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1

Gas plasma sterilization--application of space-age technology.  

PubMed

Gas plasma sterilization is new to the healthcare field. The first such sterilizer has been manufactured by Advanced Sterilization Products (J&J, Irvine, CA). The system uses hydrogen peroxide as the substrate gas and radio frequency emissions to generate plasma. This system is a low-temperature, quick-acting process with no toxic residues. It appears that this sterilizer system holds promise in the healthcare field and could help to reduce the use of ethylene oxide. PMID:7594394

Crow, S; Smith, J H

1995-08-01

2

Gas Plasma Sterilization: Application of Space-Age Technology  

Microsoft Academic Search

Gas plasma sterilization is new to the healthcare field. The first such sterilizer has been manufactured by Advanced Sterilization Products (J&J, Irvine, CA). The system uses hydrogen peroxide as the substrate gas and radio frequency emissions to generate plasma. This system is a low-temperature, quick-acting process with no toxic residues. It appears that this sterilizer system holds promise in the

Sue Crow; John H. Smith III

1995-01-01

3

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

4

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

NASA Astrophysics Data System (ADS)

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

Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

2015-01-01

5

Apparatus Circulates Sterilizing Gas  

NASA Technical Reports Server (NTRS)

Apparatus circulates sterilizing gas containing ethylene oxide and chlorofluorocarbon through laboratory or medical equipment. Confines sterilizing gas, circulating it only through parts to be treated. Consists of two units. One delivers ethylene oxide/chlorofluorocarbon gas mixture and removes gas after treatment. Other warms, humidifies, and circulates gas through equipment to be treated. Process provides reliable sterilization with negligible residual toxicity from ethylene oxide. Particularly suitable for sterilization of interiors of bioreactors, heart/lung machines, dialyzers, or other equipment including complicated tubing.

Cross, John H.; Schwarz, Ray P.

1991-01-01

6

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

7

Characteristics of surface-wave plasma with air-simulated N2 O2 gas mixture for low-temperature sterilization  

NASA Astrophysics Data System (ADS)

Sterilization experiments using low-pressure air discharge plasma sustained by the 2.45 GHz surface-wave have been carried out. Geobacillus stearothermoplilus spores having a population of 3.0 × 106 were sterilized for only 3 min using air-simulated N2-O2 mixture gas discharge plasma, faster than the cases of pure O2 or pure N2 discharge plasmas. From the SEM analysis of plasma-irradiated spores and optical emission spectroscopy measurements of the plasmas, it has been found that the possible sterilization mechanisms of air-simulated plasma are the chemical etching effect due to the oxygen radicals and UV emission from the N2 molecules and NO radicals in the wavelength range 200-400 nm. Experiment suggested that UV emission in the wavelength range less than 200 nm might not be significant in the sterilization. The UV intensity at 237.0 nm originated from the NO ? system (A 2?+ ? X 2?) in N2-O2 plasma as a function of the O2 percentage added to N2-O2 mixture gas has been investigated. It achieved its maximum value when the O2 percentage was roughly 10-20%. This result suggests that air can be used as a discharge gas for sterilization, and indeed we have confirmed a rapid sterilization with the actual air discharge at a sample temperature of less than 65 °C.

Xu, L.; Nonaka, H.; Zhou, H. Y.; Ogino, A.; Nagata, T.; Koide, Y.; Nanko, S.; Kurawaki, I.; Nagatsu, M.

2007-02-01

8

Plasma sterilization using the RF glow discharge  

NASA Astrophysics Data System (ADS)

In the present work, glow discharge oxygen plasma was used to sterilize the Pseudomonas aeruginosa on the polyethylene terephthalate (PET) sheets. In a self-designed plasma reaction equipment, active species (electron, ion, radical, UV light, etc.) were separated effectively, and the discharge area, afterglow area and remote area were plotted out in the plasma field. Before and after plasma treatment the cell morphology was studied by scanning electron microscopy (SEM). The results showed that after treatment of 30 s the germicidal effect is 4.26, 3. 84, 2.61, respectively in the three areas on the following conditions: discharge power was 40 W and gas flux was 20 cm 3/min. SEM results revealed the cell morphology before and after plasma treatment. The walls or cell membrane cracking was testified by determining the content of protein using coomassie light blue technique. The results from electron spin resonance spectroscopy (ESR) and double Langmuir electron probe showed that electron, ion and oxygen free radical played important roles in sterilization in the discharge area, but only oxygen radicals acted to sterilize the bacteria in the afterglow area and the remote area.

Yang, Liqing; Chen, Jierong; Gao, Junling; Guo, Yafei

2009-08-01

9

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

Microsoft Academic Search

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

Ozlem Yardimci; Peter Setlow

2010-01-01

10

Plasma Sterilization: New Epoch in Medical Textiles  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

11

Features of Sterilization Using Low Pressure DC Discharge Hydrogen Peroxide Plasma  

Microsoft Academic Search

This investigation studies the theoretical and practical features of sterilization using glow discharge plasma in hydrogen peroxide vapor. It is determined that, in such a system, most sterilization is performed by active particles formed in the plasma, rather than by ultraviolet (UV) radiation (as is the case in gas discharges like air and oxygen). This study shows that sterilization by

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

12

PLASMA STERILIZATION Plasma sterilization is fast evolving into a promising alternative to standard  

E-print Network

alternative to standard sterilizing techniques. Research on plasma sterilization started way back in 1960-organisms. · Autoclaving- Autoclaving uses very high temperatures to effectively kill any pathogens. · EtOH- Ethylene oxide temperature and hence poses no dangers associated with high temperatures (unlike autoclaves) · Doesn't involve

Roy, Subrata

13

Gas dynamics of ethylene oxide during sterilization  

NASA Astrophysics Data System (ADS)

This article reports a case study of the dynamics of ethylene oxide gas during sterilization using a microwave spectrometer. A diffusion equation is used to describe the processes of gas penetration, gas sorption, and chemical reactions. The three processes, although mathematically related, may be solved separately under simplified assumptions. This permits the prediction of gas penetration and sorption as well as the effect of chemical reactions upon the gas concentration for loads of differing dimensions and densities.

Zhu, Z.; Matthews, I. P.; Wang, C.

1999-07-01

14

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

15

21 CFR 880.6860 - Ethylene oxide gas sterilizer.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Ethylene oxide gas sterilizer. 880.6860 Section...Miscellaneous Devices § 880.6860 Ethylene oxide gas sterilizer. (a) Identification...health care provider that uses ethylene oxide (ETO) to sterilize medical...

2012-04-01

16

21 CFR 880.6860 - Ethylene oxide gas sterilizer.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Ethylene oxide gas sterilizer. 880.6860 Section...Miscellaneous Devices § 880.6860 Ethylene oxide gas sterilizer. (a) Identification...health care provider that uses ethylene oxide (ETO) to sterilize medical...

2011-04-01

17

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

NASA Astrophysics Data System (ADS)

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

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

18

Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 2.Sterilization by Electrical Discharges and Plasmas  

Microsoft Academic Search

The use of electrical discharges and plasmas for sterilization is reviewed. Plasmas generated by a silent discharge, a pulse discharge, and a radio frequency discharge under atmospheric pressure have been used for sterilization. Furthermore, a microwave plasma, a radio frequency plasma, and a low temperature plasma with hydrogen peroxide under low pressure conditions have been also used for sterilization. Sterilization

Takayuki Watanabe

1999-01-01

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

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

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

Release of gas residues from an ethylene oxide sterilized haemodialyser.  

PubMed

Ethylene oxide, a toxic gas used as sterilant for medical devices, is absorbed in plastic materials. The gas is desorbed from the sterilized devices occasionally leading to injuries to the users. A photoionization detector, being specific and sensitive, is used for measurement of liberated ethylene oxide from a haemodialyser. The detector, used as a flow through cell direct connected to the haemodialyser, enables measurement of ethylene oxide in quantities ten times smaller than the maximum daily exposure. PMID:6640061

Hoy, K; Handlos, V

1983-10-01

23

Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma  

NASA Astrophysics Data System (ADS)

Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1?g), and 2.9 x 10^12 cm-3 O2(^1?^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1?g) metastables were responsible for killing the anthrax and other microorganisms.

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

2009-10-01

24

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

25

Features of sterilization using low-pressure DC-discharge hydrogen-peroxide plasma  

Microsoft Academic Search

This investigation studies the theoretical and practical features of sterilization using glow discharge plasma in hydrogen-peroxide vapor. It is determined that in such a system, most sterilization is performed by the active species formed in the plasma rather than by ultraviolet radiation (as is the case in air or oxygen discharges). This study shows that sterilization by discharge plasma in

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

2002-01-01

26

Comparison of two radio-frequency plasma sterilization processes using microspot evaluation of microbial inactivation.  

PubMed

In this study, we evaluated gas plasma surface sterilization methods in a specific sterilizer. We have introduced a new monitoring method using 0.4 microm pore size membranes, which in this study gave the information corresponding to 3000 exposed biological indicators per treatment cycle. This enabled us to compare the fraction of inoculates that showed no growth after exposure for 30 different locations in the chamber, and hereby identify weak and strong spots in the chamber with regard to sporicidal effect. Membranes were also used to expose a broad spectrum of soil bacteria for plasma treatment at four different conditions. The organisms were identified using PCR and sequencing. The test showed that Bacillus stearothermophilus spores were inactivated at the slowest rate among the tested microorganisms. Further alpha-proteobacteria (Gram negative) seemed more sensitive than the rest of the tested organisms. The microspot evaluation approach has been a most useful tool in the assessment of sterilization performance in sterilizers that do not have clear measurable parameters related to the sterilization. PMID:16362959

Lassen, Klaus S; Johansen, Jens E; Grün, Reinar

2006-07-01

27

Sterilization.  

PubMed

Worldwide, sterilization (tubal sterilization and vasectomy) is used by more people than any other method of contraception. All techniques of tubal sterilization in widespread use in the United States have low risks of surgical complications. Although tubal sterilization is highly effective, the risk of pregnancy varies by age and method of occlusion. Pregnancies can occur many years after the procedure, and when they do, the risk of ectopic gestation is high. There is now strong evidence against the existence of a post-tubal ligation syndrome of menstrual abnormalities. Although women who have undergone tubal sterilization are more likely than other women to undergo hysterectomy subsequently, there is no known biologic basis for this relationship. Although sterilization is intended to be permanent, expressions of regret and requests for reversal are not uncommon and are much more likely to occur among women sterilized at young ages. Tubal sterilization has little or no effect on sexual function for most women. Vasectomy is less likely than tubal sterilization to result in serious complications. Minor complications, however, are not uncommon. Vasectomy does not increase the risk of heart disease, and available evidence argues against an increase in the risk of prostate cancer, testicular cancer, or overall mortality. Whether a postvasectomy pain syndrome exists remains controversial. Although the long-term effectiveness of vasectomy is less well-studied than that for tubal sterilization, it seems likely to be at least as effective. Intrauterine devices and progestin implants are long-acting, highly effective alternatives to sterilization. PMID:18165410

Peterson, Herbert B

2008-01-01

28

Comparison of Sterilizing Effect of Nonequilibrium Atmospheric-Pressure He\\/O2 and Ar\\/O2 Plasma Jets  

Microsoft Academic Search

The sterilizing effect of the non-equilibrium atmospheric pressure plasma jet by applying it to the Bacillus subtilis spores is invesigated. A stable glow discharge in argon or helium gas fed with active gas (oxygen), was generated in the coaxial cylindrical reactor powered by the radio-frequency power supply at atmospheric pressure. The experimental results indicated that the efficiency of killing spores

Shouzhe Li; Jinpyo Lim

2008-01-01

29

Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 2.Sterilization by Electrical Discharges and Plasmas  

NASA Astrophysics Data System (ADS)

The use of electrical discharges and plasmas for sterilization is reviewed. Plasmas generated by a silent discharge, a pulse discharge, and a radio frequency discharge under atmospheric pressure have been used for sterilization. Furthermore, a microwave plasma, a radio frequency plasma, and a low temperature plasma with hydrogen peroxide under low pressure conditions have been also used for sterilization. Sterilization results from injury caused by the discharge current, and from the reaction of species affected by the discharge. A silent discharge with air or oxygen is most effective for the sterilization. Nitrogen discharge also has a significant effect, however, argon discharge does not have a significant effect.

Watanabe, Takayuki

30

An overview of modelling of low-pressure post-discharge systems used for plasma sterilization  

NASA Astrophysics Data System (ADS)

We present the modeling of a low pressure post-discharge system used for plasma sterilization, which consists of a flowing microwave discharge, an early-afterglow region developed downstream of the discharge in the same tube, and a large post-discharge reactor. The kinetic model valid for the discharge and early-afterglow region is based on the Boltzmann and rate balance equations, while in the post-discharge reactor a 3-D hydrodynamic model is used. The calculations are conducted in an N2-O2 mixture, which has seen to constitute an efficient system for sterilization purpose. The possibilities offered by modeling is presented through a discussion of the effects on relevant species densities and distributions caused by varying: (i) the initial gas mixture composition; (ii) the length of early-afterglow zone; (iii) the gas flow rate and gas pressure.

Kutasi, K.; Pintassilgo, C. D.; Loureiro, J.

2009-04-01

31

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

PubMed

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

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

2013-01-01

32

Sterilization.  

PubMed

Male and female sterilization is a safe and effective form of permanent contraception. The number of patients accepting this method has rapidly increased over the last ten years and is likely to continue. In some countries the rate has plateaued out: in the USA it has been 31 per cent of all married women for the last eight years. Before sterilization it is important that adequate counselling is given to both partners and that the decision is not hurried. This is emphasized by the number of women and men requesting reversal of sterilization (thought to be between 0.1 and 10 per cent of all sterilizations). These requests for reversal usually come from couples who have remarried, tend to be younger, have fewer live children, have had more abortions, less schooling and are poor users of contraception. In these high-risk patients counselling and time to make the decision is essential. Other studies indicate that regret after puerperal sterilization may be commoner, but the risks of further pregnancies have to be weighed against sterilization regret. The methodology of male sterilization has changed little in the last ten years; it is simple and usually done under local anaesthesia. In contrast, female sterilization methods are constantly being refined, from laparotomy to laparoscopy and from extensive tubal destruction or excision to minimal tubal damage. The common methods now are mini-laparotomy and laparoscopy under local or general anaesthesia, with tubal occlusion by clips, rings or bipolar or thermal coagulation. There is no place now for unipolar diathermy, because of the higher complication rate, especially for major complications such as bowel burns. Recent multicentre studies comparing different methods give low rates for immediate morbidity and surgical complications (0.8 to 2.5 per cent of cases). Technical failure is rare but often due to a pre-existing condition, for example obesity or previous pelvic disease. Some failures are due, however, to difficulties with the instruments, especially at laparoscopy; here further developments and the use of teaching aids for those in training will help to reduce problems. Mortality from female sterilization is low, at 2 to 10 per 100 000 procedures; however, half is due in part to anaesthetic complications (hypoventilation), which can be avoided by intubation, and others are due to pre-existing medical conditions. Long-term follow-up has now shown that sterilization does not cause an increase in menstrual blood loss.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6239731

Newton, J R

1984-12-01

33

Sterilization by Low-Pressure Plasma: The Role of Vacuum-Ultraviolet Radiation  

Microsoft Academic Search

Low-pressure plasma is a promising method for destroying microorganisms, an alternative to “conventional” methods, which have numerous drawbacks. Several plasma-based sterilization technologies are presently under development, even though the exact role of the various plasma constituents, for example ultraviolet radiation, on the sterilization mechanism is still unknown and subject to controversy. In this study, we first report high sporicidal activity

S. Lerouge; A. C. Fozza; M. R. Wertheimer; R. Marchand; L‘H. Yahia

2000-01-01

34

Comparison of Sterilizing Effect of Nonequilibrium Atmospheric-Pressure He/O2 and Ar/O2 Plasma Jets  

NASA Astrophysics Data System (ADS)

The sterilizing effect of the non-equilibrium atmospheric pressure plasma jet by applying it to the Bacillus subtilis spores is invesigated. A stable glow discharge in argon or helium gas fed with active gas (oxygen), was generated in the coaxial cylindrical reactor powered by the radio-frequency power supply at atmospheric pressure. The experimental results indicated that the efficiency of killing spores by making use of an Ar/O2 plasma jet was much better than with a He/O2 plasma jet. The decimal reduction value of Ar/O2 and He/O2 plasma jets under the same experimental conditions was 4.5 seconds and 125 seconds, respectively. It was found that there exists an optimum oxygen concentration for a certain input power, at which the sterilization efficiency reaches a maximum value. It is believed that the oxygen radicals are generated most efficiently under this optimum condition.

Li, Shouzhe; Lim, Jinpyo

2008-02-01

35

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

Microsoft Academic Search

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.

Han S. Uhm; Jin P. Lim; Shou Z. Li

2007-01-01

36

Characterization of stationary and pulsed inductively coupled RF discharges for plasma sterilization  

Microsoft Academic Search

Sterilization of bio-medical materials using radio frequency (RF) excited inductively coupled plasmas (ICPs) has been investigated. A double ICP has been developed and studied for homogenous treatment of three-dimensional objects. Sterilization is achieved through a combination of ultraviolet light, ion bombardment and radical treatment. For temperature sensitive materials, the process temperature is a crucial parameter. Pulsing of the plasma reduces

T. Gans; M. Osiac; D. O'Connell; V. A. Kadetov; U. Czarnetzki; T. Schwarz-Selinger; H. Halfmann; P. Awakowicz

2005-01-01

37

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

E-print Network

Atmospheric Pressure Humid Argon DBD Plasma for the Application of Sterilization - Measurement peroxide have been measured downstream of an atmospheric pressure humid argon dielectric barrier discharge, sterilization I. INTRODUCTION Non-thermal plasma technology at atmospheric pressure using oxygen

Paris-Sud XI, Université de

38

Chlorine Dioxide Gas Sterilization under Square-Wave Conditions  

PubMed Central

Experiments were designed to study chlorine dioxide (CD) gas sterilization under square-wave conditions. By using controlled humidity, gas concentration, and temperature at atmospheric pressure, standard biological indicators (BIs) and spore disks of environmental isolates were exposed to CD gas. The sporicidal activity of CD gas was found to be concentration dependent. Prehumidification enhanced the CD activity. The D values (time required for 90% inactivation) of Bacillus subtilis subsp. niger ATCC 9372 BIs were estimated to be 1.5, 2.5, and 4.2 min when exposed to CD concentrations of 30, 15, and 7 mg/liter, respectively, at 23°C and ambient (20 to 40%) relative humidity (RH). Survivor tailings were observed. Prehumidification of BIs to 70 to 75% RH in an environmental chamber for 30 min resulted in a D value of 1.6 min after exposure to a concentration of 6 to 7 mg of CD per liter at 23°C and eliminated survivor tailing. Prolonging prehumidification at 70 to 75% RH for up to 16 h did not further improve the inactivation rate. Prehumidification by ultrasonic nebulization was found to be more effective than prehumidification in the environmental chamber, improving the D value to 0.55 min at a CD concentration of 6 to 7 mg/liter. Based on the current observations, CD gas is estimated, on a molar concentration basis, to be 1,075 times more potent than ethylene oxide as a sterilant at 30°C. A comparative study showed B. subtilis var. niger BIs were more resistant than other types of BIs and most of the tested bacterial spores of environmental isolates. PMID:16348127

Jeng, David K.; Woodworth, Archie G.

1990-01-01

39

[Dependency of a microbiological test of a formaldehyde gas sterilization procedure on the shape of objects to be sterilized].  

PubMed

During the last decade, a number of procedures have been developed by different firms for the sterilization of heat-sensitive instruments using a mixture of formaldehyde and water vapor at a temperature of approximately 60 degrees C as means of sterilization. Instruments to be sterilized by this technique as e.g. sounds and catheters normally have long narrow cavities. Therefore, the formaldehyde gas sterilization procedures have to be tested primarily for their capability of achieving a sufficient microbicidal effect within those cavities. For this purpose, the bioindicators are placed into special test pieces. The test pieces commonly in use differ widely in their construction, shape, and size. They mostly consist of some hollow cylinder with an attached capillary or a tube (see Table 1). The authors demonstrated by means of models that the variety of test pieces in use meant that the sterilization procedures had to meet quite different requirements. The models consisted of flexible tubes differing in diameter and length and were connected to short glass tubes. These glass tubes having identical or wider inner diameters than the flexible tubes served as receptacles containing the bioindicators. Spores of Bacillus stearothermophilus served as test organisms. The spores were suspended in defibrinated sheep blood and dried on filter paper. The efficiency of the sterilization technique was measured in terms of the relative number of indicator strips with surviving germs (i.e. non-sterilized indicators) after treatment of the test pieces with the formaldehyde gas. At first, the test results were examined as to their dependency on the length of the flexible tubes. These tubes were 3 mm wide and 5 to 100 cm long, each being sealed at one end and with the bioindicators placed near the sealed end. The percentage of indicators with surviving germs increased with the length of the tubes. After the sterilization process, nearly all indicators (92%) contained in the 1 m tubes proved to be non-sterile (see Table 2). The same results were obtained with tubes open at both ends, with the bioindicators located in the middle section of the tubes (see Table 3). Using tubes of 1 m length, the dependency of the test results on the inner diameter of the test pieces was demonstrated. While all indicators placed into tubes of 3 mm inner diameter still contained surviving germs, those in the tubes of 9 mm inner diameter were all sterile (see Table 4).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6367309

Spicher, G; Borchers, U

1983-06-01

40

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

NASA Astrophysics Data System (ADS)

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

Kylián, O.; Sasaki, T.; Rossi, F.

2006-05-01

41

Inductively-Coupled RF Powered O2 Plasma as a Sterilization Source  

NASA Technical Reports Server (NTRS)

Low-temperature or cold plasmas have been shown to be effective for the sterilization of sensitive medical devices and electronic equipment. Low-temperature plasma sterilization procedures possess certain advantages over other protocols such as ethylene oxide, gamma radiation, and heat due to the use of inexpensive reagents, the insignificant environmental impacts and the low energy requirements. In addition, plasmas may also be more efficacious in the removal of robust microorganisms due to their higher chemical reactivity. Together, these attributes render cold plasma sterilization as ideal for the surface decontamination requirements for NASA Planetary Protection. Hence, the work described in this study involves the construction, characterization, and application of an inductively-coupled, RF powered oxygen (O2) plasma.

Sharma, S. P.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Mogul, R.; Khare, B.; Chan, S. L.; Arnold, James O. (Technical Monitor)

2001-01-01

42

Sterilization of contaminated matter with an atmospheric pressure plasma  

Microsoft Academic Search

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

Mounir Laroussi

1996-01-01

43

Gas lens laser produced plasma.  

PubMed

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

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

1989-07-01

44

Plasma sterilization using glow discharge at atmospheric pressure  

Microsoft Academic Search

Recent development of atmospheric pressure glow discharge was compared with the performance of an apparatus used in the first APG experiment, in terms of sterilization of newly classified biological indicator: Bacillus atrophaeus, former Bacillus subtilis var. niger and Geobacillus stearothermophilus. Stabilization was attained by controlling the experimental conditions, at low frequency: 100 kHz and Radio Frequency: 13.56 MHz, water vapor\\/He

Tetsuya Akitsu; Hiroshi Ohkawa; Masao Tsuji; Hideo Kimura; Masuhiro Kogoma

2005-01-01

45

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

46

Comparative sterilization effectiveness of plasma in O2-H2O2 mixtures and ethylene oxide treatment.  

PubMed

We investigated the influence of variable parameters of plasma sterilization and compared its effectiveness with that of ethylene oxide using a reactive ion etching plasma reactor at 13.56 MHz. Gases tested were pure oxygen and oxygen-hydrogen peroxide mixtures in 190/10, 180/20, and 160/40 sccm ratios with constant gas flow at 200 sccm, pressure at 0.100 torr, radio-frequency power at 25 W, 50 W, 100 W, and 150 W, and temperature below 60 degrees C. Ethylene oxide sterilization was performed using 450 mg/L at 55 degrees C, 60% humidity, and -0.65 and 0.60 kgf/cm2 pressure. The biological indicator was Bacillus atrophaeus ATCC 9372, with exposure times of 3 to 120 min. Observed D values were 215.91, 55.55, 9.19, and 2.98 min for pure oxygen plasma at 25 W, 50 W, 100 W, and 150 W, respectively. Oxygen-hydrogen peroxide plasma produced D values of 6.41 min (190/10), 6.47 min (180/20), and 4.02 min (160/40) at 100 W and 1.47 min (190/10), 3.11 min (180/20), and 1.94 min (160/40) at 150 W. Ethylene oxide processes resulted in a D value of 2.86 min. Scanning electron microscopy analyses showed damage to the spore cortex. PMID:17722487

Silva, J M F; Moreira, A J; Oliveira, D C; Bonato, C B; Mansano, R D; Pinto, T J A

2007-01-01

47

Analysis of emission data from O2 plasmas used for microbe sterilization  

Microsoft Academic Search

In order to study the sterilization capabilities of radio frequency driven low pressure oxygen plasmas, the radiative emission was recorded at various pressures and input powers. A distinct transition from the bright mode (primarily inductively coupled) to a dim mode (primarily capacitively coupled) was observed as the pressure was increased and\\/or the power decreased. The data was further analyzed to

S. P. Sharma; B. A. Cruden; M. V. V. S. Rao; A. A. Bolshakov

2004-01-01

48

A gas monitoring system for ethylene oxide sterilizers with constant sample flow through a microwave cavity spectrometer.  

PubMed

This paper reports a measurement system for monitoring the gas concentrations of ethylene oxide (EO) within sterilizers. It samples gas from the sterilizer chamber at a constant flow into a microwave cavity spectrometer. The pressure in the cavity of the spectrometer is linearly proportional to that in the sterilizer chamber, hence the partial pressure (i.e. gas concentration) of the EO gas is linearly proportional to that in the chamber. Measurement of the gas concentration in the chamber can therefore take place without the need to monitor and interpret the chamber pressure. As a consequence the reliability of the sterilization process may be improved, thus enabling a reduction in the in-chamber concentration of EO during sterilization and, hence, EO residues. The microwave cavity spectrometer operates under conditions of power saturation, and there is a good linear correlation between the output signal and the concentration of EO in the gas cell (to within a standard error of 4%). PMID:8295225

Zhu, Z; Gibson, C; Samuel, A H; Matthews, L P

1993-01-01

49

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

50

Characterization of stationary and pulsed inductively coupled RF discharges for plasma sterilization  

NASA Astrophysics Data System (ADS)

Sterilization of bio-medical materials using radio frequency (RF) excited inductively coupled plasmas (ICPs) has been investigated. A double ICP has been developed and studied for homogenous treatment of three-dimensional objects. Sterilization is achieved through a combination of ultraviolet light, ion bombardment and radical treatment. For temperature sensitive materials, the process temperature is a crucial parameter. Pulsing of the plasma reduces the time average heat strain and also provides additional control of the various sterilization mechanisms. Certain aspects of pulsed plasmas are, however, not yet fully understood. Phase resolved optical emission spectroscopy and time resolved ion energy analysis illustrate that a pulsed ICP ignites capacitively before reaching a stable inductive mode. Time resolved investigations of the post-discharge, after switching off the RF power, show that the plasma boundary sheath in front of a substrate does not fully collapse for the case of hydrogen discharges. This is explained by electron heating through super-elastic collisions with vibrationally excited hydrogen molecules.

Gans, T.; Osiac, M.; O'Connell, D.; Kadetov, V. A.; Czarnetzki, U.; Schwarz-Selinger, T.; Halfmann, H.; Awakowicz, P.

2005-05-01

51

Non-thermal plasma applications in air sterilization  

Microsoft Academic Search

Summary form only given. In our present study, we are constructing a physiochemical model of the oxidizing effects of the active chemical species generated by non-thermal atmospheric pressure plasma on the influenza A virus. The results of our model provides us with an estimate of the optimal dose of active species required to destroy varying concentrations of airborne influenza viruses.

