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1

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

2

Plasma Sterilization Technology for Spacecraft Applications  

NASA Technical Reports Server (NTRS)

The application of plasma gas technology to sterilization and decontamination of spacecraft components is considered. Areas investigated include: effective sterilizing ranges of four separate gases; lethal constituents of a plasma environment; effectiveness of plasma against a diverse group of microorganisms; penetrating efficiency of plasmas for sterilization; and compatibility of spacecraft materials with plasma environments. Results demonstrated that plasma gas, specifically helium plasma, is a highly effective sterilant and is compatible with spacecraft materials.

Fraser, S. J.; Olson, R. L.; Leavens, W. M.

1975-01-01

3

Plasma Sterilization Technology for Spacecraft Applications.  

National Technical Information Service (NTIS)

The application of plasma gas technology to sterilization and decontamination of spacecraft components is considered. Areas investigated include: effective sterilizing ranges of four separate gases; lethal constituents of a plasma environment; effectivene...

S. J. Fraser R. L. Olson W. M. Leavens

1975-01-01

4

Sterilization by oxygen plasma  

NASA Astrophysics Data System (ADS)

The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site and it also affects the bulk properties of the polymers. The use of a gas plasma is an elegant alternative sterilization technique. The plasma promotes an efficient inactivation of the micro-organisms, minimises the damage to the materials and presents very little danger for personnel and the environment. Pure oxygen reactive ion etching type of plasmas were applied to inactivate a biologic indicator, the Bacillus stearothermophilus, to confirm the efficiency of this process. The sterilization processes took a short time, in a few minutes the mortality was complete. In situ analysis of the micro-organisms' inactivating time was possible using emission spectrophotometry. The increase in the intensity of the 777.5 nm oxygen line shows the end of the oxidation of the biologic materials. The results were also observed and corroborated by scanning electron microscopy.

Moreira, Adir José; Mansano, Ronaldo Domingues; Andreoli Pinto, Terezinha de Jesus; Ruas, Ronaldo; Zambon, Luis da Silva; da Silva, Mônica Valero; Verdonck, Patrick Bernard

2004-07-01

5

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

6

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

7

Sterilization by gas ovens  

PubMed Central

A forced convection gas-fired oven has been designed which will sterilize a very heavy load of syringes and instruments and containers. It is superior to a gas-fired, infrared, radiant-heated oven which was designed for sterilizing syringes. Images

Patrick, E. A. K.; Wharton, R. H.; Prentis, K.; Signy, A. G.

1961-01-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

9

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

10

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

11

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

12

Atmospheric-pressure plasma decontamination\\/sterilization chamber  

Microsoft Academic Search

An atmospheric-pressure plasma decontamination\\/sterilization chamber is described. The apparatus is useful for decontaminating sensitive equipment and materials, such as electronics, optics and national treasures, which have been contaminated with chemical and\\/or biological warfare agents, such as anthrax, mustard blistering agent, VX nerve gas, and the like. There is currently no acceptable procedure for decontaminating such equipment. The apparatus may also

Hans W. Herrmann; Gary S. Selwyn

2001-01-01

13

Atmospheric-pressure plasma decontamination/sterilization chamber  

DOEpatents

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

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

2001-01-01

14

Cold atmospheric plasma sterilization: from bacteria to biomolecules  

NASA Astrophysics Data System (ADS)

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

Kong, Michael

2009-10-01

15

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

Microsoft Academic Search

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

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

2005-01-01

16

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

NASA Astrophysics Data System (ADS)

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.

2011-01-01

17

Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma  

NASA Astrophysics Data System (ADS)

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

Setareh, Salarieh; Davoud, Dorranian

2013-11-01

18

High-speed sterilization technique using dielectric barrier discharge plasmas in atmospheric humid air  

NASA Astrophysics Data System (ADS)

The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma produced by an ac voltage application of 1 kHz in atmospheric humid air was investigated in order to develop low-temperature, low-cost and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where the air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of Bacillus atrophaeus spores was found to be dependent strongly on the humidity, and was completed within 15 min at a relative humidity of 90 % and a temperature of 30 C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. It is considered that reactive species such as hydroxyl radicals that are effective for the inactivation of Bacillus atrophaeus spores could be produced by the DBD plasma in the humid air. Repetitive micro-pulsed discharge plasmas in the humid air will be applied for the sterilization experiment to enhance the sterilization efficiency.

Miyamae, M.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2010-11-01

19

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

20

Rapid Sterilization of Escherichia coli by Solution Plasma Process  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

21

Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

22

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

NASA Astrophysics Data System (ADS)

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.

2007-06-01

23

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

24

An atmospheric air gas-liquid diffuse discharge excited by bipolar nanosecond pulse in quartz container used for water sterilization  

NASA Astrophysics Data System (ADS)

In this Letter, we report that the air gas-liquid diffuse discharge plasma excited by bipolar nanosecond pulse in quartz container with different bottom structures at atmospheric pressure. Optical diagnostic measurements show that bountiful chemically and biologically active species, which are beneficial for effective sterilization in some areas, are produced. Such diffuse plasmas are then used to treat drinking water containing the common microorganisms (Candida albicans and Escherichia coli). It is found that these plasmas can sterilize the microorganisms efficiently.

Wang, Sen; Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Liu, Zhi-Jie; Tang, Kai; Song, Ying

2013-12-01

25

Low temperature argon plasma sterilization effect on Pseudomonas aeruginosa and its mechanisms  

Microsoft Academic Search

In the present work, low temperature argon plasma was used to sterilize Pseudomonas aeruginosa on PET sheets. The discharge conditions were as follows: power of 30W and gas flux of 20cm3\\/min, and the pressure in the reaction chamber was 6.2Pa. In a self-designed plasma reaction equipment, active species (electron, ion, radical and UV light, etc.) were separated effectively, and the

Liqing Yang; Jierong Chen; Junling Gao

2009-01-01

26

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

27

Sterilization.  

PubMed

Sterilization is accepted as a permanent method of contraception by many couples in the world. Female sterilization is more widely used than male sterilization, but the latter is used by many couples in developed countries. The most widely used methods for female sterilization are simple tubal ligation, electrocautery of the fallopian tubes, and occlusion of the tubes by Hulka or Filshie clips or Falope rings. These procedures may be carried out either by minilaparotomy or by laparoscopy, under local anaesthesia. Sterilization may be performed immediately following pregnancy, or as an interval operation. The effectiveness of female sterilization is high, with failure rates of about 1-2 per 1000 procedures. Immediate complications are few and minor, while there appear to be no serious, long-term adverse effects. It is possible that there is a protective effect against ovarian cancer. Potential new technologies for female sterilization include the use of chemicals, such as quinacrine, for transcervical tubal occlusion, and hysteroscopic methods. Male sterilization is more simple and can readily be performed under local anaesthesia. A new technique originating in China, the no-scalpel technique, has made the procedure even more simple and produces fewer complications such as haematoma. It is possible that the direct injection of plug-forming material into the vas may render the procedure more reversible. Concerns about possible adverse effects of vasectomy on cardiovascular diseases and testicular cancer largely have been dispelled, but a possible weak association between vasectomy and prostatic cancer continues to be studied. PMID:8736725

Wilson, E W

1996-04-01

28

A novel plasma source for sterilization of living tissues  

NASA Astrophysics Data System (ADS)

A source for the production of low-power plasmas at atmospheric pressure, to be used for the nondamaging sterilization of living tissues, is presented. The source, powered by radiofrequency and working with a helium flow, has a specific configuration, studied to prevent the formation of electric arcs dangerous to living matter. It is capable of killing different types of bacteria with a decimal reduction time of 1-2 min; on the contrary, human cells such as conjunctival fibroblasts were found to be almost unharmed by the plasma. A high concentration of OH radicals, likely to be the origin of the sterilizing effect, is detected through their UV emission lines. The effect of the UV and the OH radicals on the fibroblasts was analysed and no significant effects were detected.

Martines, E.; Zuin, M.; Cavazzana, R.; Gazza, E.; Serianni, G.; Spagnolo, S.; Spolaore, M.; Leonardi, A.; Deligianni, V.; Brun, P.; Aragona, M.; Castagliuolo, I.; Brun, P.

2009-11-01

29

[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

30

Long-distance oxygen plasma sterilization: Effects and mechanisms  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

32

The role of chemical sputtering during plasma sterilization of Bacillus atrophaeus  

NASA Astrophysics Data System (ADS)

The inactivation of bacteria by plasma discharges offers the unique benefits of short treatment times, minimal damage to the objects being sterilized and minimal use of hazardous chemicals. Plasmas produce reactive fluxes of ions, atoms and UV photons from any given precursor gas and are expected to be a viable method for such sterilization applications. The plasma based inactivation of harmful biological systems is, however, not yet widely used, because any validation is hampered by the limited knowledge about the interaction mechanisms at the interface between a plasma and a biological system. By using quantified beams of hydrogen atoms, argon ions and UV photons, the treatment of bacteria in a typical argon-hydrogen plasma is mimicked in a very controlled manner. As an example the inactivation of endospores of Bacillus atrophaeus is studied. It is shown that the impact of H atoms alone causes no inactivation of bacteria. Instead, the simultaneous impact of atoms and low energy ions causes a perforation of the endosporic shell. The same process occurs during plasma treatment and explains the efficient inactivation of bacteria.

Opretzka, J.; Benedikt, J.; Awakowicz, P.; Wunderlich, J.; von Keudell, A.

2007-05-01

33

Cold atmospheric plasma sterilization: from bacteria to biomolecules  

Microsoft Academic Search

Although ionized gases have been known to have biological effects for more than 100 years, their impact on the practice in healthcare service became very significant only recently. Today, plasma-based surgical tools are used for tissue reduction and blood coagulation as surgical procedures. Most significant however is the speed at which low-temperature gas plasmas are finding new applications in medicine

Michael Kong

2009-01-01

34

Sterilization and decontamination of medical instruments by low pressure plasma discharges: Application of ternary mixtures  

Microsoft Academic Search

Summary form only given. Application of non-equilibrium plasma discharges for sterilization of medical instruments appeared to be promising alternative to commonly used sterilization techniques. This is due to advantageous and unique properties of plasma discharges allowing highly effective treatment without necessity to use toxic substances and maintaining low temperature conditions favorable for treatment of heat degradable articles. Moreover, it was

O. Kylian; K. Stapelmann; F. Rossi

2008-01-01

35

Use of a low-pressure plasma discharge for the decontamination and sterilization of medical devices  

Microsoft Academic Search

Nonequilibrium low-pressure plasma discharges are extensively studied for their applications in the field of decontamination and sterilization of medical devices. The aim of this contribution is to discuss and demonstrate feasibility of oxygen low-pressure inductively coupled plasma (ICP) discharges for removal of various kinds of biological contamination. We demonstrate the ability of ICP discharges for the sterilization of bacterial spores

François Rossi; Ondrej Kylián; Hubert Rauscher; Douglas Gilliland; Lucel Sirghi

2008-01-01

36

Atmospheric Pressure Plasma Induced Sterilization and Chemical Neutralization  

NASA Astrophysics Data System (ADS)

We are studying chemical neutralization and surface decontamination using atmospheric pressure plasma discharges. The plasma is produced by corona discharge from an array of pins and a ground plane. The array is constructed so that various gases, like argon or helium, can be flowed past the pins where the discharge is initiated. The pin array can be biased using either DC, AC or pulsed discharges. Results indicate that the atmospheric plasma is effective in sterilizing surfaces with biological contaminants like E-coli and bacillus subtilus cells. Exposure times of less than four minutes in an air plasma result in a decrease in live colony counts by six orders of magnitude. Greater exposure times result in a decrease of live colony counts of up to ten orders of magnitude. The atmospheric pressure discharge is also effective in decomposing organic phosphate compounds that are simulants for chemical warfare agents. Details of the decomposition chemistry, by-product formation, and electrical energy consumption of the system will be discussed.

Garate, Eusebio; Evans, Kirk; Gornostaeva, Olga; Alexeff, Igor; Lock Kang, Weng; Wood, Thomas K.

1998-11-01

37

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

38

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

39

Sterilization of bacteria, yeast, and bacterial endospores by atmospheric-pressure cold plasma using helium and oxygen.  

PubMed

Atmospheric-pressure cold plasma (APCP) using helium/oxygen was developed and tested as a suitable sterilization method in a clinical environment. The sterilizing effect of this method is not due to UV light, which is known to be the major sterilization factor of APCP, but instead results from the action of reactive oxygen radicals. Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae deposited on a nitrocellulose filter membrane or Bacillus subtilis spores deposited on polypropylene plates were exposed to helium/oxygen plasma generated with AC input power at 10 kHz, 6 kV. After plasma treatment, nitrocellulose filter membranes were overlaid on fresh solid media and CFUs were counted after incubation overnight. D-values were 18 sec for E. coli, 19 sec for S. aureus, 1 min 55 sec for S. cerevisiae, and 14 min for B. subtilis spores. D-values of bacteria and yeast were dependent on the initial inoculation concentration, while the D-value of B. subtilis spores showed no correlation. When treated cells were observed with a scanning electron microscope, E. coli was more heavily damaged than S. aureus, S. cerevisiae exhibited peeling, and B. subtilis spores exhibited shrunken morphology. Results showed that APCP using helium/oxygen has many advantages as a sterilization method, especially in a clinical environment with conditions such as stable temperature, unlimited sample size, and no harmful gas production. PMID:16820756

Lee, Kyenam; Paek, Kwang-hyun; Ju, Won-Tae; Lee, Yoenhee

2006-06-01

40

Effects of Environmental Humidity and Temperature on Sterilization Efficiency of Dielectric Barrier Discharge Plasmas in Atmospheric Pressure Air  

NASA Astrophysics Data System (ADS)

The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma in atmospheric humid air was investigated in order to develop a low-temperature, low-cost, and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of B. atrophaeus spores was found to be dependent strongly on humidity, and was completed within 15 min at a relative humidity of 90% and a temperature of 30 °C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. The inactivation rates depend on not only relative humidity but also temperature, so that water content in air could determine the generation of reactive species such as hydroxyl radicals that are effective for the inactivation of B. atrophaeus spores.

Kikuchi, Yusuke; Miyamae, Masanori; Nagata, Masayoshi; Fukumoto, Naoyuki

2011-01-01

41

Sterilization and plasma processing of room temperature surfaces with a one atmosphere uniform glow discharge plasma (OAUGDP)  

Microsoft Academic Search

A technique for generating active species with the one atmosphere uniform glow discharge plasma (OAUGDP) has been developed and tested in a wide range of potential plasma processing applications, including the sterilization and decontamination of surfaces. The OAUGDP is a non-thermal plasma with the classical characteristics of a low pressure DC normal glow discharge that operates in air (and other

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

2000-01-01

42

Sterilization of Medical Equipment Using Radicals Produced by Oxygen/Water Vapor RF Plasma  

NASA Astrophysics Data System (ADS)

The sterilization of medical equipment was performed using low-pressure RF discharge plasma. Oxygen radicals as oxidizing materials for sterilization were produced from oxygen or water vapor. The generation of atomic oxygen and OH radicals was confirmed using the light emission spectra of the plasma. The pressure in the discharge region was varied periodically during inactivation in order to produce radicals effectively and to penetrate the produced radicals into tiny gaps. Medium sheets for microbial detection indicated that the decimal reduction value of active bacillus was 5 and 8 min using oxygen plasma and water vapor plasma with ne=109 cm-3, respectively. Biological indicators clarified that the sterilization of bacilli spores was successful for a treatment time of 90 min.

Hayashi, Nobuya; Guan, Weimin; Tsutsui, Shinsuke; Tomari, Tetsushi; Hanada, Yasushi

2006-10-01

43

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

44

Evaluation of chlorine dioxide gas for sterilizing food processing lines  

Microsoft Academic Search

Food processing lines are normally steam sterilized at 121°C for at least 30 minutes to eliminate presence of microorganisms. However with the energy cost rising recently, food companies’ operational costs have tremendously increased. Therefore the needs to find alternative sterilization method, which are less expensive, have arisen. ^ Chlorine dioxide (ClO2) has a long history as sanitizer and\\/or disinfectant (Bernarde

Edwin Sutantio

2008-01-01

45

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

46

Low pressure plasma discharges for the sterilization and decontamination of surfaces  

Microsoft Academic Search

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.

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

2009-01-01

47

Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores  

NASA Astrophysics Data System (ADS)

A nonequilibrium Ar/O2 plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. 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. The decimal reduction time (D values) of the Ar/O2 plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

2007-09-01

48

Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores  

SciTech Connect

A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. 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. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe [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)

2007-09-15

49

Sterilization of microorganisms in silk fabrics by microwave-induced argon plasma treatment at atmospheric pressure  

Microsoft Academic Search

Since many old cultural assets, such as clothes, pictures and books, remain in the state of silk fabrics or papers, it is very difficult as well as important to retain their original form. Microbial contamination induces surface deformations and strength degradation of silk fabrics by invading deeply into the fibers. In this study, the sterilization effects of microwave-induced argon plasma

Dong Jeong Park; Mi Hee Lee; Yeon I Woo; Dong-Wook Han; Jae Bong Choi; Jeong Koo Kim; Soon O. Hyun; Kie-Hyung Chung; Jong-Chul Park

2008-01-01

50

Destruction of Bacterial Biofilms Using Gas Discharge Plasma  

NASA Astrophysics Data System (ADS)

Biofilms are bacterial communities embedded in an exopolysaccharidic matrix with a complex architectural structure. Bacteria in biofilms show different properties from those in free life thus, conventional methods of killing bacteria are often ineffective with biofilms. The use of plasmas potentially offers an alternative to conventional sterilization methods since plasmas contain a mixture of charged particles, chemically reactive species, and UV radiation. 4 and 7 day-old biofilms were produced using two bacterial species: Rhizobium gallicum and Chromobacterium violaceum. Gas discharge plasma was produced by using an AtomfloTM reactor (Surfx Technologies) and bacterial biofilms were exposed to it for different periods of time. Our results show that a 10-minute plasma treatment was able to kill 100% of the cells in most cases. Optical emission spectroscopy was used to study plasma composition which is then correlated with the effectiveness of killing. These results indicate the potentiality of plasma as an alternative sterilization method. Supported by CSuperb.

Abramzon, Nina

2005-03-01

51

Sterilization of medical productsin low-pressure glow discharges  

Microsoft Academic Search

Results are presented from experimental and theoretical studies of the sterilization of medical products by the plasmas of\\u000a dc glow discharges in different gas media. The sterilization efficiency is obtained as a function of discharge parameters.\\u000a The plasma composition in discharges in N2 and O2 is investigated under the operating conditions of a plasma sterilizer. It is shown that free

I. A. Soloshenko; V. V. Tsiolko; V. A. Khomich; A. I. Shchedrin; A. V. Ryabtsev; V. Yu. Bazhenov; I. L. Mikhno

2000-01-01

52

Ternary gas plasma welding torch  

NASA Technical Reports Server (NTRS)

A plasma arc welding torch is discussed. 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 and circulates around the head of the torch adjacent to the electrode tip.

Rybicki, Daniel J. (inventor); Mcgee, William F. (inventor); Waldron, Douglas J. (inventor)

1995-01-01

53

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

PubMed

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

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

2012-08-01

54

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

55

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

PubMed Central

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.

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

2013-01-01

56

Gas injected washer plasma gun  

Microsoft Academic Search

A plasma gun similar in geometry to the washer plasma gun has been operated with gas injected externally. Hydrogen, nitrogen and argon plasmas have been ionised and accelerated to velocities of the order of 107 mm s-1 and densities 1011 mm-3. Higher parameter range is possible with higher electrical input power.

K. K. Jain; P. I. John; A. M. Punithavelu; P. P. Rao

1980-01-01

57

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

58

Plasma ladderlectin concentration following sterile inflammation and Aeromonas salmonicida subsp. salmonicida infection.  

PubMed

Plasma samples obtained from rainbow trout either experimentally infected with Aeromonas salmonicida or injected with either A. salmonicida lipopolysaccharide (LPS) or a commercial A. salmonicida vaccine (Lipogen) were analysed by enzyme immunoassay to evaluate changes in rainbow trout ladderlectin (RTLL) concentrations during the acute phase response (APR). Plasma RTLL concentrations in fish injected with A. salmonicida LPS, vaccine or live A. salmonicida varied over a 10 day period, but did not significantly increase. In contrast, fish experimentally infected with A. salmonicida exhibited a modest, but statistically significant (P < 0.05), decrease in RTLL concentration. These studies demonstrate that RTLL is not detectably induced during the trout APR to sterile inflammation or A. salmonicida infection, but plasma concentration of this protein may be reduced during bacterial infection. PMID:19538251

Young, K M; Czyrny, A; Russell, S; Huber, P; Lumsden, J S

2009-07-01

59

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

PubMed Central

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

Saks?, Mikkel; Jakobsen, Stig S; Saks?, Henrik; Baas, J?rgen; Jakobsen, Thomas; S?balle, Kjeld

2012-01-01

60

Sterilization and Mechanism of Microorganisms on A4 Paper by Dielectric Barrier Discharges Plasma at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

This study investigated the microorganisms' sterilization and mechanism by a DBD plasma device at atmospheric pressure. The device including a transfer system and two roller-electrodes is driven by sine-wave high voltages at frequencies of 15 kHz. Normal A4 papers were used to study the effects of the sterilization on their surfaces by analyzing the number of the living bacteria cells. The state of Escherichia coil's DNA were also measured by agarose gel electrophoresis after sterilization to analyze the inactivation mechanisms. Experimental results indicated that microorganisms on the surface of A4 Papers almost were destroyed while the papers went through the device and there was no any damage of the paper during the process. The main reason engendered bacteria death was due to the double chains of the DNA broken by the plasma.

Xianghong, Jia; Jun, Wan; Jinhua, Yang; Feng, Xu; Shouguo, Wang

2009-10-01

61

The effect of sterilization processes on the bioadhesive properties and surface chemistry of a plasma-polymerized polyethylene glycol film: XPS characterization and L929 cell proliferation tests.  

PubMed

The influence of several sterilization processes (autoclaving, gamma-ray irradiation, ethylene oxide exposure and Ar/H(2) low pressure plasma treatment) on the surface chemistry and the bioadhesive properties of thin films (thickness approximately 20 nm) of plasma-polymerized diethylene glycol dimethyl ether has been studied. X-ray photoelectron spectroscopy (XPS) analysis and cell proliferation tests were used to characterize the surfaces. The XPS results revealed in all cases a change in the surface chemistry of the layer after sterilization, whereas the conservation of non-bioadhesive properties of the coating depends on the type of sterilization process. In particular, the low pressure plasma-based sterilization technique leads to a loss of the non-bioadhesive properties of the plasma coating, whereas the coatings are resistant to the other standard decontamination techniques. This property makes them suitable for biomedical applications, provided that an appropriate sterilization process is selected. PMID:18676191

Brétagnol, Frédéric; Rauscher, Hubert; Hasiwa, Marina; Kylián, Ondrej; Ceccone, Giaccomo; Hazell, Len; Paul, Alan J; Lefranc, Olivier; Rossi, François

2008-11-01

62

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

63

Packaging materials for plasma sterilization with the flowing afterglow of an N2-O2 discharge: damage assessment and inactivation efficiency of enclosed bacterial spores  

NASA Astrophysics Data System (ADS)

In conventional sterilization methods (steam, ozone, gaseous chemicals), after their proper cleaning, medical devices are wrapped/enclosed in adequate packaging materials, then closed/sealed before initiating the sterilization process: these packaging materials thus need to be porous. Gaseous plasma sterilization being still under development, evaluation and comparison of packaging materials have not yet been reported in the literature. To this end, we have subjected various porous packagings used with conventional sterilization systems to the N2-O2 flowing afterglow and also a non-porous one to evaluate and compare their characteristics towards the inactivation of B. atrophaeus endospores deposited on a Petri dish and enclosed in such packagings. Because the sterilization process with the N2-O2 discharge afterglow is conducted under reduced-pressure conditions, non-porous pouches can be sealed only after returning to atmospheric pressure. All the tests were therefore conducted with one end of the packaging freely opened, post-sealing being required. The features of these packaging materials, namely mass loss, resistance, toxicity to human cells as well as some characteristics specific to the plasma method used such as ultraviolet transparency, were examined before and after exposure to the flowing afterglow. All of our results show that the non-porous packaging considered is much more suitable than the conventionally used porous ones as far as ensuring an efficient and low-damage sterilization process with an N2-O2 plasma-afterglow is concerned.

Levif, P.; Séguin, J.; Moisan, M.; Soum-Glaude, A.; Barbeau, J.

2011-10-01

64

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

PubMed

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

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

2013-09-01

65

Two Stage Light Gas Plasma Projectile Accelerator.  

National Technical Information Service (NTIS)

A device for accelerating a projectile to extremely high velocities, composed of a light gas accelerator to impart an initial high velocity to the projectile and a plasma accelerator and compressor receiving the moving projectile and accelerating it to hi...

E. L. Shriver D. W. Jex E. B. Igenbergs

1974-01-01

66

[Suitability of different procedures for the sterilization of microsurgical instruments. A review of current and future procedures].  

PubMed

A review of common methods of sterilization is presented. The principles of operation of steam, hot-air, and gas sterilizers, as well as that of a completely new method which uses H2O2 plasma, are described. The suitability of these methods for sterilizing microsurgical instruments was studied. This paper deals in particular with hot-air sterilization, which is preferred because of the low humidity involved. This method was investigated by recording temperature curves during sterilization. Sterilization with hot steam (autoclaving) has been shown to damage instruments by causing corrosion, to which the types of steel used to make these instruments are highly susceptible. A H2O2 plasma sterilization method is described which operates at low temperatures and with very low humidity. Its suitability for microsurgical instruments has been investigated. PMID:2243473

Draeger, J; Prüter, J W

1990-08-01

67

EDITORIAL: Gas plasmas in biology and medicine  

NASA Astrophysics Data System (ADS)

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

Stoffels, Eva

2006-08-01

68

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

Microsoft Academic Search

Non-equilibrium low pressure-plasma discharges are extensively studied for their high potential in the field of sterilization and decontamination of medical devices. This increased interest in plasma discharges arises from, among other reasons, their capability not only to inactivate bacterial spores but also to eliminate, destroy or remove pathogenic biomolecules and thus to provide a one-step process assuring safety of treated

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

2008-01-01

69

Gas heating mechanisms in capacitively coupled plasmas  

NASA Astrophysics Data System (ADS)

Capacitively coupled plasma (CCP) tools utilized for plasma etching of dielectric features utilize large amounts of power for processing. As a result, neutral gas heats up significantly during processing. The resulting gas density variations across the reactor can affect reaction rates, radical densities, plasma characteristics and uniformity within the reactor. In this paper, results from a two-dimensional computational investigation of an Ar/CF4 CCP discharge incorporating an energy equation solution for all ions and neutrals are discussed. The dominant neutral gas heating process is identified to be elastic collisions with ions while conduction is found to be the major mechanism of heat transport. Some species such as F and CF3 demonstrate higher temperatures than the feedstock gases owing to additional heating via charge-exchange reactions and/or Franck-Condon heating. Typical process parameters such as pressure, frequency of excitation, power and gas composition are varied to investigate their impact on gas temperature. At higher excitation frequency and/or pressure, increased elastic collisions with ions lead to greater heat generation. The heat generated per molecule of the radicals, however, decreases with increase in pressure leading to a decrease in gas temperature. The increase in neutral collision frequencies with pressure also results in the decrease in temperature difference between species in the plasma. As CF4 fraction increases, both the elastic collision cross-section and Franck-Condon heating sources increase, leading to higher gas temperatures.

Agarwal, Ankur; Rauf, Shahid; Collins, Ken

2012-10-01

70

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

2010-03-01

71

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

72

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

73

Male Sterility  

Microsoft Academic Search

\\u000a The control of pollen fertility is central to the production of F1-hybrid seed in self-pollinating crops, and is potentially\\u000a applicable to the containment of transgenes deployed in crop plants. Pollen sterility can be achieved through cytoplasmic\\u000a male sterility (CMS) encoded by the plant mitochondrial genome, or through genic male sterility encoded by the nuclear genome.\\u000a Both routes have been exploited

C. D. Chase; A. Ribarits; E. Heberle-Bors

74

Radiation sterilization  

PubMed Central

The sterilization by radiation of disposable medical items has been investigated. Various vegetative and spore-bearing bacteria have been irradiated and results indicate that 2·5 Mrad can be recommended to give a high degree of sterility. Spores of B. pumilus (E.601) showed such resistance that it might be a suitable test organism for determining the efficiency of a radiation treatment. A high standard of packaging must be demanded for pre-sterilized products.

Darmady, E. M.; Hughes, K. E. A.; Burt, Margaret M.; Freeman, Barbara M.; Powell, D. B.

