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1

Townsend First Coefficient in Argon, Xenon and Their Mixture.  

National Technical Information Service (NTIS)

The ionization coefficient of alpha /P as a function of E/P is determined for argon, xenon and the Ar+0.5% Xe mixture at pressure up to 100 atm. ( alpha - Townsend coefficient, P - gas pressure, E - electric field strength). The findings differ essentiall...

V. K. Dodoknov V. A. Zhukov

1980-01-01

2

Xenon Anesthesia Improves Respiratory Gas Exchanges in Morbidly Obese Patients  

PubMed Central

Background. Xenon-in-oxygen is a high density gas mixture and may improve PaO2/FiO2 ratio in morbidly obese patients uniforming distribution of ventilation during anesthesia. Methods. We compared xenon versus sevoflurane anesthesia in twenty adult morbidly obese patients (BMI > 35) candidate for roux-en-Y laparoscopic gastric bypass and assessed PaO2/FiO2 ratio at baseline, at 15?min from induction of anaesthesia and every 60?min during surgery. Differences in intraoperative and postoperative data including heart rate, systolic and diastolic pressure, oxygen saturation, plateau pressure, eyes opening and extubation time, Aldrete score on arrival to the PACU were compared by the Mann-Whitney test and were considered as secondary aims. Moreover the occurrence of side effects and postoperative analgesic demand were assessed. Results. In xenon group PaO2-FiO2 ratio was significantly higher after 60?min and 120?min from induction of anesthesia; heart rate and overall remifentanil consumption were lower; the eyes opening time and the extubation time were shorter; morphine consumption at 72?hours was lower; postoperative nausea was more common. Conclusions. Xenon anesthesia improved PaO2/FiO2 ratio and maintained its distinctive rapid recovery times and cardiovascular stability. A reduction of opioid consumption during and after surgery and an increased incidence of PONV were also observed in xenon group.

Abramo, Antonio; Di Salvo, Claudio; Foltran, Francesca; Forfori, Francesco; Anselmino, Marco; Giunta, Francesco

2010-01-01

3

A xenon gas purity monitor for EXO  

NASA Astrophysics Data System (ADS)

We discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices are sensitive to concentrations of oxygen well below 1 ppb at an ambient gas pressure of one atmosphere or more. The theory of operation of the GPM is discussed along with the interactions of oxygen and other impurities with the GPM's tungsten filament. Lab tests and experiences in commissioning the EXO-200 double beta decay experiment are described. These devices can also be used on other noble gases.

Dobi, A.; Hall, C.; Herrin, S.; Odian, A.; Prescott, C. Y.; Rowson, P. C.; Ackerman, N.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Barry, K.; Benitez-Medina, C.; Breidenbach, M.; Cook, S.; Counts, I.; Daniels, T.; DeVoe, R.; Dolinski, M. J.; Donato, K.; Fairbank, W.; Farine, J.; Giroux, G.; Gornea, R.; Graham, K.; Gratta, G.; Green, M.; Hagemann, C.; Hall, K.; Hallman, D.; Hargrove, C.; Karelin, A.; Kaufman, L. J.; Kuchenkov, A.; Kumar, K.; Lacey, J.; Leonard, D. S.; LePort, F.; Mackay, D.; MacLellan, R.; Mong, B.; Montero Díez, M.; Müller, A. R.; Neilson, R.; Niner, E.; O'Sullivan, K.; Piepke, A.; Pocar, A.; Pushkin, K.; Rollin, E.; Sinclair, D.; Slutsky, S.; Stekhanov, V.; Twelker, K.; Voskanian, N.; Vuilleumier, J.-L.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

2011-12-01

4

Investigation of a Possibility of Application of NiSiO2 Adsorbent to Long Time Diffusion Purification of Xenon- and Methan Mixture.  

National Technical Information Service (NTIS)

The possibility of application of Ni/SiO/sub 2/ adsorbent for long duration purification of xenon in gas filled detectors was investigated. It is shown that diffusion purification of xenon and its mixtures by means of Ni/SiO/sub 2/ allows to keep the leve...

Y. V. Zanevskij V. D. Peshekhonov L. P. Smykov

1988-01-01

5

XENON  

Microsoft Academic Search

The XENON experiment aims at the direct detection of dark matter in the form of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering off Xenon nuclei. With 1 ton of LXe distributed in ten identical modules, the proposed XENON1T experiment will achieve a sensitivity more than a factor of thousand beyond current limits.The detectors are time projection chambers operated

E. Aprile; K.-L. Giboni; M. E. Monzani; G. Plante; M. Yamashita; R. J. Gaitskell; S. Fiorucci; P. Sorensen; L. Deviveiros; A. Bernstein; N. Madden; C. Winant; T. Shutt; J. Kwong; A. Bolozdynya; E. Dahl; U. Oberlack; P. Shagin; R. Gomez; D. McKinsey; A. Manzur; R. Hasty; K. Ni; F. Arneodo; A. Ferella; L. Baudis; J. Angle; J. Orboeck; A. Manalaysay; J. A. M. Lopes; L. Coelho; L. Fernandes; J. Santos

2007-01-01

6

Secondary shock formation in xenon-nitrogen mixtures  

SciTech Connect

The expansion of shock waves has been studied in mediums with different opacities and heat capacities, varied in systematic ways by mixing xenon with nitrogen keeping the mass density constant. An initial shock is generated through the brief (5 ns) deposition of laser energy (5 J) on the tip of a pin surrounded by the xenon-nitrogen mixture. The initial shock is spherical, radiative, with a high Mach number, and it sends a supersonic radiatively driven heat wave far ahead of itself. The heat wave rapidly slows to a transonic regime and when its Mach number drops to {approx}2 with respect to the downstream plasma, the heat wave becomes of the ablative type, driving a second shock ahead of itself to satisfy mass and momentum conservation in the heat wave reference frame. The details of this sequence of events depend, among other things, on the opacity and heat capacity of the surrounding medium. Second shock formation is observed over the entire range from 100% Xe mass fraction to 100% N{sub 2}. The formation radius of the second shock as a function of Xe mass fraction is consistent with an analytical estimate.

Hansen, J. F.; Edwards, M. J.; Froula, D. H.; Edens, A. D.; Gregori, G.; Ditmire, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Sandia National Labs, Albuquerque, New Mexico 87185 (United States); LRC-Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); University of Texas at Austin, Austin, Texas 78712 (United States)

2006-11-15

7

Hyperpolarized xenon NMR and MRI signal amplification by gas extraction  

PubMed Central

A method is reported for enhancing the sensitivity of NMR of dissolved xenon by detecting the signal after extraction to the gas phase. We demonstrate hyperpolarized xenon signal amplification by gas extraction (Hyper-SAGE) in both NMR spectra and magnetic resonance images with time-of-flight information. Hyper-SAGE takes advantage of a change in physical phase to increase the density of polarized gas in the detection coil. At equilibrium, the concentration of gas-phase xenon is ?10 times higher than that of the dissolved-phase gas. After extraction the xenon density can be further increased by several orders of magnitude by compression and/or liquefaction. Additionally, being a remote detection technique, the Hyper-SAGE effect is further enhanced in situations where the sample of interest would occupy only a small proportion of the traditional NMR receiver. Coupled with targeted xenon biosensors, Hyper-SAGE offers another path to highly sensitive molecular imaging of specific cell markers by detection of exhaled xenon gas.

Zhou, Xin; Graziani, Dominic; Pines, Alexander

2009-01-01

8

Hydrodynamic gas mixture separation  

Microsoft Academic Search

The separation of gas mixtures is the basis of many chemical, petrochemical, and gas processes. Classical separation methods (absorption, adsorption, condensation, and freezing) require cumbersome and complex equipment. No adequate solution is provided by the cheapening and simplification of gas-processing apparatus and separation methods by hydration and diffusion. For example, an apparatus for extracting helium from natural gas by diffusion

Stolyarov

1982-01-01

9

Review of Helium and Xenon Pure Component and Mixture Transport Properties and Recommendation of Estimating Approach for Project Prometheus (Viscosity and Thermal Conductivity)  

SciTech Connect

The selected configuration for the Project Prometheus Space Nuclear Power Plant was a direct coupling of Brayton energy conversion loop(s) to a single reactor heat source through the gas coolant/working fluid. A mixture of helium (He) and xenon (Xe) gas was assumed as the coolant/working fluid. Helium has superior thermal conductivity while xenon is added to increase the gas atomic weight to benefit turbomachinery design. Both elements have the advantage of being non-reactive. HeXe transport properties (viscosity and thermal conductivity) were needed to calculate pressure drops and heat transfer rates. HeXe mixture data are limited, necessitating the use of semi-empirical correlations to calculate mixture properties. Several approaches are available. Pure component properties are generally required in the mixture calculations. While analytical methods are available to estimate pure component properties, adequate helium and xenon pure component data are available. This paper compares the sources of pure component data and the approaches to calculate mixture properties. Calculated mixture properties are compared to the limited mixture data and approaches are recommended to calculate both pure component and mixture properties. Given the limited quantity of HeXe mixture data (all at one atmosphere), additional testing may have been required for Project Prometheus to augment the existing data and confirm the selection of mixture property calculation methods.

Haire, Melissa A.; Vargo, David D. [Bechtel Bettis, Inc., Bettis Atomic Power Laboratory, P.O. Box 79, West Mifflin, PA 15122 (United States)

2007-01-30

10

Gas-phase silicon micromachining with xenon difluoride  

Microsoft Academic Search

Xenon difluoride is a gas phase, room temperature, isotropic silicon etchant with extremely high selectivity to many materials commonly used in microelectromechancial systems, including photoresists, aluminum, and silicon dioxide. Using a simple vacuum system, the effects of etch aperture and loading were explored for etches between 10 and 200 micrometers . Etch rates as high as 40 micrometers \\/minute were

Floy I. Chang; Richard Yeh; Gisela Lin; Patrick B. Chu; Eric G. Hoffman; Ezekiel J. Kruglick; Kristofer S. Pister; Michael H. Hecht

1995-01-01

11

Low Mass WIMP Search Using High Pressure Xenon Gas  

NASA Astrophysics Data System (ADS)

Several groups around the globe employ unique detector technologies in the direct search for dark matter weakly interacting massive particles (WIMPs). One of the leading technologies uses scintillation and ionization signals produced when WIMPs scatter off xenon nuclei. Recent compelling results hint at the possibility of a less massive WIMP (7 -- 10 GeV/c^2), than was previously thought. A plan will be presented for a low mass WIMP search using high pressure xenon, and possibly neon gas. The design, calibration, and expected results will be discussed.

Sofka, Clement

2012-10-01

12

Gas Phase Xenon131 Quadrupolar Splitting at High Magnetic Fields  

Microsoft Academic Search

At very high magnetic fields strengths (14 Tesla and higher) the xenon-131 gas phase NMR spectrum shows a well resolved quadrupolar splitting. Quadrupolar coupling between a non-spherical (S>1\\/2) nuclei and an electric field gradient will occur when the electrical isotropy of the surrounding electron cloud is disturbed. The experimental results suggest that the origin of the observed splitting in the

Thomas Meersmann

1998-01-01

13

Separation of gas mixtures by thermoacoustic waves.  

SciTech Connect

Imposing sound on a binary gas mixture in a duct separates the two gases along the acoustic-propagation axis. Mole-fraction differences as large as 10% and separation fluxes as high as 0.001 M-squared c, where M is Mach number and c is sound speed, are easily observed. We describe the accidental discovery of this phenomenon in a helium-xenon mixture, subsequent experiments with a helium-argon mixture, and theoretical developments. The phenomenon occurs because a thin layer of the gas adjacent to the wall is immobilized by viscosity while the rest of the gas moves back and forth with the wave, and the heat capacity of the wall holds this thin layer of the gas at constant temperature while the rest of the gas experiences temperature oscillations due to the wave's oscillating pressure. The oscillating temperature gradient causes the light and heavy atoms in the gas to take turns diffusing into and out of the immobilized layer, so that the oscillating motion of the wave outside the immobilized layer tends to carry light-enriched gas in one direction and heavy-enriched gas in the opposite direction. Experiment and theory are in very good agreement for the initial separation fluxes and the saturation mole-fraction differences.

Swift, G. W. (Gregory W.); Geller, D. A. (Drew A.)

2001-01-01

14

Micromegas-TPC operation at high pressure in Xenon-trimethylamine mixtures  

NASA Astrophysics Data System (ADS)

We present in this work measurements performed with a small Micromegas-TPC using a xenon-trimethylamine (Xe-TMA) Penning-mixture as filling gas. Measurements of gas gain and energy resolutions for 22.1 keV X-rays are presented, spanning several TMA concentrations and pressures between 1 and 10 bar. Across this pressure range, the best energy resolution and largest increase in gain at constant field (a standard figure for characterizing Penning-like energy transfers) is observed within the 0.9%-1.7% TMA range. A gain increase (at constant field) up to a factor 100 and best values of the energy resolution improved by up to a factor 3 with respect to the one previously reported in pure Xe -operated Micromegas, can be obtained. In virtue of the VUV-quenching properties of the mixture, the overall maximum gain achievable is also notably increased (up to 400 at 10bar), a factor ×3 higher than in pure Xe. In addition, preliminary measurements of the electron drift velocity in a modified setup have been performed and show good agreement with the one obtained from Magboltz. These results are of great interest for calorimetric applications in gas Xe TPCs, in particular for the search of the neutrino-less double beta decay (0???) of 139Xe. It is important to note that in this work some figures from [1] have been updated. Precisely, the TMA concentration has been re-estimated after a detailed re-calibration of the mass spectrometer yielding lower TMA concentration values, corrected by a factor in the range 0.5 - 0.7. An erratum to [1] is being submitted at the moment of writing.

Herrera, D. C.; Cebrián, S.; Dafni, T.; Ferrer-Ribas, E.; Giomataris, I.; Gonzalez-Diaz, D.; Gómez, H.; Iguaz, F. J.; Irastorza, I. G.; Luzon, G.; Rodríguez, A.; Segui, L.; Tomás, A.

2013-10-01

15

Numerical model of an ac plasma display panel cell in neon-xenon mixtures  

Microsoft Academic Search

We present a self-consistent 1D model of the discharge initiated in an ac plasma display panel cell. The model is based on a two-moments fluid description of electron and ion transport, coupled with Poisson’s equation, and with a set of kinetic equations characterizing the evolution of the population of excited states leading to UV emission in neon-xenon mixtures. Results are

J. Meunier; Ph. Belenguer; J. P. Boeuf

1995-01-01

16

Helium, neon, argon, krypton and xenon in gas emanations from Yellowstone and Lassen volcanic National Parks  

Microsoft Academic Search

The abundance of helium, neon, argon, krypton and xenon were measured in gas emanations from thermal springs in Yellowstone National Park, Wyoming and Lassen National Park, California. The determinations were made using an isotope dilution procedure. The isotopic composition of argon and the relative abundances of argon, neon, krypton and xenon indicate that these gases originated from the atmosphere through

E. Mazor; G. J. Wasserburg

1965-01-01

17

New gas mixtures suitable for rare event detection using a Micromegas-TPC detector  

Microsoft Academic Search

The aim of the presented work was to develop further techniques based on a Micromegas-TPC, in order to reach a high gas gain with good energy resolution, and to search for gas mixtures suitable for rare event detection. This paper focuses on Xenon, which is convenient for the search of neutrinoless double beta decay in 136Xe, and CF4, suitable for

L. Ounalli; J-L Vuilleumier; D Schenker; J. M. Vuilleumier

2009-01-01

18

Human Regional Pulmonary Gas Exchange with Xenon Polarization Transfer (XTC)  

NASA Astrophysics Data System (ADS)

Xenon Transfer Contrast (XTC) is an existing imaging method (Ruppert et al, Magn Reson Med, 51:676-687, 2004) that measures the fraction F of ^129Xe magnetization that diffuses from alveolar gas spaces to septal parenchymal tissue in lungs in a specified exchange time. As previously implemented, XTC is a 2-breath method and has been demonstrated in anesthetized animals. To use XTC in humans and to avoid issues associated with obtaining identical gas volumes on subsequent breath-hold experiments as well as precise image registration in post-processing, a single breath XTC method was developed that acquires three consecutive gradient echo images in an 8s acquisition. We report here initial measurements of the mean and variance of F for 5 normal healthy subjects as well as 7 asymptomatic smokers. The experiments were performed at two lung volumes (˜45 and 65% of TLC). We found that both the mean and variance of F increased with smoking history. In comparison, standard pulmonary function tests such as DLCO FEV1 showed no correlation with smoking history.

Muradian, Iga; Butler, James; Hrovat, Mirko; Topulos, George; Hersman, Elizabeth; Ruset, Iulian; Covrig, Silviu; Frederick, Eric; Ketel, Stephen; Hersman, F. W.; Patz, Samuel

2007-03-01

19

Neuroprotective and neurotoxic properties of the 'inert' gas, xenon  

Microsoft Academic Search

Background. Antagonists of the N-methyl-D-aspartate (NMDA) subtype of glutamate recep- tors have been shown not only to have neuroprotective effects but also to exhibit neurotoxic properties. In this study, we used c-Fos, a protein product of an immediate early gene, as a marker of neuronal injury to compare the neuroprotective effects of xenon and the neurotoxic properties of xenon, nitrous

D. Ma; S. Wilhelm; M. Maze; N. P. Franks

2002-01-01

20

[Effects of xenon and krypton-containing breathing mixtures on clinical and biochemical blood indices in animals].  

PubMed

Effects of 24-hr breathing air mixtures containing xenon (XBM) and krypton (KBM) were compared in terms of hormonal status, and blood biochemical indices and morphology in laboratory animals. Some changes observed in blood and hormone indices could be a nonspecific adaptive response. Hence, we should elicit whether these effects are quickly reversible or long. For several indices krypton was a more favorable factor than xenon. However, some of its effects invite to delve into effects of different krypton concentrations on organism. PMID:17682508

Kussmaul', A R; Bogacheva, M A; Shkurat, T P; Pavlov, B N

21

TEA laser gas mixture optimization  

SciTech Connect

The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO/sub 2/ TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.

Lipchak, W.M.; Luck, C.F.

1982-11-01

22

Ionization coefficients in gas mixtures  

NASA Astrophysics Data System (ADS)

We have tested the application of the common E/N (E—electric field, N—gas number density) or Wieland approximation [Van Brunt, R.J., 1987. Common parametrizations of electron transport, collision cross section, and dielectric strength data for binary gas mixtures. J. Appl. Phys. 61 (5), 1773 1787.] and the common mean energy (CME) combination of the data for pure gases to obtain ionization coefficients for mixtures. Test calculations were made for Ar CH4, Ar N2, He Xe and CH4 N2 mixtures. Standard combination procedure gives poor results in general, due to the fact that the electron energy distribution is considerably different in mixtures and in individual gases at the same values of E/N. The CME method may be used for mixtures of gases with ionization coefficients that do not differ by more than two orders of magnitude which is better than any other technique that was proposed [Mari?, D., Radmilovi?-Ra?enovi?, M., Petrovi?, Z.Lj., 2005. On parametrization and mixture laws for electron ionization coefficients. Eur. Phys. J. D 35, 313 321.].

Mari?, D.; Šaši?, O.; Jovanovi?, J.; Radmilovi?-Ra?enovi?, M.; Petrovi?, Z. Lj.

2007-03-01

23

Drift velocity and gain in argon- and xenon-based mixtures  

NASA Astrophysics Data System (ADS)

We present measurements of drift velocities and gains in gas mixtures based on Ar and Xe, with CO2, CH4, and N2 as quenchers, and compare them with calculations. In particular, we show the dependence of Ar- and Xe-CO2 drift velocities and gains on the amount of nitrogen contamination in the gas, which in real experiments may build up through leaks. A quantification of the Penning mechanism which contributes to the Townsend coefficients of a given gas mixture is proposed.

Andronic, A.; Biagi, S.; Braun-Munzinger, P.; Garabatos, C.; Tsiledakis, G.

2004-05-01

24

Nuclear excited xenon flashlamp  

SciTech Connect

The optical emissions of nuclear excited Xenon plasmas were investigated to determine basic parameters important to photolytic pumping of lasers. Gas mixtures of Helium-3 and Xenon were irradiated in the steady state mode in the University of Florida Training Reactor at neutron flux levels of about 10/sup 12//cm/sup 2/.s, generating a power density in the gas of approximately 3 milliwatts/cm/sup 3/. Optical emissions from the gas were primarily due to Xe/sub 2/* band emission at 172 nm with a few Xell lines in the visible and ir. Energy transfer from the /sup 3/He(n,p)T reaction to the Xe/sub 2/* 172 nm band was 67.0% +- 10%. High pressure gas mixtures (4 atm.) of Helium-3 and Xenon were irradiated in the pulse mode (250 ..mu..s FWHM) at the fast burst reactor at the Aberdeen Pulsed Radiation Facility at thermal neutron flux levels of about 10/sup 17//cm/sup 2/.s, generating a power density in the gas of about 1 kilowatt/cm/sup 3/. Optical emissions from the gas extended from the vacuum ultraviolet through the visible to the infrared, resembling a discharge excited lamp with a current density of about 1500 amp./cm/sup 2/. Such a lamp could pump a Neodymium YAG or liquid laser.

Cox, J.D.

1982-01-01

25

Scintillation Light, Ionization Yield and Scintillation Decay Times in High Pressure Xenon and Xenon Methane  

Microsoft Academic Search

Scintillation light, ionization yield and scintillation decay times have been measured in xenon and in its mixture with a 0.05% concentration of methane as a function of the reduced electric field (E\\/N)-the ratio of the electric field strength to the number density of gas-at a pressure of 21 atm. The measurements of scintillation decay times in the xenon-methane mixture have

K. N. Pushkin; D. Y. Akimov; A. A. Burenkov; V. V. Dmitrenko; A. G. Kovalenko; V. N. Lebedenko; I. S. Kuznetsov; V. N. Stekhanov; C. Tezuka; S. E. Ulin; Z. M. Uteshev; K. F. Vlasik

2007-01-01

26

Detection of residual krypton in xenon gas for WIMP dark matter searches  

NASA Astrophysics Data System (ADS)

The next generation of WIMP dark matter searches using liquid xenon as a target medium will require unprecedented rejection of residual krypton contamination. Krypton contains the beta emitting isotope ^85Kr, with a relative abundance of about 10-11 (^85Kr/^natKr), and this beta decay can be an important source of background for these experiments. Krypton is typically present in commercially produced xenon at the level of tens of parts-per-billion, about four orders of magnitude too large for present day dark matter experiments such as XENON, LUX, and XMASS. Additional processing via gas chromatography and distillation are used to separate krypton from xenon, but measuring the remaining krypton level at the part-per-trillion (ppt) level is challenging. Recently we have developed a highly sensitive and simple technique to measure residual krypton contamination in xenon gas using an RGA mass spectrometer and a liquid nitrogen cold trap. We describe here the results of our calibration experiments to determine the ultimate limit of detection of the method, and we discuss the implications for the next generation of WIMP dark matter experiments.

Dobi, Attila

2011-04-01

27

Characterization of gas condensate mixtures  

SciTech Connect

Simulation of the phase behavior of gas condensate mixtures is a severe test of the employed equation of state and of the C/sub 7+/ - characterization procedure. This paper presents experimental and calculated results for the phase behavior of different gas condensate mixtures, one of which is near critical reservoir conditions. The calculations are based on the Soave-Redlich-Kwong equation of state. For the plus-fraction a continuous logarithmic dependence is assumed for the mole fraction against carbon number. The critical properties of the C/sub 7+/-fractions are calculated directly from measured physical properties of the fractions (molecular weight and density). The procedure is fully predictive. Accurate results are obtained for the phase properties and for the phase compositions. The model may be used successfully also for heavy oil mixtures. It is shown that deviations between the measured and calculated results often can be related to inaccuracies of the data related to the composition in particular of the results for the molecular weight of the plus fraction.

Pedersen, K.S. (CALSEP A/S, Lyngby Hovedgade 29, Dk-2800 Lyngby (DK)); Thomassen, P. (STATOIL, Forus, Postboks 300, N-4001 Stavanger (NO)); Fredenslund, A. (The Technical Univ. of Demark, Dk-2800 Lyngby (DK))

1988-01-01

28

Gas mixtures for spark gap closing switches  

DOEpatents

Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

1987-02-20

29

Gas mixtures for spark gap closing switches  

DOEpatents

Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches.

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Hunter, Scott R. (Oak Ridge, TN)

1988-01-01

30

Intelligent gas-mixture flow sensor  

Microsoft Academic Search

A simple way to realize a gas-mixture flow sensor is presented. The sensor is capable of measuring two parameters from a gas flow. Both the flow rate and the helium content of a helium-nitrogen gas mixture are measured. The sensor exploits two measurement principles in combination with (local) information handling in an artificial neural network. An analysis of the measurement

Theo S. J. Lammerink; Fred Dijkstra; Zweitze Houkes; Joost van Kuijk

1995-01-01

31

Luminescence evidence for bulk and surface excitons in free xenon clusters  

SciTech Connect

The cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying the initial experimental parameters, including the xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters ({approx_equal}1500 atoms). The cluster size and temperature ({approx_equal}40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. The presence of an argon shell causes extinction of the excitonic bands. In addition, some bands were found which have no analogs for bulk xenon cryosamples.

Danylchenko, O. G.; Doronin, Yu. S.; Kovalenko, S. I.; Libin, M. Yu.; Samovarov, V. N.; Vakula, V. L. [B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Avenue, Kharkiv, 61103 (Ukraine)

2007-10-15

32

Detection of Alpha Particles and Low Energy Gamma Rays by Thermo-Bonded Micromegas in Xenon Gas  

NASA Astrophysics Data System (ADS)

Micromegas is a type of micro-pattern gaseous detector currently under R&D for applications in rare event search experiments. Here we report the performance of a Micromegas structure constructed with a micromesh thermo-bonded to a readout plane, motivated by its potential application in two-phase xenon detectors for dark matter and neutrinoless double beta decay experiments. The study is carried out in pure xenon at room temperature. Measurements with alpha particles from the Americium-241 source showed that gas gains larger than 200 can be obtained at xenon pressure up to 3 atm. Gamma rays down to 8 keV were observed with such a device.

Wei, Yuehuan; Guan, Liang; Zhang, Zhiyong; Lin, Qing; Wang, Xiaolian; Ni, Kaixuan; Zhao, Tianchi

2013-08-01

33

Ternary gas mixture for diffuse discharge switch  

DOEpatents

A new diffuse discharge gas switch wherein a mixture of gases is used to take advantage of desirable properties of the respective gases. There is a conducting gas, an insulating gas, and a third gas that has low ionization energy resulting in a net increase in the number of electrons available to produce a current.

Christophorou, Loucas G. (Oak Ridge, TN); Hunter, Scott R. (Oak Ridge, TN)

1988-01-01

34

Dielectric gas mixtures containing sulfur hexafluoride  

DOEpatents

Electrically insulating gaseous media of unexpectedly high dielectric strength comprised of mixtures of two or more dielectric gases are disclosed wherein the dielectric strength of at least one gas in each mixture increases at less than a linear rate with increasing pressure and the mixture gases are present in such proportions that the sum of their electrical discharge voltages at their respective partial pressures exceeds the electrical discharge voltage of each individual gas at the same temperature and pressure as that of the mixture.

Cooke, Chathan M. (Cambridge, MA)

1979-01-01

35

Structural Plasticity of the Phage P22 Tail Needle gp26 Probed with Xenon Gas  

SciTech Connect

The tail needle, gp26, is a highly stable homo-trimeric fiber found in the tail apparatus of bacteriophage P22. In the mature virion, gp26 is responsible for plugging the DNA exit channel, and likely plays an important role in penetrating the host cell envelope. In this article, we have determined the 1.98 A resolution crystal structure of gp26 bound to xenon gas. The structure led us to identify a calcium and a chloride ion intimately bound at the interior of alpha-helical core, as well as seven small cavities occupied by xenon atoms. The two ions engage in buried polar interactions with gp26 side chains that provide specificity and register to gp26 helical core, thus enhancing its stability. Conversely, the distribution of xenon accessible cavities correlates well with the flexibility of the fiber observed in solution and in the crystal structure. We suggest that small internal cavities in gp26 between the helical core and the C-terminal tip allow for flexible swinging of the latter, without affecting the overall stability of the protein. The C-terminal tip may be important in scanning the bacterial surface in search of a cell-envelope penetration site, or for recognition of a yet unidentified receptor on the surface of the host.

Olia, A.; Casjens, S; Cingolani, G

2009-01-01

36

Structural plasticity of the phage P22 tail needle gp26 probed with xenon gas  

PubMed Central

The tail needle, gp26, is a highly stable homo-trimeric fiber found in the tail apparatus of bacteriophage P22. In the mature virion, gp26 is responsible for plugging the DNA exit channel, and likely plays an important role in penetrating the host cell envelope. In this article, we have determined the 1.98 Å resolution crystal structure of gp26 bound to xenon gas. The structure led us to identify a calcium and a chloride ion intimately bound at the interior of ?-helical core, as well as seven small cavities occupied by xenon atoms. The two ions engage in buried polar interactions with gp26 side chains that provide specificity and register to gp26 helical core, thus enhancing its stability. Conversely, the distribution of xenon accessible cavities correlates well with the flexibility of the fiber observed in solution and in the crystal structure. We suggest that small internal cavities in gp26 between the helical core and the C-terminal tip allow for flexible swinging of the latter, without affecting the overall stability of the protein. The C-terminal tip may be important in scanning the bacterial surface in search of a cell-envelope penetration site, or for recognition of a yet unidentified receptor on the surface of the host.

Olia, Adam S; Casjens, Sherwood; Cingolani, Gino

2009-01-01

37

Skin blood flow from gas transport: helium xenon and laser Doppler compared  

SciTech Connect

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-03-01

38

Insulation characteristics of gas mixtures including perfluorocarbon gas  

Microsoft Academic Search

This paper describes discharge properties of N2 and CO2-based gas mixtures including a perfluorocarbon (PFC) gas such as CF4, C3F8 and c-C4F8 under non-uniform field. The mixture ratio between a base gas of N2 or CO2 and the additive PFC gas was fixed as 9:1; namely, 90%N2\\/10%PFC or 90%CO2\\/10%PFC gas mixture. The PFC gases have even smaller global warming potential

Masayuki Hikita; Shinya Ohtsuka; Shigemitsu Okabe; Shuhei Kaneko

2008-01-01

39

Absorption of Gas Phase Contaminant Mixtures.  