Michael J. Gallagher; Alexander Gutsol; A. Fridman; G. Friedman; A. Dolgopolsky

2004-01-01

52

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. PMID:23792697

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

2013-01-01

53

Discharge conditions for CW and pulse-modulated surface-wave plasmas in low-temperature sterilization  

NASA Astrophysics Data System (ADS)

The discharge conditions required for low-temperature plasma sterilization were investigated using low-pressure surface-wave plasma (SWP). The discharge conditions for both continuous wave (CW) and pulse-modulated SWPs in low-temperature sterilization of Geobacillus stearothermophilus with a population of 1.5 × 106 and 3.0 × 106 were studied by varying the microwave input power from 500 W to 3 kW, and the effective plasma treatment time from 40 to 300 s. Results showed that sterilization was possible in a shorter treatment time using a higher microwave power for both CW and pulse-modulated SWPs. Pulse-modulated SWPs gave effective sterilization at a temperature roughly 10 to 20 °C below that of CW SWPs under the same average microwave power.

Xu, L.; Terashita, F.; Nonaka, H.; Ogino, A.; Nagata, T.; Koide, Y.; Nanko, S.; Kurawaki, I.; Nagatsu, M.

2006-01-01

54

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

SciTech Connect

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

Wang Dacheng [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Zhao Di [Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Photoelectrical Engineering, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Feng Kecheng [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Zhang Xianhui [Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu Dongping [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022 (China); Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Yang Size [Department of Aeronautics, Fujian Key Laboratory for Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

2011-04-18

55

Diagnostics and active species formation in an atmospheric pressure helium sterilization plasma source  

NASA Astrophysics Data System (ADS)

Systematic spectroscopic studies and diagnostics of an atmospheric pressure radiofrequency (13.56 MHz) He plasma is presented. The discharge is an intrinsic part of the resonant circuit of the radiofrequency oscillator and was obtained using a monoelectrode type torch, at various gas flow-rates (0.1-6.0 l/min) and power levels (0-2 W). As function of He flow-rate and power the discharge has three developing stages: point-like plasma, spherical plasma and ellipsoidal plasma. The emission spectra of the plasma were recorded and investigated as function of developing stages, flow-rates and plasma power. The most important atomic and molecular components were identified and their evolution was studied as function of He flow-rate and plasma power towards understanding basic mechanisms occurring in this type of plasma. The characteristic temperatures (vibrational Tvibr, rotational Trot and excitation Texc) and the electron number density ( n e) were determined.

Simon, A.; Anghel, S. D.; Papiu, M.; Dinu, O.

2009-01-01

56

Whistleron gas in magnetized plasmas  

SciTech Connect

The nonlinear dynamics of whistler waves in magnetized plasmas is studied. Since the plasmas and beam-plasma systems considered here are assumed to be weakly collisional, the point of reference for the analysis performed in the present paper is the system of hydrodynamic and field equations. The renormalization group method is applied to obtain dynamical equations for the slowly varying amplitudes of whistler waves. Further, it has been shown that the amplitudes of eigenmodes satisfy an infinite system of coupled nonlinear Schroedinger equations. In this sense, the whistler eigenmodes form a sort of a gas of interacting quasiparticles, while the slowly varying amplitudes can be considered as dynamical variables heralding the relevant information about the system. An important feature of the approach is that whistler waves do not perturb the initial uniform density of plasma electrons. The plasma response to the induced whistler waves consists in velocity redistribution which follows exactly the behavior of the whistlers. In addition, selection rules governing the nonlinear mode coupling have been derived, which represent another interesting peculiarity of the description presented here.

De Martino, Salvatore; Falanga, Mariarosaria; Tzenov, Stephan I. [Dipartimento di Fisica E.R. Caianiello, Universita degli Studi di Salerno, Via S. Allende, I-84081 Baronissi (Saudi Arabia) (Italy) and INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, I-84081 Baronissi (SA) (Italy)

2005-07-15

57

Analysis of emission data from O2 plasmas used for microbe sterilization  

NASA Astrophysics Data System (ADS)

In order to study the sterilization capabilities of radio frequency driven low pressure oxygen plasmas, the radiative emission was recorded at various pressures and input powers. A distinct transition from the bright mode (primarily inductively coupled) to a dim mode (primarily capacitively coupled) was observed as the pressure was increased and/or the power decreased. The data was further analyzed to estimate the electron temperature, rotational and vibrational temperatures, and various species concentrations. Based on the diffusion and rovibrational relaxation times, it is concluded that the rotational temperatures can be assumed to be in equilibrium with the translational temperature. The ions are produced "hot" and have little time to get equilibrated with the translational temperature. It is further determined that in the bright mode, which is more effective in microbe sterilization, the translational/rotational temperatures are in the 650-850 K range, the electron temperatures are low (3.5-4.5 eV), and the concentrations of atomic O and atomic metastables are at 1 order of magnitude higher than in the dim mode.

Sharma, S. P.; Cruden, B. A.; Rao, M. V. V. S.; Bolshakov, A. A.

2004-04-01

58

Nonequilibrium EEDF in gas discharge plasmas  

Microsoft Academic Search

Nonequilibrium effects associated with spatial and temporal nonlocality between electron energy distribution and electromagnetic field in gas discharge plasmas at low gas pressures are reviewed in this paper. Formation of nonequilibrium EEDF is discussed for capacitive and inductive radio-frequency discharges. The possibility of electron temperature control is considered for gas discharge plasmas at nonequilibrium condition

Valery A. Godyak; Osram Sylvania

2006-01-01

59

Feasibility study of the sterilization of pork and human skin surfaces by atmospheric pressure plasmas  

Microsoft Academic Search

Atmospheric pressure radio frequency (rf) glow discharge characteristics were studied aiming for the plasma treatment of living tissues such as pork and human skin. Electrical and optical measurements of the plasma gave reasonable values at low current of 4 mA and gas temperature of 60 °C at 100 W. The colorimetric measurement of the treated pork sample demonstrated negligible thermal effect from the

Se Youn Moon; D. B. Kim; B. Gweon; W. Choe; H. P. Song; Cheorun Jo

2009-01-01

60

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

PubMed

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

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

2009-06-01

61

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

E-print Network

, the power used and the speed of killing vegetative cells. The surface temperature during plasma generation States of America, 2 Department of Pathology, Immunology and Laboratory Medicine, College of Medicine and Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America

Roy, Subrata

62

[Dependence of microbiologic test results of formaldehyde gas sterilization methods on the nature of the test material].  

PubMed

The efficiency of a formaldehyde gas sterilization procedure was evaluated with the aid of test pieces consisting of various materials. Both rigid and flexible tubes served as test pieces. The tubes were 75 cm long with an inner diameter of 1 mm and were sealed at one end. The bioindicators were placed inside the tubes close to the sealed end. Dried spores of Bacillus stearothermophilus adhering to linen threads served as test organisms. The test results varied according to the material of the test pieces and the thickness of their walls (see Table 1). In flexible tubes made of silicon rubber, all bioindicators became sterile, in tubes of stainless steel, all bioindicators exhibited test organisms that had survived. The findings for materials such as polyvinyl chloride, polyethylene, polyamide and polytetrafluorethylene ranged between these two extremes; the frequencies of bioindicators containing viable germs were 10, 55, 68 and 85%, respectively. Rigid and flexible tubes which had been sealed at both ends served to demonstrate that silicon rubber and polyvinyl chloride were highly permeable for formaldehyde and water vapour. Also the other plastic materials tested were permeable for formaldehyde and water vapour but longer exposure periods were needed to create conditions in the interior of the tubes that would result in a killing of the test organisms (see Fig 2). In this respect, polyamide exhibited a peculiar behaviour. The number of viable spores remained at the initial level for a long period before a decline took place. From the results of testing, it is concluded that test pieces must conform to the objects to be sterilized not only in their dimensions (length, inner diameter) but also in the characteristics of their material. The walls of the test pieces should not have a higher permeability for formaldehyde and water vapour than the material to be sterilized. The highest demands on the efficiency of formaldehyde gas sterilization procedures are those created by mental tubes and thick-walled flexible polytetrafluorethylene. Instruments and devices to be sterilized by a formaldehyde gas procedure should be preferentially made of materials which are sufficiently permeable for formaldehyde and water vapour as e.g. silicon rubber. Such gas-permeable components may considerably facilitate the sterilization of cavities which have a small lumen and are difficult to reach. PMID:3113100

Spicher, G; Borchers, U

1987-05-01

63

Application of Plasma on Reentry Vehicle Communication and Interplanetary Spacecraft Sterilization  

NASA Astrophysics Data System (ADS)

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

Fenstermacher, Jarrod J.

64

Postpartum Sterilization  

MedlinePLUS

... of a baby. What is the most common method of postpartum sterilization? The method used most often ... is postpartum sterilization? • What is the most common method of postpartum sterilization? • When is postpartum sterilization performed? • ...

65

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

66

Protein modification caused by a high dose of gamma irradiation in cryo-sterilized plasma: protective effects of ascorbate.  

PubMed

Gamma irradiation is a method of pathogen inactivation in plasma derivatives currently under development. Gamma rays inactivate all known blood-borne viruses. However, the virucidally effective dose of radiation may affect the integrity and function of plasma proteins. Biological activity recoveries of the therapeutic products were shown to be significantly improved by lowering the irradiation temperature and by the addition of antioxidants; the mechanisms responsible for this have not been elucidated yet. Here we sterilized human plasma by gamma irradiation (50 kGy), on dry ice, in the presence (or absence) of ascorbate. The subsequent protein oxidation was quantified by a ferric-xylenol orange (hydroperoxides) and by DNPH-coupled assays (carbonyls). We demonstrated for the first time that irradiation of frozen plasma (without saturation with oxygen) resulted in the generation of protein hydroperoxides, the yield of which was dramatically decreased when plasma was irradiated in the presence of either sodium azide or ascorbate. In irradiated plasma the concentration of protein carbonyls was twofold higher than in nonirradiated control. Ascorbate significantly inhibited protein carbonylation. We concluded that freezing of plasma during irradiation does not provide the complete protection against protein carbonylation and hydroperoxide generation. Addition of ascorbate and some nontoxic metabolic inhibitors might be useful as protecting stabilizers. PMID:16443169

Zbikowska, Halina M; Nowak, Pawel; Wachowicz, Barbara

2006-02-01

67

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

68

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

2011-12-01

69

Spacecraft sterilization.  

NASA Technical Reports Server (NTRS)

Spacecraft sterilization is a vital factor in projects for the successful biological exploration of other planets. The microorganisms of major concern are the fungi and bacteria. Sterilization procedures are oriented toward the destruction of bacterial spores. Gaseous sterilants are examined, giving attention to formaldehyde, beta-propiolactone, ethylene oxide, and the chemistry of the bactericidal action of sterilants. Radiation has been seriously considered as another method for spacecraft sterilization. Dry heat sterilization is discussed together with the effects of ethylene oxide decontamination and dry heat sterilization on materials.

Kalfayan, S. H.

1972-01-01

70

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

Microsoft Academic Search

This paper reports that a new plasma generator at atmospheric pressure, which is composed of two homocentric cylindrical all-metal tubes, successfully generates a cold plasma jet. The inside tube electrode is connected to ground, the outside tube electrode is connected to a high-voltage power supply, and a dielectric layer is covered on the outside tube electrode. When the reactor is

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

2006-01-01

71

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

72

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

73

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

Microsoft Academic Search

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

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

2007-01-01

74

Reversible Sterilization  

ERIC Educational Resources Information Center

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

Largey, Gale

1977-01-01

75

Sterile neutrinos?  

E-print Network

The notion of sterile neutrinos is discussed. The schemes of mixing of four massive neutrinos, which imply the existence of sterile neutrinos, are briefly considered. Several model independent methods that allow to reveal possible transitions of solar neutrinos into sterile states are presented.

S. M. Bilenky; C. Giunti

1999-05-05

76

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

77

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

78

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

79

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

80

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

81

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

82

Sterilization of space hardware.  

NASA Technical Reports Server (NTRS)

Discussion of various techniques of sterilization of space flight hardware using either destructive heating or the action of chemicals. Factors considered in the dry-heat destruction of microorganisms include the effects of microbial water content, temperature, the physicochemical properties of the microorganism and adjacent support, and nature of the surrounding gas atmosphere. Dry-heat destruction rates of microorganisms on the surface, between mated surface areas, or buried in the solid material of space vehicle hardware are reviewed, along with alternative dry-heat sterilization cycles, thermodynamic considerations, and considerations of final sterilization-process design. Discussed sterilization chemicals include ethylene oxide, formaldehyde, methyl bromide, dimethyl sulfoxide, peracetic acid, and beta-propiolactone.

Pflug, I. J.

1971-01-01

83

Dusty Plasma Structures in Gas Mixtures  

SciTech Connect

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

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

2008-09-07

84

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

SciTech Connect

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

Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)] [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)

2014-04-15

85

New disinfection and sterilization methods.  

PubMed Central

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

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

2001-01-01

86

Plasma catalytic hybrid processes: gas discharge initiation and plasma activation of catalytic processes  

Microsoft Academic Search

Catalytic reactions of a gas mixture can efficiently be induced by pre-treatment using a gas discharge plasma or by combined treatment in a plasma catalytic hybrid reactor. The effects of plasma treatment can be excitation of molecules, formation of short lived radicals, formation of long lived intermediate species, emission of UV-radiation, or simply gas heating.By dielectric barrier discharge (DBD) pre-treatment

Th. Hammer; Th. Kappes; M. Baldauf

2004-01-01

87

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

PubMed

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

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

2005-08-01

88

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

89

Shroud gas effects on plasma characteristics of thermal plasma jets at atmospheric conditions  

Microsoft Academic Search

Summary form only given. High-enthalpy and high-speed plasma flames ejected from nontransferred dc plasma torches have been widely used for material processings such as plasma spray coating and plasma synthesis. The plasma flow is produced by the arc-gas interactions between the cathode and anode inside the torch and expands as a jet through the nozzle into the air in the

K. D. Kang; B. L. Choi; S. H. Hong

1996-01-01

90

Shroud gas effects on plasma characteristics of thermal plasma jets at atmospheric conditions  

SciTech Connect

High-enthalpy and high speed plasma flames ejected from nontransferred dc plasma torches have been widely used for material processings such as plasma spray coating and plasma synthesis. The plasma flow is produced by the arc-gas interactions between the cathode and anode inside the torch and expands as a jet through the nozzle into the air in the case of atmospheric conditions. The entrainment of surrounding air into the plasma flame, which reduces the quality of materials processed, is undesirable for the efficient material processings. This can be avoided by generating the plasma jets in the low pressure environment or by flowing the shroud gas around the jet flame. The torch operation with the shroud gas is simpler and more economic than the case of low pressure environment. In this work, shroud gas effects on the plasma flow at atmospheric conditions are investigated by a numerical analysis for finding the mole fraction of entrained air and the distributions of temperature and velocity components of plasma jets. The calculated results of temperature and velocity fields indicate that the plasma flame becomes longer and somewhat wider in the tail of the flame due to the less entrainment of air and the mixing of the swirling shroud gas with the plasma gas.

Kang, K.D.; Choi, B.L.; Hong, S.H. [Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering

1996-12-31

91

Potential Structure Formation in the Gas-Liquid Interfacial Plasmas  

NASA Astrophysics Data System (ADS)

Specific kinds of plasmas composed of ionic liquids and gas phase discharge plasmas are created. These novel gas-liquid interfacial plasmas could contribute to the effective creation and modification of nano-bio materials, where the control of ion behavior in both the gas and liquid phases is desired. In this study, the plasma source containing the ionic liquids is developed for clarifying the effects of the ionic liquids on the plasma generation and the potential structure formed in the gas-liquid interfacial region is investigated for controlling the ion motion A direct current (DC) or a pulsed DC discharge plasma is generated just above the ionic liquid by applying the DC or the pulsed DC voltage to an electrode immersed in the ionic liquid against a grounded electrode set in the gas phase region. The precise potential structure between these electrodes through the gas-liquid interfacial region is clarified, and the dynamics of the plasma ions is found to be controlled using the sheath electric field in the interfacial region. The control of the plasma ion irradiation flux and energy to the ionic liquid leads to the creation of various kinds of nanoparticles.

Kaneko, Toshiro; Harada, Takashi; Chen, Qiang; Hatakeyama, Rikizo

2009-11-01

92

Sterilization by Laparoscopy  

MedlinePLUS

What is sterilization? Sterilization is a permanent method of birth control. It is the most popular form of birth control worldwide. What is the sterilization procedure for women? Tubal sterilization is sterilization for ...

93

A microfluidic chip for generating reactive plasma at gas–gas interface formed in laminar flow  

NASA Astrophysics Data System (ADS)

A gas–gas interface is used for generating a localized reactive plasma flow at an atmospheric pressure. A microfluidic chip is fabricated as the reactor integrating a small plasma source located upstream. Within a Y-shaped microchannel, a discharging gas flows with a chemical gas. Owing to the small width of the microchannel, the gas flow is stabilized in a laminar flow. The resultant gas–gas interface is formed in the area where two gases flow facing each other activating the chemical gas through the energetic species in the discharging gas. A characteristic stream pattern is observed as the etching profile of a carbon film with a sub-µm sharp step change that can be explained by the spatial distribution of the reactive oxygen. This etching profile is different from that obtained when plasma discharging occurs near the channel exit being affected by the turbulent flow.

Hashimoto, Masahiro; Tsukasaki, Katsuki; Kumagai, Shinya; Sasaki, Minoru

2015-01-01

94

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

95

Postpartum Sterilization  

MedlinePLUS

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

96

Spatial relaxation of electrons in inert and molecular gas plasmas  

SciTech Connect

The electron kinetics in spatially inhomogeneous plasma regions is a subject of growing interest with respect to the microscopic treatment of real discharge plasmas. In order to improve the understanding of the complex electron behaviour in inhomogeneous plasma regions an efficient approach for solving the one-dimensional inhomogeneous electron Boltzmann equation in weakly ionized, collision dominated plasmas has been recently developed. The kinetic equation includes elastic and inelastic collisions of electrons and the action of an inhomogeneous electric field. This method is used to investigate now the relaxation of the electrons to homogeneous states in different inert and molecular gas plasmas under the action of various constant electric fields.

Sigeneger, F.; Winkler, R. [Institut fuer Niedertemperatur-Plasmaphysik, Greifswald (Germany)

1995-12-31

97

Modeling of Induction Plasma Process for Fullerene Synthesis: Effect of Plasma Gas Composition and Operating Pressure  

Microsoft Academic Search

A mathematical model has been developed on the continuous synthesis of fullerenes by direct evaporation of carbon-containing\\u000a materials using induction thermal plasma technology. The main purpose of this study is to numerically investigate the effect\\u000a of plasma gas composition and operating pressure on the fullerene formation. The simulation results confirmed that Ar–He mixture\\u000a plasma is more efficient than argon plasma

K. S. KimA; A. Moradian; J. Mostaghimi; Gervais Soucy

2010-01-01

98

Pulse plasma carburizing and high pressure gas quenching -- Industrial applications  

SciTech Connect

Pulse plasma carburizing with high pressure gas quenching up to 20 bar is the newly developed case hardening process now available in production size equipment. The first part of results demonstrates the tremendous potential of high pressure gas quenching for successful hardening of case hardening steels. The second part opens a window to glance at the pulse plasma carburizing of complex shaped parts. Both processes improve economical data and performance of carburizing processes.

Preisser, F.; Schnatbaum, F. [ALD Vacuum Technologies GmbH, Erlensee (Germany)

1995-12-31

99

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

100

NUCLEAR GENERATED PLASMAS IN NOBLE GAS THERMIONIC CONVERTERS  

Microsoft Academic Search

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

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

1963-01-01

101

Effect of Gas Mixture on Plasma Jet Discharge Morphology  

Microsoft Academic Search

The morphology of plasma emission from a stream- erlike atmospheric pressure plasma jet initiated inside a glass capillary has been measured with a high spatial resolution for a gas flow of pure helium and He with a 5% Ar admixture using 5-ns time-gated intensified charge-coupled device imaging. In the pure helium plasma jet, emission remains annular and converges gradually along

Robert J. Leiweke; Brian L. Sands; Biswa N. Ganguly

2011-01-01

102

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

103

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

NASA Astrophysics Data System (ADS)

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

Cooper, C. M.; Gekelman, W.

2013-06-01

104

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

105

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

PubMed

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

Spicher, G; Borchers, U

1984-10-01

106

SIMPLODE: An imploding gas puff plasma model. 1. Neon  

NASA Astrophysics Data System (ADS)

A non-LTE dynamic pinch model - SIMPLODE - has been developed and applied to describing the implosion dynamics of a K-shell radiating gas puff. Numerical simulations have been carried out with neon gas puffs and compared with recent experimental results obtained on GAMBLE II. In addition, the influence of the Plasma Erosion Opening Switch on the K-shell yield is investigated.

Davis, J.; Agritellis, C.; Duston, D.

1985-07-01

107

EDITORIAL: Gas plasmas in biology and medicine  

Microsoft Academic Search

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

Eva Stoffels

2006-01-01

108

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

109

[Low-temperature sterilization for the surgical infection prophylaxis].  

PubMed

The comparative characteristic of the accepted methods of low-temperature sterilization of medical equipment is given. Special attention is devoted to the surgical infection prophylaxis. The efficacy, expediency and safety of gas sterilization with ethilenoxide is proved. Plasmic methods of sterilization is recommended for use together with other methods of low-temperature sterilization. PMID:21716218

Kornev, I I; Baranov, G A; Ul'ianov, V I

2011-01-01

110

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. PMID:21566796

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

2011-01-01

111

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

112

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

113

Development of air micro plasma source using a magnetic loop with operation at modulated ultra high frequencies  

Microsoft Academic Search

Summary form only given. Micro plasma sources are a rapidly growing area of study in plasma sciences, attracting widespread attention due to the large number of possible applications such as biomedical sterilizers, plasma displays, and chemical analyzers. The micro plasma operating power, gas, and pressure are three main issues to address in order to make portable micro plasma devices.We report

M. Taghioskoui; J. Perlow; M. Zaghloul

2010-01-01

114

Comparative study of different techniques for the sterilization of poly-L-lactide electrospun microfibers: effectiveness vs. material degradation.  

PubMed

Electrospinning of biopolymeric scaffolds is a new and effective approach for creating replacement tissues to repair defects and/or damaged tissues with direct clinical application. However, many hurdles and technical concerns regarding biological issues, such as cell retention and the ability to grow, still need to be overcome to gain full access to the clinical arena. Interaction with the host human tissues, immunogenicity, pathogen transmission as well as production costs, technical expertise, and good manufacturing and laboratory practice requirements call for careful consideration when aiming at the production of a material that is available off-the-shelf, to be used immediately in operative settings. The issue of sterilization is one of the most important steps for the clinical application of these scaffolds. Nevertheless, relatively few studies have been performed to systematically investigate how sterilization treatments may affect the properties of electrospun polymers for tissue engineering. This paper presents the results of a comparative study of different sterilization techniques applied to an electrospun poly-L-lactide scaffold: soaking in absolute ethanol, dry oven and autoclave treatments, UV irradiation, and hydrogen peroxide gas plasma treatment. Morphological and chemical characterization was coupled with microbiological sterility assay to validate the examined sterilization techniques in terms of effectiveness and modifications to the scaffold. The results of this study reveal that UV irradiation and hydrogen peroxide gas plasma are the most effective sterilization techniques, as they ensure sterility of the electrospun scaffolds without affecting their chemical and morphological features. PMID:20306434

Rainer, Alberto; Centola, Matteo; Spadaccio, Cristiano; Gherardi, Giovanni; Genovese, Jorge A; Licoccia, Silvia; Trombetta, Marcella

2010-02-01

115

Hybrid simulation of neutral gas interacting with a plasma  

NASA Astrophysics Data System (ADS)

Plasma in contact with a material surface is neutralized and recycled as a gas that in turn interacts with the plasma. The neutral gas may be in a kinetic regime (long mean free path) in some regions and in a fluid regime (short mean free path) elsewhere. In order to model this situation, we imagine the neutral gas as the superposition of two populations, one fluid and one kinetic, with transfer terms coupling the two populations. We model these populations by coupling together a plasma fluid code, B2.5,(B. J. Braams, Radiative Divertor Modelling for ITER and TPX, Contrib. Plasma Phys. 36), 276-281 (1996) and a neutral Monte Carlo code, Degas 2.footnote D. P. Stotler and C. F. F. Karney, Neutral Gas Transport Modeling with Degas 2, Contrib. Plasma Phys. 34, 392-397 (1994). The coupling terms conserve mass, momentum, and energy, and are chosen so that fluid neutrals are converted to kinetic neutrals where their mean free path is long and vice versa. In this scheme, self collisions are never a dominant term in the Monte Carlo code may be treated by a simplified BGK model.

Karney, C. F. F.; Stotler, D. P.; Braams, B. J.

1997-08-01

116

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

117

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

118

Observations on a formaldehyde low-temperature steam sterilizer.  

PubMed

In Finnish hospitals, heat labile equipment is mostly sterilized by ethylene oxide (EO) gas. Formaldehyde sterilizers are rarely used. We have tested a new commercial autoclave constructed exclusively for formaldehyde and low-temperature steam (F-LTS) sterilization, offering a potentially safer and cheaper method of sterilization. Both the sterilizing efficacy of the apparatus and the levels of formaldehyde in the processed materials were studied. PMID:10285026

Kuronen, T

1987-10-01

119

Sterilization and care of surgical instruments and supplies.  

PubMed

Adequate instrument handling and sterilization are important aspects of office surgery. Heat sterilization is the most reliable choice. The steam autoclave is highly recommended. Dry heat is effective but can pose some storage problems. Gas sterilization is useful for heat-sensitive materials but not practical for the private office. Cold "sterilization" is not reliable for incisional surgery. In addition to proper sterilization modality selection, the surgeon must observe important standards of instrument care, packing, and storage. PMID:6480947

Sebben, J E

1984-09-01

120

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

121

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

122

Non-Equilibrium EEDF in Gas Discharge Plasmas Osram Sylvania  

E-print Network

Jersey August 2-4 2005 #12;Electron Temperature in gas Discharge (Uniform electric field, Maxwellian EEDF sheath or skin layer) Led to cool down of main body of electrons in adjacent plasma. This occurs only has features of a non-self-sustained discharge with typically low electron temperature #12;Heating

Kaganovich, Igor

123

Mathematical model of gas plasma applied to chronic wounds  

SciTech Connect

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

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

2013-11-15

124

Mathematical model of gas plasma applied to chronic wounds  

NASA Astrophysics Data System (ADS)

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

Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P.; Zhang, Y. T.

2013-11-01

125

Application of non-thermal plasma on gas cleansing  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

126

Haemostatic properties of human plasma subjected to a sterilizing dose of gamma irradiation in the presence of ascorbate.  

