF long scale length plasma experiments: Fabrication and characterization  

NASA Astrophysics Data System (ADS)

Recent ICF experiments performed by the laser-matter interaction group at Los Alamos using the Nova laser to investigate long scale length plasmas required two types of special targets: gas-filled hohlraums and free-standing low density foams, both with densities in the range of 3-5 mg/cc. The mass in each case was provided by hydrogen and carbon - in the form of polymethylpentyene for the foam case and 2.2-dimethylpropane (i.e., neopentane, C5H12) at 1 atmosphere for the gas case. Dopants of Cl, Ti, Cr and Mn were added to the foams, while Ti and Cr coated carbon fibers were added to the hohlraums - both for isoelectronic x-ray spectroscopic temperature measurements.

Gobby, P. L.; Mitchell, M. A.; Eliott, N. E.; Salazar, M. A.; Fermandez, J. C.; Hsing, W. W.; Moore, J. E.; Gomez, V. M.

403

Plasma jets and plasma bullets  

Microsoft Academic Search

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma

M G Kong; B N Ganguly; R F Hicks

2012-01-01

404

A multistate model of fecundability and sterility.  

PubMed

This paper develops a multistate hazards model for estimating fecundability and sterility from data on waiting times to conception. Important features of the model include separate sterile and nonsterile states, a distinction between preexisting sterility and sterility that begins after initiation of exposure, and log-normally distributed fecundability among nonsterile couples. Application of the model to data on first birth intervals from Taiwan, Sri Lanka, and the Amish shows that heterogeneity in fecundability is statistically significant at most ages, but that preexisting sterility and new sterility are unimportant before age 40. These results suggest that sterility may not be an important determinant of natural fertility until later reproductive ages. PMID:7828764

Wood, J W; Holman, D J; Yashin, A I; Peterson, R J; Weinstein, M; Chang, M C

1994-08-01

405

In situ gas-phase hydrosilylation of plasma-synthesized silicon nanocrystals.  

PubMed

Surface passivation of semiconductor nanocrystals (NCs) is critical in enabling their utilization in novel optoelectronic devices, solar cells, and biological and chemical sensors. Compared to the extensively used liquid-phase NC synthesis and passivation techniques, gas-phase routes provide the unique opportunity for in situ passivation of semiconductor NCs. Herein, we present a method for in situ gas-phase organic functionalization of plasma-synthesized, H-terminated silicon (Si) NCs. Using real-time in situ attenuated total reflection Fourier transform IR spectroscopy, we have studied the surface reactions during hydrosilylation of Si NCs at 160 °C. First, we show that, during gas-phase hydrosilylation of Si NCs using styrene (1-alkene) and acetylene (alkyne), the reaction pathways of the alkenes and alkynes chemisorbing onto surface SiH(x) (x = 1-3) species are different. Second, utilizing this difference in reactivity, we demonstrate a novel pathway to enhance the surface ligand passivation of Si NCs via in situ gas-phase hydrosilylation using the combination of a short-chain alkyne (acetylene) and a long-chain 1-alkene (styrene). The quality of surface passivation is further validated through IR and photoluminescence measurements of Si NCs exposed to air. PMID:21774486

Jariwala, Bhavin N; Dewey, Oliver S; Stradins, Paul; Ciobanu, Cristian V; Agarwal, Sumit

2011-08-03

406

Radiation sterilization of skin allograft  

NASA Astrophysics Data System (ADS)

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 cm2. 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.

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

2009-07-01

407

[ital In] [ital situ] infrared measurements of film and gas properties during the plasma deposition of amorphous hydrogenated silicon  