National Technical Information Service (NTIS)

This project seeks to study the effect of multiple gas-vapor mixtures on the activated carbon adsorption breakthrough time and pattern. Activated carbon cartridges used for respiratory protection are tested in most cases for a single component at relative...

C. Lungu

2004-01-01

40

Intercollisional interference effect in the light scattering spectrum of xenon gas  

SciTech Connect

The depolarized, interaction-induced light scattering spectrum of xenon gas at room temperature has been measured in the very low frequency region, by means of a high resolution, high contrast monochromator. In addition to the accurate determination of the bound dimers band, a positive contribution in excess of the calculated pair spectrum is observed at lower frequency. A density analysis of this intensity excess shows that we have measured, for the first time, the intercollisional interference effect long ago predicted by Lewis and Van Kranendonk [Phys. Rev. Lett. {bold 24}, 802 (1970)]. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Ulivi, L.; Meinander, N.; Barocchi, F. [Istituto di Elettronica Quantistica, CNR, Via Panciatichi 56/30, 50127 Firenze (Italy)]|[Abo Akademi, Institutionen foer fysik, Porthansgatan 3, SF-20500 Abo (Finland)]|[Dipartimento di Fisica, Universita di Firenze, and Istituto di Fisica della Materia, sezione di Firenze, L. E. Fermi 2, 50125 Firenze (Italy)

1995-10-23

41

The Narrow Pulse Approximation and Long Length Scale Determination in Xenon Gas Diffusion NMR Studies of Model Porous Media  

Microsoft Academic Search

We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient pulses in a PGSE experiment (breakdown of

R. W. Mair; P. N. Sen; M. D. Hürlimann; S. Patz; D. G. Cory; R. L. Walsworth

2002-01-01

42

NEXT: Neutrino Experiment with high pressure Xenon gas TPC  

NASA Astrophysics Data System (ADS)

The search of the neutrinoless double-? decay address the major Physics goals of revealing the nature of the neutrino and setting an absolute scale for its mass. The observation of a positive ??0? signal, the unique signature of Majorana neutrinos, would have deep consequences in particle physics and cosmology. Therefore, any claim of observing a positive signal shall require extremely robust evidences. NEXT is a new double-? experiment which aims at building a 100 kg high pressure Xe136 gas TPC, to be hosted in the Canfranc Underground Laboratory (LSC), in Spain. This paper address the novel design concept of NEXT TPC believed to provide a pathway for an optimized and robust double-? experiment.

Yahlali, Nadia; Ball, M.; Cárcel, S.; Díaz, J.; Gil, A.; Gómez Cadenas, J. J.; Martín-Albo, J.; Monrabal, F.; Serra, L.; Sorel, M.

2010-05-01

43

Separation and purification of xenon  

DOEpatents

Xenon is separated from a mixture of xenon and krypton by extractive distillation using carbon tetrafluoride as the partitioning agent. Krypton is flushed out of the distillation column with CF.sub.4 in the gaseous overhead stream while purified xenon is recovered from the liquid bottoms. The distillation is conducted at about atmospheric pressure or at subatmospheric pressure.

Schlea, deceased, Carl Solomon (LATE OF Aiken, SC)

1978-03-14

44

Improved gas mixtures for gas-filled radiation detectors  

DOEpatents

Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

Christophorou, L.G.; McCorkle, D.L.; Maxey, D.V.; Carter, J.G.

1980-03-28

45

Gas mixtures for gas-filled particle detectors  

DOEpatents

Improved binary and tertiary gas mixtures for gas-filled particle detectors are provided. The components are chosen on the basis of the principle that the first component is one gas or mixture of two gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a gas (Ar) having a very small cross section at and below aout 0.5 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electron field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Maxey, David V. (Knoxville, TN); Carter, James G. (Oak Ridge, TN)

1980-01-01

46

Gas mixtures for gas-filled radiation detectors  

DOEpatents

Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Maxey, David V. (Knoxville, TN); Carter, James G. (Knoxville, TN)

1982-01-05

47

Luminescence from the laser transition 5 d[3/2]1-6 p[3/2]1 of atomic xenon upon excitation of He-Ar-Xe mixture by a pulsed electron beam of short duration  

NASA Astrophysics Data System (ADS)

The spontaneous emission yield from the 5 d[3/2]1 ? 6 p[3/2]1 transition in atomic xenon with a wavelength of 2.03 ?m upon excitation of a He-Ar-Xe medium by an electron beam of short duration (˜3 ns) was measured as a function of time for a wide range of partial composition of the gas mixture. The obtained data are analyzed. The experimental data agree with the calculated total lifetime of the level 5 d[3/2]1 of XeI in He-Ar-Xe mixtures with different partial composition. It is shown that the lifetime of this level determined by quenching induced by heavy particles is not established immediately following beam injection, but rather with a certain time delay determined by recombination processes in plasma.

Denezhkin, I. A.; D'yachenko, P. P.

2013-02-01

48

Initiation of Detonation in Various Gas Mixtures.  

National Technical Information Service (NTIS)

For the transition of a flame to a detonation the initiation distance, X(o), and the initiation time, t(D), have been measured for various detonable gas mixtures, and from these two quantities the Oppenheim velocity, V(Opp) = X(D)/t(D) has been obtained. ...

D. Pawel H. Vasatko H. G. Wagner P. J. Van Tiggelen

1970-01-01

49

Mesoscale Backtracking by Means of Atmospheric Transport Modeling of Xenon Plumes Measured by Radionuclide Gas Stations  

NASA Astrophysics Data System (ADS)

The monitoring of atmospheric radioactive xenon concentration is performed for nuclear safety regulatory requirements. It is also planned to be used for the detection of hypothetical nuclear tests in the framework of the Comprehensive nuclear-Test-Ban Treaty (CTBT). In this context, the French Atomic Energy Commission designed a high sensitive and automated fieldable station, named SPALAX, to measure the activity concentrations of xenon isotopes in the atmosphere. SPALAX stations were set up in Western Europe and have been operated quite continuously for three years or more, detecting principally xenon-133 and more scarcely xenon-135, xenon-133m and xenon-131m. There are around 150 nuclear power plants in the European Union, research reactors, reprocessing plants, medical production and application facilities releasing radioactive xenon in normal or incidental operations. A numerical study was carried out aiming to explain the SPALAX measurements. The mesoscale Atmospheric Transport Modelling involves the MM5 suite (PSU- NCAR) to predict the wind fields on nested domains, and FLEXPART, a 3D Lagrangian particle dispersion code, used to simulate the backward transport of xenon plumes detected by the SPALAX. For every event of detection, at least one potential xenon source has a significant efficiency of emission. The identified likely sources are located quite close to the SPALAX stations (some tens of kilometres), or situated farther (a few hundreds of kilometres). A base line of some mBq per cubic meter in xenon-133 is generated by the nuclear power plants. Peaks of xenon-133 ranging from tens to hundreds of mBq per cubic meter originate from a radioisotope production facility. The calculated xenon source terms required to obtain the SPALAX measurements are discussed and seem consistent with realistic emissions from the xenon sources in Western Europe.

Armand, P. P.; Achim, P.; Taffary, T.

2006-12-01

50

Xenon and Helium Gas Transport in the CT-based Human Lung Geometry  

NASA Astrophysics Data System (ADS)

Stable Xenon (Xe) gas has been used as an imaging agent for decades in its radioactive form, is chemically inert, and has been used as a ventilation tracer in its non radioactive form during computerized tomography (CT) imaging. Magnetic resonance imaging using hyperpolarized Helium (He) gas has also emerged as a powerful tool to study regional lung structure and function. However, the present state of knowledge regarding intra-bronchial Xe and He transport properties is incomplete. As the use of these gases rapidly advances, it has become critically important to understand the nature of their transport properties and to, in the process, better understand regional distribution of respiratory gases. In this study, we applied a custom-developed Characteristic-Galerkin finite element method to study transport of Xe and He in the CT-based human lung geometry, especially emulating the washin and washout processes. The realistic lung model is obtained from multidetector-row CT (MDCT) scanning of supine human subjects with lungs held at TLC and FRC. The simulation results show that the Xe/He washin and washout are governed by either flow instability or stable stratification, depending upon the relative density of resident gas versus inspired gas.

Lin, Ching-Long; Hoffman, Eric

2005-11-01

51

Separation of gas mixtures by supported complexes  

SciTech Connect

The goal of this program is to determine the feasibility of solvent-dissolved coordination complexes for the separation of gas mixtures under bench-scale conditions. In particular, mixtures such as low-Btu gas are examined for CO and H/sub 2/ separation. Two complexes, Pd/sub 2/(dpm)/sub 2/Br/sub 2/ and Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, were examined in a bench-scale apparatus for the separation of binary (CO-N/sub 2/ or H/sub 2/-N/sub 2/) and quinary (H/sub 2/, CO, CO/sub 2/, CH/sub 4/, and N/sub 2/) mixtures. The separation of CO-N/sub 2/ was enhanced by the presence of the palladium complex in the 1,1,2-trichloroethane (TCE) solvent, especially at high gas and low liquid rates. The five-component gas mixture separation with the palladium complex in TCE provided quite unexpected results based on physical solubility and chemical coordination. The complex retained CO, while the solvent retained CO/sub 2/, CH/sub 4/, and N/sub 2/ to varying degrees. This allowed the hydrogen content to be enhanced due to its low solubility in TCE and inertness to the complex. Thus, a one-step, hydrogen separation can be achieved from gas mixtures with compositions similar to that of oxygen-blown coal gas. A preliminary economic evaluation of hydrogen separation was made for a system based on the palladium complex. The palladium system has a separation cost of 50 to 60 cents/MSCF with an assumed capital investment of $1.60/MSCF of annual capacity charged at 30% per year. This assumes a 3 to 4 year life for the complex. Starting with a 90% hydrogen feed, PSA separation costs are in the range of 30 to 50 cents/MSCF. The ruthenium complex was not as successful for hydrogen or carbon monoxide separation due to unfavorable kinetics. The palladium complex was found to strip hydrogen gas from H/sub 2/S. The complex could be regenerated with mild oxidants which removed the sulfur as SO/sub 2/. 24 refs., 26 figs., 10 tabs.

Nelson, D.A.; Lilga, M.A.; Hallen, R.T.; Lyke, S.E.

1986-08-01

52

Constancy of the Dynamic Viscosities of Ternary Gas Mixtures.  

National Technical Information Service (NTIS)

The dynamic viscosities of ternary gas mixtures oxygen-nitrogen-carbon dioxide and hydrogen-nitrogen-oxygen are investigated. Starting from Wilke's equation for the prediction of the viscosities of gas mixtures whose volumetric analysis is known, it is sh...

G. J. G. Raja S. Natarajan

1967-01-01

53

Effective collision cross section of xenon plasma debris in argon buffer gas  

NASA Astrophysics Data System (ADS)

Mitigation of fast debris and soft x-rays generated from laser-produced xenon plasmas were studied in an argon buffer gas in laser intensities of 109-1011 W cm-2 using a cryogenic drum target. Considerable mitigation of debris was confirmed by measurements of material sputtering. From the experimental results, an attenuation parameter of sputtering by the debris \\bar \\sigma _1 and an absorption cross section of soft x-rays at 13.5 nm ?2(13.5?nm) were derived to be 2.2 × 10-20 m2 and 1.8 × 10-22 m2, respectively. Moreover, \\bar \\sigma _1 is concluded to be equivalent to the effective collision cross section ?1 of a debris particle at kinetic energy of 1-4 keV. Sufficient debris mitigation can be obtained together with low soft x-ray absorption (less than 10%). These parameters provide a useful design tool for realizing a practical soft x-ray source because they predict the effect of the buffer gas well.

Inoue, Tomoaki; Mochizuki, Takayasu; Masuda, Kazuya; Amano, Sho; Sekioka, Tsuguhisa; Kanda, Kazuhiro

2012-06-01

54

Investigation of the combined adsorption of krypton, xenon, and water vapor of the off-gas of atomic power stations  

Microsoft Academic Search

A radiochromatogra phic system of purifying the off-gas from the short-lived krypton, xenon, and iodine nuclides is presently used in Russian atomic power stations and in foreign atomic power stations equipped with the aid of the USSR. The basic elements of the system are filter-adsorbers filled with activated carbon and a drying unit [1-3]. Dynamic adsorption and radioactive decay in

I. E. Nakhutin; D. V. Ochkin; S. A. Tret'yak

1980-01-01

55

THEORETICAL STUDY ON THE INTERACTION BETWEEN XENON AND POSITIVE SILVER CLUSTERS IN GAS PHASE AND ON THE (001) CHABAZITE SURFACE  

SciTech Connect

A systematic study on the adsorption of xenon on silver clusters in the gas phase and on the (001) surface of silver-exchanged chabazite is reported. Density functional theory at the B3LYP level with the cluster model was employed. The results indicate that the dominant part of the binding is the {sigma} donation, which is the charge transfer from the 5p orbital of Xe to the 5s orbital of Ag and is not the previously suggested d{sub {pi}}-d{sub {pi}} back-donation. A correlation between the binding energy and the degree of {sigma} donation is found. Xenon was found to bind strongly to silver cluster cations and not to neutral ones. The binding strength decreases as the cluster size increases for both cases, clusters in the gas-phase and on the chabazite surface. The Ag{sup +} cation is the strongest binding site for xenon both in gas phase and on the chabazite surface with the binding energies of 73.9 and 14.5 kJ/mol, respectively. The results also suggest that the smaller silver clusters contribute to the negative chemical shifts observed in the {sup 129}Xe NMR spectra in experiments.

Hunter, D.

2009-03-16

56

Dynamics of neutral gas depletion investigated by time- and space-resolved measurements of xenon atom ground state density  

NASA Astrophysics Data System (ADS)

The dynamics of neutral gas depletion in high-density plasmas is investigated by time- and space-resolved measurements of the xenon ground state density. Two-photon absorbed laser induced fluorescence experiments were carried out in a helicon reactor operating at 10 mTorr in xenon gas. When the plasma is magnetized, a plasma column is formed from the bottom of the chamber up to the pumping region. In this situation it is found that two phenomena, with different time scales, are responsible for the neutral gas depletion. The magnetized plasma column is ignited in a short (millisecond) time scale leading to a neutral gas depletion at the discharge centre and to an increase of neutral gas density at the reactor walls. This is explained both by neutral gas heating and by the rise of the plasma pressure at the discharge centre. Then, on a much longer (second) time scale, the overall neutral gas density in the reactor decreases due to higher pumping efficiency when the magnetized plasma column is ignited. The pumping enhancement is not observed when the plasma is not magnetized, probably because in this case the dense plasma column vanishes and the plasma is more localized near the antenna.

Liard, L.; Aanesland, A.; Chabert, P.

2012-06-01

57

Automating component concentration measurement on test gas mixtures  

Microsoft Academic Search

Test gas mixtures TGM are used in testing and calibrating working gas analyzers. Gas mixtures GM are certified (the qualitative and quantitative compositions of the TGM are determined with a set accuracy) by means of standard means of measurement SMM and initial standard means of measurement ISMM. Both the latter types include semiautomatic and automatic gas analyzers in order to

Yu. A. Kustikov; E. A. Aksenov; O. B. Lipovskii; V. A. Novikov; G. F. Baidikov; Yu. S. Berner; I. A. Popazov

1985-01-01

58

Electron parameters in Xe-Ne mixtures  

Microsoft Academic Search

The effect made by xenon concentration and by reduced electric field on the parameters of electrons in Xe-Ne mixtures is numerically\\u000a studied. It is demonstrated that the increase in xenon concentration in mixture leads to a decrease in the average electron\\u000a energy, to an increase in the frequency of collisions of electrons with gas atoms, and to variation of the

S. V. Avtaeva

2010-01-01

59

Structural transition in mixed hydrates of xenon and krypton as a function of gas composition  

SciTech Connect

Six samples of mixed hydrates of structure I former Xe and structure II former Kr were prepared from gas mixtures in which the concentration of Xe varied from 1 to 24 mol %. The structures and compositions of the hydrates were studied by X-ray diffraction, NMR, and calorimetry. In all cases, there was significant enrichment of Xe in the hydrate phase. The structure of the mixed hydrate changed from structure II to structure I when the initial concentration of Xe in the gas mixture was 5 mol % or more. The results show that the structure of the mixed hydrate is primarily determined by the component having the larger Cf, where C is the Langmuir constant and f the partial fugacity.

Handa, Y.P.; Ratcliffe, C.I.; Ripmeester, J.A.; Tse, J.S. (National Research Council of Canada, Ottawa, Ontario (Canada))

1990-05-17

60

Compressed xenon gas near its critical point as an ionization medium  

SciTech Connect

As part of an effort to study Ov [beta][beta] decay of [sup 136]Xe, a compressed xenon drift chamber has been developed. In such a chamber, the ability to drift ionization over large distances without attenuation, stability with time, and excellent energy resolution are essential. Xenon is an attractive candidate for use as an ionization detection medium. Its low cost in large volumes gives it an advantage over solid-state detectors. Its large atomic number (Z = 54) and density (when compressed or condensed) give a high stopping power for [gamma]-radiation. The low average energy required to produce an electron-ion pair and small Fano factor allow good energy resolution. The expected intrinsic energy resolution is 2 and 4 keV FWHM at 1 MeV in liquid and gaseous xenon, respectively. Thus, high density xenon spectrometers have a detection efficiency similar to NaI(T1) crystals of the same size and an energy resolution comparable in theory to that in Ge(Li) detectors. However, the best energy resolution results in liquid xenon, 34 and 54 keV FWHM for the 570 and 1,064 keV photo-peaks of [sup 207]Bi, respectively, fall considerably short of the Fano factor predictions. It appears that the resolution is limited by some process other than Poisson fluctuations. In this report the authors describe results obtained from a dual gridded ionization chamber filled with highly purified gaseous xenon operating near its critical point where the density, [rho][sub c] = 1.09 g/cm[sup 3], approaches that of the liquid phase. This thermodynamic regime has not previously been studied in xenon.

Levin, C.; Markey, J. (Yale Univ., New Haven, CT (United States). A.W. Wright Nuclear Structure Lab.)

1993-08-01

61

Martian xenon components in Shergotty mineral separates: Locations, sources and trapping mechanisms  

NASA Astrophysics Data System (ADS)

Isotopic signatures and concentrations of xenon have been measured in Shergotty mineral separates by laser step heating. Martian atmosphere and 'martian interior' xenon are present, as is a spallation component. Martian atmospheric xenon is 5-10× more concentrated in opaque minerals (magnetite, ilmenite, and pyrrhotite) and maskelynite than in pyroxenes, perhaps reflecting grain size variation. This is shown to be consistent with shock incorporation. A component consisting of solar xenon with a fission contribution, similar to components previously identified in martian meteorites and associated with the martian interior, is best defined in the pyroxene-dominated separates. This component exhibits a consistent 129Xe (129Xe/132Xe ?1.2) excess over solar/planetary (129Xe/132Xe ?1.04). We suggest that gas present in the melt, perhaps a mixture of interior xenon and martian atmosphere, was incorporated into the pyroxenes in Shergotty as the minerals crystallized.

Ocker, K. D.; Gilmour, J. D.

2004-12-01

62

The noble gas xenon induces pharmacological preconditioning in the rat heart in vivo via induction of PKC-? and p38 MAPK  

PubMed Central

Xenon is an anesthetic with minimal hemodynamic side effects, making it an ideal agent for cardiocompromised patients. We investigated if xenon induces pharmacological preconditioning (PC) of the rat heart and elucidated the underlying molecular mechanisms. For infarct size measurements, anesthetized rats were subjected to 25?min of coronary artery occlusion followed by 120?min of reperfusion. Rats received either the anesthetic gas xenon, the volatile anesthetic isoflurane or as positive control ischemic preconditioning (IPC) during three 5-min periods before 25-min ischemia. Control animals remained untreated for 45?min. To investigate the involvement of protein kinase C (PKC) and p38 mitogen-activated protein kinase (MAPK), rats were pretreated with the PKC inhibitor calphostin C (0.1?mg?kg?1) or the p38 MAPK inhibitor SB203580 (1?mg?kg?1). Additional hearts were excised for Western blot and immunohistochemistry. Infarct size was reduced from 50.9±16.7% in controls to 28.1±10.3% in xenon, 28.6±9.9% in isoflurane and to 28.5±5.4% in IPC hearts. Both, calphostin C and SB203580, abolished the observed cardioprotection after xenon and isoflurane administration but not after IPC. Immunofluorescence staining and Western blot assay revealed an increased phosphorylation and translocation of PKC-? in xenon treated hearts. This effect could be blocked by calphostin C but not by SB203580. Moreover, the phosphorylation of p38 MAPK was induced by xenon and this effect was blocked by calphostin C. In summary, we demonstrate that xenon induces cardioprotection by PC and that activation of PKC-? and its downstream target p38 MAPK are central molecular mechanisms involved. Thus, the results of the present study may contribute to elucidate the beneficial cardioprotective effects of this anesthetic gas.

Weber, Nina C; Toma, Octavian; Wolter, Jessica I; Obal, Detlef; Mullenheim, Jost; Preckel, Benedikt; Schlack, Wolfgang

2004-01-01

63

Formation of Structured Water and Gas Hydrate by the Use of Xenon Gas in Vegetable Tissue  

NASA Astrophysics Data System (ADS)

Freezing is a valuable technique for food preservation. However, vegetables are known to be softening remarkably after freezing and thawing process. It is expected to find alternative technique instead of freezing. Recently, the application of structured water and/or gas hydrate had been attempted to prolong the preservation of vegetable. In this study, the formation process of structure water and/or gas hydrate in pure water and carrot tissue was investigated by using NMR relaxation times, T1 and T2, of which applying condition was up to 0.4MPa and 0.8MPa at 5oC. Under the pressure of 0.4MPa, no gas hydrate was appeared, however, at 0.8MPa, formation of gas hydrate was recognized in both water and carrot tissue. Once the gas hydrate formation process in carrot tissue started, T1 and T2 increased remarkably. After that, as the gas hydrate developed, then T1 and T2 turned to decrease. Since this phenomenon was not observed in pure water, it is suggested that behavior of NMR relaxation time just after the formation of gas hydrate in carrot tissue may be peculiar to compartment system such as inter and intracellular spaces.

Ando, Hiroko; Suzuki, Toru; Kawagoe, Yoshinori; Makino, Yoshio; Oshita, Seiichi

64

Cluster counting in helium based gas mixtures  

NASA Astrophysics Data System (ADS)

The statistical advantages deriving from counting primary ionization, as opposed to the conventional energy loss measurement, are extensively discussed. A primary ionization counting method is proposed for a ``traditional'', cylindrical, single sense wire cell drift chamber, which makes use of a helium based gas mixture. Its conceptual feasibility is proven by means of a simple Monte Carlo simulation. A counting algorithm is developed and tested on the simulation output. A definition of the parameters of the read-out and of the digitizing electronics is given, assuming the described counting algorithm applied to a general detector design, in order to have a complete and realistic planning of a cluster counting measurement. Finally, some interesting results from a beam test, performed according to the described parameters, on primary ionization measurements and on ?/? separation are shown.

Cataldi, G.; Grancagnolo, F.; Spagnolo, S.

1997-02-01

65

High-pressure Xenon Gas Electroluminescent TPC Concept for Simultaneous Searches for Neutrino-less Double Beta Decay & WIMP Dark Matter  

NASA Astrophysics Data System (ADS)

Xenon is an especially attractive candidate for both direct WIMP and 0- decay searches. Although the current trend has exploited the liquid phase, gas phase xenon offers some remarkable performance advantages for energy resolution, topology visualization, and discrimination between electron and nuclear recoils. The NEXT-100 experiment, now beginning construction in the Canfranc Underground Laboratory, Spain, will operate at 12 bars with 100 kg of ^136Xe for the 0- decay search. I will describe recent results with small prototypes, indicating that NEXT-100 can provide about 0.5% FWHM energy resolution at the decay 2457.83 keV Q-value, as well as rejection of -rays by topology. However, sensitivity goals for WIMP dark matter and 0- decay searches indicate the need for ton-scale active masses; NEXT-100 provides the springboard to reach this scale with xenon gas. I describe a scenario for performing both searches in a single high-pressure ton-scale xenon gas detector, without significant compromise to either. In addition, -- even in a single, ton-scale, high-pressure xenon gas TPC, an intrinsic sensitivity to the nuclear recoil direction may exist -- plausibly offering an advance of more than two orders of magnitude relative to current low-pressure TPC concepts. I argue that, in an era of deepening fiscal austerity, such a dual-purpose detector may be possible, at acceptable cost, within the time frame of interest, and deserves our collective attention.

Nygren, David

2013-04-01

66

The XENON100 Dark Matter Experiment  

SciTech Connect

The XENON Dark Matter Experiment aims at the direct detection of dark matter Weakly Interacting Massive Particles (WIMPs) with dual phase (liquid/gas) xenon time projection chambers (XeTPCs). Following the successful performance of the XENON10 detector, which has shown in 2007 the best sensitivity to spin-independent coupling of WIMPs to matter, we have designed and completed the construction of a new TPC with an active LXe shield, containing a total of 170 kg of xenon. The detector is currently undergoing final commissioning at the Gran Sasso Underground Laboratory. I will review the XENON10 results and present the status of the XENON100 experiment.

Aprile, Elena [Department of Physics, Columbia University, New York, NY 10027 (United States)

2009-04-17

67

Determination of pore sizes and volumes of porous materials by 129Xe NMR of xenon gas dissolved in a medium.  

PubMed

In our previous paper (J. Phys. Chem. B 2005, 109, 757) it was illustrated that the 129Xe NMR spectra of xenon dissolved in acetonitrile confined into mesoporous materials give detailed information on the system, especially about the pore sizes. A resonance signal originating from xenon atoms sited in very small cavities built up inside the pores during the freezing transition (referred to as signal D) turned out to be highly sensitive to the pore size. The emergence of this signal reveals the phase transition temperature of acetonitrile inside the pores, which can also be used to determine the size of the pores. In addition, the difference in the chemical shifts of two other signals arising from xenon dissolved in bulk and confined acetonitrile (B and C) provides another method for determining the pore sizes. In the present work, the observed correlations have been investigated using an extensive set of measurements with a variety of porous materials (silica gels and controlled pore glasses) with the mean pore diameters ranging from 43 to 2917 A. The usefulness of the correlations has been demonstrated by calculating the pore size distributions from the spectral data. The distributions are in agreement with those reported by the manufacturers, when the mean pore diameter is smaller than approximately 500 A. In addition, it has been shown that the porosity of the materials can be determined by comparing the intensities of the signals arising from the bulk and confined liquid. When acetonitrile is replaced by cyclohexane in the sample, the dependence of the chemical shift difference between the B and C signals on the pore size becomes more sensitive, but no D signal appears below the freezing point. In addition, the influence of xenon gas on the melting points of bulk and confined acetonitrile has been studied by 1H NMR cryoporometry. The measurements show that the temperature of the latter transition lowers slightly more, and consequently affects the pore sizes calculated by means of the difference in the phase transition temperatures. Hysteresis in the phase transitions in a cooling-warming cycle has also been studied as a function of the temperature stabilization time by 129Xe NMR of xenon dissolved in acetonitrile. PMID:16375434

Telkki, Ville-Veikko; Lounila, Juhani; Jokisaari, Jukka

2005-12-29

68

Noble Gas (Argon and Xenon)-Saturated Cold Storage Solutions Reduce Ischemia-Reperfusion Injury in a Rat Model of Renal Transplantation  

PubMed Central

Background Following kidney transplantation, ischemia-reperfusion injury contributes to adverse outcomes. The purpose of this study was to determine whether a cold-storage solution saturated with noble gas (xenon or argon) could limit ischemia-reperfusion injury following cold ischemia. Methods Sixty Wistar rats were randomly allocated to 4 experimental groups. Kidneys were harvested and then stored for 6 h before transplantation in cold-storage solution (Celsior®) saturated with either air, nitrogen, xenon or argon. A syngenic orthotopic transplantation was performed. Renal function was determined on days 7 and 14 after transplantation. Transplanted kidneys were removed on day 14 for histological and immunohistochemical analyses. Results Creatinine clearance was significantly higher and urinary albumin significantly lower in the argon and xenon groups than in the other groups at days 7 and 14. These effects were considerably more pronounced for argon than for xenon. In addition, kidneys stored with argon, and to a lesser extent those stored with xenon, displayed preserved renal architecture as well as higher CD-10 and little active caspase-3 expression compared to other groups. Conclusion Argon- or xenon-satured cold-storage solution preserved renal architecture and function following transplantation by reducing ischemia-reperfusion injury.

Irani, Y.; Pype, J.L.; Martin, A.R.; Chong, C.F.; Daniel, L.; Gaudart, J.; Ibrahim, Z.; Magalon, G.; Lemaire, M.; Hardwigsen, J.

2011-01-01

69

Procedure and apparatus for the optimization of reactive gas mixtures  

US Patent & Trademark Office Database

The invention relates to a procedure for determining the risk of flammability of a mixture of two reactive gases A, B, in an inert or base gas, which includes: a step of determining, in the flammability diagram for the A/B/base gas mixture, the change in the composition of the mixture in order to determine whether or not the composition has passed through the flammability region of the flammability diagram, when A is firstly injected into the inert or base gas to form a first mixture and then B is injected into the first mixture in order to form the final mixture; a step of comparing the mixing time, should the region have been passed through, with the chemical induction time for the mixture.