PubMed

The objective was to study the effects of gamma irradiation, in the presence of sodium ascorbate, on coagulation/fibrinolytic activity of fresh frozen plasma to be applied to inactivate the transfusion-transmitted viruses in plasma-derived products. Plasma was irradiated (50 kGy total dose, on dry ice) using a 60Co source. The plasma proteins were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and western blot and the following parameters estimated: prothrombin time, functional fibrinogen concentration, thrombin-induced fibrinogen polymerization, plasminogen activity, and tissue-type plasminogen activator-induced conversion of plasminogen to plasmin. In irradiated plasma a moderate fragmentation of the most labile plasma proteins was found. The prothrombin time was prolonged (1.5-fold), functional fibrinogen was significantly reduced (60%), fibrinogen polymerization was impaired, plasminogen was predominantly maintained (90%) and tissue-type plasminogen activator-induced conversion of plasminogen to plasmin was unchanged. Ascorbate (25 mmol/l) raised the level of functional fibrinogen in irradiated plasma (to 50%; P=0.0245) and slightly accelerated its polymerization. The small protective effect of ascorbate might be due to inhibition of the radiation-induced fibrinogen oxidation and/or fragmentation but addition of other antioxidants/stabilizers would be crucial when a high irradiation dose, an effective treatment for inactivation of the most resistant viruses, is applied. PMID:17413765

Zbikowska, Halina Malgorzata; Nowak, Pawel; Wachowicz, Barbara

2007-04-01

127

Wound healing modeling: investigating ambient gas plasma treatment efficacy  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

128

[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

129

Instability suppression by a gas jet in plasma focus devices  

NASA Astrophysics Data System (ADS)

The density of the filling gas in dense plasma foci is limited by the energy available for breakdown, and ionization of the neutral gas by the plasma sheath, during the rundown phase. On the other hand, it is desirable to increase the density of the plasma during the compression phase, when the current approaches its maximum, in order to improve the neutron yield. It has been shown both in samll [1] and large [2] plasma foci that, by the injection of a gas jet from the tip of the inner electrode, it is possible to decouple the compression phase from the breakdown and the rundown phases. Not only the neutron emission is significantly increased, but the uniformity of the discharges is also improved. Since the wide variability in the radiation of these kind of devices is strongly related to the m=0 instabilities during the compression phase, it has been speculated that the jet is able to suppress them. The purpose of this work is to study the conditions under which an axial jet could be able to suppress the instabilities in a compressional z-pinch. A magnetohydrodynamic approach is followed as a first approximation to the problem. [1] M. Milanese, R. Moroso y J. Pouzo, J.Phys.D: Applied Physics 31, 85 (1998). [2]H. Schmidt, M. Sadowski, L. Jakubowski, E. Skladnik-Sadowska, J. Stanislawski y A. Szydlowski, J. Tech. Phys. 38, 121 (1997).

Herrera, Julio; Castillo, Fermín; Acuña, Hugo

2002-11-01

130

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

131

Inactivation Characteristics of Bacteria in Capacitively Coupled Argon Plasma  

Microsoft Academic Search

Plasma technology is being focused on the medical, food, and pharmaceutical fields for sterilization applications. The sterilizing effect of the 13.56-MHz radio-frequency (RF) plasma generated by using argon gas was studied using Staphylococcus aureus, one of the most common pathogens liable to hospital-acquired infections. The major focus of this paper was to perform a parametric study by varying the external-process

Sureshkumar; Sudarsan Neogi

2009-01-01

132

Smart Coating Technology by Gas Tunnel Type Plasma Spraying  

NASA Astrophysics Data System (ADS)

Nano-science & technology is one of the most important scientific fields, and the material processing using the nano-technology is now advanced towards more precise and controllable smart stage. Regarding thermal processing, an important key should be the the performance of the applied heat source. A plasma is fundamentally the most superior heat source, because of high temperature, high energy density, easy controllable, etc. Therefore more precious plasma system has been expected for smart thermal processing. The gas tunnel type plasma system developed by the author has high energy density and also high efficiency. The concept and the feature of this plasma system are explained and the applications to the various thermal processing are described in this report. One practical application is plasma spraying of ceramics such as Al_2O_3 and ZrO_2. The characteristics of these ceramic coatings were superior to the conventional ones. The ZrO_2 composite coating has the possibility of the development of high functionally graded TBC (thermal barrier coating). Another application of gas tunnel type plasma is surface modification of metals. For example the TiN films were formed in a very short time of 5 s. Now, advanced plasma application of spraying methods as a smart coating technology is expected to obtain the desired characteristics of ceramics such as corrosion resistance, thermal resistance, and wear resistance by reducing the porosity and increasing the coating density. One application of the smart coating technology is a formation of the metallic glass coating with high function, and another is Hydroxiapatite coating for bio-medical application. The formation process of those coatings and the coating characteristics were investigated in this study.

Kobayashi, A.

2008-07-01

133

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

SciTech Connect

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

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

2012-07-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

135

Paraformaldehyde for Surface Sterilization and Detoxification  

PubMed Central

Paraformaldehyde powder, depolymerized by heat, produced formaldehyde gas that was effective in sterilizing laboratory rooms, a mobile laboratory trailer, various surfaces, fiberglass filter medium, and specialized laboratory equipment. A sporulating and nonsporulating strain of bacteria, a virus, and a bacterial toxin were used as test agents. The dissemination procedures and equipment, the assay techniques, and the facilities and equipment sterilized were described. PMID:4977223

Taylor, Larry A.; Barbeito, Manuel S.; Gremillion, Gardner G.

1969-01-01

136

Plasma quench technology for natural gas conversion applications  

SciTech Connect

This paper describes the experimental demonstration of a process for direct conversion of methane to acetylene in a thermal plasma. The process utilizes a thermal plasma to dissociate methane and form an equilibrium mixture of acetylene followed by a supersonic expansion of the hot gas to preserve the produced acetylene in high yield. The high translational velocities and rapid cooling result in an overpopulation of atomic hydrogen which persists throughout the expansion process. The presence of atomic hydrogen shifts the equilibrium composition by inhibiting complete pyrolysis of methane and acetylene to solid carbon. This process has the potential to reduce the cost of producing acetylene from natural gas. Acetylene and hydrogen produced by this process could be used directly as industrial gases, building blocks for synthesis of industrial chemicals, or oligomerized to long chain liquid hydrocarbons for use as fuels. This process produces hydrogen and ultrafine carbon black in addition to acetylene.

Detering, B.A.; Kong, P.C.; Thomas, C.P. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1995-07-01

137

Classical transport equations for burning gas-metal plasmas  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

138

Mobility in a strongly coupled dusty plasma with gas  

E-print Network

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 $u_p$. The mobility $\\mu_p=u_p/F$ of the projectile's motion is obtained. Two regimes depending on $F$ are identified. In the high force regime, $\\mu_p \\propto F^{0.23}$, and the scattering cross section $\\sigma_s$ diminishes as $u_p^{-6/5}$. Results for $\\sigma_s$ 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

2014-01-01

139

Laser ablated copper plasmas in liquid and gas ambient  

NASA Astrophysics Data System (ADS)

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 (ne) determined using Stark broadening of the Cu I (3d104d1 2D3/2-3d104p1 2P3/2 at 521.8 nm) line is estimated and compared for both plasma plumes. The electron temperature (Te) 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.

2013-05-01

140

Heterogeneous reactions in non-thermal plasma flue gas desulfurization  

Microsoft Academic Search

This paper demonstrates that the main reaction mechanism of flue gas desulfurization (FGD) by pulsed corona discharge or electron beam, which generates non-thermal plasmas (NTP), is heterogeneous. The experimental results in this paper suggest that the main reactions in FGD by NTP are activated reactions in liquid phase. According to Huie’s mechanism, it is considered that the ionic radical SO-3

Ruinian Li; Keping Yan; Jinsong Miao; Xiaoli Wu

1998-01-01

141

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

142

Survey of sterile technique used by dermatologic surgeons.  

PubMed

A survey was made of the sterile technique practices of dermatologists interested in dermatologic surgery. The steam autoclave is the most popular method for sterilizing surgical instruments. Dry heat sterilization is often used, as is cold, chemical sterilization. The most popular agent for chemical sterilization continues to be quaternary ammonium compounds despite warnings to the contrary. Gas sterilization is rarely used. Alcohol is the most popular agent for prepping the skin and iodophors are also quite popular. Dermatologists are now wearing gloves for most procedures. Prophylactic antibiotics are used minimally in surgical cases, as is recommended by established standards. PMID:3385030

Sebben, J E

1988-05-01

143

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

144

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

Microsoft Academic Search

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

D. Degout; A. Catherinot

1986-01-01

145

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

146

Sensitive determination of piritramide in human plasma by gas chromatography.  

PubMed

A selective and sensitive method for the determination of piritramide in human plasma is described. A 1-ml aliquot of plasma was extracted with 10 ml of hexane-isoamyl alcohol (99.5:0.5, v/v) (extraction efficiency 86%) after addition of 50 microliters of 2 M ammonia and 20 microliters of aqueous strychnine solution (100 ng per 10 microliters) as internal standard. Gas chromatography was performed with J&W DB-1, 30 m x 0.53 mm I.D. separation column, film thickness 1.5 microns, using an nitrogen-phosphorus-sensitive detector. The assay was linear in the concentration range 3.75-2250 ng/ml (r = 0.999), with a lower limit of detection of 1-2 ng/ml. The precision was determined using spiked plasma samples (10 and 50 ng/ml), with coefficients of variation of 3.5 and 3.1% (intra-day; n = 5) and 4.6 and 4.1% (inter-day; n = 4). In the range 3.75-150 ng/ml, the accuracy of the assay was 3.36%. The method was used for the determination of piritramide plasma concentrations in patients receiving intra- or post-operative analgesia. PMID:1810954

Michaelis, H C; Kietzmann, D; Neurath, H; Jongepier, U; Schilling, B

1991-11-15

147

Electron gas oscillations in plasma. Theory and applications  

E-print Network

We analyze the obtained solutions of the non-linear Shr{"o}dinger equation for spherically and axially symmetrical electrons density oscillations in plasma. The conditions of the oscillations process existence are examined. It is shown that in the center or on the axis of symmetry of the systems the static density of electrons enhances. This process results in the increasing of density and pressure of the ion gas. We suggest that this mechanism could occur in nature as rare phenomenon called the 'fireball' and could be used in carrying out the research concerning controlled fusion. The description of the experiments, carried out for the purpose to generate long-lived spherical plasma structures, is presented.

Dvornikov, M S; Dvornikov, Maxim; Dvornikov, Sergey

2003-01-01

148

Improvement of the characteristics of a plasma torch at low gas flow rate  

Microsoft Academic Search

It is shown that the gas dynamics of a plasma torch and its characteristics depend on the configuration of the discharge chamber. Tapered boring at the cylindrical anode inlet (10° over a length of 11 mm) makes it possible to increase the arc voltage, torch efficiency, and enthalpy of the plasma jet at low gas flow rates. At high gas

A. Marotta

1994-01-01

149

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

150

Approximate Solutions of Quantum Equations for Electron Gas in Plasma  

E-print Network

We have obtained the solutions of linearized Shr{\\"o}dinger equation for spherically and axially symmetrical electrons density oscillations in plasma in the approximation of the self-consistent field. It was shown that in the center or on the axis of symmetry of such a system the static density of electrons can enhance, which leads to the increasing of density and pressure of ion gas. We suggest that this mechanism could be realized in nature as rare phenomenon called the 'fireball' and could be used in carrying out the research concerning controlled fusion.

M. Dvornikov; S. Dvornikov; G. Smirnov

2002-03-14

151

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

152

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

153

IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 34, NO. 4, AUGUST 2006 1317 Killing of S. mutans Bacteria Using a Plasma  

E-print Network

atmospheric-pressure glow discharge. It is intended for dental or medical applications [8]­[15]. Radio-frequency plasma, plasma applica- tions, sterilization. I. INTRODUCTION ATMOSPHERIC-PRESSURE glow discharges show such as helium to lower the breakdown voltage, a significant gas flow rate, high-frequency power, a cathode

Goree, John

154

The influence of sterilization method on wear performance of the low contact stress total knee system.  

PubMed

Sterilization method changes to the Low Contact Stress (LCS) Total Knee System (DePuy Orthopaedics Inc, Warsaw, Ind) have resulted in progressive improvements in wear resistance. Initially, the system used the traditional gamma in air irradiation sterilization method, but was transitioned to Gas plasma sterilization. The Gas plasma technique did not introduce free radicals that subsequently oxidize with extended shelf aging found with gamma in air irradiation. This oxidation has demonstrated a significant reduction in mechanical properties leading to increased wear. The introduction of Gas plasma was also accompanied by a transition to polyethylene resins that no longer contained calcium stearate, surmised to influence the rate of oxidation. More recently, gamma irradiation and storage of the polyethylene components in an essentially oxygen-free environment imparted by gamma irradiation in a vacuum foil pouch (GVF), has been shown to protect the implant from oxidation. Additionally, the GVF process imparts the beneficial effects of moderate crosslinking that has been demonstrated to improve wear resistance. PMID:11866160

McNulty, Donald E; Liao, Yen-Shuo; Haas, Brian D

2002-02-01

155

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

156

Sterilizing the Poor  

ERIC Educational Resources Information Center

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

Rothman, Sheila M.

1977-01-01

157

The interaction of an atmospheric pressure plasma jet using argon or argon plus hydrogen peroxide vapour addition with bacillus subtilis  

Microsoft Academic Search

This paper reports that an atmospheric pressure dielectric barrier discharge plasma jet, which uses argon or argon + hydrogen peroxide vapour as the working gas, is designed to sterilize the bacillus subtilis. Compared with the pure argon plasma, the bacterial inactivation efficacy has a significant improvement when hydrogen peroxide vapour is added into the plasma jet. In order to determine

San-Xi Deng; Cheng Cheng; Guo-Hua Ni; Yue-Dong Meng; Hua Chen

2010-01-01

158

Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source  

NASA Astrophysics Data System (ADS)

This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode.

Tarifeño-Saldivia, Ariel; Soto, Leopoldo

2014-12-01

159

Imaging gas and plasma interactions in the surface-chemical modification of polymers using micro-plasma jets  

Microsoft Academic Search

This paper reports on the correlation between gas flow and plasma behaviour in the outflow of a micro-atmospheric pressure plasma jet operating in helium using both 2D optical imaging and Schlieren photography. Schlieren photography shows that the helium outflow changes from laminar to turbulent conditions after distances between 20 and 50 mm from the nozzle. Above a flow rate of

Jun-Seok Oh; Olumuyiwa T. Olabanji; Craig Hale; Raffaello Mariani; Konstantinos Kontis; James W. Bradley

2011-01-01

160

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

161

Gas Chromatographic Analysis of Cyclophosphamide in Plasma and Tissues Using Nitrogen-Phosphorus Detection  

Microsoft Academic Search

A gas chromatographic method for the analysis of cyclophosphamide in plasma, blood, and organ tissues is described. This method involves extraction of aliquots of plasma or tissue homo-genate in alkaline condition with ether. The extracted drug is derivatized with heptafluorobutyric anhydride followed by gas chromatographic separation via a glass column of 183 cm × 2 mm i. d. packed with

M. S. Balachandran Nayar; Lo-Yin Lin; Suk Han Wan; Kenneth K. Chan

1979-01-01

162

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

163

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

164

Decomposition of dilute trichloroethylene by nonthermal plasma processing-gas flow rate, catalyst, and ozone effect  

Microsoft Academic Search

Decomposition performance of dilute (100-1000 ppm) trichloroethylene (TCE) contaminated in air by using nonthermal plasma processing was studied to improve the decomposition efficiency. Three kinds of experiments were performed. One is the observation of the decomposition efficiency related to the processing gas flow rate. There exists an optimal gas flow rate for our reactor. The second experiment is the plasma

Tetsuji Oda; Kei Yamaji; Tadashi Takahashi

2004-01-01

165

Discharge Characteristics of a Gas-Filled Capillary Plasma for Laser Wakefield Acceleration  

Microsoft Academic Search

A gas-filled capillary plasma source for potential use in conjunction with laser wakefield acceleration is developed, and its discharge characteristics are presented here. In the capillary, helium or hydrogen gas (?150 torr in pressure) is injected, and a pulsed high voltage (?25 kV) is applied for electrical discharge and plasma production. The discharge properties of the helium and hydrogen gases

M. S. Kim; D. G. Jang; H. S. Uhm; S. W. Hwang; I. W. Lee; H. Suk

2011-01-01

166

Shrouding of Thermal Plasma Jets Generated by Gas-Water Torch  

Microsoft Academic Search

The ambient air is entrained intensively into atmospheric pressure thermal plasma jets. A system for shielding plasma jet has been used to improve jet characteristics and reduce oxygen content. Different gases have been applied as a shroud gas - argon, acetylene, methane, mixtures of acetylene-nitrogen and hydrogen-nitrogen. All shroud gases used in experiments affected plasma jet making the profiles of

T. Kavka; M. Hrabovsky; O. Chumak; V. Kopecky

167

Determination of paroxetine levels in human plasma using gas chromatography with electron-capture detection.  

PubMed

A simple, rapid and sensitive procedure using gas chromatography with electron-capture detection to measure paroxetine levels in human plasma has been developed. The analyte was extracted from plasma with ethyl acetate after basification of the plasma and then derivatized with heptafluorobutyric anhydride before gas chromatographic separation. The calibration curves were linear, with typical r2 values >0.99. The assay was highly reproducible and gave peaks with excellent chromatographic properties. PMID:11145064

Lai, C T; Gordon, E S; Kennedy, S H; Bateson, A N; Coutts, R T; Baker, G B

2000-12-01

168

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

169

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

170

Hysteroscopic tubal sterilization.  

PubMed

This article provides an overview of the history of hysteroscopic sterilization including the current state of the art and future ideals. Unlike laparoscopic techniques, sterilization by hysteroscopy can be performed in an outpatient setting without general anesthesia. Many attempts have been made to develop a safe and effective method, but until recently, without success. The Essure system is the first one that seems to be a realistic alternative to laparoscopic sterilization, but is irreversible. The search is still on for the optimum method of hysteroscopic sterilization. PMID:15450329

Magos, Adam; Chapman, Lynne

2004-09-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

172

Effect of Deuterium Gas Puff On The Edge Plasma In NSTX  

SciTech Connect

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

Zweben, S. J.

2014-02-20

173

Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma  

NASA Astrophysics Data System (ADS)

This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films.

Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

2014-03-01

174

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

175

Influence of reactive oxygen species on the sterilization of microbes  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

176

Quantifying the effect of resin type and sterilization method on the degradation of ultrahigh molecular weight polyethylene after 4 years of real-time shelf aging.  

PubMed

Alternative sterilization methods including ethylene oxide, gas plasma, and gamma-radiation in an inert environment were implemented in the late 1990s, to limit oxidative degradation of ultrahigh molecular weight polyethylene (PE). There was also a simultaneous transition to PE resins that did not contain calcium stearate. Shelf storage duration of PE inserts following gamma-irradiation in air has been correlated to poor clinical performance and increased wear. This study aimed to determine how sterilization method and resin type influenced degradation of PE after 4 years of real-time shelf aging. It was hypothesized that gamma-irradiation and stearate containing resins would incur significantly more degradation than nonradiated, stearate-free resins. Gamma-irradiated PE samples in air and nitrogen had a significantly increased density and oxidation index, compared to nonirradiated PE after 4 years of shelf aging. Alternative sterilization methods such as ethylene oxide and gas plasma appeared to have significantly less oxidation regardless of PE resin type. A partial correlation demonstrated that density and oxidation index were not correlated (r(2) = 0.079) when examining the influence of sterilization method. The data supported that after 4 years of real-time shelf aging, the type of sterilization method had a larger influence on PE degradation than resin type. PMID:15127395

Willie, Bettina M; Ashrafi, Shadi; Alajbegovic, Sanjin; Burnett, Trever; Bloebaum, Roy D

2004-06-01

177

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

178

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

179

Formation of an out-of-electrode plasma in a high-voltage gas discharge  

NASA Astrophysics Data System (ADS)

The formation of an out-of-electrode plasma in a high-voltage gas discharge is studied. The occurrence and self-maintenance of a gas discharge and its associated plasma fluxes on the straight portions of electrical field lines are predicted theoretically and confirmed experimentally. It is shown that the focusing of the gas discharge and plasma fluxes is provided by increasing the length of the field line straight portions toward the symmetry axis of a hole in the anode. It is found that, when the discharge power (more specifically, an accelerating voltage applied to the electrodes of the gas-discharge tube) rises, the straight portions of the field lines elongate and concentrate near the symmetry axis of the hole in the anode. Recommendations are given on using the out-of-electrode plasma in surface micro- and nanostructuring.

Kolpakov, V. A.; Kolpakov, A. I.; Podlipnov, V. V.

2013-04-01

180

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

SciTech Connect

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

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

2009-05-15

181

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

182

Effect of shield gas on the size distribution of aluminum nanoparticles synthesized in thermal plasma reactor  

NASA Astrophysics Data System (ADS)

Synthesizing nano-particles with narrow size distribution in the gas phase process, via thermal plasma reactor is a challenge. The paper addresses this problem by introducing a crucial modification in thermal plasma reactor, used to produce nano-aluminum particles for propellant applications. The size distribution is assessed by transmission electron microscopy.

Varma, Vijaykumar B.; Tank, Chiti M.; Nandi, Amiya; Pant, Arti; Prashant, Hima; Pandey, R. K.; Das, A. K.; Bhoraskar, S. V.; Mathe, V. L.

2013-02-01

183

Adapting Continuous-Flow Plasma Jets for Intermittent Ignition in Gas Turbine Combustors  

Microsoft Academic Search

The effectiveness as pulsed igniters of plasma jets originally designed as continuous-flow radical generators, developed for flame stabilisation, is investigated with particular reference to ignition in aircraft gas turbines. It is found that these devices are able to ignite kerosene sprays in aircraft flame tubes more effectively than conventional high energy igniters, with either nitrogen or air as the plasma

G. K. CHERIYAN; K. KRALLIS; F. J. WEINBERG

1990-01-01

184

Title of Dissertation: MODELING LASER PULSE EVOLUTION IN IONIZING GAS AND PLASMA WITH  

E-print Network

of laser pulse evolution and plasma response in simulations ranging from modeling laser wakefieldABSTRACT Title of Dissertation: MODELING LASER PULSE EVOLUTION IN IONIZING GAS AND PLASMA: Professor Thomas M. Antonsen, Jr., Department of Physics The interaction of high intensity laser pulses

Anlage, Steven

185

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

NASA Technical Reports Server (NTRS)

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

1973-01-01

186

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

187

Plasma-enhanced chemical vapor deposition carbon nanotubes for ethanol gas sensors  

Microsoft Academic Search

Carbon nanotubes (CNTs) have been fabricated by microwave plasma-enhanced chemical vapor deposition for detecting the presence of ethanol vapor. The conductance of the CNTs decreases when the sensors are successively exposed to ethanol vapor at room temperature. The surface of the CNTs was modified in oxygen plasma to elevate the detection sensitivity for ethanol. Successful utilization of CNTs in gas

Chia-Te Hu; Chun-Kuo Liu; Meng-Wen Huang; Sen-Hong Syue; Jyh-Ming Wu; Yee-shyi Chang; Jien-W. Yeh; Han-C. Shih

2009-01-01

188

On the effects of electron gas viscosity on the interaction of microwave and magnetoactive plasma  

Microsoft Academic Search

A method for calculating microwave propagation through magnetoactive, low-pressure plasma under conditions of electron-cyclotron resonance (ECR) is presented. The influence of electron gas viscosity on the microwave propagation is investigated. The numerical calculations show the importance of the viscosity effects on microwave propagation through the high concentrated, magnetoactive plasma, especially for strong ECR interaction

Andrei B. Petrin

2000-01-01

189

Experimental investigation of development of fully turbulent plasma jet generated by hybrid gas-water torch  

Microsoft Academic Search

Thermal plasma jets are characterized by strong interaction with surrounding atmosphere. Such jets in most cases represent\\u000a fully turbulent flow. Fast transition of the plasma jet generated by the hybrid gas-water torch to turbulent behavior is caused\\u000a by a strong difference between ambient air density and density of the plasma, which is extremely low due to high jet temperature.\\u000a Development

T. Kavka; V. Kopecky; V. Sember; A. Maslani

2006-01-01

190

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

191

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

Microsoft Academic Search

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

J. Goree; Bin Liu; David Drake

2006-01-01

192

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

193

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

194

[Application of argon-nitrogen mixed gas inductively coupled plasma in elements and isotopes analysis].  

PubMed

To improve the precision and accuracy of elements and isotopes analysis in traditional Ar-ICP, the addition of nitrogen in ICP has been widely used. The present review focused on the discussions of the basic physical and chemical properties of the Ar-N2 mixed gas inductively coupled plasma and the mechanisms of the special nature of Ar-N2 mixed gas plasma. The applications of Ar-N2 inductively coupled plasma in spectral analysis and mass spectrometry analysis in the past 40 years were summarized. The authors also give an overall outlook on the application of this technology. PMID:24059205

Liu, Sheng-Hua; Chen, Tao; Li, Zhen; Wang, Li-Yun; Liu, Yong-Sheng; Hu, Sheng-Hong; Hu, Zhao-Chu

2013-07-01

195

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

196

Ozone-mist spray sterilization for pest control in agricultural management  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

197

Mechanisms of disruptions caused by noble gas injection into tokamak plasmas  

Microsoft Academic Search

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

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

2005-01-01

198

On anomalous temporal evolution of gas pressure in inductively coupled plasma  

SciTech Connect

The temporal measurement of gas pressure in inductive coupled plasma revealed that there is an interesting anomalous evolution of gas pressure in the early stage of plasma ignition and extinction: a sudden gas pressure change and its relaxation of which time scales are about a few seconds and a few tens of second, respectively, were observed after plasma ignition and extinction. This phenomenon can be understood as a combined result between the neutral heating effect induced by plasma and the pressure relaxation effect for new gas temperature. The temporal measurement of gas temperature by laser Rayleigh scattering and the time dependant calculations for the neutral heating and pressure relaxation are in good agreement with our experimental results. This result and physics behind are expected to provide a new operational perspective of the recent plasma processes of which time is very short, such as a plasma enhanced atomic layer deposition/etching, a soft etch for disposal of residual by-products on wafer, and light oxidation process in semiconductor manufacturing.

Seo, B. H.; Chang, H. Y. [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)] [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); You, S. J.; Kim, J. H.; Seong, D. J. [Center for Vacuum Technology, Korea Research Institute of Standards and Science, Daejeon 305-306 (Korea, Republic of)] [Center for Vacuum Technology, Korea Research Institute of Standards and Science, Daejeon 305-306 (Korea, Republic of)

2013-04-01

199

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

200

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

201

Decontamination n Sterilization  

E-print Network

stearothermophilis) 2.10 Decontamination Heat #12;n Dry heat sterilization n Denaturation of proteins: 1600 ­ 1700 C minimum 20 min. exposure n Examples: phenolics, iodophores, chlorine compounds, alcohols 2

Collins, Gary S.

202

Sterilization by Laparoscopy  

MedlinePLUS

... sleep-like state to prevent pain during surgery. Human Immunodeficiency Virus (HIV): A virus that attacks certain cells of the body’s immune system and causes acquired immunodeficiency syndrome (AIDS). Hysteroscopic Sterilization: ...

203

Sterilization of talc for pleurodesis. Available techniques, efficacy, and cost analysis.  

PubMed

Although talc has been used as a pleurodesis agent since 1935, a sterilization protocol has not been established. We obtained USP asbestos-free talc from six different suppliers and sterilized each using dry heat, gamma irradiation, and ethylene oxide gas. Aerobic, anaerobic, and fungal cultures were obtained prior to sterilization, and 1, 30, and 90 days after sterilization. Bacillus species were cultured from all six unsterilized specimens and coagulase-negative Staphylococcus grew from two unsterilized specimens. No growth of organisms was found following any method of sterilization. The cost of sterilization per 5-g packet of talc was $4.74, $7.85, and $16.25 for heat, ethylene oxide, and gamma irradiation, respectively. In conclusion, untreated talc is not sterile. Sterilization by prolonged dry heat exposure, ethylene oxide gas, and gamma irradiation are all effective, with dry heat being the least expensive. PMID:7705111

Kennedy, L; Vaughan, L M; Steed, L L; Sahn, S A

1995-04-01

204

Uncertainty and sensitivity analysis of gas-phase chemistry in a CHF3 plasma  

NASA Astrophysics Data System (ADS)

A global uncertainty and sensitivity analysis is performed for a detailed gas-phase reaction set in a CHF3 plasma. The goal of this paper is to ascertain the uncertainties in plasma reactor model results (plasma and radical densities) that originate from the uncertainties in the gas-phase chemistry database. We discuss the rates of reactions and their uncertainties. Comparisons with experimental data show that gas-phase rate uncertainties do not explain the disagreements at higher pressures (>30 mTorr). We also find that electron impact dissociation reactions of dominant neutrals are the largest sources of uncertainties. HF kinetics are also found to be critical in determining radical and feedstock gas densities. Relative ion densities are uncertain due to poor understanding of charge transfer mechanisms.