SciTech Connect

This research has performed preliminary [ital in] [ital situ] Fourier transform infrared (FTIR) measurements during the plasma deposition of amorphous silicon ([ital a]-Si:H). Experiments demonstrate both gas phase and film measurements within a simple SiH[sub 4] plasma reactor using a specially modified FTIR spectrometer. Films are deposited on substrates of either gold (mirror finish) or stainless steel (matte finish). In particular, [ital in] [ital situ] emission/reflection FTIR of the film yields information about surface temperature, film thickness, and film composition. We have measured surface temperature to [plus minus]5 K and detected the onset of poor film growth at a thickness of 500--1000 A using the 2080 cm[sup [minus]1] absorption feature. A simple model for the reflectance of a film on a metal is employed to determine the thickness of the films. [ital In] [ital situ] emission/transmission FTIR of the plasma determines the gas composition and average gas temperature. Measurements show that the silane conversion is [similar to]11% within the plasma region for a typical deposition at 250 [degree]C and roughly doubles for a deposition at room temperature. The FTIR spectra show that most of this converted silane reappears as disilane (Si[sub 2]H[sub 6]). Before starting the plasma, the silane gas is [similar to]30 K cooler than the nominal substrate temperature of 250 [degree]C; starting the plasma raises the average temperature another 20 [degree]C.

Morrison, P.W. Jr.; Haigis, J.R. (Advanced Fuel Research, Inc., East Hartford, Connecticut 06108 (United States))

1993-05-01

408

The effect of gas flow on argon plasma discharge generated with a single-electrode configuration at atmospheric pressure  

SciTech Connect

A long atmospheric-pressure plasma column confined in a dielectric tube is generated in argon with use of a single-electrode configuration driven with a sinusoidal power supply operating at 45 kHz. The electrical characteristics are investigated by means of measuring voltage-current and voltage-power curves at two gas flow states, turbulent and laminar. The gas temperatures of plasma discharge at various gas flow rates are determined by the spectroscopic analysis of OH A-X spectrum. The discussion about effect of gas flow on electrical discharge characteristics is presented and it is found that the heat removal by gas flow plays the most important role in determining its electrical characteristics.

Li Shouzhe; Huang Wentong; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2009-09-15

409

X-ray diagnostic of the heliospheric plasma and interstellar gas  

NASA Astrophysics Data System (ADS)

The new method of a remote diagnostic of the interacting Solar Wind (SW) plasma and neutral heliospheric gas has been recently developed, employing the charge-exchange mechanism of Extreme Ultraviolet (EUV) and X-ray emissions. Physics of collisions between heavy solar wind ions and neutral atoms and molecules from the interstellar, planetary, and cometary gases, is briefly reviewed. The charge-exchange mechanism of X-ray and EUV emissions induced by highly charged SW ions is described in detail. Unique spectra of cascading photons produced in collisions between heavy SW ions and neutral atoms or molecules are demonstrated. Emission spectra of individual SW ions are analyzed and compared with the results of recent laboratory measurements and quantal calculations. The synthetic spectra of the charge-exchange EUV and X-ray emission are constructed for the slow and fast solar wind, interacting with cometary, planetary and interstellar gases. Results of spectral modeling are compared with observational data from ROSAT, EUVE, CHIPS, FUSE, and Chandra satellite telescopes. Contribution of the charge-exchange mechanism to the diffuse X-ray background is evaluated. A remote EUV and X-ray diagnostic of the SW plasma and interstellar gas is discussed.

Kharchenko, V.

2006-09-01

410

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

PubMed

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

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

2003-02-01

411

Convenient headspace gas chromatographic determination of azide in blood and plasma.  

PubMed

Azide in human blood and plasma samples was derivatized with propionic anhydride in a headspace vial without prior sample preparation. The reaction proceeds quickly at room temperature to form propionyl azide. A portion of the headspace was assayed by gas chromatography with a nitrogen-phosphorus detector. In the heated injector of the gas chromatograph, the propionyl azide undergoes thermal rearrangement, forming ethyl isocyanate, which is subsequently chromatographed and detected. Propionitrile was used as the internal standard. The method is linear to at least 20 microg/mL. Limit of quantitation was 0.04 microg/mL, and the within-run coefficient of variation was 5.6% at 1 microg/mL. There was no interference from cyanide. A fatality report in which blood and plasma azide concentrations from a 59-year-old man were monitored for 24 h following the ingestion of an unknown amount of sodium azide is presented. The patient became critically ill after his self-inflicted sodium azide ingestion. He was intubated and treated with vasopressors and aggressive supportive care, including extracorporeal membrane oxygenation therapy, in the intensive care facility but died from neurological brain damage secondary to anoxia. On admission, 1.4 h after ingestion, his azide level was 5.6 microg/mL (blood); shortly thereafter, it had risen to 13.7 microg/mL (plasma) and, subsequently, was projected to have been eliminated by 16.7 h. No azide was detected in the postmortem blood and vitreous humor. PMID:19874663