Bockel-Macal; Savine (Paris Cedex, FR); Illy; Fabien (Paris Cedex, FR); Avrillier; Pierre (Paris Cedex, FR)

2004-09-07

70

Removal of phosphine contaminant from carbon monoxide gas mixtures  

SciTech Connect

A method is claimed for removing small concentrations of phosphine contained in a carbon monoxide gas mixture by preferentially oxidizing the phosphine, in which the phosphine is oxidized with air at a temperature of from 500 to 800 to form phosphorus pentoxide, which is recovered from the gas mixture preferably as phosphoric acid.

Goldstein, D.; Munday, T.F.; Walden, J.

1980-01-22

71

Simultaneous magnetic resonance imaging of ventilation distribution and gas uptake in the human lung using hyperpolarized xenon-129  

PubMed Central

Despite a myriad of technical advances in medical imaging, as well as the growing need to address the global impact of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease, on health and quality of life, it remains challenging to obtain in vivo regional depiction and quantification of the most basic physiological functions of the lung—gas delivery to the airspaces and gas uptake by the lung parenchyma and blood—in a manner suitable for routine application in humans. We report a method based on MRI of hyperpolarized xenon-129 that permits simultaneous observation of the 3D distributions of ventilation (gas delivery) and gas uptake, as well as quantification of regional gas uptake based on the associated ventilation. Subjects with lung disease showed variations in gas uptake that differed from those in ventilation in many regions, suggesting that gas uptake as measured by this technique reflects such features as underlying pathological alterations of lung tissue or of local blood flow. Furthermore, the ratio of the signal associated with gas uptake to that associated with ventilation was substantially altered in subjects with lung disease compared with healthy subjects. This MRI-based method provides a way to quantify relationships among gas delivery, exchange, and transport, and appears to have significant potential to provide more insight into lung disease.

Mugler, John P.; Altes, Talissa A.; Ruset, Iulian C.; Dregely, Isabel M.; Mata, Jaime F.; Miller, G. Wilson; Ketel, Stephen; Ketel, Jeffrey; Hersman, F. William; Ruppert, Kai

2010-01-01

72

[Minimal-flow xenon and semiclosed circuit anesthesia for computed tomographic measurement of local cerebral blood flow (LCBF)].  

PubMed

For the purpose of decreasing the volume of expensive xenon, anesthesia with minimal-flow xenon and semiclosed circuit were induced for computed tomographic LCBF measurement. Eighteen patients with ischemic cerebral disease were studied. Anesthesia was induced with minimum dose of thiopental, diazepam and fentanyl. Muscle relaxation was obtained by means of pancuronium bromide. Patients were intubated and ventilated mechanically with flows of 6 l/min. O2 for 20 to 30 minutes to eliminate nitrogen from the system. O2 concentrations in semiclosed circuit were monitored throughout the procedures using galvanic battery. Endtidal CO2 tension was also measured for maintaining normocarbia. Blood gas analyses were carried out before xenon inhalation, during xenon inhalation and immediately before stopping inhalation of xenon-oxygen mixture. Xenon inhalation programs were subdivided into three groups, each of them consisted of 6 patients. The formula for calculating fresh gas flow for low flow semiclosed circuit was introduced according to Shimoji's which was based on the original formula of Foldes. O2 concentration in circuit was predicted to be 25%. Mean xenon uptake for initial 20 minutes was predicted to be 125 ml/min. or 360 ml/min. (Formula: see text) (CRO2: O2% in semiclosed circuit. FO2: fresh O2 flow ml/min. FXe: fresh xenon flow ml/min. VO2: oxygen consumption ml/min. VXe: mean xenon uptake ml/min.) The first group started xenon inhalation during pure xenon inflow into semiclosed circuit for two minutes and followed by about 68% xenon in O2 inhalation for 23 minutes. FXe and VXe were fixed at 700 ml/min and 360 ml/min respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6498027

Oku, S; Karasawa, J; Kuriyama, Y; Satou, K; Yahagi, N; Okumura, F; Kikuchi, H; Sawada, T; Sakashita, Z; Naitou, H

1984-08-01

73

Separation of gas mixtures by supported complexes  

SciTech Connect

A system was investigated that catalyzes the dehydrogenation of alcohols and the hydrogenation of ketones. Such a catalyst, if used in a membrane containing an alcohol solvent, might be of use in selective H/sub 2/ separation from gas mixtures. The dehydrogenation of cyclohexanol and 2-octanol were studied using a RhCl/sub 3//SnCl/sub 2//LiCl catalyst system. These alcohols are dehydrogenated at rates that are initially rapid, but which gradually slow to a stop. The decrease in rate of H/sub 2/ evolution is a result of the establishment of an equilibrium between the alcohol and the liberated hydrogen and ketone. At 150/sup 0/C, cyclohexanol has the fastest rate of dehydrogenation. Several dehydrogenation/hydrogenation cycles have been carried out using this alcohol over a period of one week without serious catalyst deactivation or side reactions. Initial tests of the catalyst dissolved in cyclohexanol within two membranes were inconclusive. An anion exchange membrane was not suitably wetted by the catalyst solution and Celgard/sup TM/, which was wetted, could not be kept wet at 150/sup 0/C under flow conditions in the membrane cell. 9 refs., 3 figs., 1 tab.

Nelson, D.A.; Lilga, M.A.

1986-12-01

74

Apparatus for the separation of gas mixtures, particularly the enrichment of a gas mixture in a component containing uranium 235  

Microsoft Academic Search

An apparatus for separating a gas mixture into a heavy component and a light component, especially for the enrichment of a gas mixture in uranium 235 in which the uranium isotopes are provided in the form of uranium hexafluoride, comprises a cascade of centrifuge stages each formed by a pair of spaced-apart disks surrounded by a housing and driven by

Gazda

1981-01-01

75

THE RECOVERY OF URANIUM FROM GAS MIXTURE  

DOEpatents

A method of separating uranium from a mixture of uranium hexafluoride and other gases is described that comprises bringing the mixture into contact with anhydrous calcium sulfate to preferentially absorb the uranium hexafluoride on the sulfate. The calcium sulfate is then leached with a selective solvent for the adsorbed uranium. (AEC)

Jury, S.H.

1964-03-17

76

An air-entrainment device for preparing precision gas mixtures.  

PubMed

Three low-cost venturi's built from readily available materials are described and evaluated to determine whether they can be used to prepare precision gas mixtures for the calibration of gas analysers. Using pure oxygen (O2) and nitrogen as the priming gases the venturi's generated mixtures with an O2 concentration within the range 12-53% O2. Over a two-week period, the variability was found to be less than 0.25% O2. The mixtures produced were found to vary according to the density of the priming gas, but were virtually independent of the priming flow rate. We conclude that the venturi may offer a simple and inexpensive method of preparing precision gas mixtures suitable for the calibration of gas analysers. PMID:6876135

Johns, D P; Streeton, J A; Rochford, P D

77

Optical pumping and xenon NMR  

SciTech Connect

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping {sup 129}Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the {sup 131}Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

Raftery, M.D.

1991-11-01

78

Optical pumping and xenon NMR  

SciTech Connect

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

Raftery, M.D.

1991-11-01

79

Negative muon capture in noble gas mixtures  

NASA Astrophysics Data System (ADS)

We have determined the probabilities of atomic negative muon capture in binary mixtures of the gases He, Ne, Ar, and Kr at partial pressures near five atmospheres. Relative capture rates were deduced from measured muonic X-ray yields.

Hutson, R. L.; Knight, J. D.; Leon, M.; Schillaci, M. E.; Knowles, H. B.; Reidy, J. J.

1980-03-01

80

Computer Analysis of the Mass Spectra of Gas Mixtures.  

National Technical Information Service (NTIS)

The report describes the development of a complex computer program package which can be used to solve the extremely difficult problem of analyzing gas mixtures, such as polymer pyralysis products, from their mass spectra. This program package can, using o...

R. H. Pritchard I. J. Goldfarb

1975-01-01

81

Velocity limitations in coaxial plasma gun experiments with gas mixtures  

Microsoft Academic Search

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

I. Axnaes

1976-01-01

82

Time-resolved spectral emission studies of a pulsed, high-pressure xenon gas discharge  

NASA Astrophysics Data System (ADS)

The physical processes taking place during a high-current discharge in a high-pressure xenon plasma were investigated, with the goal of enhancing the spectral match so as to improve the overall efficiency of solid-state lasers. The dominant mechanism for the production of optical emission from the high-current, high-pressure radiating xenon plasma is that of bound-bound transitions whose characteristic emission lines are broadened to the extent of at least ten angstroms by pressure (collision) broadening and Stark broadening processes. A limited degree of control over the shape of the broad emission spectrum can be exerted by a careful time-tailing of the discharge current pulse, and by proper choice of the flashtube voltage. However, an improved understanding of the time evolution of the plasma electron and ion temperatures and concentrations during the current pulse is necessary in order to more effectively control the optical emission spectrum of the flashtube through adjustment of the available electrical input parameters.

Figueroa, M.

83

Regional comparison of technetium-99m DTPA aerosol and radioactive gas ventilation (xenon and krypton) studies in patients with suspected pulmonary embolism  

SciTech Connect

The regional distribution of (99mTc)DTPA aerosol was compared with that of /sup 133/Xe (n = 30) and krypton (n = 24) in a group of patients with suspected pulmonary embolism. All patients had an aerosol study using a recently available commercial generator system, a ventilation study with one of the gases, and perfusion imaging. Regional information was assessed visually on xenon, krypton, and aerosol studies independently by considering each lung as three equal-sized zones. In addition, gas ventilation findings peripheral to regions of aerosol turbulence (hot spots) were evaluated. Only 64% of the zones were in complete agreement on xenon and aerosol. Most of the discordance between xenon and aerosol was accounted for by minor degrees of /sup 133/Xe washout retention in zones that appeared normal in the aerosol study. An agreement rate of 85% was noted between 81mKr and aerosol regionally. The regions of discordance between aerosol and gas studies, however, usually were associated with unimpressive perfusion defects that did not change the scintigraphic probability for pulmonary embolism in any patient. Regarding zones of aerosol hyperdeposition, 76% had associated washout abnormalities on xenon; however, there was no correlation between the presence of these abnormalities or perfusion abnormalities. The results confirm the high sensitivity of /sup 133/Xe washout imaging, but suggest that radioaerosol imaging will detect most parenchymal abnormalities associated with perfusion defects of significance.

Ramanna, L.; Alderson, P.O.; Waxman, A.D.; Berman, D.S.; Brachman, M.B.; Kroop, S.A.; Goldsmith, M.; Tanasescu, D.E.

1986-09-01

84

Dust\\/gas mixtures explosion regimes  

Microsoft Academic Search

The explosion features of nicotinic acid dust in atmosphere of methane and air at different concentrations of either dust or gaseous fuel are studied. Experimental measurements of the pressure history, deflagration index and flammability limits are performed by the standard 20l Siwek bomb though adapted for such hybrid mixtures.Data show non linear effect of explosion severity and the synergistic effects

A. Garcia-Agreda; A. Di Benedetto; P. Russo; E. Salzano; R. Sanchirico

2011-01-01

85

2D multinuclear NMR, hyperpolarized xenon and gas storage in organosilica nanochannels with crystalline order in the walls.  

PubMed

The combination of 2D 1H-13C and 1H-29Si solid state NMR, hyperpolarized 129Xe NMR, synchrotron X-ray diffraction, together with adsorption measurements of vapors and gases for environmental and energetic relevance, was used to investigate the structure and the properties of periodic mesoporous hybrid p-phenylenesilica endowed with crystalline order in the walls. The interplay of 1H, 13C, and 29Si in the 2D heteronuclear correlation NMR measurements, together with the application of Lee-Goldburg homonuclear decoupling, revealed the spatial relationships (<5 angstroms) among various spin-active nuclei of the framework. Indeed, the through-space correlations in the 2D experiments evidenced, for the first time, the interfaces of the matrix walls with guest molecules confined in the nanochannels. Organic-inorganic and organic-organic heterogeneous interfaces between the matrix and the guests were identified. The open-pore structure and the easy accessibility of the nanochannels to the gas phase have been demonstrated by highly sensitive hyperpolarized (HP) xenon NMR, under extreme xenon dilution. Two-dimensional exchange experiments showed the exchange time to be as short as 2 ms. Through variable-temperature HP 129Xe NMR experiments we were able to achieve an unprecedented description of the nanochannel space and surface, a physisorption energy of 13.9 kJ mol-1, and the chemical shift value of xenon probing the internal surfaces. These results prompted us to measure the high storage capacity of the matrix towards benzene, hexafluorobenzene, ethanol, and carbon dioxide. Both host-guest, CH...pi, and OH...pi interactions contribute to the stabilization of the aromatic guests (benzene and hexafluorobenzene) on the extended surfaces. The full carbon dioxide loading in the channels could be detected by synchrotron radiation X-ray diffraction experiments. The selective adsorption of carbon dioxide (ca. 90 wt %) vs that of oxygen and hydrogen, together with the permanent porosity, high thermal stability, and high degree of order, makes this a suitable matrix for purifying hydrogen in clean-energy generation. PMID:17579407

Comotti, Angiolina; Bracco, Silvia; Valsesia, Patrizia; Ferretti, Lisa; Sozzani, Piero

2007-06-19

86

Arc Thermal Recovery Speed in Different Gases and Gas Mixtures  

Microsoft Academic Search

One important requirement for circuit breakers when interrupting, short line fault currents is their ability to withstand the initial rise of the recovery voltage immediately after current zero. For gas flow breakers this capability is limited by the thermal recovery speed oI tne gas. The measured relative thermal recovery performance of various gases and their mixtures are reported. They differ

H. O. Noeske

1981-01-01

87

Electron drift velocities in mixtures of helium and xenon and experimental verification of corrections to Blanc's law  

SciTech Connect

Measurements of electron drift velocities were performed in pure Xe and He and in a number of mixtures ranging up to 70% of Xe. The data were obtained by using a pulsed Townsend technique over the density-normalized electric field strength E/N between 1 and 100 Td. Even for pure gases there are no data in the entire range covered here, and these data represent an extension of accurate drift velocities to higher E/N. A selection of well-established cross sections for low energies, which was extended to higher energies, led to a reasonably good agreement of the calculated transport coefficients with the available data. At the same time we have applied the standard (common E/N) Blanc's law and two forms of common mean energy (CME, due to Chiflykian) procedures. Blanc's law fails for most mixtures at low and moderate E/N, while the CME procedure is capable of following the experimental data for the mixtures much more closely, and even predicting the negative differential conductivity region when such effect does not exist for pure gases. Thus the present paper also represents an experimental test of procedures to correct the standard Blanc's law. Finally, we have used the data for two mixtures to obtain results for the third mixture and in all cases this procedure gave excellent results even though only the standard Blanc's law was used in the process.

Sasic, O.; Jovanovic, J.; Petrovic, Z. Lj.; Urquijo, J. de; Castrejon-Pita, J.R.; Hernandez-Avila, J.L.; Basurto, E. [Institute of Physics, P.O.B. 68, 11080 Zemun-Belgrade (Serbia and Montenegro); Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, P.O. Box 48-3, 62251, Cuernavaca Mor. (Mexico); Departamento de Energia, Universidad Autonoma Metropolitana, Av. San Pablo 180, 02200 Mexico, D.F. (Mexico); Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana, Av. San Pablo 180, 02200 Mexico, D.F. (Mexico)

2005-04-01

88

Chemical recognition of gases and gas mixtures with terahertz waves.  

PubMed

A time-domain chemical-recognition system for classifying gases and analyzing gas mixtures is presented. We analyze the free induction decay exhibited by gases excited by far-infrared (terahertz) pulses in the time domain, using digital signal-processing techniques. A simple geometric picture is used for the classif ication of the waveforms measured for unknown gas species. We demonstrate how the recognition system can be used to determine the partial pressures of an ammonia-water gas mixture. PMID:19881876

Jacobsen, R H; Mittleman, D M; Nuss, M C

1996-12-15

89

Xenon Diffusivity in Thoria-Urania Fuel  

SciTech Connect

Postirradiation annealing tests were performed to obtain the {sup 133}Xe diffusion coefficients in uranium dioxide (UO{sub 2}) and mixed thorium-uranium dioxide [(Th-U)O{sub 2}] fuels. Specimens were a single-grained UO{sub 2}, a polycrystalline UO{sub 2}, and a polycrystalline (Th-U)O{sub 2}. The (Th-U)O{sub 2} specimen was a mixture of 35% ThO{sub 2} and 65% UO{sub 2}. Each 300-mg specimen was irradiated to a burnup of 0.1 MWd/t U. Postirradiation annealing tests were performed at 1400, 1500, and 1600 deg. C, continuously. The xenon diffusion coefficients for the nearly stoichiometric single-grained UO{sub 2} agree well with the data of others. The xenon diffusion coefficients in the polycrystalline (Th-U)O{sub 2} are approximately one order lower than those in the polycrystalline UO{sub 2}. The xenon diffusion coefficient in the (Th-U)O{sub 2} increases with the increasing oxygen potential of the ambient gas.

Kim, Heemoon [Korea Atomic Energy Research Institute (Korea, Republic of); Park, Kwangheon [Kyunghee University (Korea, Republic of); Kim, Bong Goo [Korea Atomic Energy Research Institute (Korea, Republic of); Choo, Yong Sun [Korea Atomic Energy Research Institute (Korea, Republic of); Kim, Keon Sik [Korea Atomic Energy Research Institute (Korea, Republic of); Song, Kun Woo [Korea Atomic Energy Research Institute (Korea, Republic of); Hong, Kwon Pyo [Korea Atomic Energy Research Institute (Korea, Republic of); Kang, Young Hwan [Korea Atomic Energy Research Institute (Korea, Republic of); Ho, Kwangil [Suwon University (Korea, Republic of)

2004-07-15

90

Recovery of purified helium or hydrogen from gas mixtures  

DOEpatents

A process is described for the removal of helium or hydrogen from gaseous mixtures also containing contaminants. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatomspheric pressure to preferentially absorb the contaminants in the fluorocarbon. Unabsorbed gas enriched in hydrogen or helium is withdrawn from the absorption zone as product. Liquid fluorocarbon enriched in contaminants is withdrawn separately from the absorption zone. (10 claims)

Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

1974-01-15

91

Lattice Boltzmann model for thermal binary-mixture gas flows  

NASA Astrophysics Data System (ADS)

A lattice Boltzmann model for thermal gas mixtures is derived. The kinetic model is designed in a way that combines properties of two previous literature models, namely, (a) a single-component thermal model and (b) a multicomponent isothermal model. A comprehensive platform for the study of various practical systems involving multicomponent mixture flows with large temperature differences is constructed. The governing thermohydrodynamic equations include the mass, momentum, energy conservation equations, and the multicomponent diffusion equation. The present model is able to simulate mixtures with adjustable Prandtl and Schmidt numbers. Validation in several flow configurations with temperature and species concentration ratios up to nine is presented.

Kang, Jinfen; Prasianakis, Nikolaos I.; Mantzaras, John

2013-05-01

92

Lattice Boltzmann model for thermal binary-mixture gas flows.  

PubMed

A lattice Boltzmann model for thermal gas mixtures is derived. The kinetic model is designed in a way that combines properties of two previous literature models, namely, (a) a single-component thermal model and (b) a multicomponent isothermal model. A comprehensive platform for the study of various practical systems involving multicomponent mixture flows with large temperature differences is constructed. The governing thermohydrodynamic equations include the mass, momentum, energy conservation equations, and the multicomponent diffusion equation. The present model is able to simulate mixtures with adjustable Prandtl and Schmidt numbers. Validation in several flow configurations with temperature and species concentration ratios up to nine is presented. PMID:23767654

Kang, Jinfen; Prasianakis, Nikolaos I; Mantzaras, John

2013-05-21

93

METEORITIC KRYPTON AND BARIUM VERSUS THE GENERAL ISOTOPIC ANOMALIES IN METEORITIC XENON  

Microsoft Academic Search

General isotopic anomalies in meteoritic xenon are described in detail. ; Where superior isotopic analyses exist, the xenon anomalies appear to be the same ; for all meteorites. In other cases there is fair evidence that the xenon ; examined is a mixture of meteoritic and contaminating atmospheric xenon. Two ; superior krypton analyses for carbonaceous chondrites show no anomalies

D. Krummenacher; C. M. Merrihue; R. O. Pepin; J. H. Reynolds

1962-01-01

94

Equilibrium hydrate formation conditions for methylcyclohexane with methane and a ternary gas mixture  

Microsoft Academic Search

Equilibrium hydrate formation conditions for methane with methylcyclohexane (MCH), and a ternary gas mixture of methane, ethane, propane with methylcyclohexane are obtained by employing the isothermal pressure search method. Methylcyclohexane is reported to form structure H gas hydrates with a help gas. The equilibrium pressures of the ternary gas mixture–methycyclohexane system are higher than those of the ternary gas mixture

Zhi-Gao Sun; Shuan-Shi Fan; Kai-Hua Guo; Lei Shi; Ru-Zhu Wang

2002-01-01

95

Convergent Supersonic Gas Mixture Flow behind the Ring Slot Nozzle  

NASA Astrophysics Data System (ADS)

When the gas mixture with distinguished molecular masses flows in the field of macroscopic parameter gradients, the separation of gases occurs, accompanied in some conditions by strong energy transformation. We report the results of studying a new class of rarefied gas dynamic strongly non-equilibrium flows. The convergent supersonic flow of the gas mixture may result in the formation of relatively dense cloud of gas enriched by heavy component with the temperature elevated much higher than the stagnation temperature of the undisturbed flow. Such effects are the stronger the larger is the disparity of molecular masses. The conceptual idea of these phenomena is confirmed quantitatively by direct statistical simulation. In the particular case at some rarefaction for mixture 97.5%He+2.5%Xe the temperature in almost continuum clouds, isolated from the wall, has exceeded the stagnation temperature 1.5 times and more. We propose to use the discovered and studied gas dynamic schemes for fundamental researches of physicochemical properties in gases and for use in promising vacuum technologies. Special interest arises in the exploration and utilization of polyatomic gas energy transformation

Maltsev, R. V.; Rebrov, A. K.

2008-12-01

96

Flammability of gas mixtures. Part 2: influence of inert gases.  

PubMed

Ternary systems, which contain flammable gas, inert gas and air, were studied in order to give the user an evaluation of the ISO 10156 calculation method for the flammability of gas mixtures. While in Part 1 of this article the fire potential of flammable gases was the focal point, the influence of inert gases on the flammability of gas mixtures was studied in Part 2. The inerting capacity of an inert gas is expressed by the dimensionless K value, the so-called "coefficient of nitrogen equivalency". The experimental determination of K values is demonstrated by using explosion diagrams. The objective of this study was to compare the estimated results, given by ISO 10156, with measurements of explosion ranges based on the German standard DIN 51649-1, given by CERN and CHEMSAFE. The comparison shows that ISO 10156, Table 1, supplies conservative K values, which can be regarded as safe in all cases. Nevertheless, in a number of cases ISO underestimates the inerting capacity, so that non-flammable gas mixtures are considered flammable. PMID:15885405

Molnarne, Maria; Mizsey, Péter; Schröder, Volkmar

2005-05-20

97

SLW modeling of radiative transfer in multicomponent gas mixtures.  

NASA Astrophysics Data System (ADS)

The methods of spectral integration for SLW modeling in the multicomponent gas mixtures are considered. The direct method and the method of convolution are extended to the multicomponent mixtures. Two new methods of spectral integration are proposed: the method of superposition and the multiplication method. A hybrid method based on desirable attributes of the latter two methods is also considered. The validation of the methods is performed by the prediction of radiative transfer in isothermal homogeneous media and in a ternary gas mixture layer with step-wise variation of temperature and species concentrations (water vapor, carbon dioxide and carbon monoxide). The HITEMP spectral database is used for evaluation of SLW spectral parameters and line-by-line benchmark solution.

Solovjov, V. P.; Webb, B. W.

2000-05-01

98

Internal combustion engines fueled by natural gas—hydrogen mixtures  

Microsoft Academic Search

In this study, a survey of research papers on utilization of natural gas–hydrogen mixtures in internal combustion engines is carried out. In general, HC, CO2, and CO emissions decrease with increasing H2, but NOx emissions generally increase. If a catalytic converter is used, NOx emission values can be decreased to extremely low levels. Consequently, equivalence zero emission vehicles (EZEV) standards

S. Orhan Akansu; Zafer Dulger; Nafiz Kahraman; T. Nejat Veziro?lu

2004-01-01

99

Viscosity of Natural-Gas Mixtures: Measurements and Prediction  

Microsoft Academic Search

New measurements of the viscosity of a natural-gas mixture are reported. The measurements were performed in a vibrating-wire viscometer, in the temperature range from 313 to 455 K at a pressure close to atmospheric and in the temperature range from 240 to 353 K at pressures up to 15 MPa. The uncertainty of the reported measurements is estimated to be

M. J. Assael; N. K. Dalaouti; V. Vesovic

2001-01-01

100

Kinetic Theory of Reactive Gas Mixtures with Application to Combustion  

Microsoft Academic Search

We consider a generalized Boltzmann equation valid for dilute, isotropic, polyatomic gas mixtures with chemical reactions. Depending on the ratio of characteristic times between reactive and inert collisions, various chemical regimes are obtained in the first order Enskog expansion and their compatibility with the Boltzmann H-theorem is investigated. We then review the mathematical structure of the transport linear systems resulting

A. Ern; V. Giovangigli

2003-01-01

101

The Search for Dark Matter with the XENON100 Experiment  

SciTech Connect

The XENON Dark Matter Experiment aims at the direct detection of dark matter Weakly Interacting Massive Particles (WIMPs) with dual phase (liquid/gas) xenon time projection chambers (XeTPCs). Following the successful performance of the XENON10 detector, which has shown in 2007 the best sensitivity to spin-independent coupling of WIMPs to matter, we have designed and completed the construction of a new TPC with an active LXe shield, containing a total of 170 kg of xenon. The detector is currently undergoing final commissioning at the Gran Sasso Underground Laboratory. I will review the XENON10 results and present the status of the XENON100 experiment.

Aprile, Elena [Columbia University (United States)

2008-11-23

102

Quantification of Gas Mixtures with Active Recursive Estimation  

NASA Astrophysics Data System (ADS)

We present an active-sensing strategy to estimate the concentrations in a gas mixture using temperature modulation of metal-oxide (MOX) sensors. The approach is based on recursive Bayesian estimation and uses an information-theoretic criterion to select operating temperatures on-the-fly. Recursive estimation has been widely used in mobile robotics, e.g., for localization purposes. Here, we employ a similar approach to estimate the concentrations of the constituents in a gas mixture. In this formulation, we represent a concentration profile as a discrete state and maintain a `belief' distribution that represents the probability of each state. We employ a Bayes filter to update the belief distribution whenever new sensor measurements arrive, and a mutual-information criterion to select the next operating temperature. This allows us to optimize the temperature program in real time, as the sensor interacts with its environment. We validate our approach on a simulated dataset generated from temperature modulated responses of a MOX sensor exposed to a mixture of three analytes. The results presented here provide a preliminary proof of concept for an agile approach to quantifying gas mixtures.

Gosangi, Rakesh; Gutierrez-Osuna, Ricardo

2011-09-01

103

Measurement of xenon in uranium dioxide (UO 2) with SIMS  

Microsoft Academic Search

The detection of rare gases in irradiated nuclear fuel is a great challenge in nuclear industry. Although gas measurement is not usual using SIMS technique, we show that xenon can actually be measured in an implanted UO2 sample by SIMS. The physical mechanisms of xenon detection are discussed and a method is proposed for xenon quantitative measurement.

L. Desgranges; B. Pasquet

2004-01-01

104

[Analysis of benzodiazepine derivative mixture by gas-liquid chromatography].  

PubMed

The analysis of mixture of benzodiazepine derivates (chlordiazepoxide, flunitrazepam, medazepam, nitrazepam, oxazepam and tetrazepam) by gas--liquid chromatography (GLC) in purpose to separate and identify these psychotropic drugs in mixture is presented in this article. The experiment was carried out in vitro, accommodating this method for identification and separation of drugs, isolated from biological objects (blood and urine). Referring to data of annual reports of chemical investigations (1) above-mentioned psychotropic drugs are very frequent among drug intoxication. In most cases they are detected in the mixture of the same or different pharmacological group, and this causes difficulty for separation and identification. The analysis of the mixture was carried out by GLC, which is widely used in practice of forensic-chemical examination. Adsorbents and stationery phases were changed; the conditions and parameters of chromatography were modified, in purpose totally separate preparations in the mixture. For the separation and identification of all three preparation the column packed with Inerton Super with stationary phase 3% OV-17 is suitable. The column temperature-290 degrees C. The mixture of these drugs was excreted from body fluids (blood and urine) in vitro and investigated by GLC under these conditions. The results of investigation were similar. PMID:12474705

Zevzikovas, Andrejus; Kiliuviene, Guoda; Ivanauskas, Liudas; Dirse, Vidmantas

2002-01-01

105

Method for the simultaneous preparation of Radon-211, Xenon-125, Xenon-123, Astatine-211, Iodine-125 and Iodine-123  

DOEpatents

A method for simultaneously preparing Radon-211, Astatine-211, Xenon-125, Xenon-123, Iodine-125 and Iodine-123 in a process that includes irradiating a fertile metal material then using a one-step chemical procedure to collect a first mixture of about equal amounts of Radon-211 and Xenon-125, and a separate second mixture of about equal amounts of Iodine-123 and Astatine-211.

Mirzadeh, Saed (East Setauket, NY); Lambrecht, Richard M. (Quogue, NY)

1987-01-01

106

Gas adsorption and gas mixture separations using mixed-ligand MOF material  

DOEpatents

A method of separating a mixture of carbon dioxiode and hydrocarbon gas using a mixed-ligand, metal-organic framework (MOF) material having metal ions coordinated to carboxylate ligands and pyridyl ligands.

Hupp, Joseph T. (Northfield, IL); Mulfort, Karen L. (Chicago, IL); Snurr, Randall Q. (Evanston, IL); Bae, Youn-Sang (Evanston, IL)

2011-01-04

107

Separation of Gas Mixtures by Continuous Gas Hydrate Crystallization  

Microsoft Academic Search

The developing microelectronics needs progressively purer process gases. It is, therefore, necessary to devise new and improve the known purification methods. As a rule, a higher purification efficiency is achieved by complicating the process and implies a higher cost of the product. Therefore, the process flowsheet should be optimized in each particular case. Gas hydrate crystallization [1] is a promising

V. M. Vorotyntsev; V. M. Malyshev; P. G. Taraburov; G. M. Mochalov

2001-01-01

108

An automated interferometer for the analysis of anaesthetic gas mixtures.  