1961-01-01

75

Sterilization of packed matter by means of low temperature atmospheric pressure plasmas  

Microsoft Academic Search

Summary form only given. The decontamination of material in closed containers by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua, is used for these experiments. Microscopy glass slides were inoculated with Listeria innocua by spraying. The slides were

F. Leipold

2010-01-01

76

Sterilization System  

NASA Technical Reports Server (NTRS)

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

1990-01-01

77

Micro-structured electrode arrays: Plasma based sterilization and coating over a wide pressure range  

Microsoft Academic Search

Micro-structured electrode (MSE) arrays consist of an interlocked comb-like electrode system with micron gap widths. These arrays are capable of generating large area uniform glow discharges up to atmospheric pressure. In order to ignite discharges at atmospheric pressure, this approach using the Paschen similarity law (pd=constant) is established beneath dielectric barrier arrays and plasma jets. The generated electric field strengths

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

2005-01-01

78

Ultrafast plasma dynamics in rare gas clusters  

NASA Astrophysics Data System (ADS)

We study two cases of ultrafast electron plasmas in rare gas clusters. In the first one a pump-probe scenario with two 250 attosecond pulses (40 eV photon energy) is used [1] to generate and probe a plasma of a few electrons in a small Ar13 cluster. We discuss the properties of this minimal plasma. In the second case we subject a rare gas cluster to a regular strong laser pulse (800 nm wavelength). A plasma of cigar shape is ignited in the cluster by some seed atoms with lower ionization potential than those of the cluster. Linear or elliptic polarization of the laser can be applied, only changing the shape of the plasma, which is non-spherical in both cases. This is important to ignite the plasma in the first place, which is an ultrafast process since it does not require nuclear motion [2]. [4pt] [1] Ulf Saalmann, Ionut Georgescu and Jan M. Rost, New J. Phys. 10, 025014 (2008).[0pt] [2] Alexey Mikaberidze, Ulf Saalmann, Jan M. Rost, submitted (2009).

Rost, Jan Michael; Georgesc, Ionut; Mikaberidze, Alexey; Saalmann, Ulf

2009-05-01

79

Endotoxin removal by radio frequency gas plasma (glow discharge)  

NASA Astrophysics Data System (ADS)

Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to < 0.5 EU/ml in sterile water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were repeated after employing 3-minute RFGD treatments sequentially for more than 10 cycles to observe removal of deposited matter that correlated with diminished EU titers. The results showed that 5 cycles, for a total exposure time of 15 minutes to low-temperature gas plasma, was sufficient to reduce endotoxin titers to below 0.05 EU/ml, and correlated with concurrent reduction of major endotoxin reference standard absorption bands at 3391 cm-1, 2887 cm-1, 1646 cm -1 1342 cm-1, and 1103 cm-1 to less than 0.05 Absorbance Units. Band depletion varied from 15% to 40% per 3-minute cycle of RFGD exposure, based on peak-to-peak analyses. In some cases, 100% of all applied biomass was removed within 5 sequential 3-minute RFGD cycles. The lipid ester absorption band expected at 1725 cm-1 was not detectable until after the first RFGD cycle, suggesting an unmasking of the actual bacterial endotoxin membrane induced within the gas plasma environment. Future work must determine the applicability of this low-temperature, quick depyrogenation process to medical devices of more complicated geometry than the flat surfaces tested here.

Poon, Angela

80

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

81

Ethylene Oxide Control Technology Development for Hospital Sterilizers.  

National Technical Information Service (NTIS)

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

A. F. Meiners

1988-01-01

82

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

83

Postpartum Sterilization  

MedlinePLUS

... most often for postpartum sterilization is called tubal ligation. For women who have had a vaginal delivery, ... who have had a cesarean delivery , postpartum tubal ligation can be done through the same abdominal incision ...

84

Effect of Coulomb Collisions on Low Gas Pressure Plasmas  

NASA Astrophysics Data System (ADS)

A recent trend in material processing plasmas is the use of a low gas pressure and high plasma density. In such plasmas, Coulomb collisions among charged particles has been considered to have a significant effect on plasma structure. By use of Bobylev and Nanbu's theory [Phy. Rev. E, 61(2000), 4576], this effect on argon plasmas and oxygen plasmas generated by a capacitive discharge is examined. It is found that the effect is appreciable only for oxygen plasmas.

Nanbu, K.; Furubayashi, T.

2006-05-01

85

Transcervical sterilization.  

PubMed

The transcervical approach to permanent female sterilization has been studied for more than 150 years. Methods for accessing the tubes via this approach include blind, radiological and visual (hysteroscopic) techniques. Modalities for occluding the fallopian tubes include thermal, chemical and mechanical means. Some combination of the approach and the occlusive method define all known procedures. Initial attempts at transcervical sterilization were not widely adopted due to an inability to occlude the tube reliably, resulting in pregnancy and/or high morbidity from the procedure. Quinacrine sterilization is a procedure that is widely used in the developing world, but this has not been taken up by the developed world. There are limitations in diagnosing tubal occlusion with this technique. New methods for transcervical sterilization include the Essure and the Adiana procedures. These methods involve hysteroscopic placement of devices that rely on both mechanical occlusion and stimulation of tissue ingrowth to effect tubal occlusion. These new devices can be delivered to more than 90% of tubes, have very high success rates of pregnancy prevention (>99% in studies to date) and are acceptable to patients. Most importantly, they can be fitted under local anaesthesia in an ambulatory setting. The cost advantages of transcervical sterilization have not yet been investigated. It is possible that such a modality for permanent female sterilization may be demonstrated to be highly cost-effective. PMID:16023892

Abbott, Jason

2005-08-01

86

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

87

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

88

Laparoscopic sterilization.  

PubMed

Laparoscopic female sterilization is still the leading method of family planning for patients who have completed their family. Mechanical methods include clips and rings and are preferred because they are safe and efficient and can be used on a day case basis. Appropriate training ensures improved results with fewer complications. Clips and rings have an improved reversal potential. PMID:10459064

Filshie, M

1999-06-01

89

Gas discharge plasmas are effective in inactivating Bacillus and Clostridium spores.  

PubMed

Bacterial spores are the most resistant form of life and have been a major threat to public health and food safety. Nonthermal atmospheric gas discharge plasma is a novel sterilization method that leaves no chemical residue. In our study, a helium radio-frequency cold plasma jet was used to examine its sporicidal effect on selected strains of Bacillus and Clostridium. The species tested included Bacillus subtilis, Bacillus stearothermophilus, Clostridium sporogenes, Clostridium perfringens, Clostridium difficile, and Clostridium botulinum type A and type E. The plasmas were effective in inactivating selected Bacillus and Clostridia spores with D values (decimal reduction time) ranging from 2 to 8 min. Among all spores tested, C. botulinum type A and C. sporogenes were significantly more resistant to plasma inactivation than other species. Observations by phase contrast microscopy showed that B. subtilis spores were severely damaged by plasmas and the majority of the treated spores were unable to initiate the germination process. There was no detectable fragmentation of the DNA when the spores were treated for up to 20 min. The release of dipicolinic acid was observed almost immediately after the plasma treatment, indicating the spore envelope damage could occur quickly resulting in dipicolinic acid release and the reduction of spore resistance. PMID:22075631

Tseng, Shawn; Abramzon, Nina; Jackson, James O; Lin, Wei-Jen

2012-03-01

90

21 CFR 610.12 - Sterility.  

...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....

2014-04-01

91

Role of plasma electrons in the generation of a gas discharge plasma  

NASA Astrophysics Data System (ADS)

The role of different ionization mechanisms in penning-type gas discharges used to generate an emitting plasma in plasma electron sources is considered. It is shown that, under certain conditions, a substantial contribution to the process of gas ionization is provided by plasma electrons.

Gruzdev, V. A.; Zalesski, V. G.; Rusetski, I. S.

2012-12-01

92

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

93

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

94

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

95

Sterilization of exopolysaccharides produced by deep-sea bacteria: impact on their stability and degradation.  

PubMed

Polysaccharides are highly heat-sensitive macromolecules, so high temperature treatments are greatly destructive and cause considerable damage, such as a great decrease in both viscosity and molecular weight of the polymer. The technical feasibility of the production of exopolysaccharides by deep-sea bacteria Vibrio diabolicus and Alteromonas infernus was previously demonstrated using a bioproduct manufacturing process. The objective of this study was to determine which sterilization method, other than heat sterilization, was the most appropriate for these marine exopolysaccharides and was in accordance with bioprocess engineering requirements. Chemical sterilization using low-temperature ethylene oxide and a mixture of ionized gases (plasmas) was compared to the sterilization methods using gamma and beta radiations. The changes to both the physical and chemical properties of the sterilized exopolysaccharides were analyzed. The use of ethylene oxide can be recommended for the sterilization of polysaccharides as a weak effect on both rheological and structural properties was observed. This low-temperature gas sterilizing process is very efficient, giving a good Sterility Assurance Level (SAL), and is also well suited to large-scale compound manufacturing in the pharmaceutical industry. PMID:21566796

Rederstorff, Emilie; Fatimi, Ahmed; Sinquin, Corinne; Ratiskol, Jacqueline; Merceron, Christophe; Vinatier, Claire; Weiss, Pierre; Colliec-Jouault, Sylvia

2011-01-01

96

Sterilization of Exopolysaccharides Produced by Deep-Sea Bacteria: Impact on Their Stability and Degradation  

PubMed Central

Polysaccharides are highly heat-sensitive macromolecules, so high temperature treatments are greatly destructive and cause considerable damage, such as a great decrease in both viscosity and molecular weight of the polymer. The technical feasibility of the production of exopolysaccharides by deep-sea bacteria Vibrio diabolicus and Alteromonas infernus was previously demonstrated using a bioproduct manufacturing process. The objective of this study was to determine which sterilization method, other than heat sterilization, was the most appropriate for these marine exopolysaccharides and was in accordance with bioprocess engineering requirements. Chemical sterilization using low-temperature ethylene oxide and a mixture of ionized gases (plasmas) was compared to the sterilization methods using gamma and beta radiations. The changes to both the physical and chemical properties of the sterilized exopolysaccharides were analyzed. The use of ethylene oxide can be recommended for the sterilization of polysaccharides as a weak effect on both rheological and structural properties was observed. This low-temperature gas sterilizing process is very efficient, giving a good Sterility Assurance Level (SAL), and is also well suited to large-scale compound manufacturing in the pharmaceutical industry.

Rederstorff, Emilie; Fatimi, Ahmed; Sinquin, Corinne; Ratiskol, Jacqueline; Merceron, Christophe; Vinatier, Claire; Weiss, Pierre; Colliec-Jouault, Sylvia

2011-01-01

97

Anisotropic Etching of n+-Polysilicon Using Beam Plasmas Generated by Gas Puff Plasma Sources  

NASA Astrophysics Data System (ADS)

Generation of pulsed chlorine beam plasmas using a nozzle beam system generated from an electron cyclotron resonance (ECR) discharge plasma source with a high-speed gas puff valve (gas puff plasma source) has been studied. Simulations of gas flow, and measurements of plasma parameters and their etching properties have also been discussed, comparing the experimental results with those of conventional ECR plasmas using an almost identical reactor. The time-averaged electron temperatures around a wafer were lower than those in the ECR plasmas for time-averaged pressure of 0.1-2 mTorr. The instantaneous ion energy distributions of the beam plasmas incident on the wafer had wider high-energy tails than those in the ECR plasmas. Thus, anisotropic etching profiles of n+-polysilicon were obtained at the position of the wafer (Bz˜200 G) where notching phenomena were observed in the ECR plasmas.

Oomori, Tatsuo; Taki, Masakazu; Nishikawa, Kazuyasu; Ootera, Hiroki; Ono, Kouichi

1995-04-01

98

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

99

The Importance of Gas Heating in Inductively Coupled Plasmas  

NASA Technical Reports Server (NTRS)

Recently it has been recognized that the neutral gas in inductively coupled plasma reactors heats up significantly during processing. The resulting gas density variations across the reactor affect reaction rates, radical densities, plasma characteristics, and uniformity within the reactor. A self-consistent model that couples the plasma generation and transport to the gas flow and heating has been developed and used to study CF4 discharges. A Langmuir probe has been used to measure radial profiles of electron density and temperature. The model predictions agree well with the experimental results. As a result of these comparisons along with the poorer performance of the model without the gas-plasma coupling, the importance of gas heating in plasma processing has been verified.

Hash, D. B.; Bose, D.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Sharma, S. P.; Biegel, Bryan (Technical Monitor)

2001-01-01

100

Impact of Gas Heating in Inductively Coupled Plasmas  

NASA Technical Reports Server (NTRS)

Recently it has been recognized that the neutral gas in inductively coupled plasma reactors heats up significantly during processing. The resulting gas density variations across the reactor affect reaction rates, radical densities, plasma characteristics, and uniformity within the reactor. A self-consistent model that couples the plasma generation and transport to the gas flow and heating has been developed and used to study CF4 discharges. A Langmuir probe has been used to measure radial profiles of electron density and temperature. The model predictions agree well with the experimental results. As a result of these comparisons along with the poorer performance of the model without the gas-plasma coupling, the importance of gas heating in plasma processing has been verified.

Hash, D. B.; Bose, D.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Sharma, S. P.; Biegel, Bryan (Technical Monitor)

2001-01-01

101

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

102

Plasma arc welding torch having means for vortexing plasma gas exiting the welding torch  

NASA Technical Reports Server (NTRS)

A plasma arc welding torch is described wherein a plasma gas is directed through the body of the welding torch and out of the body across the tip of the welding electrode disposed at the forward end of the body. The plasma gas is provided with a vortexing motion prior to exiting the body by a vortex motion imparting member which is mounted in an orifice housing member and carried in the forward portion of the torch body. The orifice housing member is provided with an orifice of an predetermined diameter through which the electric arc and the plasma gas exits.

Rybicki, Daniel J. (inventor); Mcgee, William F. (inventor)

1994-01-01

103

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

NASA Astrophysics Data System (ADS)

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

Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo

2014-04-01

104

A CC-SAM, for Coiled Coil-Sterile ? Motif, Domain Targets the Scaffold KSR-1 to Specific Sites in the Plasma Membrane  

PubMed Central

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.

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

2013-01-01

105

Corona discharge plasma reactor for decontamination  

Microsoft Academic Search

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

J. G. Birmingham; P. M. Irving

1998-01-01

106

Cryoradiation sterilization—Contemporary state and outlook  

NASA Astrophysics Data System (ADS)

The new approach of radiation sterilization — cryoradiosterilization with programmed freezing — was developed for pharmaceutical solutions. Both scientific and technical problems are solved, the results are discussed. Programmed freezing of vials with the drug's solutions provides the high stability of soluted components with biological activity at sterilizing irradiation without significant change of sterilization doses. Physical, chemical, biological and pharmacological properties of a lot of drug solutions for injection satisfy official requirements after cryoradiation sterilization treatment. This method seems to be especially important for the protein systems which could be infected by dangerous viruses (VIH, hepatitis B): blood plasma, diagnostic sera, protein preparations manufactured from donor's blood, etc.

Talrose, V. L.; Trofimov, V. I.

1995-02-01

107

Ideal Gas gluon plasma with medium dependent dispersion relation.  

National Technical Information Service (NTIS)

An '' ideal gas '' model with temperature dependent particle mass is constructed for the gluon plasma equation of state. This simple model gives us an example of a system with temperature dependent effective Hamiltonian. To satisfy thermodynamical relatio...

M. I. Gorenstein Shin Nan Yang

1995-01-01

108

Transition of RF internal antenna plasma by gas control  

SciTech Connect

The transition between the capacitively coupled plasma (CCP) and the inductively coupled plasma (ICP) was investigated with the internal radio frequency (RF) multi-turn antenna. The transition between them showed the hysteresis curve. The radiation power and the period of the self-pulse mode became small in proportion to the gas pressure. It was found that the ICP transition occurred by decreasing the gas pressure from 400 Pa.

Hamajima, Takafumi; Yamauchi, Toshihiko; Kobayashi, Seiji; Hiruta, Toshihito; Kanno, Yoshinori [Advanced Institute of Industrial Technology, 1-10-40 HigashiOhi, Shinagawa-ku, Tokyo, 140-0011 (Japan); Japan Atomic Energy Agency, 2-4 Tokai-mura, Naka-gun, Ibaraki-ken, 319-1195 (Japan)

2012-07-11

109

Characterization of a new VHF-CCP for Sterilization  

NASA Astrophysics Data System (ADS)

Plasma sterilization is an upcoming alternative to common sterilization methods. Reduced process times combined with a low treatment temperature lead to proper sterilization and decontamination results even for heat-sensitive materials. The capabilities of plasma sterilization were demonstrated in several laboratory setups. Based on these experiences, a new plasma reactor was developed and realized as capacitive coupled plasma discharge with a variable frequency range between 76 and 80 MHz. The reactor concept is designed to meet industrial needs. Therefore, a specialized chamber design was developed: it is composed of PEEK, a high-performance plastic, and it is shaped like a drawer to make the sterilization process easy and uncomplicated for application. Optical Emission Spectroscopy was performed to obtain detailed information about the plasma parameters. According spectra, intensities and plasma parameters will be presented in comparison to a well established ICP laboratory setup. These data are used for optimization of sterilization efficiency. Furthermore, first microbiological tests were carried out at optimized conditions.

Stapelmann, Katharina; Bibinov, Nikita; Wunderlich, Joachim; Awakowicz, Peter

2009-10-01

110

Gas-jet laser-plasma interaction experiments  

Microsoft Academic Search

Preliminary results of laser-plasma interaction studies at 1.06 and 0.53 microns with gas-jet targets are presented. Stimulated Brillouin backscatter is strong in the 100 microns scale-length plasmas, but sidescatter is weak. Temperature, transport, and absorption measurements are discussed.

F. J. Mayer; M. A. Buoniconto; G. E. Busch; G. C. Castella; G. Charatis; D. Jarrell; R. Schroeder; D. L. Matthews; D. Slater; J. Tarvin; C. Thomas; M. Herbst; B. Ripin

1981-01-01

111

Atmospheric Electrodeless Microwave Plasma-torch for Gas Decomposition  

NASA Astrophysics Data System (ADS)

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) require inexpensive, compact, and reliable systems which efficiently and selectively convert the toxic gas to benign or more treatable products. Environmental clean-up and energy efficiency enhancement utilize plasma generated from air at the atmospheric pressure. Electrodes of the arc plasma torches oxidize very quickly due to the oxygen molecules in air. That is why the conventional thermal plasma torch can not be used in environmental applications. In order to solve this difficult problem, we developed a thermal plasma source operating without electrodes. One of electrodeless torches is the microwave plasma which can produce plasmas in large quantities. We can generate plasma at the atmospheric pressure by making use of magnetrons in microwave-ovens. Most of the magnetrons are operated at the frequency of 2.45GHz. Typical magnetron power of home-microwave oven is about 1kW. Electromagnetic waves from magnetron propagate through a waveguide. Plasma is generated under resonant condition, by initiation of an auxiliary ignition system. The plasma is stabilized by vortex stabilization. The eventual application of this research is in air pollution control. Perfluorocarbon Compounds(PFCs), , , and any other global warming gases from etching and cleaning processes have very long lifetime and high global warming potential. We will conduct an experiment to eliminate global warming gases. FT-IR and QMS will be used to analyze and identify by-products after plasma treatment.

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

2001-10-01

112

[The suitability of commercial bioindicators with spores of B. stearothermophilus for the testing of formaldehyde gas sterilizers].  

PubMed

Commercially available biological indicators with spores of B. stearothermophilus were investigated by the Hygiene-Institutes of Kiel and Lubeck. The objective was to find out if those indicators to which sheep blood was added subsequently correspond to the formaldehyde resistance required by. DIN 58948, part 14 (DIN 58948, part 13). Both working groups determined unanimously that the indicators of one producer showed a resistance too low compared to the remaining biological indicators showing a much higher resistance than required. Even biological indicators manufactured strictly in accordance to the testing standard were more resistant than demanded. This also corresponded to the commercially available untreated spores. On the other hand, practice showed that the biological indicators investigated within this study can be easily killed by formaldehyde sterilizers if they respond to the technical standard. In order to realize the testing of these sterilizers with indicators of a generally accepted resistance we propose either to demand for an equivalently higher formaldehyde resistance or to set up a killing period for the spore resistance from 150 to 240 min until experimentally important data are available. Concerning the blood containing indicators the results of both working groups differed considerably within the limits of formaldehyde efficiency whereas this was not the case with untested commercially available spores. As the addition of thinned blood did not cause an increase in resistance we recommend, in the interest of standardized investigative conditions, not to use it. PMID:1953931

Mecke, P; Christiansen, B; Pirk, A

1991-09-01

113

Synergy effect of heat and UV photons on bacterial-spore inactivation in an N2-O2 plasma-afterglow sterilizer  

NASA Astrophysics Data System (ADS)

As a rule, medical devices (MDs) made entirely from metals and ceramics can withstand, for sterilization purposes, elevated temperatures such as those encountered in autoclaves (moist heat >=120 °C) or Poupinel (Pasteur) ovens (dry heat >=160 °C). This not the case with MDs containing polymers: 70 °C seems to be a limit beyond which their structural and functional integrity will be compromised. Nonetheless, all the so-called low-temperature sterilization techniques, relying essentially on some biocidal chemistry (e.g. ethylene oxide, H2O2, O3), are operated at temperatures close to 65 °C, essentially to enhance the chemical reactivity of the biocidal agent. Based on this fact, we have examined the influence of increasing the temperature of the polystyrene Petri dish containing B. atrophaeus bacterial spores when exposing them to UV radiation coming from an N2-O2 flowing plasma afterglow. We have observed that, for a given UV radiation intensity, the inactivation rate increases with the temperature of the Petri dish, provided heat and UV photons are applied simultaneously, a clear case of synergistic effect. More specifically, it means that (i) simply heating the spores at temperatures below 65 °C without irradiating them with UV photons does not induce mortality; (ii) there is no additional increase in the inactivation rate when the Petri has been pre-heated and then brought back to ambient temperature before the spores are UV irradiated; (iii) no additional inactivation results from post-heating spores previously inactivated with UV radiation. Undoubtedly, the synergistic effect shows up only when the physico-chemical agents (UV photons and temperature) are simultaneously in action.

Boudam, M. K.; Moisan, M.

2010-07-01

114

Modelling ideal gas fluorides laser plasmas  

Microsoft Academic Search

A model of spatially homogeneous ideal gas fluorides discharges is developed for estimation of charge carrier densities, electron energies and drift, and their time dependence is a function of gas composition, partial pressure, geometry and electrical input data. The calculations were based on the Boltzmann equation and the transport equation with the density, impulsion and energy of the electron gas.

Karin Stein

1991-01-01

115

Effects of gas plasma on printed circuit board materials  

Microsoft Academic Search

The project was established to define gas plasma process parameters for printed circuit board cleaning without damage to the substrate. Process parameters of gas flow, wattage, and time are defined for both oxygen and argon treatments. The surface activity changes of plastics and printed circuit board materials are described. A preliminary evaluation of the life (surface activity) of these materials

L. C. Jackson

1978-01-01

116

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.

117

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

118

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

119

Electron energy distribution function control in gas discharge plasmas  

SciTech Connect

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

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

2013-10-15

120

Electron energy distribution function control in gas discharge plasmas  

NASA Astrophysics Data System (ADS)

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

Godyak, V. A.

2013-10-01

121

Analysis of the expanding thermal argon oxygen plasma gas phase  

NASA Astrophysics Data System (ADS)

An expanding thermal argon plasma into which oxygen is injected has been analysed by means of Langmuir and Pitot probe measurements. Information is obtained on the ion density profile and the flow pattern in the downstream plasma. A combination of Langmuir and Pitot probe measurements provide information on the total ion flux generated by the plasma source (cascaded arc). It has been found that the ion diffusion is mainly determined by the background pressure in the expansion vessel and the arc current. The ion density is determined by the total power input into the plasma as well as the gas flow in the plasma source. There is an optimum in the power transfer used for ionization from plasma source to the feed gas. Interaction of oxygen with the plasma results in a decrease in the argon ion density and the plasma beam radius. The recirculation pattern of the downstream plasma has been investigated experimentally using the Pitot probe. Due to the low downstream pressure (10-30 Pa), the conventional compressible Pitot probe theory no longer applies. It is concluded that viscous effects start to play an important role at these low pressures and should be taken into account in the analysis of the Pitot probe measurements.

van Hest, M. F. A. M.; Haartsen, J. R.; van Weert, M. H. M.; Schram, D. C.; van de Sanden, M. C. M.

2003-11-01

122

Microwave Plasma Sources for Gas Processing  

Microsoft Academic Search

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

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

2008-01-01

123

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

PubMed

Producing sterile glass surfaces is of great importance for a wide range of laboratory and medical applications, including in vitro cell culture and tissue engineering. However, sterilization may change the surface properties of glass and thereby affect its use for medical applications, for instance as a substrate for culturing cells. To investigate potential effects of sterilization on glass surface topography, borosilicate glass coverslips were left untreated or subjected to several common sterilization procedures, including low-temperature plasma gas, gamma irradiation and steam. Imaging by atomic force microscopy demonstrated that the surface of untreated borosilicate coverslips features a complex landscape of microislands ranging from 1000 to 3000 nm in diameter and 1 to 3 nm in height. Steam treatment completely removes these microislands, producing a nanosmooth glass surface. In contrast, plasma treatment partially degrades the microisland structure, while gamma irradiation has no effect on microisland topography. To test for possible effects of the nanotopographic structures on cell adhesion, human gingival fibroblasts were seeded on untreated or sterilized glass surfaces. Analyzing fibroblast adhesion 3, 6, and 24 h after cell seeding revealed significant differences in cell attachment and spreading depending on the sterilization method applied. Furthermore, single-cell force spectroscopy revealed a connection between the nanotopographic landscape of glass and the formation of cellular adhesion forces, indicating that fibroblasts generally adhere weakly to nanosmooth but strongly to nanorough glass surfaces. Nanotopographic changes induced by different sterilization methods may therefore need to be considered when preparing sterile glass surfaces for cell culture or biomedical applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2755-2766, 2014. PMID:24027204

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

2014-08-01

124

Gas fueling effect on plasma profile in Heliotron J  

NASA Astrophysics Data System (ADS)

The optimization of gas fueling scenarios has been studied to improve the plasma performance in Heliotron J. Gas fueling effects on the plasma profile are discussed by comparing two fueling methods, a short pulse H2-beam fueling with a supersonic molecular-beam injection (SMBI) technique and a high intensity gas-puff fueling (HIGP) with a conventional gas puff technique. The maximum plasma stored energy Wp after SMBI is about 20% higher than that after HIGP in this NBI-only sustained plasma experiment, where the line-averaged density is almost the same (˜3 × 1019 m-3) for both cases. The electron and ion temperatures in the SMBI case are higher than those are in the HIGP case at the Wp-peak timing. A peaked density profile is observed after SMBI, while it is flat or slightly hollow for the case of HIGP. These observations point out the importance of SMBI fueling for plasma density control to obtain better plasma performance.

Mizuuchi, T.; Lee, H. Y.; Mukai, K.; Yamamoto, K.; Kobayashi, S.; Okada, H.; Yamamoto, S.; Ohshima, S.; Zang, L.; Nagasaki, K.; Minami, T.; Kagawa, T.; Minami, T. Y.; Mizuno, K.; Wada, Y.; Arai, S.; Yashiro, H.; Watada, H.; Hashimoto, K.; Kenmochi, N.; Nagae, Y.; Sha, M.; Nakamura, Y. I.; Kasajima, K.; Nishino, N.; Hosoi, K.; Nakashima, Y.; Nakamura, Y.; Konoshima, S.; Sano, F.

2013-07-01

125

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

126

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

127

Microwave Plasma Sources for Gas Processing  

NASA Astrophysics Data System (ADS)

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

2008-03-01

128

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

129

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

Microsoft Academic Search

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

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

2009-01-01

130

Carbon dioxide as working gas for laboratory plasmas  

NASA Technical Reports Server (NTRS)

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

Kist, R.

1976-01-01

131

Mobility in a strongly coupled dusty plasma with gas  

NASA Astrophysics Data System (ADS)

The mobility of a charged projectile in a strongly coupled dusty plasma is simulated. A net force F, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility-limited velocity up. The mobility ?p=up/F of the projectile's motion is obtained. Two regimes depending on F are identified. In the high-force regime, ?p?F0.23, and the scattering cross section ?s diminishes as up-6/5. Results for ?s are compared with those for a weakly coupled plasma and for two-body collisions in a Yukawa potential. The simulation parameters are based on microgravity plasma experiments.

Liu, Bin; Goree, J.

2014-04-01

132

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

133

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

134

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 ...