Meatherall, Robert; Palatnick, Wes

2009-10-01

412

Hot-filament discharge plasma in argon gas at 140 K  

NASA Astrophysics Data System (ADS)

A hot-filament discharge plasma has been created in a double-walled vacuum chamber with the inner wall cooled by liquid nitrogen vapor. The inner brass chamber (16 cm dia. x 30 cm) is wound with copper tubing for cooling. This chamber has two tungsten filaments 10 cm in length oriented axially about 2.5 cm from the wall. Plasma measurements are made using a Pt wire probe. At 300 K, 0.6 mTorr argon in the outer chamber, and 2 mA emission, the electron density is 1 x10^8 cm-3 and the electron temperature is 0.054 eV. At 140 K, the density is 1.6 x10^8 cm-3 and their temperature is 0.11 eV confirming that the electrons are not cooled by elastic collisions with the gas. The floating potential of the probe is -2.4 V at 300 K and -0.6 V at 140 K as a consequence of the ion current to the probe being about doubled at the lower temperature. The higher ion current may be a consequence of charge-exchange collisions producing cold ions that are more easily captured by the probe. These collisions decrease the ion losses to the wall by slowing ions accelerated by the plasma potential. Electron losses are reduced because of the requirement of quasineutrality, thus reduced evaporative cooling of electrons may be the cause of the increased electron temperature in 140 K gas.

Dickson, Shannon; Robertson, Scott

2009-11-01

413

Debris-free laser plasma sources for EUVL based on gas jets  

SciTech Connect

EUV sources for EUVL must not only be bright for throughput, they must also be debris-free to increase condenser longevity. Many schemes to achieve bright, clean sources for EUVL have been studied, including mass-limited targets, cryogenic targets, electric discharges, and electron-beam pumped vapor. Several of these sources show promise, with varying degrees of brightness, debris reduction, and system complexity. We have studied pulsed gas jets, which we find to be relatively simple, debris-free sources when used under appropriate conditions. Under transverse, 1.06 {mu}m irradiation of the jet at incident laser intensities in the range of 10{sup 11}-10{sup 12} Watts/cm{sup 2}, the conversion efficiency into 2{pi} steradians is in the range of 0.3-0.4%, or approximately half the value exhibited by solid Au or W targets under similar conditions. Source sizes in the range of 350 {mu}m x 400 {mu}m can be achieved, as shown in Fig. 2, depending sensitively on both laser and gas jet parameters. One issue that must be overcome in the use of gas jet targets is the requirement that the laser-irradiated plasma be located as far from the jet nozzle as possible to avoid debris generation while maintaining adequate EUV conversion. We will describe conditions under which these criteria are met. Measurements of the reflectance lifetimes of multilayer-coated mirrors placed near the plasma source under these conditions will also be presented. The potential for scaling such sources up to meet the requirements of a commercial EUVL system will be discussed.

Kubiak, G.D.; O`Connell, D.; Krenz, K.D.

1996-03-01

414

US EPA, Pesticide Product Label, STERILIZING GAS ...  

EPA Pesticide Factsheets

... lC d.llll;l~'l". Sh"IIl" !I f'·,lch Ih.: nt"" Iltt" l"\\C' ,1I,>ul,1 hI" IIlll',I!nlc"I'ltlU,I\\ \\\\llh 'l"'lt"1 11'1 Ilfk,·11 nllnUI,", I hc·n,"hd, ,IIt'I"d h" it,ld .,,'"111 ,itlllll>' lite Ifrt>!.dh'n ...