PubMed

A microprocessor-controlled interferometer is described. The eyepiece of a conventional Jamin type interferometer has been replaced by an array of photocells which records the intensity across the interference pattern. Mathematical correlation procedures are used to locate the principal interference pattern maximum and, by sequential analysis of a fresh gas mixture followed by fresh gas plus vapour, it is possible to determine both oxygen and vapour concentrations. The instrument was used to analyse mixtures of oxygen and nitrous oxide and also oxygen, nitrous oxide plus halothane. It was found that the oxygen concentration could be determined to an accuracy of +/- 1% v/v and the vapour concentration to +/- 0.1% v/v. The instrument is suitable for monitoring concentrations delivered by an anaesthetic machine and may be included in a microprocessor-controlled anaesthetic machine. PMID:3190975

Sugg, B R; Palayiwa, E; Davies, W L; Jackson, R; McGraghan, T; Shadbolt, P; Weller, S J; Hahn, C E

1988-10-01

109

Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

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

Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

2012-10-01

110

Predicting flammability of gas mixtures containing volatile organic compounds  

SciTech Connect

One requirement regarding the transportation of transuranic (TRU) radioactive waste containers currently limits the total concentration of potentially flammable volatile organic compounds (VOCs) and flammable gases in the headspace of the waste container. Typical VOCs observed in the drums include aromatic hydrocarbons, ketones, alcohols, cyclohexane, as well as chlorinated hydrocarbons (alkanes and alkenes). Flammable gases, such as hydrogen and methane, may be generated in the containers by radiation-induced decomposition (radiolysis) of water and hydrocarbon waste forms. An experimental program was initiated to identify an accurate means for predicting flammability for gas mixtures containing one or more of the following species: hydrogen, carbon tetrachloride, 1,2-dichloroethane, toluene, or 2-butanone. The lower flammability limits (LFL) of gas mixtures containing equimolar quantity for each species were determined in a 19-liter laboratory flammability chamber using a strong spark ignition source. The group factor contribution method was determined to be more accurate than the LeChatelier method for estimating the LFL for these gas mixtures.

Liekhus, K. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Zlochower, I. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States). Pittsburgh Research Lab.; Djordjevic, S.; Loehr, C. [Benchmark Environmental, Albuquerque, NM (United States)

1997-12-31

111

Solid Xenon Project  

SciTech Connect

Crystals like Germanium and Silicon need to be grown in specialized facilities which is time and money costly. It takes many runs to test the detector once it's manufactured and mishaps are very probable. It is of a great challenge to grow big germanium crystals and that's why stacking them up in a tower is the only way at the moment to increase testing mass. Liquid Noble gas experiments experiencing contamination problems, their predicted energy resolution at 10 keV and lower energy range is not as good as predicted. Every experiment is targeting one specific purpose, looking for one thing. Why not to design an experiment that is diverse and build a detector that can search for Dark Matter, Solar Axions, Neutrinoless Double Beta decay, etc. Solid Xenon detector is such detector. We designed a simple Xenon crystal growing chamber that was put together at Fermi National Accelerator Laboratory. The first phase of this experiment was to demonstrate that a good, crack free Xenon crystal can be grown (regardless of many failed attempts by various groups) and our first goal, 1 kg crystal, was successful.

Balakishiyeva, Durdana N.; Saab, Tarek [University of Florida (United States); Mahapatra, Rupak [Texas A and M University (United States); Yoo, Jonghee [FNAL (United States)

2010-08-30

112

Effect of xenon binding to a hydrophobic cavity on the proton pumping cycle in bacteriorhodopsin.  

PubMed

To understand the functional role of apolar cavities in bacteriorhodopsin, a light-driven proton pump found in Halobacterium salinarum, we investigated the crystal structure in pressurized xenon or krypton. Diffraction data from the P622 crystal showed that one Xe or Kr atom binds to a preexisting hydrophobic cavity buried between helices C and D, located at the same depth from the membrane surface as Asp96, a key residue in the proton uptake pathway. The occupation fraction of Xe or Kr was calculated as approximately 0.32 at a pressure of 1 MPa. In the unphotolyzed state, the binding of Xe or Kr caused no large deformation of the cavity. However, the proton pumping cycle was greatly perturbed when an aqueous suspension of purple membrane was pressurized with xenon gas; that is, the decay of the M state was accelerated significantly (~5 times at full occupancy), while the decay of an equilibrium state of N and O was slightly decelerated. A similar but much smaller perturbation in the reaction kinetics was observed upon pressurization with krypton gas. In a glycerol/water mixture, xenon-induced acceleration of M decay became less significant in proportion to the water activity. Together with the structure of the xenon-bound protein, these observations suggest that xenon binding helps water molecules permeate into apolar cavities in the proton uptake pathway, thereby accelerating the water-mediated proton transfer from Asp96 to the Schiff base. PMID:18930734

Hayakawa, Naoki; Kasahara, Takashi; Hasegawa, Daisuke; Yoshimura, Keiko; Murakami, Midori; Kouyama, Tsutomu

2008-10-09

113

49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.  

Code of Federal Regulations, 2012 CFR

...false Charging of cylinders with a mixture of compressed gas and other material...305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any...

2012-10-01

114

49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.  

Code of Federal Regulations, 2011 CFR

...false Charging of cylinders with a mixture of compressed gas and other material...305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any...

2011-10-01

115

Air gas dynamic spraying of powder mixtures: Theory and application  

NASA Astrophysics Data System (ADS)

The radial injection gas dynamic spray (RIGDS) technology of powder coatings deposition was considered for this work. A coating was created by injecting powders with variable compositions into a supersonic air jet and depositing powder on the substrate. This study describes the preliminary analysis of an air gas dynamic spray method realized by a portable RIGDS apparatus with a radial injection of powder. Attention was given to shock compaction processes during the coating structure formation and examples of powder mixtures utilization in RIGDS. It was shown that the operational parameters of supersonic powder-gas jet have a significant influence on the coating's microstructure, thus defining the high performance of the coating. Compaction and bonding of particles were analyzed.

Maev, R. Gr.; Leshchynsky, V.

2006-06-01

116

Autoerotic accident by inhalation of propane-butane gas mixture.  

PubMed

We present a case of an accidental autoerotic death involving the inhalation of a propane-butane gas mixture, also known as LPG (liquefied petroleum gas). A 19-year-old male was found dead in supine position in his bed in a residential accommodation one day after he was last seen alive. On a personal computer at the end of the bed, a pornographic movie was still running. On his left shoulder, an empty rubber balloon and on the bedside 2 empty "Kisag-Gas" cartridges were found. Toxicologic investigations revealed an intoxication with propane and butane, together with a recent consumption of cannabis. This case report compares the toxicologic findings with other recently published cases, and the theories of the toxic effects are discussed. PMID:16304471

Jackowski, Christian; Römhild, Wolfgang; Aebi, Beat; Bernhard, Werner; Krause, Dieter; Dirnhofer, Richard

2005-12-01

117

Separation of light gas mixtures using SAPO-34 membranes  

SciTech Connect

Continuous SAPO-34 membranes were prepared on porous alumina tubular supports, and shown to be useful for light gas separations at low and high temperatures. Single-gas permeances of CO{sub 2}, N{sub 2} and CH{sub 4} decreased with increasing kinetic diameter. For the best membrane at 300 K, the He and H{sub 2} permeances were less than that of CO{sub 2}, because He, H{sub 2}, and CO{sub 2} were small compared to the SAPO-34 pore, and differences in the heat of adsorption determined the permeance order. The smaller component permeated the fastest in CO{sub 2}/CH{sub 4}, CO{sub 2}/N{sub 2}, N{sub 2}/CH{sub 4}, H{sub 2}/CH{sub 4} and H{sub 2}/N{sub 2} mixtures between 300 and 470 K. For H{sub 2}/CO{sub 2} mixtures, which were separated by competitive adsorption at room temperature, the larger component permeated faster below 400 K. The CO{sub 2}/CH{sub 4} selectivity at room temperature was 36 and decreased with temperature. The H{sub 2}/CH{sub 4} mixture selectivity was 8 and constant with temperature up to 480 K. Calcination, slow temperature cycles, and exposure to water vapor had no permanent effect on membrane performance, but temperature changes of approximately 30 K/min decreased the membrane's effectiveness.

Poshusta, J.C.; Tuan, V.A.; Pape, E.A.; Noble, R.D.; Falconer, J.L.

2000-04-01

118

Xenon spill distribution and room clearance.  

PubMed

The purpose of these studies was to investigate actual xenon gas clearance times under different exhaust conditions, to compare them with the calculated clearance times, to observe the distribution of the xenon gas while it was being exhausted from the room, and to determine the cause of a stationary xenon cloud that appeared on some clinical images. Clearance times with and without a flexible exhaust hose placed next to a simulated 133Xe gas spill were compared with clearance times measured in a room with all exhaust closed off. Two gamma cameras were used to observe the transport and exhaust of xenon following a simulated spill. Clearance times with the flexible exhaust hose were less than one minute because the xenon gas was removed before it had a chance to disperse into the room. Conventional room clearance calculations based on uniform mixing and measured exhaust rates yielded a clearance time of 22 min. The source of an artifactual stationary cloud image was discovered to be a small amount of xenon trapped between the collimator and camera face. A negative pressure and dedicated exhaust can be even more effective in exhausting spilled xenon from a room than air transfer calculations predict. The authors believe the flexible hose should always be used. PMID:10524516

Kelsey, C A; Telepak, R J

1999-11-01

119

Argon-Hydrogen Shielding Gas Mixtures for Activating Flux-Assisted Gas Tungsten Arc Welding  

Microsoft Academic Search

Using activating flux for gas tungsten arc welding (GTAW) to improve penetration capability is a well-established technique.\\u000a Argon is an inert gas and the one most widely used as a shielding gas for GTAW. For the most austenitic stainless steels,\\u000a pure argon does not provide adequate weld penetration. Argon–hydrogen mixtures give a more even heat input to the workpiece,\\u000a increasing

Her-Yueh Huang

2010-01-01

120

Binary and ternary gas mixtures for use in glow discharge closing switches  

DOEpatents

Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

Hunter, Scott R. (Oak Ridge, TN); Christophorou, Loucas G. (Oak Ridge, TN)

1990-01-01

121

Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures  

DOEpatents

A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

Aines, Roger D.; Bourcier, William L.; Viani, Brian

2013-01-29

122

Measurements of local mixture fraction of reacting mixture in swirl-stabilised natural gas-fuelled burners  

Microsoft Academic Search

Local, time-dependent measurements of mixture fraction of the reacting mixture were obtained in a swirl-stabilised natural\\u000a gas-fuelled, nominally non-premixed burner using the intensity of chemiluminescence from OH? and CH? radicals. The measurements quantified the mean, rms of fluctuations and probability density functions of local mixture fraction\\u000a at the stabilisation region of the flame. In addition, the probability of flame presence

M. Orain; Y. Hardalupas

123

A gain model for x-ray lasing at ~2.8 Å in an intense laser irradiated gas of xenon clusters  

NASA Astrophysics Data System (ADS)

A variety of experiments have been carried out (Borisov et al 2008 J. Phys. B: At. Mol. Opt. Phys. 41 105602) in which a gas of xenon clusters containing between 5 and 20 atoms/cluster (Schroeder et al 2001 J. Phys. B: At. Mol. Opt. Phys. 34 297) was irradiated with a ~230 fs pulse of 248 nm laser radiation focused to an intensity level of ~1.6 × 1019 W cm-2. In these experiments, a channel was formed as the laser beam self-focused. Amplified x-ray emissions at ~2.8 Å were observed along the direction of the channel with measured gain coefficients of between 27 and 104 cm-1 being cited. In this paper, a xenon gain model is assembled, built from FAC generated data (Gu 2008 Can. J. Phys. 86 675), which allows gains comparable in magnitude to be calculated under a set of restrictive assumptions about the laser beam-cluster dynamics. The model includes a detailed description of the ionization and excitation dynamics of the Ni- and Co-like ionization stages into which a description of hole state generation in Co-like xenon is made through the photoionization (or collisional ionization) of 2s and 2p electrons. Our calculations show that, under specialized initial conditions and sufficiently high pumping rates, gains larger than 50 cm-1 are achievable in one of the seven radiative decays of the Co-like hole states. The calculated gains are sensitive to the ion density, the risetime of the photoionization rates and the early time heating rate of the cluster plasma.

Petrova, Tz B.; Whitney, K. G.; Davis, J.

2010-01-01

124

The mechanism and kinetics of energy transfer processes in Xe-CCl4-M (M=CO, CO2) mixtures irradiated by xenon resonance light  

NASA Astrophysics Data System (ADS)

The mechanism and kinetics of energy transfer from the Xe(6s[3/2]1) resonance state to CO and CO2 molecules have been investigated by XeCl(B-X) (?max=308 nm) fluorescence intensity measurements at stationary conditions in Xe-CCl4-M systems. Steady-state analysis of the fluorescence intensity dependence on the xenon and M pressure at constant CCl4 concentration shows that these processes occur in two- and three-body reactions: Xe(6s[3/2]10)+M-->products Xe(6s[3/2]10)+M+Xe-->products. The two-body rate constants for above reactions have been found to be (0.7+/-0.2)x10-10 and (4.9+/-0.4)x10-10 cm3 s-1 for CO and CO2, respectively. The three-body rate constants have been found to be (3+/-1)x10-29 and (2.4+/-0.3)x10-28 cm6 s-1 for CO and CO2, respectively. It has been shown that the third order reaction is a very effective channel of xenon excited atoms decay at high xenon pressures (P50 Torr).

Wojciechowski, K.

1999-01-01

125

An Analysis of Shock Waves in Binary Gas Mixtures with Special Regard to Temperature Overshoot.  

National Technical Information Service (NTIS)

Shock wave structures in argon-helium mixtures are numerically analysed on the basis of a kinetic model for binary gas mixtures. The results are compared with Harnett and Muntz' experiment, and reasonable agreement between computation and experiment is fo...

K. Abe H. Oguchi

1974-01-01

126

On studies of 3He and isobutane mixture as neutron proportional counter gas  

NASA Astrophysics Data System (ADS)

The performance of neutron detectors filled with 3He+iC4H10 (isobutane) gas mixtures has been studied and compared with the performance of detectors filled with 3He+Kr gas mixtures. The investigations are made to determine suitable concentration of isobutane in the gas mixture to design neutron proportional counters and linear position sensitive neutron detectors (1-D PSDs). Energy resolution, range of proportionality, plateau and gas gain characteristics are studied for various gas mixtures of 3He and isobutane. The values for various gas constants are determined by fitting the gas gains to Diethorn and Bateman's equations and their variation with isobutane concentration in the fill gas mixture is studied.

Desai, S. S.; Shaikh, A. M.

2006-02-01

127

Axial gas transports in DC-discharges in mixtures of gases  

Microsoft Academic Search

Selective transports in DC-discharges in gas mixtures cause a cataphoretic segregation of the gas mixture. The two transports treated are: 1) the ion transport and 2) the transport due to the momentum transfer of the electrons and ions to the gas. A stationary state will occur as a result of the counteracting diffusion transport. The density distribution of the gases

J. Freudenthal

1967-01-01

128

Surface Area Measurements Using Polarized Xenon NMR  

NASA Astrophysics Data System (ADS)

We developed a new NMR technique to measure the surface area of xenon-soluble porous media such as compacted polyethylene granulates (used in filtering, wicking, etc.), packs of polymeric beads (used for molecular fractionation, including radio-immunoassay), and lung tissue. The large chemical shift of the 129Xe NMR frequency enables independent observation and manipulation of both the dissolved and gas phase xenon resonances. The measured short-time rate of xenon interphase exchange depends on the surface area of the interface between the dissolved and gas phases. The porosity and surface area of four porous polymer solids were measured with xenon interphase exchange NMR, in good agreement with independent measurements obtained by confocal microscopy.

Mair, R. W.; Hoffmann, D.; Walsworth, R. L.; Butler, J. P.; Patz, S.; Topulos, G. P.

2000-06-01

129

Multicomponent gas mixture air bearing modeling via lattice Boltzmann method  

NASA Astrophysics Data System (ADS)

As the demand for ultrahigh recording density increases, development of an integrated head disk interface (HDI) modeling tool, which considers the air bearing and lubricant film morphology simultaneously is of paramount importance. To overcome the shortcomings of the existing models based on the modified Reynolds equation (MRE), the lattice Boltzmann method (LBM) is a natural choice in modeling high Knudsen number (Kn) flows owing to its advantages over conventional methods. The transient and parallel nature makes this LBM an attractive tool for the next generation air bearing design. Although LBM has been successfully applied to single component systems, a multicomponent system analysis has been thwarted because of the complexity in coupling the terms for each component. Previous studies have shown good results in modeling immiscible component mixtures by use of an interparticle potential. In this paper, we extend our LBM model to predict the flow rate of high Kn pressure-driven flows in multicomponent gas mixture air bearings, such as the air-helium system. For accurate modeling of slip conditions near the wall, we adopt our LBM scheme with spatially dependent relaxation times for air bearings in HDIs. To verify the accuracy of our code, we tested our scheme via simple two-dimensional benchmark flows. In the pressure-driven flow of an air-helium mixture, we found that the simple linear combination of pure helium and pure air flow rates, based on helium and air mole fraction, gives considerable error when compared to our LBM calculation. Hybridization with the existing MRE database can be adopted with the procedure reported here to develop the state-of-the-art slider design software.

Tae Kim, Woo; Kim, Dehee; Hari Vemuri, Sesha; Kang, Soo-Choon; Seung Chung, Pil; Jhon, Myung S.

2011-04-01

130

Fermion-fermion interaction in a dilute gas-mixture Bose condensate  

SciTech Connect

A mixture of a one-component Bose gas and two-component Fermi gas is considered at temperatures at which the Bose gas is completely condensed. Two fermions in such a mixture can interact with each other exchanging bosons from the condensate or supercondensate. The interaction potential, a change in the effective mass, the decay, and fermion spectrum are calculated in this quantum Fermi-Bose mixture.

Mogilyuk, T. I., E-mail: 5taras@mail.ru [National Research Centre Kurchatov Institute (Russian Federation)

2011-11-15

131

Effect of xenon on endotracheal tube cuff  

Microsoft Academic Search

Study Design:To investigate the effect of xenon on the endotracheal tube cuff in comparison to that of nitrous oxide.Design:Prospective, randomized study.Setting:Laboratory in vitro testing of endotracheal tubes.Interventions:Exposure of air-filled endotracheal tube cuffs to xenon or nitrous oxide (79 vol%) mixed with a balance of oxygen (21 vol%) for 3 hours.Measurements:The intra-cuff pressure and gas volume in the cuff were measured

Yoshiki Ishiguro; Hayato Saito; Yoshinori Nakata; Takahisa Goto; Katsuo Terui; Yoshinari Niimi; Shigeho Morita

2000-01-01

132

10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.  

Code of Federal Regulations, 2013 CFR

...against excessive use of petroleum or natural gas in mixtures-electing powerplants...against excessive use of petroleum or natural gas in mixturesâelecting powerplants...to use a mixture of petroleum or natural gas and an alternate fuel as...

2013-01-01

133

Gas Mixtures and Electrode Materials for Electroluminescence Detectors of Charged Particles.  

National Technical Information Service (NTIS)

The different gas mixtures (Ne, He, Ar, Xe and N sub 2 with acetone, benzene, athanol, methanol and toluene admixtures) and electrode materials (alluminium, copper, permalloy and carbon) for electroluminescent gas counter with plane-parallel electrodes ar...

S. V. Golovkin

1979-01-01

134

Pathway to cryogen free production of hyperpolarized Krypton-83 and Xenon-129.  

PubMed

Hyperpolarized (hp) (129)Xe and hp (83)Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp (129)Xe MRI cumbersome. For hp (83)Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For (129)Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized (129)Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm(3)/min. For hp (83)Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm(3)/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D(1) transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

Six, Joseph S; Hughes-Riley, Theodore; Stupic, Karl F; Pavlovskaya, Galina E; Meersmann, Thomas

2012-11-27

135

Fuel and control assembly tag gas  

SciTech Connect

This standard establishes the requirements for tag gas to be used for locating failed fuel pins and control rod absorber pins in the reactor by the failure monitoring system. Tag gas shall consist of varying isotopic mixtures of xenon, krypton, or other gases as specified in the Ordering Data.

Not Available

1986-01-01

136

Hyperpolarized xenon magnetic resonance of the lung and the brain  

NASA Astrophysics Data System (ADS)

Hyperpolarized noble gas Magnetic Resonance Imaging (MRI) is a new diagnostic modality that has been used successfully for lung imaging. Xenon is soluble in blood and inhaled xenon is transported to the brain via circulating blood. Xenon also accumulates in the lipid rich white matter of the brain. Hyperpolarized xenon can hence be used as a tissue- sensitive probe of brain function. The goals of this study were to identify the NMR resonances of xenon in the rat brain and evaluate the role of hyperpolarized xenon for brain MRI. We have developed systems to produce sufficient volumes of hyperpolarized xenon for in vivo brain experiments. The specialized instrumentation developed include an apparatus for optical pump-cell manufacture and high purity gas manifolds for filling cells. A hyperpolarized gas delivery system was designed to ventilate small animals with hyperpolarized xenon for transport to the brain. The T1 of xenon dissolved in blood indicates that the lifetime of xenon in the blood is sufficient for significant magnetization to be transferred to distal tissues. A variety of carrier agents for intravenous delivery of hyperpolarized xenon were tested for transport to distal tissues. Using our new gas delivery system, high SNR 129Xe images of rat lungs were obtained. Spectroscopy with hyperpolarized xenon indicated that xenon was transported from the lungs to the blood and tissues with intact magnetization. After preliminary studies that indicated the feasibility for in vivo rat brain studies, experiments were performed with adult rats and young rats with different stages of white matter development. Both in vivo and in vitro experiments showed the prominence of one peak from xenon in the rat brain, which was assigned to brain lipids. Cerebral brain perfusion was calculated from the wash-out of the hyperpolarized xenon signal in the brain. An increase in brain perfusion during maturation was observed. These experiments showed that hyperpolarized xenon MRI can be used to develop unique approaches to studying white matter and gray matter in the brain. Some of the possible applications of hyperpolarized xenon MRI in the brain are clinical diagnosis of white matter diseases, functional MRI (fMRI) and measurement of cerebral blood perfusion.

Venkatesh, Arvind Krishnamachari

2001-04-01

137

The Enriched Xenon Observatory  

SciTech Connect

The Enriched Xenon Observatory (EXO) experiment will search for neutrinoless double beta decay of {sup 136}Xe. The EXO Collaboration is actively pursuing both liquid-phase and gas-phase Xe detector technologies with scalability to the ton-scale. The search for neutrinoless double beta decay of {sup 136}Xe is especially attractive because of the possibility of tagging the resulting Ba daughter ion, eliminating all sources of background other than the two neutrino decay mode. EXO-200, the first phase of the project, is a liquid Xe time projection chamber with 200 kg of Xe enriched to 80% in {sup 136}Xe. EXO-200, which does not include Ba-tagging, will begin taking data in 2009, with two-year sensitivity to the half-life for neutrinoless double beta decay of 6.4x10{sup 25} years. This corresponds to an effective Majorana neutrino mass of 0.13 to 0.19 eV.

Dolinski, M. J. [Stanford University Physics Department, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)

2009-12-17

138

The Enriched Xenon Observatory  

NASA Astrophysics Data System (ADS)

The Enriched Xenon Observatory (EXO) experiment will search for neutrinoless double beta decay of 136Xe. The EXO Collaboration is actively pursuing both liquid-phase and gas-phase Xe detector technologies with scalability to the ton-scale. The search for neutrinoless double beta decay of 136Xe is especially attractive because of the possibility of tagging the resulting Ba daughter ion, eliminating all sources of background other than the two neutrino decay mode. EXO-200, the first phase of the project, is a liquid Xe time projection chamber with 200 kg of Xe enriched to 80% in 136Xe. EXO-200, which does not include Ba-tagging, will begin taking data in 2009, with two-year sensitivity to the half-life for neutrinoless double beta decay of 6.4×1025 years. This corresponds to an effective Majorana neutrino mass of 0.13 to 0.19 eV.

Dolinski, M. J.

2009-12-01

139

Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures  

SciTech Connect

Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed the avalanche process, and thus the avalanche process amplifies the REMPI signal. Possible applications are discussed.

Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B. [Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2008-07-15

140

Binary and ternary gas mixtures for use in glow discharge closing switches  

DOEpatents

Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

Hunter, S.R.; Christophorou, L.G.

1988-04-27

141

Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures  

DOEpatents

A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

Aines, Roger D.

2013-03-12

142

Process and apparatus for the treatment of moist gas-dust mixtures  

US Patent & Trademark Office Database

The invention relates to a process and an apparatus for the treatment of moist, explosive gas-dust mixtures, particularly coal dust mixtures in mill drying plants. To avoid a condensing out of residual moisture from intermediately stored dust, heated inert gas is supplied to the conveying system for the coal dust or the intermediate storage points.

1994-05-31

143

Diffusion of xenon (1); undecane (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) xenon; (2) undecane

Winkelmann, J.

144

High-field NMR of adsorbed xenon polarized by laser pumping  

Microsoft Academic Search

Optical pumping has been used to enhance the pulsed NMR signal of 129Xe, allowing the detecting of low-pressure xenon gas and of xenon adsorbed on powdered solids. We observe an increase in sensitivity of more than 2 orders of magnitude over conventional NMR, the current limitation being the laser power. Adsorbed xenon is observed at 298 K on graphitized carbon

D. Raftery; H. Long; T. Meersmann; P. J. Grandinetti; L. Reven; A. Pines

1991-01-01

145

Mass transfer of helium, neon, argon, and xenon through a steady-state upper mantle  

Microsoft Academic Search

We have examined the steady-state upper mantle model for helium, neon, argon, and xenon following the mass transfer approach presented by Kellogg and Wasserburg (1990) for helium and Porcelli and Wasserburg (1995a) for xenon. The model explains the available observational data of mantle helium, neon, argon, and xenon isotope compositions and provides specific predictions regarding the rare gas isotopic compositions

D. Porcelli; G. J. Wasserburg

1995-01-01

146

Laminar flame speeds of primary reference fuels and reformer gas mixtures  

Microsoft Academic Search

The laminar flame speeds of neat primary reference fuels (PRFs), n-heptane and iso-octane, PRF blends, reformer gas, and reformer gas\\/iso-octane\\/air mixtures are measured over a range of equivalence ratios at atmospheric pressure, using counterflow configuration and digital particle image velocimetry (DPIV). PRF blends with various octane numbers are studied. The synthetic reformer gas mixture employed herein has a composition that

Y. Huang; C. J. Sung; J. A. Eng

2004-01-01

147

Preparation of Calibration Gas Mixtures Using a Dynamic Volumetric Method for Environmental Monitoring  

Microsoft Academic Search

It is difficult to produce and maintain the quality of calibration gas mixtures stable and reliable in gas cylinders for the identification and quantification of trace environmental contaminants. Dynamic method has attracted an attention because immediate and on-site generation of calibration gas mixture is achievable in the range of percent, sub-ppm, and micro-mole fraction. The dynamic method for the preparation

S. Lee; W. Lee; S. Oh

2008-01-01

148

The XENON100 dark matter experiment  

NASA Astrophysics Data System (ADS)

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to search for xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper we present a detailed description of the detector design and present performance results, as established during the commissioning phase and during the first science runs.The active target of XENON100 contains 62 kg of LXe, surrounded by an LXe veto of 99 kg, both instrumented with photomultiplier tubes (PMTs) operating inside the liquid or in xenon gas. The LXe target and veto are contained in a low-radioactivity stainless steel vessel, embedded in a passive radiation shield and is installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. The experiment has recently published results from a 100 live-days dark matter search. The ultimate design goal of XENON100 is to achieve a spin-independent WIMP-nucleon scattering cross section sensitivity of ? = 2 × 10-45 cm2 for a 100 GeV/c2 WIMP.

Xenon100 Collaboration; Aprile, E.; Arisaka, K.; Arneodo, F.; Askin, A.; Baudis, L.; Behrens, A.; Brown, E.; Cardoso, J. M. R.; Choi, B.; Cline, D.; Fattori, S.; Ferella, A. D.; Giboni, K. L.; Kish, A.; Lam, C. W.; Lang, R. F.; Lim, K. E.; Lopes, J. A. M.; Marrodán Undagoitia, T.; Mei, Y.; Melgarejo Fernandez, A. J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Plante, G.; Ribeiro, A. C. C.; Santorelli, R.; Dos Santos, J. M. F.; Schumann, M.; Shagin, P.; Teymourian, A.; Tziaferi, E.; Wang, H.; Yamashita, M.

2012-04-01

149

Crystalline Xenon Particle Detector  

Microsoft Academic Search

The sensitivity necessary to measure single photon electrons may be achieved through ionization produced in a crystalline xenon based particle detector. Following crystal formation and the application of an electric field, the ionization drifts to the surface and can be extracted from the solid xenon. Quantification of the ions is accomplished by utilizing a silicon PIN diode scintillation detector with

J. A. Maxin; R. Blessitt; J. Gao; J. Miller; G. Salinas; J. Seifert; J. T. White

2004-01-01

150

Properties of steady discharge in Ar-Kr-F2 gas mixture  

SciTech Connect

Some properties of Ar-Kr-F/sub 2/ laser gas mixture plasma under steady discharge conditions are computed and discussed. Both the excitation rate of the discharging electrons and the distribution of the discharge energy are discussed. The effects of fluoride gas content and impurity gas content on the discharge property are studied.

Chengen, Z.