135

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

DOEpatents

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

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

2004-10-19

136

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" li]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

137

Gas Effect On Plasma Dynamics Of Laser Ablation Zinc Oxide  

SciTech Connect

In order to synthesis zinc oxide thin films and nanostructures, laser ablation of ZnO target into both vacuum and oxygen atmosphere was performed. The gas effect on the plume dynamics was studied for O{sub 2} pressures varied between 10{sup -2} to 70 mbar. Plasma plume evolution was investigated by ICCD camera fast imaging. The plasma was created by a KrF excimer laser ({lambda} = 248 nm, {tau} = 25 ns) at a fluence of 2 J/cm{sup 2}. The light emitted by the plume was observed along the perpendicular to the ejection direction through a fast intensified charge-coupled device (ICCD). We have found that the plasma dynamics is very affected by the gas pressures. The photographs reveal the stratification of plasma into slow and fast components for 0.5 mbar O{sub 2} pressures and beyond. The photographs also show the apparition of hydrodynamic instabilities which are related to chemical reactions between the plasma and the surrounding gas for a certain range of pressures.

Abdelli-Messaci, S.; Kerdja, T.; Lafane, S.; Malek, S. [Advanced Technology Development Center Haouch-Oukil, B. P. 17, Baba Hassen (Algeria)

2008-09-23

138

Viking heat sterilization - Progress and problems  

NASA Technical Reports Server (NTRS)

The Viking Mars landers to be launched in 1975 will carry experiments in biology, planetology, and atmospheric physics. A terminal dry-heat sterilization process using an inert gas was chosen to meet planetary quarantine requirements and preclude contamination of the biology experiment by terrestrial organisms. Deep sterilization is performed at the component level and terminal surface sterilization at the system level. Solutions to certain component problems relating to sterilization are discussed, involving the gyroscope, tape recorder, battery, electronic circuitry, and outgassing. Heat treatment placed special requirements on electronic packaging, including fastener preload monitoring and solder joints. Chemical and physical testing of nonmetallic materials was performed to establish data on their behavior in heat-treatment and vacuum environments. A Thermal Effects Test Model and a Proof Test Capsule were used. It is concluded that a space vehicle can be designed and fabricated to withstand heat sterilization requirements.

Daspit, L. P.; Cortright, E. M.; Stern, J. A.

1974-01-01

139

Simple Model Analysis of Hysteresis Phenomenon of Gas Discharge Plasma  

NASA Astrophysics Data System (ADS)

The hysteresis and multiple-steady states of gas discharge plasma are analyzed by a simple model of chemical-reaction system. In our analysis the emergence of multiple-steady states is explained by using a fact that a function describing the energy balance has three different real roots. The condition that the function has three roots depends on the ratio of the bulk energy increase to the surface energy loss of plasma. The criterion of taking place of the jump between two steady states is examined in a similar manner to order-disorder transition. The critical parameter contains the non-thermodynamic variables such as conductivity and surface quantities. Stabilities of three obtained solutions are discussed by using linear analysis of differential equations and we find that a root represents a saddle point and other two roots represent stable points. The first step to explain the hysteresis phenomenon in Ar gas discharge plasma is found.

Matsunaga, Yasushi; Kato, Tomokazu

1997-01-01

140

Positron transport: The plasma-gas interface  

SciTech Connect

Motivated by an increasing number of applications, new techniques in the analysis of electron transport have been developed over the past 30 years or so, but similar methods had yet to be applied to positrons. Recently, an in-depth look at positron transport in pure argon gas has been performed using a recently established comprehensive set of cross sections and well-established Monte Carlo simulations. The key novelty as compared to electron transport is the effect of positronium formation which changes the number of particles and has a strong energy dependence. This coupled with spatial separation by energy of the positron swarm leads to counterintuitive behavior of some of the transport coefficients. Finally new results in how the presence of an applied magnetic field affects the transport coefficients are presented.

Marler, J. P. [University of Aarhus, Aarhus C DK-8000 (Denmark); Petrovic, Z. Lj.; Bankovic, A.; Dujko, S.; Suvakov, M.; Malovic, G. [Institute of Physics, P.O. Box 68, 11080 Belgrade (Serbia); Buckman, S. J. [CAMS, RSPhysSE, Australian National University, Canberra 2600 (Australia)

2009-05-15

141

Tailored supersonic gas jets for laser plasma accelerators  

NASA Astrophysics Data System (ADS)

Petawatt class lasers have been used to demonstrate acceleration of electron bunches to ˜1-3GeV energy over distances of ˜10-30mm, an accelerating gradient of ˜100GeV/m. Present gas jets have lengths of only 2-4 mm at densities of 10^19 cm-3, sufficient for self trapping and electron acceleration to energies up to ˜150 MeV. Capillary structures 3 cm long have been used to accelerate beams up to 1 GeV. Several concepts have been suggested that use tailored gas density distributions to enhnace the laser plasma acceleration. Stepped profiles (high density followed by lower density) have been suggested in which the short and dense region acts as a nonlinear lens, followed by the lower density and long plateau in which background electrocn are trapped and accelerated by a nonlinear laser wakefield. Other profiles have been suggested to keep the electrons in phase with the wakefield and thereby increase energy and charge in the bunch. Such tailored gas profiles require innovative supersonic gas nozzles, the design of some of which are described. The nozzle flows are mapped using a laser interferometer. The non-axisymmetric density profiles demand multiple measurements at many angles around the azimuth and tomographic reconstruction techniques. S.Y. Kalmykov et al., Plasma Phys. Control. Fusion 53(2011). W. Rittershofer et al., PHYSICS OF PLASMAS 17, 063104, 2010.

Madden, Robert; Krishnan, Mahadevan; Baudisch, Bastian; Bures, Brian; Wilson-Elliot, Kristi; Coleman, Philip

2012-10-01

142

Modeling of non-thermal plasma in flammable gas mixtures  

NASA Astrophysics Data System (ADS)

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 the effect is strongly dependent on the initial temperature, pressure, and composition of the mixture. Of particular interest is comparison between thermal ignition of a fuel-air mixture and non-thermal plasma initiation of the combustion. Mechanisms of thermal ignition in various fuel-air mixtures have been studied for years, and a number of different mechanisms are known providing an agreement with experiments at various conditions. The problem is -- how to conform thermal chemistry approach to essentially non-equilibrium plasma description. The electric discharge produces much above-equilibrium amounts of chemically active species: atoms, radicals and ions. The point is that despite excess concentrations of a number of species, total concentration of these species is far below concentrations of the initial gas mixture. Therefore, rate coefficients for reactions of these discharge produced species with other gas mixture components are well known quantities controlled by the translational temperature, which can be calculated from the energy balance equation taking into account numerous processes initiated by plasma. A numerical model was developed combining traditional approach of thermal combustion chemistry with advanced description of the plasma kinetics based on solution of electron Boltzmann equation. This approach allows us to describe self-consistently strongly non-equilibrium electric discharge in chemically unstable (ignited) gas. Equations of pseudo-one-dimensional gas dynamics were solved in parallel with a system of thermal chemistry equations, kinetic equations for charged particles (electrons, positive and negative ions), and with the electric circuit equation. The electric circuit comprises power supply, ballast resistor connected in series with the discharge and capacity. Rate coefficients for electron-assisted reactions were calculated from solving the two-term spherical harmonic expansion of the Boltzmann equation. Such an approach allows us to describe influence of thermal chemistry reactions (burning) on the discharge characteristics. Results of comparison between the discharge and thermal ignition effects for mixtures of hydrogen or ethylene with dry air will be reported. Effects of acceleration of ignition by discharge plasma will be analyzed. In particular, the role of singlet oxygen produced effectively in the discharge in ignition speeding up will be discussed.

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

2008-07-01

143

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

144

Gas flow driven by thermal creep in dusty plasma  

NASA Astrophysics Data System (ADS)

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.

2009-10-01

145

Mobility in a strongly coupled dusty plasma with gas.  

PubMed

The mobility of a charged projectile in a strongly coupled dusty plasma is simulated. A net force F, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility-limited velocity up. The mobility ?p=up/F of the projectile's motion is obtained. Two regimes depending on F are identified. In the high-force regime, ?p?F0.23, and the scattering cross section ?s diminishes as up-6/5. Results for ?s are compared with those for a weakly coupled plasma and for two-body collisions in a Yukawa potential. The simulation parameters are based on microgravity plasma experiments. PMID:24827355

Liu, Bin; Goree, J

2014-04-01

146

Determination of pethidine in rabbit plasma by capillary gas chromatography.  

PubMed

A simple and fast gas chromatographic method for the determination of pethidine hydrochloride in rabbit plasma is described and validated. This method is an improvement on the GC method which uses a glass column, and was described previously by Koska et al. [Anaesth. Analg. 60 (1981) 8]. The samples were analysed by a GC 5890 HP system using Rtx-5, fused-silica capillary column linked to a nitrogen-phosphorus ionization detector. Lidocaine hydrochloride was used as the internal standard. Calibration curves were linear within the range 5-200 ng/ml. The limit of quantification was about 5 ng using a 1-ml biological sample and no interference was observed in the blank plasma. The mean recovery of the drug from plasma samples was 95.71+/-2.82%. This procedure turned out to be sensitive and convenient enough for the use in pharmacokinetic studies of pethidine. PMID:11684406

Szkutnik, D; Dyderski, S; Majcher, K

2001-12-01

147

Particle and gas velocity measurements in a dc plasma jet  

SciTech Connect

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 kW. Results obtained at distances between 5 and 150 mm from the nozzle showed the particles to penetrate the plasma jet and attain the gas velocity at about 50 mm from their point of injection. Plasma velocity measurements in the core region of the jet proved to be particularly difficult. Limitations of the LDA system with regard to its spatial resolution and seeding requirements are discussed.

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

1980-01-01

148

Terahertz-Radiation-Enhanced Emission of Fluorescence from Gas Plasma  

SciTech Connect

We report the study of femtosecond laser-induced air plasma fluorescence under the illumination of terahertz (THz) pulses. Semiclassical modeling and experimental verification indicate that time-resolved THz radiation-enhanced emission of fluorescence is dominated by the electron kinetics and the electron-impact excitation of gas molecules or ions. We demonstrate that the temporal waveform of the THz field could be retrieved from the transient enhanced fluorescence, making omnidirectional, coherent detection available for THz time-domain spectroscopy.

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

2009-12-04

149

Flue Gas Cleaning Using a Wet-type Plasma Reactor  

Microsoft Academic Search

Within the last 10 years, various kinds of corona-induced non-thermal plasmas have been investigated in order to remove gaseous pollutants, such as SO2 and NO, from air and exhaust gases. 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

Dong Limin; Han Zhidong; Zhang Xiaohong; Yang Jiaxiang

2006-01-01

150

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

151

Dynamic characteristics of gas-water interfacial plasma under water  

SciTech Connect

Gas-water interfacial plasmas under water were generated in a compact space in a tube with a sandglass-like structure, where two metal wires were employed as electrodes with an applied 35 kHz ac power source. The dynamic behaviors of voltage/current were investigated for the powered electrode with/without water cover to understand the effect of the gas-water interface. It is found that the discharge exhibits periodic pulsed currents after breakdown as the powered electrode is covered with water, whereas the electrical current reveals a damped oscillation with time with a frequency about 10{sup 6} Hz as the powered electrode is in a vapor bubble. By increasing water conductivity, a discharge current waveform transition from pulse to oscillation presents in the water covering case. These suggest that the gas-water interface has a significant influence on the discharge property.

Zheng, S. J.; Zhang, Y. C.; Ke, B.; Ding, F.; Tang, Z. L.; Yang, K.; Zhu, X. D. [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2012-06-15

152

Effect of various gas mixtures on plasma cleaned ceramics. Final report. [Electronic components  

Microsoft Academic Search

Activated gas plasma cleaning efficiencies of various gas mixtures were studied for the preparation of ceramic parts. Differences in the ease of removal of organic residue are shown by Auger analyses for the various gases. A reduction in plasma process time is shown to be possible, and gases are compared with oxygen on the basis of cleaning efficiency. The plasma

1979-01-01

153

High Power Light Gas Helicon Plasma Source For VASMIR  

NASA Technical Reports Server (NTRS)

The VASIMR space propulsion development effort relies on a high power (greater than 10kW) helicon source to produce a dense flowing plasma (H, D and He) target for ion cyclotron resonance (ICR) acceleration of the ions. Subsequent expansion in an expanding magnetic field (magnetic nozzle) converts ion lunetic energy to directed momentum. This plasma source must have critical features to enable an effective propulsion device. First, it must ionize most of the input neutral flux of gas, thus producing a plasma stream with a high degree of ionization for application of ICR power. This avoids propellant waste and potential power losses due to charge exchange. Next, the plasma stream must flow into a region of high magnetic field (approximately 0.5 T) for efficient ICR acceleration. Third, the ratio of input power to plasma flux must be low, providing an energy per ion-electron pair approaching 100 eV. Lastly, the source must be robust and capable of very long life-times (years). In our helicon experiment (VX-10) we have measured a ratio of input gas to plasma flux near 100%. The plasma flows from the helicon region (B approximately 0.1 T) into a region with a peak magnetic field of 0.8 T. The energy input per ion-electron pair has been measured at 300 plus or minus 100 eV. Recent results at Oak Ridge National Laboratory (ORNL) show an enhanced efficiency mode of operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 3.5 kW of input power. An upgrade to a power level of 10 kW is underway. Much of our recent work has been with a Boswell double-saddle antenna design. We are also converting the antenna design to a helical type. With these modifications, we anticipate an improvement in the ionization efficiency. This paper presents the results from scaling the helicon in the VX-10 device from 3.5 to 10 kW. We also compare the operation with a double-saddle to a helical antenna design. Finally, we discuss modeling of these configurations using ORNL's EMIR code.

Squire, J. P.; Chang-Diaz, F. R.; Glover, T. W.; Jacobson, V. T.; McCaskill, G. E.; Winter, D. S.; Baity, F. W.; Carter, M. D.; Goulding, R. H.

2004-01-01

154

Regrets after tubal sterilization.  

PubMed

The tendency to categorize tubal sterilization as an almost trivial procedure may contribute, at least in part, to the fact that a significant minority of women undergo an elective surgical intervention that subsequently they come to regret. These cases may represent a small percentage of the many sterilization operations that are performed each year, yet the fact that tubal sterilization is performed primarily on fit young women for "nonmedical" reasons makes it all the more important that women who will come to regret the procedure are identified and advised against it. It is equally important to remember that such regret after a tubal sterilization will lead increasingly to requests for reversal operations. Sometimes the bases for subsequent regret are almost impossible to predict. It is unrealistic in the extreme to attempt to screen potential candidates for tubal sterilization by asking, "Would you regret this operation if your husband and 3 children were killed in a car crash next month?" Yet, it is possible to anticipate some situations in which subsequent regret may be strong enough to drive a woman to seek sterilization reversal. Abraham et al. have sought differences between 2 groups of women who had either requested a tubal sterilization reversal or else had apparently been satisfied with the procedure. They correctly point out the inherent dangers of interpreting "retrospective data" in 2 basically self-selected groups. Yet, the apparent absence of any longterm followup study of women who have undergone tubal sterilization means that such data provide a valid starting point for debate. Of particular interest is the finding by Abraham et al. that even in their control group 24% of 53 women who had undergone tubal sterilization but not sought a reversal had experienced some regrets at the procedure. The women who sought reversal were more likely at the time of the sterilization operation to have been younger, to have undergone sterilization close to delivery, or to have experienced major life changes after sterilization. 34% of the 32 women in the reversal group did not feel that they had had the major role in the decision to terminate their own reproductive capacity. Abraham et al. conclude that with the development of less traumatic methods of tubal occlusion there is no longer any justification for a hasty decision to sterilize at the time of operative delivery or gynecological surgery, simply to "avoid another operation." The decision to undergo what should still be viewed as a "permanent" loss of reproductive ability requires more leisurely consideration that is afforded during the stresses of childbirth, miscarriage, or abortion. PMID:3724625

Couper-Smartt, J

1986-07-01

155

On the use of gas jet targets for laser plasma interaction physics with nanosecond laser pulses  

Microsoft Academic Search

The implementation of gas jet targets appears to be a very attractive alternative to pre-exploded thin foils targets for relativistic laser plasma interactions. In this article, we report a review of recent results obtained by focusing a nanosecond laser beam onto a gas jet target. The benefit of gas jet targets for the generation of homogeneous and large scale plasmas,

V. Malka

2006-01-01

156

Supersonic gas jets for laser-plasma experiments  

NASA Astrophysics Data System (ADS)

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

Schmid, K.; Veisz, L.

2012-05-01

157

Characterization of the global impact of low temperature gas plasma on vegetative microorganisms  

Microsoft Academic Search

Plasma medicine and also decontamination of bacteria with physical plasmas is a promising new field of life science with huge interest especially for medical applications. Despite numerous successful applications of low temperature gas plasmas in medicine and decontamination, the fundamental nature of the interactions between plasma and microorganisms is to a large extent unknown. A detailed knowledge of these interactions

T. Winter; J. Winter; M. Polak; K. Kusch; U. Mader; R. Sietmann; J. Ehlbeck; K. D. Weltmann; M. Hecker; H. Kusch

2011-01-01

158

Nucleation and growth of Nb nanoclusters during plasma gas condensation  

SciTech Connect

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

2013-06-21

159

Plasma polymerization of an ethylene-nitrogen gas mixture  

NASA Technical Reports Server (NTRS)

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

Hudis, M.; Wydeven, T.

1975-01-01

160

The Boundary Layer Between a Rotating Plasma and a Neutral Gas Blanket.  

National Technical Information Service (NTIS)

The boundary layer situated between a rotating hydrogen plasma of high density and a surrounding neutral gas was investigated by means of electric probes. The measured parameters were the electric field, the plasma density, and the electron temperature. T...

T. Hellsten R. Raggi

1974-01-01

161

Female sterilization. Evidence.  

PubMed

The literature review herein reveals substantial information regarding the safety, efficacy, short-term complications, long-term complications, and noncontraceptive benefits of sterilization. This information should be helpful for providers and potential sterilization candidates. The review also reveals areas where the data are unclear. Points to keep in mind during counseling include the following: The vast majority of women are satisfied with the decision to undergo sterilization. The fact that regret occurs underscores the importance of counseling and adequate individual deliberation before the procedure. In addition to the difficulty and expense associated with sterilization reversal, the woman should thoroughly understand the permanence of the procedure. Although failure is a rare event, it can occur many years after the procedure. Although evidence suggests that hysterectomy rates are higher in sterilized women aged less than 30 to 35 years, it is unlikely that there is a plausible biologic effect of sterilization on hysterectomy risk. An association between tubal sterilization and menstrual cycle changes does not seem valid for changes noted up to 2 years after the procedure. Data are unclear and inconsistent among studies observing women more than 2 years after the procedure. Evidence consistently shows that sterilization is associated with a reduced incidence of ovarian cancer and pelvic inflammatory diseases. Most studies show no effect or improvement of sexual satisfaction after sterilization. Complications during and postprocedure are rare. Sterilization provides no protection against the acquisition of sexually transmitted disease. Patients and their physicians should recognize that sterilized women may need more targeted preventive efforts for health screening and to reduce high-risk behavior than women who use other contraceptive methods. The surgeon's experience and the woman's preferences should govern the ultimate decision regarding the approach and occlusion method. Level II-2 evidence indicates comparable safety between interval laparoscopy and minilaparotomy. Data consistently show that in experienced trained hands, tubal sterilization is safe and highly effective regardless of the approach or occlusive method. Attention to the subtleties of technique seems to be most important in ensuring procedure safety and efficacy. Reanalysis of the CREST data shows that the cumulative failure rate of bipolar coagulation is comparable with the failure rate of unipolar coagulation if a substantial length of tube is adequately coagulated. The data discussed herein can be used to guide management decisions that may increase accessibility and reduce cost of the procedure. Low-resource settings and office settings have maintained an excellent safety record for this procedure through performance of sterilization under local anesthesia. The use of local anesthesia enables a change in procedure location from an inpatient operating room to a free-standing surgical clinic or adequately equipped office. Local anesthesia, with or without preoperative medication, is an excellent option associated with a lower complication risk, reduced cost, and shorter, easier recovery. The surgeon should have specific training in the effective use of local anesthetics, preoperative medications, and management of rare complications in low-resource settings. Little additional research is needed regarding the safety and efficacy of standard sterilization approaches and occlusion methods. There is a need for continued development of nonsurgical methods of sterilization, microlaparoscopic approaches performed in the office setting, and the feasibility and acceptance of service provision by nonspecialist health care providers. The evidence indicates that female sterilization can be performed safely in a variety of resource settings ranging from rural sterilization camps in developing countries to high-tech, resource-rich operating rooms in developed c PMID:11091991

Pati, S; Cullins, V

2000-12-01

162

Feed gas humidity introduced into a MHz atmospheric pressure argon plasma jet affects plasma-generated species and plasma-treated human skin cells  

NASA Astrophysics Data System (ADS)

It is known, that gas humidity is an important parameter in plasma treatment of biological systems under ambient conditions. However, humidity in the feed gas of an atmospheric pressure plasma jet is even more crucial than ambient humidity since humid working gas is transported through the active plasma zone and the water molecules become dissociated. The so produced oxygen/hydrogen species are significant for the active plasma component composition. In this work the effect of feed gas humidity on the plasma, on plasma-treated cell growth medium (RPMI) and subsequently on human skin cells is investigated. It is shown, that already small concentrations of humidity (<1000 ppm) induce changes in the optical emission spectrum of the effluent, increase H2O2 concentration in liquid cell growth medium and inhibit human skin cell proliferation.

Winter, Jörn; Wende, Kristian; Hammer, Malte U.; Tresp, Helena; Iseni, Sylvain; Dünnbier, Mario; Masur, Kai; Weltmann, Klaus-Dieter; Reuter, Stephan

2012-10-01

163

Laser ablated copper plasmas in liquid and gas ambient  

SciTech Connect

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

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

2013-05-15

164

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 ...

165

Auditing radiation sterilization facilities  

NASA Astrophysics Data System (ADS)

The diversity of radiation sterilization systems available today places renewed emphasis on the need for thorough Quality Assurance audits of these facilities. Evaluating compliance with Good Manufacturing Practices is an obvious requirement, but an effective audit must also evaluate installation and performance qualification programs (validation_, and process control and monitoring procedures in detail. The present paper describes general standards that radiation sterilization operations should meet in each of these key areas, and provides basic guidance for conducting QA audits of these facilities.

Beck, Jeffrey A.

166

Hysteroscopic Tubal Sterilization  

PubMed Central

Background Hysteroscopic tubal sterilization is a minimally invasive alternative to laparoscopic tubal ligation for women who want permanent contraception. The procedures involves non-surgical placement of permanent microinserts into both fallopian tubes. Patients must use alternative contraception for at least 3 months postprocedure until tubal occlusion is confirmed. Compared to tubal ligation, potential advantages of the hysteroscopic procedure are that it can be performed in 10 minutes in an office setting without the use of general or even local anesthesia. Objective The objective of this analysis was to determine the effectiveness and safety of hysteroscopic tubal sterilization compared with tubal ligation for permanent female sterilization. Data Sources A standard systematic literature search was conducted for studies published from January 1, 2008, until December 11, 2012. Review Methods Observational studies, randomized controlled trials (RCTs), systematic reviews and meta-analyses with 1 month or more of follow-up were examined. Outcomes included failure/pregnancy rates, adverse events, and patient satisfaction. Results No RCTs were identified. Two systematic reviews covered 22 observational studies of hysteroscopic sterilization. Only 1 (N = 93) of these 22 studies compared hysteroscopic sterilization to laparoscopic tubal ligation. Two other noncomparative case series not included in the systematic reviews were also identified. In the absence of comparative studies, data on tubal ligation were derived for this analysis from the CREST study, a large, multicentre, prospective, noncomparative observational study in the United States (GRADE low). Overall, hysteroscopic sterilization is associated with lower pregnancy rates and lower complication rates compared to tubal ligation. No deaths have been reported for hysteroscopic sterilization. Limitations A lack of long-term follow-up for hysteroscopic sterilization and a paucity of studies that directly compare the two procedures limit this assessment. In addition, optimal placement of the microinsert at the time of hysteroscopy varied among studies. Conclusions Hysteroscopic sterilization is associated with: lower pregnancy rates compared to tubal ligation (GRADE very low) lower complication rates compared to tubal ligation (GRADE very low) no significant improvement in patient satisfaction compared to tubal ligation (GRADE very low) Plain Language Summary Hysteroscopic tubal sterilization is a minimally invasive alternative to conventional tubal ligation for women who want a permanent method of contraception. Both approaches involve closing off the fallopian tubes, preventing the egg from moving down the tube and the sperm from reaching the egg. Tubal ligation is a surgical procedure to tie or seal the fallopian tubes, and it usually requires general anesthesia. In contrast, hysteroscopic tubal sterilization can be performed in 10 minutes in an office setting without general or even local anesthesia. A tiny device called a microinsert is inserted into each fallopian tube through the vagina, cervix, and uterus without surgery. An instrument called a hysteroscope allows the doctor to see inside the body for the procedure. Once the microinserts are in place, scar tissue forms around them and blocks the fallopian tubes. Health Quality Ontario conducted a review of the effectiveness and safety of hysteroscopic tubal sterilization compared to tubal ligation. This review indicates that hysteroscopic tubal sterilization is associated with: lower pregnancy rates compared to tubal ligation lower complication rates compared to tubal ligation no significant improvement in patient satisfaction compared to tubal ligation However, we found a number of limitations to the studies available on hysteroscopic tubal sterilization. Among other concerns, most studies did not include long-term follow-up and only 1 study directly compared hysteroscopic tubal sterilization to tubal ligation.

McMartin, K

2013-01-01

167

MODELLING AND SIMULATION OF SOLITONS AND DISCONTINUITIES IN ADIABATIC AND IDEAL GAS AND ELECROSTATIC PLASMA ONE DIMENSIONAL SYSTEMA  

Microsoft Academic Search

Four models of gas and electrostatic plasma are stu died viz ideal gas and adiabatic gas and ideal plasma and adiabatic plasma. These models are fluid equations (continuity ,momentum and energy) of gas and electrostatic plas ma with initial conditions which give rise to soliton and shock formation and examine the effe cts of the ideal and adiabatic thermodynamic assumptions,

R. NAIDOO

168

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

169

High Power Light Gas Helicon Plasma Source for VASIMR  

NASA Technical Reports Server (NTRS)

In the Advanced Space Propulsion Laboratory (ASPL) helicon experiment (VX-10) we have measured a plasma flux to input gas rate ratio near 100% for both helium and deuterium at power levels up to 10 kW. Recent results at Oak Ridge National Laboratory (ORNL) show enhanced efficiency operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 10 kW of input power. The data here uses a Boswell double-saddle antenna design with a magnetic cusp just upstream of the antenna. Similar to ORNL, for deuterium at near 10 kW, we find an enhanced performance of operation at magnetic fields above the lower hybrid matching condition.

Squire, Jared P.; Chang-Diaz, Franklin R.; Glover, Timothy W.; Jacobson, Verlin T.; Baity, F. Wally; Carter, Mark D.; Goulding, Richard H.

2004-01-01

170

Electron ranaway and ion-ion plasma formation in afterglow low-pressure plasma of oxygen-containing gas mixtures  

NASA Astrophysics Data System (ADS)

Experimental investigation of temporal evolution of charged plasma species in afterglow plasma of oxygen-containing mixtures have been investigated. The probe VAC and the time dependence of the saturation positive and negative particles currents to a probe in a fixed bias voltage were performed. The decay of afterglow low-pressure electronegative gas plasmas take place in two distinct stages (the electron-ion stage, and the ion-ion stage) as it was shown in [1] for pure oxygen. In the first stage, the negative ions are locked within a discharge volume and plasma is depleted of electrons and positive ions. The electron density decay is faster, than exponential, and practically all electrons leave plasma volume during finite time followed by the ion--ion (electron-free) plasma formation. The decay of the ion-ion plasma depends on the presence of detachment. With a large content of electronegative gas (oxygen) in a mixture, when there is a ``detachment particles,'' a small fraction of the electrons appearing as a result of the detachment continue to hold all negative ions in the discharge volume. In this case, the densities of all charged plasma components decay according to the same exponential law with a characteristic detachment time. At a low oxygen content in the gas mixture there is no detachment and plasma decays by an ion--ion ambipolar diffusion mechanism.[4pt][1]. S.A.Gutsev, A.A.Kudryavtsev, V.A.Romanenko. Tech.Phys. 40, 1131, (1995).