2011-04-14

415

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

Microsoft Academic Search

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

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

2008-01-01

416

Local thermal equilibrium plasma modeling for analyses of gas-phase reactions during reactive-laser ablation  

Microsoft Academic Search

Number densities of atoms, ions, and molecules in plasmas composed of two-element vapor-gas mixtures have been computed assuming local thermal equilibrium. The calculations include the formation of diatomic molecules by chemical reactions between both elements. Temperature range and total number densities of elements have been set to values characteristic for plasmas generated by pulsed-laser ablation of solid targets under low-pressure

J. Hermann; C. Dutouquet

2002-01-01

417

[ital In] [ital situ] infrared measurements of film and gas properties during the plasma deposition of amorphous hydrogenated silicon  

Microsoft Academic Search

This research has performed preliminary [ital in] [ital situ] Fourier transform infrared (FTIR) measurements during the plasma deposition of amorphous silicon ([ital a]-Si:H). Experiments demonstrate both gas phase and film measurements within a simple SiH[sub 4] plasma reactor using a specially modified FTIR spectrometer. Films are deposited on substrates of either gold (mirror finish) or stainless steel (matte finish). In

Philip W. Morrison; J. R. Haigis

1993-01-01

418

Determination of gas temperature and thermometric species in inductively coupled plasmas by emission and diode laser absorption  

Microsoft Academic Search

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

Alexander A Bolshakov; Brett A Cruden; Surendra P Sharma

2004-01-01

419

Determination of gas temperature and thermometric species in inductively coupled plasmas by emission and diode laser absorption  

Microsoft Academic Search

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

Alexander A. Bol'shakov; Brett A. Cruden; Surendra P. Sharma

2004-01-01

420

Simulation of charged-particle beam transport in a gas using a hybrid particle-fluid plasma model  

Microsoft Academic Search

The simulation of charged-particle beam transport in a ?1 Torr gas requires accurate plasma-electron modeling. A simple resistive model, which assumes local energy deposition and a thermal plasma-electron distribution, is inadequate. A hybrid model has been implemented into the particle-in-cell simulation code, iprop (TheipropThree-DimensionalBeamPropagationCode, AMRC-R-966, available from D. Welch, Mission Research Corporation, 1720 Randolph Road SE, Albuquerque, NM 87106, September

D. R. Welch; C. L. Olson; T. W. L. Sanford

1994-01-01

421

Simulation of charged-particle beam transport in a gas using a hybrid particle-fluid plasma model  

Microsoft Academic Search

The simulation of charged-particle beam transport in a [similar to]1 Torr gas requires accurate plasma-electron modeling. A simple resistive model, which assumes local energy deposition and a thermal plasma-electron distribution, is inadequate. A hybrid model has been implemented into the particle-in-cell simulation code, IPROP ([ital The] IPROP [ital Three]-[ital Dimensional] [ital Beam] [ital Propagation] [ital Code], AMRC-R-966, available from D.

D. R. Welch; C. L. Olson; T. W. L. Sanford

1994-01-01

422

Comparison of Vibrational-Rotational Temperature and Excitation Temperature in Ar-Molecular Gas Induction Thermal Plasmas  

Microsoft Academic Search

The carbon dioxide gas was injected into Ar induction thermal plasmas to investigate the plasma-quenching efficiency of CO2 and N2. In the experiments, C2 molecular band spectra and N2+ molecular spectra were found. Theoretical calculation of the radiation intensity for C2 Swan system and N2+ first negative system was carried out as functions of excitation temperature, rotational temperature and vibrational

Tsubasa Uchida; Yasunori Tanaka; Yoshihiko Uesugi

2007-01-01

423

Influence of the gas density on the motion of a free plasma piston in the railgun channel  

Microsoft Academic Search

The influence of the gas density on the acceleration of a plasma armature inside the railgun channel filled with various gases\\u000a (xenon, air, or helium) under atmospheric pressure is investigated experimentally and theoretically. It is shown that, after\\u000a the discharge current has reached a steady value, the velocity of the glowing plasma front ceases to grow and remains constant\\u000a as

B. G. Zhukov; B. I. Reznikov; R. O. Kurakin; S. I. Rozov

2007-01-01

424

Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering  

Microsoft Academic Search

Gas-temperature and velocity profiles at the exit plane of a thermal argon plasma torch have been determined directly from a high-resolution Doppler-shifted line-shape analysis of laser light scattered by the plasma. Peak temperature and velocity values observed were 13 350 K[plus minus]7% and 1100 m s[sup [minus]1][plus minus]3%. Velocities as low as 45 m s[sup [minus]1][plus minus]45% were measured in