1981-11-01

151

The XENON Dark Matter Search  

Microsoft Academic Search

The XENON experiment will search for Weakly Interacting Massive Particles (WIMPS), a leading candidate for the dark matter content of the Universe. The XENON detector uses the simultaneous measurement of ionization and scintillation in liquid xenon to distinguish between nuclear recoils and background electronic interactions. Ionization electrons are extracted into the xenon vapor where they produce a large proportional scintillation

D. N. McKinsey

2006-01-01

152

GAS CHROMATOGRAPHIC RETENTION PARAMETERS DATABASE FOR REFRIGERANT MIXTURE COMPOSITION MANAGEMENT  

EPA Science Inventory

Composition management of mixed refrigerant systems is a challenging problem in the laboratory, manufacturing facilities, and large refrigeration machinery. Ths issue of composition management is especially critical for the maintenance of machinery that utilizes zeotropic mixture...

153

Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface.  

National Technical Information Service (NTIS)

Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distributio...

J. A. Ritter

1992-01-01

154

Hydrogen Content of Cooled Uranium Hexafluoride-Hydrogen Fluoride Gas Mixtures.  

National Technical Information Service (NTIS)

The knowledge of the hydrogen concentration of hydrogen fluoride (HF)/uranium hexafluoride (UF sub 6 ) gas mixtures when cooled below condensation or desublimation temperatures is necessary in determining fissile moderation for criticality safety consider...

W. D. Hedge C. M. Turner

1981-01-01

155

Application of azeotropic mixtures as standards in testing gas chromatographic systems and components  

Microsoft Academic Search

Summary  The use of specially chosen azeotropes is proposed as standards when testing gas chromatographs, detectors, columns and sample introduction systems. These azeotropic mixtures permit us to minimize the errors due to composition changes during sampling and sample introduction systems (intended for gases or liquids). The potentialities and advantages of such applications are illustrated using the azeotropic mixture of benzene and

B. V. Ioffe; A. G. Vitenberg; A. N. Marinichev; L. M. Kuznetsova

1976-01-01

156

Nonisothermal Adsorption: Separation of Gas Mixtures by Modulation of Feed Temperature  

Microsoft Academic Search

The purpose of this article was to present the principles and experimental examples of an adsorption process for separating gas mixtures characterized by the following features: the mixture to be treated contains a major component and a minor component, it is desired to produce a fraction of the pure major component and a fraction enriched in the minor component, the

Philippe Jacob; Daniel Tondeur

1980-01-01

157

Sympathetic cooling of an atomic Bose-Fermi gas mixture  

Microsoft Academic Search

Sympathetic cooling of an atomic Fermi gas by a Bose gas is studied by\\u000asolution of the coupled quantum Boltzmann equations for the confined gas\\u000amixture. Results for equilibrium temperatures and relaxation dynamics are\\u000apresented, and some simple models developed. Our study illustrate that a\\u000acombination of sympathetic and forced evaporative cooling enables the Fermi gas\\u000ato be cooled to

W. Geist; T. A. B. Kennedy

1999-01-01

158

Oxygen sensor for monitoring gas mixtures containing hydrocarbons  

DOEpatents

A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

Ruka, Roswell J. (Pittsburgh, PA); Basel, Richard A. (Pittsburgh, PA)

1996-01-01

159

Oxygen sensor for monitoring gas mixtures containing hydrocarbons  

DOEpatents

A gas sensor measures O{sub 2} content of a reformable monitored gas containing hydrocarbons, H{sub 2}O and/or CO{sub 2}, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system. 4 figs.

Ruka, R.J.; Basel, R.A.

1996-03-12

160

Method and apparatus for perforating at cutting with a solid fueled gas mixture  

SciTech Connect

A method for cutting pipe casings and concrete liners or perforating the same and localized portions of surrounding strata in an earth bore is set forth wherein a gas phase cutting or perforating jet mixture of fluorine and nitrogen trifluoride is delivered to the cutting or perforation site from the decomposition of a solid, normally stable, perfluoroammonium salt. An appropriate apparatus for delivering the gas mixture of fluorine and nitrogen trifluoride from the salt is also disclosed.

Woytek, A.J.; Lileck, J.T.; Steigerwalt, E.J.

1984-05-08

161

Hydrogen content of cooled uranium hexafluoride-hydrogen fluoride gas mixtures  

Microsoft Academic Search

The knowledge of the hydrogen concentration of hydrogen fluoride (HF)\\/uranium hexafluoride (UFâ) gas mixtures when cooled below condensation or desublimation temperatures is necessary in determining fissile moderation for criticality safety considerations in UFâ desublimation processes. The HF\\/UFâ gas mixtures used in this study were initially at 126°F (52°C) and a maximum of 607 torr before cooling to 60°F, 46°F, 32°F,

W. D. Hedge; C. M. Turner

1981-01-01

162

Electrochemical behaviour of a hydrogen\\/oxygen gas mixture at a solid polymer electrolyte interface  

Microsoft Academic Search

The electrochemical behaviour of a hydrogen\\/oxygen gas mixture at platinum electrodes in contact with a solid polymer electrolyte (Nafion 115) was studied in two modes: hydrogen enrichment and fuel cell. In the hydrogen enrichment (purification) mode, i\\/V(V being the applied voltage) characteristics were identified for the electrochemical cell arranged so that the gas mixture with varying ratios which contacts the

S. Y. Cha; J. M. Song; W. M. Lee

1998-01-01

163

Combustion characteristics of mixture of anode off gas and LNG in reformer  

Microsoft Academic Search

Fuel processing system which converts hydrocarbon fuel into hydrogen rich gas (by stream reforming, partial oxidation, auto-thermal reforming) needs high temperature environment (600–1000°C). Generally, anode off gas or mixture of anode off gas and LNG are used as input gas for a fuel reformer. In order to constitute efficient and low emission burner system for fuel reformer, it is necessary

Jae Young Lee; Pil Hyong Lee; Chang Soo Park; Bong Il Park; Sang Soon Hwang

2011-01-01

164

Microwave Determination of Water Mole Fraction in Humid Gas Mixtures  

NASA Astrophysics Data System (ADS)

A small volume (65 cm3) gold-plated quasi-spherical microwave resonator has been used to measure the water vapor mole fraction x w of H2O/N2 and H2O/air mixtures. This experimental technique exploits the high precision achievable in the determination of the cavity microwave resonance frequencies and is particularly sensitive to the presence of small concentrations of water vapor as a result of the high polarizability of this substance. The mixtures were prepared using the INRIM standard humidity generator for frost-point temperatures T fp in the range between 241 K and 270 K and a commercial two-pressure humidity generator operated at a dew-point temperature between 272 K and 291 K. The experimental measurements compare favorably with the calculated molar fractions of the mixture supplied by the humidity generators, showing a normalized error lower than 0.8.

Cuccaro, R.; Gavioso, R. M.; Benedetto, G.; Madonna Ripa, D.; Fernicola, V.; Guianvarc'h, C.

2012-09-01

165

Lung Surface Area Measurements Using Polarized Xenon NMR  

NASA Astrophysics Data System (ADS)

We are using laser-polarized xenon NMR to image the exchange of xenon from the lung gas space into solution in the alveolar tissue lining. The short-time rate of such xenon exchange depends on the surface area of the interface between the dissolved and gas phases. Hence xenon interphase exchange NMR will provide a non-invasive means to map the surface area of the lung. Since the function of the lung is to exchange gases between the bloodstream and the air, and the effectiveness of this gas exchange depends critically on the surface area of contact between blood-filled lung tissue and gas, our measurements will comprise imaging of lung function. This technique could be a powerful new tool for disease diagnosis and fundamental physiological research.

Hoffman, D.; Mair, R. W.; Walsworth, R. L.; Butler, J. P.; Patz, S.; Topulos, G. P.

1999-03-01

166

Prospects for Barium Tagging in Gaseous Xenon  

Microsoft Academic Search

Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the

D. Sinclair; E. Rollin; J. Smith; A. Mommers; N. Ackerman; B. Aharmim; M. Auger; P. S. Barbeau; C. Benitez-Medina; M. Breidenbach; A. Burenkov; S. Cook; A. Coppens; T. Daniels; R. DeVoe; A. Dobi; M. J. Dolinski; K. Donato; Fairbank W. Jr; J. Farine; G. Giroux

2012-01-01

167

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

PubMed

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

Wagatsuma, Kazuaki

2010-01-01

168

The Xenon record of Earth's early differentiaiton  

NASA Astrophysics Data System (ADS)

Xenon isotopes in mantle derived rocks provide information on the early differentiation of the silicate mantle of our planet. {131,132 134,136}Xe isotopes are produced by the spontaneous fission of two different elements: the now extinct radionuclide 244Pu, and the long-lived 238U. These two parent nuclides, however, yield rather different proportion of fissiogenic Xenon isotopes. Hence, the proportion of Pu- to U-derived fission xenon is indicative of the degree and rate of outgassing of a mantle reservoir. Recent data obtained from Iceland in our lab confirm that the Xenon isotopic composition of the plume source(s) is characterized by lower 136Xe/130Xe ratios than the MORB source and the Iceland plume is more enriched in the Pu-derived Xenon component. These features are interpreted as reflecting different degrees of outgassing and appear not to be the result of preferential recycling of Xenon to the deep mantle. To further investigate how representative the Icelandic measurements might be of other mantle plumes, we measured noble gases (He, Ne, Ar, Xe) in gas-rich basalt glasses from the Rochambeau Ridge (RR) in the Northern Lau Basin. Recent work suggests the presence of a "Samoan-like" OIB source in the northern Lau Basin and our measurements were performed on samples with plume-like 3He/4He ratios (15-28 RA) [1]. The Xenon isotopic measurements indicate that the maximum measured 136Xe/130Xe ratios in the Rochambeau samples are similar to Iceland. In particular, for one of the gas rich samples we were able to obtain 77 different isotopic measurements through step-crushing. Preliminary investigation of this sample suggests higher Pu- to U-derived fission Xenon than in MORBs. To quantitatively evaluate the degree and rate of outgassing of the plume and MORB reservoirs, particularly during the first few hundred million years of Earth's history, we have modified a geochemical reservoir model that was previously developed to investigate mantle overturn and mixing from He, Ar and lithophile isotopes [2]. We will present the results from this geochemical reservoirs model, which is constrained by our high precision dataset from the Rochambeau Rift (Northern Lau Basin) and Iceland along with the Xenon dataset from popping rock [3]. [1] Lupton et al., GRL, 2009. [2] Gonnermann and Mukhopadhyay, Nature, 2009. [3] Kunz et al., Science, 1998.

Peto, M. K.; Mukhopadhyay, S.; Kelley, K. A.

2011-12-01

169

A robot for weighing syringes used in reference gas mixture preparation  

NASA Astrophysics Data System (ADS)

In the preparation of some types of reference gas mixtures, one of the starting materials is a liquid. The liquid is introduced in the cylinder by means of a syringe. The weighing of these syringes before and after injection is critical for the calculation of the gas composition. A robot has been developed to facilitate this weighing of syringes used in the gravimetric preparation of these gas mixtures. From the validation work, it is clear that the robot performs the measurements more reliably and with better repeatability than the manual method. The percentage of non-conforming gas mixtures dropped from approximately 5% to less than 1%. Subsequent experiments to revisit assumptions made in the preparation process have gained new insight into effects such as convection and evaporation of liquid. Additional preventive measures are taken, to further improve the weighing accuracy, and by implication, the accuracy of the gas composition data calculated from preparation. The gain in uncertainty is different for various types of gas mixtures and depends largely on the thermophysical properties of the liquid and the gas mixture being prepared.

van Andel, I.; van der Veen, A. M. H.; Zalewska, E. T.

2012-08-01

170

HXeOBr in a xenon matrix  

SciTech Connect

We report on a new noble-gas molecule HXeOBr prepared in a low-temperature xenon matrix from the HBr and N{sub 2}O precursors by UV photolysis and thermal annealing. This molecule is assigned with the help of deuteration experiments and ab initio calculations including anharmonic methods. The H-Xe stretching frequency of HXeOBr is observed at 1634 cm{sup -1}, which is larger by 56 cm{sup -1} than the frequency of HXeOH identified previously. The experiments show a higher thermal stability of HXeOBr molecules in a xenon matrix compared to HXeOH.

Khriachtchev, Leonid; Tapio, Salla; Domanskaya, Alexandra V.; Raesaenen, Markku [Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 (Finland); Isokoski, Karoliina [Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Lundell, Jan [Department of Chemistry, University of Jyvaeskylae, P.O. Box 35, FIN-40014 Jyvaeskylae (Finland)

2011-03-28

171

Environmental Applications of Stable Xenon and Radioxenon Monitoring  

SciTech Connect

Improved detection capabilities are needed at several Department of Energy sites to make remedial decisions about facilities and landfill cleanup. For facility monitoring air samples can be collected from within a facility and analyzed for short lived radioxenons to estimate inventories of residual plutonium holdup within the facility. For landfill cleanup activities soil gas sampling for xenon isotopes can be used to define the locations of spent fuel and transuranic wastes. Short-lived radioxenon isotopes are continuously produced by spontaneous fission of plutonium-240 in transuranic wastes. Large volume soil-gas samples provide extremely sensitive measurement of radioxenon in the subsurface; a characteristic of transuranic waste. The analysis employs a modified Automated Radioxenon Sampling and Analysis (ARSA) system. Proof of principle measurements at a Hanford Site liquid waste disposal site showed xenon-133 at levels in soil gas are approximately 16,000 times the detection limit and lower levels of xenon-135 from the spontaneous fission of plutonium-240 were also measured. Stable xenon isotopes are also produced by spontaneous fission but are subject to background concentrations in ambient air samples (facilities) but less so in soil gas where free exchange with ambient air is restricted. Rare gas mass spectrometry is used for highly precise stable xenon isotopic measurements. Stable xenon isotopic ratios from fission are distinct from natural xenon background ratios. Neutron capture on xenon-135 produces an excess of xenon-136 above fission ratios and thus provides a means of distinguishing reactor sources (e.g. spent fuel) from separated transuranic materials (plutonium).

Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre, Justin I.; Waichler, Scott R.; Kennedy, B. M.

2008-06-01

172

Pressurised xenon as scintillator for gamma spectroscopy  

NASA Astrophysics Data System (ADS)

Detectors based on liquid or gas xenon have been used and are in use for a number of applications, in particular for the detection of gamma rays. Xenon is a well-suited medium for gamma spectroscopy thanks to its high atomic number and, consequently, large cross-section for photo-electric absorption. This paper presents experimental studies of high pressure xenon as a scintillator, with the aim of developing a gamma ray detector for the detection of Special Nuclear Materials (SNM). The first goal was to study the dependence of the light yield and of the energy resolution on the thermodynamic conditions. We present preliminary results from an optimised version of the detector.

Resnati, F.

2013-09-01

173

10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.  

Code of Federal Regulations, 2013 CFR

...against excessive use of petroleum or natural gas in mixtures-certifying powerplants...against excessive use of petroleum or natural gas in mixturesâcertifying powerplants...prohibit the use of petroleum or natural gas in such powerplant in...

2013-01-01

174

Gas Detonation Forming by a Mixture of H2+O2 Detonation  

Microsoft Academic Search

Explosive forming is one of the unconventional techniques in which, most commonly, the water is used as the pressure transmission medium. One of the newest methods in explosive forming is gas detonation forming which uses a normal shock wave derived of gas detonation, to form sheet metals. For this purpose a detonation is developed from the reaction of H2+O2 mixture

Morteza Khaleghi Meybodi; Hossein Bisadi

2009-01-01

175

Structure of normal shock waves in a gas-particle mixture  

NASA Astrophysics Data System (ADS)

The particle-volume effect is used to obtain the structure of a normal shock wave propagating in a gas particle mixture. It is found that particle temperature increases monotonically from its frozen value, with a trend similar to that obtained by Varma and Chopra (1967). Results are given for the variation of gas and particle velocity behind the shock wave.

Srivastava, R. S.; Sharma, J. P.

1982-11-01

176

Simulating thermo-mechanical interaction between a xenon gas-filled chamber and tungsten first-wall armor for the LIFE reactor design using the BUCKY 1-D radiation hydrodynamics code  

NASA Astrophysics Data System (ADS)

The BUCKY 1-D radiation hydrodynamics code has been used to simulate the dynamic thermo-mechanical interaction between a xenon gas-filled chamber and tungsten first-wall armor with an indirect-drive laser fusion target for the LIFE reactor design. Two classes of simulations were performed: (1) short-time (0-2 ms) simulations to fully capture the hydrodynamic effects of the introduction of the LIFE indirect-drive target x-ray and ion threat spectra and (2) long-time (2-70 ms) simulations starting with quiescent chamber conditions characteristic of those at 2 ms to estimate xenon plasma cooling between target implosions at 13 Hz. The short-time simulation results reported are: (1) the plasma hydrodynamics of the xenon in the chamber, (2) dynamic overpressure on the tungsten armor, and (3) time-dependent temperatures in the tungsten armor. The ramifications of local thermodynamic equilibrium (LTE) vs. non-LTE opacity models are also addressed.

Heltemes, T. A.; Prochaska, A. E.; Moses, G. A.

2010-08-01

177

Accuracy Improvement of a Concentration and Flow Measurement System for Binary Gas Mixtures  

NASA Astrophysics Data System (ADS)

This study intends to improve the accuracy of the concentration and flow measurement system for binary gas mixtures that was developed by two of the present authors1). This system is composed of a venturi tube and a laminar flowmeter connected in series. A basic examination on the viscosity estimate for binary gas mixtures and a preliminary measurement of the flow coefficient of the venturi tube are carried out. The procedure of concentration calculation based on the basic study is also shown. The estimate accuracy of the mole fractions of component gases and the flow rate of binary gas mixtures are experimentally examined using three kinds of mixed gas: CO2-Air, CO2-Ar and Ar-He. The results indicate that the mole fractions can be estimated with accuracy of 5% and the flow rate can be estimated with accuracy of 2%.

Youn, Chongho; Kogo, Akira; Kawashima, Kenji; Kagawa, Toshiharu

178

Xenon-neon gas proportional-scintillation counters for X rays below 2 keV: experimental results  

Microsoft Academic Search

The energy spectra of X-rays with energies below 2 keV measured with standard Xe filled gas proportional scintillation counters at atmospheric pressure exhibit a distorted tail towards the low energy region, due to the loss of electrons to the detector entrance window. In this framework, a Monte Carlo simulation study taking into account these losses has previously investigated the use

F. I. G. M. Borges; F. P. Santos; J. M. F. dos Santos; T. H. V. T. Dias; P. J. B. M. Rachinhas; C. A. N. Conde

2002-01-01

179

Hydrogen content of cooled uranium hexafluoride-hydrogen fluoride gas mixtures  

SciTech Connect

The knowledge of the hydrogen concentration of hydrogen fluoride (HF)/uranium hexafluoride (UF/sub 6/) gas mixtures when cooled below condensation or desublimation temperatures is necessary in determining fissile moderation for criticality safety considerations in UF/sub 6/ desublimation processes. The HF/UF/sub 6/ gas mixtures used in this study were initially at 126/sup 0/F (52/sup 0/C) and a maximum of 607 torr before cooling to 60/sup 0/F, 46/sup 0/F, 32/sup 0/F, 15/sup 0/F and 0/sup 0/F. Starting HF/UF/sub 6/ gas mixture volume ratios wre 10/90, 50/50, and 90/10. Visual evidence of liquid HF occurred only in the cooling of 90/10 mixtures at or below 32/sup 0/F. Maximum relative enhancement (factor of 3) of HF in the cooled mixture occurred at 15/sup 0/F from a 10/90 initial HF/UF/sub 6/ gas mixture.

Hedge, W.D.; Turner, C.M.

1981-03-01

180

Transport and recombination of electrons in a high pressure proportional counter using different gas mixtures  

NASA Astrophysics Data System (ADS)

Charge amplification and transport in a cylindrical proportional counter have been studied for a number of gas mixtures at high pressures, as a function of the distance of the primary interaction from the anode. We discuss various known theoretical gas gain formulae, the electron swarm characteristics and transport, and derive information on recombination rates as a function of gas pressure and reduced electric field using spectral analysis.

Manchanda, R. K.; Sood, R. K.; Grey, D. J.; Isbister, D. J.

2008-10-01

181

Laser cooling of dense rubidium-noble gas mixtures via collisional redistribution of radiation  

NASA Astrophysics Data System (ADS)

We describe experiments on the laser cooling of both helium-rubidium and argon-rubidium gas mixtures by collisional redistribution of radiation. Frequent alkali-noble gas collisions in the ultradense gas, with typically 200 bar of noble buffer gas pressure, shift a highly red detuned optical beam into resonance with a rubidium Dline transition, while spontaneous decay occurs close to the unshifted atomic resonance frequency. The technique allows for the laser cooling of macroscopic ensembles of gas atoms. The use of helium as a buffer gas leads to smaller temperature changes within the gas volume due to the high thermal conductivity of this buffer gas, as compared to the heavier argon noble gas, while the heat transfer within the cell is improved.

Vogl, Ulrich; Saß, Anne; Weitz, Martin

2012-02-01

182

Xenon-neon gas proportional-scintillation counters for X-rays below 2 keV: experimental results  

Microsoft Academic Search

The energy spectra of X-rays with energies below 2 keV measured with standard Xe filled gas proportional-scintillation counters at atmospheric pressure exhibit a distorted tail toward the low energy region, due to the loss of electrons to the detector entrance window. In this framework, a Monte Carlo simulation study taking into account these losses has previously investigated the use of

F. I. G. M. Borges; F. P. Santos; J. M. F. dos Santos; T. H. V. T. Dias; P. J. B. M. Rachinhas; C. A. N. Conde

2003-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

184

Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection  

DOEpatents

A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

Owen, Thomas E. (Helotes, TX); Miller, Michael A. (San Antonio, TX)

2010-08-24

185

Molecular Theory and Computer Simulation Studies of Natural and Synthetic Gas Mixtures. Final Report January 1, 1983-December 31, 1986.  

National Technical Information Service (NTIS)

Studies of bulk fluid mixtures and of liquid surface properties (liquid-gas and liquid-liquid) by statistical mechanical theories and computer simulation are reported. The authors have developed new theoretical equations of state for mixtures in which the...

K. E. Gubbins

1987-01-01

186

Molecular Theory and Computer Simulation Studies of Natural and Synthetic Gas Mixtures. Annual Report January 1, 1985-December 31, 1985.  

National Technical Information Service (NTIS)

Studies of bulk fluid mixtures and of liquid surface properties (liquid-gas and liquid-liquid) by statistical mechanical theories and computer simulation are reported. The authors have developed new theoretical equations of state for mixtures in which the...

K. E. Gubbins

1986-01-01

187

A kinetic ellipsoidal BGK model for a binary gas mixture  

NASA Astrophysics Data System (ADS)

An ellipsoidal BGK model is proposed for a binary mixture of rarefied gases in the frame of kinetic theory. It fulfils the crucial properties of the actual Boltzmann equation (collision invariants, equilibria, entropy dissipation), and introduces a further constraint on velocity equalization of the two species. The model features two disposable relaxation parameters which can be used to fit exactly, in the continuum limit, Fick's law for diffusion velocities and Newton's law for the viscous stress in the relevant set of Navier-Stokes equations. Positivity of temperature fields is guaranteed by a physically meaningful restriction on the parameters themselves.

Groppi, M.; Monica, S.; Spiga, G.

2011-12-01

188

Controlled pulse-etching with xenon difluoride  

Microsoft Academic Search

A gas-phase, room-temperature, plasmaless isotropic etching system has been used for bulk and thin film silicon etching. A computer controlled multi-chambered etcher is used to provide precisely metered pulses of xenon difluoride (XeF2) gas to the etch chamber. Etch rates as high as 15 microns per minute have been observed. The etch appears to have infinite selectivity to many common

Patrick B. Chu; Jeffrey T. Chen; Richard Yeht; Gisela Lin; Jeff C. P. Huang; B. A. Warneke; S. J. Pister

1997-01-01

189

Spectral emission measurements from planar mixtures of gas and particulates  

NASA Astrophysics Data System (ADS)

An experimental system is developed that forms a hot layer of gas and particulates flowing through a test section with cooled walls. The test section forms a one-dimensional planar layer, allows intrusive probes to characterize the medium in terms of particle loading and temperature, and allows radiometric measurements of the normally directed spectral energy emitted from the medium. Gas flow, gas composition, and particle flow are controlled. An experimental investigation is undertaken yielding spectral normally directed emittance data obtained from a well-characterized layer containing gaseous constituents of carbon dioxide and nitrogen, and solid particles of BNi-2, a boron nickel alloy. Emittance data are presented and exhibit the effects of particulate scattering, including the extension of the 4.3 microns carbon dioxide band wings. Emittance data are compared to analytical predictions.

Skocypec, R. D.; Walters, D. V.; Buckius, R. O.

1987-02-01

190

Magnetic resonance imaging of lungs at ultra-low magnetic field strength using hyperpolarized xenon-129 gas  

NASA Astrophysics Data System (ADS)

Conventional proton Magnetic Resonance (MR) imaging has been limited to water rich organs and tissues, with limited success in lungs and airways. With the introduction of Hyperpolarized Noble Gases (HNG's), the low spin concentration in gas-spaces is compensated by the extremely high non-equilibrium magnetizations achievable. This magnetization increase allows the use of field strengths much lower than those currently used in clinical MR systems with advantages such as: increased patient accessibility, reduced cost and image artifacts and less siting restrictions. Until now, the choice of field strength for HNG imaging has been mostly determined by the existing conventional MR systems or on hardware limitations. This work provides a theoretical framework for selection of the optimum field strength for clinical HNG MR imaging systems based on models of the field strength dependence of the achievable signal-to-noise ratio (SNR) and spatial resolution. A methodology for MR imaging of the lungs at very low field strengths is developed by building a system for hyperpolarized 129Xe (HXe) rat lung imaging that uses the fringe field of a superconducting magnet as the source of the static magnetic field. A passive shimming procedure that improves the fringe field homogeneity to the levels required for imaging is theoretically described and used at two field strengths (8.5 mT and 17 mT). Spectra and images of HXe gas in phantoms and excised rat lungs are presented and used to validate the obtained theoretical SNR field dependence for small samples. The issues related to clinical HNG imaging at low fields for both gas-space and dissolved-phase imaging are investigated and possible ways to address them in future are discussed.

Parra Robles, Juan Miguel

191

Steady-state electrode potentials of solid-electrolyte cells in reducing chemically nonequilibrium gas mixtures  

Microsoft Academic Search

The paper studies the steady-state potential response of the electrodes of solid-electrolyte cells with ZrO2 + 9 mol % Y2O3 in reducing nonequilibrium gas mixtures of N2 + H2 + H2O + O2 with a low content of O2 and in the mixtures of CH4 + CO2 + CO with a low content of CO, in the temperature range of

G. I. Fadeev; A. S. Kalyakin; S. I. Somov

2010-01-01

192

Weak discontinuity waves in a relativistic mixture of two stiffened gas components  

NASA Astrophysics Data System (ADS)

A simple interface-capturing approach is developed in order to deduce the relativistic fluid equations for a two-component mixture, using a stiffened gas equation of state. The two species are assumed to be at thermal equilibrium and the total pressure of the mixture is expressed in terms of the pressures of the two components by Dalton's law. Moreover, weak discontinuity waves compatible with such a fluid are examined.

Conforto, F.; Giambò, S.

2010-11-01

193

ARCFLO4 Simulation of H\\/He Gas Mixtures in High-Enthalpy Arc Heaters  

Microsoft Academic Search

The application of the ARCFLO4 code for modeling constricted arc heater performance with H\\/He gas mixtures is presented. The use of the constricted arc heater with H\\/He mixtures is being considered for simulating a tokamak divertor environment (J. Balboni, T. Munsat, S. Cohen, to appear in J. Nucl. Mater. Dec 1996.), as well as simulating entry conditions into outer planet

Tobin L. Munsat; S. A. Cohen; John Balboni; Ellis Whiting

1996-01-01

194

[Electroencephalogram, informational saturation of electroencephalogram, and bispectral index during xenon anesthesia for laparoscopic operations].  

PubMed

The depth of xenon anesthesia was never evaluated by modern methods of EEG monitoring, and hence, we studied changes in EEG, INEEG, and BIS during different stages of xenon narcosis and evaluated the possibility of using these values as criteria of xenon anesthesia adequacy. The study was carried out in 60 patients during laparoscopic operations on abdominal organs. The patients were divided into 2 groups receiving different gas anesthetics (xenon or nitric oxide). The results indicate that xenon monoanesthesia caused dose-dependent changes in the native and treated EEG; xenon is a good inhalation anesthetic providing adequate anesthesia for little traumatic operations even in case of mononarcosis; INEEG and BIS monitoring during xenon anesthesia allows an objective evaluation of its depth. PMID:12221874

Likhvantsev, V V; Volovik, A G; Petrov, O V; Sitnikov, A V; Subbotin, V V

195

Passive remote monitoring of multi-gas mixtures by FTIR radiometry  

NASA Astrophysics Data System (ADS)

The passive remote monitoring of multi-gas vapour mixtures by FTIR spectroscopy is investigated experimentally. The spectral radiance data were collected with the CATSI interferometer for a variety of multi-gas plumes at a distance of 60 m. Two basic sets of mixtures were studied. The first set corresponds to mixtures formed of three gases with no overlapping spectral bands (C2H2, C2H4 and R14). The second set corresponds to mixtures formed of three gases having overlapping spectral bands (C2H4, R114 and R134a). For each mixture the flow rates of individual constituents were adjusted to yield specific constituent CL ratios. These ratios are compared to the CL ratios retrieved from infrared radiance spectra. Results of this study indicate that for both sets of multi-gas mixtures the CL ratios retrieved by the passive remote monitoring technique agree well with those derived from the release flow rates. This good level of agreement was achieved by introducing a simple correction scheme to compensate for the limited accuracy of the fast radiance model implemented in the GASEM monitoring algorithm.

Thériault, Jean-Marc; Puckrin, Eldon; Lavoie, Hugo; Bouffard, Francois

2005-11-01

196

Remote monitoring of multi-gas mixtures by passive standoff Fourier transform infrared radiometry.  