Kudryavtsev, Anatoly; Bogdanov, Eugene; Kosykh, Nikolay; Gutsev, Sergey

2012-10-01

171

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

Microsoft Academic Search

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

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

2009-01-01

172

Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua  

Microsoft Academic Search

Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC

Estefanía Noriega; Gilbert Shama; Adriana Laca; Mario Díaz; Michael G. Kong

2011-01-01

173

Effects of surrounding gas on the long laminar argon plasma jet characteristics  

Microsoft Academic Search

Comparative study is performed concerning the characteristics of long laminar argon plasma jets issuing into argon or into air surroundings. It is shown that when argon, instead of air, is used as the surrounding gas, besides pure argon atmosphere can be formed, the mass flow rate of surrounding gas entrained into the plasma jet and the length of jet high-temperature

Dong-Yan Xu; Xi Chen

2005-01-01

174

Positron transport and thermalization - the plasma-gas interface  

NASA Astrophysics Data System (ADS)

Low energy positrons are now used in many fields including atomic physics, material science and medicine [1]. Plasma physics is providing new tools for this research, including Penning-Malmberg buffer-gas traps to accumulate positrons and the use of rotating electric fields (the ``rotating wall'' technique) to compress positrons radially and create tailored beams [1]. These devices (now available commercially), which rely in key instances on positron-neutral interactions, are a convenient way to create plasmas and beams for a variety of applications. A deeper understanding of the relevant cooling and loss mechanisms is required to take full advantage of this technology. This talk focuses on a recent study of positrons in such a tenuous gaseous environment in the presence of an applied electric field [2]. Energy-resolved collision cross sections and a Monte Carlo code modified to include positrionium (Ps) formation are used to obtain transport coefficients and the thermalization and Ps-formation rates. A markedly different type of negative differential conductivity is observed (i.e., not seen in electron systems), due to the non-conservative nature of the Ps-formation process. It is particularly prominent in gases with large, highly energy dependent Ps-formation cross sections. The relevance of these calculations to other positron applications will also be discussed, including a currently planned study of positrons in gaseous water. It is hoped that these calculations will inspire a new generation of positron transport experiments.*Work done in collaboration with Z.Lj. Petrovi'c, A. Bankovi'c, M. Suvakov, G. Malovi'c, S. Dujko, S.J. Buckman. 1. C. M. Surko and R. G. Greaves, Phys. Plasmas 11, 2333-2348 (2004).2. A. Bankovi'c, J. P. Marler, M. Suvakov, G. Malovi'c, and Z. Lj. Petrovi'c, Nucl. Instrum. and Meth. in Phys. Res. B 266, 462-465 (2008).

Marler, Joan

2008-11-01

175

Effects of autoclave sterilization on the physical properties of storage bags and granulocyte function.  

PubMed

Autoclave sterilization altered the leaching of plasticizer, CO2 gas permeability, surface area and the surface wettability of bag films. These changes affected granulocyte cell counts and functions during storage. Four types of polyvinyl chloride bags, with di-(2-ethylhexyl)phthalate (DEHP) or tri-(2-ethylhexyl)trimellitate (TOTM) as plasticizer, with or without treatment by glow discharge (H2), were sterilized with ethylene oxide (EO) or autoclaving (AC). The greatest amounts of plasticizer leached from DEHP-EO bags. TOTM plasticizer did not leach into plasma. CO2 gas permeability was greater with TOTM than DEHP. AC sterilization decreased the surface area of bags. Wettability of film surfaces was greatest with H2-TOTM-EO. After storage in these bags for 24 and 48 h at 22 degrees C, the granulocyte cell counts and functions were greatest in H2-TOTM-EO bags with the nonleaching plasticizer, higher CO2 gas permeability and higher wettable surface due to glow-discharge treatment. The H2-TOTM-EO bag was useful as a granulocyte storage container. PMID:3131963

Miyamoto, M; Sasakawa, S

1988-01-01

176

Paraelectric gas flow accelerator  

NASA Technical Reports Server (NTRS)

A substrate is configured with first and second sets of electrodes, where the second set of electrodes is positioned asymmetrically between the first set of electrodes. When a RF voltage is applied to the electrodes sufficient to generate a discharge plasma (e.g., a one-atmosphere uniform glow discharge plasma) in the gas adjacent to the substrate, the asymmetry in the electrode configuration results in force being applied to the active species in the plasma and in turn to the neutral background gas. Depending on the relative orientation of the electrodes to the gas, the present invention can be used to accelerate or decelerate the gas. The present invention has many potential applications, including increasing or decreasing aerodynamic drag or turbulence, and controlling the flow of active and/or neutral species for such uses as flow separation, altering heat flow, plasma cleaning, sterilization, deposition, etching, or alteration in wettability, printability, and/or adhesion.

Sherman, Daniel M. (Inventor); Wilkinson, Stephen P. (Inventor); Roth, J. Reece (Inventor)

2001-01-01

177

Hybrid Gas/Plasma Simulations Using DSMC with the VORPAL Code.  

National Technical Information Service (NTIS)

We are adding a Direct Simulation Monte Carlo model to the plasma simulations code VORPAL to model dilute (large Knudsen number) gases. This will allow VORPAL to run hybrid simulations of gas/plasma mixtures using the current plasma simulation capabilitie...

W. Wang C. Nieter P. Stoltz J. Cambier

2005-01-01

178

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

NASA Astrophysics Data System (ADS)

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 treatment using an atomic force microscope (AFM). After 5 min. plasma treatment, 90% of cells were inactivated, that is, transformed to non-culturable cells. Results for cell surface morphology and micromechanical properties for plasma treatments lasting from 5 to 60 minutes were obtained and will be presented.

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

2009-03-01

179

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

180

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

NASA Astrophysics Data System (ADS)

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

Mirpour, Shahriar; Ghoranneviss, Mahmood; Shahgoli, Farhad

2011-11-01

181

Enhancement of gas response of ZnO micro-nano structured films through plasma treatment  

Microsoft Academic Search

Films of ZnO micro-nano structures were deposited on quartz substrates and subsequently plasma treated in O2, N2 and CF4. It was found that exposure to oxygen plasma enhanced gas response to ethanol vapor of the ZnO films by a factor 2. The effect of surface plasma treatments on the gas response of the ZnO films was discussed in reference to

Jean-Jacques Delaunay; Kazumasa Yanagisawa; Toshiki Nishino; Ichiro Yamada

2007-01-01

182

Production of centimeter-scale, high-density plasmas with a linear gas jet  

SciTech Connect

A novel linear gas jet has been developed and used to produce centimeter-scale, 10[sup 19] cm[sup [minus]3] electron density plasmas. Long regions of high density are important to many types of experiments, including x-ray laser and laser-plasma interaction studies. This new type of gas jet has been characterized by stimulated Raman backscatter emission from the plasma.

Coverdale, C.A.; Darrow, C.B.; Jones, R.; Sawyer, W.; Crane, J.; Ditmire, T.; Perry, M.D. (Lawrence Livermore National Laboratory, Box 808, Livermore California 94550 (United States)); Filbert, P.C. (Lockeed Research and Development Division, 3251 Hanover Street, Palo Alto, California 94304 (United States))

1995-01-01

183

Karlson ozone sterilizer. Final report  

SciTech Connect

The authors have a functional sterilization system employing ozone as a sterilization agent. This final report covers the work that led to the first medical sterilizer using ozone as the sterilizing agent. The specifications and the final design were set by hospital operating room personnel and public safety standards. Work on kill tests using bacteria, viruses and fungi determined the necessary time and concentration of ozone necessary for sterilization. These data were used in the Karlson Ozone Sterilizer to determine the length of the steps of the operating cycle and the concentration of ozone to be used. 27 references.

Karlson, E.

1984-05-07

184

A coupled plasma dynamics and gas flow model for semiconductor processing  

Microsoft Academic Search

A continuum modeling approach by self-consistently coupling plasma dynamics and gas flow will be presented for the analysis of high density plasma reactors. Experimental data [Khater et. al. JVST-B, 16(2), 1998] shows that gas flow distribution affects the etch rate uniformity even at low pressures (6-20 mTorr) and flow rates (20-70 sccm). This study will investigate the effects of gas

Deepak Bose; T. R. Govindan; M. Meyyappan

1998-01-01

185

Investigation of plasma-dust structures in He-Ar gas mixture  

SciTech Connect

The paper reports on the first experiments with plasma-dust formations in dc gas discharge plasma for a He-Ar mixture. It is shown that the choice of light and heavy gases for the mixture suppresses ion heating in electric field under the conventional conditions of experiments and results in a supersonic jet with high Mach numbers. Distribution functions for drifting ions in the gas mixture are calculated for various mixture concentrations, electric field strengths, and gas pressures.

Maiorov, S. A. [A.M. Prokhorov General Physics Institute of Russian Academy of Sciences, Moscow (Russian Federation); Ramazanov, T. S.; Dzhumagulova, K. N.; Jumabekov, A. N.; Dosbolayev, M. K. [Al Farabi Kazakh National University, IETP, Tole bi 96a, Almaty, 050012 (Kazakhstan)

2008-09-15

186

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

Microsoft Academic Search

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

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

2006-01-01

187

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

188

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

189

Unintended Pregnancy Prevention: Female Sterilization  

MedlinePLUS

... had tubal sterilization. Women whose partners had a vasectomy were enrolled to serve as the comparison group. ... menstrual cycles. In addition, both tubal sterilization and vasectomy are permanent methods of contraception; therefore, pregnancies would ...

190

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

NASA Technical Reports Server (NTRS)

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

1994-01-01

191

Biological Sterilization of Returned Mars Samples  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

192

Hazard and Operability Study of an Ethylene Oxide Sterilizer for National Institute for Occupational Safety and Health.  

National Technical Information Service (NTIS)

A hazard and operability (HAZOP) study was conducted on a sterilizer supplied by compressed gas cylinders of ethylene-oxide (EtO). The sterilizer installation, equipment, and operational procedures were reviewed, and recommendations were developed both sp...

1988-01-01

193

The Advantages of Contract Sterilization  

Microsoft Academic Search

The concept of utilizing contract sterilization of medical devices. The advantages and disadvantages of utilizing contractors for the sterilization of disposable medical devices are presented, including the use of cobalt-60 gamma, electron beam, and ethylene oxide. A general update on the scope, activities, and capabilities of the contract sterilizer is included.

George R. Dietz

1995-01-01

194

ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Modeling of gas discharge plasma  

NASA Astrophysics Data System (ADS)

The condition for the self-maintenance of a gas discharge plasma (GDP) is derived from its ionization balance expressed in the Townsend form and may be used as a definition of a gas discharge plasma in its simplest form. The simple example of a gas discharge plasma in the positive column of a cylindrical discharge tube allows demonstrating a wide variety of possible GDP regimes, revealing a contradiction between simple models used to explain gas discharge regimes and the large number of real processes responsible for the self-maintenance of GDP. The variety of GDP processes also results in a stepwise change of plasma parameters and developing some instabilities as the voltage or discharge current is varied. As a consequence, new forms and new applications of gas discharge arise as technology progresses.

Smirnov, Boris M.

2009-06-01

195

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

196

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

197

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

SciTech Connect

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 [Department of Electronic and Biological Physics, Kwangwoon University, 20 Kwangwon-Ro, Nowon-Gu, Seoul 139-701 (Korea, Republic of)] [Department of Electronic and Biological Physics, Kwangwoon University, 20 Kwangwon-Ro, Nowon-Gu, Seoul 139-701 (Korea, Republic of)

2013-08-15

198

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

199

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

Microsoft Academic Search

Hydrogen, oxygen, and hydrogen peroxide have been measured downstream of an atmospheric pressure humid argon dielectric barrier discharge. The yield of the three species was studied as a function of the discharge power and gas flow rate. Hydrogen peroxide was measured after dissolution into water downstream of the discharge, while hydrogen and oxygen were measured in the gas phase. The

M. J. Kirkpatrick; B. Dodet; E. Odic

200

Uranium plasma emission at gas-core reaction conditions  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

201

Water vapor plasma technology for biomass conversion to synthetic gas  

Microsoft Academic Search

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

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

2011-01-01

202

Sterile neutrino anarchy  

NASA Astrophysics Data System (ADS)

Lepton mixing, which requires physics beyond the Standard Model, is surprisingly compatible with a minimal, symmetryless and unbiased approach, called anarchy. This contrasts with highly involved flavor symmetry models. On the other hand, hints for light sterile neutrinos have emerged from a variety of independent experiments and observations. If confirmed, their existence would represent a groundbreaking discovery, calling for a theoretical interpretation. We discuss anarchy in the two-neutrino eV-scale seesaw framework. The distributions of mixing angles and masses according to anarchy are in agreement with global fits for the active and sterile neutrino parameters. Our minimal and economical scenario predicts the absence of neutrinoless double beta decay and one vanishing neutrino mass, and can therefore be tested in future experiments.

Heeck, Julian; Rodejohann, Werner

2013-02-01

203

Atmospheric pressure resistive barrier cold plasma for biological decontamination  

Microsoft Academic Search

Steady-state atmospheric pressure nonthermal plasmas can splendidly debilitate bacteria in liquids, gases, and on surfaces, as well as can disintegrate hazardous chemicals. The nonthermal resistive barrier gas discharge at atmospheric pressure is currently investigated for low-temperature sterilization purposes. We have carried out electrical, chemical, optical, and biological studies of the discharge, with the intent of identifying the chemically and biologically

Magesh Thiyagarajan; Igor Alexeff; Sriram Parameswaran; Stephen Beebe

2005-01-01

204

[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

2012-01-01

205

Enhancement of gas sensor response of nanocrystalline zinc oxide for ammonia by plasma treatment  

NASA Astrophysics Data System (ADS)

The effect of oxygen plasma treatment on nanocrystalline ZnO thin film based gas sensor was investigated. ZnO thin films were synthesized on alkali-free glass substrates by a sol-gel process. ZnO thin films were treated with oxygen plasma to change the number of vacancies/defects in ZnO. The effect of oxygen plasma on the structural, electrical, optical and gas sensing properties was investigated as a function of plasma treatment time. The results suggest that the microstructure and the surface morphology can be tuned by oxygen plasma treatment. The optical transmission in the visible range varies after the oxygen plasma treatment. Moreover, it is found that the oxygen plasma has significant impact on the electrical properties of ZnO thin films indicating a variation of resistivity. The oxygen plasma treated ZnO thin film exhibits an enhanced sensing response towards NH3 in comparison with that of the as-deposited ZnO sensor. When compared with the as-deposited ZnO film, the sensing response was improved by 50% for the optimum oxygen plasma treatment time of 8 min. The selectivity of 8 min plasma treated ZnO sensor was also examined for an important industrial gas mixture of H2, CH4 and NH3.

Hou, Yue; Jayatissa, Ahalapitiya H.

2014-08-01

206

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

SciTech Connect

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

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

2013-09-15

207

[Sterilization of men].  

PubMed

Male sterilization is the most effective method of contraception next to female sterilization, provided that operative technical errors are avoided and postoperative spermiogram testing is conducted. Primary failures of operative technique, which can lead to legal litigation between patient and doctor, are a) that one side is correctly cut, but on the other side, instead of the vas, a vas-like structure is cut, and b) instead of re-sectioning both the right and left sides, the same vas is cut twice at different points. Simple vasotomy (a single cut) and simple vasectomy with ligation of the vas ends are both unreliable methods. The only reliable operative procedure is vasectomy (removal of a segment of the vas) and tying the vas ends back on themselves (using nonabsorbable material), after previous electrocoagulation of the inner coat of the vas. Statistics show that about 1 in 400 cases remains fertile. [Failure is due to 1) misidentification of at least one vas, or 2) spontaneous recanalization following formation of a sperm granuloma.] Another error with serious consequences is the failure of the physician to inform the patient that even after a correctly performed sterilization sperm may appear in the ejaculate for several months. Other forms of contraception should be used until two control tests confirm a reading of azoospermia in ejaculate taken after a week of abstinence. PMID:6489845

Klosterhalfen, H

1984-09-01

208

Surface Treatment of Polymers with Activated Gas Plasma for Adhesive Bonding.  

National Technical Information Service (NTIS)

Several thermoplastic polymers were treated with activated helium and with activated oxygen. Bond strengths of adhesive-bonded specimens prepared from treated and from untreated coupons were compared. Treatment with activated gas plasma prior to bonding s...

J. R. Hall C. A. L. Westerdahl A. T. Devine M. J. Bodnar

1969-01-01

209

Effects of Xe Gas Content and Total Gas Pressure on the Discharge Characteristics of Colour Plasma Display Panels  

NASA Astrophysics Data System (ADS)

The effects of the Xe gas content and total gas pressure on the discharge characteristics of colour plasma display panels including the sustaining voltage margin, white-field chromaticity, discharge time lag (DTL), discharge current peak, and full-width-at-half-maximum (FWHM) of the discharge current pulse, are experimentally studied. The results indicate that as the Xe gas content in the He-Ne-Xe gas mixture or total pressure increases, the sustaining voltage margin increases, the white-field chromaticity improves, and the discharge current peak has a maximum value, while DTL and FWHM have a minimum value. The mean electron energy in the gas mixture discharge is also calculated through a numerical solution of Boltzmann equation. The experimental results are explained from a view of the mean electron energy variations with the Xe gas content and total gas pressure.

Hu, Wenbo; Han, Mengju; Liang, Zhihu

2006-07-01

210

Effect of atmospheric gas plasmas on cancer cell signaling.  

PubMed

Cancer is one of the most life-threatening diseases with many forms still regarded as incurable. The conventional cancer treatments have unwanted side effects such as the death of normal cells. A therapy that can accurately target and effectively kill tumor cells could address the inadequacies of the available therapies. Atmospheric gas plasmas (AGP) that are able to specifically kill cancerous cells offer a promising alternative approach compared to conventional therapies. AGP have been shown to exploit tumor-specific genetic defects and a recent trial in mice has confirmed its antitumor effects. The mechanism by which the AGP act on tumor cells but not normal cells is not fully understood. A review of the current literature suggests that reactive oxygen species (ROS) generated by AGP induce death of cancer cells by impairing the function of intracellular regulatory factors. The majority of cancer cells are defective in tumor suppressors that interfere normal cell growth pathways. It appears that pro-oncogene or tumor suppressor-dependent regulation of antioxidant/or ROS signaling pathways may be involved in AGP-induced cancer cell death. The toxic effects of ROS are mitigated by normal cells by adjustment of their metabolic pathways. On the other hand, tumor cells are mostly defective in several regulatory signaling pathways which lead to the loss of metabolic balance within the cells and consequently, the regulation of cell growth. This review article evaluates the impact of AGP on the activation of cellular signaling and its importance for exploring mechanisms for safe and efficient anticancer therapies. PMID:23754175

Ishaq, Musarat; Evans, Margaret Meg; Ostrikov, Kostya Ken

2014-04-01

211

Plasma polymerization of fluorinated monomers on mesoporous silica membranes and application to gas permeation  

Microsoft Academic Search

Gas permeation membranes were prepared by exposing multilayered ceramic substrates to low temperature plasmas of C4F8, CHF3 and CF3?CH2F in the presence of argon as carrier gas. Permeation rates for CO2, N2 and He were measured and ideal selectivities were calculated from the permeability ratios. The chemical structure of plasma films was investigated by XPS analysis and transmission infrared spectroscopy.

A. Doucouré; C. Guizard; J. Durand; R. Berjoan; L. Cot

1996-01-01

212

High-power-gas-discharge- and laser-plasma-based EUV sources  

Microsoft Academic Search

In this paper we discuss new results from investigations on high power EUV sources for micro-lithography based on gas discharge produced plasmas and laser produced plasmas. The EUV development is performed at XTREME technologies GmbH, a joint venture of Lambda Physik AG, Goettingen, and Jenoptik LOS GmbH, Jena. For gas discharge EUV sources we report data based on Xenon filled

Frank Flohrer; Kai Gaebel; Diethard Kloepfel; Peter Koehler; Imtiaz Ahmad; S. Goetze; Juergen Kleinschmidt; Vladimir Korobotchko; Jens Ringling; Guido Schriever; Uwe Stamm

2002-01-01

213

Intense microwave pulse propagation through gas breakdown plasmas in a waveguide  

Microsoft Academic Search

High-power microwave pulse-compression techniques are used to generate 2.856 GHz pulses propagated in a TEsub10 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 microsec, and peak powers of a few kW to nearly 100 MW, are

D. P. Byrne

1986-01-01

214

Hysteroscopic Tubal Sterilization  

PubMed Central

Background Hysteroscopic sterilization is a minimally invasive alternative to laparoscopic tubal ligation for women who want permanent contraception. In contrast to the laparoscopic technique, a hysteroscope is used to pass permanent microinserts through the cervix and place them in the fallopian tubes. This procedure does not require local or general anesthesia and can be performed in an office setting. Objectives The objective of this analysis was to determine, based on published literature, the cost-effectiveness of hysteroscopic tubal sterilization (HS) compared with laparoscopic tubal ligation (LS) for permanent female sterilization. Data Sources A systematic literature search was conducted for studies published between January 1, 2008, and December 11, 2012. Review Methods Potentially relevant studies were identified based on the title and abstract. Cost-utility analyses (studies that report outcomes in terms of costs and quality-adjusted life-years) were prioritized for inclusion. When not available, cost-effectiveness, cost-benefit, and cost-consequence analyses were considered. Costing studies were considered in the absence of all other analyses. Results A total of 33 abstracts were identified. Three cost analyses were included. A retrospective chart review from Canada found that HS was $111 less costly than LS; a prospective activity-based cost management study from Italy reported that it was €337 less costly than LS; and the results of an American decision model showed that HS was $1,178 less costly than LS. Limitations All studies had limited applicability to the Ontario health care system due to differences in setting, resource use, and costs. Conclusions Three cost analyses found that, although the HS procedure was more expensive due to the cost of the microinserts, HS was less costly than LS overall due to the shorter recovery time required. Plain Language Summary Hysteroscopic sterilization is a minimally invasive alternative to conventional tubal ligation for women who want a permanent method of contraception. Both approaches involve closing off the fallopian tubes, preventing the egg from moving down the tube and the sperm from reaching the egg. Tubal ligation is a surgical procedure to tie or seal the fallopian tubes, and it usually requires general anesthesia. In contrast, hysteroscopic tubal sterilization can be performed in 10 minutes in an office setting without general or even local anesthesia. A tiny device called a microinsert is inserted into each fallopian tube through the vagina, cervix, and uterus without surgery. An instrument called a hysteroscope allows the doctor to see inside the body for the procedure. Once the microinserts are in place, scar tissue forms around them and blocks the fallopian tubes. Health Quality Ontario commissioned a systematic review of published economic literature to determine whether hysteroscopic sterilization is cost-effective compared to tubal ligation. This review did not find any studies that reported results in terms of both costs and effectiveness or costs and quality-adjusted life-years. We did find 3 costing studies and included them in our review. All of these studies found that when hysteroscopic sterilization was performed as an outpatient procedure, it was less expensive than tubal ligation due to a shorter recovery time. However, none of the studies apply directly to Ontario because of differences in our health care system compared to those in the studies.

2013-01-01

215

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

216

Generation of terahertz radiation by focusing femtosecond bichromatic laser pulses in a gas or plasma  

SciTech Connect

The generation of terahertz radiation by focusing two-frequency femtosecond laser pulses is studied. Focusing is carried out both in an undisturbed gas and in a pre-formed plasma. The energy of the terahertz radiation pulses is shown to reduce significantly in the case of focusing in a plasma. (extreme light fields and their applications)

Chizhov, P A; Volkov, Roman V; Bukin, V V; Ushakov, A A; Garnov, Sergei V; Savel'ev-Trofimov, Andrei B

2013-04-30

217

The interaction of energetic charged particles with gas and boundaries in the particle simulation of plasmas  

Microsoft Academic Search

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

Chul-Hyun Lim

2007-01-01

218

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

219

Hybrid Gas\\/Plasma Simulations using DSMC with the Vorpal Code  

Microsoft Academic Search

Summary form only given. A direct simulation Monte Carlo (DSMC) method is being added to VORPAL to model dilute (large Knudsen number) gases. VORPAL is a multi-dimensional, parallel particle-in-cell (PIC) plasma simulation code that supports a variety of models for both plasma and electromagnetic fields. The addition of the DSMC capabilities will allow VORPAL to run hybrid simulations of gas\\/plasma

Chet Nieter; Wen-Lan Wang; Peter H. Stoltz; Jean-Luc Cambier

2005-01-01

220

A direct catalytic conversion of natural gas to C2+ hydrocarbons by microwave plasma  

Microsoft Academic Search

Methane, the major constituent of natural gas, was converted to higher hydrocarbons by a microwave plasma. The yield of C2+\\u000a products increased from 29.2 % to 42.2% with increasing plasma power and decreasing flow rate of methane. When catalysts were used in the plasma reactor, the selectivities\\u000a of ethylene and acetylene increased, while the yield of C2+ remained constant. Among

Wonihl Cho; YoungSoon Baek; Hyosun Pang; Young Chai Kim

1998-01-01

221

The effects of sterilization, processing and aging on the structure and morphology of medical-grade ultrahigh molecular weight polyethylene for use in total joint replacements  

NASA Astrophysics Data System (ADS)

A pilot study was performed which examined the effects of gamma radiation sterilization after five years aging in air on the structure of ultrahigh molecular weight polyethylene (UHMWPE) for total joint replacements. A sterilized tibial component and a nonsterile block of polymer which had come from the same compression molded batch of material were characterized by differential scanning calorimetry (DSC), density gradient column (DGC), small angle x-ray scattering (SAXS), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). Increases in crystallinity and density were observed for the sterilized component after five years aging in air. A thickening of the lamellae as well as an increase in their tortuosity was seen in the sterilized material. Oxygen uptake occurred in the irradiated specimens. Results indicated that chain scission was the dominant response to gamma irradiation sterilization and aging in air for five years. Material from four different processing conditions was sterilized by: gamma irradiation, electron beam irradiation, ethylene oxide gas, plasma, or not sterilized as a control. Groups were divided into aging environments: air, hyaluronic acid and hydrogen peroxide. Characterization by DSC, DGC, TEM, SAXS and FTIR was performed periodically over a period of one and a half years. Processing conditions had the least effect on the structure and morphology of UHMWPE. Initial increases in oxygen uptake were higher for those materials with higher nascent crystallinities. Trends observed for all materials as a function of sterilization, aging environment and time were similar. Sterilization method and subsequent aging time were the most important factor in examining the structure of UHMWPE. Ethylene oxide gas and plasma did not appear to alter the polymer. Both forms of irradiation resulted in the most changes with time augmenting some effects. Results indicated chain scission dominated in response to radiation and caused a degradation of the polymer. Aging environment had a significant effect on the polymer with hydrogen peroxide leading to the most dramatic changes including embrittlement of the material. A mechanism for the oxidation of the polymer is proposed in which oxygen attacks the amorphous regions leading to strains and the eventual creation of microcracks.

Goldman, Marni

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

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

224

Reduction in the Gas Permeability of Plasma Coatings.  

National Technical Information Service (NTIS)

The article deals with means of reducing the gas permeability of sprayed coatings. A couple of methods of obtaining gas permeable coatings included in this article are: treating a sprayed coating with an agglomeration activator and saturating it with orga...

A. I. Borisenko E. M. Trusova I. M. Grogoreva L. N. Usov

1971-01-01

225

A Microwave Induced Helium Plasma Emission Detector for Gas Chromatography.  

National Technical Information Service (NTIS)

The suitability of the detector for analysis of carbon, fluorine, chlorine, phosphorus and sulfur compounds is investigated. The influence of variations in the microwave power, the helium gas flow, the discharge gas pressure and the observation zone of th...

A. Verweij

1979-01-01

226

Control of the area irradiated by the sheet-type plasma jet in atmospheric pressure  

NASA Astrophysics Data System (ADS)

The sterilization effect has been investigated using the sheet-type plasma jet, which was generated between asymmetric electrodes with dielectric plates in gas flow released into the atmospheric air. In this paper, it is indicated there is a possibility that the plasma jet irradiation area can be controlled only by supplied gases without changing a generator structure. The irradiation area control was evaluated from both the sterilization area size and the oxidizing substances distribution. The oxidizing substance distribution was obtained using the chemical reagent prepared in our laboratory. The width of the sheet-type plasma jet was able to be controlled by N2 addition into He gas. As a result, the width of the sterilization area was able to be controlled within the range of 2 to 12 mm at a constant height without changing the generator structure. On the other hand, the evaluation from the oxidizing substances distribution indicated that the irradiation area cannot be controlled in one direction.

Kawasaki, T.; Kawano, K.; Mizoguchi, H.; Yano, Y.; Yamashita, K.; Sakai, M.; Uchida, G.; Koga, K.; Shiratani, M.