Bose, Deepak; Rao, M. V. V. S.; Govindan, T. R.; Meyyappan, M.

2003-05-01

205

The Role of Oxygen in a Large Area of RF-Powered Atmospheric Pressure Dielectric Barrier Glow Discharge Plasma in Sterilization  

Microsoft Academic Search

A nonequilibrium Ar\\/O2 plasma at atmospheric pressure was generated between two parallel square electrodes by a 13.56-MHz power supplier. Experimental results demonstrate that the Ar\\/O2 plasma more effectively kills Staphylococcus aureus and Escherichia coli than the Ar plasma. When the O2 flow rate increases from 0 to 100 sccm step by step, the discharge voltage and the radio-frequency (RF) current

Hua Pang; Qiang Chen; Bin Li; Fei Fei; Size Yang

2011-01-01

206

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

Microsoft Academic Search

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

Kyoung Doo Kang; Sang Hee Hong

1999-01-01

207

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. PMID:24228084

McMartin, K

2013-01-01

208

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

E-print Network

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

209

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

210

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

211

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

212

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

NASA Astrophysics Data System (ADS)

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

Cooper, Christopher; Gekelman, Walter

2011-11-01

213

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

214

Laser Thomson scattering in Ar and N2 gas plasmas.  

NASA Astrophysics Data System (ADS)

Laser Thomson scattering is now being used in low density ( ~10^11cm-3) laboratory plasmas. Here the second harmonic of a Nd:YAG laser was used to perform Thomson scattering in an inductively coupled GEC cell, with an ICCD as detector. Thomson scattering measurements have been made in argon and nitrogen plasmas between 5-250mTorr and 10-300W. The electron densities and temperatures determined are shown to compare reasonably with Langmuir probe measurements in similar conditions. However the EEDF's derived from the Thomson scattering measurements show the presence of low energy electrons (<=3eV) not seen in the probe measurements. This potentially important finding is now being investigated more closely. In nitrogen the analysis is further complicated by factors such as Raman scattering and complex plasma emission.

Thompson, Catherine; Steen, Philip; Craig, Gary; Morrow, Tom; Graham, Bill

2001-10-01

215

The sterile inflammatory response  

PubMed Central

The acute inflammatory response is a double-edged sword. On the one hand it plays a key role in initial host defense particularly against many infections. On the other hand its aim is imprecise and as a consequence, when it is drawn into battle, it can cause collateral damage in tissues. In situations where the inciting stimulus is sterile, the cost-benefit ratio may be high; because of this, sterile inflammation underlies the pathogenesis of a number of diseases. While there have been major advances in our understanding of how microbes trigger inflammation, much less has been learned about this process in sterile situations. This review focuses on a subset of the many sterile stimuli that can induce inflammation – specifically dead cells and a variety of irritant particles, including crystals, minerals, and protein aggregates. Although this subset of stimuli is structurally very diverse and might appear to be unrelated, there is accumulating evidence that the innate immune system may recognize them in similar ways and stimulate the sterile inflammatory response via common pathways. Here we review established and emerging data about these responses. PMID:20307211

Rock, Kenneth L.; Latz, Eicke; Ontiveros, Fernando; Kono, Hajime

2015-01-01

216

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

217

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

218

Analysis of whole blood samples with low gas flow inductively coupled plasma-optical emission spectrometry.  

PubMed

Low gas flow ICP-OES with a total argon consumption below 0.7 L/min is introduced for the analysis of trace elements in blood samples to investigate the influence of samples containing an organic solvent in a demanding matrix on the performance of this plasma for the first time. Therefore, gadolinium was determined in human plasma samples and mercury in red blood cells, human plasma, and precipitated plasma protein fraction. Limits of detection (LOD) were determined to be in the low microgram per liter range for the analytes and the accuracy of the method was assessed by comparison with a conventional Fassel-type torch-based ICP-OES. It was proven that the low gas flow ICP-OES leads to comparable results with the instrument based on the Fassel-type torch. PMID:25240935

Nowak, Sascha; Künnemeyer, Jens; Terborg, Lydia; Trümpler, Stefan; Günsel, Andreas; Wiesmüller, Gerhard A; Karst, Uwe; Buscher, Wolfgang

2015-01-01

219

Gas Kinetic Study of Magnetic Field Effects on Plasma Plumes  

E-print Network

the co-chair of my committee from who I learned a great deal about the eld of plasma physics. He provided a needed experimental perspective to my research and gave valuable research input and advice. I would also like to thank Dr. Jacques Richard... for introducing me to the great elds of space propulsion and plasma physics and for his encouragement and guidance through the years. Lastly I would like to thank Dr. John Shebalin for becoming my mentor at NASA. I have not only learned a great deal about...

Ebersohn, Frans 1987-

2012-12-07

220

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

221

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

222

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

223

[Sterilization of dental instruments].  

PubMed

Instruments used by dentists are often sterilized with steam sterilization. At this moment three types of processes are described in the European norms: Type N, S and B. According to the norms type N can be used for non-wrapped non-hollow instruments and non-porous instruments, type S can be used for instruments specified by the manufacturer and type B can be used for wrapped, hollow and porous instruments. The principles on which the sterilizors are based are described. It is concluded that before purchasing the sterilizor the method of working and instruments to be sterilized must specified. In most cases a type B process is preferable in order to gaurantee to be certain to have an effective and reproducible process. PMID:11486515

van Doornmalen, J P; Verschueren, M; Dankert, J; Rietmeijer, A G

2001-07-01

224

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

225

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

226

Sterile neutrinos in the early universe  

SciTech Connect

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

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

1990-11-14

227

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

228

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

229

Low-temperature plasma-catalytic oxidation of formaldehyde in atmospheric pressure gas streams  

Microsoft Academic Search

Formaldehyde (HCHO) is a typical air pollutant capable of causing serious health disorders in human beings. This work reports plasma-catalytic oxidation of formaldehyde in gas streams via dielectric barrier discharges over Ag\\/CeO2 pellets at atmospheric pressure and 70 °C. With a feed gas mixture of 276 ppm HCHO, 21.0% O2, 1.0% H2O in N2, ~99% of formaldehyde can be effectively

Hui-Xian Ding; Ai-Min Zhu; Fu-Gong Lu; Yong Xu; Jing Zhang; Xue-Feng Yang

2006-01-01

230

Production of hydrogen-rich gas by plasma reforming of dimethyl ether  

Microsoft Academic Search

The production of hydrogen-rich gas by plasma reforming of dimethyl ether (DME) was conducted in a self-made three-cavity reformer at atmospheric pressure and ambient temperature. The effects of reformer structure parameters, electrode material, heat transfer characteristics, and operation parameters on the gas composition and hydrogen yield were investigated. The results indicated that the yield of hydrogen increases with the increase

Kui-feng MA; Xing-hu LI

2010-01-01

231

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

232

Continuous sterilization of plumbing systems  

NASA Technical Reports Server (NTRS)

Continuous sterilization of plumbing, such as in hospitals, clinics, and biological testing laboratories is possible with ethylene oxide/Freon 12 (ETO/F-12) humidifier developed for sterilization of potable water systems.

Bryan, C. J.; Moyers, C. V.; Wright, E. E., Jr.

1979-01-01

233

Time dependent neutral gas transport in tokamak edge plasmas  

NASA Astrophysics Data System (ADS)

The effects of neutral particles on the edge plasma conditions play a key role in divertor and limiter physics. In computational models they are usually treated in steady state approximation (instantaneous relaxation). However, the characteristics transport time scale is comparable to the ion acustic time scale. Thus neutral atoms relax to their steady state distributions much slower than electron temperature profiles along the fieldlines are established. A computational assessment of divertor or limiter dynamics requires ultimately an extension to time dependent algorithms. The numerical procedure in the EIRENE Monte Carlo code is presented. A first numerical study of ELM's in the ASDEX-Upgrade divertor plasma has been carried out and the results are briefly discussed.

Reiter, D.; May, Chr.; Coster, D.; Schneider, R.

1995-04-01

234

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

235

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

236

Sterilization of Native Americans  

ERIC Educational Resources Information Center

The U.S. State Department's Agency for International Development (AID) is spending more than $143 million this year for population control measures in over 70 nations around the world and it is estimated that as much as $10 million was spent in one year for surgical sterilization procedures. (JC)

Dillingham, Brint

1977-01-01

237

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

238

Collective Refraction of a Beam of Electrons at a Plasma-Gas P. Muggli, S. Lee, T. Katsouleas  

E-print Network

1 Collective Refraction of a Beam of Electrons at a Plasma-Gas Interface P. Muggli, S. Lee, T, the results of an experiment to measure the refraction of a particle beam were reported [P. Muggli, et al., Nature 453, May 3, 2001]. The refraction takes place at a passive interface between a plasma and a gas

239

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

240

Motion of plasma-dust structures and gas in a magnetic field.  

PubMed

Numerous studies have revealed that the superposition of magnetic field causes plasma-dust structures to rotate in the plane normal to the field. The only explanation for this rotation found in the literature is that the plasma-dust structures are acted upon by the forces of ion entrainment (ion drag forces) from ions moving under the effect of the magnetic field in the azimuthal direction. However, this study demonstrates that the experimentally observed motion of plasma-dust structures cannot be explained by the forces of ion entrainment alone. We show that the observed motion of plasma-dust structures is further affected by their entrainment by gas rotating under the effect of the moment of force IxB , which exists in regions of discharge with nonuniform magnetic field in the vicinity of solenoid end faces, as well as at the narrowing of cross section of the discharge channel. An eddy electric current exists in a discharge with strata in a uniform magnetic field; this current causes the rotation of gas and is associated with the noncollinearity of the gradients of plasma density and temperature. Estimates are provided for the density of this current and for its impact on the rotation of gas in a magnetic field. Recent experimental data by Karasev [Phys. Rev. E 74, 066403 (2003)] are discussed. PMID:19392058

Nedospasov, A V

2009-03-01

241

Freezing and melting of 3D complex plasma structures under microgravity conditions driven by neutral gas pressure manipulation  

E-print Network

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

S. A. Khrapak; B. A. Klumov; P. Huber; V. I. Molotkov; A. M. Lipaev; V. N. Naumkin; H. M. Thomas; A. V. Ivlev; G. E. Morfill; O. F. Petrov; V. E. Fortov; Yu. Malentschenko; S. Volkov

2011-04-12

242

Freezing and melting of 3D complex plasma structures under microgravity conditions driven by neutral gas pressure manipulation  

E-print Network

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

Khrapak, S A; Huber, P; Molotkov, V I; Lipaev, A M; Naumkin, V N; Thomas, H M; Ivlev, A V; Morfill, G E; Petrov, O F; Fortov, V E; Malentschenko, Yu; Volkov, S

2011-01-01

243

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

244

Guiding of terawatt laser pulses in a plasma waveguide produced in an elongated pulsed gas jet  

Microsoft Academic Search

We have recently demonstrated a high repetition rate gas jet, designed to eliminate the problem of refraction in the injection of high intensity laser pulses into plasma waveguides. A sequence of measured electron density from a 1.5 cm long argon jet waveguide is shown. We show electron density profiles as a function of axial distance at the end of the

I. Alexeev; S. Nikitin; I. Fan; H. M. Milchberg

1999-01-01

245

Bright nitriding of Cr-Mo-steels in plasma and gas  

SciTech Connect

Although the reduction of the white layer in special gas atmospheres directly after nitriding and bright nitriding were reported a long time ago, the white layer is mostly removed by mechanical or chemical means in industrial practice. The main reason for this is poor process control. However, new requirements such as the duplex treatment (nitriding + hardcoating), demand a more detailed examination of bright nitriding. Today, new possibilities exist for process control in gas nitriding by solid electrolyte sensors. Steel grades 17CrMoV10 and 31CrMoV9 were bright nitrided in gas and plasma. In contrast to the above experiments, in the two-step technology no white layer forms in the first step (20min) at a higher nitriding potential. By this, the formation of a soft surface layer (of iron) can be avoided. Limits of this technology--for instance in the depth of the formed nitrided case--are discussed. Reasons for the often discussed faster nitriding in plasma are explained on the basis of the experimental results. The influence of ion bombardment in plasma nitriding on the activation of the surface and the nitriding results is discussed in comparison to gas nitriding. In this context the advantages of plasma nitriding--with respect to higher chromium alloyed steels (>5%Cr), which tend to passivation--are shown.

Larisch, B.; Spies, H.J.; Hoeck, K. [Inst. of Materials Engineering, Freiberg (Germany)

1995-12-31

246

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

247

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

NASA Astrophysics Data System (ADS)

An atmospheric plasma spraying process is investigated in this work by using experimental approach and mathematical modelling. Emphasis was put on the gas shrouded nozzles, their design, and the protection against the mixing with the surrounding air, which they give to the plasma jet. First part of the thesis is dedicated to the analysis of enthalpy probe method, as a major diagnostic tool in this work. Systematic error in measuring the stagnation pressure, due to a big temperature difference between the plasma and the water-cooled probe, is investigated here. Parallel measurements with the enthalpy probe and an uncooled ceramic probe were performed. Also, numerical experiments were conducted, using the k-? model of turbulence. Based on the obtained results, a compensating algorithm for the above error is suggested. Major objective of the thesis was to study the plasma spraying process, and potential benefits from using the gas shrouded nozzles. Mathematical modelling was used to perform the parametric study on the flow pattern inside these nozzles. Two nozzles were used: a commercial conical nozzle, and a custom-made curvilinear nozzle. The later is aimed towards elimination of the cold air entrainment, recorded for the conical nozzle. Also, parametric study on the shrouding gas and its interaction with the plasma jet was carried out. Two modes of the shrouding gas injection were tested: through sixteen injection ports, and through a continuous slot, surrounding the plasma jet. Both nozzles and both injection modes were thoroughly tested, experimentally and numerically. The curvilinear nozzle completely eliminates the cold air entrainment and yields significantly higher plasma temperature. Also, injection through the continuous slot resulted in a much better protection of the plasma jet. Both nozzles were used to perform the spraying tests. Obtained coatings were tested on porosity, adhesion strength, and micro- structure. These tests indicated better micro-structure of the coatings sprayed by the curvilinear nozzle. Also, their porosity was significantly lower, and the adhesion strength was higher for more than 25%. The overall results suggest that the curvilinear nozzles represent a much better solution for the gas shrouded plasma spraying.

Jankovic, Miodrag M.

248

Fast gas injection system for plasma physics experiments  

NASA Astrophysics Data System (ADS)

A system has been developed for fast, feedback controlled injection of hydrogen and various other gases into a vacuum system. Gas flow is through short (about 30-mm length), submillimeter diameter tubing at pressures in the fluid flow regime. The flow is controlled by a piezoelectric valve and measured by a miniature pressure sensor mounted in the body of the valve. Flow rates from a single valve of up to 500 Torr liter/s for hydrogen have been obtained. Response time of the flow is a rise time of 0.5 ms (with a 3-ms ringing decay time) and a fall time of 0.3 ms. The flow rate is basically a linear function of the measured pressure. A model has been developed to explain the observed functional dependence of flow rate on pressure, gas type, and tube radius.

Bates, S. C.; Burrell, K. H.

1984-06-01

249

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

250

High-speed Camera observation of Supersonic Gas Injector and NSTX Plasma edge  

NASA Astrophysics Data System (ADS)

A 50k fps CMOS digital camera from Canadian Photonics Labs has been implemented to observe the gas plume development and penetration using a D-alpha filter during tests of a Supersonic Gas Injector (SGI) in CDX-U. The use of a SGI has been shown to improve plasma fueling over traditional gas puffing. Other applications for the fast camera include observing the motion of the liquid lithium that forms the main limiter in CDX-U. Preliminary testing and setup on the camera has been performed using views of the plasma edge in NSTX. LabVIEW software is employed as a means for control and trigger of the camera, as well as post-download image processing and data acquisition. Results from tests on the projects will be presented, along with data acquisition methods. Work supported by the US DOE under grant number DE-AC02-76CH-03073

Frost, M.; Majeski, R.; Kaita, R.; Gray, T.; Spaleta, J.; Marfuta, P.; Timberlake, J.; Angelini, S.; Wolfe, C.

2004-11-01

251

[Studies on response characteristics of Cl, Br, I of microwave plasma torch atomic emission detector for gas chromatography].  

PubMed

The present paper deals with a microwave plasma torch atomic emission detector for gas chromatography. Argon is used as support gas, carrier gas and make-up gas. The effect of oxygen scavenger gas on the detection performance for chlorine, bromine and iodine is discussed. Detection limits, dynamic ranges, relative standard deviations and response characteristics of GC-MPT-AED for chlorine, bromine and iodine in organic compounds were studied. The results are favorable in comparing with GC-ICP-AED. PMID:12541563

Shi, Y H; Peng, Z H; Yang, W J; Cao, Y B; Yu, A M; Jin, Q H

2000-05-01

252

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

253

Ionized gas (plasma) delivery of reactive oxygen species (ROS) into artificial cells  

NASA Astrophysics Data System (ADS)

This study was designed to enhance our understanding of how reactive oxygen species (ROS), generated ex situ by ionized gas (plasma), can affect the regulation of signalling processes within cells. A model system, comprising of a suspension of phospholipid vesicles (cell mimics) encapsulating a ROS reporter, was developed to study the plasma delivery of ROS into cells. For the first time it was shown that plasma unequivocally delivers ROS into cells over a sustained period and without compromising cell membrane integrity. An important consideration in cell and biological assays is the presence of serum, which significantly reduced the transfer efficiency of ROS into the vesicles. These results are key to understanding how plasma treatments can be tailored for specific medical or biotechnology applications. Further, the phospholipid vesicle ROS reporter system may find use in other studies involving the application of free radicals in biology and medicine.

Hong, Sung-Ha; Szili, Endre J.; Jenkins, A. Toby A.; Short, Robert D.

2014-09-01

254

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

255

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

SciTech Connect

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

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

2014-03-28

256

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

257

Mechanisms of disruptions caused by noble gas injection into tokamak plasmas  

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

258

[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

259

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

E-print Network

in argon gas at atmospheric pressures Alexander Miloshevsky, Sivanandan S. Harilal, Gennady Miloshevsky formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures. VC plasma expansion into a background gas at atmospheric pressure is cru- cial for many engineering

Harilal, S. S.

260

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. PMID:23894232

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

2013-01-01

261

Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures  

NASA Astrophysics Data System (ADS)

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

Cremaschini, Claudio; Stuchlík, Zden?k

2014-04-01

262

Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures  

SciTech Connect

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

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

2014-04-15

263

Investigation of methods for sterilization of potting compounds and mated surfaces  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

264

Gas chromatographic-mass spectrometric determination of levodropropizine plasma levels in healthy volunteers.  

PubMed

A gas chromatographic-mass spectrometric method for the qualitative and quantitative analysis of levodropropizine (S(-)-3-(4-phenyl-piperazin-1-yl)-propane-1,2-diol, DF 526) in plasma is described. The method proved to be highly selective and sensitive. Drug concentrations as low as 5 ng/ml could be measured. Levodropropizine plasma levels were measured in 6 healthy volunteers after administration of an acute 60 mg dose. Peak concentrations were reached between 40 and 60 min and measurable amounts of drug were present till 8 h after administration. PMID:3196410

Zaratin, P; De Angelis, L; Cattabeni, F

1988-08-01

265

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

SciTech Connect

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

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

2009-09-30

266

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. PMID:24228085

2013-01-01

267

Stopping power of a buffer gas for laser plasma debris mitigation  

SciTech Connect

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

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

2009-12-15

268

[Determination of endogenous agmatine in rat plasma by isotope dilution-gas chromatography-mass spectrometry].  

PubMed

A method for the determination of endogenous agmatine in rat plasma was developed by isotope dilution-gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The plasma samples were analyzed after protein precipitation, evaporation, derivatization by hexafluoroacetone (HFAA), and clean-up on a Florisil SPE column. The GC-MS analysis utilized stable isotope d8-agmatine as internal standard. The samples after treatme were tested by negative chemical ionization with selected ion monitoring (SIM) which was set at m/z 492 (molecular ion of agmatine) and m/z 500 (molecular ion of internal standard). The limit of detection (LOD) of agmatine standard solution was 0.005 7 ng/mL. The calibration curve of the agmatine spiked in rat plasma showed a good linear relationship at the range of 1.14-57.0 ng/mL (r = 0.997). The recoveries of agmatine spiked in rat plasma ranged from 92.3% to 109.8%. Inter-day and intra-day precisions were less than 15%. The average concentration level of agmatine in rat plasma was (22 +/- 9) ng/mL, and there was no significant difference between male and female SD rats (p > 0.05). The method is high sensitive and specific, and can be used for the determination of endogenous agmatine in plasma. It provides a strong support for the subsequent research of agmatine. PMID:25255573

Qiu, Zhongli; Lin, Ying; Xiong, Zhili; Xie, Jianwei

2014-07-01

269

Plasma medicine  

Microsoft Academic Search

Different aspects of plasma medicine, the new branch interdisciplinary between plasma chemistry and medicine, are considered.\\u000a It was shown that complex biological processes in living tissues and bodies can be controlled, stimulated, catalyzed, and\\u000a diagnosed with the use of low-temperature, atmospheric-pressure air plasma. It was found that discharge plasma can produce\\u000a the desired therapeutic effect in wound sterilization and healing,

V. N. Vasilets; A. Gutsol; A. B. Shekhter; A. Fridman

2009-01-01

270

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

271

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

272

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

273

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

274

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. PMID:18701927

Bartz, Deborah; Greenberg, James A

2008-01-01

275

Start-phase ionization dynamics in the laser plasma at low gas target densities  

NASA Astrophysics Data System (ADS)

In Xe laser-produced-plasma sources of short-wave radiation, the laser-energy-to-EUV conversion efficiency (CE) proves substantially less than theoretical expectations. In the present work, a calculated estimate has been made which indicates that a long period of the primary ionization, lasting up to a moment when high-Z ions appear to emit short-wave photons, can be one of main causes for this. During that period the plasma remains low-ionized and absorbs weakly the laser energy. The estimate above has been experimentally confirmed with spectroscopic data and those on the effective ion charge derived from measured absorption of the laser radiation in the plasma. A preionization of the gas target with an ultraviolet (UV) excimer laser pulse is proposed as a method to accelerate the ionization process and consequently, to enhance CE.

Belik, V. P.; Demidov, R. A.; Kalmykov, S. G.; Mozharov, A. M.; Petrenko, M. V.; Sasin, M. E.

2013-12-01

276

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

SciTech Connect

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

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

2011-05-15

277

Determination of clemastine in human plasma by gas chromatography with nitrogen-phosphorus detection.  

PubMed

A method for the quantitative determination of clemastine in human plasma has been developed and validated. The assay uses gas chromatography with nitrogen-phosphorus detection and a HP-1 capillary column (25 mx0.22 mm, film thickness 0.33 mm) coated with dimethylpolysiloxane. Clemastine (with orphenadrine as internal standard) was isolated from human plasma using liquid-liquid extraction. A linear relationship was observed between 0.1 and 12.8 ng/ml using the peak area ratio of clemastine to orphenadrine with a correlation coefficient greater than 0.99 (the detection limit for clemastine was 0.06 ng/ml). The intra- and inter-day coefficients of variation were less than 11%. The developed method was used for the analysis of plasma samples from healthy volunteers (n = 19) to examine the pharmacokinetics of the antihistamine clemastine after single and multiple oral doses of clemastine fumarate. PMID:10985579

Davydova, N N; Yasuda, S U; Woosley, R L; Wainer, I W

2000-07-01

278

Closed cycle MHD generator with nonuniform gas-plasma flow driving recombinated plasma clots formed by high-energy electron beams  

SciTech Connect

A new concept of a closed cycle MHD generator without alkali seed has been suggested. The essence of it is the use of the high-energy electron beams technology for a nonuniform gas-plasma flow in MHD channel creation. At the inlet of MHD channel in supersonic flow of noble gas (He) the plasma clots with a density about 10{sup 15} cm{sup {minus}3} are formed by pulsed intense electron beams with energy about 100 keV. Gas flow drives these clots in a cross magnetic field along the MHD channel which has electrodes connected with a load by Faraday`s scheme. Because the nonuniform gas-plasma flow has not the conductivity in the Hall`s EMF direction a Faraday`s current can flow only through the narrow plasma layers. The energy dissipation and Joule`s heating in MHD channel support the nonequilibrium conductivity in these plasma layers. a gas flow pushes current layers and produces electric power at the expense of enthalpy extraction. The key element is a question of plasma layers stability in MHD channel. The most dangerous instability is the overheating instability. it is shown that taking into account the phenomenon of frozen conductivity for recombinated plasma which appears for noble gas at T{sub e} > 4,000 K the regime with {partial_derivative}{sigma}/{partial_derivative}T{sub e} < 0 can be realized. Due to the fulfillment of this condition the overheating instability is effectively suppressed. The numerical simulation has shown that a supersonic gas flow, containing about 4 current layers in MHD channel simultaneously, is braked without shock waves creation. Current layers provide no less than 30% enthalpy extraction and about 80% isentropic efficiency.

Danilov, V.V.; Laptev, S.S. [Krasnoyarsk State Univ. (Russian Federation); Slavin, V.S. [Krasnoyarsk State Technical Univ. (Russian Federation)

1996-12-31

279

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

280

Longitudinal gas-density profilometry for plasma-wakefield acceleration targets  

NASA Astrophysics Data System (ADS)

Precise tailoring of plasma-density profiles has been identified as one of the critical points in achieving stable and reproducible conditions in plasma wakefield accelerators. Here, the strict requirements of next generation plasma-wakefield concepts, such as hybrid-accelerators, with densities around 1017 cm-3 pose challenges to target fabrication as well as to their reliable diagnosis. To mitigate these issues we combine target simulation with fabrication and characterization. The resulting density profiles in capillaries with gas jet and multiple in- and outlets are simulated with the fluid code OpenFOAM. Satisfactory simulation results then are followed by fabrication of the desired target shapes with structures down to the 10 ?m level. The detection of Raman scattered photons using lenses with large collection solid angle allows to measure the corresponding longitudinal density profiles at different number densities and allows a detection sensitivity down to the low 1017 cm-3 density range at high spatial resolution. This offers the possibility to gain insight into steep density gradients as for example in gas jets and at the plasma-to-vacuum transition.

Schaper, Lucas; Goldberg, Lars; Kleinwächter, Tobias; Schwinkendorf, Jan-Patrick; Osterhoff, Jens

2014-03-01

281

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

PubMed

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

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

2014-07-01

282

Quantitative endogenous formate analysis in plasma using headspace gas chromatography without a headspace analyzer.  