S. C. Snyder; L. D. Reynolds; G. D. Lassahn; J. R. Fincke; C. B. Jr. Shaw; R. J. Kearney

1993-01-01

425

Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering  

Microsoft Academic Search

Gas-temperature and velocity profiles at the exit plane of a thermal argon plasma torch have been determined directly from a high-resolution Doppler-shifted line-shape analysis of laser light scattered by the plasma. Peak temperature and velocity values observed were 13 350 K+\\/-7% and 1100 m s-1+\\/-3%. Velocities as low as 45 m s-1+\\/-45% were measured in the fringe of the jet.

S. C. Snyder; L. D. Reynolds; G. D. Lassahn; J. R. Fincke; C. B. Shaw Jr.; R. J. Kearney

1993-01-01

426

The limits of sterility assurance.  

PubMed

Sterility means the absence of all viable microorganisms including viruses. At present, a sterility assurance level (SAL) of 10(-6) is generally accepted for pharmacopoeial sterilization procedures, i.e., a probability of not more than one viable microorganism in an amount of one million sterilised items of the final product. By extrapolating the reduction rates following extreme artificial initial contamination, a theoretical overall performance of the procedure of at least 12 lg increments (overkill conditions) is demanded to verify an SAL of 10(-6). By comparison, other recommendations for thermal sterilization procedures demand only evidence that the difference between the initial contamination and the number of test organisms at the end of the process amount to more than six orders of magnitude. However, a practical proof of the required level of sterility assurance of 10(-6) is not possible. Moreover, the attainability of this condition is fundamentally dubious, at least in non-thermal procedures. Thus, the question is discussed whether the undifferentiated adherence to the concept of sterility assurance on the basis of a single SAL of 10(-6) corresponds with the safety requirements in terms of patient or user safety, costs and energy efficiency. Therefore, in terms of practical considerations, a concept of tiered SALs is recommended, analogous to the comparable and well-established categorization into "High-level disinfection", "Intermediate-level disinfection" and "Low-level disinfection". The determination of such tiered SALs is geared both to the intended application of the sterilized goods, as well as to the characteristics of the products and the corresponding treatment options.In the case of aseptic preparation, filling and production procedures, a mean contamination probability of 10(-3) is assumed. In automated processes, lower contamination rates can be realized. In the case of the production of re-usable medical devices, a reduction of at least 2 lg increments can be achieved through prior cleaning in validated cleaning and disinfecting devices. By chemical disinfection, a further reduction of >/=5 lg increments is achieved. In the case of sterilized surgical instruments, an additional concern is that they lay opened in contaminated air for the duration of the operation, at least in conventionally ventilated operating theaters. Finally, the amount of pathogens necessary to cause an infection must be considered. By logical consideration of all aspects, it seems possible to partially reduce sterility assurance levels without any loss of safety. Proceeding from this, we would like to make the following suggestions for tiered SAL values, adjusted according to the respective sterilization task:SAL 10(-6) for heat-resistant pharmaceutical preparations (parenterals), suggested term: "Pharmaceutical sterilization",SAL 10(-4) for heat-resistant medical devices, suggested term: "High-level sterilization",SAL 10(-3) for heat-sensitive re-usable medical devices, under the precondition of a validated cleaning efficacy of >4 lg increments, suggested term: "Low-level sterilization". PMID:20204091

von Woedtke, Thomas; Kramer, Axel

2008-09-03

427

Plasma nitriding using high H2 content gas mixtures for a cavitation erosion resistant steel  

NASA Astrophysics Data System (ADS)