2014-06-01

227

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

228

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

PubMed

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

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

2014-02-01

229

Fullerene-rare gas mixed plasmas in an electron cyclotron resonance ion sourcea)  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

230

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Interaction of laser radiation with a dense gas target  

Microsoft Academic Search

An investigation was made of the interaction of a nanosecond laser pulse with a 'puff' gas target at gas densities sufficient for the formation of a critical-density plasma. The parameters of the laser plasma formed in the central interaction region and at its periphery were determined by x-ray spectroscopic methods. The formation of a plasma channel was observed and it

A. Bartnik; V. M. Dyakin; I. Yu Skobelev; A. Ya Faenov; H. Fiedorowicz; M. Szczurek

1997-01-01

231

Fusion plasma confinement research at the gas dynamic trap  

Microsoft Academic Search

A so called vortex confinement of plasma in axially symmetric mirror device was studied. This recently developed approach enables to significantly reduce transverse particle and heat losses typically caused by MHD instabilities which can be excited in this case. Vortex confinement regime was established by application of different potentials to the radial plasma limiters and end-plates. As a result, the

M. S. Korzhavina; V. V. Prikhodko; E. I. Soldatkina; A. L. Solomakhin; E. I. Pinzhenin; A. V. Lvovsky; A. N. Pushkareva; K. V. Zaytsev

2011-01-01

232

Investigating plasma modifications and gas-surface reactions of titanate-based materials for photoconversion  

NASA Astrophysics Data System (ADS)

Plasmas offer added flexibility for chemists in creating materials with ideal properties. Normally unreactive precursors can be used to etch, deposit and modify surfaces. Plasma treatments of porous and compact TiO2 substrates were explored as a function of plasma precursor, substrate location in the plasma, applied rf power, and plasma pulsing parameters. Continuous wave O2 plasma treatments were found to reduce carbon content and increase oxygen content in the films. Experiments also reveal that Si was deposited throughout the mesoporous network and by pulsing the plasma, Si content and film damage could be eliminated. Nitrogen doping of TiO2 films (N:TiO2) was accomplished by pulsed plasmas containing a range of nitrogen precursors. N:TiO2 films were anatase-phased with up to 34% nitrogen content. Four different nitrogen binding environments were controlled and characterized. The produced N:TiO2 films displayed various colors and three possible mechanisms to explain the color changes are presented. Both O2 treated and N:TiO2 materials were tested in photocatalytic devices. Preliminary results from photocatalytic activities of plasma treated P25 TiO2 powders showed that nitrogen doping treatments hinder photocatalytic activity under UV light irradiation, but silicon deposition can improve it. N:TiO2 materials were tested in photovoltaic devices to reveal improved short-circuit current densities for some plasma-modified films. To understand the gas-phase and surface chemistry involved in producing the N:TiO2 films, NH and NH2 species in pulsed NH 3 plasmas were explored by systematically varying peak plasma power and pulsing duty cycle. Results from these studies using gas phase spectroscopy techniques reveal interconnected trends of gas-phase densities and surface reactions. Gas-phase data from pulsed plasmas with two different types of plasma pulsing reveal diminished or increased densities at short pulses that are explained by plasma pulse initiation and afterglow effects. Overall this work reveals characteristics of the plasma systems explored, knowledge of the resulting materials, and control over plasma etching, deposition, and modification of TiO2 surfaces.

Pulsipher, Daniel J. V.

233

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

234

Cosmology of "visible" Sterile Neutrinos  

NASA Astrophysics Data System (ADS)

We point out that in scenarios with a low reheating temperature TR << 100 MeV at the end of (the last episode of) inflation or entropy production, the abundance of sterile neutrinos becomes largely independent of their coupling to active neutrinos. Thus, cosmological bounds become less stringent than usually assumed, allowing sterile neutrinos to be "visible" in future experiments. For example, the sterile neutrino required by the LSND result does not have any cosmological problem within these scenarios.

Gelmini, Graciela B.

235

[Sterilization of the male].  

PubMed

Vasoresection has great significance as a method of contraception. Next to surgicial sterilization of the female it is the most reliable method of contraception if surgical technical errors are avoided and postoperative speriograms are carried out. According to a review by Leader (2711 cases), 1 patient in 400 remaining capable of procreation must nevertheless be reckoned with. The failure is due to the fact that the surgeon did not identify a vas deferens or a spermatogranuloma led to a spontaneous recanilization. For this reason ths stumps of the vas should be stitched round. The question of electrocoagulation of the intima with ligature of the adventitia also arises. PMID:820974

Klosterhalfen, H

1976-07-01

236

Effect of plasma treatment on the gas sensor with single-walled carbon nanotube paste.  

PubMed

The effect of plasma treatment on the gas sensing properties of screen-printed single-walled carbon nanotube (SWCNT) pastes is reported. The gas sensors, using SWCNT pastes as a sensing material, were fabricated by photolithography and screen printing. The SWCNT pastes were deposited between interdigitated electrodes on heater membrane by screen printing. In order to functionalize the pastes, they were plasma treated using several gases which produce defects caused by reactive ion etching. The Ar and O(2) plasma-treated SWCNT pastes exhibited a large response to NO(2) exposure and the fluorinated gas, such as CF(4) and SF(6), plasma-treated SWCNT pastes exhibited a large response to NH(3) exposure. PMID:22284456

Dong, Ki-Young; Ham, Dae-Jin; Kang, Byung Hyun; Lee, Keunsoo; Choi, Jinnil; Lee, Jin-Woo; Choi, Hyang Hee; Ju, Byeong-Kwon

2012-01-30

237

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

238

Interplay of discharge and gas flow in atmospheric pressure plasma jets  

SciTech Connect

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; Cao Zexian [Beijing National Laboratory for Condensed Matters, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190 (China); Yang Jinglong; He Feng [School of Aerospace, Tsinghua University, Beijing 100084 (China)

2011-05-01

239

High Sensitive Formaldehyde Gas Sensor Prepared by R.F. Induction Plasma Deposition Method  

NASA Astrophysics Data System (ADS)

The present work is concerned on developing high sensitive and high performance SnO2-based gas sensors for detecting indoor air pollutant formaldehyde gas. The film was deposited on an alumina substrate using R.F. Induction Plasma Deposition technique. Physical properties of sensing films were examined by SEM, XRD method. The sensors showed high sensitivity to typical HCHO gas at an extremely low gas concentration of 20 parts-per-billion (ppb) with quick response and recovery time at several minutes. The effect of the doping of various metallic additives on the gas-sensing properties and operating temperature dependency were also investigated in the work.

Shi, Liqin; Gao, Wei; Hasegawa, Yuki; Katsube, Teruaki; Nakano, Mamoru; Nakamura, Kiyozumi

240

Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua.  

PubMed

Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC voltage, excitation frequency and the presence of oxygen in the carrier gas resulted in the greatest inactivation efficiency, and this was confirmed with further studies on chicken muscle and skin. Under optimal conditions, a 10 s treatment gave > 3 log reductions of L. innocua on membrane filters, an 8 min treatment gave 1 log reduction on skin, and a 4 min treatment gave > 3 log reductions on muscle. These results show that the efficacy of gas plasma treatment is greatly affected by surface topography. Scanning electron microscopy (SEM) images of chicken muscle and skin revealed surface features wherein bacteria could effectively be protected from the chemical species generated within the gas plasma. The developments in gas plasma technology necessary for its commercial application to foods are discussed. PMID:21839378

Noriega, Estefanía; Shama, Gilbert; Laca, Adriana; Díaz, Mario; Kong, Michael G

2011-10-01

241

Polishing of Optical Media by Dielectric Barrier Discharge Inert Gas Plasma at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

In this paper, surface smoothing of optical glasses, glass ceramic and sapphire using a low-power dielectric barrier discharge inert gas plasma at atmospheric pressure is presented. For this low temperature treatment method, no vacuum devices or chemicals are required. It is shown that by such plasma treatment the micro roughness and waviness of the investigated polished surfaces were significantly decreased, resulting in a decrease in surface scattering. Further, plasma polishing of lapped fused silica is introduced. Based on simulation results, a plasma physical process is suggested to be the underlying mechanism for initialising the observed smoothing effect.

Gerhard, C.; Weihs, T.; Luca, A.; Wieneke, S.; Viöl, W.

2013-12-01

242

Modification of plasma flows with gas puff in the scrape-off layer of ADITYA tokamak  

SciTech Connect

The parallel Mach numbers are measured at three locations in the scrape-off layer (SOL) plasma of ADITYA tokamak by using Mach probes. The flow pattern is constructed from these measurements and the modification of flow pattern is observed by introducing a small puff of working gas. In the normal discharge, there is an indication of shell structure in the SOL plasma flows, which is removed during the gas puff. The plasma parameters, particle flux and Reynolds stress are also measured in the normal discharge and in the discharge with gas puff. It is observed that Reynolds stress and Mach number are coupled in the near SOL region and decoupled in the far SOL region. The coupling in the near SOL region gets washed away during the gas puff.

Sangwan, Deepak; Jha, Ratneshwar; Brotankova, Jana; Gopalkrishna, M. V. [Institute for Plasma Research, Gandhinagar 382428 (India)] [Institute for Plasma Research, Gandhinagar 382428 (India)

2013-06-15

243

Characterization of the global impact of low temperature gas plasma on vegetative microorganisms.  

PubMed

Plasma medicine and also decontamination of bacteria with physical plasmas is a promising new field of life science with huge interest especially for medical applications. Despite numerous successful applications of low temperature gas plasmas in medicine and decontamination, the fundamental nature of the interactions between plasma and microorganisms is to a large extent unknown. A detailed knowledge of these interactions is essential for the development of new as well as for the enhancement of established plasma-treatment procedures. In the present work we introduce for the first time a growth chamber system suitable for low temperature gas plasma treatment of bacteria in liquid medium. We have coupled the use of this apparatus to a combined proteomic and transcriptomic analyses to investigate the specific stress response of Bacillus subtilis 168 cells to treatment with argon plasma. The treatment with three different discharge voltages revealed not only effects on growth, but also clear evidence of cellular stress responses. B. subtilis suffered severe cell wall stress, which was made visible also by electron microscopy, DNA damages and oxidative stress as a result of exposure to plasma. These biological findings were supported by the detection of reactive plasma species by OES measurements. PMID:21751354

Winter, Theresa; Winter, Jörn; Polak, Martin; Kusch, Kathrin; Mäder, Ulrike; Sietmann, Rabea; Ehlbeck, Jörg; van Hijum, Sacha; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

2011-09-01

244

Enhancement of gas response of ZnO micro-nano structured films through plasma treatment  

NASA Astrophysics Data System (ADS)

Films of ZnO micro-nano structures were deposited on quartz substrates and subsequently plasma treated in O2, N2 and CF4. It was found that exposure to oxygen plasma enhanced gas response to ethanol vapor of the ZnO films by a factor 2. The effect of surface plasma treatments on the gas response of the ZnO films was discussed in reference to surface morphology observed by high-magnification SEM and surface chemical state determined by XPS. SEM observation revealed that O2 plasma treatment induced less surface roughening than N2 and CF4 plasmas, in agreement with the view that O2 plasma should reduce preferential sputtering. Deconvolution of the O 1s X-ray photoelectron peak indicated an increase in the Zn-O bond surface density relatively to O-H bond density for the O2 plasma treated surface, whereas the O-H bond surface density was increased relatively to the Zn-O bond density for the N2 and CF4 plasma treated films. The O2 plasma was found to partially clean the surface from hydroxyl groups and to expose more Zn cations, which might have caused the enhancement of sensor response by increasing the density of active sites for oxidation/reduction reactions.

Delaunay, Jean-Jacques; Yanagisawa, Kazumasa; Nishino, Toshiki; Yamada, Ichiro

2007-03-01

245

An Industrial Streamer Corona Plasma System for Gas Cleaning  

Microsoft Academic Search

For pulsed corona plasma applications, it becomes important to develop pilot systems with large average power and high-energy conversion efficiency. Since the beginning of 2000, we have been working on an industrial corona plasma system with tasks of 10-30 kW in average power and higher than 90% of total energy conversion efficiency. The pulsed-power source should have the following specifications:

G. J. J. Winands; Keping Yan; A. J. M. Pemen; S. A. Nair; Zhen Liu; E. J. M. van Heesch

2006-01-01

246

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

247

[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

248

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

249

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

250

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

NASA Astrophysics Data System (ADS)

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.

Le, H. C.; Zeitoun, D. E.; Parisse, J. D.; Sentis, M.; Marine, W.

2000-09-01

251

Ethylene Oxide for Soil Sterilization  

Microsoft Academic Search

ETHYLENE oxide has been used for soil sterilization by introducing it under reduced pressure to containers holding the soil in pots or trays. Results have been satisfactory so far as sterilization is concerned, and there appears to be a minimum change in chemical and physical properties of the soil, though certain changes have been reported1.

R. E. Rose; R. W. Bailey

1952-01-01

252

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Interaction of laser radiation with a dense gas target  

NASA Astrophysics Data System (ADS)

An investigation was made of the interaction of a nanosecond laser pulse with a 'puff' gas target at gas densities sufficient for the formation of a critical-density plasma. The parameters of the laser plasma formed in the central interaction region and at its periphery were determined by x-ray spectroscopic methods. The formation of a plasma channel was observed and it was attributed to self-focusing of the laser radiation in the ionised gas.

Bartnik, A.; Dyakin, V. M.; Skobelev, I. Yu; Faenov, A. Ya; Fiedorowicz, H.; Szczurek, M.

1997-01-01

253

Plasma density evolution during nanosecond discharge in hydrogen gas at (1–3) × 105 Pa pressure  

NASA Astrophysics Data System (ADS)

The results of a study of the nanosecond discharge in H2 gas at pressures of (1–3) × 105 Pa using fast-framing photography and space- and time-resolved spectroscopy are presented. The discharge is initiated by the application of a high-voltage pulse with an amplitude of ?100 kV and duration of ?5 ns to a blade cathode placed at a distance of 20 mm from the anode. The results show the dynamics of the discharge formation and the build-up of the plasma electron density in the discharge channels close to and at a distance from the edge of the cathode. The results obtained are compared to those obtained in recent studies of similar discharges in air and He gas. It was shown that the time and space evolution of the plasma light emission in the H2 gas discharge is very similar to that in air. Namely, the generation of the plasma is mainly confined to the plasma channels initiated at the top and bottom edges of the cathode electrode and that there are no new plasma channels formed from the explosive emission centres along the blade as it was obtained in earlier experiments with He gas. Spectroscopic measurements showed that the plasma density reaches 2 × 1017 cm?3 and 1.6 × 1016 cm?3 in the vicinity of the cathode and the middle of the anode–cathode gap, respectively, for a plasma electron temperature of <1.5 eV. The values of plasma electron density and the previously presented results of electric field measurements allow calculation of the resistance of the plasma channels.

Yatom, S.; Krasik, Ya E.

2014-05-01

254

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

255

Electrolytic silver ion cell sterilizes water supply  

NASA Technical Reports Server (NTRS)

Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

Albright, C. F.; Gillerman, J. B.

1968-01-01

256

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

257

Gas temperature determination from rotational lines in non-equilibrium plasmas: a review  

NASA Astrophysics Data System (ADS)

The gas temperature in non-equilibrium plasmas is often obtained from the plasma-induced emission by measuring the rotational temperature of a diatomic molecule in its excited state. This is motivated by both tradition and the availability of low budget spectrometers. However, non-thermal plasmas do not automatically guarantee that the rotational distribution in the monitored vibrational level of the diatomic molecule is in equilibrium with the translational (gas) temperature. Often non-Boltzmann rotational molecular spectra are found in non-equilibrium plasmas. The deduction of a gas temperature from these non-thermal distributions must be done with care as clearly the equilibrium between translational and rotational degrees of freedom cannot be achieved. In this contribution different methods and approaches to determine the gas temperature are evaluated and discussed. A detailed analysis of the gas temperature determination from rotational spectra is performed. The physical and chemical background of non-equilibrium rotational population distributions in molecular spectra is discussed and a large range of conditions for which non-equilibrium occurs are identified. Fitting procedures which are used to fit (non-equilibrium) rotational distributions are analyzed in detail. Lastly, recommendations concerning the conditions for which the gas temperatures can be obtained from diatomic spectra are formulated.

Bruggeman, P. J.; Sadeghi, N.; Schram, D. C.; Linss, V.

2014-04-01

258

Conditional sterility in plants  

DOEpatents

The present disclosure provides methods, recombinant DNA molecules, recombinant host cells containing the DNA molecules, and transgenic plant cells, plant tissue and plants which contain and express at least one antisense or interference RNA specific for a thiamine biosynthetic coding sequence or a thiamine binding protein or a thiamine-degrading protein, wherein the RNA or thiamine binding protein is expressed under the regulatory control of a transcription regulatory sequence which directs expression in male and/or female reproductive tissue. These transgenic plants are conditionally sterile; i.e., they are fertile only in the presence of exogenous thiamine. Such plants are especially appropriate for use in the seed industry or in the environment, for example, for use in revegetation of contaminated soils or phytoremediation, especially when those transgenic plants also contain and express one or more chimeric genes which confer resistance to contaminants.

Meagher, Richard B. (Athens, GA); McKinney, Elizabeth (Athens, GA); Kim, Tehryung (Taejeon, KR)

2010-02-23

259

Mechanisms of gas precipitation in plasma-exposed tungsten  

NASA Astrophysics Data System (ADS)

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).

Kolasinski, R. D.; Cowgill, D. F.; Donovan, D. C.; Shimada, M.; Wampler, W. R.

2013-07-01

260

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

261

Impact of gas heating on an rf-plasma structure in a microcell at high pressure  

NASA Astrophysics Data System (ADS)

In a micro-plasma confined in a small volume at atmospheric pressure, we may have to consider the influence of the local heating of feed gases on the inner plasma parameters, plasma production rate etc. A capacitively coupled micro-plasma in an axisymmetric two dimensional space is theoretically investigated in Ar driven at 13.56 MHz as a typical example. The governing equation of temperature in a gas phase and on a wall is joined with conventional system equations of electrons, ions and long-lived metastable molecules as well as the potential based on the relaxation continuum (rct) model. We first stress in the micro-plasma at atmospheric pressure that an electron with intermediate energy plays an important role in plasma production through stepwise ionization in the presence of high-density metastable having a low ionization threshold. A new sustaining mechanism in the rf-CCP will be demonstrated. That is, the rf micro-plasma is sustained in the instantaneous anode-phase of the powered electrode. Secondly we bring up the enhancement of the net ionization rate by high energy electrons through the increase of the local reduced field, E(r,t)/N(r), under the appearance of a broad minimum of the number density of the heated neutral gas. In the later part of the talk, we will discuss the historically development of the basic concept, reduced-field, employed in the field of collisional low temperature plasmas.

Makabe, Toshiaki

2012-10-01

262

Gold-carbon composite thin films for electrochemical gas sensor prepared by reactive plasma sputtering  

NASA Astrophysics Data System (ADS)

We have investigated the properties of gold-carbon composite thin films prepared by a plasma sputtering deposition using argon and methane mixture gas. These composite films have an uneven surface in submicron scale or consist of nano-scale particles of gold polycrystalline. Such morphological properties can be controlled by the sputtering voltage and the partial pressure of methane gas. The working electrode of electrochemical gas sensor has needed a stable gas sensitivity and a good gas selectivity. Our composite film is one of the excellent candidates for a thin film working electrode of electrochemical gas sensor. It is described that the output current of sensor is related to the preparation conditions of the thin films and increase linearly as the concentration of PH 3 gas ranging from 0.1 to 1.0 ppm is increasing.

Okamoto, A.; Suzuki, Y.; Yoshitake, M.; Ogawa, S.; Nakano, N.

1997-01-01

263

Measurement of the plasma and neutral gas flow velocities in a low-pressure hollow-cathode plasma jet sputtering system  

NASA Astrophysics Data System (ADS)

We present results from two mutually independent measurements of plasma and neutral gas flow velocities in a plasma jet deposition system. Operation of a hollow-cathode discharge within the plasma jet nozzle in the pulse regime enables the simple use of a classical Langmuir probe for the plasma flow velocity measurement. In this method, we assume that the plasma is generated solely inside the nozzle during the power impulse and we measure the time of flight of the ions along a known distance between the nozzle end and the probe. The plasma velocity at the plasma jet axis is then determined by differentiation of the dependence of the distance covered by ions on time. As the second method the well-known Pitot tube is used for measurement of the neutral gas velocity. By comparison of both methods we have experimentally proved that the neutral gas flow velocity is almost unaffected by the presence of the plasma, i.e. it does not substantially depend on whether the discharge is switched on or off. The results of both methods correspond well; detected differences are qualitatively explained. It is documented that the plasma jet can be operated both in a subsonic and in a supersonic regime. We present the dependences of the plasma and neutral gas flow velocity on the distance from the cathode, on the pressure in the reactor chamber, and on the flow rate of the working gas.

Kluso?, J.; Kudrna, P.; Tichý, M.

2013-02-01

264

Atomic Force Microscope Investigations of 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 bacteria in biofilm communities, where 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). Cell morphology and biofilm structure were investigated through AFM images obtained for various plasma exposure times. Also, structural properties of the biofilms were studied through force-distance curves by pressing the AFM tip into the film surface while monitoring the cantilever deflection.

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

2010-03-01

265

Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows  

SciTech Connect

The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial magnetic field. In this way, the neutrals are prevented to reach the target region. The neutral flux to the target must be lower than the plasma flux to enable ITER relevant plasma-surface interaction (PSI) studies. It is therefore essential to control the neutral gas dynamics. The DSMC method was used to model the expansion of a hot gas in a low pressure vessel where a small discrepancy in shock position was found between the simulations and a well-established empirical formula. Two stage differential pumping was modeled and applied in the linear plasma devices Pilot-PSI and PLEXIS. In Pilot-PSI a factor of 4.5 pressure reduction for H{sub 2} has been demonstrated. Both simulations and experiments showed that the optimum skimmer position depends on the position of the shock and therefore shifts for different gas parameters. The shape of the skimmer has to be designed such that it has a minimum impact on the shock structure. A too large angle between the skimmer and the forward direction of the gas flow leads to an influence on the expansion structure. A pressure increase in front of the skimmer is formed and the flow of the plasma beam becomes obstructed. It has been shown that a skimmer with an angle around 53 deg. gives the best performance. The use of skimmers is implemented in the design of the large linear plasma generator Magnum-PSI. Here, a three stage differentially pumped vacuum system is used to reach low enough neutral pressures near the target, opening a door to PSI research in the ITER relevant regime.

Eck, H. J. N. van; Koppers, W. R.; Rooij, G. J. van; Goedheer, W. J.; Cardozo, N. J. Lopes; Kleyn, A. W. [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Engeln, R.; Schram, D. C. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2009-03-15

266

Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows  

NASA Astrophysics Data System (ADS)

The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial magnetic field. In this way, the neutrals are prevented to reach the target region. The neutral flux to the target must be lower than the plasma flux to enable ITER relevant plasma-surface interaction (PSI) studies. It is therefore essential to control the neutral gas dynamics. The DSMC method was used to model the expansion of a hot gas in a low pressure vessel where a small discrepancy in shock position was found between the simulations and a well-established empirical formula. Two stage differential pumping was modeled and applied in the linear plasma devices Pilot-PSI and PLEXIS. In Pilot-PSI a factor of 4.5 pressure reduction for H2 has been demonstrated. Both simulations and experiments showed that the optimum skimmer position depends on the position of the shock and therefore shifts for different gas parameters. The shape of the skimmer has to be designed such that it has a minimum impact on the shock structure. A too large angle between the skimmer and the forward direction of the gas flow leads to an influence on the expansion structure. A pressure increase in front of the skimmer is formed and the flow of the plasma beam becomes obstructed. It has been shown that a skimmer with an angle around 53° gives the best performance. The use of skimmers is implemented in the design of the large linear plasma generator Magnum-PSI. Here, a three stage differentially pumped vacuum system is used to reach low enough neutral pressures near the target, opening a door to PSI research in the ITER relevant regime.

van Eck, H. J. N.; Koppers, W. R.; van Rooij, G. J.; Goedheer, W. J.; Engeln, R.; Schram, D. C.; Cardozo, N. J. Lopes; Kleyn, A. W.

2009-03-01

267

Vacuum arc plasma jet interaction with neutral ambient gas  

Microsoft Academic Search

Vacuum arc plasma jet (VAPJ) propagation in a neutral nitrogen atmosphere has been calculated numerically on the basis of a hydrodynamic description. It was assumed that the VAPJ was emitted isotropically from a point source located z0 = 20 mm in front of the entrance of a straight duct 100 mm in diameter in which an axial magnetic field of

E. Gidalevich; S. Goldsmith; R. L. Boxman

2000-01-01

268

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

269

Determination of isosorbide-5-mononitrate in human plasma by high-resolution gas chromatography  

Microsoft Academic Search

A method for the determination of isosorbide-5-mononitrate (5-ISMN) in human plasma by capillary gas chromatography with electron-capture detection was developed and applied to clinical samples. 9-Fluorenone was used as an internal standard, ethyl acetate was employed for liquid–liquid extraction. The advantage of the extraction procedure is the possibility of a direct injection of the plasma extract, without solvent removal\\/reconstitution of

J Pastera; L Vysloužil; J Kv?tina

2004-01-01

270

The relationship between gas-phase processes and the structure of polyaniline obtained by plasma polymerization  

Microsoft Academic Search

The composition of the gas phase during plasma polymerization of aniline was studied with the use of mass spectrometry; it\\u000a was shown that at least 20% of aniline is consumed for the formation of secondary products (C2H2 and HCN). According to solid-state NMR data, the macromolecular chain of polyaniline obtained by plasma polymerization includes\\u000a both aniline and aliphatic units. The

E. N. Demidova; V. M. Matyuk; A. I. Drachev; A. B. Gil’man; E. B. Pomakhina

2009-01-01

271

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

272

Amplification of Short Laser Pulses by Resonant Raman Scheme in a Gas Jet Plasma  

NASA Astrophysics Data System (ADS)

Raman amplification of subpicosecond laser pulses up to ¡­ 60 times is demonstrated in a gas jet plasma. The achievement of this large amplification is likely due to achieving a uniformity of plasma density greater than in previous studies. Interestingly, as the amplification increases, so does the spectral bandwidth of the amplified pulse. An indirect measurement of the amplified pulse duration shows larger amplification occurring for output pulses of shorter duration. This work was supported by DARPA and NSF (PHYS) grants.

Ping, Yuan; Cheng, Weifeng; Suckewer, Szymon; Clark, Daniel; Fisch, Nathaniel

2003-10-01

273

Non-thermal atmospheric gas plasma device for surface decontamination of shell eggs  

Microsoft Academic Search

A resistive barrier discharge (RBD) prototype able to generate gas plasma at atmospheric conditions was set up. The discharge was electrically characterized and the plasma glow was analysed by optical emission spectroscopy. The decontamination power of the device was assessed on samples of shell eggs experimentally inoculated with Salmonella Enteritidis and Salmonella Typhimurium (5.5–6.5 Log CFU\\/eggshell) and placed in the

Luigi Ragni; Annachiara Berardinelli; Lucia Vannini; Chiara Montanari; Federico Sirri; Maria Elisabetta Guerzoni; Adriano Guarnieri

2010-01-01

274

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

275

GAS CHROMATOGRAPHIC ASSAY FOR ESTAZOLAM IN HUMAN PLASMA AND RESULTS OF A BIOEQUIVALENCE STUDY  

Microsoft Academic Search

This paper describes a new sensitive gas chromatographic method with electron capture detector to assay estazolam in human plasma, which has been developed and validated for pharmacokinetic purposes. The drug and the internal standard (triazolam) were extracted from plasma buffered at pH 9.0 into toluene and analysed on a widebore DB 17 column. The calibration curve covered the 1.0–200ngml?1range with

L DAL BO; F VERGA; A MARZO; P LA COMMARE; M. L DE VITO

1997-01-01

276

Plasma nitrosulfurizing techniques for low friction coefficient with H 2S and C 3H 8 gas addition  

Microsoft Academic Search

AISI 1045 steels were plasma nitrosulfurized with C3H8 gas to enhance surface hardness as well as tribological properties. During the plasma nitrosulfurizing, 100 sccm of C3H8 gas was added to the mixture of N2, H2 and H2S. The process was carried out under 2 torr pressure at 550 °C for 2 h. When C3H8 gas was added to the gas mixture, surface hardness was

Y. K. Ko; S. Yoo; K. I. Moon; W. B. Lee; S. W. Kim; Y. Z. You

2008-01-01

277

Gas flow dependence for plasma-needle disinfection of S. mutans bacteria  

NASA Astrophysics Data System (ADS)

The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then treated with plasma. Afterwards, the sample was incubated and then imaged. These images, which serve as a biological diagnostic for characterizing the plasma, show a distinctive spatial pattern for killing that depends on the gas flow rate. As the flow is increased, the killing pattern varies from a solid circle to a ring. Images of the glow reveal that the spatial distribution of energetic electrons corresponds to the observed killing pattern. This suggests that a bactericidal species is generated in the gas phase by energetic electrons less than a millimetre from the sample surface. Mixing of air into the helium plasma is required to generate the observed O and OH radicals in the flowing plasma. Hydrodynamic processes involved in this mixing are buoyancy, diffusion and turbulence.