PubMed

The objective was to develop a simple routine method for quantitative measurement of endogenous formic acid in plasma and whole blood using headspace gas chromatography-flame ionization detection. (GC-FID). Two-hundred microliters of sample was placed in a 1-mL glass vial. Fifty microliters of aqueous ethanol (10%) was added as an internal standard and a derivatizing agent. Ethylformate formation was enhanced by addition of 200 microL concentrated sulfuric acid as a catalyst. The vials were then sealed immediately and placed in a water bath for 15 min at 60 degrees C. One milliliter of this headspace gas was siphoned using a gas-tight syringe and injected into a GC-FID fitted with a capillary column. Ethanol eluted at approximately 3.0 min, and ethylformate eluted around 4.7 min. The limit of quantitation for ethylformate was 0.026 mmol/L, and the limit of detection was 0.020 mmol/L. Imprecisions for spiked plasma samples at 0.25 and 1 mmol/L were 10% and 9%, respectively and recoveries were at 100% and 108%, respectively. A simple, reliable, and highly specific headspace analysis method for quantifying endogenous formate without the use of a headspace analyzer was developed. This method enables the routine clinical analysis of formate in plasma and whole blood samples. PMID:17725880

Sokoro, AbdulRazaq; Lehotay, Denis; Eichhorst, Jeff; Treble, Ronald

2007-01-01

283

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

SciTech Connect

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

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

2013-02-07

284

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

285

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

NASA Astrophysics Data System (ADS)

In this study, a bipolar nanosecond pulse with 20 ns 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 390 K 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.

Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

2014-10-01

286

Voluntary sterilization in Flanders.  

PubMed

In a follow-up of males and females after voluntary sterilization, the social characteristics of the applicants, their fertility and contraceptive history, their motivations, the indication for and mode of surgical contraception, the physical and psychological consequences of the operation, and the outcome of the selection and counseling procedures applied, were studied in a sample of 275 applications with a total of 540 subjects. The survey comprised the preoperative examination, the 1st postoperative evaluation 4 months after surgery, and the 2nd after 12 months. The main reasons for applying for sterilization were excess fertility due to contraceptive failures and side-effects of reversible contraceptive methods. Almost all of the patients were satisfied with the operation, one of the highest proportions reported so far. Nevertheless, many experienced a real adjustment period. Notwithstanding the careful preoperative information and counseling, serious fears were often observed, and many found the operation more severe than expected. For the vast majority of the patients the operation had no influence on their family relations. The sexual relationship too was usually unchanged. If there were changes, the positive effects always exceeded the negative ones. The high response to both the evaluations and the high proportions of satisfied individuals are in favor of the selection procedures and multidisciplinary counseling and follow-up practiced. PMID:7462268

Cliquet, R L; Thiery, M; Staelens, R; Lambert, G

1981-01-01

287

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

288

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

SciTech Connect

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. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Ostrikov, K. [CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070 (Australia); School of Physics, University of Sydney, Sydney NSW 2006 (Australia); State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2013-02-15

289

9 CFR 109.2 - Sterilizers.  

Code of Federal Regulations, 2010 CFR

...INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STERILIZATION AND PASTEURIZATION AT LICENSED ESTABLISHMENTS § 109.2 Sterilizers. Steam and dry-heat sterilizers used...

2010-01-01

290

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

SciTech Connect

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

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

2011-05-20

291

Sterilization of Extracted Human Teeth.  

ERIC Educational Resources Information Center

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

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

1990-01-01

292

Effect of various sterilization methods on the bioactivity of laser ablation pseudowollastonite coating.  

PubMed

Sterilization is required for using any material or device in contact with the human body. The aim of this work was to investigate the effect of four sterilization methods (steam autoclave, hydrogen peroxide plasma, ethylene oxide, and gamma sterilization) on the surface chemistry and in vitro bioactivity of pseudowollastonite (psW) coatings in titanium alloys substrates. psW coatings in Ti-6Al-4V substrates obtained by laser ablation technique were sterilized and immersed in Kokubo's simulated body fluid (SBF) up to 30 days. No changes in the chemical composition were noted after sterilization. However, a Ca/P-layer of different thickness, identified as hydroxyapatite (HA) like was developed on all the samples after soaking, although, the ethylene oxide sterilized samples present a nonhomogeneous and approximately 55.9% thinner HA-like layer. PMID:20578226

Zuleta, F A; Velasquez, P; De Aza, P N

2010-08-01

293

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

PubMed

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

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

2014-10-21

294

The Neutral Gas Desorption and Breakdown on a Metal-Dielectric Junction Immersed in a Plasma  

NASA Technical Reports Server (NTRS)

New results are presented of an experimental study and theoretical analysis of arcing on metal-dielectric junctions immersed in a low-density plasma. Two samples of conventional solar arrays have been used to investigate the effects of arcing within a wide range of neutral gas pressures, ion currents, and electron number densities. All data (except video) were obtained in digital form that allowed us to study the correlation between external parameters (plasma density, additional capacitance, bias voltage, etc) and arc characteristics (arc rate, arc current pulse width and amplitude, gas species partial pressures, intensities of spectral lines, and so on). Arc sites were determined by employing a video-camera, and it is shown that the most probable sites for arc inception are trip le-junctions, even though some arcs were initiated in gaps between cells. The effect of surface conditioning (decrease of arc rate due to outgassing) was clearly demonstrated. Moreover, a considerable increase in arc rate due to absorption of molecules from atmospheric air has been confirmed. The analysis of optical spectra (240-800 nm) reveals intense narrow atomic lines (Ag, H) and wide molecular bands (OH, CH, SiH, SiN) that confirm a complicated mechanism of arc plasma generation. The rate of plasma contamination due to arcing was measured by employing a mass-spectrometer. These measurements provided quite reliable data for the development of a theoretical model of plasma contamination, In conclusion, the arc threshold was increased to above 350 V (from 190 V) by keeping a sample in vacuum (20 micronTorr) for seven days. The results obtained are important for the understanding of the arc inception mechanism, which is absolutely essential for progress toward the design of high voltage solar arrays for space applications.

Vayner, Boris; Galofaro, Joel; Ferguson, Dale; Lyons, Valerie J. (Technical Monitor)

2002-01-01

295

Sterile neutrinos: Phenomenology and theory  

NASA Astrophysics Data System (ADS)

A simultaneous understanding of the results of the LSND experiment indicating ??-?e oscillation together with other evidences for neutrino oscillations from solar and atmospheric neutrino data seems to require the existence of at least one sterile neutrino. One can also give other plausible astrophysical arguments that seem to require light sterile neutrinos. If such sterile neutrinos exist, a major theoretical challenge is to understand why they are so light. A scenario for the light sterile neutrino is presented where one assumes a parity doubling of the standard model with identical matter and gauge content. The neutrinos of the parity doubled (mirror) sector are light for the same reason that the known neutrinos are light and since they do not couple to the known W and Z bosons, they can be identified with the sterile neutrinos. Some of the implications and possible tests of this hypothesis are mentioned.

Mohapatra, Rabindra N.

1999-07-01

296

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

Microsoft Academic Search

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

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

2003-01-01

297

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

SciTech Connect

Experimental results indicate deceleration of the detonation wave under conditions of partial absorption of laser radiation when both plasmas--detonation wave and ablation plasma--are ignited simultaneously. The observed effect is attributed to a reduction of laser radiation intensity, reflected by the target surface and transmitted back to the detonation wave, due to the absorption in the dense ionized vapor of the target material. Also, we report results of studies on dynamics of axial and radial shock waves formed in a gas during propagation of the detonation wave. The observed differences between experimental results and self-similar computations are attributed to the effect of the hot gas transfer along the laser beam axis out of the zone of absorption of laser radiation. All the experiments were performed using carbon-dioxide laser with pulse width of a few microseconds and energy of 1 J. We employed streak camera, fast diodes, CCD camera imaging, and plasma transparency measurement techniques for data acquisition.

Anisimov, Vladimir N.; Grishina, Valeria G.; Derkach, Oleg N.; Malyta, Dmitry D.; Sebrant, Andrey Y. [Institute of Laser Physics, National Research Center-Kurchatov Institute, Kurchatov Square, Moscow, 123098 (Russian Federation)

1997-04-15

298

[Principles of antisepsis, disinfection and sterilization].  

PubMed

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

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

2014-12-01

299

An enhanced plasma-catalytic method for DeNO(x) in simulated flue gas at room temperature.  

PubMed

A combined adsorption-discharge plasma process was proposed for DeNOx in simulated flue gas at room temperature. The conversion of NOx to N2 could achieve 95% in the process of NOx storage and reduction with NH3 under simulated flue gas conditions. PMID:24003442

Wang, Hui; Li, Xiangxiang; Chen, Ping; Chen, Min; Zheng, Xiaoming

2013-10-18

300

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

301

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

302

Nonlinear oscillations of gas bubbles submerged in water: implications for plasma breakdown  

NASA Astrophysics Data System (ADS)

Gas bubbles submerged in a dielectric liquid and driven by an electric field can undergo dramatic changes in both shape and volume. In certain cases, this deformation can enhance the distribution of the applied field inside the bubble as well as decrease the internal gas pressure. Both effects will tend to facilitate plasma formation in the gas volume. A practical realization of these two effects could have a broad impact on the viability of liquid plasma technologies, which tend to suffer from high voltage requirements. In this experiment, bubbles of diameter 0.4-0.7 mm are suspended in the node of a 26.4 kHz underwater acoustic standing wave and excited into nonlinear shape oscillations using ac electric fields with amplitudes of 5-15 kV cm-1. Oscillations of the deformed bubble are photographed with a high-speed camera operating at 5130 frames s-1 and the resulting images are decomposed into their axisymmetric spherical harmonic modes, Y_l^0 , using an edge detection algorithm. Overall, the bubble motion is dominated by the first three even modes l = 0, 2 and 4. Electrostatic simulations of the deformed bubble's internal electric field indicate that the applied field is enhanced by as much as a factor of 2.3 above the nominal applied field. Further simulation of both the pure l = 2 and l = 4 modes predicts that with additional deformation, the field enhancement factors could reach as much as 10-50.

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

2012-10-01

303

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

304

Influence of Gas Entry Point on Plasma Chemistry, Ion Energy and Deposited Alumina Thin Films in Filtered Cathodic Arc  

Microsoft Academic Search

The effect of gas entry point on the plasma chemistry, ion energy distributions and resulting alumina thin film growth have\\u000a been investigated for a d.c. cathodic arc with an aluminum cathode operated in an oxygen\\/argon atmosphere. Ions of aluminum,\\u000a oxygen and argon, as well as ions originating from the residual gas are investigated, and measurements for gas entry at both

J. Rosen; P. O. Å. Persson; M. Ionescu; J. Pigott; D. R. McKenzie; M. M. M. Bilek

2007-01-01

305

Inductively Coupled Plasma Etching of Silicon Using Solid Iodine as an Etching Gas Source  

NASA Astrophysics Data System (ADS)

We investigated the Si dry etching process by inductively coupled plasma (ICP) using solid I2 as an etching gas source. A vertical etching profile and a smooth etched surface, which satisfy the requirements for optical device fabrication, were obtained at a relatively higher substrate temperature. The etching rate of Si was approximately 90 nm/min at 1 Pa and at an ICP/bias RF power of 300/100 W. The I2 plasma etching technique is a very simple C-, CF-, and H-free process. In addition, we believe that this proposed process is useful for fabricating Si-based optical devices, such as photonic crystals, narrow optical waveguides, and micro-electro-mechanical systems (MEMS).

Matsutani, Akihiro; Ohtsuki, Hideo; Koyama, Fumio

2011-06-01

306

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

307

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

308

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. PMID:17651558

Levy, Jenna; Childers, Meredith E.

2007-01-01

309

Optimization of moist heat sterilization.  

PubMed

The use of different combinations of sterilization time and temperature in a pilot scale autoclave, GEV 612 AR-2 (Getinge Ab, Sweden), in optimizing the sterilization process was studied. All three programs used had the same sterilization efficacy (F0 = 15 minutes) but different sterilization temperatures (116, 121, and 126 degrees C) and total process times (98, 57, and 44 minutes). The heat distribution during the sterilization phase was, in all cases, very uniform, the greatest difference being 0.5 degrees C. Also the F0 values differed only by +/- 0.5 minutes from each other. The F0 value increases linearly with all programs until the beginning of the cooling phase. The main effect of different sterilization temperatures on the cumulative F0 curves is an increase in the slope of the curves with increasing sterilization temperature. First order temperature change constants were determined both for the heating phase and the cooling phase. The numeric values of the rate constants for the heating and the cooling phases were 0.20 +/- 0.03 and 0.046 +/- 0.005 min-1, respectively. It is concluded that the pilot autoclave used in this study controls the sterilization process very accurately. The observed variations between F0 values at different positions in the autoclave chamber are acceptable. On the basis of this study an accurately engineered and controlled autoclave is required in process optimization. It also is possible to use higher sterilization temperatures than usually suggested in pharmacopeias and thus to shorten the process time. PMID:8120736

Mannermaa, J P; Yliruusi, J

1993-01-01

310

Optical diagnostics of a low power—low gas flow rates atmospheric-pressure argon plasma created by a microwave plasma torch  

NASA Astrophysics Data System (ADS)

We employ a suite of optical techniques, namely, visual imaging, optical emission spectroscopy and cavity ringdown spectroscopy (CRDS), to characterize a low power, low gas flow rates, atmospheric-pressure argon microwave induced plasma. The plasma is created by a microwave plasma torch, which is excited by a 2.45 GHz microwave with powers ranging from 60 to 120 W. A series of plasma images captured in a time-resolution range of as fine as 10 µs shows that the converging point is actually a time-averaged visual effect and the converging point does not exist when the plasma is visualized under high time resolution, e.g. <2 ms. Simulations of the emission spectra of OH, N2 and N_{2}^{+} in the range 200-450 nm enable the plasma electronic excitation temperature (Texc) to be determined at 8000-9000 K, while the vibrational temperature (Tv), the rotational temperature (Tr) and the gas temperature (Tg) at different locations along the axis of the plasma column are all determined to be in the range 1800-2200 K. Thermal equilibrium properties of the plasma are discussed. OH radical concentrations along the plasma column axis are measured by CRDS and the concentrations are in the range 1.6 × 1013-3.0 × 1014 cm-3 with the highest density at the tail of the plasma column. The upper limit of electron density ne is estimated to be 5.0 × 1014 cm-3 from the Lorentzian component of the broadened lineshape obtained by ringdown spectral scans of the rovibrational line S21 of the OH A-X (0-0) band.

Wang, Chuji; Srivastava, Nimisha; Scherrer, Susan; Jang, Ping-Rey; Dibble, Theodore S.; Duan, Yixiang

2009-05-01

311

MINOS Search for Sterile Neutrinos  

E-print Network

Using a NuMI beam exposure of 7.1 /times 10^20 protons-on-target, the MINOS long-baseline experiment has performed a search for active to sterile neutrino mixing over a distance of 735 km. Details of the analysis are provided, along with results from comparisons with standard three neutrino oscillations and fits to a 3+1 model including oscillations into one sterile neutrino. An outlook on the future sterile neutrino related contributions from MINOS and the proposed MINOS+ project is also presented.

Alexandre Sousa; on behalf of the MINOS Collaboration

2011-10-16

312

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

313

Sensitive assay of methadone in plasma by using capillary gas chromatography with photoionization detection.  

PubMed

A new gas chromatographic assay for methadone, utilizing a fused-silica capillary column, is presented. Extreme sensitivity was reached, compared to nitrogen-phosphorus and mass spectrometry detection, by employing a photoionization detector. Plasma concentrations of methadone as low as 1 ng/ml can easily be detected and, by further optimization, 0.1 ng/ml was reached. The minimum detectable amount of methadone reaching the detector was 70 fg. The results indicate that the photoionization detector has potential as a tool in drug monitoring. PMID:3700556

Norlander, B; Carlsson, B; Bertler, A

1986-03-01

314

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

315

Production of ultra clean gas-atomized powder by the plasma heated tundish technique  

SciTech Connect

The paper describes the improvements in cleanliness for different types of gas atomized powders produced by holding the melt in a Plasma Heated Tundish (PHT) before atomization. The cleanliness is measured on Hot Isostatically Pressed (HIP) or extruded samples. Significant improvements in slag levels and material properties have been achieved. On extruded powder metallurgy stainless steel and nickel alloy tubes, the rejection rate in ultra-sonic testing was reduced drastically. Tool steels and high speed steels have greatly improved ductility and bend strength.

Tingskog, T.A. [Anval Inc., Rutherford, NJ (United States); Andersson, V. [Anval Nyby Powder A.B., Torshalla (Sweden)

1996-12-31

316

IOP PUBLISHING PLASMA SOURCES SCIENCE AND TECHNOLOGY Plasma Sources Sci. Technol. 20 (2011) 035018 (8pp) doi:10.1088/0963-0252/20/3/035018  

E-print Network

applications of APPs is sterilization and disinfection [13]. The causes of bacteria killing by plasmas, in the case of bacteria, the plasma's sterilization capability. In this paper, we discuss results from is the plasma sterilization of air by killing floating bacteria. Topologically, bacteria floating in air being

Kushner, Mark

317

Laser induced aluminiun plasma analysis by optical emission spectroscopy in a nitrogen background gas  

NASA Astrophysics Data System (ADS)

We studied an Al plasma generated by a Nd:YAG laser with a laser fluence of 4 J/cm2, a wavelength of 1064 nm, energy pulse of 500 mJ and 10 Hz repetition rate. We studied their spectral characteristics at various ambient nitrogen pressures by optical emission spectroscopy (OES). The N2 gas pressure was varied from 20 mTorr to 150 mTorr. In Al plume, both atomic and ionic spectra were observed. The electron temperature and electron number density of the plume as of the function ambient gas pressure were determined. The electron temperature was calculated by using the Boltzmann-plot method and the number density was calculated considering the stark effect as dominating on the emission lines.

Chamorro, J. C.; Uzuriaga, J.; Riascos, H.

2012-06-01

318

Production of synthesis gas by conversion of methane in a steam-carbon dioxide plasma  

NASA Astrophysics Data System (ADS)

Experimental setup and results of methane conversion in a steam-carbon dioxide plasma are briefly described. Mass-flow rate of CH4 was varied from 2.5 to 3.7 g/s while mass-flow rates of H2O of ˜3 g/s and CO2 of ˜3 g/s were maintained constant. The energy consumption was 29-42 MJ per 1 kg of CH4. The H2/CO ratio in the produced synthesis gas was 2.2-2.4. The conversion rate of CH4 was 90.8-99.8%. The content of H2 and CO in the synthesis gas was ˜95%.

Rutberg, Ph. G.; Bratsev, A. N.; Kuznetsov, V. A.; Nakonechnyi, G. V.; Nikonov, A. V.; Popov, V. E.; Popov, S. D.; Serba, E. O.; Subbotin, D. I.; Surov, A. V.

2014-09-01

319

Signature of superradiance from a nitrogen gas plasma channel produced by strong field ionization  

E-print Network

Recently, Yao et al. demonstrated the creation of coherent emissions in nitrogen gas with two-color (800 nm + 400 nm) ultrafast laser pulses [New J. Phys. 15, 023046 (2013)]. Based on this two-color scheme, here we report on systematic investigation of temporal characteristics of the coherent emission at 391 nm by experimentally examining its evolution with the increase of the plasma channel induced by the intense 800 nm femtosecond laser pulses at a nitrogen gas pressure of ~25 mbar. We reveal unexpected temporal profiles of the coherent emissions, which show significant superradiance signatures owing to the quantum coherence via cooperation of an ensemble of excited N2+ molecules. Our findings shed more light on the mechanisms behind the laser-like emissions induced by strong-field ionization of molecules.

Li, Guihua; Zeng, Bin; Xie, Hongqiang; Yao, Jinping; Chu, Wei; Ni, Jielei; Zhang, Haisu; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

2013-01-01

320

Steam Sterilization of Cordless Surgical Instruments  

Microsoft Academic Search

This project was undertaken to evaluate the effectiveness of different sterilization procedures on a new line of cordless surgical drills and driver\\/reamers which have recently come onto the commercial market. The procedures include both conventional and flash steam sterilization protocols. The study demonstrated that the new line of cordless instruments can be easily and quickly sterilized by normal hospital sterilization

Dezso K. Merenyi; Lucy Brown; Neil S. Rothman; Robert Austin Milch; Edward M. Soffen

1981-01-01

321

In situ gas-phase hydrosilylation of plasma-synthesized silicon nanocrystals.  

PubMed

Surface passivation of semiconductor nanocrystals (NCs) is critical in enabling their utilization in novel optoelectronic devices, solar cells, and biological and chemical sensors. Compared to the extensively used liquid-phase NC synthesis and passivation techniques, gas-phase routes provide the unique opportunity for in situ passivation of semiconductor NCs. Herein, we present a method for in situ gas-phase organic functionalization of plasma-synthesized, H-terminated silicon (Si) NCs. Using real-time in situ attenuated total reflection Fourier transform IR spectroscopy, we have studied the surface reactions during hydrosilylation of Si NCs at 160 °C. First, we show that, during gas-phase hydrosilylation of Si NCs using styrene (1-alkene) and acetylene (alkyne), the reaction pathways of the alkenes and alkynes chemisorbing onto surface SiH(x) (x = 1-3) species are different. Second, utilizing this difference in reactivity, we demonstrate a novel pathway to enhance the surface ligand passivation of Si NCs via in situ gas-phase hydrosilylation using the combination of a short-chain alkyne (acetylene) and a long-chain 1-alkene (styrene). The quality of surface passivation is further validated through IR and photoluminescence measurements of Si NCs exposed to air. PMID:21774486

Jariwala, Bhavin N; Dewey, Oliver S; Stradins, Paul; Ciobanu, Cristian V; Agarwal, Sumit

2011-08-01

322

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

323

Local demands on sterile neutrinos  

E-print Network

In a model independent manner, we explore the local implications of a single neutrino oscillation measurement which cannot be reconciled within a three-neutrino theory. We examine this inconsistency for a single region of baseline to neutrino energy $L/E$. Assuming that sterile neutrinos account for the anomaly, we find that the {\\it local} demands of this datum can require the addition to the theory of one to three sterile neutrinos. We examine the constraints which can be used to determine when more than one neutrino would be required. The results apply only to a given region of $L/E$. The question of the adequacy of the sterile neutrinos to satisfy a global analysis is not addressed here. Finally, using the results of a 3+2 analysis, we indicate values for unknown mixing matrix elements which would require two sterile neutrinos due to local demands only.

David C. Latimer; David J. Ernst

2005-09-23

324

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

E-print Network

source based on pulsed plasma sputtering for the synthesis of PtX catalytic nanoclusters A. Caillard(*)1, structure and size) of these catalytic NCs must be well controlled in order to promote their catalytic pressure, PtX NCs are formed. They are ejected from the GAS through a 4 mm in diameter aperture and land

Paris-Sud XI, Université de

325

Food irradiation and sterilization  

NASA Astrophysics Data System (ADS)

Radiation sterilization of food (radappertization) requires exposing food in sealed containers to ionizing radiation at absorbed doses high enough (25-70 kGy) to kill all organisms of food spoilage and public health significance. Radappertization is analogous to thermal canning is achieving shelf stability (long term storage without refrigeration). Except for dry products in which autolysis is negligible, the radappertization process also requires that the food be heated to an internal temperature of 70-80°C (bacon to 53°C) to inactivate autolytic enzymes which catalyze spoilage during storage without refrigeration. To minimize the occurence of irradiation induced off-flavors and odors, undesirable color changes, and textural and nutritional losses from exposure to the high doses required for radappertization, the foods are vacuum sealed and irradiated frozen (-40°C to -20°C). Radappertozed foods have the characteristic of fresh foods prepared for eating. Radappertization can substitute in whole or in part for some chemical food additives such as ethylene oxide and nitrites which are either toxic, carcinogenic, mutagenic, or teratogenic. After 27 years of testing for "wholesomeness" (safety for consumption) of radappertized foods, no confirmed evidence has been obtained of any adverse effecys of radappertization on the "wholesomeness" characteristics of these foods.

Josephson, Edward S.

326

Plasma jets and plasma bullets  

Microsoft Academic Search

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma

M G Kong; B N Ganguly; R F Hicks

2012-01-01

327

Restrictions on the lifetime of sterile neutrinos from primordial nucleosynthesis  

SciTech Connect

We analyze the influence of sterile neutrinos with the masses in the MeV range on the primordial abundances of Helium-4 and Deuterium. We solve explicitly the Boltzmann equations for all particle species, taking into account neutrino flavour oscillations and demonstrate that the abundances are sensitive mostly to the sterile neutrino lifetime and only weakly to the way the active-sterile mixing is distributed between flavours. The decay of these particles also perturbs the spectra of (decoupled) neutrinos and heats photons, changing the ratio of neutrino to photon energy density, that can be interpreted as extra neutrino species at the recombination epoch. We derive upper bounds on the lifetime of sterile neutrinos based on both astrophysical and cosmological measurements of Helium-4 and Deuterium. We also demonstrate that the recent results of Izotov and Thuan [1], who find 2? higher than predicted by the standard primordial nucleosynthesis value of Helium-4 abundance, are consistent with the presence in the plasma of sterile neutrinos with the lifetime 0.01–2 seconds.

Ruchayskiy, Oleg [Physics Department, Theory Division, CERN, CH-1211 Geneva 23 (Switzerland); Ivashko, Artem, E-mail: oleg.ruchayskiy@epfl.ch, E-mail: ivashko@lorentz.leidenuniv.nl [Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, Niels Bohrweg 2, Leiden (Netherlands)

2012-10-01

328

Quantitation by Gas Chromatography-Chemical lonization- Mass Spectrometry of Phenylalanine Mustard in Plasma of Patients1  

Microsoft Academic Search

An unambiguous and sensitive method based on gas chro- matography-chemical ionization-mass spectrometry has been developed to quantitate L-phenylalanine mustard and has been applied to measure levels in plasma of five patients receiving 0.15 to 0.25 mg\\/kg (10 to 17 mg) of the drug p.o. Peak plasma levels of 50 to 190 ng\\/ml were found to occur between 0.7 and 2.3

Sharon L. Pallante; Catherine Fenselau; Robert G. Mennel; Robert B. Brundrett; Mark Appier; Neil B. Rosenshein; Michael Colvin

329

Influence of gas puff location on the coupling of lower hybrid waves in JET ELMy H-mode plasmas  

SciTech Connect

Reliable coupling of the lower hybrid current drive (LHCD) to H-mode plasmas in JET is made feasible through a dedicated gas injection system, located at the outer wall and magnetically connected to the antenna (Pericoli Ridolfini et al 2004 Plasma Phys. Control. Fusion 46 349, Ekedahl et al 2005 Nucl. Fusion 45 351, Ekedahl et al 2009 Plasma Phys. Control. Fusion 51 044001). An experiment was carried out in JET in order to investigate whether a gas injection from the top of the torus, as is foreseen for the main gas injection in ITER, could also provide good coupling of the LH waves if magnetically connected to the antenna. The results show that a top gas injection was not efficient for providing a reliable LHCD power injection, in spite of being magnetically connected and in spite of using almost twice the amount of gas flow compared with the dedicated outer mid-plane gas puffing system. A dedicated gas injection system, set in the outer wall and magnetically connected to the LHCD antenna, is therefore recommended in order to provide the reliable coupling conditions for an LHCD antenna in ITER.

Ekedahl, A. [CEA, IRFM, France; Petrzilka, V. [Assoc. Euratom-IPP.CR, Czech Republic; Baranov, Y. [EURATOM / UKAEA, UK; Brix, M [UKAEA Fusion, Culham UK; Goniche, M. [CEA, IRFM, France; Jacquet, P. [EURATOM / UKAEA, Abingdon, UK; Kirov, K K [Association EURATOM-CCFE, Abingdon, UK; Klepper, C Christopher [ORNL; Mailloux, J. [EURATOM / UKAEA, UK; Mayoral, M.-L. [EURATOM / UKAEA, UK; Nave, M. F. F. [Association EURATOM/IST, Lisbon, Portugal; Ongena, J. [Laboratory for Plasma Physics-ERM/KMS (LPP-ERM/KMS), Brussels, Belgium

2012-01-01

330

Genomic Networks of Hybrid Sterility  

PubMed Central

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.