PubMed

The passive remote monitoring of multi-gas mixtures was experimentally investigated using Fourier transform infrared (FT-IR) radiometry. The spectral radiance data were collected using a dual-port radiometrically balanced interferometer for a variety of multi-gas plumes at a standoff distance of 60 m. Two basic sets of mixtures were studied. The first set corresponded to mixtures consisting of three gases with no overlapping spectral bands (C(2)H(2), C(2)H(4), and R14). The second set corresponded to mixtures of three gases having significant spectral overlap (C(2)H(4), R114, and R134a). For each mixture the flow rates of individual constituents were adjusted to yield specific constituent optical-density (CL) ratios. These ratios were compared to the optical-density ratios retrieved from the measured infrared radiance spectra. Results of this study indicated that for both sets of multi-gas mixtures the optical-density ratios retrieved by the passive remote monitoring technique were in good agreement with those derived from the release flow rates, provided that a simple correction scheme was introduced to compensate for the limited accuracy of the fast radiance model implemented in the monitoring algorithm. PMID:17650375

Thériault, Jean-Marc; Puckrin, Eldon; Lavoie, Hugo

2007-06-01

197

Xenon recirculation systems for next-generation lithography tools  

NASA Astrophysics Data System (ADS)

Next generation lithography tools designed to pattern critical dimensions at <45nm will require extreme ultraviolet (EUV) light sources. Xenon is currently a strong candidate for the source medium for production of EUV light at 13.5nm. A consistent supply of ultra high purity xenon is required for efficient light source production. Several factors must be considered in the overall operating costs of the EUV tool: The high cost of xenon (typically ~$4/litre); The quantities required for EUV source production, which are typically 4slpm for Laser Produced Plasma (LPP) and 300sccm for Gas Discharge Produced Plasma (GDPP). On the basis of these figures the annual xenon cost would typically be approximately $11M/year for LPP, $1M/year for GDPP. Therefore recycling of xenon offers a significant operating cost reduction. This type of re-circulation system is not restricted to high xenon throughput applications, but can be scaled in size, and hence cost, for application to lower throughput process applications. Additional applications in mainstream silicon processing including a new development in dielectric etch using xenon could also benefit from re-circulation. Present research indicates that for a typical recipe, 675sccm xenon is required per wafer pass, this equates to an annual cost of $0.6M. BOC Edwards has designed & built a series of five fully integrated xenon re-circulation systems for lithography applications. Each system has been custom designed to exact application requirements, including liquid/solid xenon filament production. Additionally, an important footprint reduction has been achieved during the design evolution, which ideally suits dielectric etch applications.

Greenwood, Joanne R.; Mennie, Darren; Hughes, Carolyn; Lee, Ron

2004-05-01

198

Current filamentation in discharge-excited F{sub 2}-based excimer laser gas mixtures  

SciTech Connect

Discharge instabilities in x-ray preionized F{sub 2}-doped excimer laser gas mixtures are investigated using an intensified charge coupled device camera with a gating time of 300 ps. In contradiction with earlier theories and observations, it is found that the discharges in He/F{sub 2} mixtures are homogeneous only at very low concentration of F{sub 2} (0.025%). We present experimental results, which prove that in He/Kr/F{sub 2} mixtures the appearance of discharge filaments is coupled with the presence of F{sub 2} rather than Kr.

Mathew, D.; Bastiaens, H.M.J.; Boller, K.-J.; Peters, P.J.M. [Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

2006-03-06

199

Systematic calculations of the band structures of the rare-gas crystals neon, argon, krypton, and xenon  

NASA Astrophysics Data System (ADS)

Scalar relativistic self-consistent calculations of the band structure of Ne, Ar, Kr, and Xe have been performed with the augmented-plane-wave method using the Hedin-Lundqvist local-density (LD) expression for exchange and correlation. The trends with increasing atomic number in this inert-gas solid series are presented for the valence-band width, LD band gap, and for low-lying conduction-band eigenvalues. A simplified form of self-energy correction that accounts for dynamical exchange and correlation processes to the single-particle excitations is included. Comparisons are made with previous studies using different methods. The present approach is most reliable for valence-band properties and gives semiquantitative agreement with experimental values of the band-gap and conduction-band separations.

Bacalis, N. C.; Papaconstantopoulos, D. A.; Pickett, W. E.

1988-09-01

200

Selective removal of carbonyl sulfide from a hydrogen sulfide containing gas mixture  

SciTech Connect

This patent describes a process for the selective removal of carbonyl sulfide from a gas mixture also comprising hydrogen sulfide. It comprises contacting the gas mixture with an absorbent comprising from about 35% w to about 55% w of a tertiary amine; from about 5% w to about 15% w of water, and the balance being a physical co-solvent; regenerating the loaded absorbent to remove substantially all of the carbonyl sulfide and most of the hydrogen sulfide to provide a lean absorbent containing hydrogen sulfide in an amount of 0.2% w to 2% w; and recycling the lean absorbent to the contacting step.

Souby, M.C.

1990-12-25

201

Prediction of the phase state of a natural condensed gas mixture  

SciTech Connect

The authors have examined how the type of data on the fractional composition of debutanized gas condensate and the selection of a state equation can influence the prediction of the phase state of a natural condensed gas mixture. The authors have attempted to have the fractional composition of the mixture as found by single-pass evaporation approach that revealed by fractional distillation. The advantage of the vacancy quasichemical equation of states over the Redlich-Kwong-Soave equation in the calculation of phase equilibria has been shown.

Kuranov, G.L.; Pukinskii, I.B.; Smirnova, N.A.; Avdeev, D.Yu. [St. Petersburg State Univ. (Russian Federation)

1995-07-20

202

Process and installation for purification of the helium contained in a mixture of gas  

SciTech Connect

The present invention relates to a process and an installation for purification of the helium contained in a mixture of gas, employing a pre-treatment unit to retain the impurities such as water, carbon dioxide gas and heavy organic compounds, and at least one reactor of the chromatographic type located downstream of said pre-treatment unit, said process comprising the following steps of: (a) adjusting the pressure of the mixture of gas until the working pressure of the phase of adsorption is obtained, this pressure being between 10 and 30 bars, and preferably 12 to 15 bars; (b) taking the temperature of the mixture of gas at the outlet of said pre-treatment unit until it is located in the range -15/sup 0/ C./-35/sup 0/ C., and preferably -25/sup 0/ C.; (c) and sending the mixture of gas into the reactor and passing it through an absorbent, which is constituted by a microporous charcoal whose pores are of dimensions less than or equal to 20 A.

Avon, M.F.; Markarian, G.R.

1984-04-24

203

Modeling of the gas-phase chemistry in C-H-O gas mixtures for diamond chemical vapor deposition  

NASA Astrophysics Data System (ADS)

The boundaries of the diamond deposition region in the C-H-O (Bachmann) atomic phase composition diagram have been reproduced successfully for 38 different C, H, and O containing gas mixtures using the CHEMKIN computer package, together with just two criteria-a minimum mole fraction of methyl radicals [CH3] and a limiting value of the [H]/[C2H2] ratio. The diamond growth/no-growth boundary coincides with the line along which the input mole fractions of C and O are equal. For every gas mixture studied, no-growth regions are found to coincide with a negligible (<10-10) mole fraction of CH3 radicals, while for gas mixtures lying within the diamond growth region the CH3 mole fraction is ~10-7. Each no-growth-->diamond growth boundary is seen to be accompanied by a 2-3 order of magnitude step in CH3 mole fraction. The boundary between diamond and nondiamond growth is less clearly defined, but can be reproduced by assuming a critical, temperature dependent [H]/[C2H2] ratio (0.2, in the case that Tgas=2000 K) that reflects the crucial role of H atoms in the etching of nondiamond phases. The analysis allows prediction of the composition process window for good quality diamond growth for all stable input gas mixtures considered in this study.

Petherbridge, James R.; May, Paul W.; Ashfold, Michael N. R.

2001-05-01

204

A Study for Health Hazard Evaluation of Methylene Chloride Evaporated from the Tear Gas Mixture  

PubMed Central

This study explored the health hazard of those exposed to methylene chloride by assessing its atmospheric concentration when a tear gas mixture was aerially dispersed. The concentration of methylene chloride ranged from 311.1-980.3 ppm (geometric mean, 555.8 ppm), 30 seconds after the dispersion started. However, the concentration fell rapidly to below 10 ppm after dispersion was completed. The concentration during the dispersion did not surpass the National Institute for Occupational Safety and Health 'immediately dangerous to life or health' value of 2,300 ppm, but did exceed the American Conference of Governmental Industrial Hygienists excursion limit of 250 ppm. Since methylene chloride is highly volatile (vapor pressure, 349 mmHg at 20?), the postdispersion atmospheric concentration can rise instantaneously. Moreover, the o-chlorobenzylidenemalononitrile formulation of tear gas (CS gas) is an acute upper respiratory tract irritant. Therefore, tear gas mixtures should be handled with delicate care.

Chung, Eun-Kyo; Yi, Gwang-Yong; Chung, Kwang-Jae; Shin, Jung-Ah; Lee, In-Seop

2010-01-01

205

On-line analysis of complex hydrocarbon mixtures using comprehensive two-dimensional gas chromatography  

Microsoft Academic Search

This paper discusses the first setup for on-line qualitative and quantitative comprehensive two-dimensional gas chromatography (GC×GC) of complex hydrocarbon mixtures. A built-in 4-port 2-way valve allows switching between flame ionization detection (FID) and time-of-flight mass spectrometry (TOF-MS) between runs, without the need to cool down and vent the MS. Proper selection of GC carrier gas flow rates enables maximal agreement

Kevin M. Van Geem; Steven P. Pyl; Marie-Françoise Reyniers; Joeri Vercammen; Jan Beens; Guy B. Marin

2010-01-01

206

Kinetically enhanced copper vapour lasers employing H2-HCl-Ne buffer gas mixtures  

NASA Astrophysics Data System (ADS)

The output powers from 25 mm (volume 0.49 l) and 40 mm (volume 1.9 l) diameter copper vapour lasers (nominally 20 and 55 W devices) are approximately doubled to >50 and >100 W respectively by adding small partial pressures of both H2 and HCl to the neon buffer gas. Our studies show that this gas mixture performs better than a H2-HBr admix, a result we attribute to more efficient reassociation of HCl in the plasma region.

Withford, Michael J.; Brown, Daniel J. W.; Carman, Robert J.; Piper, James A.

1998-08-01

207

Diffusion and virial coefficient in a mercury-argon gas mixture  

NASA Astrophysics Data System (ADS)

Theoretical and experimental data on molecular beams and the mutual diffusion coefficient (MDC) and second virial coefficient (SVC) for an Hg-Ar gas mixture as a representative of the mercuryinert gas family are matched on basis of the Morse potential and the relations of the molecular kinetic theory of rarefied gases. Tables of the MDC and SVC values in the temperature range of 200-2000 K are calculated, and estimates of their accuracy are presented.

Popov, V. N.; Fokin, L. R.

2013-04-01

208

Corrosion of API 5L B and X52 in crude oil\\/water\\/gas mixtures  

Microsoft Academic Search

Laboratory and field tests were conducted to evaluate the corrosion behavior of API 5L grade B and X52 steels using Furrial's crude oil in the presence of water and gas containing carbon dioxide (COâ) and hydrogen sulfide (HâS). The results suggest that the corrosiveness of this crude oil\\/water\\/gas mixture is not detrimental to either steel. However, pitting corrosion was observed.

J. J. Perdomo; J. J. Gonzalez; A. Viloria; H. De Veer; Y. De Abreu

2000-01-01

209

Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids.  

PubMed

This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) at 40 degrees C and low pressures (approximately 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % [C2mim][BF4] in [C2mim][Tf2N]. Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO2 with N2 or CH4 in pure [C2mim][BF4] can be enhanced by adding 5 mol % [C2mim][Tf2N]. PMID:18247501

Finotello, Alexia; Bara, Jason E; Narayan, Suguna; Camper, Dean; Noble, Richard D

2008-02-02

210

PIXeY - Liquid Xenon R&D at Yale  

NASA Astrophysics Data System (ADS)

In recent years xenon has risen as a medium for particle detection, exhibiting a number of desirable qualities that make it well-suited for applications such as medical imaging, imaging of nuclear materials, and fundamental physics research. Xenon is a bright scintillator, with a fast (˜45 ns) response time, a large charge yield and high electron mobility. The high density (3 g/mL) and high atomic number (Z = 54) of liquid xenon make it ideal for detecting gamma rays with high efficiency over large energy ranges. PIXeY (Particle Identification in Xenon at Yale) is a compact, liquid-xenon-based TPC that operates in either single or two-phase (liquid/gas) mode and detects both charge and light signals produced by particle interactions within the detector. The initial goal of the experiment is to study xenon physics with implications for the operation and design for future large scale experiments (for dark matter or double beta decay), including energy resolution and event discrimination. This presentation will provide an overview of the experiment and discuss the xenon physics studies planned, the results so far and a brief overview of future plans.

Edwards, Blair; Bernard, Ethan; Cahn, Sidney; Larsen, Nicole; Lyashenko, Alexey; McKinsey, Daniel; Nikkel, James; Shin, Yunchang; Tennyson, Brian; Wahl, Christopher; Destefano, Nicholas; Gai, Moshe

2013-04-01

211

Ignition of a combustible gas mixture by a laser spark excited in the reactor volume  

SciTech Connect

Ignition of a stoichiometric CH{sub 4}: O{sub 2} mixture by a laser spark excited in the reactor volume is studied experimentally. It is found that the spark initiates a feebly radiating incomplete-combustion wave, which is much faster than the combustion wave, but is substantially slower than the detonation wave. With a time delay of 500-700 {mu}s, a bright optical flash occupying the entire chamber volume is observed, which indicates fast (involving branching chain reactions) ignition of the gas mixture. A conclusion is drawn regarding the common nature of the process of ignition of a combustible gas mixture by a laser spark excited in the reactor volume and the previously investigated initiation of combustion by laser sparks excited at solid targets, high-power microwave discharges, and high-current gliding discharges.

Kazantsev, S. Yu.; Kononov, I. G.; Kossyi, I. A.; Tarasova, N. M.; Firsov, K. N. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation)

2009-03-15

212

Growth Kinetics and Modeling of Direct Oxynitride Growth with NO-O2 Gas Mixtures  

SciTech Connect

We have modeled growth kinetics of oxynitrides grown in NO-O2 gas mixtures from first principles using modified Deal-Grove equations. Retardation of oxygen diffusion through the nitrided dielectric was assumed to be the dominant growth-limiting step. The model was validated against experimentally obtained curves with good agreement. Excellent uniformity, which exceeded expected walues, was observed.

Everist, Sarah; Nelson, Jerry; Sharangpani, Rahul; Smith, Paul Martin; Tay, Sing-Pin; Thakur, Randhir

1999-05-03

213

Computerised gas-liquid chromatography of bacterial cellular fatty acids in analysis of bacterial mixtures  

Microsoft Academic Search

Gas-liquid chromatography (GLC) of bacterial cellular fatty acids (CFA) was tested as a method to obtain species-specific information directly from multimicrobial samples. The CFA spectra of 145 mixtures containing 3, 4, 6 or 8 microbial species were produced by GLC. The idea of direct GLC of multibacterial samples is based on the assumption that the CFA composition of a sample

Leena Lehtonen; Reijo Peltonen; Erkki Eerola

1996-01-01

214

Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium  

Microsoft Academic Search

The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere

E. C. Anderson; J. N. Moss

1975-01-01

215

Gas transport properties of high free volume polyarylates based on isophthalic\\/terephthalic acid chloride mixtures  

Microsoft Academic Search

This paper reports the synthesis and the gas transport properties measured for polyarylates obtained by high temperature polycondensation of tetramethyl (TMBPA), hexafluoro (HFBPA) and tetramethyl hexafluoro (TMHFBPA) bisphenol A with a mixture of isophthalic (I) and terephthalic (T) acid chlorides (50mol% initial I\\/T ratio). The polymers show high glass transition temperature (above 180°C), good solubility in chlorinated solvents as well

M. T. Guzmán-Gutierrez; F. A. Ruiz-Treviño; M. Zolutukhin; S. Hernández-López; U. Scherf

2007-01-01

216

Accurate and precise coulometric determination of sulfur dioxide in compressed gas mixtures  

Microsoft Academic Search

Sulfur dioxide (SO2) in the atmosphere is a common pollutant and is a major contributor to the formation of acid rain. Accurate and precise determinations of SO2 in the atmosphere are essential to determine the magnitude of the problem. Reference gas mixtures such as NIST SRMs are an important part of the measurement procedure. Coulometry has been established as an

G. D. Mitchell; A. A. Bell

1991-01-01

217

Ion mobilities in Xe\\/Ne and other rare-gas mixtures  

Microsoft Academic Search

The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this

D. Piscitelli; A. V. Phelps; J. de Urquijo; E. Basurto; L. C. Pitchford

2003-01-01

218

Thermal preconditioning of coal\\/water mixtures for gas turbine applications  

Microsoft Academic Search

Thermal preconditioning of coal\\/water mixtures (CWM) is a process proposed for use with stationary gas turbine engines. The CWM is heated before delivery to the combustor to vaporize the water and to pyrolyze and devolatilize the coal prior to injection. The process offers a number of potential advantages. Engines can be started without the use of an auxiliary fuel system,

G. Roffe; G. Miller

1985-01-01

219

Approximation of flammability region for natural gas-air-diluent mixture.  

PubMed

The growing implementation of exhaust gas recirculation (EGR) in reducing NO(x) emissions of engine is of paramount motivation to perform a fundamental research on the flammability characteristics of fuel-air-diluent mixtures. In this work, the influences of EGR on the flammability region of natural gas-air-diluent flames were experimentally studied in a constant volume bomb. An assumption of critical burning velocity at flammability limit is proposed to approximately determine the flammability region of these mixtures. Based on this assumption, an estimation of the flammability map for natural gas-air-diluent mixtures was obtained by using the empirical formula of burning velocity data. The flammability regions of natural gas-air mixtures with EGR are plotted versus the EGR rate. From the comparison of estimated results and experimental measurements, it is suggested that the accuracy of prediction is largely dependent upon the formula of burning velocity used. Meanwhile, the influence of pressure on the critical burning velocity at flammability limit is also investigated. On the basis of the pressure dependence criterion, the estimation was performed for the circumstance of high temperature and pressure, and the prediction results still agree well with those of experiments. PMID:15990227

Liao, S Y; Jiang, D M; Huang, Z H; Cheng, Q; Gao, J; Hu, Y

2005-10-17

220

Design of a cyclone separator for the separation of gas-liquid mixtures  

Microsoft Academic Search

A procedure has been developed at the MIKhMe for the design of a hollow cyclone separator with a rectangular tangential inlet of the gas-liquid mixture near the bottom. The procedure is based on the results of theoretical and experimental investigations of the cyclone and allows one to determine the geometrical dimensions and the operating regime of the cyclone which corresponds

A. S. Zhikharev; A. M. Kutepov; V. V. Solov'ev

1985-01-01

221

Concentration measurement systems with stable solutions for binary gas mixtures using two flowmeters  

NASA Astrophysics Data System (ADS)

The previously proposed gas concentration measurement system (Yamazaki et al 2007 Meas. Sci. Technol. 18 2762-8) shows a considerable error for some combinations of gases. The error increases when the system of equations determining mole fractions becomes a mathematically ill-conditioned system. Because the parameters of the equations reflect the material properties of the gases, the current paper considers flowmeters whose flow rate indication does not involve any gas property. This paper firstly illustrates the ill condition for the combination of venturi meter and laminar flowmeters. The paper then discusses the simultaneous measurement of flow rate and mole fractions by flowmeter combinations: an ultrasonic flowmeter and a venturi meter, an ultrasonic flowmeter and a laminar flowmeter. Experiments are conducted for a mixture of argon and air. When a venturi meter and a laminar flowmeter are used, the equations to evaluate the gas mixture ratio become an ill-conditioned system, and hence the evaluated mixture ratio shows a considerable error. On the other hand, the combination of an ultrasonic flowmeter and a laminar flowmeter detects the gas mixture ratio with proper accuracy.

Youn, Chongho; Kawashima, Kenji; Kagawa, Toshiharu

2011-06-01

222

10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.  

Code of Federal Regulations, 2013 CFR

...annual Btu heat input of the primary energy sources needed to maintain operational...for the use of a mixture of solar energy (including wind, tide, and other intermittent...natural gas, where: (1) Solar energy will account for at least 20...

2013-01-01

223

Equations of motion of a gas mixture in the presence of chemical reactions  

Microsoft Academic Search

Equations of multicomponent, multivelocioty gasdynamics taking physical and chemical transformations into account are obtained for a multicomponent gas mixture with a small addition of charged particles in a strong electric field. The charged particles serve to excite specific internal energy states of the neutral molecules, and chemical reactions occur between the neutral molecules. It is shown that, when there are

V. Iu. Velikodnyi

1990-01-01

224

An Application of Space-Based Gas Mixtures for Joule-Thompson Cryocoolers  

Microsoft Academic Search

An extension of deepspace research, specifically, the work done on Alpha program, will inevitably require new and different cryostating systems. The primary differences will be in the areas of cooling power and temperature. One variant which can be used with J-T cryocoolers is the application of diverse gas mixtures which can work over a large temperature range. We have found

V. T. Arkhipov; O. V. Yevdokimova; M. P. Lobko; V. V. Yakuba

1999-01-01

225

Modeling of dense gas–solid reactive mixtures applied to biomass pyrolysis in a fluidized bed  

Microsoft Academic Search

A model is presented for mathematically describing the thermofluid dynamics of dense, reactive, gas–solid mixtures. The model distinguishes among multiple particle classes, either on the basis of their physical properties (diameter, density) or through their thermochemistry (reactive versus inert particles). A multifluid approach is followed where macroscopic equations are derived from the kinetic theory of granular flows using inelastic rigid-sphere

D. Lathouwers; J. Bellan

2001-01-01

226

Application of compressibility factors for high ratio carbon dioxide-methane gas mixtures  

Microsoft Academic Search

Compressibility factors for a high-ratio COâ-natural gas mixture, measured in a visual PVT cell, are compared with other experimental data and values calculated with 2 correlations. The correlations diverge from the experimental results near the critical region. Discussion includes how compressibility factors effect compressor cylinder sizing and related horsepower requirements. Also discussed are the factors used in monitoring reservoir performance

C. J. Fesmire; R. M. Dicharry; R. Simon; F. H. Vorhis

1974-01-01

227

Experimental determination of the Townsend coefficient for Argon-CO2 gas mixtures at high fields  

NASA Astrophysics Data System (ADS)

The first Townsend coefficient for Ar-CO2 based gas mixtures has been measured over a wide range of reduced electric field. The experimental setup and the measurement technique are described here. A linear superposition model has also been successfully applied.

Auriemma, G.; Fidanza, D.; Pirozzi, G.; Satriano, C.

2003-11-01

228

Hydrocracking of vacuum gas oil-vegetable oil mixtures for biofuels production.  

PubMed

Hydrocracking of vacuum gas oil (VGO)--vegetable oil mixtures is a prominent process for the production of biofuels. In this work both pre-hydrotreated and non-hydrotreated VGO are assessed whether they are suitable fossil components in a VGO-vegetable oil mixture as feed-stocks to a hydrocracking process. This assessment indicates the necessity of a VGO pre-hydrotreated step prior to hydrocracking the VGO-vegetable oil mixture. Moreover, the comparison of two different mixing ratios suggests that higher vegetable oil content favors hydrocracking product yields and qualities. Three commercial catalysts of different activity are utilized in order to identify a range of products that can be produced via a hydrocracking route. Finally, the effect of temperature on hydrocracking VGO-vegetable oil mixtures is studied in terms of conversion and selectivity to diesel, jet/kerosene and naphtha. PMID:19231171

Bezergianni, Stella; Kalogianni, Aggeliki; Vasalos, Iacovos A

2009-02-23

229

Removal of carbon dioxide from gas mixtures by wollastonite  

NASA Astrophysics Data System (ADS)

Wollastonite synthesis and decomposition were analyzed from the viewpoint of thermodynamics (using the TERRA software). It is shown that wollastonite synthesis from limestone and silica takes place at a minimum content of nitrogen (10-5 N2) with a release of carbon dioxide. The synthesis temperature is T ? 560 K. Wollastonite is decomposed in the presence of flue gas (4N2) with limestone and silica formation and burial of carbon dioxide in the form of CaCO3(c). Wollastonite decomposition temperature is T ? 420 K. The cyclic reciprocating process for complete removal of carbon dioxide by wollastonite is suggested. Four strokes of the reciprocating system with the fixed temperatures of wollastonite decomposition (T=300 K) and wollastonite synthesis (T=560 K) are presented. Total energy consumption (T = 560 K) is ? I ? 130 kJ/mole, 30 % of energy is spent for heating and 70 % of energy is spent for chemical reaction. This is comparable with the heat of CO2 solution in ethanolamin.

Engelsht, V. S.; Muratalieva, V. Zh.

2013-09-01

230

Adsorption of gas mixtures on fixed bed. Application to fuel-gas valorisation.  

National Technical Information Service (NTIS)

Gas separation by adsorption is studied for recovery of LPG in fuel-gas from refineries. First theoretical calculations are presented taking into account modifications induced by variation of gas rate due to adsorption or desorption: Front formation for a...

A. Bossy

1987-01-01

231

Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches  

DOEpatents

An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

Christophorou, L.G.; Hunter, S.R.

1990-06-26

232

Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches  

DOEpatents

An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

Christophorou, Loucas G. (Oak Ridge, TN); Hunter, Scott R. (Oak Ridge, TN)

1990-01-01

233

Preparation of Calibration Gas Mixtures Using a Dynamic Volumetric Method for Environmental Monitoring  

NASA Astrophysics Data System (ADS)

It is difficult to produce and maintain the quality of calibration gas mixtures stable and reliable in gas cylinders for the identification and quantification of trace environmental contaminants. Dynamic method has attracted an attention because immediate and on-site generation of calibration gas mixture is achievable in the range of percent, sub-ppm, and micro-mole fraction. The dynamic method for the preparation of standard reference gas/vapour mixtures was carried out using polymeric permeation membrane. Permeation behaviour of various organic compounds including aliphatic and aromatic hydrocarbons and chlorohydrocarbons was tested through semi-permeable silicone polymer and fluoropolymers. Experimental results showed the constant permeation rate of target compounds under the constant temperature condition. The permeation rate, however, was largely influenced by chemical components, membrane materials, and temperature change. Mole fractions of generated vapour were calculated using the mass loss of permeation tubes and mass-flow rate of carrier gas. Dynamic volumetric techniques can be applicable for the generation of standard reference materials for the calibration of various types of organics (volatile organic compounds, polycyclic aromatic hydrocarbons, etc) in ambient air and water. This technology is also applicable to develop novel materials for passive samplers for long-term environmental monitoring.

Lee, S.; Lee, W.; Oh, S.

2008-12-01

234

Prospects for Barium Tagging in Gaseous Xenon  

NASA Astrophysics Data System (ADS)

Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification.

Sinclair, D.; Rollin, E.; Smith, J.; Mommers, A.; Ackeran, N.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Cook, S.; Coppens, A.; Daniels, T.; DeVoe, R.; Dobi, A.; Dolinski, M. J.; Donato, K.; Fairbank, W., Jr.; Farine, J.; Giroux, G.; Gornea, G.; Graham, K.; Gratta, G.; Green, M.; Hagemann, C.; Hall, C.; Hall, K.; Hallman, D.; Hargrove, C.; Herrin, S.; Kaufman, L. K.; Leonard, D. S.; LePort, F.; Mackay, D.; MacLennan, R.; Mong, B.; Montero Díez, M.; Müller, A. R.; Neilson, R.; Niner, E.; Odian, A.; O'Sullivan, K.; Ouellet, C.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Pushkin, K.; Rowson, P. C.; Slutsky, S.; Stekhanov, V.; Twelker, K.; Voskanian, N.; Vuilleumier, J.-L.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

2011-08-01

235

Diagnostics of water-containing gas mixtures using thermal laser-induced gratings  

NASA Astrophysics Data System (ADS)

Laser-induced gratings (LIGs) experiments, employing vibrational-overtone excitation of H2O molecules through rovibrational transitions of the (2 1 1) ? (0 0 0) band around 820 nm to produce gratings, have been performed in humid ambient air, in a room-temperature cell with neat water vapor or that diluted in buffer gas at pressures of 0.02 4 bar, and in the vicinity of premixed atmospheric pressure CH4-air flame, with the aim to investigate the feasibilities of the techniques for accomplishing gas diagnostics or tracing H2O at various temperatures and pressures. In highly vibrationally-excited H2O rapid multi-stage collisional thermalization processes occur, and as a result both strong oscillatory (due to standing acoustic waves) and stationary (due to stationary density modulations) contributions to LIGs have been observed in gas mixtures. Temporal profiles of LIG signals recorded at various conditions of gas mixtures employed have been analysed in frame of a model of a two- or three-stage R T, V V?, and V T collisional relaxation of H2O and buffer gas molecules. The informative parameters, like adiabatic sound velocity, gas temperature, H2O mole fraction have been derived. The results of the analysis are presented, demonstrating possibilities and challenges of the technique in application to gas diagnostics.

Hemmerling, B.; Kozlov, D. N.; Stel'Makh, O. M.; Attal-Trétout, B.

2006-01-01

236

Converging xenon shock waves driven by megagauss magnetic fields  

SciTech Connect

We attempted to implode a conducting metal linear at high velocity, and our failure to do so led to switching, or rapidly transferring the field from pushing an aluminum conductor to snow-plowing a half-atmosphere of xenon gas. We successfully initiated convergent xenon gas shocks with the use of a magnetohydrodynamic switch and coaxial high-explosive, flux-compression generators. Principal diagnostics used to study the imploding xenon gas were /sup 133/Xe radioactive tracers, continuous x-ray absorption, and neutron output. We compressed the xenon gas about five to sixfold at a velocity of 10 cm/..mu..s at a radius of 4 cm. The snowplow efficiency was good; going from 13- to 4-cm radius, we lost only about 20% of the mass. The temperature of the imploded sheath was determined by mixing deuterium with the xenon and measuring the neutron output. Using reasonable assumptions about the amount, density, and uniformity of the compressed gas, we estimate that we reached temperatures as high as 155 eV. Energy-loss mechanisms that we encountered included wall ablation and Taylor instabilities of the back surface.