Goree, J.; Liu, Bin; Drake, David

2006-08-01

278

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

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

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

281

Development of a laser-induced plasma probe to measure gas phase plasma signals at high pressures and temperatures  

NASA Astrophysics Data System (ADS)

The ability of laser induced breakdown spectroscopy (LIBS) technique for on line simultaneous measurement of elemental concentrations has led to its application in a wide number of processes. The simplicity of the technique allows its application to harsh environments such as present in boilers, furnaces and gasifiers. This paper presents the design of a probe using a custom optic which transforms a round beam into a ring (Donut) beam, which is used for forming a plasma in an atmosphere of nitrogen at high pressure (20 bar) and temperature (200 °C). The LIBS experiments were performed using a high pressure cell to characterize and test the effectiveness of the donut beam transmitted through the LIBS probe and collect plasma signal in back scatter mode. The first tests used the second harmonic of a Nd:YAG laser, pulse width 7 ns, to form a plasma in nitrogen gas at five different pressures (1, 5, 10, 15 and 20 bar) and three different gas temperatures (25, 100 and 200 °C). The uniqueness of this probe is the custom made optic used for reshaping the round laser beam into a ring (Donut) shaped laser beam, which is fed into the probe and focused to form a plasma at the measurement point. The plasma signal is collected and collimated using the laser focusing lens and is reflected from the laser beam axis onto an achromatic lens by a high reflection mirror mounted in the center section of the donut laser beam. The effect of gas pressure and temperature on N(I) lines in the high pressure cell experiment shows that the line intensity decreases with pressure and increases with temperature. Mean plasma temperature was calculated using the ratios of N(I) line intensities ranging from 7400 K to 8900 K at 1 bar and 2400 K to 3200 K at 20 bar for the three different gas temperatures. The results show that as a proof of principle the donut beam optics in combination with the LIBS probe can be used for performing extensive LIBS measurements in well controlled laboratory environment as well as harsh and demanding environments of practical devices at both high pressures and temperatures.

Gounder, J. D.; Kutne, P.; Meier, W.

2012-08-01

282

[Sterilization: necessity or genocide?].  

PubMed

Recent warnings by the UN Fund for Population Activities about the rapid growth of the world population and the overwhelming role in it played by impoverished women in developing countries are of interest to all women in Latin America. According to the document, Third World Women require drastic improvements in their socioeconomic positions in order to achieve reductions in their family sizes and avoid an increase in the world population from 5 billion at present to 10 billion in 2025, which would be a disaster for the planet. The document states that much of the environmental damage that would occur would be attributable to the combination of poverty and rapid population increase. If the proportion of the world's women using contraceptives increases from the current 45% to 58% by the year 2000, the world population in 2025 will be 8.5 billion. The document recommends that the amount of money invested in family planning be greatly increased by 2000 in order to make possible increased use of family planning. It appears, however, that much of the funding for family planning is under the control of private organizations and is used to serve the interests of foreign countries. The 2 principal private family planning organizations in Brazil, for example, received 18.2 million US dollars between 1978--84, which were used largely to finance a campaign of mass sterilization. Brazil's rate of population growth, which was 2.1% in 1980-85 and 1.8% in 1990, is expected to drop to 1.6% in 1995. With the decline in the rate of growth, the population will be 170 million in 2000 instead of the 220 million projected using data from the 1970s. A much higher proportion of fertile-aged women in Brazil is sterilized than in the US or Europe . Closer examination of the premises behind family planning policies shows them to be questionable. The premise that population density affects the environment is questionable; Japan, West Germany, and Holland have some of the highest population densities in the world but are highly developed. On the other hand Bolivia and Peru are underdeveloped but have very low population densities. Brazil has 1 of the lowest population densities in the world at 14 inhabitants per sq km. Rural- urban migration in the past few decades has transferred a hugh contingent of rural dwellers to the outskirts of the large and medium sized cities. Brazil's perverse economic model that concentrates income, focuses on exports, and encourages latifundia, and not population density, is responsible for urban growth. A truly efficient demographic policy would seek a transformation of the economic model. Another myth is that environmental damage is caused by poverty and rapid population growth. The most polluting countries of the world are the most developed and richest. Population movements in Latin American countries with mass sterilization programs should divert the funds to programs improving the status of women, who could then control their own fertility. PMID:12284252

Muraro, R M

1991-01-01

283

Wear behavior of gas tunnel type plasma sprayed Zr-based metallic glass composite coatings  

NASA Astrophysics Data System (ADS)

Gas tunnel type plasma spraying is a prospective method to produce metallic glass composite coatings with high quality due to its noteworthy feature of process controllability. In this study, Zr55Cu30Al10Ni5 metallic glass composite coatings were produced by gas tunnel type plasma spraying torch under optimum spraying conditions with selected plasma currents. The formation mechanism, sliding, and erosive wear behaviors of the coatings with respect to plasma current was examined. The phase and thermal analyses as well as microstructure of the plasma sprayed coatings produced at different plasma currents were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The sliding and erosive wear behaviors of the coatings were studied using a pin-on-disc and a specially designed erosive wear tester, respectively. The results showed that an increase in plasma current increased the crystalline content in the metallic glass composite coatings, which enhanced the hardness and wear resistance of the coatings.

Yugeswaran, S.; Kobayashi, A.; Suresh, K.; Rao, K. P.; Subramanian, B.

2012-09-01

284

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

NASA Astrophysics Data System (ADS)

In laboratory experiments, I study strongly-coupled dusty plasma levitated in a glow-discharge plasma. Dusty plasma is an arrangement of small dust particles in a plasma background of electrons, ions, and neutral gas. The dust particles are negatively charged because they collect electrons and ions from the background plasma. Depending on the experimental setup, the plasma's electric field can help to balance the dust particles against gravity. The high dust charge causes dust particles to repel each other, while confinement forces prevent their escape. The dust particles cannot easily move past one another, and instead organize themselves into highly-ordered structures. The neutral gas also plays a key role in these experiments. Depending on the relative motion between gas and dust particles, the neutral gas can either impede dust motion or it can drive the dust into motion. In this thesis, I report the findings of three separate experiments. In the first experiment, I use a spherically-shaped dusty plasma (Yukawa ball) as an indicator of a flow of neutral gas, called thermal creep flow. In the second and third experiments, I study naturally occurring dust-density waves, which propagate within the volume of a dusty plasma that has many horizontal layers. In Ch. 2 of this thesis, I study thermal creep flow (TCF), which is a flow of gas driven by a temperature gradient along a solid boundary. Stripes on a glass box are heated by laser beam absorption, leading to both TCF and a thermophoretic force. A stirring motion of the dust particle suspension is observed. By eliminating all other explanations for this motion, I 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 that TCF in the slip-flow regime causes steady-state gas flow in a confined volume. In Ch. 3, I observe the growth of a naturally occurring dust-density wave (DDW) using high-speed imaging. This low-frequency wave (˜ 25 Hz) grows in amplitude as it propagates downward through a dusty plasma. I measure the wave's linear growth rate using a phase-sensitive analysis method. For the conditions studied here, the growth rate increases as gas pressure decreases. At a critical gas pressure that I observe, a balance between an ion-flow instability and dissipation by neutral gas drag determines a threshold for wave propagation. A linear dispersion relation is derived, taking into account effects of strong coupling, to compare to the experiment. In Ch. 4, I observe the development of nonlinearity in the naturally occurring dust-density wave by measuring harmonics of the fundamental. Using high-speed imaging, I measure amplitudes, wave numbers and growth rates for the fundamental and its harmonics. The amplitudes of the harmonics exhibit a strong exponential increase with diminishing gas pressure, and they saturate at lower gas pressures. My measurements show that the wave numbers and growth rates of harmonics are near integer multiples of the fundamental.

Flanagan, Timothy Mcguire

285

Features of plasma glow in low pressure terahertz gas discharge  

SciTech Connect

Investigations of the low pressure (1–100 Torr) gas discharge in the powerful (1 kW) quasi-optical terahertz (0.55 THz) wave beams were made. An intense afterglow was observed after the end of gyrotron terahertz radiation pulse. Afterglow duration significantly exceeded radiation pulse length (8 ?s). This phenomenon could be explained by the strong dependence of the collisional-radiative recombination rate (that is supposed to be the most likely mechanism of electron losses from the low pressure terahertz gas discharge) on electron temperature.

Bratman, V. L.; Golubev, S. V.; Izotov, I. V.; Kalynov, Yu. K.; Koldanov, V. A.; Razin, S. V. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation)] [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Litvak, A. G.; Sidorov, A. V.; Skalyga, V. A.; Zorin, V. G. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation) [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina st., 603950 Nizhny Novgorod (Russian Federation)

2013-12-15

286

The effect of different plasma gas environments on vermiculite layer  

Microsoft Academic Search

This work presents the first results of a broader research project aimed at the development or modifications of clays with increased properties for technological purposes and novel applications. This first step addresses on the chemical and physical properties of vermiculite treated with several ionised gasses in controlled plasma environments. Vermiculite is a 2:1 layered silicate with well-known chemical-exchange and surface

Giovanni Valdrè; Daniele Malferrari; Diego Marchetti; Maria Franca Brigatti

2007-01-01

287

Inductively coupled plasma reactive ion etching of titanium thin films using a Cl 2\\/Ar gas  

Microsoft Academic Search

Inductively coupled plasma reactive ion etching of titanium thin films patterned with a photoresist using Cl2\\/Ar gas was examined. The etch rates of the titanium thin films increased with increasing the Cl2 concentration but the etch profiles varied. In addition, the effects of the coil rf power, dc-bias voltage and gas pressure on the etch rate and etch profile were

Yu Bin Xiao; Eun Ho Kim; Seon Mi Kong; Jae Hyun Park; Byoung Chul Min; Chee Won Chung

2010-01-01

288

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

Microsoft Academic Search

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

Yukinori Sakiyama; Nikolas Knake; Daniel Schröder; Jörg Winter; Volker Schulz-von der Gathen; David B. Graves

2010-01-01

289

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

290

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

NASA Astrophysics Data System (ADS)

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 work we are trying to expand and apply existing models to the helium gas propellant case. Though the specific impulse is somewhat lower with heavier helium atoms, but unlike hydrogenic species helium doesn't form molecules, and therefore shows less radiative losses. We extend 0-D plasma-chemistry, 1-D mixed-collisional and kinetic gas flow models [11] to characterize gas/plasma composition and condition in the helium helicon discharge. Recent experiments suggest that there is a strong dependence of both VASIMR 1st and 2nd stage performance on the magnetic field mirror ratio in the VX-10 experimental configuration. We study effects of the plasma particles trapping in a strong magnetic field and their acceleration by the combination of the mirror force and ambipolar potential for the typical VASIMR experiment conditions. We also discuss possibility for plasma instabilities and comment on the micro-scale plasma transport in the VASIMR thruster. [1] Chang Díaz F.R., "Research Status of The Variable Specific Impulse Magnetoplasma Rocket", Proc. 39th Annual Meeting of the Division of Plasma Physics (Pittsburgh, PA, 1997), Bulletin of APS, 42 (1997) 2057. [2] Chang Díaz, F. R., Squire, J. P., Carter, M., et al., `'Recent Progress on the VASIMR'', Proc. 41th Annual Meeting of the Division of Plasma Physics (Seattle, WA, 1999), Bulletin of APS, 44 (1999) 99. [3] Chang Díaz, F. R., Squire, J. P., Ilin, A. V., et al. "The Development of the VASIMR Engine", Proceedings of International Conference on Electromagnetics in Advanced Applications (ICEAA99), Sept. 13-17, 1999, Torino, Italy, (1999) 99-102. [4] F.R.Chang Diaz et al., "An Overview of Current Research on the VASIMR Engine", DPP-2000, Bull. APS, vol.45, 7 (2000) 129. [5] J.P.Squire, "Recent Experimental Results in the VX-10 Device", DPP-2000, Bull. APS, vol.45, 7 (2000) 130. [6] O.Batishchev and K.Molvig, "Kinetic Simulation of the high Isp Plasma Thruster", JPC-36, AIAA-3754 technical paper, Huntsville (2000) 11p. [7] O.Batishchev and K.Molvig, "Study of the Operational Regimes of the VASIMR Helicon Plasma Source", DPP- 2000, Quebec City, Canada, Bull. APS, 45, 7 (2000) 130. [8] O.Batishchev and K.Molvig, "Study of Mixed Collisionality Gas Flow in the VASIMR Thruster", DFD-2000, DC, USA, Bull. APS, 45, 9 (2000) 169. [9] O.Batishchev and K.Molvig, "Kinetic Model of a Helicon Plasma Source for VASIMR", ACME-39, AIAA-0963 technical paper, ASME-39, Reno, 2001. [10] O.Batishchev and K.Molvig "Kinetic study of the VASIMR thruster operational regimes", JPC-37, AIAA-3501 technical paper, Salt-Lake City, 2001. [11] O.Batishchev and K.Molvig, "Numerical study of plasma production in the VASIMR thruster", IEPC-01-208 paper, 27 Int. Electric Prop. Conf., Pasadena CA, 15-19 October, -19p, 2001.

Batishchev, O.; Molvig, K.

2002-01-01

291

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

292

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

293

Radiation sterilization of hydrocortisone acetate.  

National Technical Information Service (NTIS)

The feasibility of using high energy ionizing radiation for the sterilization of hydrocortisone acetate was investigated. Hydrocortisone acetate in the form of powder was exposed to different dose levels of gamma radiation using a Cobalt-60 source. The ir...

A. Charef A. Boussaha

1989-01-01

294

Sterilization surgery - making a decision  

MedlinePLUS

Sterilization surgery in women is called tubal ligation . In men, it is called a vasectomy . Often, people in a long-term, monogamous (same person) relationship who have already had several children ...

295

Magnetically insulated ion diode with a gas-breakdown plasma anode  

NASA Astrophysics Data System (ADS)

An active anode plasma source was operated on the LONGSHOT annular magnetically insulated ion diode. This source uses an inductive voltage from a single turn coil to break down an annular gas puff produced by a supersonic nozzle. The resulting plasma is magnetically driven toward the radial insulating magnetic field in the diode accelerating gap and stagnates as a well-defined surface after about 300 ns to form a plasma anode layer defined by magnetic fields. An ion beam is then extracted from this plasma layer by applying typically a 150 kV, 1 microsecond pulse to the accelerating gap. Optimization of the timing of the gas puff, the plasma production discharge and the high voltage pulse has resulted in 1 microsecond duration 75 to 150 keV ion beam pulses with greater than 100 A/sq cm peak ion current density over an area of about 400 sq cm. Up to 5 J/sq cm was collected by a 4 sq cm calimeter. The diode impedance history can be varied so that rising, flat, and falling voltage pulse waveforms can be produced. Streak photographs of beamlets impinging on a scintillator and time integrated targets both show beam divergence angles equal to or less than 3 degrees, but under certain operating conditions, large excursions in mean aiming angle on time scales of 20 to 200 ns. These and other operating characteristics of the gas-breakdown diode are discussed.

Greenly, J. B.; Ueda, Mario; Rondeau, G. D.; Hammer, D. A.

1987-09-01

296

Experimental study of the effect of gas nature on plasma arc cutting of mild steel  

NASA Astrophysics Data System (ADS)

This paper is devoted to the experimental investigation of arc cutting of mild steel using plasmas generated in gas and liquid media. Due to different chemical compositions, the examined media have different thermophysical properties, which affect the properties of the generated plasma and cutting performance. The experiments are performed on 15 mm mild steel plates using commercial equipment at 60 A to approach real operation conditions in application areas. The studied gases are chosen according to recommendations of the world's leading manufacturers of arc cutting equipment for mild steel. Specific differences between plasma gases are discussed from the point of view of properties of the gas and the generated plasma, amount of removed material, kerf shape and overall energy balance of the cutting process. The paper describes the role of exothermic reaction of iron oxidation for oxygen cutting and explains its neglect for liquid cutting. This paper explains the potential of facilitating the cutting process by modification of the plasma gas chemical composition and flow rate.

Kavka, T.; Mašláni, A.; Hrabovský, M.; K?enek, P.; Stehrer, T.; Pauser, H.

2013-06-01

297

Thermal plasma-sprayed nickel catalysts in the clean-up of biomass gasification gas  

Microsoft Academic Search

Plasma spraying is a potential catalyst preparation method for hot gas clean-up which requires very durable catalytic coatings. In this work, the multi-layer composite coating powders consisted of a gibbsite or boehmite core together with a hydrotalcite coating. We used the coating powders in the preparation of the powder form Ni catalysts, which were characterized by XRD, BET, XPS, and

Hanne Rönkkönen; Kristina Klemkait?; Alexander Khinsky; Ar?nas Baltušnikas; Pekka Simell; Matti Reinikainen; Outi Krause; Marita Niemelä

2011-01-01

298

Gas plasmas treatment of cathodes to improve Li/So2 cell performance  

NASA Astrophysics Data System (ADS)

Overall performance after storage at 71 C of spirally wound, hermetically sealed, Li/SO2 squat 'D' sized cells discharged at 3 A at -29 C can be improved by exposing the porous carbon cathodes to a room temperature, low pressure gas plasma prior to cell assembly.

Bibder, Michael; Mammone, Robert J.; Thurston, Edward P.; Reddy, Thomas B.

1993-12-01

299

Improvement of NOx Reduction Efficiency in Diesel Emission Using Nonthermal Plasma - Exhaust Gas Recirculation Combined Aftertreatment  

Microsoft Academic Search

Atmospheric-pressure nonequilibrium nonthermal plasma (NTP) hybrid exhaust gas aftertreatment systems have been developed by the authors without using precious metal catalysts and harmful ammonia, etc. Two types of new environmental protection systems (a dry system and a wet system), which enable to produce ultra low CO2, PM (Particulate Matter), NOx emissions, fuel consumption and low cost, are investigated for diesel

Masaaki OKUBO; Takuya KUWAHARA; Yohei KANNAKA; Tomoyuki KUROKI; Keiichiro YOSHIDA

2010-01-01

300

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

301

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

302

Inactivation of Escherichia coli Using the Atmospheric Pressure Plasma Jet of Ar gas  

NASA Astrophysics Data System (ADS)

Germicidal treatments of Escherichia coli on Langmuir--Blodget (LB) agar were performed using the atmospheric pressure plasma jet sources of Ar gas in the ambient air. Shorter distances from the nozzle of the plasma jet device were more effective in achieving higher bactericidal effects on E. coli grown on LB agar. The surface temperature of the agar was monitored and the spectroscopic analysis of the plasma jet was performed in order to evaluate the factors contributing to the bactericidal effect, such as heating, UV emission, and radical formation caused by the plasma jet. Although the plasma jet raised the surface temperature of LB agar up to about 40 °C, the bactericidal effect was not observed. Moreover, the bactericidal effect of UV (200--300 nm) emitted from the plasma jet was negligible compared with the effects of ions and radical species generated by the atmospheric plasma. The results suggest that the ions and radical species generated by the atmospheric pressure plasma jet are critical for high bactericidal effects on E. coli.

Homma, Takeshi; Furuta, Masakazu; Takemura, Yuichiro

2013-03-01

303

A parallel hybrid numerical algorithm for simulating gas flow and gas discharge of an atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

Development of a hybrid numerical algorithm which couples weakly with the gas flow model (GFM) and the plasma fluid model (PFM) for simulating an atmospheric-pressure plasma jet (APPJ) and its acceleration by two approaches is presented. The weak coupling between gas flow and discharge is introduced by transferring between the results obtained from the steady-state solution of the GFM and cycle-averaged solution of the PFM respectively. Approaches of reducing the overall runtime include parallel computing of the GFM and the PFM solvers, and employing a temporal multi-scale method (TMSM) for PFM. Parallel computing of both solvers is realized using the domain decomposition method with the message passing interface (MPI) on distributed-memory machines. The TMSM considers only chemical reactions by ignoring the transport terms when integrating temporally the continuity equations of heavy species at each time step, and then the transport terms are restored only at an interval of time marching steps. The total reduction of runtime is 47% by applying the TMSM to the APPJ example presented in this study. Application of the proposed hybrid algorithm is demonstrated by simulating a parallel-plate helium APPJ impinging onto a substrate, which the cycle-averaged properties of the 200th cycle are presented. The distribution patterns of species densities are strongly correlated by the background gas flow pattern, which shows that consideration of gas flow in APPJ simulations is critical.

Lin, K.-M.; Hu, M.-H.; Hung, C.-T.; Wu, J.-S.; Hwang, F.-N.; Chen, Y.-S.; Cheng, G.

2012-12-01

304

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

305

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

306

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

PubMed

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

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

2002-01-15

307

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

PubMed

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

Kage, Shigetoshi; Kudo, Keiko; Ikeda, Noriaki

2002-09-01

308

Recent nuclear pumped laser results. [gas mixtures and laser plasmas  

NASA Technical Reports Server (NTRS)

Recent direct nuclear pumped laser research has concentrated on experiments with three gas mixtures (Ne-N2, He-Ne-O2, and He-Hg). One mixture has been made to lase and gain has been achieved with the other two. All three of these mixtures are discussed with particular attention paid to He-Hg. Of interest is the 6150-angstroms ion transition in Hg(+). The upper state of this transition is formed directly by charge transfer and by Penning ionization.

Miley, G. H.; Wells, W. E.; Akerman, M. A.; Anderson, J. H.

1976-01-01

309

Experimental Evidence of High-Beta Plasma Confinement in an Axially Symmetric Gas Dynamic Trap  

NASA Astrophysics Data System (ADS)

In the axially symmetric magnetic mirror device gas dynamic trap (GDT), on-axis transverse beta (ratio of the transverse plasma pressure to magnetic field pressure) exceeding 0.4 in the fast ion turning points has been first achieved. The plasma has been heated by injection of neutral beams, which at the same time produced anisotropic fast ions. Neither enhanced losses of the plasma nor anomalies in the fast ion scattering and slowing down were observed. This observation confirms predicted magnetohydrodynamic stability of plasma in the axially symmetric mirror devices with average min-B, like the GDT is. The measured beta value is rather close to that expected in different versions of the GDT based 14MeV neutron source for fusion materials testing.

Ivanov, A. A.; Anikeev, A. V.; Bagryansky, P. A.; Deichuli, P. P.; Korepanov, S. A.; Lizunov, A. A.; Maximov, V. V.; Murakhtin, S. V.; Savkin, V. Ya.; den Hartog, D. J.; Fiksel, G.; Noack, K.

2003-03-01

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

X-ray emission of a xenon gas jet plasma diagnosed with Thomson scattering.  

PubMed

We present the results of a benchmark experiment aimed at validating recent calculation techniques for the emission properties of medium and high-Z multicharged ions in hot plasmas. We use space- and time-resolved M-shell x-ray spectroscopy of a laser-produced gas jet xenon plasma as a primary diagnostic of the ionization balance dynamics. We perform measurements of the electron temperature, electron density, and average charge state by recording simultaneous spectra of ion acoustic and electron plasma wave Thomson scattering. A comparison of the experimental x-ray spectra with calculations performed ab initio with a non-local-thermodynamic-equilibrium collisional-radiative model based on the superconfiguration formalism, using the measured plasma parameters, is presented and discussed. PMID:12006034

Chenais-Popovics, C; Malka, V; Gauthier, J-C; Gary, S; Peyrusse, O; Rabec-Le Gloahec, M; Matsushima, I; Bauche-Arnoult, C; Bachelier, A; Bauche, J

2002-04-01

312

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

313

Sterilization technology in the United States space program.  

NASA Technical Reports Server (NTRS)

Review of a number of techniques that have been used to ensure sterilization of spacecraft. An approach based on a mathematical analysis of a planetary quarantine model is described which defines the limits of the probability of occurrence of undesirable events. The use of thermoradiation (a combination of both heat and gamma or X-radiation) to achieve sterilization at low temperatures and rates of radiation is discussed. Also considered is the use of a residual germicide such as paraformaldehyde and melamine formaldehyde on the treated surface to exert a lethal effect on organisms over a period of time. Finally, two techniques still under investigation are described - namely, the use of an ion plasma stream produced by an RF generator to kill and remove microorganisms, and the use of an unfocused carbon dioxide laser beam to sterilize microorganisms.

Hall, L. B.

1973-01-01

314

Characterization and gas temperature measurements of a waveguide-based microwave plasma torch  

NASA Astrophysics Data System (ADS)

Research to characterize a microwave plasma torch was initiated at Penn State University. Microwave power input into the device initiates and sustains plasma in an argon gas jet issuing from a copper nozzle into the ambient atmosphere. Protruding through a rectangular waveguide, the nozzle acts to enhance the local electric field when microwaves are excited in the waveguide. The plasma resembles a small flame, approximately 2--4 cm in length and less than 1 cm in total diameter. The primary research interests which have driven experimental design and characterization of the torch include (1) increasing plasma jet control via improved impedance matching; (2) reducing the erosion of the nozzle tips; and (3) determining the viability of applying the Penn State Microwave Plasma Torch (PSMPT) to the cutting and melting of materials via gas temperature measurements. Literature on the similar microwave torches---particularly, those of the single-electrode plasma (SEP) type---was reviewed. Several design issues were encountered during early testing with the torch. Impedance matching and nozzle erosion presented the most significant obstacles. Poor impedance matching was overcome most effectively with an automatic tuner that could determine a match quickly. Nozzle erosion is not often addressed in the literature on SEPs. However, significant erosion was a limiting factor in early tests with the torch. More recent testing reveals that erosion can be mitigated by addition of a secondary flow of argon around the primary nozzle gas flow. Gas temperature in the plasma was deduced via OH rotational temperature measurements. Molecular nitrogen spectral interference with the OH spectra required fitting both the OH and N2 second positive system in the region of 305--318 nm. The results of this testing indicate an OH rotational temperature---and assumed gas temperature---between 2700--3400 K. These results indicate that the torch should prove useful in cutting and heat-treatment applications for some materials. Recommended areas of future study include examining the plasma for possible filamentation and enhanced spectroscopic diagnostics.

Hammond, Peter J.

315

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

316

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

317

Female sterilization-acceptor characteristics.  

PubMed

This article reports the findings of a study concerning the socioeconomic characteristics of women undergoing sterilization in India. Only 23% of India's 119 million couples use some form of contraception, but of these, 87% rely on male or female sterilization. It is estimated that some 20 million married women of reproductive age have been sterilized. This study examined the cases of 800 women who underwent sterilization at the Department of Obstetrics and Gynecology of the Kamla Nehru Hospital, Shimla from February 1986 to April 1987. In addition to investigating the socioeconomic characteristics of the women, the study also focused on the knowledge and practice of other contraceptive methods, the motivating factors, and the reasons for undergoing sterilization. The study found that 68% of the women were from rural areas and 32% from urban areas. 71% of the women belonged to lower social classes -- only 40% of the women were literate. 98% of the women were Hindus, the remaining 2% belonging to other religious groups. 72.9% of the women were between the ages of 20 and 33 years, the mean age at sterilization being 27.5 years. While 77.3% of the women has 2 or 3 living children, only 2.6% had only 1 living child. 71.2% of the women had both male and female children, and 9.2% had only female children. Concerning the use of contraception, only 22% of the women had practiced contraception prior to the operation. 70% of the women reported being self-motivated, while 26% said that they had been motivated by a family planning worker or hospital staff member. 96.5% of the women reported multiparity and/or socioeconomic reasons for undergoing the procedure, while 3.5% of the sterilizations were performed for therapeutic reasons. PMID:2103927

Kumar, A; Randhawa, I

1990-01-01

318

Genomic networks of hybrid sterility.  

PubMed

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

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

2014-02-01

319

Microwave desorption: a combined sterilizer/aerator for the accelerated elimination of ethylene oxide residues from sterilized supplies  

SciTech Connect

Ethylene oxide gas is widely used in medical and related facilities for low-temperature sterilization of surgical devices. Evidence of its toxicity and, in particular, its mutagenicity and carcinogenicity provide sufficient reasons for caution in its use and for minimizing exposure. Little advancement has been made in the removal of ethylene oxide residuals from plastics into which the gas is heavily absorbed during sterilization, despite the fact that the gas has been used for 20 years or more. This article describes a novel process (PCT Application/GB85/00509) in which microwave irradiation of ethylene oxide-sterilized materials is utilized to enhance the rate at which the gas is desorbed. The experimental apparatus is described, and an explanation of the effect of microwaves on the energy of activation for diffusion is given. Data are presented in support of the authors' claim of a 400% improvement in the efficiency of the new process over conventional aeration procedures. The advantages and economy of an integrated sterilizer/microwave-enhanced desorber are discussed in the context of the implications that arise from the current regulatory debate.

Samuel, A.H.; Matthews, I.P.; Gibson, C.