2014-01-01

331

X-ray imaging of uniform large scale-length plasmas created from gas-filled targets on Nova  

SciTech Connect

We report on the production and characterization of large scale-length plasmas created by illuminating gas-filled thin-walled balloon-like targets using the Nova laser. The targets consisted of a 4--5000 {angstrom} skin surrounding 1 atm of neopentane which when ionized becomes a plasma with 10{sup 21} electrons/cm{sup 3}. Results are presented from x-ray imaging used to evaluate the uniformity of the plasma. The most uniform plasmas were produced by illuminating the target with large converging beams that overlapped to cover most of the surface of the gasbag. An alternate focus geometry using small beam spots resulted in a less uniform plasma with low density holes in it.

Kalantar, D.H.; MacGowan, B.J.; Bernat, T.P. [and others

1994-05-01

332

The limits of sterility assurance.  

PubMed

Sterility means the absence of all viable microorganisms including viruses. At present, a sterility assurance level (SAL) of 10(-6) is generally accepted for pharmacopoeial sterilization procedures, i.e., a probability of not more than one viable microorganism in an amount of one million sterilised items of the final product. By extrapolating the reduction rates following extreme artificial initial contamination, a theoretical overall performance of the procedure of at least 12 lg increments (overkill conditions) is demanded to verify an SAL of 10(-6). By comparison, other recommendations for thermal sterilization procedures demand only evidence that the difference between the initial contamination and the number of test organisms at the end of the process amount to more than six orders of magnitude. However, a practical proof of the required level of sterility assurance of 10(-6) is not possible. Moreover, the attainability of this condition is fundamentally dubious, at least in non-thermal procedures. Thus, the question is discussed whether the undifferentiated adherence to the concept of sterility assurance on the basis of a single SAL of 10(-6) corresponds with the safety requirements in terms of patient or user safety, costs and energy efficiency. Therefore, in terms of practical considerations, a concept of tiered SALs is recommended, analogous to the comparable and well-established categorization into "High-level disinfection", "Intermediate-level disinfection" and "Low-level disinfection". The determination of such tiered SALs is geared both to the intended application of the sterilized goods, as well as to the characteristics of the products and the corresponding treatment options.In the case of aseptic preparation, filling and production procedures, a mean contamination probability of 10(-3) is assumed. In automated processes, lower contamination rates can be realized. In the case of the production of re-usable medical devices, a reduction of at least 2 lg increments can be achieved through prior cleaning in validated cleaning and disinfecting devices. By chemical disinfection, a further reduction of >/=5 lg increments is achieved. In the case of sterilized surgical instruments, an additional concern is that they lay opened in contaminated air for the duration of the operation, at least in conventionally ventilated operating theaters. Finally, the amount of pathogens necessary to cause an infection must be considered. By logical consideration of all aspects, it seems possible to partially reduce sterility assurance levels without any loss of safety. Proceeding from this, we would like to make the following suggestions for tiered SAL values, adjusted according to the respective sterilization task:SAL 10(-6) for heat-resistant pharmaceutical preparations (parenterals), suggested term: "Pharmaceutical sterilization",SAL 10(-4) for heat-resistant medical devices, suggested term: "High-level sterilization",SAL 10(-3) for heat-sensitive re-usable medical devices, under the precondition of a validated cleaning efficacy of >4 lg increments, suggested term: "Low-level sterilization". PMID:20204091

von Woedtke, Thomas; Kramer, Axel

2008-01-01

333

REVIEW ARTICLE: Modelling of thermal plasmas for arc welding: the role of the shielding gas properties and of metal vapour  

Microsoft Academic Search

The methods used to model thermal plasmas, including treatments of diffusion in arcs in gas mixtures, are reviewed. The influence of thermophysical properties on the parameters of tungsten-inert-gas (TIG) welding arcs, particularly those that affect the weld pool, is investigated using a two-dimensional model in which the arc, anode and cathode are included self-consistently. The effect of changing each of

A. B. Murphy; M. Tanaka; K. Yamamoto; S. Tashiro; T. Sato; J. J. Lowke

2009-01-01

334

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

SciTech Connect

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

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

2012-06-18

335

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

336

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Intense charge exchange of laser-plasma ions with the atoms of a pulsed gas jet  

NASA Astrophysics Data System (ADS)

The results of experiments on the interaction of a laser plasma with a pulsed gas jet are presented. The charge exchange of ions with neutral particles was realised for the first time under controllable conditions for a density of the reagents of no less than 1016 cm-3. The resonance pumping of the C3+ ion level with n=3 was observed by spectral methods. The structure of the region of intense charge exchange was determined from plasma photographs. The data obtained suggest that experiments on soft X-ray lasing at a C5+ ion transition are promising.

Antonov, V. M.; Boyarintsev, Y. L.; Melekhov, A. V.; Posukh, V. G.; Ponomarenko, A. G.; Shaikhislamov, I. F.

2007-09-01

337

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

NASA Technical Reports Server (NTRS)

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

Thom, Karlheinz; Norwood, Joseph, Jr.

1961-01-01

338

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

SciTech Connect

We investigated the effect of helium and nitrogen pressures on the dynamics of molecular species formation during laser ablation of carbon. For producing plasmas, planar carbon targets were irradiated with 1064 nm, 6 ns pulses from an Nd:yttrium aluminum garnet laser. The emission from excited C{sub 2} and CN molecules was studied using space resolved optical time-of-flight emission spectroscopy and spectrally resolved fast imaging. The intensity oscillations in C{sub 2} and CN monochromatic fast imaging and their emission space-time contours suggest that recombination is the major mechanism of C{sub 2} formation within the laser ablation carbon plumes in the presence of ambient gas.

Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.

2011-09-26

339

Elemental speciation analysis by multicapillary gas chromatography with microwave-induced plasma atomic spectrometric detection.  

PubMed

Multicapillary column gas chromatography (MC-GC)/microwave-induced plasma atomic emission spectrometry (MIP AES) was developed for fast speciation analysis of organotin compounds in the environment. Ethylated butyltin compounds could be separated isothermally within less than 30 s (instead of ?5-10 min) without sacrificing either the resolution or the sample capacity of conventional capillary GC with oven temperature gradient programming. Careful optimization of the pressure and temperature GC program allowed a comprehensive organotin speciation analysis including phenyltin compounds within less than 2.5 min, increasing the sample throughput 6-fold. Compatibility of MC-GC with an MIP atomic emission detector (MIP-AED) was discussed. MC-GC/MIP-AES was validated for the analysis of sediment (PACS-1 and BCR 462) and biological (NIES11) certified reference materials. PMID:21639152

Rodriguez Pereiro, I; Schmitt, V O; Lobi?ski, R

1997-12-01

340

ELSEVIER Diamond and Related Materials 4 (1995) 1000-1008 Dependence of the gas composition in a microwave plasma-assisted  

E-print Network

ELSEVIER Diamond and Related Materials 4 (1995) 1000-1008 EiAMOND RELATED MATERIALS Dependence of the gas composition in a microwave plasma-assisted diamond chemical vapor deposition reactor on the inlet spectrometry was used to measure the gas-phase composition near a growing diamond surface in a microwave plasma

Dandy, David

341

Development of a plasma sprayed ceramic gas path seal for high pressure turbine application  

NASA Technical Reports Server (NTRS)

Development of the plasma sprayed graded, layered ZRO2/CoCrAlY seal system for gas turbine engine blade tip seal applications up to 1589 K (2400 F) surface temperature was continued. The effect of changing ZRO2/CoCrAlY ratios in the intermediate layers on thermal stresses was evaluated analytically with the goal of identifying the materials combinations which would minimize thermal stresses in the seal system. Three methods of inducing compressive residual stresses in the sprayed seal materials to offset tensile thermal stresses were analyzed. The most promising method, thermal prestraining, was selected based upon potential, feasibility and complexity considerations. The plasma spray equipment was modified to heat, control and monitor the substrate temperature during spraying. Specimens were fabricated and experimentally evaluated to: (1) substantiate the capability of the thermal prestrain method to develop compressive residual stresses in the sprayed structure and (2) define the effect of spraying on a heated substate on abradability, erosion and thermal shock characteristics of the seal system. Thermal stress analysis, including residual stresses and material properties variations, was performed and correlated with thermal shock test results. Seal system performance was assessed and recommendations for further development were made.

Shiembob, L. T.

1978-01-01

342

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

PubMed

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

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

2014-10-20

343

Fabrication of gas turbine water-cooled composite nozzle and bucket hardware employing plasma spray process  

DOEpatents

In the method for fabrication of water-cooled composite nozzle and bucket hardware for high temperature gas turbines, a high thermal conductivity copper alloy is applied, employing a high velocity/low pressure (HV/LP) plasma arc spraying process, to an assembly comprising a structural framework of copper alloy or a nickel-based super alloy, or combination of the two, and overlying cooling tubes. The copper alloy is plamsa sprayed to a coating thickness sufficient to completely cover the cooling tubes, and to allow for machining back of the copper alloy to create a smooth surface having a thickness of from 0.010 inch (0.254 mm) to 0.150 inch (3.18 mm) or more. The layer of copper applied by the plasma spraying has no continuous porosity, and advantageously may readily be employed to sustain a pressure differential during hot isostatic pressing (HIP) bonding of the overall structure to enhance bonding by solid state diffusion between the component parts of the structure.

Schilke, Peter W. (4 Hempshire Ct., Scotia, NY 12302); Muth, Myron C. (R.D. #3, Western Ave., Amsterdam, NY 12010); Schilling, William F. (301 Garnsey Rd., Rexford, NY 12148); Rairden, III, John R. (6 Coronet Ct., Schenectady, NY 12309)

1983-01-01

344

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

PubMed

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

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

2014-06-10

345

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 PMID:4977644

Songer, J. R.; Mathis, R. G.

1969-01-01

346

Plasma discharge and time-dependence of its effect to bacteria.  

PubMed

Several types of plasma discharge have been proven to have a capacity for sterilization. Our goal is to introduce new nonthermal plasma pencil. We used it to sterilize different microbial populations with differing ages. We used a plasma discharge of the following characteristics: radio frequency barrier discharger at atmospheric pressure with a working frequency of 13.56 MHz, and the working gas used was argon. We performed 110 tests with the following microbial populations: Pseudomonas aeruginosa, Staphylococcus aureus, Proteus species, and Klebsiella pneumoniae. All populations were inoculated on the previous day and also on the day of our experiment. We made our evaluations the following day and also after 5 days, with all our microbial populations. Eradication of microbial populations is dependent on the plasma discharge exposure time in all cases. With regard to freshly inoculated microbes, we were able to sterilize agar with intensive exposure lasting for 10 s of colonies Pseudomonas, Proteus, and Klebsiella. The most resistant microbe seems to be S. aureus, which survives 5 s of coherent exposure in half of the cases. Using the lightest plasma discharge exposure, we achieved a maximum of 10(4)-10(5) CFU/mL (colony-forming unit - CFU). Regarding older microbial populations inoculated the day before the experiment, we can only decrease population growth to 10(5) CFU/mL approximately, but never completely sterilize. The plasma discharge with our characteristics could be used for the sterilization of the aforementioned superficially growing microbes, but does not sufficiently affect deeper layers and thus seems to be a limitation for eradication of the already erupted colonies. PMID:24464536

Justan, I; Cernohorska, L; Dvorak, Z; Slavicek, P

2014-07-01

347

Laser-Induced Fluorescence Image of OH Radicals for Atmospheric-Pressure Nonequilibrium Dry Air Gas DC Pulse Plasma Jet  

Microsoft Academic Search

OH radicals were successfully measured for the first time ever in an atmospheric-pressure nonequilibrium DC pulse discharge plasma jet in dry air gas using the laser-induced fluorescence method and OH transition [A2Sigma+(v'=1)larrX2Pi(v\\

Toshifumi Yuji; H. Kawano; S. Kanazawa; T. Ohkubo; H. Akatsuka

2008-01-01

348

Stereolithography based method of creating custom gas density profile targets for high intensity laser-plasma experiments  

NASA Astrophysics Data System (ADS)

Laser based stereolithography methods are shown to be useful for production of gas targets for high intensity laser-plasma interaction experiments. A cylindrically symmetric nozzle with an opening of approximately 100 ?m and a periodic attachment of variable periodicity are outlined in detail with associated density profile characterization. Both components are durable within the limits of relevant experiments.

Jolly, S. W.; He, Z.; McGuffey, C.; Schumaker, W.; Krushelnick, K.; Thomas, A. G. R.

2012-07-01

349

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

Microsoft Academic Search

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

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

2008-01-01

350

Constraining sterile neutrino warm dark matter with Chandra observations of the Andromeda galaxy  

SciTech Connect

We use the Chandra unresolved X-ray emission spectrum from a 12'–28' (2.8–6.4 kpc) annular region of the Andromeda galaxy to constrain the radiative decay of sterile neutrino warm dark matter. By excising the most baryon-dominated, central 2.8 kpc of the galaxy, we reduce the uncertainties in our estimate of the dark matter mass within the field of view and improve the signal-to-noise ratio of prospective sterile neutrino decay signatures relative to hot gas and unresolved stellar emission. Our findings impose the most stringent limit on the sterile neutrino mass to date in the context of the Dodelson-Widrow model, m{sub s} < 2.2 keV (95% C.L.). Our results also constrain alternative sterile neutrino production scenarios at very small active-sterile neutrino mixing angles.

Watson, Casey R.; Polley, Nicholas K. [Department of Physics and Astronomy, Millikin University, Decatur, Illinois 62522 (United States); Li, Zhiyuan, E-mail: crwatson@millikin.edu, E-mail: zyli@astro.ucla.edu, E-mail: npolley@millikin.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2012-03-01

351

[Compatibilities and incompatibilities between gamma rays and ethylene oxide as consecutive sterilization methods].  

PubMed

The doubt regarding the re-sterilization of articles made of polyvinyl chloride (PVC) sterilized with gamma radiation (GR) and subsequently with ethylene oxide (EO) persists to date. Through a systematic literature review, this article analyzed studies that demonstrated compatibilities and incompatibilities between the sterilization processes with GR and EO, when used as consecutive sterilization methods. Seven studies were analyzed. It was verified that there is a multifactor influence regarding the safety of the procedure and that the chromatography analytical method employed by most studies yielded controversial results. This fact indicates the need for further studies on the issue, using more sensitive analytical methods than gas chromatography, such as the biological reactivity test in cell cultures, in an attempt to clarify the chronic doubt regarding the adequacy or inadequacy of sterilizing previously gamma-irradiated materials with EtO. PMID:21337800

de Souza, Rafael Queiroz; Graziano, Kazuko Uchikawa

2010-12-01

352

Anomalous kinetic energy of a system of dust particles in a gas discharge plasma  

SciTech Connect

The system of equations of motion of dust particles in a near-electrode layer of a gas discharge has been formulated taking into account fluctuations of the charge of a dust particle and the features of the nearelectrode layer of the discharge. The molecular dynamics simulation of the system of dust particles has been carried out. Performing a theoretical analysis of the simulation results, a mechanism of increasing the average kinetic energy of dust particles in the gas discharge plasma has been proposed. According to this mechanism, the heating of the vertical oscillations of dust particles is initiated by induced oscillations generated by fluctuations of the charge of dust particles, and the energy transfer from vertical to horizontal oscillations can be based on the parametric resonance phenomenon. The combination of the parametric and induced resonances makes it possible to explain an anomalously high kinetic energy of dust particles. The estimate of the frequency, amplitude, and kinetic energy of dust particles are close to the respective experimental values.

Norman, G. E., E-mail: norman@ihed.ras.ru; Stegailov, V. V., E-mail: stegailov@gmail.com; Timofeev, A. V., E-mail: timofeevalvl@gmail.com [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2011-11-15

353

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

NASA Astrophysics Data System (ADS)

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

Ferland, Gary

2014-10-01

354

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

PubMed Central

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

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

2014-01-01

355

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

356

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

PubMed

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

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

2014-01-01

357

Steam Sterilization Cycles for Lab Applications  

E-print Network

STERILIZER FACILITY CEILING SIDE VIEW OF BASIC COMPONENTS FACILITY CEILING FACILITY WALL PARTITION SECONDARY and controlled by a temperature sensor in the drain line) for a set time.( y p ) Objective: To sterilize

Farritor, Shane

358

Sterilization of Persons with Mental Retardation.  

ERIC Educational Resources Information Center

This article examines the historical, legal, and ethical concerns regarding sterilization for persons with mental retardation and offers guidelines to help counsel individuals with disabilities or their families regarding decision making about sterilization. (DB)

Elkins, Thomas E.; Andersen, H. Frank

1992-01-01

359

Plasma metabolomic profiling of dairy cows affected with ketosis using gas chromatography/mass spectrometry  

PubMed Central

Background Ketosis is an important problem for dairy cows` production performance. However, it is still little known about plasma metabolomics details of dairy ketosis. Results A gas chromatography/mass spectrometry (GC/MS) technique was used to investigate plasma metabolic differences in cows that had clinical ketosis (CK, n=22), subclinical ketosis (SK, n=32), or were clinically normal controls (NC, n=22). The endogenous plasma metabolome was measured by chemical derivatization followed by GC/MS, which led to the detection of 267 variables. A two-sample t-test of 30, 32, and 13 metabolites showed statistically significant differences between SK and NC, CK and NC, and CK and SK, respectively. Orthogonal signal correction-partial least-square discriminant analysis (OPLS-DA) revealed that the metabolic patterns of both CK and SK were mostly similar, with the exception of a few differences. The development of CK and SK involved disturbances in many metabolic pathways, mainly including fatty acid metabolism, amino acid metabolism, glycolysis, gluconeogenesis, and the pentose phosphate pathway. A diagnostic model arbitrary two groups was constructed using OPLS-DA and receiver–operator characteristic curves (ROC). Multivariate statistical diagnostics yielded the 19 potential biomarkers for SK and NC, 31 for CK and NC, and 8 for CK and SK with area under the curve (AUC) values. Our results showed the potential biomarkers from CK, SK, and NC, including carbohydrates, fatty acids, amino acids, even sitosterol and vitamin E isomers, etc. 2-piperidinecarboxylic acid and cis-9-hexadecenoic acid were closely associated with metabolic perturbations in ketosis as Glc, BHBA and NEFA for dealing with metabolic disturbances of ketosis in clinical practice. However, further research is needed to explain changes of 2,3,4-trihydroxybutyric acid, 3,4-dihydroxybutyric acid, ?-aminobutyric acid, methylmalonic acid, sitosterol and ?-tocopherol in CK and SK, and to reveal differences between CK and SK. Conclusion Our study shows that some new biomarkers of ketosis from plasma may find new metabolic changes to have clinically new utility and significance in diagnosis, prognosis, and prevention of ketosis in the future. PMID:24070026

2013-01-01

360

The impact of plasma-wall interaction on the gas mixing efficiency in electron cyclotron resonance ion sourcea)  

NASA Astrophysics Data System (ADS)

It is generally accepted that different effects are necessary to explain the gas mixing method of increasing the output of highly charged ions from an ECRIS. The two most important effects are the mass effect and the dilution effect. Their relative weights have not been determined experimentally yet, but it is generally assumed that the mass effect is dominant in standard ECRIS installations with stainless steel plasma chambers. In order to gain more insight into the physics of the gas mixing effect and in particular on the relevance of the dilution process, we have carried out a study where we have investigated the role of the plasma-wall interaction on the gas mixing effect. In this contribution, we shall discuss Charge state distributions spectra, measured at the Frankfurt ECRIS using different working gases, pure argon, a mixture of argon and oxygen, and argon mixed with neon.

Schachter, L.; Stiebing, K. E.; Dobrescu, S.

2012-02-01

361

The impact of plasma-wall interaction on the gas mixing efficiency in electron cyclotron resonance ion source  

SciTech Connect

It is generally accepted that different effects are necessary to explain the gas mixing method of increasing the output of highly charged ions from an ECRIS. The two most important effects are the mass effect and the dilution effect. Their relative weights have not been determined experimentally yet, but it is generally assumed that the mass effect is dominant in standard ECRIS installations with stainless steel plasma chambers. In order to gain more insight into the physics of the gas mixing effect and in particular on the relevance of the dilution process, we have carried out a study where we have investigated the role of the plasma-wall interaction on the gas mixing effect. In this contribution, we shall discuss Charge state distributions spectra, measured at the Frankfurt ECRIS using different working gases, pure argon, a mixture of argon and oxygen, and argon mixed with neon.

Schachter, L.; Dobrescu, S. [National Institute for Physics and Nuclear Engineering, Bucharest (Romania); Stiebing, K. E. [Institut fuer Kernphysik der J. W. Goethe-Universitaet, Frankfurt/Main (Germany)

2012-02-15

362

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

PubMed Central

Indium phosphide nanocrystals (InP NCs) with diameters ranging from 2 to 5 nm were synthesized with a scalable, flow-through, nonthermal plasma process at a rate ranging from 10 to 40 mg/h. The NC size is controlled through the plasma operating parameters, with the residence time of the gas in the plasma region strongly influencing the NC size. The NC size distribution is narrow with the standard deviation being less than 20% of the mean NC size. Zinc sulfide (ZnS) shells were grown around the plasma-synthesized InP NCs in a liquid phase reaction. Photoluminescence with quantum yields as high as 15% were observed for the InP/ZnS core-shell NCs. PMID:21711589

2011-01-01

363

Transgenic technologies to induce sterility  

PubMed Central

The last few years have witnessed a considerable expansion in the number of tools available to perform molecular and genetic studies on the genome of Anopheles mosquitoes, the vectors of human malaria. As a consequence, knowledge of aspects of the biology of mosquitoes, such as immunity, reproduction and behaviour, that are relevant to their ability to transmit disease is rapidly increasing, and could be translated into concrete benefits for malaria control strategies. Amongst the most important scientific advances, the development of transgenic technologies for Anopheles mosquitoes provides a crucial opportunity to improve current vector control measures or design novel ones. In particular, the use of genetic modification of the mosquito genome could provide for a more effective deployment of the sterile insect technique (SIT) against vector populations in the field. Currently, SIT relies on the release of radiation sterilized males, which compete with wild males for mating with wild females. The induction of sterility in males through the genetic manipulation of the mosquito genome, already achieved in a number of other insect species, could eliminate the need for radiation and increase the efficiency of SIT-based strategies. This paper provides an overview of the mechanisms already in use for inducing sterility by transgenesis in Drosophila and other insects, and speculates on possible ways to apply similar approaches to Anopheles mosquitoes. PMID:19917077

Catteruccia, Flaminia; Crisanti, Andrea; Wimmer, Ernst A

2009-01-01

364

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

365

Genetic Basis of the Sterile Insect Technique  

Microsoft Academic Search

The use of the sterile insect technique (SIT) for insect control relies on the introduction of sterility in the females of the wild population. This sterility is produced following the mating of these females with released males carrying, in their sperm, dominant lethal mutations that have been induced by ionizing radiation. The reasons why the SIT can only be effective

A. S. ROBINSON

366

Sterile Plus Active Neutrinos and Neutrino Oscillations  

NASA Astrophysics Data System (ADS)

Using a 3 + 1 neutrino model with one sterile and the three standard active neutrinos with a 4 × 4 unitary transformation matrix, U, relating flavor to mass neutrino states, the probability of ? ? to ? e transition is estimated using sterile-active neutrino masses determined by MiniBooNE and other experiments and sterile-active neutrino angles in the 4 × 4 U matrix.

Kisslinger, Leonard S.

2014-09-01

367

Birth planning and sterilization in China  

Microsoft Academic Search

Sterilization is the most prevalent method of contraception in China. Approximately half of all women of reproductive age report that they or their husbands are sterilized. Using data from the China Health and Nutrition Survey we describe patterns of sterilization in eight Chinese provinces. With a discrete-time event history model we investigate the link between characteristics of local birth planning

SUSAN E. SHORT; MA LINMAO; YU WENTAO

2000-01-01

368

Limitations of extended gas delivery tubes used for fuelling mitigated plasma disruptions, and a unique injection concept for prompt gas delivery  

NASA Astrophysics Data System (ADS)

Modelling high-pressure gas flows through long extended delivery tubes used for massive particle fuelling of tokamaks during a major disruptive instability or a preemptive fast plasma shutdown is presented using analytical theory and simulation. For steady-state flows, expressions were derived and compared with experiments for the transition diameter and inlet Mach number of a straight tube (pipe) attached to a 'nozzle-like' inlet valve, such that increases in pipe diameter have no effect on the flow rate (valve-limited flow), and decreases below the transition diameter cause decreasing flow rates (friction-limited flow). Analytical expressions for the exit outflow rate and other gas dynamic variables during the initial unsteady gas flow buildup were developed from the classical 1D centred expansion wave problem and compared with 2D axisymmetric FLUENT simulations with wall friction, and good agreement was found for sufficiently high-conductance pipes. The intrinsic time delay before steady-state outflow is reached can seriously limit plasma density increases during the disruption, as the disruption time scale is similar to the delay time or 'rise time' of the outflow at the exit plane. Thus, conditions required for strong collisional dissipation of destructive runaway electron currents can be compromised. A unique gas injection scheme 'burst membrane gas injection' is also presented in which a steady-state outflow at the exit plane can be established promptly once the membrane bursts. It is shown that the theoretically ideal rise time of the gas at the exit plane will be zero if the membrane had an instantaneous opening time, therefore the true rise time will be limited only by the rupture time of a real bursting disc. The duration of the initial steady-state gas delivery phase can be matched to the relevant disruption time scales (or runaway formation time) by simply adjusting the tube length.

Parks, P. B.; Wu, W.

2011-07-01

369

Experiment on the plasma-loaded backward-wave oscillator using a gas-loaded foil-less diode  

NASA Astrophysics Data System (ADS)

High-power microwave radiation of 9.5-13.4 GHz was generated in a plasma-loaded backward-wave oscillator employing a relativistic electron beam of 400-500 keV and 1-3 kA. This experiment was to re-examine and confirm the previous works that had been done in other various institutions. The relativistic electron beam, which was produced from a helium gas-loaded foil-less diode, was injected into the helium gas-loaded rippled-wall waveguide of the backward-wave oscillator, generating a plasma in the waveguide and then the high-power microwave radiation. A sharp increase in the output microwave power has been observed in a narrow range of the helium gas pressure, and two dips in the microwave emission have also been found in a certain range of the axial magnetic field. Additionally, at certain values of the helium gas pressure and guide magnetic field, the total microwave emission of the plasma-loaded backward-wave oscillator was found to be seven times as large as that of the vacuum case. The highest interaction efficiency was estimated to be about 29% for the present experiment.

Qian, Bao-Liang; Li, Chuan-Lu; Liu, Yong-Gui; Zhang, Jian-De; Tan, Qi-Mei; Liu, Jin-Liang; Liu, Cun-Hua; Chen, Dong-Qun; Li, Xiang-Sheng; Liu, Che-Bo

2000-09-01

370

Formation of a Boundary-Free Dust Cluster in a Low-Pressure Gas-Discharge Plasma  

SciTech Connect

An attraction between negatively charged micron-sized plastic particles was observed in the bulk of a low-pressure gas-discharge plasma under microgravity conditions. This attraction had led to the formation of a boundary-free dust cluster, containing one big central particle with a radius of about 6 {mu}m and about 30 1 {mu}m-sized particles situated on a sphere with a radius of 190 {mu}m and with the big particle in the center. The stability of this boundary-free dust cluster was possible due to its confinement by the plasma flux on the central dust particle.

Usachev, A. D.; Zobnin, A. V.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures of Russian Academy of Sciences, Moscow, 125412 (Russian Federation); Annaratone, B. M. [CNRS/Universite de Provence, Centre de St. Jerome case 321, 13397, Marseille (France); Thoma, M. H.; Hoefner, H.; Kretschmer, M.; Fink, M.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, P.O. Box 1321, D- 85741 Garching (Germany)

2009-01-30

371

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

372

Ion angular distribution in plasma of vacuum arc ion source with composite cathode and elevated gas pressure.  