Shearer, J.W.; Steinberg, D.J.

1986-07-01

237

[O] [H] functionalization on carbon nanotube using (O2-H2) gas mixture DC glow discharge  

NASA Astrophysics Data System (ADS)

The [O] [H] functionalization of carbon nanotube (CNT) was studied using oxygen-hydrogen (O2-H2) gas mixture direct current (DC) glow discharge plasma technique for cathode/CNT-anode separation of 0.10 ± 0.01 cm. O2 and H2 were fixed at flowrate of 10.0 ml/min in order to obtain gas mixture ratio of 1:1. During the (O2-H2) gas mixture DC glow discharge, current-voltage ( I- V) characteristic of gaseous species studied for various settings of gas pressures 1, 2, 3 and 4 mbar. The voltage at gap between cathode/CNT and anode, a breakdown voltage, was identified as "functionalization voltage" ( V func). V func was noticed responsible for functionalization of functional groups on sidewall of CNT. The V func were recorded as 796, 707, 594, and 663 V for gas pressures of 1, 2, 3 and 4 mbar, respectively. The co-relation between V func and gas pressure was identified as linear relationship. But a voltage obtained due to the CNT/Cathode fall shows exponential relationship with the gas pressures. The possibility of [O] [H] functionalization was proved using Fourier transmission infra-red (FTIR) spectroscopy. Hydroxyl (-OH), carboxyl (-COOH), and carbonyl (-C=O) functional groups were identical as identified in the FTIR spectra. The field emission scanning electron microscope images show significant changes in the morphology of CNT which proves that the DC gas discharge plasma is a possible technique for [O] [H] functionalization on the sidewall of CNT.

Thandavan, Tamil Many K.; Wong, Chiow San; Gani, Siti Meriam Abdul; Nor, Roslan Md

2012-03-01

238

Specific frequency integration method applied to thermally nonhomogeneous hydrogen-helium gas mixture.  

NASA Astrophysics Data System (ADS)

A frequency integration method applied to the calculation of total radiative quantities in thermally inhomogeneous hydrogen-helium gas mixture is presented. First, the absorption spectrum of an hydrogen-helium gas mixture at high temperature (in the range 3000-30,000 K) has to be determined. Consequently, a review of the theoretical determination of the hydrogen-helium gas mixture absorption properties is performed under the assumption of local chemical and thermodynamical equilibria for a given set of temperature, pressure and initial molar fractions of the mixture. Cross-sections calculations are presented for the following absorption optical processes: electronic transitions bound-free and free-free of the negative hydrogen ion, bound-free, free-free and bound-bound of the hydrogen atom and the determination of the exact lines shapes is carefully detailed in the framework of three models. The frequency integration method suitable for the hydrogen-helium absorption coefficient spectrum is based on a spectral data bank that makes it fast and accurate. Absorbing and emitting radiative properties resulting from the model are checked in the case of a parallel plane layer with prescribed temperature whose the exact solution is known. A study on the different spectral ranges contribution in the radiative source and the net radiative flux near the walls is performed. Then, the appropriated choice of the lines calculation model is discussed.

Vaillon, R.; Lallemand, M.; Stehle, C.

1997-09-01

239

Calculation of the thermodynamic properties of gas and liquid solutions - Mixtures of complex substances  

NASA Astrophysics Data System (ADS)

Reference is made to a previous study (Kessel'man et al., 1986) in which a method has been proposed for calculating the thermodynamic properties of gas and liquid solutions in the one- and two-phase regions on the basis of a unified equation of state. Here, by using an effective intermolecular potential with temperature-dependent parameters, this method is extended to the calculation of the thermodynamic parameters of mixtures with complex components. Results are presented for a number of mixtures, including Ar+CO2, Ar+N2, N2+CH4, N2C2C6, CH4+CO2, and CH4+C4H10.

Kessel'Man, P. M.; Tkachenko, V. V.; Ugol'Nikov, A. P.

1987-12-01

240

The XENON Dark Matter Search  

NASA Astrophysics Data System (ADS)

The XENON experiment will search for Weakly Interacting Massive Particles (WIMPS), a leading candidate for the dark matter content of the Universe. The XENON detector uses the simultaneous measurement of ionization and scintillation in liquid xenon to distinguish between nuclear recoils and background electronic interactions. Ionization electrons are extracted into the xenon vapor where they produce a large proportional scintillation signal in a grid assembly. Both prompt and proportional scintillation light are detected by PMT arrays on the top and bottom of the active liquid xenon volume. The distribution of proportional scintillation light in the top PMT array can be used to achieve xy position resolution, while the ionization drift time gives position resolution in the z direction. This allows the definition of a low-background fiducial volume. I describe the results of the R&D phase of this project before providing a status update on the XENON10 phase.

McKinsey, D. N.

2006-11-01

241

Status of XENON100  

NASA Astrophysics Data System (ADS)

XENON100 is a two-phase time projection chamber with a 62 kg liquid xenon target to search for Dark Matter interactions. Both scintillation and ionization signals are recorded to allow interaction vertex reconstruction in three dimensions. Fiducialization of the target volume results in the lowest background level of any running Dark Matter search experiment. In a 48 kg fiducial target and 100.9 days of live time, no evidence for Dark Matter is found. This leads to the strongest limit on elastic spin-independent WIMP-nucleon interactions for WIMP masses above ~ 10 GeV/c2. Also, this data excludes inelastic Dark Matter scattering off sodium or iodine as an explanation of the DAMA modulation.

Lang, Rafael F.; XENON100 Collaboration

2012-07-01

242

Nuclear spin relaxation of {sup 129}Xe due to persistent xenon dimers  

SciTech Connect

We have measured longitudinal nuclear relaxation rates of {sup 129}Xe in Xe-N{sub 2} mixtures at densities below 0.5 amagats in a magnetic field of 8.0 T. We find that intrinsic spin relaxation in this regime is principally due to fluctuations in the intramolecular spin-rotation (SR) and chemical-shift-anisotropy (CSA) interactions, mediated by the formation of {sup 129}Xe-Xe persistent dimers. Our results are consistent with previous work done in one case at much lower applied fields where the CSA interaction is negligible and in another case at much higher gas densities where transient xenon dimers mediate the interactions. We have verified that a large applied field suppresses the persistent-dimer mechanism, consistent with standard relaxation theory, allowing us to measure room-temperature gas-phase relaxation times T{sub 1} for {sup 129}Xe greater than 25 h at 8.0 T. These data also yield a maximum possible low-field T{sub 1} for pure xenon gas at room temperature of 5.45{+-}0.2 h. The coupling strengths for the SR and CSA interactions that we extract are in fair agreement with estimates based both on previous experimental work and on ab initio calculations. Our results have potential implications for the production and storage of large quantities of hyperpolarized {sup 129}Xe for use in various applications.

Berry-Pusey, B. N.; Anger, B. C.; Laicher, G.; Saam, B. [Department of Physics, University of Utah, Salt Lake City, Utah 84112-0830 (United States)

2006-12-15

243

Stability assessment of gas mixtures containing terpenes at nominal 5 nmol/mol contained in treated aluminum gas cylinders.  

PubMed

Studies of climate change increasingly recognize the diverse influences exerted by terpenes in the atmosphere, including roles in particulates, ozone formation, and their oxidizing potential. Measurements of key terpenes suggest atmospheric concentrations ranging from low pmol/mol (parts per trillion) to nmol/mol (parts per billion), depending on location and compound. To accurately establish concentration trends, assess the role of terpenes in atmospheric chemistry, and relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. The feasibility of preparing well-characterized, stable gas cylinder standards for terpenes at the nmol/mol level is not yet well established. Several of the world's National Metrology Institutes (NMIs) are researching the feasibility of developing primary and secondary reference gas standards at the nmol/mol level for terpenes. The US NMI, the National Institute of Standards and Technology, has prepared several nmol/mol mixtures, in treated aluminum gas cylinders, containing terpenes in dry nitrogen at nominal 5 nmol/mol for stability studies. Overall, 11 terpenes were studied for stability. An initial gas mixture containing nine terpenes, one oxygenate, and six aromatic compounds, including benzene as an internal standard, was prepared. Results for four of the nine terpenes in this initial mixture indicate stability in these treated aluminum gas cylinders for over 6 months and project long term (years) stability. Interesting results were seen for beta-pinene, which when using a linear equation rate decline predicts that it will reach a zero concentration level at day 416. At the same time, increases in alpha-pinene, D: -limonene (R-(+)-limonene), and p-cymene were observed, including camphene, a terpene not prepared in the gas mixture, indicating a chemical transformation of beta-pinene to these species. Additional mixtures containing combination of either alpha-pinene, camphor, alpha-terpinene, and benzene indicate a second-order quadratic rate decline for the alpha-pinene and alpha-terpinene, a linear rate decline for camphor, and a second-order quadratic rate increase of camphene. PMID:20694720

Rhoderick, George C

2010-08-09

244

TMGAS: A new TOUGH2 EOS module for the numerical simulation of gas mixtures injection in geological structures  

Microsoft Academic Search

Injection of gas mixtures in geological structures is performed for a variety of different purposes including natural gas storage operations, CO2 flooding and Water Alternate Gas injection for Enhanced Oil Recovery, and more recently for the sequestration of GreenHouse Gases and the disposal of acid gases produced by sour hydrocarbon reservoirs. The injection of multi-component mixtures into saline aquifers and

Alfredo Battistelli; Marica Marcolini

2009-01-01

245

Experimental study and kinetics modeling of gas hydrate formation of methane-ethane mixture  

NASA Astrophysics Data System (ADS)

In this study, gas hydrate formation kinetics of methane and ethane binary mixtures has been studied and data of mixed methane-ethane hydrate formation at 0.1, 0.2, 0.3, 0.5, 0.68, 0.8, and 0.9 mole fractions of methane and at a temperature of 277.15 K and an initial pressure of approximately 3.6 MPa were collected. The thermodynamic natural path was used for modeling the hydrate formation rate in a constant volume process. The results show that there is good agreement between model prediction and experimental data, with an average error of 0.9%. It was observed that the values of these parameters are dependent on the concentration of components in the mixtures. The results indicate that this model can predict constant volume experimental data of binary mixture hydrate.

Naeiji, Parisa; Varaminian, Farshad

2013-09-01

246

Photoionization detector for the detection of xenon light  

SciTech Connect

A photionization detector is described with a high quantum efficiency at wavelengths shorter than about 2000 A. This instrument, coupled to a xenon gas scintillation proportional counter has an energy resolution of 9.5% FWHM at 6 keV. The vapor pressure and absorption coefficient of TMAE are measured and the prospects of an imaging gas scintillation proportional counter are discussed.

Anderson, D.F.

1980-01-01

247

A xenon ionization detector for digital radiography.  

PubMed

Xenon gas x-ray detectors have been used successfully in CT scanners; however, they have been found to be unsuitable for digital radiography. We have designed and built a new type of xenon x-ray detector array and tested its suitability for digital radiography. The detector consists of two parallel plates separated by a 0.5-mm gap, filled with xenon gas at a pressure of about 30 atm. One of the plates is the high-voltage electrode, while the other is a circuit board etched to form an array of metal collector strips focused on the x-ray source. Since there are no metal septa separating the individual detector elements, the dose efficiency of the detector is high, but image degradation will occur due to cross-talk between detector elements. Measurements of the cross-talk show that about an 18% reduction in contrast will occur, when a low contrast object, subtending one detector element, is imaged. We have also measured a detector MTF of 14% at 2 lp/mm, a signal of 10 pC for a 1-mR x-ray exposure at the detector entrance, a 6% nonlinearity in the detector signal over about 3 orders of magnitude in x-ray exposure, and a charge collection time (time response) of about 0.1 ms. From these results it is concluded that this new detector design is feasible for digital radiography. PMID:7087908

Drost, D J; Fenster, A

248

Kinetic Solution of the Structure of a Shock Wave in a Non-Reactive Gas Mixture  

NASA Astrophysics Data System (ADS)

The multi-species Boltzmann equation is numerically integrated to characterize the internal structure of a Mach 3 shock wave in a hard sphere gas. The collision integral is evaluated by the conservative discrete ordinate method of Tcheremissine [1]. There was excellent agreement of macroscopic variables with those of Kosuge, Aoki, and Takata. [2] The effect of species concentration and mass ratio on the behavior of macroscopic variables and distribution functions in the structure of the shock wave is considered for both two and three-species gas mixtures. In a binary mixture of gases with different masses and varying concentrations, the temperature overshoot of the parallel component of temperature near the center of the shock wave is highest for the heavy component when the concentration of the heavy component is the smallest. A physical basis for the temperature overshoot is put forth.

Josyula, Eswar; Vedula, Prakash; Bailey, William F.; Suchyta, Casimir J.

2011-05-01

249

Kinetic solution of the structure of a shock wave in a nonreactive gas mixture  

NASA Astrophysics Data System (ADS)

The multispecies Boltzmann equation is numerically integrated to characterize the internal structure of a Mach 3 shock wave in a hard sphere gas. The collision integral is evaluated by the conservative discrete ordinate method [F. G. Tcheremissine, Comput. Math. Math. Phys. 46, 315 (2006)]. There was excellent agreement of macroscopic variables [Kosuge et al.., Eur. J. Mech. B/Fluids 20, 87 (2001)]. The effect of species concentration and mass ratio on the behavior of macroscopic variables and distribution functions in the structure of the shock wave is considered for both two- and three-species gas mixtures. In a binary mixture of gases with different masses and varying concentrations, the temperature overshoot of the parallel component of temperature near the center of the shock wave is highest for the heavy component when the concentration of the heavy component is the smallest. The rise in the parallel component of temperature is revealed by the behavior of the distribution function.

Josyula, Eswar; Vedula, Prakash; Bailey, William F.; Suchyta, Casimir J.

2011-01-01

250

Cryotrapping assisted mass spectrometry for the analysis of complex gas mixtures  

SciTech Connect

A simple method is described for the unambiguous identification of the individual components in a gas mixture showing strong overlapping of their mass spectrometric cracking patterns. The method, herein referred to as cryotrapping assisted mass spectrometry, takes advantage of the different vapor pressure values of the individual components at low temperature (78 K for liquid nitrogen traps), and thus of the different depletion efficiencies and outgassing patterns during the fast cooling and slow warming up of the trap, respectively. Examples of the use of this technique for gas mixtures with application to plasma enhanced chemical vapor deposition of carbon and carbon-nitrogen hard films are shown. Detection of traces of specific C{sub 3} hydrocarbons (<50 ppm of initial methane) in methane/hydrogen plasmas and the possible trapping of thermally unstable C-N compounds in N{sub 2} containing deposition plasmas are addressed as representative examples of specific applications of the technique.

Ferreira, Jose A.; Tabares, Francisco L. [Laboratorio Nacional de Fusion por Confinamiento Magnetico, CIEMAT, Avda Complutense 22, Madrid 28040 (Spain)

2007-03-15

251

[Effect of krypton-containing gas mixture on Japanese quail embryo development].  

PubMed

Investigated were effects of gas mixture with up to 3.0 kgs/cm2 of krypton on the embryonic development of domesticated Japanese quail (Coturnix coturnix japonica dom.). Results demonstrated absence of a serious krypton effect on Japanese quail embryos. Development of embryos proceeded in due course; morphometrically the experimental embryos were essentially similar to controls. It should be noted that despite exposure to acute hypoxic hypoxia during the initial 12 hours of development in the krypton-containing gas mixture, viability of quail embryos was high enough which can be ascribed to the krypton protective action. Besides, an additional experiment showed that krypton partial pressure of 5-5.5 kgs/cm2 produces the narcotic effect on adult Japanese quails. PMID:18564569

Kussmaul', A R; Gur'eva, T S; Dadasheva, O A; Pavlov, N B; Pavlov, B N

252

ARCFLO4 Simulation of H/He Gas Mixtures in High-Enthalpy Arc Heaters  

NASA Astrophysics Data System (ADS)

The application of the ARCFLO4 code for modeling constricted arc heater performance with H/He gas mixtures is presented. The use of the constricted arc heater with H/He mixtures is being considered for simulating a tokamak divertor environment (J. Balboni, T. Munsat, S. Cohen, to appear in J. Nucl. Mater. Dec 1996.), as well as simulating entry conditions into outer planet atmospheres. The first step is to model the arc discharge within the constrictor column using ARCFLO4 to find plasma conditions typical of detached plasmas in divertors; 1 GW/m^2 power flow and densities > 10^15 cm-3, as expected in ITER. To achieve this, a database of thermodynamic, transport, and radiation properties of H/He mixtures as a function of temperature, pressure, and gas composition was prepared, and ARCFLO4 was run using the H/He property tables relevant to a possible dedicated H/He facility at NASA-ARC. The properties input to the code are enthalpy, density, molar species fraction, viscosity, thermal and electrical conductivity, and bulk spectral absorption coefficients, over the ranges 1000Kmixtures. Samples of the new H/He database and results of various test runs of ARCFLO4 using this data are presented.

Munsat, Tobin L.; Cohen, S. A.; Balboni, John; Whiting, Ellis

1996-11-01

253

Two-Dimensional Gas-Phase Separations Coupled to Mass Spectrometry for Analysis of Complex Mixtures  

SciTech Connect

Ion mobility spectrometry (IMS) has been explored for decades, and its versatility in separation and identification of gas-phase ions, including in isomeric mixtures, is well established. Recently, field asymmetric waveform IMS (FAIMS) has been gaining acceptance in similar applications. Coupled to mass spectrometry (MS), both IMS and FAIMS have shown the potential for broad utility in proteomics and other biological analyses. A major attraction of these separations is extremely high speed, exceeding that of condensed-phase alternatives by orders of magnitude. However, modest separation peak capacities have limited the utility of FAIMS and IMS for analyses of complex mixtures. We report 2-D gas-phase separations that join FAIMS to IMS, in conjunction with high-resolution and accuracy time-of-flight MS. Evaluation of FAIMS/IMS/TOF performance using a protein mixture tryptic digest reveals high orthogonality between FAIMS and IMS dimensions, and hence the benefit of FAIMS filtering prior to IMS/MS. The effective overall peak capacities are {approx}500 for FAIMS/IMS separations, and {approx}106 for 3-D FAIMS/IMS/MS analyses of tryptic peptides. Implementation of FAIMS/IMS and IMS/MS interfaces using electrodynamic ion funnels greatly improves sensitivity, making FAIMS/IMS/MS a potential platform for ultrahigh-throughput analyses of complex mixtures.

Tang, Keqi; Li, Fumin; Shvartsburg, Alexandre A.; Strittmatter, Eric F.; Smith, Richard D.

2005-10-01

254

Process and catalyst for converting synthesis gas to liquid hydrocarbon mixture  

DOEpatents

Synthesis gas containing CO and H.sub.2 is converted to a high-octane hydrocarbon liquid in the gasoline boiling point range by bringing the gas into contact with a heterogeneous catalyst including, in physical mixture, a zeolite molecular sieve, cobalt at 6-20% by weight, and thoria at 0.5-3.9% by weight. The contacting occurs at a temperature of 250.degree.-300.degree. C., and a pressure of 10-30 atmospheres. The conditions can be selected to form a major portion of the hydrocarbon product in the gasoline boiling range with a research octane of more than 80 and less than 10% by weight aromatics.

Rao, V. Udaya S. (Monroeville, PA); Gormley, Robert J. (Pittsburgh, PA)

1987-01-01

255

FIRE SUPPRESSION EFFICIENCY OF BROMOALKENE\\/NITROGEN GAS MIXTURES AS TOTAGFLOODING AGENTS  

Microsoft Academic Search

The tire suppression efiiciencies of I-bromo-I-propene I nitrogen and 2-bromo-3,3,3 trifluoro-I-propene I nitrogen gas mixtures as total-flooding agents were studied by a cup-burner method. It was shown that addition of small amounts of I-bromo-I-propene and 2-bromo-3,3,3 trifluoro-I-propene to nitrogen can improve the suppression effectiveness of the inert gas by 34 and 64% respectively. An arrangement for mixing organic compounds with

Yong Zou; Nader Vahdat; Michelle M. Collins

256

Corrosion of API 5L B and X52 in crude oil/water/gas mixtures  

SciTech Connect

Laboratory and field tests were conducted to evaluate the corrosion behavior of API 5L grade B and X52 steels using Furrial's crude oil in the presence of water and gas containing carbon dioxide (CO{sub 2}) and hydrogen sulfide (H{sub 2}S). The results suggest that the corrosiveness of this crude oil/water/gas mixture is not detrimental to either steel. However, pitting corrosion was observed. The low general corrosion rates measured were attributed to the natural inhibiting properties of the crude oil.

Perdomo, J.J.; Gonzalez, J.J.; Viloria, A.; De Veer, H.; De Abreu, Y.

2000-02-01

257

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

258

Performance of resistive plate counters with freonless gas mixtures for measurements of cosmic ray muons  

Microsoft Academic Search

Various operational features of bakelite Resistive Plate Counters with a bulk resistivity of 1012?cm are studied with different argon, methane and isobutane mixtures, but avoiding freon as counter gas contribution. The efficiency and the time resolution of the detector as well as the cross-talk behavior of neighbored read-out pads are investigated for different voltages by use of cosmic ray muons.

S. Ganter; J. Wentz; A. Haungs; H. J. Mathes; H. Rebel

1998-01-01

259

Heliumoxygen mixture does not improve gas exchange in mechanically ventilated children with bronchiolitis  

Microsoft Academic Search

STATEMENT OF FINDINGS: Varying concentrations of helium-oxygen (heliox) mixtures were evaluated in mechanically ventilated children with bronchiolitis. We hypothesized that, with an increase in the helium:oxygen ratio, and therefore a decrease in gas density, ventilation and oxygenation would improve in children with bronchiolitis. Ten patients, aged 1-9 months, were mechanically ventilated in synchronized intermittent mandatory ventilation (SIMV) mode with the

Matthew F Gross; Robert M Spear; Bradley M Peterson

2000-01-01

260

Comparison of muon and pion capture ratios in H2-Ar gas mixtures  

NASA Astrophysics Data System (ADS)

The muonic Coulomb capture ratio A(H2,Ar) has been measured in two different H2-Ar gas mixtures using two different methods of evaluation based on the muon transfer from hydrogen. The measured ratios agree with each other, but disagree with the corresponding pionic capture ratio and also with the ratios calculated from muonic and pionic A(He,Ar) and A(He,H2) capture ratios. The large discrepancies might be related to unsolved problems in muon transfer.

Jacot-Guillarmod, R.; Bienz, F.; Boschung, M.; Piller, C.; Schaller, L. A.; Schellenberg, L.; Schneuwly, H.; Reichart, W.

1989-01-01

261

Defect Assessment on Pipe Transporting a Mixture of Natural Gas and Hydrogen  

Microsoft Academic Search

Procedure of defect assessment for steel pipes used for hydrogen or mixture of natural gas and hydrogen is proposed. The hydrogen\\u000a concentration is controlled by a cathodic polarisation method. Fracture toughness for blunt pipe defect such as dent is measured\\u000a on “roman tile specimen”. It can be determined either critical J parameter or critical notch stress intensity factor. Then\\u000a the

Guy Pluvinage

262

Improved gas chromatographic analysis of fatty and resin acid mixtures with special reference to tall oil  

Microsoft Academic Search

and Summary  A gas liquid chromatography system for the analysis of complex mixtures of fatty and resin acids has been developed. On 30–40\\u000a m long, 0.3 mm ID glass capillary columns coated with 1,4-butanediol succinate (BDS) and attaining over 90,000 effective theoretical\\u000a plates, all main fatty and resin acids in wood extractives and various tall oil products can be separated and

B. Holmbom

1977-01-01

263

Multi-scale k-distribution model for gas mixtures in hypersonic nonequilibrium flows  

Microsoft Academic Search

A k-distribution model is presented for gas mixtures in thermodynamic nonequilibrium, containing strongly radiating atomic species N and O together with molecular species of N2, N2+, NO and O2. In the VUV range of the spectrum there is strong absorption of atomic radiation by bands of N2. For this spectral range, a multi-scale model is presented, where RTEs are solved

Ankit Bansal; M. F. Modest; D. A. Levin

2011-01-01

264

Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium  

Microsoft Academic Search

The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared

E. C. Anderson; J. N. Moss

1975-01-01

265

High rate concentration measurement of molecular gas mixtures using a spatial detection technique  

NASA Astrophysics Data System (ADS)

Concentration measurement in molecular gas mixtures using a snapshot spatial imaging technique is reported. The approach consists of measuring the birefringence of the molecular sample when field-free alignment takes place, each molecular component producing a signal with an amplitude depending on the molecular density. The concentration measurement is obtained on a single-shot basis by probing the time-varying birefringence through femtosecond time-resolved optical polarigraphy (FTOP). The relevance of the method is assessed in air.

Loriot, V.; Hertz, E.; Lavorel, B.; Faucher, O.

2010-05-01

266

Thermal explosion in a hot gas mixture with fuel droplets: a two reactant model  

Microsoft Academic Search

We extend previous analyses of thermal explosion in a gas-droplets mixture to permit a more complete description of the chemistry via a single-step two-reactant model of general order, rather than the prior deficient reactant model. A detailed mathematical analysis has been carried out of this new physical model that encompasses oxidizer effects (in both fuel rich and fuel lean situations)

Viatcheslav Bykov; Igor Goldfarb; Vladimir Gol’dshtein; J. Barry Greenberg

2002-01-01

267

Unstructured Adaptive Grid Flow Simulations of Inert and Reactive Gas Mixtures  

Microsoft Academic Search

Unstructured adaptive grid flow simulation is applied to the calculation of high-speed compressible flows of inert and reactive gas mixtures. In the present case, the flowfield is simulated using the 2-D Euler equations, which are discretized in a cell-centered finite volume procedure on unstructured triangular meshes. Interface fluxes are calculated by a Liou flux vector splitting scheme which has been

L. F. Figueira da Silva; João L. F. Azevedo; Heidi Korzenowski

2000-01-01

268

Hot gas ignition temperatures of hydrocarbon fuel vapor-air mixtures  

Microsoft Academic Search

Laminar hot air jets of ¹\\/â to ³\\/â-inch diameter were employed to determine the hot gas ignition temperatures of various combustible vapor-air mixtures. The combustibles were n-hexane, n-octane, n-decane, a hydrocarbon jet fuel (JP-6) and an adipate ester aircraft engine oil (MIL-L-7808). Minimum ignition temperatures occurred at a fuel-air weight ratio of about 0.5 and were not greatly sensitive to

R. J. Cato; J. M. Kuchta

1965-01-01

269

XENON-133 IN CALIFORNIA, NEVADA, AND UTAH FROM THE CHERNOBYL ACCIDENT (JOURNAL VERSION)  

EPA Science Inventory

The accident at the Chernobyl nuclear reactor in the USSR introduced numerous radioactive nuclides into the atmosphere, including the noble gas xenon-133. EPA's Environmental Monitoring Systems Laboratory, Las Vegas, NV, detected xenon-133 from the Chernobyl accident in air sampl...

270

In vivo Mapping of Local Cerebral Blood Flow by Xenon-Enhanced Computed Tomography  

Microsoft Academic Search

A noninvasive technique has been developed to measure and display local cerebral blood flow (LCBF) in vivo. In this procedure, nonradioactive xenon gas is inhaled and the temporal changes in radiographic enhancement produced by the inhalation are measured by sequential computerized tomography. The time-dependent xenon concentrations in various anatomical units in the brain are used to derive both the local

David Gur; Walter F. Good; Sidney K. Wolfson; Howard Yonas; Leonard Shabason

1982-01-01

271

INTEGRAL AND SPECTRAL CHARACTERISTICS OF ATON STATIONARY PLASMA THRUSTER OPERATING ON KRYPTON AND XENON  

Microsoft Academic Search

The integral characteristics of an ATON (1) stationary plasma thruster operating on xenon and krypton are investigated. It is shown that, with krypton, the thrust at the same mass flow rate of the working gas is greater and the efficiency is somewhat lower than those with xenon. An efficiency of ~60% was achieved with krypton for the specific impulse attaining

A. I. Bugrova; A. I. Morozov; A. S. Lipatov; A. M. Bishaev; V. K. Kharchevnikov; M. V. Kozintseva

272

Mixture of Tonks-Girardeau gas and Fermi gas in one-dimensional optical lattices  

SciTech Connect

We study the Bose-Fermi mixture with infinite boson-boson repulsion and finite boson-fermion repulsion. Using a generalized Jordan-Wigner transformation, we show that the system can be mapped to a repulsive Hubbard model and thus can be solved exactly for the case with equal boson and fermion masses. Using the Bethe-ansatz solutions, we investigate the ground-state properties of the mixture system. Our results indicate that the system with commensurate filling n=1 is a charge insulator but still a superfluid with nonvanishing superfluid density. We also briefly discuss the case with unequal boson and fermion masses.

Chen Shu; Cao Junpeng [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Gu Shijian [Department of Physics and Institute of Theoretical Physics, Chinese University of Hong Kong (Hong Kong)

2010-11-15

273

Plasma nitriding using high H2 content gas mixtures for a cavitation erosion resistant steel  

NASA Astrophysics Data System (ADS)

Plasma nitriding using high H2 content gas mixtures in CA-6NM martensitic stainless steel was studied in the present work. Nitriding was performed in H2 + N2 gas mixtures for 5, 10 and 20% N2, in volume, at 773 K (500 °C), during 2 h. Changes in the surface morphology and nitrided layer constitution were characterized by SEM, XRD, roughness analysis, and nanoindentation technique. Cavitation erosion behavior of the nitrided samples was also investigated by means of a 20 kHz ultrasonic vibrator. The study was emphasized for the three first cavitation stages (incubation, acceleration, and maximum erosion rate stage) of the cumulative erosion–time curve. Results indicate that the gas mixture nitrogen content strongly influences the phases' formation and its distribution on the nitrided layer. Better cavitation erosion resistance which was attributed to the finer and more homogeneous distribution of the nitrided layer phases was verified for samples treated at 5% N2. Otherwise, worse cavitation erosion behavior for samples nitrided at 20% N2 is supposed to be due to the formation of multiphase compound layer constituted by Fe4N + Fe2–3N + CrN, which can infer residual stress in treated surface.