Plasma nitriding using high H2 content gas mixtures in CA-6NM martensitic stainless steel was studied in the present work. Nitriding was performed in H2 + N2 gas mixtures for 5, 10 and 20% N2, in volume, at 773 K (500 °C), during 2 h. Changes in the surface morphology and nitrided layer constitution were characterized by SEM, XRD, roughness analysis, and nanoindentation technique. Cavitation erosion behavior of the nitrided samples was also investigated by means of a 20 kHz ultrasonic vibrator. The study was emphasized for the three first cavitation stages (incubation, acceleration, and maximum erosion rate stage) of the cumulative erosion–time curve. Results indicate that the gas mixture nitrogen content strongly influences the phases' formation and its distribution on the nitrided layer. Better cavitation erosion resistance which was attributed to the finer and more homogeneous distribution of the nitrided layer phases was verified for samples treated at 5% N2. Otherwise, worse cavitation erosion behavior for samples nitrided at 20% N2 is supposed to be due to the formation of multiphase compound layer constituted by Fe4N + Fe2–3N + CrN, which can infer residual stress in treated surface.

Allenstein, A. N.; Lepienski, C. M.; Buschinelli, A. J. A.; Brunatto, S. F.

2013-07-01

428

Plasma properties of driver gas following interplanetary shocks observed by ISEE-3  

SciTech Connect

Plasma fluid parameters calculated from solar wind and magnetic field data obtained on ISEE 3 were studied to determine the characteristic properties of driver gas following interplanetary shocks. Of 54 shocks observed from August 1978 to February 1980, 9 contained a well defined driver gas that was clearly identifiable by a discontinuous decrease in the average proton temperature across a tangential discontinuity. While helium enhancements were present in all of 9 of these events, only about half of them contained simultaneous changes in the two quantities. Often the He/H ratio changed over a period of minutes. Simultaneous with the drop in proton temperature the helium and electron temperature decreased abruptly. In some cases the proton temperature depression was accompanied by a moderate increase in magnetic field magnitude with an unusually low variance and by an increase in the ratio of parallel to perpendicular temperature. The drive gas usually displayed a bi-directional flow of suprathermal solar wind electrons at higher energies (>137 eV).

Zwickl, R.D.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; Smith, E.J.

1982-01-01

429

Sterile neutrinos at the CNGS  

NASA Astrophysics Data System (ADS)

We study the potential of the CNGS beam in constraining the parameter space of a model with one sterile neutrino separated from three active ones by an Script O(eV2) mass-squared difference, ? mSBL2. We perform our analysis using the OPERA detector as a reference (our analysis can be upgraded including a detailed simulation of the ICARUS detector). We point out that the channel with the largest potential to constrain the sterile neutrino parameter space at the CNGS beam is ?????. The reason for that is twofold: first, the active-sterile mixing angle that governs this oscillation is the less constrained by present experiments; second, this is the signal for which both OPERA and ICARUS have been designed, and thus benefits from an extremely low background. In our analysis we also took into account ????e oscillations. We find that the CNGS potential to look for sterile neutrinos is limited with nominal intensity of the beam, but it is significantly enhanced with a factor 2 to 10 increase in the neutrino flux. Data from both channels allow us, in this case, to constrain further the four-neutrino model parameter space. Our results hold for any value of ? mSBL2gtrsim0.1 eV2, i.e. when oscillations driven by this mass-squared difference are averaged. We have also checked that the bound on ?13 that can be put at the CNGS is not affected by the possible existence of sterile neutrinos.

Donini, Andrea; Maltoni, Michele; Meloni, Davide; Migliozzi, Pasquale; Terranova, Francesco

2007-12-01

430

Bacterial Sterilization Using Cavitating Jet  

NASA Astrophysics Data System (ADS)

In this paper, a new sterilization method using cavitating flow is presented. Water with bacteria was pressurized up to 105 MPa and flushed out through two very small nozzles 0.1-0.31 mm in diameter, where a cavitating jet was generated containing bubbles that collapsed downstream. First, the effects of jet velocity and cavitation number on the sterilization rate of Escherichia coli JCM1649T (E. coli) were examined. The sterilization rate increased with jet velocity. The rate was proportional to the 3rd power of the velocity. All the E. coli cells were killed by three successive treatments at V=355.7 m/s and cavitation number ?=0.154. The sterilization rate has a peak depending on cavitation number at the low-jet-velocity region of less than 300 m/s. An experiment was also performed to compare two types of bacteria, E. coli, as typical Gram-negative bacteria and Bacillus subtilis JCM1465T (B. subtilis), as typical Gram-positive bacteria. Additional tests were performed using Pseudomonas putida JCM13063T, Gram-negative bacteria and Bacillus halodurans JCTM9153, Gram-positive bacteria. The sterilization rate of the Gram-positive bacteria was much lower than that of the Gram-negative bacteria under the same experimental conditions. Gram-positive bacteria have a thicker peptidoglycan layer than Gram-negative bacteria. This may be the reason why B. subtilis is more resistant to the mechanical stress caused by cavitating flow.