PubMed

The Metal Vapor Vacuum Arc (MEVVA) ion sources are capable of generating ion beams of almost all metals of the periodic table. For this kind of ion source, a combination of gas feeding with magnetic field allows the simultaneous generation of both metal and gaseous ions. That makes the MEVVA ion source an excellent instrument for science and application. This work presents results of investigation for ion angular distributions in vacuum arc plasma of Mevva-V.Ru ion source for composite cathodes and for elevated gas pressure. It was shown that for all the cathode materials, singly charged ions have wider angular distribution than multiply charged ions. Increasing the working gas pressure leads to a significant change in the angular distribution of gaseous ions, while with the distribution of metal ions gas remains practically unchanged. The reasons for such different influences are discussed. PMID:24593598

Nikolaev, A G; Savkin, K P; Yushkov, G Yu; Oks, E M

2014-02-01

373

Ion angular distribution in plasma of vacuum arc ion source with composite cathode and elevated gas pressure  

NASA Astrophysics Data System (ADS)

The Metal Vapor Vacuum Arc (MEVVA) ion sources are capable of generating ion beams of almost all metals of the periodic table. For this kind of ion source, a combination of gas feeding with magnetic field allows the simultaneous generation of both metal and gaseous ions. That makes the MEVVA ion source an excellent instrument for science and application. This work presents results of investigation for ion angular distributions in vacuum arc plasma of Mevva-V.Ru ion source for composite cathodes and for elevated gas pressure. It was shown that for all the cathode materials, singly charged ions have wider angular distribution than multiply charged ions. Increasing the working gas pressure leads to a significant change in the angular distribution of gaseous ions, while with the distribution of metal ions gas remains practically unchanged. The reasons for such different influences are discussed.

Nikolaev, A. G.; Savkin, K. P.; Yushkov, G. Yu.; Oks, E. M.

2014-02-01

374

A differentially pumped argon plasma in the linear plasma generator Magnum-PSI: gas flow and dynamics of the ionized fraction  

NASA Astrophysics Data System (ADS)

Magnum-PSI is a linear plasma generator designed to reach the plasma-surface interaction (PSI) regime of ITER and nuclear fusion reactors beyond ITER. To reach this regime, the influx of cold neutrals from the source must be significantly lower than the plasma flux reaching the target. This is achieved by a differential pumping scheme, where the vacuum vessel is divided by skimmers into separate chambers which are individually pumped. The non-magnetized expansion of 5 Pa m3 s-1 (3 slm) argon in a low background pressure was studied in the differentially pumped vacuum vessel fitted with non-cooled flat skimmers. The behavior of the neutral component was studied with direct simulation Monte Carlo simulations and Rayleigh scattering measurements. Thomson scattering and double Langmuir probe measurements were performed on the ionized fraction. It was found that the electrons and neutral particles are not completely coupled in the shock front. The neutral fraction shows clear signs of invasion from hotter background gas, causing the average temperature and density to increase before the shock. This is also shown in the ionization ratio, which has been determined in front of and behind the first skimmer. This study helps us to understand the behavior of the gas flow in the machine and validates our modeling.

van Eck, H. J. N.; Hansen, T. A. R.; Kleyn, A. W.; van der Meiden, H. J.; Schram, D. C.; Zeijlmans van Emmichoven, P. A.

2011-08-01

375

Plasma steam reforming of E85 for hydrogen rich gas production  

NASA Astrophysics Data System (ADS)

E85 (85 vol% ethanol and 15 vol% gasoline) is a partly renewable fuel that is increasing in supply availability. Hydrogen production from E85 for fuel cell or internal combustion engine applications is a potential method for reducing CO2 emissions. Steam reforming of E85 using a nonthermal plasma (pulse corona discharge) reactor has been exploited at low temperature (200-300 °C) without external heating, diluent gas, oxidant or catalyst in this work. Several operational parameters, including the discharge current, E85 concentration and feed flow rate, have been investigated. The results show that hydrogen rich gases (63-67% H2 and 22-29% CO, with small amounts of CO2, C2 hydrocarbons and CH4) can be produced by this method. A comparison with ethanol reforming and gasoline reforming under identical conditions has also been made and the behaviour of E85 reforming is found to be close to that of ethanol reforming with slightly higher C2 hydrocarbons yields.

Zhu, Xinli; Hoang, Trung; Lobban, Lance L.; Mallinson, Richard G.

2011-07-01

376

Influence of dust-particle concentration on gas-discharge plasma.  

PubMed

A self-consistent kinetic model of a low-pressure dc glow discharge with dust particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the dust-particle surface and on the discharge tube wall were taken into account. The influence of dust-particle concentration N(d) on gas discharge and dust particles parameters was investigated. It is shown that the increase of N(d) leads to the increase of an averaged electric field and ion density, and to the decrease of a dust-particle charge and electron density in the dusty cloud. The results were obtained in a wide region of different discharge and dusty plasma parameters: dust particles density 10(2)-10(8) cm(-3), discharge current density 10(-1)-10(1) mA/cm(2), and dust particles radius 1, 2, and 5 microm. The scaling laws for dust-particle surface potential and electric filed dependencies on dust-particle density, particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the dust particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of dust particles and discharge parameters. PMID:20365480

Sukhinin, G I; Fedoseev, A V

2010-01-01

377

Production of hydrogen-rich gas from methane by thermal plasma reform.  

PubMed

This study investigated the reforming characteristics and optimum operating condition of the high-temperature plasma torch (so called plasmatron) for hydrogen-rich gas (syngas) production. At the optimum condition, the composition of produced syngas was 45.4% hydrogen (H2), 6.9% carbon monoxide (CO), 1.5% carbon dioxide (CO2), and 1.1% acetylene (C2H2). The H2/CO ratio was 6.6, hydrogen yield was 78.8%, and the energy conversion rate was 63.6%. To obtain the optimum operating condition, parametric studies were carried out examining the effects of O2/CH4 ratio, steam/CH4 ratio, and Ni catalyst addition in reactor. When the steam/CH4 ratio was 1.23, the production of hydrogen was maximized and the methane conversion rate was 99.7%. The syngas composition was determined to be 50.4% H2, 5.7% CO, 13.8% CO2, and 1.1% C2H2. The H2/CO ratio was 9.7, hydrogen yield was 93.7%, and the energy conversion rate was 78.8%. Hydrogen production with catalyst was effective, compared with no catalyst. PMID:18200929

Chun, Young N; Kim, Seong C

2007-12-01

378

Control of nanoparticle synthesis using physical and chemical dynamics of gas-liquid interfacial non-equilibrium plasmas  

NASA Astrophysics Data System (ADS)

Plasmas generated in contact with liquids have attracted considerable attention as a novel reactive field in nano-biomaterial creation because the brand-new chemical and biological reactions are yielded at the gas-liquid interface, which are induced by the physical actions of the non-equilibrium plasmas. Highly ordered periodic structures of gold nanoparticles (AuNPs) are formed by transcribing the plasma structure to the surface of the liquid, where the spatially selective synthesis of the AuNPs is realized. Furthermore, the plasma structure is controlled using a ring or disk electrode under strong magnetic fields up to 4 T. The ring structure of the nanoparticles is found to be formed in accordance with the shadow region of the ring electrode. It is found that the AuNPs are synthesized by the reduction effect of the hydrogen radical via irradiation of neutral radicals of the plasma and are destroyed by the oxidation effect of the fluorine radical via high-energy plasma-ion irradiation.

Kaneko, T.; Takahashi, S.; Hatakeyama, R.

2012-12-01

379

Studies of xenon ECR plasma: search for a better understanding of the gas-mixing and anomalous effects  

NASA Astrophysics Data System (ADS)

Pure and oxygen-mixed xenon plasmas were produced using 10 GHz all-permanent-magnet electron cyclotron resonance (ECR) ion source. The charge state distributions (CSDs) of highly abundant isotopes (129Xe, 131 Xe and 132 Xe) were studied by extracting the ions from the plasma and analyzed them in mass and energy using a large acceptance analyzer-switching dipole magnet. In earlier studies (Drentje 1992 Rev. Sci. Instrum. 63 2875, Kawai et al 2001 Plasma Sources Sci. Technol. 10 451), the CSD of oxygen and nitrogen ECR plasmas showed that isotopic intensity ratio of ions varies with the charge state (anomalous effect). The anomalous effect in the pure and oxygen-mixed xenon ECR plasma was absent up to +13 charge state. With oxygen, a very small positive gas-mixing effect on the charge state beyond +8 was observed. In this paper, we present CSDs of xenon isotopes with and without oxygen mixing (at optimized ion source parameters) and compare the intensity of isotopes for various charge states to shed light on the previously noticed anomalous effect in the ECR plasma.

Kumar, P.; Mal, Kedar; Kanjilal, D.

2014-12-01

380

Microwave sterilization in school microbiology  

Microsoft Academic Search

For a long time the standard procedure for ensuring total sterilization of equipment and culture media for microbiological investigations has been to autoclave; this method destroys even the most resistant bacterial spores by a combination of heat and pressure, using steam (typically 120°C and 100 kPA for 15–20 minutes). Most biology teachers are familiar with the noise, smell, condensation, and

Brian Wynn; Angela Dixon

1988-01-01

381

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

382

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

383

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

384

Measurement of Pyrethroid, Organophosphorus, and Carbamate Insecticides in Human Plasma using Isotope Dilution Gas Chromatography-High Resolution Mass Spectrometry  

PubMed Central

We have developed a gas chromatography-high resolution mass spectrometry method for measuring pyrethroid, organophosphorus, carbamate and fipronil pesticides and the synergist piperonyl butoxide in human plasma. Plasma samples were extracted using solid phase extraction and were then concentrated for injection and analysis using isotope dilution gas chromatography-high resolution mass spectrometry. The limits of detection ranged from 10 to 158 pg/mL with relative recoveries at concentrations near the LODs (e.g., 25 or 250 pg/mL) ranging from 87% to 156% (9 of the 16 compounds were withing ± 15% of 100%). The extraction recoveries ranged from 20% to 98% and the overall method relative standard deviations were typically less than 20% with some exceptions. Analytical characteristics were determined at 25, 250, and 1000 pg/mL. PMID:20434413

Pérez, José J.; Williams, Megan K.; Weerasekera, Gayanga; Smith, Kimberly; Whyatt, Robin M.; Needham, Larry L.; Barr, Dana Boyd

2010-01-01

385

Investigation of 50 Hz Pulsed DC Nitrogen Plasma with Active Screen Cage by Trace Rare Gas Optical Emission Spectroscopy  

NASA Astrophysics Data System (ADS)

Optical emission spectroscopy is used to investigate the nitrogen-hydrogen with trace rare gas (4% Ar) plasma generated by 50 Hz pulsed DC discharges. The filling pressure varies from 1 mbar to 5 mbar and the current density ranges from 1 mA·cm-2 to 4 mA·cm-2. The hydrogen concentration in the mixture plasma varies from 0% to 80%, with the objective of identifying the optimum pressure, current density and hydrogen concentration for active species ([N] and [N2]) generation. It is observed that in an N2-H2 gas mixture, the concentration of N atom density decreases with filling pressure and increases with current density, with other parameters of the discharge kept unchanged. The maximum concentrations of active species were found for 40% H2 in the mixture at 3 mbar pressure and current density of 4 mA·cm-2.

Saeed, A.; W. Khan, A.; Shafiq, M.; F., Jan; Abrar, M.; Zaka-Ul-Islam, M.; Zakaullah, M.

2014-04-01

386

Generation and characterization of plasma channels in gas puff targets using soft X-ray radiography technique  

SciTech Connect

We present our recent results of a formation and characterization of plasma channels in elongated krypton and xenon gas puff targets. The study of their formation and temporal expansion was carried out using a combination of a soft X-ray radiography (shadowgraphy) and pinhole camera imaging. Two high-energy short laser pulses were used to produce the channels. When a pumping laser pulse was shaped into a line focus, using cylindrical and spherical lenses, the channels were not produced because much smaller energy density was deposited in the gas puff target. However, when a point focus was obtained, using just a spherical lens, the plasma channels appeared. The channels were up to 9?mm in length, had a quite uniform density profile, and expanded in time with velocities of about 2?cm/?s.

Wachulak, P. W., E-mail: wachulak@gmail.com; Bartnik, A.; Jarocki, R.; Fok, T.; W?grzy?ski, ?.; Kostecki, J.; Szczurek, M.; Jabczy?ski, J.; Fiedorowicz, H. [Institute of Optoelectronics, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw (Poland)

2014-10-15

387

On time resolved gas temperature measurements in a pulsed dc plasma using quantum cascade laser absorption spectroscopy  

NASA Astrophysics Data System (ADS)

With a time resolution of 33 µs, the gas temperature in a pulsed dc air plasma admixed with 0.8% NO has been measured by quantum cascade laser absorption spectroscopy (QCLAS). For this purpose, the temperature dependent intensity ratios of two absorption structures of NO at 1900 cm-1 (5.26 µm) have been used. The QCLAS system worked in the Intra Pulse Mode with a pulse repetition frequency of 30 kHz leading to a spectrum recorded each 33 µs. In a low pressure discharge, the influence of nonlinear absorption phenomena causing strong distorted absorption structures of NO has been taken into account by a calibration routine based on tabulated line strengths. Different mean plasma currents have been applied to the discharge leading to gas temperature values ranging from about 300 K up to about 500 K.

Hübner, M.; Marinov, D.; Guaitella, O.; Rousseau, A.; Röpcke, J.

2012-11-01

388

Generation and characterization of plasma channels in gas puff targets using soft X-ray radiography technique  

NASA Astrophysics Data System (ADS)

We present our recent results of a formation and characterization of plasma channels in elongated krypton and xenon gas puff targets. The study of their formation and temporal expansion was carried out using a combination of a soft X-ray radiography (shadowgraphy) and pinhole camera imaging. Two high-energy short laser pulses were used to produce the channels. When a pumping laser pulse was shaped into a line focus, using cylindrical and spherical lenses, the channels were not produced because much smaller energy density was deposited in the gas puff target. However, when a point focus was obtained, using just a spherical lens, the plasma channels appeared. The channels were up to 9 mm in length, had a quite uniform density profile, and expanded in time with velocities of about 2 cm/?s.

Wachulak, P. W.; Bartnik, A.; Jarocki, R.; Fok, T.; Wegrzy?ski, ?.; Kostecki, J.; Szczurek, M.; Jabczy?ski, J.; Fiedorowicz, H.

2014-10-01

389

The discharge mode transition and O(5p1) production mechanism of pulsed radio frequency capacitively coupled plasma  

NASA Astrophysics Data System (ADS)

The discharge mode transition from uniform plasma across the gas gap to the ? mode happens at the rising phase of the pulsed radio frequency capacitively coupled plasma (PRF CCP). This transition is attributed to the fast increasing stochastic heating at the edge of sheath. In the second stage with the stable current and voltage amplitude, the consistency between experimental and numerical spatial-temporal 777 nm emission profile suggests that He* and He2* dominate the production of O(5p1) through dissociation and excitation of O2. Finally, the sterilization efficiency of PRF CCP is found to be higher than that of plasma jet.

Liu, X. Y.; Hu, J. T.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Shi, J. J.

2012-07-01

390

Effect of sterilization on non-woven polyethylene terephthalate fiber structures for vascular grafts.  

PubMed

Non-woven polyethylene terephthalate (PET) fibers produced via melt blowing and compounded into a 6 mm diameter 3D tubular scaffold were developed with artery matching mechanical properties. This work compares the effects of ethylene oxide (EtO) and low temperature plasma (LTP) sterilization on PET surface chemistry and biocompatibility. As seen through X-ray photoelectron spectroscopy (XPS) analysis, LTP sterilization led to an increase in overall oxygen content and the creation of new hydroxyl groups. EtO sterilization induced alkylation of the PET polymer. The in vitro cytotoxicity showed similar fibroblastic viability on LTP- and EtO-treated PET fibers. However, TNF-? release levels, indicative of macrophage activation, were significantly higher when macrophages were incubated on EtO-treated PET fibers. Subcutaneous mice implantation revealed an inflammatory response with foreign body reaction to PET grafts independent of the sterilization procedure. PMID:21038349

Dimitrievska, Sashka; Petit, Alain; Doillon, Charles J; Epure, Laura; Ajji, Abdellah; Yahia, L'Hocine; Bureau, Martin N

2011-01-10

391

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

PubMed

Shape-memory polymers (SMPs) are being increasingly proposed for use in biomedical devices. This paper investigates the cytotoxicity, surface characteristics and thermomechanics of two acrylate-based SMP networks as a function of sterilization using a minimal essential media elution test, FTIR-ATR and dynamic mechanical analysis (DMA). Networks sterilized by low-temperature plasma elicited a cytotoxic response and are shown to completely destroy the cell monolayer. FTIR-ATR analysis showed evidence of surface oxidation with an increase and broadening of the absorbance peak from approximately 3500 to 3100 cm(-1), which is associated with an increase in hydroxyl groups. DMA revealed small, but statistically significant, differences in reduction of the glass transition temperatures of both networks when sterilized with gamma irradiation. One network showed an increase in rubbery modulus, which is an indication of crosslink density, after gamma irradiation. Lastly, practical sterilization concerns of SMP devices are discussed in light of the different methods. PMID:18458497

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

2008-03-01

392

Gas- and plasma-driven hydrogen permeation through a reduced activation ferritic steel alloy F82H  

NASA Astrophysics Data System (ADS)

The first wall of a magnetic fusion power reactor will be subjected to hydrogen isotope permeation by the two mechanisms: one is gas-driven and the other is plasma-driven. Hydrogen transport through a reduced activation ferritic steel alloy F82H has been investigated using a steady-state laboratory-scale plasma device. Permeation parameters including permeability, solubility and diffusivity have been measured in the temperature range from 150 to 520 °C. The surface recombination coefficient for hydrogen has also been estimated by a one-dimensional steady-state permeation model with the input data taken from experiments. Using these parameters, the hydrogen plasma-driven permeation flux and inventory for a 0.5 cm thick first wall around 500 °C are estimated to be ?1.0 × 1013 atom cm-2 s-1 and ?2 × 1016 atom cm-3, respectively. Also, the implications of all these data on reactor operation are discussed.

Zhou, Haishan; Hirooka, Yoshi; Ashikawa, Naoko; Muroga, Takeo; Sagara, Akio

2014-12-01

393

Optimization of a gas discharge plasma source for extreme ultraviolet interference lithography at a wavelength of 11 nm  

Microsoft Academic Search

In this work, we report about the optimization of the spectral emission characteristic of a gas discharge plasma source for high-resolution extreme ultraviolet (EUV) interference lithography based on achromatic Talbot self-imaging. The working parameters of the source are optimized to achieve a required narrowband emission spectrum and to fulfill the necessary coherence and intensity requirements. The intense 4f-4d transitions around

K. Bergmann; S. V. Danylyuk; L. Juschkin

2009-01-01

394

Experimental Evaluation of SI Engine Operation Supplemented by Hydrogen Rich Gas from a Compact Plasma Boosted Reformer  

Microsoft Academic Search

It is well known that hydrogen addition to spark-ignited (SI) engines can reduce exhaust emissions and increase efficiency. Micro plasmatron fuel converters can be used for onboard generation of hydrogen-rich gas by partial oxidation of a wide range of fuels. These plasma-boosted microreformers are compact, rugged, and provide rapid response. With hydrogen supplement to the main fuel, SI engines can

Jr. J. B. Green; N. Domingo; J. M. E. Storey; R. M. Wagner; J. S. Armfield; L. Bromberg; D. R. Cohn; A. Rabinovich; N. Alexeev

2000-01-01

395

First In-Situ Plasma and Neutral Gas Measurements at Comet Halley  

Microsoft Academic Search

The first in situ observations and a description of the large-scale behavior of comet Halley's plasma environment are presented. The changes of the plasma parameters and distributions as a function of distance from Halley's nucleus, the existence and structure of the cometary bow shock, the change in chemical composition of the heavily mass-loaded plasma as the comet is approached, and

K. I. Gringauz; T. I. Gombosi; A. P. Remisov; I. Apathy; T. Szemerey; M. I. Verigin; L. I. Denshchikova; A. V. Dyachkov; E. Keppler; I. N. Klimenko; A. K. Richter; A. J. Somogyi; K. Szego; S. Szendro; M. Tatrallyay; A. Varga; G. A. Vladimirova

1986-01-01

396

Gas temperature effect on the time for onset of particle nucleation in argon diluted acetylene plasma  

E-print Network

, Serbia and Montenegro 1. Introduction Particle nucleation in processing plasmas is an important issue to understand the basic problems of the involved plasma chemistry. On the other hand it is interesting plasma I. Stefanovi1, 2 , E. Kovacevi1 , J. Berndt1 , and J. Winter1 1 Institute for Experimental Physics

Paris-Sud XI, Université de

397

Stability of plasma gamma-hydroxybutyrate determined by gas chromatography-positive ion chemical ionization-mass spectrometry.  

PubMed

An effective method for the determination of gamma-hydroxybutyric acid (GHB) in human plasma is described that utilizes a simple liquid-liquid extraction procedure and gas chromatography-positive ion chemical ionization-mass spectrometry (GC-PCI-MS). The method has been used to study the stability of plasma GHB under several storage conditions. Following the extraction with acetonitrile, GHB and deuterated GHB (GHB-d(6)) were derivatized with N,O-bis[trimethylsilyl] trifluoroacetamide (BSFTA). After the separation on a capillary GC column, the derivatives were ionized with ammonia reagent gas and analyzed by MS. The lower limit of quantitation in 100 microL of plasma was 2.5 microg/mL, over a range from 2.5 to 250 microg/mL. The coefficients of variation did not exceed 3.9% and the mean measured concentrations did not deviate more than 8% from the target for both intra- and interassay precision and accuracy. Plasma GHB was found to be stable at -20 degrees C for up to 9 months, at room temperature for 48 h, and after 3 freeze/thaw cycles. It was also found to be stable in processed samples stored at room temperature for 5 days and for 15 days at -20 degrees C. PMID:14606997

Chen, Meng; Andrenyak, David M; Moody, David E; Foltz, Rodger L

2003-10-01

398

Gas ratio effects on the Si etch rate and profile uniformity in an inductively coupled Ar/CF4 plasma  

NASA Astrophysics Data System (ADS)

In this work, a hybrid model is used to investigate the effect of different gas ratios on the Si etching and polymer film deposition characteristics in an Ar/CF4 inductively coupled plasma. The influence of the surface processes on the bulk plasma properties is studied, and also the spatial characteristics of important gas phase and etched species. The densities of F and CF2 decrease when the surface module is included in the simulations, due to the species consumption caused by etching and polymer deposition. The influence of the surface processes on the bulk plasma depends on the Ar/CF4 gas ratio. The deposited polymer becomes thicker at high CF4 content because of more abundant CFx radicals. As a result of the competition between the polymer thickness and the F flux, the etch rate first increases and then decreases upon increasing the CF4 content. The electron properties, more specifically the electron density profile, affect the Si etch characteristics substantially by determining the radical density and flux profiles. In fact, the radial profile of the etch rate is more uniform at low CF4 content since the electron density has a smooth distribution. At high CF4 content, the etch rate is less uniform with a minimum halfway along the wafer radius, because the electron density distribution is more localized. Therefore, our calculations predict that it is better to work at relatively high Ar/CF4 gas ratios, in order to obtain high etch rate and good profile uniformity for etch applications. This, in fact, corresponds to the typical experimental etch conditions in Ar/CF4 gas mixtures as found in the literature, where Ar is typically present at a much higher concentration than CF4.

Zhao, Shu-Xia; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

2013-02-01

399

Safety issue of re-sterilization of polyurethane electrophysiology catheters: a cytotoxicity study.  

PubMed

The reuse of electrophysiology catheters could result in significant cost savings. However, re-sterilization of catheters could lead to several adverse consequences, including toxicity related to potential chemical reactions that occur during sterilization due to toxic residues remaining on the surface of catheters. The objective of this study was to investigate in vitro cytotoxicity of polyurethane (PU)-based catheter extracts on macrophages after their re-sterilization. We have compared three sterilization methods: steam autoclave, ethylene oxide (EtO) and hydrogen peroxide plasma (Sterrad system). Our results showed that the viability of cells varied from 90% to 99% as a function of incubation time and number of sterilization cycle. While there was no statistical difference based on the sterilization procedure, the number of sterilization cycles (up to 10 cycles) presents a statistically significant effect on the viability of J774 macrophages. However, extract obtained after resterilization of PU-based catheters had a low cytotoxic effect on J774 macrophages, since the overall cell mortality remained under 10%. An inhibitory effect on cell growth was also observed, which was not significant either as a function of incubation time, sterilization technique or the number of sterilization cycles. Finally, extracts of PU-based catheters had no statistically significant effect on TNF-alpha release by J774 macrophage. Even though there were some statistically significant differences between the control and processed samples, and among processed samples, our data suggest that one single reprocessing of PU-based catheters may not induce clinically significant changes in their cytotoxicity behaviour. PMID:12713095

Ma, Nan; Petit, Alain; Huk, Olga L; Yahia, L'Hocine; Tabrizian, Maryam

2003-01-01

400

Characteristics of hydrogen production of an Enterobacter aerogenes mutant generated by a new atmospheric and room temperature plasma (ARTP)  

Microsoft Academic Search

A novel atmospheric and room temperature plasma (ARTP) which used helium as the working gas was employed to generate mutants of Enterobacter aerogenes for improving the hydrogen production. For the mutation, 50?l of the E. aerogenes culture (OD600=2.0) was dipped onto a sterilized stainless steel plate (5mm in diameter). The plate was then treated for 3min by ARTP at the

Yuan Lu; Liyan Wang; Kun Ma; Guo Li; Chong Zhang; Hongxin Zhao; Qiheng Lai; He-Ping Li; Xin-Hui Xing

401

Male or female sterilization: a comparative study.  

PubMed

The study compares 709 males and 546 females recruited from a well-defined geographic area and sterilized during a 5-year period at the same hospital. Medical records were reviewed and questionnaires sent out. Widespread satisfaction with the sterilization was found. The sterilized women had experienced contraceptive side effects and failures more often than the men. Only 70% of the laparoscopic sterilizations could be carried out during a 1-day admission, 25% of the women complained about long-term sequelae, and there were 1% failures. The vasectomies were carried out on an outpatient basis, there were few postoperative symptoms, and 0.5% failures were recorded. Female sterilization was at least four times as expensive as vasectomy. It is concluded that vasectomy is generally to be preferred to female sterilization, and that the preoperative guidance should involve both man and wife. PMID:2920844

Kjersgaard, A G; Thranov, I; Rasmussen, O V; Hertz, J

1989-03-01

402

Surgical sterilization, regret, and race: Contemporary patterns.  