1988-02-01

320

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Determination of the temperature of a plasma channel formed by a nanosecond laser pulse interacting with a dense gas target  

NASA Astrophysics Data System (ADS)

An x-ray spectroscopic determination was made of the distribution of the plasma electron temperature Te(?) in a channel formed by the interaction of a nanosecond laser pulse with a dense gas target. The distribution Te(?), combined with the plasma channel parameters measured earlier, could be used to develop and check the validity of a theoretical model of the observed effect.

Bartnik, A.; Dyakin, V. M.; Kostecki, J.; Skobelev, I. Yu; Faenov, A. Ya; Fiedorowicz, H.; Szczurek, M.; Jarocki, R.

1997-04-01

321

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

NASA Astrophysics Data System (ADS)

Phase-selective synthesis of copper oxide nanowires is warranted by several applications, yet it remains challenging because of the narrow windows of the suitable temperature and precursor gas composition in thermal processes. Here, we report on the room-temperature synthesis of small-diameter, large-area, uniform, and phase-pure Cu2O nanowires by exposing copper films to a custom-designed low-pressure, thermally non-equilibrium, high-density (typically, the electron number density is in the range of 1011-1013 cm-3) inductively coupled plasmas. The mechanism of the plasma-enabled phase selectivity is proposed. The gas sensors based on the synthesized Cu2O nanowires feature fast response and recovery for the low-temperature (˜140 °C) detection of methane gas in comparison with polycrystalline Cu2O thin film-based gas sensors. Specifically, at a methane concentration of 4%, the response and the recovery times of the Cu2O nanowire-based gas sensors are 125 and 147 s, respectively. The Cu2O nanowire-based gas sensors have a potential for applications in the environmental monitoring, chemical industry, mining industry, and several other emerging areas.

Cheng, Qijin; Yan, Wei; Randeniya, Lakshman; Zhang, Fengyan; Ken Ostrikov, Kostya

2014-03-01

322

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

323

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

NASA Technical Reports Server (NTRS)

An efficient plasma source producing a high-density (approx.10(exp 19/cu m) light gas (e.g. H, D, or He) flowing plasma with a high degree of ionization is a critical component of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept. We are developing an antenna to apply ICRF power near the fundamental ion cyclotron resonance to further accelerate the plasma ions to velocities appropriate for space propulsion applications. The high degree of ionization and a low vacuum background pressure are important to eliminate the problem of radial losses due to charge exchange. We have performed parametric (e.g. gas flow, power (0.5 - 3 kW), magnetic field , frequency (25 and 50 MHz)) studies of a helicon operating with gas (H2 D2, He, N2 and Ar) injected at one end with a high magnetic mirror downstream of the antenna. We have explored operation with a cusp and a mirror field upstream. Plasma flows into a low background vacuum (<10(exp -4) torr) at velocities higher than the ion sound speed. High densities (approx. 10(exp 19/cu m) have been achieved at the location where ICRF will be applied, just downstream of the magnetic mirror.

Squire, J. P.; Chang-Diaz, F. R.; Jacobson, V. T.; Glover, T. W.; Baity, F. W.; Carter, M. D.; Goulding, R. H.; Bengtson, R. D.; Bering, E. A., III

2003-01-01

324

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

325

Low power gas discharge plasma mediated inactivation and removal of biofilms formed on biomaterials  

PubMed Central

The antibacterial activity of gas discharge plasma has been studied for quiet some time. However, high biofilm inactivation activity of plasma was only recently reported. Studies indicate that the etching effect associated with plasmas generated represent an undesired effect, which may cause live bacteria relocation and thus contamination spreading. Meanwhile, the strong etching effects from these high power plasmas may also alter the surface chemistry and affect the biocompatibility of biomaterials. In this study, we examined the efficiency and effectiveness of low power gas discharge plasma for biofilm inactivation and removal. Among the three tested gases, oxygen, nitrogen, and argon, discharge oxygen demonstrated the best anti-biofilm activity because of its excellent ability in killing bacteria in biofilms and mild etching effects. Low power discharge oxygen completely killed and then removed the dead bacteria from attached surface but had negligible effects on the biocompatibility of materials. DNA left on the regenerated surface after removal of biofilms did not have any negative impact on tissue cell growth. On the contrary, dramatically increased growth was found for these cells seeded on regenerated surfaces. These results demonstrate the potential applications of low power discharge oxygen in biofilm treatments of biomaterials and indwelling device decontaminations.

Traba, Christian; Chen, Long; Liang, Jun F.

2013-01-01

326

Formation of high heat resistant coatings by using gas tunnel type plasma spraying.  

PubMed

Zirconia sprayed coatings are widely used as thermal barrier coatings (TBC) for high temperature protection of metallic structures. However, their use in diesel engine combustion chamber components has the long run durability problems, such as the spallation at the interface between the coating and substrate due to the interface oxidation. Although zirconia coatings have been used in many applications, the interface spallation problem is still waiting to be solved under the critical conditions such as high temperature and high corrosion environment. The gas tunnel type plasma spraying developed by the author can make high quality ceramic coatings such as Al2O3 and ZrO2 coating compared to other plasma spraying method. A high hardness ceramic coating such as Al2O3 coating by the gas tunnel type plasma spraying, were investigated in the previous study. The Vickers hardness of the zirconia (ZrO2) coating increased with decreasing spraying distance, and a higher Vickers hardness of about Hv = 1200 could be obtained at a shorter spraying distance of L = 30 mm. ZrO2 coating formed has a high hardness layer at the surface side, which shows the graded functionality of hardness. In this study, ZrO2 composite coatings (TBCs) with Al2O3 were deposited on SS304 substrates by gas tunnel type plasma spraying. The performance such as the mechanical properties, thermal behavior and high temperature oxidation resistance of the functionally graded TBCs was investigated and discussed. The resultant coating samples with different spraying powders and thickness are compared in their corrosion resistance with coating thickness as variables. Corrosion potential was measured and analyzed corresponding to the microstructure of the coatings. Keywords: High Heat Resistant Coatings, Gas Tunnel Type Plasma Spraying, Hardness, PMID:22905586

Kobayashi, A; Ando, Y; Kurokawa, K

2012-06-01

327

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

328

Plasma and wave phenomena induced by neutral gas releases in the solar wind  

NASA Astrophysics Data System (ADS)

We investigate plasma and wave disturbances generated by nitrogen (N2) gas releases from the cooling system of an IR-camera on board the Vega 1 and Vega 2 spacecraft, during their flybys of comet Halley in March 1986. N2 molecules are ionized by solar UV radiation at a rate of ~ 7 · 10-7 s-1 and give rise to a plasma cloud expanding around the spacecraft. Strong disturbances due to the interaction of the solar wind with the N+2 ion cloud are observed with a plasma and wave experiment (APV-V instrument). Three gas releases are accompanied by increases in cold electron density and simultaneous decreases of the spacecraft potential; this study shows that the spacecraft potential can be monitored with a reference sensor mounted on a short boom. The comparison between the model and observations suggests that the gas expands as an exhaust plume, and approximately only 1% of the ions can escape the beam within the first meters. The releases are also associated with significant increases in wave electric field emission (8 Hz 300 kHz); this phenomenon lasts for more than one hour after the end of the release, which is most likely due to the temporary contamination of the spacecraft surface by nitrogen gas. DC electric fields associated with the events are complex but interesting. No magnetic field perturbations are detected, suggesting that no significant diamagnetic effect (i.e. magnetic cavity) is associated with these events.

Laakso, H.; Grard, R.; Janhunen, P.; Trotignon, J.-G.

2002-01-01

329

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

NASA Astrophysics Data System (ADS)

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 ?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.

Zimakov, V. P.; Kuznetsov, V. A.; Kedrov, A. Yu; Solov'ev, N. G.; Shemyakin, A. N.; Yakimov, M. Yu

2009-09-01

330

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

331

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

332

Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air.  

PubMed

In this study, a bipolar nanosecond pulse with 20ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency. PMID:24845733

Wang, Sen; Wang, Wen-Chun; Yang, De-Zheng; Liu, Zhi-Jie; Zhang, Shuai

2014-10-15

333

Radiation sterilization of new drug delivery systems  

PubMed Central

Radiation sterilization has now become a commonly used method for sterilization of several active ingredients in drugs or drug delivery systems containing these substances. In this context, many applications have been performed on the human products that are required to be sterile, as well as on pharmaceutical products prepared to be developed. The new drug delivery systems designed to deliver the medication to the target tissue or organ, such as microspheres, nanospheres, microemulsion, and liposomal systems, have been sterilized by gamma (?) and beta (?) rays, and more recently, by e-beam sterilization. In this review, the sterilization of new drug delivery systems was discussed other than conventional drug delivery systems by ? irradiation.

Abuhanoglu, Gurhan

2014-01-01

334

Temporal evolution of a gas-plasma-dust system - application to Enceladus' plume and cometary jets  

NASA Astrophysics Data System (ADS)

Electron depletion caused by dust absorption is a well-known phenomenon in dust-rich plasma systems. It is usually considered as an indication of high local dust density. While many discussions have focused on steady state cases, little is known about the temporal evolution of a fast-evolving plasma-dust cloud. Inspired by the Cassini Langmuir probe measurements in the plume of Enceladus, we develop a numerical model that follows the temporal evolution of the charge state of a gas-plasma-dust system by considering the production/loss of various components as well as the expansion of the system. Using in situ measurements as constraints, our modeling results can provide diagnostics of an expanding plasma-dust cloud. The model is applied to study the plume of Enceladus and cometary jets. For Enceladus' plume, our preliminary results show that, the plasma electron depletion has already developed in the high dust density environment near the moon surface and the degree of depletion decreases as the cloud expands and propagates outward. The electron depletion measured at large distances thus may not reflect the local dust-plasma properties but could be a result of the temporal evolution. Similar behavior may also happen in cometary jets and can be better resolved by the coming Rosetta mission.

Hsu, S.; Horanyi, M.; Kempf, S.; Ip, W.

2013-12-01

335

Numerical study on the Z pinch dynamics of gas jet type discharge produced plasma (DPP) source  

NASA Astrophysics Data System (ADS)

Z pinch DPP source is often used as an Extreme Ultra-Violet (EUV) source. It is convenient to produce high temperature and high density plasma. There are several analytical models to describe the dynamics of the plasma. The snowplow model is a simple and widely used model to analyze the motion of the plasma shell and predict the pinch time; however, it is incapable of analyzing the plasma behavior after the maximum pinch and providing detailed information of concerned plasma parameters, such as electron density and electron temperature. In this study, we present the simulation results of the Z pinch DPP dynamics obtained by a 2D MHD code. This code solves the problem based on the assumption of single fluid, two temperature approximations in the cylindrical geometry. The numerical scheme for this MHD code is Total-Variation-Diminishing scheme in Lax Friedrich formulation (TVD-LF). The evolution of electron density, electron temperature, current density, magnetic flux and some other important parameters in Z pinch dynamics are investigated with this code. The simulation results show that the maximum pinch electron density is on the order of 10^19 cm-3, with a pinch plasma radius of about 0.1 mm. In order to optimize the radiation output, the influences of initial gas distribution and the current waveform on the Z pinch dynamics are also investigated. They affect the electron density at pinch stagnation obviously; while in term of electron temperature, the effect is slight.

Huang, Bin; Xie, Bin; Tomizuka, Taku; Watanabe, Masato; Xiao, Feng; Hotta, Eiki

2012-10-01

336

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

337

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

338

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

339

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

340

Sterile Neutrinos and Supernova Nucleosynthesis  

NASA Astrophysics Data System (ADS)

Neutrinos play an important role in the core-collapse supernova environment, from facilitating the explosion mechanism to influencing the outflow's elemental composition. Traditional heavy element nucleosynthesis, the r-process, are stifled by electron neutrinos during the alpha particle formation epoch. Introduction of a sterile neutrino species can temper this alpha effect as well as generate an environment sufficiently neutron-rich for fission cycling to occur. Fission cycling in the r-process produces abundance patterns similar to the halo star data. Here we examine reductions in the neutrino flux necessary to achieve fission cycling; sterile neutrinos or other new physics may realize these reductions.

Beun, Joshua; McLaughlin, Gail; Surman, Rebecca; Hix, Raph

2006-10-01

341

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

342

Effect of gas puffing from different side on lower hybrid wave-plasma coupling in experimental advanced superconductive tokamak  

SciTech Connect

Effect of gas puffing from electron-side and ion-side on lower hybrid wave (LHW)-plasma is investigated in experimental advanced superconductive tokamak for the first time. Experimental results with different gas flow rates show that electron density at the grill is higher in the case of gas puffing from electron-side; consequently, a lower reflection coefficient is observed, suggesting better effect of puffing from electron-side on LHW-plasma. The difference in edge density between electron- and ion-side cases suggests that local ionization of puffed gas plays a dominant role in affecting the density at the grill due to different movement direction of ionized electrons and that part of gas has been locally ionized near the gas pipe before diffusing into the grill region. Such difference could be enlarged and important in ITER due to the improvement of plasma parameters and LHW power.

Ding, B. J.; Kong, E. H.; Li, M. H.; Zhang, L.; Wei, W.; Li, Y. C.; Wu, J. H.; Xu, G. S.; Wang, M.; Gong, X. Z.; Shan, J. F.; Liu, F. K. [Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China)] [Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China); Zhang, T. [School of Physics, Hefei University of Technology, Hefei 230009 (China)] [School of Physics, Hefei University of Technology, Hefei 230009 (China); Ekedahl, A. [CEA, IRFM, 13108 St. Paul-lez-Durance (France)] [CEA, IRFM, 13108 St. Paul-lez-Durance (France); Zhao, H. L. [University of Science and Technology of China, Hefei 230026 (China)] [University of Science and Technology of China, Hefei 230026 (China); Collaboration: EAST Team

2013-10-15

343

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

344

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

2010-12-01

345

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

SciTech Connect

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 {mu}F, 50 to 200 nH, and 1 to 3 kV, respectively.

Poehlmann, Flavio R.; Cappelli, Mark A. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Rieker, Gregory B. [Fluence, LLC, 37444 Sycamore Street, Unit 16, Newark, California 94560 (United States)

2010-12-15

346

Computational modelling of discharges within the impulse plasma deposition accelerator with a gas valve  

NASA Astrophysics Data System (ADS)

The paper presents computational studies of working medium dynamics during the impulse plasma deposition (IPD) process when the electric discharge in an interelectrode region is initiated by a gas introduced through a fast-acting valve. During the computational simulations the influence of different discharge parameters on the plasma dynamics was studied. The optimization of the device includes the calculation of the current sheath movement and the sensibility analysis of its dynamics to geometrical and operational parameters. It was found that gas injection can be considered as a useful tool in optimization of the coatings obtained with the IPD technique. Computer simulation results indicate the direction of changes in the development and application of the analysed surface engineering method.

Rabi?ski, Marek; Chodu?, Rafa?; Nowakowska-Langier, Katarzyna; Zdunek, Krzysztof

2014-05-01

347

Effect of He-Ar ratio of side assisting gas on plasma 3D formation during CO2 laser welding  

NASA Astrophysics Data System (ADS)

Side assisting gas plays a very important role in the laser-induced plasma suppression and the gas mixture ratio directly influences the formation and behavior of the laser-induced plasma during the laser welding process. In this paper, a photography system was set up with three synchronous CCD cameras to record the plasma plume during CO2 laser welding under different He-Ar ratios for helium-argon mixed side assisting gas. Three-dimensional reconstruction of the laser-induced plasma based on the computed tomography (CT) technology was achieved from the images shot by the cameras. Four characteristics, including the volume, uniformity, parameter PA associated with plasma absorption and parameter PR associated with laser refraction, were extracted from the 3D plasma and analyzed to investigate the effect on the plasma plume morphology as well as the laser energy attenuation. The results indicated that the He-Ar ratio of the side assisting gas has a considerable influence on some characteristics while some other characteristics are not sensitive to the mixture ratio. In addition, the effect of He-Ar ratio on the laser-induced plasma varies a lot with the flow rate of the side assisting gas.

Sun, Dawei; Cai, Yan; Wang, Yonggui; Wu, Yue; Wu, Yixiong

2014-05-01

348

Charge transfer reactions at interfaces between neutral gas and plasma: Dynamical effects and X-ray emission  

NASA Astrophysics Data System (ADS)

Charge-transfer is the main process linking neutrals and charged particles in the interaction regions of neutral (or partly ionized) gas with a plasma. In this paper we illustrate the importance of charge-transfer with respect to the dynamics and the structure of neutral gas-plasma interfaces. We consider the following phenomena: (1) the heliospheric interface - region where the solar wind plasma interacts with the partly-ionized local interstellar medium (LISM) and (2) neutral interstellar clouds embedded in a hot, tenuous plasma such as the million degree gas that fills the so-called ``Local Bubble". In (1), we discuss several effects in the outer heliosphere caused by charge exchange of interstellar neutral atoms and plasma protons. In (2) we describe the role of charge exchange in the formation of a transition region between the cloud and the surrounding plasma based on a two-component model of the cloud-plasma interaction. In the model the cloud consists of relatively cold and dense atomic hydrogen gas, surrounded by hot, low density, fully ionized plasma. We discuss the structure of the cloud-plasma interface and the effect of charge exchange on the lifetime of interstellar clouds. Charge transfer between neutral atoms and minor ions in the plasma produces X-ray emission. Assuming standard abundances of minor ions in the hot gas surrounding the cold interstellar cloud, we estimate the X-ray emissivity consecutive to the charge transfer reactions. Our model shows that the charge-transfer X-ray emission from the neutral cloud-plasma interface may be comparable to the diffuse thermal X-ray emission from the million degree gas cavity itself.

Provornikova, E.; Izmodenov, V. V.; Lallement, R.

2012-04-01

349

Enantioselective gas chromatographic assay with electron-capture detection for dl-ritalinic acid in plasma.  

PubMed

Enantioselective gas chromatographic assays for the quantitation of methylphenidate and its major metabolite ritalinic acid in plasma are described. The procedures involved the extraction of methylphenidate enantiomers from alkanised plasma. The plasma was then washed to ensure complete removal of methylphenidate before saturation with sodium carbonate to promote the extraction of ritalinic acid enantiomers with ethyl acetate-isopropanol (60:40) solvent mixture. Subsequently, ritalinic acid enantiomers were converted back into methylphenidate enantiomers by Fisher-Speier esterification. N-Heptafluorobutyryl-L-prolyl chloride, a chiral acylating reagent, was used to convert the enantiomers of methylphenidate into their corresponding diastereomeric amide derivatives, which were separated cleanly on an achiral capillary column (OV-225) and quantitated with electron-capture detection. The assays were sensitive, reliable and reproducible. PMID:2079507

Srinivas, N R; Hubbard, J W; Midha, K K

1990-09-14

350

Solidphase extraction of isosorbide dinitrate and two of its metabolites from plasma for gas chromatographic analysis  

Microsoft Academic Search

A rapid, accurate and selective method for the determination of isosorbide dinitrate and its 2- and 5-isosorbide mononitrate metabolites in 1.0 ml of human plasma has been developed. Before chromatographic quantitation by gas-liquid chromatography with electron-capture detection, the compounds are subjected to solid-phase extraction, using ENVI 18 cartridges (Supelco). The intra-day and inter-day coefficients of variation are less than 10%,

I. Gremeau; V. Sautou; V. Pinon; F. Rivault; J. Chopineau

1995-01-01

351

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 by exposure to gas phase or 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. Results of channeling measurements are compared with channeling simulations for hydrogen at lattice locations predicted by density functional theory.

Wampler, W.R.; Barbour, J.C.; Seager, C.H.; Myers, S.M.; Wright, A.F.; Han, J.

2000-07-01

352

Remote-plasma-enhanced etching of silicon using trifluoro-acetyl-fluoride gas  

Microsoft Academic Search

Recently, it is predicted that most of carbon fluorides, nitrogen trifluoride and sulfur hexafluoride, which are widely used to etch silicon related materials and extremely stable, can induce greenhouse effects. In this study, we demonstrate the acceleration of the etching reaction between silicon and the trifluoroacetyl fluoride (CF3COF) gas, using remote-plasma-excitation at room temperature. The CF3COF is appropriately reactive against

Y. Saito; H. Yamazaki; I. Mouri

2000-01-01

353

Trends in Performance Improvements of a Coaxial Gas-Fed Pulsed Plasma Thruster  

Microsoft Academic Search

The performance of a coaxial gas-fed pulsed plasma thruster is shown to improve with increasing capac- itance. We report experimental results which show that raising the capacitance from 94 µF to 180 µF at a pulse energy of 5 J has uniformly increased the thrust eciency over all specific impulses by a factor of 1.2. Thrust eciencies as high as

J. K. Ziemer; E. Y. Choueiri; Daniel Birx

354

Magnetically-controlled gas breakdown anode plasma sources for magnetically-insulated ion diodes  

Microsoft Academic Search

Summary form only given, as follows. A magnetically insulated extraction-geometry ion diode using inductive breakdown of a gas layer to produce a magnetically controlled anode plasma (MAP) has been successfully operated on the Longshot pulser (120 kV, 30 kA, ⩽?s). This Longshot diode doubled the total ion output compared to a standard dielectric anode, allowed constant impedance for >500 ns,

J. B. Greenly; A. Dunning; K. C. Mittal; G. D. Rondeau

1990-01-01

355

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

Microsoft Academic Search

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

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

1990-01-01

356

Rapid plasma etching of cubic SiC using NF 3\\/O 2 gas mixtures  

Microsoft Academic Search

SiC is known as a chemically inert material. Therefore structuring of SiC by dry chemical processes is difficult and the reported etch rates are usually low. For sensor and micro-machining applications, however, three-dimensional structuring processes of bulk SiC with high etch rates are needed. We made a systematic study of plasma etching processes with NF3\\/O2 gas mixtures. Silicon substrates with

Christoph Richter; Klaus Espertshuber; Christoph Wagner; Martin Eickhoff; Gerhard Krötz

1997-01-01

357

Plasma and fluorocarbon-gas free Si dry etching process using a Cat-CVD system  

Microsoft Academic Search

A heated tungsten filament was used to cataltyze the gas phase etching of crystalline silicon with hydrogen at a substrate temperature of 200°C for obtaining plasma and contamination free etching. Etch rates, between 100 and 200 nm\\/min were obtained in a pure hydrogen ambient in the pressure range of 0.01–0.5 Torr. No etching effect was observed in the case of

Akira Izumi; Hidekazu Sato; Shingi Hashioka; Manabu Kudo; Hideki Matsumura

2000-01-01

358

On-line exhaust gas analytics during plasma cleaning of PECVD facilities  

Microsoft Academic Search

The etching gases usually applied for plasma supported gas phase cleaning of PECVD facilities, i.e. CF4 SF6 and NF3, were checked for their efficiency with regard to silicon containing layers. Even less known etching gases such as ClF3 or pure fluorine were tested. NF3 has the highest etching rate. The etching rates of F2 and ClF3 are only slightly worse.

Andreas E. Guber; Uwe Koehler

1995-01-01

359

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

360

Influence of Gas Heating and Vibrational Kinetics on the Ionization Dynamics of Preformed Air Plasma Channels  

NASA Astrophysics Data System (ADS)

An extensive self-consistent air-plasma model based upon the Boltzmann equation for the electron energy distribution function, coupled with a heavy particle kinetics was developed to study electric discharges in a preexisting air plasma column [1]. Incorporated in the model are the steady-state balance equations for various nitrogen and oxygen species in ground and excited states, as well as atomic and molecular ions. The influence of the gas temperature is accounted for by reduction of the neutral density, collisional processes such as recombination, dissociation, V-V and V-T reactions [2], and by reactions involving electronically excited states of O2. The model was applied to study the influence of the gas temperature and vibrational kinetics on the breakdown processes in a preformed air plasma channel. Numerical calculations predict that electrical breakdown occurs at relatively low electric field. The calculated self-consistent breakdown electric field is ˜10 kV/cm for gas temperature of 300 K, while at temperature of 600 K it drops to ˜5.7 kV/cm, in excellent agreement with the experimentally determined breakdown electric field [1]. * NRC-NRL Postdoc [1] Tz.B. Petrova, H.D. Ladouceur, and A.P. Baronavski, 58th Gaseous Electronics Conference, 2005; San Jose, California, FM.00062 [2] J. Loureiro and C.M. Ferreira, J. Phys. D: Appl. Phys 19 (1986) 17-35

Ladouceur, Harold; Baronavski, Andrew; Petrova, Tzvetelina

2006-03-01

361

Pulsed electromagnetic gas acceleration. [magnetohydrodynamics, plasma power sources and plasma propulsion  

NASA Technical Reports Server (NTRS)

Terminal voltage measurements with various cathodes and anodes in a high power, quasi-steady magnetoplasmadynamic (MPD) are discussed. The magnitude of the current at the onset of voltage fluctuations is shown to be an increasing function of cathode area and a weaker decreasing function of anode area. Tests with a fluted cathode indicated that the fluctuations originate in the plasma adjacent to the cathode rather than at the cathode surface. Measurements of radiative output from an optical cavity aligned to examine the current-carrying portion of a two-dimensional, 56 kA magnetoplasmadynamic discharge reveal no lasing in that region, consistent with calculations of electron excitation and resonance radiation trapping. A voltage-swept double probe technique allows single-shot determination of electron temperature and electron number density in the recombining MPD exhaust flow. Current distributions within the cavity of MPD hollow cathodes for various static prefills with no injected mass flow are examined.

Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

1975-01-01

362

21 CFR 610.12 - Sterility.  

Code of Federal Regulations, 2010 CFR

...sterility testing of biological products, provided...products to be tested by membrane filtration. The...sterility using the membrane filtration procedure...Test Procedures Using Membrane Filtration... (8) Diagnostic biological products not...

2010-04-01

363

21 CFR 610.12 - Sterility.  

Code of Federal Regulations, 2010 CFR

...sterility testing of biological products, provided...products to be tested by membrane filtration. The...sterility using the membrane filtration procedure...Test Procedures Using Membrane Filtration... (8) Diagnostic biological products not...

2009-04-01

364

Sterilization of Human Bone by Irradiation.  

National Technical Information Service (NTIS)

Over the years, irradiation sterilization has been the most widely used sterilization method and one of the most acceptable methods of decontaminating human tissue. It is the purpose of chapter to discuss what is known about the methodology of irradiation...

R. W. Bright J. D. Smarsh V. M. Gambill

1983-01-01

365

21 CFR 886.1940 - Tonometer sterilizer.  

Code of Federal Regulations, 2013 CFR

... A tonometer sterilizer is an AC-powered device intended to heat sterilize a tonometer (a device used to measure intraocular pressure). (b) Classification. Class I (general controls). The device is exempt from the premarket...

2013-04-01

366

Microwave powered sterile access port  

NASA Technical Reports Server (NTRS)

A device and method for elimination of contamination during transfer of materials either into or from bioreactors, food containers, or other microbially vulnerable systems. Using microwave power, thermal sterilizations of mating fixtures are achieved simply, reliably, and quickly by the volatilization of small quantities of water to produce superheated steam which contacts all exposed surfaces.

Sauer, Richard L. (Inventor); Atwater, James E. (Inventor); Dahl, Roger W. (Inventor); Garmon, Frank C. (Inventor); Lunsford, Teddie D. (Inventor); Michalek, William F. (Inventor); Wheeler, Jr., Richard R. (Inventor)

2000-01-01

367

Vapor Hydrogen Peroxide Sterilization Certification  

Microsoft Academic Search

For interplanetary missions landing on a planet of potential biological interest, United States NASA planetary protection currently requires that the flight system must be assembled, tested and ultimately launched with the intent of minimizing the bioload taken to and deposited on the planet. Currently the only NASA approved microbial reduction method is dry heat sterilization process. However, with utilization of

Fei Chen; Shirley Chung; Jack Barengoltz

2010-01-01

368

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

369

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

370

RESPIRATION OF SOIL STERILIZED BY IONIZING RADIATIONS  

Microsoft Academic Search

Electron- and x-ray-sterilized soil respires at a rate approaching that ; of nonsterile soil. Mercuric chloride decreases respiration of sterile soil, ; whereas incubating nonsterile soil with glucose for 48 hours prior to sterilizing ; with x rays increases subsequent respiration. Respiration of dead microbial ; cells may explain, in part, the poor correlation between plate counts and soil ;

GEORGE H. PETERSON

1962-01-01

371

Effects of sterilization processes on NiTi alloy: surface characterization.  