Azuma, Yohei; Kato, Hiroharu; Usami, Ron; Fukushima, Tadamasa

431

Gas temperature measurements in a microwave plasma by optical emission spectroscopy under single-wall carbon nanotube growth conditions  

NASA Astrophysics Data System (ADS)

Plasma gas temperatures were measured via in situ optical emission spectroscopy in a microwave CH4-H2 plasma under carbon nanotube (CNT) growth conditions. Gas temperature is an important parameter in controlling and optimizing CNT growth. The temperature has a significant impact on chemical kinetic rates, species concentrations and CNT growth rates on the substrate. H2 rotational temperatures were determined from the Q-branch spectrum of the d\\,^{3}\\Pi _u(0)\\to a\\,^{3}\\Sigma ^{+}_g (0) transition. N2 rotational and vibrational temperatures were measured by fitting rovibrational bands from the N2 emission spectrum of the C 3?u ? B 3?g transition. The N2 rotational temperature, which is assumed to be approximately equal to the translational gas temperature, increases with an increase in input microwave plasma power and substrate temperature. The measured H2 rotational temperatures were not in agreement with the measured N2 rotational temperatures under the CNT growth conditions in this study. The measured N2 rotational temperatures compared with the H2 rotational temperatures suggest the partial equilibration of upper excited state due to higher, 10 Torr, operating pressure. Methane addition in the hydrogen plasma increases the gas temperature slightly for methane concentrations higher than 10% in the feed gas.

Garg, R. K.; Anderson, T. N.; Lucht, R. P.; Fisher, T. S.; Gore, J. P.

2008-05-01

432

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

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

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

2002-01-01

433

Determination of melatonin in pharmaceutical formulations and human plasma by gas chromatography-electron impact mass spectrometry.  

PubMed

A simple and reliable method for gas chromatography-mass spectrometry (GC-MS) has been developed for the determination of melatonin in commercially available tablet formulations and human plasma. The dissolution of the tablets in ethyl acetate was simply obtained by sonication. The filtrate of the resultant solution, after concentration, was derivatized with pentafluoropropionic anhydride (PFPA) and analysed by GC-MS using splitless injection. The linear response range for melatonin was 5-250 ng on column. The same method can be used, with minor modifications, for the determination of melatonin in spiked human plasma in the range 50-1000 pg/mL plasma. PMID:10477902

Covaci, A; Doneanu, C; Aboul-Enein, H Y; Schepens, P

1999-10-01

434

Positive-column plasma studied by fast-flow glow discharge mass spectrometry: Could it be a ``Rydberg gas?''  

NASA Astrophysics Data System (ADS)

Ions created from the fast-flowing positive column plasma of a glow discharge were monitored using a high voltage magnetic sector mass spectrometer. Since the field gradient and sheath potentials created by the plasma inside the source opposed cation transfer, it is inferred that the ions detected were the field-ionized Rydberg species. This is supported by the mass spectral changes which occurred when a negative bias was applied to the sampling aperture and by the contrasting behavior when attached to a quadrupole analyzer. Reaction with H2 (titrated into the flowing plasma) quenched not only the ionization of discharge gas Rydberg atoms but also the passage of electric current through the plasma, without significant changes to the field and sheath potentials. Few “free” ions were present and the lifetimes of the Rydberg atoms detected were much longer than seen in lower pressure experiments, indicating additional stabilization in the plasma environment. The observations support the model of the flowing plasma, given previously [R. S. Mason, P. D. Miller, and I. P. Mortimer, Phys. Rev. E 55, 7462 (1997)] as mainly a neutral Rydberg atom gas, rather than a conventional ion-electron plasma.