PubMed

Surgical sterilization is a relatively permanent form of contraception that has been disproportionately used by Black, Hispanic, and Native American women in the United States in the past. We use a nationally representative sample of 4592 women ages 25-45 to determine whether sterilization continues to be more common and consequential by race for reproductive-age women. Results indicate that Native American and Black women are more likely to be sterilized than non-Hispanic White women, and Hispanic and Native American women are more likely than non-Hispanic White women to report that their sterilization surgeries prevent them from conceiving children they want. Reasons for sterilization differ significantly by race. These findings suggest that stratified reproduction has not ended in the United States and that the patterns and consequences of sterilization continue to vary by race. PMID:25592919

Shreffler, Karina M; McQuillan, Julia; Greil, Arthur L; Johnson, David R

2015-03-01

403

Comparison of the surface characteristics of polypropylene films treated by Ar and mixed gas (Ar\\/O 2) atmospheric pressure plasma  

Microsoft Academic Search

In an attempt to modify the hydrophobic surface properties of polypropylene (PP) films, this study examined the optimum process parameters of atmospheric pressure plasma (APP) using Ar gas. Under optimized conditions, the effects of a mixed gas (Ar\\/O2) plasma treatment on the surface-free energy of a PP film were investigated as a function of the O2 content. The polar contribution

Oh-June Kwon; Sung-Woon Myung; Chang-Soo Lee; Ho-Suk Choi

2006-01-01

404

Preparation of Amorphous Fluorinated Carbon Film Using Low Global-Warming Potential Gas, C4F6, by Plasma Enhanced Chemical Vapor Deposition  

Microsoft Academic Search

Low-dielectric constant amorphous fluorinated carbon (a-C:F) films were prepared using plasma enhanced chemical vapor deposition (PECVD) from C4F6 gas, which is expected to be a substitutional gas due to its low global-warming potential (GWP). Kinetic analysis revealed that C4F6 (hexafluoro-1,3-butadiene) or related molecules were a main deposition precursor and that C4F6 concentration in the plasma affected the C-CF bond ratio

Hiroki Watanabe; Takumi Tokimitsu; Jyunko Shiga; Nobuo Haneji; Yukihiro Shimogaki

2006-01-01

405

Preparation and Characterization of Amorphous Fluorinated Carbon Film Using Low-Global-Warming-Potential Gas, C4F6, by Plasma-Enhanced Chemical Vapor Deposition  

Microsoft Academic Search

Low-dielectric-constant amorphous fluorinated carbon (a-C:F) films were prepared using plasma-enhanced chemical vapor deposition (PECVD) from C4F6 (hexafluoro-1,3-butadiene) gas, which is expected to be a substitutional gas owing to its low global warming potential (GWP). Kinetic analysis revealed that the density of C4F6 in plasma has a proportional relation to film growth rate, which suggests that C4F6 is a main deposition

Hiroki Watanabe; Yukihiro Shimogaki

2006-01-01

406

Performance evaluation of non-thermal plasma injection for elemental mercury oxidation in a simulated flue gas.  

PubMed

The use of non-thermal plasma (NTP) injection approach to oxidize elemental mercury (Hg(0)) in simulated flue gas at 110°C was studied, where a surface discharge plasma reactor (SDPR) inserted in the simulated flue duct was used to generate and inject active species into the flue gas. Approximately 81% of the Hg(0) was oxidized and 20.5?gkJ(-1) of energy yield was obtained at a rate of 3.9JL(-1). A maximal Hg(0) oxidation efficiency was found with a change in the NTP injection air flow rate. A high Hg(0) oxidation efficiency was observed in the mixed flue gas that included O2, H2O, SO2, NO and HCl. Chemical and physical processes (e.g., ozone, N2 metastable states and UV-light) were found to contribute to Hg(0) oxidation, with ozone playing a dominant role. The deposited mercury species on the internal surface of the flue duct was analyzed using X-ray photoelectron spectroscopy (XPS) and electronic probe microanalysis (EPMA), and the deposit was identified as HgO. The mercury species is thought to primarily exist in the form of HgO(s) by adhering to the suspended aerosols in the gas-phase. PMID:24513449

An, Jiutao; Shang, Kefeng; Lu, Na; Jiang, Yuze; Wang, Tiecheng; Li, Jie; Wu, Yan

2014-03-15

407

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

SciTech Connect

Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1?atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1?atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures.

Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady, E-mail: gennady@purdue.edu; Hassanein, Ahmed [Center for Materials Under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-04-15

408

An energy-efficient process for decomposing perfluorooctanoic and perfluorooctane sulfonic acids using dc plasmas generated within gas bubbles  

NASA Astrophysics Data System (ADS)

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are environmentally harmful and persistent substances. Their decomposition was investigated using dc plasmas generated within small gas bubbles in a solution. The plasma characteristics including discharge voltage, voltage drop in the liquid, plasma shape and the emission spectrum were examined with different gases. The decomposition rate and energy efficiency were evaluated by measuring the concentration of fluoride and sulfate ions released from PFOA/PFOS molecules. The concentration of fluoride ions and energy efficiency in the treatment of a PFOS solution were 17.7 mg l-1 (54.8% of the initial amount of fluorine atoms) and 26 mg kWh-1, respectively, after 240 min of operation. The addition of scavengers of hydroxyl radicals and hydrated electrons showed little effect on the decomposition. The decomposition processes were analyzed with an assumption that positive species reacted with PFOA/PFOS molecules at the boundary of the plasma-solution surface. This type of plasma showed a much higher decomposition energy efficiency compared with energy efficiencies reported in other studies.

Yasuoka, K.; Sasaki, K.; Hayashi, R.

2011-06-01

409

Heavy sterile neutrinos and supernova explosions  

E-print Network

We consider sterile neutrinos with rest masses ~0.2 GeV. Such sterile neutrinos could augment core collapse supernova shock energies by enhancing energy transport from the core to the vicinity of the shock front. The decay of these neutrinos could produce a flux of very energetic active neutrinos, detectable by future neutrino observations from a galactic supernova. The relevant range of sterile neutrino masses and mixing angles can be probed in future laboratory experiments.

George M. Fuller; Alexander Kusenko; Kalliopi Petraki

2008-06-26

410

Hysteroscopic Sterilization: History and Current Methods  

PubMed Central

For many practicing obstetrician-gynecologists, tubal ligation was the gold standard by which female sterilization techniques were measured. Yet gynecologic surgeons have simultaneously sought to occlude the fallopian tubes transcervically to avoid discomfort and complications associated with transabdominal approaches. In this review, the history of transcervical sterilization is discussed. Past, current, and upcoming techniques are reviewed. This article focuses on interval sterilization techniques, thus removing post-vaginal and post-cesarean delivery tubal ligations from the discussion. PMID:19015762

Greenberg, James A

2008-01-01

411

Quantum cascade laser investigations of CH4 and C2H2 interconversion in hydrocarbon/H2 gas mixtures during microwave plasma  

E-print Network

Quantum cascade laser investigations of CH4 and C2H2 interconversion in hydrocarbon/H2 gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond Jie Ma,1 Andrew Cheesman,1 Michael for plasma enhanced diamond chemical vapor deposition CVD have been investigated by line-of-sight infrared

Bristol, University of

412

Hysteroscopic sterilization in the office setting.  

PubMed

Hysteroscopic sterilization is growing in popularity. Nearly 500,000 women have been sterilized using this method, and an increasing number of physicians are now performing this procedure in the office setting. The office setting can provide a cost-effective, convenient, and safe environment for hysteroscopic sterilization. Patients may benefit from avoiding hospital preoperative visits, excessive laboratory evaluation, operating room wait times, and expense associated with hospital care. Physicians may improve productivity through remaining in their office or avoiding operating room delays. This article reviews office-hysteroscopic sterilization with the Essure microinsert system. PMID:24286995

Hodges, Kelly R; Swaim, Laurie S

2013-12-01

413

A novel low-jitter plasma-jet triggered gas switch operated at a low working coefficient.  

PubMed

In this paper, we described the fabrication and testing of a novel plasma-jet triggered gas switch (PJTGS) operated at extremely low working coefficients with excellent triggered jitters. While the structure of the PJTGS is similar to that of a traditional three-electrode field-distortion gas switch, to improve its triggered performance we used a conical micro-plasma-gun with a needle-to-plate spark gap embedded in the trigger electrode. Applying a nanosecond pulse to the trigger electrode caused a spark discharge in the micro-plasma-gun. The electric field drove the discharge plasma to spray into the spark gap of the gas switch, causing fast breakdown. We tested the PJTGS with charging voltages of ±25 kV and a trigger voltage of +80 kV (5 ns rise time and 80 ns full width at half maximum) in two working modes. The PJTGS operated in Mode II had a lower triggered jitter and could be operated over a wider range of working coefficients than in Mode I under the same conditions. At working coefficients higher than 70%, we obtained sub-ns triggered jitters (<0.89 ns) from the PJTGS, at working coefficients lower than 50%, we obtained triggered jitters of 1.6-3.5 ns without no-fires or pre-fires. Even at a working coefficient of 27.4%, the PJTGS could still be triggered reliably with a delay time of 96.1 ns and a triggered jitter of 3.5 ns, respectively. PMID:24593358

Tie, Weihao; Liu, Shanhong; Liu, Xuandong; Zhang, Qiaogen; Pang, Lei; Liu, Longchen

2014-02-01

414

[Gamma-rays and ethylene oxide sterilization (author's transl)].  

PubMed

For many years there was doubt if gamma-irradiated PVC materials could be sterilized with ethylene oxide. It was feared that toxic concentrations of ethylene chlorohydrin (2-chlorethanol) might originate with this procedure. We investigated the various possibilities of ethylene chlorohydrin formation. Gamma-irradiated PVC tubes were resterilized with ethylene oxide and the 2-chlorethanol concentrations determined by gas chromatography. The 2-chlorethanol concentrations at the end of sterilization ranged from 240 to 436 ppm depending upon the composition of the tubes. After 4 d they ranged from < 5 to 280 ppm and after 21 d from < 5 to 218 ppm. For comparison were examined PVC tubes which were not gamma-irradiated but ethylene oxide sterilized only. We extracted < 5 to 23 ppm ethylene chlorohydrin from them. PVC tubes gas sterilized only and retaining 44 to 9300 ppm ethylene oxide were submerged in physiological NaCl solution for 2 h. The ethylene chlorohydrin concentrations formed by this procedure ranged from 43 to 75 ppm. After 4 d aeration before begin of extraction they decreased to < 5, 10 and 16 ppm. PVC tubes aerated for 5 or 7 d, containing at least 236 ppm ethylene chlorohydrin did not demonstrate any effect upon cultures of human fibroblasts. The toxic concentrations of 2-chlorethanol in our own animal- and cell culture experiments were 12 000 ppm or higher. Other investigators found no damaging effect on mouse fibroblasts by adding 20 000 ppm ethylene chlorohydrin. It appears to be sufficiently proven that gamma-irradiated PVC items may be resterilized with ethylene oxide and used in patients provided they they have been adequately aerated. PMID:7434999

Star, E G

1980-06-01

415

Laboratory spectroscopic diagnostics of TLE-like air plasmas: methods to derive the rotational (gas) temperature in TLEs  

NASA Astrophysics Data System (ADS)

Laboratory low pressure (0.1 mbar < p < 2 mbar) glow air discharges have been studies by optical emission spectroscopy to illustrate several spectroscopic techniques that, depending on the available spectral resolution, could be implemented by different field spectrographs to experimentally quantify the gas temperature associated with Transient Luminous Events (TLEs) occurring at different altitudes including blue jets, giant blue jets and sprites. The laboratory air plasmas investigated have been analysed from the near UV (300 nm) to the near IR (1060 nm) with high (up to 0.01 nm) and low (2 nm) spectral resolution commercial grating spectrographs and by an in-house developed intensified CCD grating spectrograph that we have recently developed in our group at IAA - CSIC for TLE spectral diagnostic surveys with 0.45 nm spectral resolution. We discuss the results of laboratory tests and comment on the convenience of using one or another technique for rotational (gas) temperature determination during TLE spectroscopic campaigns. Finally, we will also show a comparison of the vibrational distribution function (VDF) of N2(B) obtained from (a) experiments in low pressure laboratory air plasmas produced in conditions similar to TLEs, (b) spectroscopic emissions from real TLE air plasmas and (c) compute from kinetic modeling.

Gordillo-Vazquez, F.; Parra-Rojas, F.; Passas, M.; Carrasco, E.; Luque, A.; Tanarro, I.; Simek, M.

2013-12-01

416

Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D  

SciTech Connect

Massive gas injection (MGI) experiments with H{sub 2}, D{sub 2}, He, Ne and Ar and 'mixed' (H{sub 2} + Ar and D{sub 2} + Ne) gases injected into 'ITER-similar' 1.3-MA H-mode plasmas are described. Gas species, injected quantity Q, delivery time, t{sub inj}, rate-of-rise and intrinsic and added impurities are found to affect the attributes and 'disruption mitigation' efficacies of the resulting fast plasma shutdowns. With sufficient Q and t{sub inj} < {approx}2 ms, all species provide fast (within {le} {approx}3 ms), more-or-less uniform radiative dissipation of the 0.7-MJ plasma thermal energy and fast but benign current decays with reduced vacuum vessel vertical force impulse. With pure and mixed low-Z gases, free-electron densities up to 2 x 10{sup 21} m{sup -3} are obtained. While these densities are high relative to normal tokamak densities, they are still an order of magnitude smaller than the densities required for unconditional mitigation of the runaway electron avalanche process. Key information relevant to the design of effective MGI systems for larger tokamaks and ITER has been obtained and the collective species and Q-variation data provides a rich basis for validation of emerging 2D + t MHD/transport/radiation models.

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

2008-10-14

417

Elevated plasma gas6 levels are associated with venous thromboembolic disease  

Microsoft Academic Search

Growth arrest-specific 6 (gas6), a novel vitamin K-dependent protein, has been demonstrated to have a role in thrombus stabilization\\u000a as gas6 null mice are resistant to lethal venous and arterial thrombosis. However, the association between gas6 and venous\\u000a thromboembolism has not been elucidated in humans. The present study aims to assess the role of gas6 in human venous thromboembolic\\u000a (VTE)

Mark D. Blostein; Isabelle Rajotte; Deepa P. Rao; Christina A. Holcroft; Susan R. Kahn

418

Exploration of the gas phase chemistry in microwave activated plasmas used  

E-print Network

. Two laser spectroscopy methods, cavity ring-down spectroscopy (CRDS) and tuneable infrared laser, and H(n=2) atoms, and their spatial profiles in CH4/Ar/H2 plasma, as functions of various discharge plasma, as functions of different discharge parameters. Actinometry was used to investigate the behaviour

Bristol, University of

419

Determination of the Gas Temperature of an Argon Microwave Plasma at Atmospheric Pressure Using van der Waals Broadening  

NASA Astrophysics Data System (ADS)

For the gas temperature determination for a discharge at atmospheric pressure, the ro-vibrational emission spectra of the molecular species are usually used, but exist cases when it is difficult to detect them. In order to analyze the possibility to use the van der Waals broadening of the neutral-argon lines to determine the gas temperature in an argon surface-wave sustained discharge (SWD) at atmospheric pressure, the values of the gas temperature inferred from the atomic lines with that ones obtained from the analysis of the OH molecular specie spectrum, were compared. If the Lorentzian broadening of a spectral line depends on axial position, this line is sensitive to the electron density variation. This is in particular the case for the 522.1, 549.6 and 603.2 nm lines. For this reason, these lines could be used to measure the electron density in discharges at atmospheric pressure. For these spectral lines a linear fit is obtained, which intersects the ordinate at a point corresponding to the Lorentzian width for zero electron density. This value can be considered approximately equal to the van der Waals width and is used here to calculate the plasma gas temperature. From our results and the comparison with other authors we can conclude that the method, proposed in this work, gives a possibility to estimate the gas temperature from the van der Waals broadening of atomic lines.

Yubero, Cristina; Dimitrijevi?, Milan S.; Garcia, Maria Carmen; Calzada, Maria Dolores

2007-09-01

420

Gas and electron temperature and density measurements from laser scattering from inductively coupled oxygen and nitrogen plasmas.  

NASA Astrophysics Data System (ADS)

The scattering of the second harmonic of a Nd:YAG laser (532nm) has been used to determine the electron and neutral gas energy distribution functions in an inductively coupled GEC reference reactor. The operating gases were oxygen, nitrogen and argon/oxygen and argon/nitrogen gas mixtures. The measured spectral profile of the laser light scatter from the centre of the discharge gap, at 90 degrees, to the incident beam direction contained components due to Thomson scattering from the plasma electrons and Rayleigh and Raman scattering from the gas atoms, molecules and ions. The latter indicated the extent of gas heating in the discharge with gas temperatures rising from 300 K to 1000K as the input power was increased from to 300W. The electron energy distribution function (eedfs) was determined from the Thomson scattering component. This indicates that the eedfs in nitrogen and oxygen are biMaxwellian with the bulk of the electrons at a temperature of 1 eV and a higher tail of about 5 eV.

Graham, Bill; Craig, Gary; Thompson, Catherine; Morrow, Tom; Steen, Philip

2004-09-01

421

The physical nature of the phenomenon of positive column plasma constriction in low-pressure noble gas direct current discharges  

SciTech Connect

The essence of the positive-column plasma constriction for static (the diffusion mode) and dynamic ionization equilibrium (the stratificated and constricted modes) is analyzed. Two physical parameters, namely, the effective ionization rate of gas atoms and the ambipolar diffusion coefficient of electrons and ions, determine the transverse distribution of discharge species and affect the current states of plasma. Transverse constriction of the positive column takes place as the gas ionization level (discharge current) and pressure increase. The stratified mode (including the constricted one) is observed between the two adjacent types of self-sustained discharge phases when they coexist together at the same time or in the same place as a coherent binary mixture. In the case, a occurrence of the discharge phase with more high electron density presently involve a great decrease in the cross-section of the current channel for d.c. discharges. Additional physical factors, such as cataphoresis and electrophoresis phenomena and spatial gas density inhomogeneity correlated with a circulatory flow in d.c. discharges, are mainly responsible for the current hysteresis and partially constricted discharge.

Kurbatov, P. F., E-mail: ion@laser.nsc.ru [Institute of Laser Physics SB RAS, Pr. Lavrentyev 13/3, 630090 Novosibirsk (Russian Federation)

2014-02-15

422

The physical nature of the phenomenon of positive column plasma constriction in low-pressure noble gas direct current discharges  

NASA Astrophysics Data System (ADS)

The essence of the positive-column plasma constriction for static (the diffusion mode) and dynamic ionization equilibrium (the stratificated and constricted modes) is analyzed. Two physical parameters, namely, the effective ionization rate of gas atoms and the ambipolar diffusion coefficient of electrons and ions, determine the transverse distribution of discharge species and affect the current states of plasma. Transverse constriction of the positive column takes place as the gas ionization level (discharge current) and pressure increase. The stratified mode (including the constricted one) is observed between the two adjacent types of self-sustained discharge phases when they coexist together at the same time or in the same place as a coherent binary mixture. In the case, a occurrence of the discharge phase with more high electron density presently involve a great decrease in the cross-section of the current channel for d.c. discharges. Additional physical factors, such as cataphoresis and electrophoresis phenomena and spatial gas density inhomogeneity correlated with a circulatory flow in d.c. discharges, are mainly responsible for the current hysteresis and partially constricted discharge.

Kurbatov, P. F.

2014-02-01

423

9 CFR 116.4 - Sterilization and pasteurization -records.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Sterilization and pasteurization -records. 116... RECORDS AND REPORTS § 116.4 Sterilization and pasteurization -records...or biological product subjected to sterilization or pasteurization. (Approved...

2010-01-01

424

42 CFR 441.255 - Sterilization by hysterectomy.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Sterilization by hysterectomy. 441.255 Section 441...AND LIMITS APPLICABLE TO SPECIFIC SERVICES Sterilizations § 441.255 Sterilization by hysterectomy. (a) FFP is not...

2010-10-01

425

42 CFR 50.207 - Sterilization by hysterectomy.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Sterilization by hysterectomy. 50.207...POLICIES OF GENERAL APPLICABILITY Sterilization of Persons in Federally Assisted...Planning Projects § 50.207 Sterilization by hysterectomy....

2010-10-01

426

7 CFR 305.23 - Steam sterilization treatment schedules.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Steam sterilization treatment schedules. 305.23 ...Heat Treatments § 305.23 Steam sterilization treatment schedules. Treatment schedule...lbs 20 Use 28? vacuum. Steam sterilization is not practical for treatment...

2010-01-01

427

21 CFR 872.6730 - Endodontic dry heat sterilizer.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false Endodontic dry heat sterilizer. 872.6730 Section 872...Devices § 872.6730 Endodontic dry heat sterilizer. (a) Identification. An endodontic dry heat sterilizer is a device intended to...

2011-04-01

428

21 CFR 872.6730 - Endodontic dry heat sterilizer.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Endodontic dry heat sterilizer. 872.6730 Section 872...Devices § 872.6730 Endodontic dry heat sterilizer. (a) Identification. An endodontic dry heat sterilizer is a device intended to...

2010-04-01

429

21 CFR 872.6730 - Endodontic dry heat sterilizer.  

... 2014-04-01 false Endodontic dry heat sterilizer. 872.6730 Section 872...Devices § 872.6730 Endodontic dry heat sterilizer. (a) Identification. An endodontic dry heat sterilizer is a device intended to...

2014-04-01

430

21 CFR 872.6730 - Endodontic dry heat sterilizer.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Endodontic dry heat sterilizer. 872.6730 Section 872...Devices § 872.6730 Endodontic dry heat sterilizer. (a) Identification. An endodontic dry heat sterilizer is a device intended to...

2012-04-01

431

21 CFR 872.6730 - Endodontic dry heat sterilizer.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Endodontic dry heat sterilizer. 872.6730 Section 872...Devices § 872.6730 Endodontic dry heat sterilizer. (a) Identification. An endodontic dry heat sterilizer is a device intended to...

2013-04-01

432

Degradation of poly(vinyl chloride) plasticized with non-phthalate plasticizers under sterilization conditions  

Microsoft Academic Search

Plasticized PVC formulations have traditionally been used in the production of medical devices, such as tubes and bags for plasma or blood because of their good performance in mechanical and thermal properties as well as their low cost. Clinical practice, in particular re-use after sterilization, can damage and promote degradation of these materials with the risk of release of polymer

Nuria Burgos; Alfonso Jiménez

2009-01-01

433

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

Microsoft Academic Search

Among the various industrial uses of the glow discharge at atmospheric pressure (GDAP), biological applications such as sterilization are under investigation. In this paper, we present images of a liquid medium (Luria-Bertani broth with tetracycline) contaminated by Escherichia coli bacteria (strain PER 322) undergoing plasma treatment. In most cases, it is found that an exposure time of two to 20

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

1999-01-01

434

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  

NASA Astrophysics Data System (ADS)

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 highest amount of trimethylarsine (121 ?g/L (As)) was found in the pressurized condensate, along with trace amounts of non-identified higher alkylated arsines. Volatile arsenic species in natural gas and its related products cause concern with regards to environment, safety, occupational health and gas processing. Therefore, interest lies in a fast and simple field method for the determination of volatile arsenicals. Here, we use simple liquid and solid sorption techniques, namely absorption in silver nitrate solution and adsorption on silver nitrate impregnated silica gel tubes followed by total arsenic determination as a promising tool for field monitoring of volatile arsenicals in natural gas and gas condensates. Preliminary results obtained for the sorption-based methods show that around 70% of the arsenic is determined with these methods in comparison to volatile arsenic determination using GC-ICP-MS. Furthermore, an inter-laboratory- and inter-method comparison was performed using silver nitrate impregnated silica tubes on 14 different gas samples with concentrations varying from below 1 to 1000 ?g As/m 3 natural gas. The results obtained from the two laboratories differ in a range of 10 to 60%, but agree within the order of magnitude, which is satisfactory for our purposes.

Krupp, E. M.; Johnson, C.; Rechsteiner, C.; Moir, M.; Leong, D.; Feldmann, J.

2007-09-01

435

Optimization of a gas discharge plasma source for extreme ultraviolet interference lithography at a wavelength of 11 nm  

SciTech Connect

In this work, we report about the optimization of the spectral emission characteristic of a gas discharge plasma source for high-resolution extreme ultraviolet (EUV) interference lithography based on achromatic Talbot self-imaging. The working parameters of the source are optimized to achieve a required narrowband emission spectrum and to fulfill the necessary coherence and intensity requirements. The intense 4f-4d transitions around 11 nm in a highly ionized (Xe{sup 8+}-Xe{sup 12+}) xenon plasma are chosen to provide the working wavelength. This allows us to increase the available radiation intensity in comparison with an in-band EUV xenon emission at 13.5 nm and opens up the possibility to strongly suppress the influence of the 5p-4d transitions at wavelengths between 12 and 16 nm utilizing a significant difference in conditions for optical thickness between 4f-4d and 5p-4d transitions. The effect is achieved by using the admixture of argon to the pinch plasma, which allows keeping the plasma parameters approximately constant while, at the same time, reducing the density of xenon emitters. It is demonstrated that with this approach it is possible to achieve a high intensity 11 nm EUV radiation with a bandwidth of 3%-4% without the use of multilayer mirrors or other additional spectral filters in the vicinity of the working wavelength. The achieved radiation parameters are sufficient for high-performance interference lithography based on the achromatic Talbot effect.

Bergmann, K. [Fraunhofer Institute for Laser Technology, Steinbachstrasse 15, D-52074 Aachen (Germany); Danylyuk, S. V.; Juschkin, L. [Chair for Technology of Optical Systems, RWTH Aachen University and JARA Fundamentals of Future Information Technology, Steinbachstr. 15, 52074 Aachen (Germany)

2009-10-01

436

Optimization of a gas discharge plasma source for extreme ultraviolet interference lithography at a wavelength of 11 nm  

NASA Astrophysics Data System (ADS)

In this work, we report about the optimization of the spectral emission characteristic of a gas discharge plasma source for high-resolution extreme ultraviolet (EUV) interference lithography based on achromatic Talbot self-imaging. The working parameters of the source are optimized to achieve a required narrowband emission spectrum and to fulfill the necessary coherence and intensity requirements. The intense 4f-4d transitions around 11 nm in a highly ionized (Xe8+-Xe12+) xenon plasma are chosen to provide the working wavelength. This allows us to increase the available radiation intensity in comparison with an in-band EUV xenon emission at 13.5 nm and opens up the possibility to strongly suppress the influence of the 5p-4d transitions at wavelengths between 12 and 16 nm utilizing a significant difference in conditions for optical thickness between 4f-4d and 5p-4d transitions. The effect is achieved by using the admixture of argon to the pinch plasma, which allows keeping the plasma parameters approximately constant while, at the same time, reducing the density of xenon emitters. It is demonstrated that with this approach it is possible to achieve a high intensity 11 nm EUV radiation with a bandwidth of 3%-4% without the use of multilayer mirrors or other additional spectral filters in the vicinity of the working wavelength. The achieved radiation parameters are sufficient for high-performance interference lithography based on the achromatic Talbot effect.

Bergmann, K.; Danylyuk, S. V.; Juschkin, L.

2009-10-01

437

Comparison of Gas Sensors Based on Oxygen Plasma-Treated Carbon Nanotube Network Films with Different Semiconducting Contents  

NASA Astrophysics Data System (ADS)

We report on the effect of oxygen plasma treatment on the performance of single-wall carbon nanotube (SWCNT) NH3 gas sensors with different semiconducting contents (66% and 90% semiconducting SWCNTs). The performance of chemical sensors based on SWCNT networks depends on the concentration of semiconducting SWCNTs (s-SWCNTs), whose conductance can be significantly modulated by the absorbed molecules and the surface functionalization. After oxygen plasma treatment, the 66% s-SWCNT sample showed an increase in sensitivity from 0.0275%/ppm to 0.1525%/ppm (5.5 times), while the 90% s-SWCNT device demonstrated an increase in sensitivity from 0.1184%/ppm to 1.5707%/ppm (13 times). These results correspond to improvements in sensitivity of 57 times and 10 times compared with pristine and plasma-treated 66% s-SWCNT samples, respectively. In addition, the plasma-treated sensors exhibited much faster response and recovery times than the pristine one. The large improvement in performance was explained by the presence of oxygen-containing functional groups and the sp2-sp3 structure change of SWCNTs, which changes the binding energy while increasing the uptake of polar molecules such as NH3.

Ham, Seung Woo; Hong, Hyun Pyo; Kim, Jin Woong; Kim, Jong Hyun; Kim, Ki Bum; Park, Chan Won; Min, Nam Ki

2015-01-01

438