PubMed

Sterilization is required for using any device in contact with the human body. Numerous authors have studied device properties after sterilization and reported on bulk and surface modifications of many materials after processing. These surface modifications may in turn influence device biocompatibility. Still, data are missing on the effect of sterilization procedures on new biomaterials such as nickel-titanium (NiTi). Herein we report on the effect of dry heat, steam autoclaving, ethylene oxide, peracetic acid, and plasma-based sterilization techniques on the surface properties of NiTi. After processing electropolished NiTi disks with these techniques, surface analyses were performed by Auger electron spectroscopy (AES), atomic force microscopy (AFM), and contact angle measurements. AES analyses revealed a higher Ni concentration (6-7 vs. 1%) and a slightly thicker oxide layer on the surface for heat and ethylene oxide processed materials. Studies of surface topography by AFM showed up to a threefold increase of the surface roughness when disks were dry heat sterilized. An increase of the surface energy of up to 100% was calculated for plasma treated surfaces. Our results point out that some surface modifications are induced by sterilization procedures. Further work is required to assess the effect of these modifications on biocompatibility, and to determine the most appropriate methods to sterilize NiTi. PMID:10559750

Thierry, B; Tabrizian, M; Savadogo, O; Yahia, L

2000-01-01

372

Atmospheric-pressure plasma jets: Effect of gas flow, active species, and snake-like bullet propagation  

NASA Astrophysics Data System (ADS)

Cold atmospheric-pressure plasma jets have recently attracted enormous interest owing to numerous applications in plasma biology, health care, medicine, and nanotechnology. A dedicated study of the interaction between the upstream and downstream plasma plumes revealed that the active species (electrons, ions, excited OH, metastable Ar, and nitrogen-related species) generated by the upstream plasma plume enhance the propagation of the downstream plasma plume. At gas flows exceeding 2 l/min, the downstream plasma plume is longer than the upstream plasma plume. Detailed plasma diagnostics and discharge species analysis suggest that this effect is due to the electrons and ions that are generated by the upstream plasma and flow into the downstream plume. This in turn leads to the relatively higher electron density in the downstream plasma. Moreover, high-speed photography reveals a highly unusual behavior of the plasma bullets, which propagate in snake-like motions, very differently from the previous reports. This behavior is related to the hydrodynamic instability of the gas flow, which results in non-uniform distributions of long-lifetime active species in the discharge tube and of surface charges on the inner surface of the tube.

Wu, S.; Wang, Z.; Huang, Q.; Tan, X.; Lu, X.; Ostrikov, K.

2013-02-01

373

A method for measuring plasma arc wind tunnel gas velocity with a position controlled electron beam probe  

Microsoft Academic Search

An electron beam probe has been used in the Micom 8 MW Plasma Facility. Difficulties in applying the probe to measurements of such parameters as gas density were found to be caused by the weak plasma arc-generated magnetic fields producing positional displacements of the beam. This problem was solved by means of a closed-loop electronic controller. Response time of the

Charles Cason

1969-01-01

374

Numerical and experimental study of behavior of gas-puff z-pinch plasma produced by inductive pulsed power generator  

Microsoft Academic Search

Magnetohydrodynamic (MHD) instabilities, such as kink and sausage instabilities, appeared on the gas-puff z-pinch plasma during the pinching process prevent spatial stability of hot spots, which are high energy density plasma regions produced by those instabilities on the z-pinch plasma column locally. Spatial stabilization of hot spots in the axial direction is very important to have practical applications. In this

K. Imasaka; Y. Kawauchi; K. Kawazoe; J. Suehiro; M. Hara

1998-01-01

375

Mechanism of Sterility and Breeding Strategies for Photoperiod\\/ThermoSensitive Genic Male Sterile Rice  

Microsoft Academic Search

To understand the male sterility mechanism of photoperiod\\/thermo-sensitive genic male sterile [P(T)GMS] lines in rice, the research progress on genetics of photoperiod and\\/or temperature sensitive genic male sterility in rice was reviewed. A new idea was proposed to explain the sterility mechanism of P(T)GMS rice. The fertility transition from sterile to fertile is the result of cooperative regulation of major-effect

Li-yun CHEN; Ying-hui XIAO; Dong-yang LEI

2010-01-01

376

Microwave Sterilization and Depyrogenation System  

NASA Technical Reports Server (NTRS)

A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time at a given flow rate. These technologies can be employed in small-scale systems for efficient production of MGW in the laboratory or in a range of larger systems that meet various industrial requirements. The microwave antennas can also be adapted to selectively sterilize vulnerable connections to ultra-pure water production facilities or biologically vulnerable systems where microorganisms may intrude.

Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

2009-01-01

377

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

378

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

NASA Astrophysics Data System (ADS)

A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to H? at 656.3 nm implied an electron density and gas temperature of 2 × 1014 cm-3 and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and H? intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e- --> O + H + e-.

Namba, S.; Yamasaki, T.; Hane, Y.; Fukuhara, D.; Kozue, K.; Takiyama, K.

2011-10-01

379

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

NASA Astrophysics Data System (ADS)

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

Dawood, M. S.; Margot, Joëlle

2014-03-01

380

Investigation of Variation Power and Additive Gas Effect on the $\\\\hbox{SF}_{6}$ Destruction Using Atmospheric Microwave Plasma Torch  

Microsoft Academic Search

An atmospheric microwave plasma torch for the de- composition of SF6 accompanying additive gases (O2, compressed air) was investigated experimentally in this paper. Applied mi- crowave power and additive gas species as effective parameters on destruction and removal efficiency (DRE) were considered. It was approved that compressed air is a more efficient additive gas for the removal of SF6 compared

Zahra Ahmadi; Mohammad Reza Khani; Saeed Kooshki; Fateme Mirzajani; Babak Shokri

2011-01-01

381

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

382

Fast valve and nozzle for gas-puff operation of dense plasma focus  

NASA Astrophysics Data System (ADS)

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 ?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 ?s. This result comes up as an average of about a hundred measurements. The energy input is 95 J (270 V on a 3000 ?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, María M.; Pouzo, Jorge O.; Cortázar, Osvaldo D.; Moroso, Roberto L.

2006-03-01

383

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

384

Ion-plasma protective coatings for gas-turbine engine blades  

NASA Astrophysics Data System (ADS)

Evaporated, diffusion, and evaporation—diffusion protective and hardening multicomponent ionplasma coatings for turbine and compressor blades and other gas-turbine engine parts are considered. The processes of ion surface treatment (ion etching and ion saturation of a surface in the metallic plasma of a vacuum arc) and commercial equipment for the deposition of coatings and ion surface treatment are analyzed. The specific features of the ion-plasma coatings deposited from the metallic plasma of a vacuum arc are described, and the effect of the ion energy on the phase composition of the coatings and the processes occurring in the surface layer of an article to be treated are discussed. Some properties of ion-plasma coatings designed for various purposes are presented. The ion surface saturation of articles made from structural materials is shown to change the structural and phase states of their surfaces and, correspondingly, the related properties of these materials (i.e., their heat resistance, corrosion resistance, fatigue strength, and so on).

Kablov, E. N.; Muboyadzhyan, S. A.; Budinovskii, S. A.; Lutsenko, A. N.

2007-10-01

385

Determination of plasma cholesterol: comparison of gas-liquid chromatographic, colorimetric and enzymatic analyses.  

PubMed

The efficacy of methods for plasma cholesterol analyses based on gas-liquid chromatographic (GLC) or enzymatic cholesterol determinations was tested on commercially available standard serum, plasma obtained in a study of an age stratum of the population and on plasma from a number of patients from an out-patient department. These results were compared with colorimetric cholesterol determinations on chloroform/methanol extracts from plasma using the ferric chloride/sulphuric acid reagent. The GLC-based procedure gave values 12% lower than the colorimetric determinations. This discrepancy seemed to be explained, to a marked extent, by the fact that cholesterol metabolites interfere with the colorimetric determinations. The GLC-based method was apparently accurate since it has the advantage of specificity and is easy to standardize with the internal standard technique. Enzymatic total cholesterol analyses gave slightly (2%) lower values than the GLC-based analyses, apparently because of an incomplete hydrolysis of cholesterol esters. Enzymatic analyses of free cholesterol gave similar results to those of the GLC-based method. PMID:1277537

Lillienberg, L; Svanborg, A

1976-05-01

386

Effect of ambient gas conditions on laser-induced copper plasma and surface morphology  

NASA Astrophysics Data System (ADS)

The effect of different gases and their pressures on the intensity of spectral emission, electron temperature and density of laser-produced plasma has been investigated. For this purpose, Cu targets were ablated by employing Q-switched Nd:YAG laser pulses (?~1064 nm, ?~10 ns, pulsed energy of 200 mJ) under various filling pressures of the background gases argon, air and helium. The optical emission spectroscopy of Cu plasma has been studied using the laser-induced breakdown spectroscopy system. The results obtained strongly indicate that the nature and pressure of the ambient atmosphere are one of the controlling factors of the plasma characteristics. A scanning electron microscopy analysis has been performed to investigate the dependence of surface morphological changes of an irradiated target on the nature and pressure of an ambient gas. The basic aim of this study is to improve the understanding of ablation mechanisms and plasma parameters (optical emission intensity, electron temperature and density) under various ambient conditions. The optimization of experimental conditions (the nature and pressure of the ambient environment) is very important for temperatures and densities of ablated species, which are consequently crucial for pulsed laser deposition of thin films and nanostructuring of materials.

Farid, Nazar; Bashir, Shazia; Mahmood, Khaliq

2012-01-01

387

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

388

[The laparoscopic sterilization of women].  

PubMed

The optimal time for sterilization is 24-36 hours after childbirth or during the 8th week in the postpartum period. The surgical methods of sterilization of the ovarian ducts are simple, harmless, effective, reversible, economical, and voluntary. These considerations also apply to endoscopic methods. For the occlusion of ovarian ducts, electrical current (monopolar and bipolar) and mechanical means (Yoon ring, Hulka and Filshie clips) are used. Unipolar coagulation of the ovarian ducts is another method of surgical sterilization done by laparoscopy. The area of coagulation occupies about 1.5 cm. The length of bipolar coagulation is 10 times larger than the unipolar coagulation site. Patients can be released 4 hours or the next day after the operation. The frequency of complications with bipolar coagulation is low: burning occurs in 0.04-0.1% of cases and bleeding from the mesosalpinx in 0.16-0.5%. The incidence of pregnancy after the operation amounts to 0.1-0.4%. Mechanical methods of sterilization are also reliable, although they are not suitable for all women. For young women who may still want children it is uniquely expedient to employ the Hulka or Filshie clips. In the rest of the cases the Yoon ring can be used, which was first used in the US in 1972 and became popular subsequently. The rate of complications is rare with its use (0.12-3.75%), and pregnancy occurs in 0.08-0.4% of cases. The incidence of complications with the use of clips amounts to 0-0.71%, the pregnancy rate is 0-0.59%, and the possibility of reversal is 80-100%. This method is ideal for young women who do not want to use other contraceptives and who want to have more children. PMID:8579209

Dzhabrailova, S Sh

1995-01-01

389

Method of sterilization using ozone  

NASA Technical Reports Server (NTRS)

Methods of using ozone have been developed which sterilize instruments and medical wastes, oxidize, organics found in wastewater, clean laundry, break down contaminants in soil into a form more readily digested by microbes, kill microorganisms present in food products, and destroy toxins present in food products. The preferred methods for killing microorganism and destroying toxins use pressurized, humidified, and concentrated ozone produced by an electrochemical cell.

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor)

2002-01-01

390

Gas plasma treatment of cathodes to improve Li/SO{sub 2} cell performance  

SciTech Connect

One rapid way to alter pendant groups on surfaces and/or to clean surfaces is to expose them briefly to low pressure, room, temperature gas plasmas. In this paper, the authors present results of using this simple vapor process to pretreat fabricated, porous carbon cathodes which were then assembled in spirally wound, hermetically sealed squat ``D`` sized Li/SO{sub 2} cells (PCI Model G-70). Overall cell performance such as start-up times, load voltage, and ampere-hour capacity were monitored before and after 28 days storage at 71 C. Performance during 3 A discharge at {minus}29 C was enhanced in cells containing plasma-treated cathodes. This treatment procedure should be of practical interest because fabricated carbon cathodes of any size can be quickly processed during normal manufacturing.

Binder, M.; Mammone, R.J. [Army Electronics and Power Sources Directorate, Fort Monmouth, NJ (United States). Energy Sciences Branch; Thurston, E.P.; Reddy, T.B. [Power Conversion Inc., Elmwood Park, NJ (United States)

1993-12-01

391

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

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

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

NASA Technical Reports Server (NTRS)

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

Tidman, D. A.

1972-01-01

394

Sterile neutrinos as dark matter  

SciTech Connect

The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed or sterile neutrinos. This model has been studied extensively in the context of the hot dark matter scenario. We reexamine this model and find that hot, warm, and cold dark matter are all possibilities. We focus on the case where sterile neutrinos are the dark matter. Since their only direct coupling is to left-handed or active neutrinos, the most efficient production mechanism is via neutrino oscillations. If the production rate is always less than the expansion rate, then these neutrinos will never be in thermal equilibrium. However, they may still play a significant role in the dynamics of the Universe and possibly provide the missing mass necessary for closure. We consider a single generation of neutrino fields ({nu}{sub L}, {nu}{sub R}) with a Dirac mass, {mu}, and a Majorana mass for the right-handed components only, M. For M {much_gt} {mu} we show that the number density of sterile neutrinos is proportional to {mu}{sup 2}/M so that the energy density today is independent of M. However M is crucial in determining the large scale structure of the Universe. In particular, M {approx_equal} 0.1--1.0 key leads to warm dark matter and a structure formation scenario that may have some advantages over both the standard hot and cold dark matter scenarios.

Dodelson, S. [Fermi National Accelerator Lab., Batavia, IL (United States); Widrow, L.M. [Queen`s Univ., Kingston, ON (Canada). Dept. of Physics]|[Toronto Univ., ON (Canada). Canadian Inst. for Theoretical Astrophysics

1993-03-01

395

Sterile neutrinos as dark matter  

SciTech Connect

The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed or sterile neutrinos. This model has been studied extensively in the context of the hot dark matter scenario. We reexamine this model and find that hot, warm, and cold dark matter are all possibilities. We focus on the case where sterile neutrinos are the dark matter. Since their only direct coupling is to left-handed or active neutrinos, the most efficient production mechanism is via neutrino oscillations. If the production rate is always less than the expansion rate, then these neutrinos will never be in thermal equilibrium. However, they may still play a significant role in the dynamics of the Universe and possibly provide the missing mass necessary for closure. We consider a single generation of neutrino fields ([nu][sub L], [nu][sub R]) with a Dirac mass, [mu], and a Majorana mass for the right-handed components only, M. For M [much gt] [mu] we show that the number density of sterile neutrinos is proportional to [mu][sup 2]/M so that the energy density today is independent of M. However M is crucial in determining the large scale structure of the Universe. In particular, M [approx equal] 0.1--1.0 key leads to warm dark matter and a structure formation scenario that may have some advantages over both the standard hot and cold dark matter scenarios.

Dodelson, S. (Fermi National Accelerator Lab., Batavia, IL (United States)); Widrow, L.M. (Queen's Univ., Kingston, ON (Canada). Dept. of Physics Toronto Univ., ON (Canada). Canadian Inst. for Theoretical Astrophysics)

1993-03-01

396

Determination of plasma density and ion temperature using hydrogen radiation spectral measurements in a gas-dynamic trap  

NASA Astrophysics Data System (ADS)

A diagnostics complex for measurement of plasma parameters in a gas-dynamic trap (GDT) using hydrogen radiation lines is described. Physical bases of the diagnostics method for ion temperature determination are presented; recording equipment is described. The results of measurements at GDT installation under plasma heating conditions using atomic beam injection are discussed. The method for measuring spatial distribution of plasma density in the cross section of a plasma filament is suggested; the results of preliminary experiments showing principle possibility of its realization are presented.

Zinovev, A. N.; Krzhizhanovskij, E. R.; Ivanoc, A. A.; Klesov, V. V.

397

High-Beta, Anisotropic Plasma Confinement in an Axially Symmetric Gas Dynamic Trap  

NASA Astrophysics Data System (ADS)

In the Gas Dynamic Trap (GDT) axially symmetric magnetic mirror, measurements have confirmed that on-axis transverse beta approximately equal to 40% is achieved in the fast ion turning points [A.A. Ivanov et al., Phys. Rev. Lett. 90, 105002 (2003)]. In GDT, oblique injection of 4 MW of 17 keV deuterium neutral beams into a warm (<100 eV) target plasma produces a population of anisotropic fast deuterons, which oscillate back and forth between the turning points near the end mirrors ("sloshing" ions). Since the fast ions spend a large fraction of a bounce time near the turning points, their density and temperature are strongly peaked (10^19 m-3, 10 keV) in these regions. The measured beta is close to the theoretical prediction of the MHD stability threshold for ballooning modes in this mirror trap. GDT is stable against interchange modes due to average good curvature along a magnetic field line. This is provided by sufficiently high density of the target plasma in the axially symmetric end cells, where the magnetic field lines contribute substantial good curvature. The collisional target plasma is confined in the mirror as if it were an ideal gas in a container with pinhole leaks. Ions are lost out of the mirrors with the rate of an ion-acoustic speed. At the same time, the fast ion angular distribution remains quite narrow and centered on the initial value of the pitch angle. Neither enhanced transverse losses of the plasma nor anomalies in the fast ion scattering and slowing down were observed in experiments. Measured D-D neutron flux is peaked in the turning points; these are the same regions that house the testing zones in the projected GDT-based neutron source. The measured beta and axial profile of the D-D neutron flux are similar to that required for a 14 MeV neutron source for fusion materials testing.

Lizunov, A. A.

2003-10-01

398

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

NASA Astrophysics Data System (ADS)

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). In this work, the neutral temperature was estimated using this technique for flowing discharges of argon, helium, neon, nitrogen, and oxygen as a function of pressure and power. It was found that the neutral temperature for all of the discharges studied increased roughly proportional to the logarithm of the pressure. An increase in neutral temperature was also observed with increases in power; however, the dependence did not follow a simple functional form. The rare gases exhibited temperatures significantly above room temperature under high power (1200 W) and high pressure (approx1 Torr) conditions with argon approaching 2000 K. Molecular discharges such as N2 and O2 exhibited significantly higher temperatures (approaching 2500 K) than the rare gases even though they are expected to have lower plasma densities at the same pressure and power. It is believed that Franck-Condon heating of the gases during electron impact dissociation, vibrational excitation/thermalization, and exothermic wall reactions may all play important roles in producing such elevated temperatures. Simple, zero-dimensional plasma modeling indicates that neutral temperature elevation will result in significant increases in discharge electron temperature and electron-impact reaction rate coefficients under the same operating conditions. copyright 2002 American Vacuum Society.

Tonnis, Eric J.; Graves, David B.

2002-09-01

399

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

2007-01-01

400

Radiation sterilization of enzyme hybrids with biodegradable polymers  

Microsoft Academic Search

Ionizing radiations, which have already been utilized for the sterilization of medical supplies as well as gas fumigation, should be the final candidate to decontaminate “hybrid” biomaterials containing bio-active materials including enzymes because irradiation induces neither heat nor substances affecting the quality of the materials and our health. In order to check the feasibility of 60Co-gamma rays on these materials,

Masakazu Furuta; Masahito Oka; Toshio Hayashi

2002-01-01

401

Stark broadening along a homologous sequence of noble gas atomic lines in dense plasmas  

NASA Astrophysics Data System (ADS)

The authors present experimental results on the broadening and shift of some rare gas atomic lines emitted by high electron density plasmas created in linear flashtubes. From a semi-empirical formula, they find a theoretical dependence of the Stark broadening parameters on the ionisation potential for lines broadened by electron impacts. Experimentally, a non-linear dependence is found between the Stark width w and shift d, and the electron density. At the lowest electron density, the authors' values of w and d agree with other experimental determinations. The authors have observed a regularity of w and d for analogous lines of homologous atoms.

Vitel, Y.; Skowronek, M.; Dimitrijevic, M. S.; Popovic, M. M.

1988-07-01

402

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

403

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

404

Evaluation of Parameters Affecting Arc Plasma Chute in a Typical Gas Interrupter  

NASA Astrophysics Data System (ADS)

In this study, we examined a typical high-voltage gas circuit breaker. The main goal of this study is to characterize arc plasma and to determine its behavior using the generalized Mayr-type equation model following the interruption of high-voltage circuit breakers according to a semi-empirical one, named conductance model. Here, we tried to evaluate some arc parameters that affect interrupting ability by performing a numerical analysis so that our model defines recorded experimental results of an actual test.

Borghei, Seyed Majid; Ghoranneviss, Mahmood; Abolhassani, Mohammad Reza; Anvari, Abbas

2008-01-01

405

Determination of n-butylated trialkyllead compounds by gas chromatography with microwave plasma emission detection  

SciTech Connect

An analytical gas chromatographic procedure is described for the determination of trialkyllead compounds in aqueous media. The analyte compounds are extracted into benzene from an aqueous solution saturated with sodium chloride. They are then quantitatively converted into n-butyltrialkyllead derivatives by reaction with an n-butyl Grignard reagent. Precolumn Tenax trap enrichment of the derived trialkylbutylleads enables determination to low parts per billion levels to be carried out. Also investigated are extraction efficiencies and injection split ratios onto a fused silica capillary column. Lead specific detection is by atmospheric pressure microwave induced plasma spectrometric emission. Data are presented for a wastewater effluent sample. 3 figures.

Estes, S.A.; Uden, P.C.; Barnes, R.M.

1982-12-01

406

Determination of n-butylated trialkyllead compounds by gas chromatography with microwave plasma emission detection  

SciTech Connect

An analytical gas chromatographic procedure is described for the determination of trialkyllead compounds in aqueous media. The analyte compounds are extracted into benzene from an aqueous solution saturated with sodium chloride. They are then quantitatively converted into n-butyltrialkyllead derivatives by reaction with an n-butyl Grignard reagent. Precolumn Tenax trap enrichment of the derived trialkylbutylleads enables determination to low ppB levels to be carried out. Also investigated are extraction efficiencies and injection split ratios onto a fused silica capillary column. Lead specific detection is by atmospheric pressure microwave induced plasma spectrometric emission. Data are presented for a wastewater effluent sample. 21 references, 3 figures.

Estes, S.A.; Uden, P.C.; Barnes, R.M.

1982-12-01

407

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

NASA Technical Reports Server (NTRS)

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

Bill, R. C.

1979-01-01

408

Characterization of pulse-driven gas-liquid interfacial discharge plasmas and application to synthesis of gold nanoparticle-DNA encapsulated carbon nanotubes  

Microsoft Academic Search

Gas-liquid interfacial discharge plasmas are generated between ionic liquid and stainless steel electrodes, where a pulse power source is used to operate the discharges. The temporal evolution of the plasma is investigated as well as the spatial distribution of the plasma. The positive pulse discharge plasma can not be detected by a double Langmuir probe, which is attributed to the

Qiang Chen; Toshiro Kaneko; Rikizo Hatakeyama

409

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

410

High pressure laser plasma studies. [energy pathways in He-Ar gas mixtures at low pressure  

NASA Technical Reports Server (NTRS)

The operation of a nuclear pumped laser, operating at a wavelength of 1.79 micron m on the 3d(1/2-4p(3/2) transition in argon with helium-3 as the majority gas is discussed. The energy pathways in He-Ar gas were investigated by observing the effects of varying partial pressures on the emissions of levels lying above the 4p level in argon during a pulsed afterglow. An attempt is made to determine the population mechanisms of the 3d level in pure argon by observing emission from the same transition in a high pressure plasma excited by a high energy electron beam. Both collisional radiative and dissociative recombination are discussed.

Wells, W. E.

1980-01-01

411

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

SciTech Connect

An experimental study on gas analysis by means of laser-induced breakdown spectroscopy was conducted using a Nd-yttrium aluminum garnet laser (1,064 nm, 120 mJ, 8 ns) and helium host gas at atmospheric pressure on a sample of mixed water (H{sub 2}O) and heavy water (D{sub 2}O) in vapor form. It was shown that completely resolved hydrogen (H{sub {alpha}}) and deuterium (D{sub {alpha}}) emission lines that are separated by only 0.179 nm could be obtained at a properly delayed detection time when the charged particles responsible for the strong Stark broadening effect in the plasma have mostly disappeared. It is argued that the helium metastable excited state plays an important role in the hydrogen excitation process.

Kurniawan, Koo Hendrik; Lie, Tjung Jie; Suliyanti, Maria Margaretha; Hedwig, Rinda; Abdulmadjid, Syahrun Nur; Pardede, Marincan; Idris, Nasrullah; Kobayashi, Takao; Kusumoto, Yoshihumi; Kagawa, Kiichiro; Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Department of Fiber Amenity, Graduate School of Engineering, Fukui University, 9-1 Bunkyo 3-chome, Fukui 910 (Japan); Department of Chemistry and Bio-Science, Faculty of Science, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan); Department of Physics, Faculty of Education and Regional Studies, 9-1 Bunkyo 3-chome, Fukui 910 (Japan); Department of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia)

2005-11-01

412

Developpement et utilisation de sources de plasma pour steriliser des instruments medicaux  

NASA Astrophysics Data System (ADS)

Advances in plasma sterilization of medical devices (MDs) are dependent upon both the development of plasma sources adapted to the processing of these MDs, and upon the understanding of the inactivation mechanisms of microorganisms. The main objectives of this thesis were, on the one hand, to develop plasma sources that are spatially uniform and that have a low gas temperature (< 50°C) and, on the other hand, the identification and optimization of biocidal agents (e.g. UV radiation) in their plasmas. In the course of this work, we have designed and developed three types of electromagnetic field applicators to sustain plasma. The first was a network of distributed antennas on the outside of the dielectric discharge-vessel, which possessed multiple high-frequency (HF) input ports fed by a waveguide-based power divider. This distributed source concept was soon abandoned in favour of two other plasma source designs, since the latter ones provided immediate advantages for biomedical sterilization, and also in terms of energy efficiency and frequency bandwidth (e.g. near-constant input impedance). These two plasma sources are based on planar transmission line designs where the plasma is part of the transmission line: the first allows one to sterilize the inner surfaces (lumen) of thermally sensitive dielectric tubes (e.g. cardiac catheters), while the other enables one to immerse three-dimensional objects within the plasma (e.g. forceps). Two types of microorganisms were used to test the performances to identify and to optimise the biocidal agents of the plasma sources that we have developed namely, sedimented bacterial spores from a suspension of Bacillus atrophaeus and vegetative Staphylococcus aureus bacteria embedded in a biofilm matrix. Inactivation of these microorganisms in our plasma sterilizers results through irradiation. This sterilization process is rapid (a few minutes), non-toxic (it does not require venting), and it affects thermally sensitive polymers relatively little (no erosion was detected). Keywords: high-frequency (HF) plasma sources, input impedance, planar transmission lines, sterilization, bacterial spores, biofilm, thermally sensitive medical devices (MDs).

Pollak, Jerome

413

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

NASA Astrophysics Data System (ADS)

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

Maksimchuk, Anatoly

2007-11-01

414

Hazard and operability study of an ethylene oxide sterilizer for National Institute for Occupational Safety and Health. Final report  

SciTech Connect

A hazard and operability (HAZOP) study was conducted on a sterilizer supplied by compressed gas cylinders of ethylene-oxide (EtO). The sterilizer installation, equipment, and operational procedures were reviewed, and recommendations were developed both specifically for the studied installation and for the generic installation. The sterilizer consisted of a jacketed chamber and associated pumps, pipes, filters, valves and other equipment. Sterilizer facility design, sterilizer equipment design, leak monitoring, system utilities, equipment maintenance, and operational procedures were discussed. These recommendations should provide guidance to hospitals installing EtO sterilizers. The study also showed how the HAZOP study procedures which are typically used in large chemical facilities can be used on a small scale setting. The HAZOP study involved evaluating the facility as a series of systems. Log sheets of information gathered were included in the report. A process diagram of an EtO sterilizer was included along with a schematic of EtO piping from tanks to sterilizer, a schematic of EtO sample line, calibration gas line, and carrier gas line, and schematics of the air inlet line to chamber and the piping from EtO tank to supply valve.

Not Available

1988-12-01

415

Diagnostics of nitrogen plasma by trace rare-gas-optical emission spectroscopy  

SciTech Connect

Trace rare-gas-optical emission spectroscopy is carried out to characterize the nitrogen plasma as a function of discharge parameters. The functional dependence of N{sub 2}(C {sup 3}{pi}{sub u}) and N{sub 2}{sup +}(B {sup 2}{sigma}{sub u}{sup +}) excited states is monitored by measuring the emission intensities of the bandheads of second positive and first negative systems. The excited-state population density of N atoms and N{sub 2} molecules, extracted from their optical emission, is related to the ground-state population density after normalizing the changes for excitation cross section and electron energy distribution function by optical actinometry. The electron temperature is determined from the plasma-induced optical emission of trace rare gas by the line-to-line method. The obtained data may help us to adjust the optimum discharge conditions for the production of active species, which are considered to be important for the desired treatment of the samples.

Qayyum, A.; Zeb, Shaista; Naveed, M.A.; Ghauri, S.A.; Zakaullah, M.; Waheed, A. [Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Pakistan Institute of Nuclear Science and Technology (PINSTECH), P.O. Box 2151, 44000 Islamabad (Pakistan)

2005-11-15