Mason, Rod; Miller, Pat; Mortimer, Ifor; Mitchell, David; Dash, Neil

2003-07-01

435

Voluntary sterilization: six lessons learned.  

PubMed

Aspects of sterilization relevant to other reproductive health services include assuring voluntary decision-making, providing counseling services, preventing infection, maintaining clinical safety, reducing the discomfort and pain clients experience, establishing standards and guidelines for care, and providing follow-up care. Both high quality services and good access to those services are needed. A review of international work in more than 50 countries over the past 25 years has yielded the following lessons on how to assure quality voluntary sterilization services: focus on the client, assure informed choice, support providers with training and other needs, build ownership in the community, use technology which is appropriate for the setting, and offer services within an integrated reproductive health program. What has been learned from providing sterilization services can help lead to overall improvements in reproductive health services. Sustainable service delivery systems which are of good quality and achieve desirable results take long-term, steady work. PMID:12321065

Bakamjian, L; Harper, P B

1997-01-01

436

Influence of wall-charge accumulation on the gas dielectric barrier discharge in alternating current plasma display panel  

Microsoft Academic Search

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

Bingang Guo; Wei Wei; Tsutae Shinoda; Chunliang Liu

2007-01-01

437

Inductively Coupled Plasma Reactive Ion Etching of GeSbTe Thin Films in a HBr\\/Ar Gas  

Microsoft Academic Search

Inductively coupled plasma reactive ion etching of GeSbTe (GST) thin films with a photoresist mask was performed using a HBr\\/Ar gas mixture. The etch rate of GST films increased up to 20% HBr concentration and began to decrease with further increase of HBr concentration. The etch profiles were improved with increasing HBr gas concentration. In particular, clean and vertical etch

JANG WOO LEE; HAN NA CHO; SU RYUN MIN; CHEE WON CHUNG

2007-01-01

438

Development of a portable greenhouse gas analyzer based on Penning ionization electron spectroscopy (PIES) in a pulsed glow discharge plasma  

Microsoft Academic Search

A greenhouse gas (GHG) analyzer currently under development at Lenterra, Inc. is described which utilizes Penning ionization electron spectroscopy (PIES) in a glow discharge plasma. A population of helium metastable atoms (2^3S, 19.8 eV) is produced in a pulsed (50 mus duration, 5 kHz rep rate) glow discharge in helium\\/analyte gas mixtures. In the afterglow electrons are produced due to

C. Mark Denning; Vadim Stepaniuk; Valery Sheverev

2009-01-01

439

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Intense charge exchange of laser-plasma ions with the atoms of a pulsed gas jet  

NASA Astrophysics Data System (ADS)

The results of experiments on the interaction of a laser plasma with a pulsed gas jet are presented. The charge exchange of ions with neutral particles was realised for the first time under controllable conditions for a density of the reagents of no less than 1016 cm-3. The resonance pumping of the C3+ ion level with n=3 was observed by spectral methods. The structure of the region of intense charge exchange was determined from plasma photographs. The data obtained suggest that experiments on soft X-ray lasing at a C5+ ion transition are promising.

Antonov, V. M.; Boyarintsev, Y. L.; Melekhov, A. V.; Posukh, V. G.; Ponomarenko, A. G.; Shaikhislamov, I. F.

2007-09-01

440

Portable Ethylene Oxide Sterilization Chamber  

PubMed Central

A portable ethylene oxide sterilization chamber was designed, constructed, and tested for use in the sterilization of embolectomy catheters. The unit can accommodate catheters up to 40 inches (101.6 cm) in length and can be operated for less than 4 cents per cycle. A constant concentration of 500 mg of ethylene oxide per liter of space and holding periods of 4 and 6 hr at 43 and 22 C, respectively, were adequate when tested with B. subtilis spores. The estimated cost of construction was $165.00. If temperature control is unnecessary, the cost is approximately $80.00. Images

Songer, J. R.; Mathis, R. G.

1969-01-01

First Page Previous Page 1 2 3 4 5 6 7