Allenstein, A. N.; Lepienski, C. M.; Buschinelli, A. J. A.; Brunatto, S. F.

2013-07-01

274

Non-equilibrium thermodynamics and kinetic theory of gas mixtures in the presence of interfaces.  

PubMed

A broad range of the boundary value problems of the kinetic theory of gases and gas mixtures is considered based on kinetic theory and non-equilibrium thermodynamics. The interrelation of the kinetic theory and non-equilibrium thermodynamics is discussed. The balance equations at the interface are obtained for the case of the boundary layers with peculiar properties. Procedures for deriving the boundary conditions for slightly rarefied gas mixtures are outlined. The problems of calculating slip coefficients are discussed. The specificity of the kinetic effects in the boundary conditions is shown. A set of general relations related to gas mixture flows in capillaries is deduced. The possibility of non-equilibrium kinetic effects in the form of a paradoxical distribution of non-equilibrium temperature is shown. Methods of non-equilibrium thermodynamics are used to obtain the phenomenological equations describing the thermophoresis and diffusiophoresis of particles and cross phenomena. The growth and evaporation of droplets is considered based on kinetic theory and non-equilibrium thermodynamics. PMID:12144096

Roldughi, V I; Zhdanov, V M

2002-06-10

275

Optical absorption method of natural gas component analysis in real time. Part II. Analysis of mixtures of arbitrary composition  

NASA Astrophysics Data System (ADS)

The present paper continues the presentation of the results of studies started in [1]. The referred paper reports the development of the optical method for component analysis of natural gas mixtures with different compositions, allowing conducting measurements in real time. The method is based on the measurement of the absorption coefficients for the analyzed gas mixture at several wavelengths within the infrared region of the spectrum (7-14 ?m), with the selected number and values of wavelengths depending on the category of the gas mixture. The resulting accuracy of the determination of the main components of gas mixtures including methane, ethane, propane, butane, pentane and carbon dioxide is sufficient for the use of the developed method for the monitoring of the component composition of natural gas in pipelines.

Kireev, S. V.; Podolyako, E. M.; Simanovsky, I. G.; Shnyrev, S. L.

2012-10-01

276

Preliminary Results for Capture of Negative Muons and Antiprotons by Noble-Gas Atoms  

Microsoft Academic Search

Cross sections for capture of negative muons (mu-) and antiprotons ({bar p}) by helium, neon, argon, krypton, and xenon atoms (incomplete for the two heaviest noble-gas atoms) are calculated using the fermion molecular dynamics (FMD) method. These cross sections are used to estimate the capture ratios in mixtures, but these ratios are not precise since the total energy-loss cross sections

James S. Cohen

2001-01-01

277

Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures  

SciTech Connect

A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

Aines, Roger D. (Livermore, CA); Bourcier, William L. (Livermore, CA)

2010-11-09

278

ISOTOPIC COMPOSITION OF PRIMORDIAL XENON  

Microsoft Academic Search

A large excess of Xe¹²⁹ and secondary anomalous abundances for ; many of the other isotopes of xenon were previously reported for the meteorite, ; Richardton. Similar secondary anomalies in xenon are reported for the meteorite ; Murray. For every isotope other than Xe¹²⁹, the ratio of the Murray ; percent abundance to the Richardton percent abundance was the same

J. Reynolds

1960-01-01

279

Spin relaxation in hyperpolarized krypton-83 and xenon-129  

NASA Astrophysics Data System (ADS)

The potential medical application of hyperpolarized (hp) krypton-83 (spin S = 9/2) [1] make a better insight into the NMR relaxation behavior of this isotope desirable, in particular since the relaxation limits the observed signal intensity but also provides a source for MRI contrast. The quadrupolar relaxation of krypton-83 is shown to be highly dependent on temperature, optical pumping gas mixture, the nature of surrounding surfaces and the applied magnetic field strength [2, 3]. The relaxation is mainly caused by quadrupolar interactions during brief surface adsorption periods of the krypton atoms onto the surrounding container walls. In contrast to xenon-129, interactions with paramagnetic impurities in the surface or with gas phase oxygen are not significant. 1) Pavlovskaya, et al. Proc. Natl. Acad. Sci. U.S.A.,2005. 102: 18275-18279; 2) Cleveland, Z.I., et al. J. Chem. Phys., 2006. 124(4) 044311; 3) Stupic, K.F et al. Solid State Nucl. Magn. Reson., 2006. 29: 79-84.

Meersmann, Thomas; Cleveland, Zackary; Stupic, Karl; Pavlovskaya, Galina

2007-03-01

280

Determination of time-course change rate for arterial xenon using the time course of tissue xenon concentration in xenon-enhanced computed tomography  

SciTech Connect

In calculating tissue blood flow (TBF) according to the Fick principle, time-course information on arterial tracer concentration is indispensable and has a considerable influence on the accuracy of calculated TBF. In TBF measurement by xenon-enhanced computed tomography (Xe-CT), nonradioactive xenon gas is administered by inhalation as a tracer, and end-tidal xenon is used as a substitute for arterial xenon. There has been the assumption that the time-course change rate for end-tidal xenon concentration (Ke) and that for arterial xenon concentration (Ka) are substantially equal. Respiratory gas sampling is noninvasive to the patient and Ke can be easily measured by exponential curve fitting to end-tidal xenon concentrations. However, it is pointed out that there would be a large difference between Ke and Ka in many cases. The purpose of this work was to develop a method of determining the Ka value using the time course of tissue xenon concentration in Xe-CT. The authors incorporated Ka into the Kety autoradiographic equation as a parameter to be solved, and developed a method of least-squares to obtain the solution for Ka from the time-course changes in xenon concentration in the tissue. The authors applied this method of least-squares to the data from Xe-CT abdominal studies performed on 17 patients; the solution for Ka was found pixel by pixel in the spleen, and its Ka map was created for each patient. On the one hand, the authors obtained the average value of the Ka map of the spleen as the calculated Ka (Ka{sub calc}) for each patient. On the other hand, the authors measured Ka (Ka{sub meas}) using the time-course changes in CT enhancement in the abdominal aorta for each patient. There was a good correlation between Ka{sub calc} and Ka{sub meas} (r=0.966, P<0.0001), and these two Ka values were close to each other (Ka{sub calc}=0.935xKa{sub meas}+0.089). This demonstrates that Ka{sub calc} would be close to the true Ka value. Accuracy of TBF by Xe-CT can be improved with use of the average value of the Ka map of an organ like the spleen that has a single blood supply (only arterial inflow)

Sase, Shigeru; Takahashi, Hideaki; Ikeda, Hiroki; Kobayashi, Minoru; Matsumoto, Nobuyuki; Suzuki, Michihiro [Anzai Medical Co., Ltd., 3-9-15 Nishi-Shinagawa, Shinagawa-ku, Tokyo 141-0033 (Japan); Department of Internal Medicine, Division of Gastroenterology and Hepatology, School of Medicine, St. Marianna University, 2-16-1 Miyamae-ku, Sugao, Kawasaki 216-5811 (Japan)

2008-06-15

281

Adiabatic temperature changes of magma-gas mixtures during ascent and eruption  

USGS Publications Warehouse

Most quantitative studies of flow dynamics in eruptive conduits during volcanic eruptions use a simplified energy equation that ignores either temperature changes, or the thermal effects of gas exsolution. In this paper we assess the effects of those simplifications by analyzing the influence of equilibrium gas exsolution and expansion on final temperatures, velocities, and liquid viscosities of magma-gas mixtures during adiabatic decompression. For a given initial pressure (p1), temperature (T1) and melt composition, the final temperature (Tf) and velocity (Umax) will vary depending on the degree to which friction and other irreversible processes reduce mechanical energy within the conduit. The final conditions range between two thermodynamic end members: (1) Constant enthalpy (dh=0), in which Tf is maximal and no energy goes into lifting or acceleration; and (2) constant entropy (ds=0), in which Tf is minimal and maximum energy goes into lifting and acceleration. For ds=0, T1=900 ??C and p1=200 MPa, a water-saturated albitic melt cools by ???200 ??C during decompression, but only about 250 ??C of this temperature decrease can be attributed to the energy of gas exsolution per se: The remainder results from expansion of gas that has already exsolved. For the same T1 and p1, and dh=0, Tf is 10-15 ??C hotter than T1 but is about 10-25 ??C cooler than Tf in similar calculations that ignore the energy of gas exsolution. For ds=0, p1=200 MPa and T1= 9,000 ??C, assuming that all the enthalpy change of decompression goes into kinetic energy, a water-saturated albitic mixture can theoretically accelerate to ???800 m/s. Similar calculations that ignore gas exsolution (but take into account gas expansion) give velocities about 10-15% higher. For the same T1, p1 = 200 MPa, and ds = 0, the cooling associated with gas expansion and exsolution increases final melt viscosity more than 2.5 orders of magnitude. For dh = 0, isenthalpic heating decreases final melt viscosity by about 0.7 orders of magnitude. Thermal effects of gas exsolution are responsible for less than 10% of these viscosity changes. Isenthalpic heating could significantly reduce flow resistance in eruptive conduits if heat generation were concentrated along conduit walls, where shearing is greatest. Isentropic cooling could enhance clast fragmentation in near-surface vents in cases where extremely rapid pressure drops reduce gas temperatures and chill the margins of expanding pyroclasts.

Mastin, L. G.; Ghiorso, M. S.

2001-01-01

282

Thermodynamic stability, spectroscopic identification, and gas storage capacity of CO2-CH4-N2 mixture gas hydrates: implications for landfill gas hydrates.  

PubMed

Landfill gas (LFG), which is primarily composed of CH(4), CO(2), and N(2), is produced from the anaerobic digestion of organic materials. To investigate the feasibility of the storage and transportation of LFG via the formation of hydrate, we observed the phase equilibrium behavior of CO(2)-CH(4)-N(2) mixture hydrates. When the specific molar ratio of CO(2)/CH(4) was 40/55, the equilibrium dissociation pressures were gradually shifted to higher pressures and lower temperatures as the mole fraction of N(2) increased. X-ray diffraction revealed that the CO(2)-CH(4)-N(2) mixture hydrate prepared from the CO(2)/CH(4)/N(2) (40/55/5) gas mixture formed a structure I clathrate hydrate. A combination of Raman and solid-state (13)C NMR measurements provided detailed information regarding the cage occupancy of gas molecules trapped in the hydrate frameworks. The gas storage capacity of LFG hydrates was estimated from the experimental results for the hydrate formations under two-phase equilibrium conditions. We also confirmed that trace amounts of nonmethane organic compounds do not affect the cage occupancy of gas molecules or the thermodynamic stability of LFG hydrates. PMID:22380606

Lee, Hyeong-Hoon; Ahn, Sook-Hyun; Nam, Byong-Uk; Kim, Byeong-Soo; Lee, Gang-Woo; Moon, Donghyun; Shin, Hyung Joon; Han, Kyu Won; Yoon, Ji-Ho

2012-03-13

283

Heat Transfer in a Gas Mixture Between Two Parallel Plates: Finite- difference Analysis of the Boltzmann Equation.  

National Technical Information Service (NTIS)

The problem of heat transfer and temperature distribution in a binary mixture of rarefied gases between two parallel plates with different temperatures is investigated on the basis of kinetic theory. Under the assumption that the gas molecules are hard sp...

S. Kosuge K. Aoki S. Takata

2000-01-01

284

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

Microsoft Academic Search

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

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

2000-01-01

285

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

Microsoft Academic Search

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

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

2000-01-01

286

The krypton and xenon markets up to the year 2000  

NASA Astrophysics Data System (ADS)

Krypton and xenon are rare gases which are found in air in concentrations of about 1.14 and 0.087 ppm, respectively. They are produced in specially equipped, very large air separation units by adding a special raw gas extraction unit. Then this raw gas is purified and the krypton and xenon are separated by cryogenic methods. These rare gases are used in the lamp industry, for medical applications and in laser and research applications. The market for krypton and xenon is growing. The production capacity for these gases is limited and this results in a cyclic behavior of availability and market price. In the next few years, 10-20 million liters of krypton and one to two million liters of xenon will become available on the market due to new investments in the USA, South Africa and the AGA AB joint venture in the USSR. The total world production capacity of krypton and xenon will increase to 60-80 million liters. To influence the availability of these gases it is important to have close partnership between user and producer, which will realize bright and unorthodox ideas for the supply and use of these rare gases. Marketing Manager of AGA AB

Hammarlund, Nils

1992-05-01

287

Transport coefficients in nonequilibrium gas-mixture flows with electronic excitation.  

PubMed

In the present paper, a one-temperature model of transport properties in chemically nonequilibrium neutral gas-mixture flows with electronic excitation is developed. The closed set of governing equations for the macroscopic parameters taking into account electronic degrees of freedom of both molecules and atoms is derived using the generalized Chapman-Enskog method. The transport algorithms for the calculation of the thermal-conductivity, diffusion, and viscosity coefficients are proposed. The developed theoretical model is applied for the calculation of the transport coefficients in the electronically excited N/N(2) mixture. The specific heats and transport coefficients are calculated in the temperature range 50-50,000 K. Two sets of data for the collision integrals are applied for the calculations. An important contribution of the excited electronic states to the heat transfer is shown. The Prandtl number of atomic species is found to be substantially nonconstant. PMID:19905461

Kustova, E V; Puzyreva, L A

2009-10-28

288

CO2 capture from simulated fuel gas mixtures using semiclathrate hydrates formed by quaternary ammonium salts.  

PubMed

In order to investigate the feasibility of semiclathrate hydrate-based precombustion CO2 capture, thermodynamic, kinetic, and spectroscopic studies were undertaken on the semiclathrate hydrates formed from a fuel gas mixture of H2 (60%) + CO2 (40%) in the presence of quaternary ammonium salts (QASs) such as tetra-n-butylammonium bromide (TBAB) and fluoride (TBAF). The inclusion of QASs demonstrated significantly stabilized hydrate dissociation conditions. This effect was greater for TBAF than TBAB. However, due to the presence of dodecahedral cages that are partially filled with water molecules, TBAF showed a relatively lower gas uptake than TBAB. From the stability condition measurements and compositional analyses, it was found that with only one step of semiclathrate hydrate formation with the fuel gas mixture from the IGCC plants, 95% CO2 can be enriched in the semiclathrate hydrate phase at room temperature. The enclathration of both CO2 and H2 in the cages of the QAS semiclathrate hydrates and the structural transition that results from the inclusion of QASs were confirmed through Raman and (1)H NMR measurements. The experimental results obtained in this study provide the physicochemical background required for understanding selective partitioning and distributions of guest gases in the QAS semiclathrate hydrates and for investigating the feasibility of a semiclathrate hydrate-based precombustion CO2 capture process. PMID:23718261

Park, Sungwon; Lee, Seungmin; Lee, Youngjun; Seo, Yongwon

2013-06-11

289

Probing gas motions in the intra-cluster medium: a mixture model approach  

NASA Astrophysics Data System (ADS)

Upcoming high spectral resolution telescopes, particularly Astro-H, are expected to finally deliver firm quantitative constraints on turbulence in the intra-cluster medium (ICM). We develop a new spectral analysis technique which exploits not just the line width but the entire line shape, and show how the excellent spectral resolution of Astro-H can overcome its relatively poor spatial resolution in making detailed inferences about the velocity field. The spectrum is decomposed into distinct components, which can be quantitatively analysed using Gaussian mixture models. For instance, bulk flows and sloshing produce components with offset means, while partial volume-filling turbulence from the active galactic nucleus (AGN) or galaxy stirring leads to components with different widths. The offset between components allows us to measure gas bulk motions and separate them from small-scale turbulence, while component fractions and widths constrain the emission weighted volume and turbulent energy density in each component. We apply mixture modelling to a series of analytic toy models as well as numerical simulations of clusters with cold fronts and AGN feedback, respectively. From Markov chain Monte Carlo and Fisher's matrix estimates which include line blending and continuum contamination, we show that the mixture parameters can be accurately constrained with Astro-H spectra: at an ˜10 per cent level when components differ significantly in width, and an ˜1 per cent level when they differ significantly in the mean value. We also study error scalings and use information criteria to determine when a mixture model is preferred. Mixture modelling of spectra is a powerful technique which is potentially applicable to other astrophysical scenarios.

Shang, Cien; Oh, S. Peng

2012-11-01

290

Ethane and Xenon mixing: density functional theory (DFT) simulations and experiments on Sandia's Z machine  

NASA Astrophysics Data System (ADS)

The combination of ethane and xenon is one of the simplest binary mixtures in which bond breaking is expected to play a role under shock conditions. At cryogenic conditions, xenon is often understood to mix with alkanes such as Ethane as if it were also an alkane, but this model is expected to break down at higher temperatures and pressures. To investigate the breakdown, we have performed density functional theory (DFT) calculations on several xenon/ethane mixtures. Additionally, we have performed shock compression experiments on Xenon-Ethane using the Sandia Z - accelerator. The DFT and experimental results are compared to hydrodynamic simulations using different mixing models in the equation of state. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of the Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Magyar, Rudolph; Root, Seth; Mattsson, Thomas; Cochrane, Kyle

2012-02-01

291

Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface  

SciTech Connect

Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry's Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

Ritter, J.A.

1992-01-01

292

Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface  

SciTech Connect

Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry`s Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

Ritter, J.A.

1992-10-01

293

Comparison of muon and pion capture ratios in H/sub 2/-Ar gas mixtures  

SciTech Connect

The muonic Coulomb capture ratio A(H/sub 2/,Ar) has been measured in two different H/sub 2/-Ar gas mixtures using two different methods of evaluation based on the muon transfer from hydrogen. The measured ratios agree with each other, but disagree with the corresponding pionic capture ratio and also with the ratios calculated from muonic and pionic A(He,Ar) and A(He,H/sub 2/) capture ratios. The large discrepancies might be related to unsolved problems in muon transfer.

Jacot-Guillarmod, R.; Bienz, F.; Boschung, M.; Piller, C.; Schaller, L.A.; Schellenberg, L.; Schneuwly, H.; Reichart, W.

1989-01-01

294

An ES-BGK model for a gas mixture with bimolecular chemical reaction  

NASA Astrophysics Data System (ADS)

A relaxation-time-approximation of a Boltzmann kinetic model for a slow bimolecular chemical reaction in a collision dominated gas mixture is presented. The dominant mechanical collision operator, approximated by an ellipsoidal BGK operator recently introduced in the literature, is coupled to a kinetic relaxation model enforcing chemical equilibrium. The hydrodynamic limit up to the fluid-dynamic reactive Navier-Stokes equations are worked out by a Chapman-Enskog asymptotic procedure, emphasizing reactive effects in the resulting reaction-diffusion transport equations.

Groppi, M.; Spiga, G.

2012-11-01

295

Property value estimation for inhaled therapeutic binary gas mixtures: He, Xe, N2O, and N2 with O2  

PubMed Central

Background The property values of therapeutic gas mixtures are important in designing devices, defining delivery parameters, and in understanding the therapeutic effects. In the medical related literature the vast majority of articles related to gas mixtures report property values only for the pure substances or estimates based on concentration weighted averages. However, if the molecular size or structures of the component gases are very different a more accurate estimate should be considered. Findings In this paper estimates based on kinetic theory are provided of density, viscosity, mean free path, thermal conductivity, specific heat at constant pressure, and diffusivity over a range of concentrations of He-O2, Xe-O2, N2O-O2 and N2-O2 mixtures at room (or normal) and body temperature, 20 and 37°C, respectively and at atmospheric pressure. Conclusions Property value estimations have been provided for therapeutic gas mixtures and compared to experimental values obtained from the literature where possible.

2011-01-01

296

Irradiated Xenon Isotopic Ratio Measurement for Failed Fuel Detection and Location in Fast Reactor  

NASA Astrophysics Data System (ADS)

The accuracy of xenon isotopic ratio burn-up calculations used for failed fuel identification was evaluated by an irradiation test of xenon tag gas samples in the Joyo test reactor. The experiment was carried out using pressurized steel capsules containing unique blend ratios of stable xenon tag gases in an on-line creep rupture experiment in Joyo. The tag gas samples were irradiated to total neutron fluences of 1.6 to 4.8 × 1026 n/m2. Laser resonance ionization mass spectrometry was used to analyze the cover gas containing released tag gas diluted to isotopic ratios of 100 to 102 ppb. The isotopic ratios of xenon tag gases after irradiation were calculated using the ORIGEN2 code. The neutron cross sections of xenon nuclides were based on the JENDL-3.3 library. These cross sections were collapsed into one group using the neutron spectra of Joyo. The comparison of measured and calculated xenon isotopic ratios provided C/E values that ranged from 0.92 to 1.10. The differences between calculation and measurement were considered to be mainly due to the measurement errors and the xenon nuclide cross section uncertainties.

Ito, Chikara; Iguchi, Tetsuo; Harano, Hideki

2009-08-01

297

[Impact of hypoxic gas mixtures on embryogenesis of the Japanese quail].  

PubMed

Avian embryogenesis is of great interest to investigators, as the germ developing outside mother's body, is capable to react briskly to any alteration in the outer world. The paper present experimental evidence of the impact of oxygen with physical and chemical properties modified by short-cycle no-heating adsorption (SNA) in a hypoxic gas mixture (10% O2) on the early embryogenesis of the Japanese quail. Low concentrations of oxygen are known to be a dramatically disturbing factor for embryo's morphology. It was demonstrated experimentally that four days before incubation bird are highly sensitive to oxygen deficiency which is responsible for developmental abnormalities. The use of SNA oxygen reduced the frequency of pathologies in the Japanese quail germs as compared with their controls incubated in gas environment containing medical oxygen generated by low-temperature rectification. PMID:18672516

Soldatov, P E; Gur'eva, T S; Dadasheva, O A; Smirnov, I A; Smolenskaia, T S; Mednikova, E I; Lysenko, L A

298

Efficiency and pressure recovery in hydraulic jet pumping of two-phase gas/liquid mixtures  

SciTech Connect

Hydraulic jet pumping of gas/liquid mixtures was studied experimentally, and a mathematical model is proposed to extend the standard single-phase model for predicting efficiency and pressure recovery to suction fluids with gas/liquid ratios up to 2.200 scf/STB. The experimental program comprises 616 low-pressure tests in a plastic model pump designed for flow visualization and measurement of pressure profile along the throat and diffuser, and 373 high-pressure tests on a stock pump. For the high-pressure tests, power fluid was supplied at 200 to 3,000 psi and at 200 to 860 B/D; air was supplied from 0 to 185 Mscf/D. Discharge pressures ranged from 800 to 2,000 psi.

Jlao, B.; Blals, R.N.; Schmidt, Z. (Tulsa Univ., OK (USA))

1990-11-01

299

Xenon and krypton isotopes in extraterrestrial regolith soils and in the solar wind  

Microsoft Academic Search

Isotopic distributions of pure solar-wind xenon and krypton are derived from an extensive data base of xenon and krypton compositions evolved from lunar and meteoritic regolith samples by acid-etching or combustion-pyrolysis experiments in several different laboratories. Regolith Xe and Kr are nonuniform mixtures of primary solar-wind components with others arising in situ from cosmic-ray spallation, neutron-capture in iodine and bromine,

R. O. Pepin; R. H. Becker; P. E. Rider

1995-01-01

300

Thermophysical properties of neon, argon, krypton, and xenon  

Microsoft Academic Search

Addressing the thermophysical properties of the rare gas elements - neon, argon, krypton, and xenon - this thorough work offers new research and uniform data. Tables cover properties in these elements crystalline, liquid, and gaseous states, spanning a temperature range of 0-1300 K, and for pressures up to 100 MPa. This volume contains thermodynamic properties in the solid phase and

V. A. Rabinovich; A. A. Vasserman; V. I. Nedostup; L. S. Veksler

1987-01-01

301

Liquid xenon scintillation calorimetry and Xe optical properties  

Microsoft Academic Search

The optical properties of liquid xenon (LXe) in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be

A. Baldini; C. Bemporad; F. Cei; T. Doke; M. Grassi; T. Haruyama; S. Mihara; T. Mori; D. Nicolo; H. Nishiguchi; W. Ootani; K. Ozone; A. Papa; R. Pazzi; R. Sawada; F. Sergiampietri; G. Signorelli; S. Suzuki; K. Terasawa

2006-01-01

302

Sound Absorption and Dispersion along the Critical Isochore in Xenon  

Microsoft Academic Search

Ultrasonic and Brillouin absorption and velocity data along the critical isochore in xenon are reinterpreted in terms of modified theoretical expressions derived within the framework of the Fixman-Mistura theory. The new expressions mainly arise from avoiding the unjustified assumption of small dispersion near a liquid-gas critical point. Numerical analysis of the data shows quite satisfactory agreement between theory and experiment

Don Eden; Carl W. Garland; Jan Thoen

1972-01-01

303

Environmental application of stable xenon and radioxenonmonitoring  

SciTech Connect

Characterization of transuranic waste is needed to makedecisions about waste site remediation. Soil-gas sampling for xenonisotopes can be used to define the locations of spent fuel andtransuranic wastes. Radioxenon in the subsurface is characteristic oftransuranic waste and can be measured with extreme sensitivity usinglarge-volume soilgas samples. Measurements at the Hanford Site showed133Xe and 135Xe levels indicative of 240Pu spontaneous fission. Stablexenon isotopic ratios from fission are distinct from atmospheric xenonbackground. Neutron capture by 135Xe produces an excess of 136Xe inreactor-produced xenon providing a means of distinguishing spent fuelfrom separated transuranic materials.

Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre,Justin I.; Waichler, Scott R.; Milbrath, Brian D.; Cooper, Matt; Kennedy,B. Mack

2006-09-05

304

Solubilities of krypton and xenon in dichlorodifluoromethane  

SciTech Connect

The solubility behavior of krypton and xenon in dichlorodifluoromethane was investigated for the Consolidated Fuel Reprocessing Program (CFRP) in support of the fluorocarbon absorption process. The solubility data derived from solute radioisotopes had uncertainties of approx. 0.1%. Values for Henry's law constants were initially determined under equilibrium conditions at infinite solute dilution. Based on these results, the study was extended to finite solute concentrations. Nonidealities in the two binary systems were expressed as gas phase fugacity coefficients for each solute at 10/sup 0/ intervals over the range -30 to +50/sup 0/C. 22 references, 4 figures, 2 tables.

Shaffer, J.H.; Shockley, W.E.; Greene, C.W.

1984-07-01

305

Isolation of individual hydrocarbons from the unresolved complex hydrocarbon mixture of a biodegraded crude oil using preparative capillary gas chromatography  

Microsoft Academic Search

We describe the isolation, using preparative capillary gas chromatography, of hydrocarbon fractions from an unresolved complex mixture (UCM) of hydrocarbons isolated from a biodegraded crude oil. Some of the individual hydrocarbons in these fractions were then resolved by gas chromatography (GC) and identified using GC–mass spectrometry (GC–MS). The mass spectra contained distinct molecular ions. As a preliminary example, after preparative

P. A. Sutton; C. A. Lewis; S. J. Rowland

2005-01-01

306

Pressure and temperature dependence of gas amplification gains in R134a-isobutane-SF6 mixtures for RPCs  

NASA Astrophysics Data System (ADS)

The PHENIX first level muon trigger upgrade will include dedicated muon tracking spectrometers based on resistive plate chamber (RPC) technology. We have studied the pressure and temperature dependence of gas amplificiation in typical gas mixtures expected for the RPC application in PHENIX.

Wood, John

2007-10-01

307

Calculation of single adsorption isotherms from gravimetrically measured binary gas mixture adsorption isotherms on activated carbon at high pressures  

Microsoft Academic Search

A method is developed for the calculation of single-component adsorption isotherms from gravimetrically measured binary gas mixture adsorption isotherms at high pressures, at two temperatures and for different mole fractions of the gas phase. The adsorption of nitrogen\\/methane on active carbon Norit R1 is taken as an experimental example.

P. Braeuer; M. Salem; P. Harting; K. Quitzsch

1997-01-01

308

Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons  

SciTech Connect

A Simplified augmented BACK equation of state has been developed for the description of gas-liquid-liquid equilibria in mixtures of water, light, gases, and hydrocarbons. The simplification facilitates application of the equation. In the Augmented BACK equation the polar pressure of water is the difference between two long expressions. One of these is the 26-term BACK equation written for the non-polar core of the water molecule, and the other is the Keeman steam table equation containing 55 equation constants. The complexity is compounded when derivation is made of the equation for fugacity, enthalpy and other thermodynamic quantities, leading to working equations that contain more than one hundred terms. The complexity presents a barrier to useful application. The new simplified equation has been extensively tested. Calculations with the Augmented BACK equation (before simplification) are described with example mixtures. Included are mixtures of water + light gases, water + hydrocarbons, and polar substances in general. Phase equilibrium, density, and enthalpy are calculated. 3 figs.

Chao, K.C.

1989-01-01

309

Solubilized xenon 133 lung scintigraphy  

SciTech Connect

Lung scanning using solubilized xenon 133 can provide important information concerning both pulmonary perfusion and ventilation. This technique proved valuable in establishing the diagnosis of congenital lobar emphysema in a 7-month-old baby.

Oates, E.; Sarno, R.C.

1988-11-01

310

Optical pumping and xenon NMR.  

National Technical Information Service (NTIS)

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness an...

M. D. Raftery

1991-01-01

311

XENON TETRAFLUORIDE: HEAT OF FORMATION  

Microsoft Academic Search

Calorimetric measurements of the heat of reaction of xenon tetrafluoride ; with aqueous iodide solution give -- 60 kilocalories per mole for the standard ; heat of formation, or an average thermochemical bond energy of about 31 ; kilocalories. (auth);

S. R. Gunn; S. M. Williamson

1963-01-01

312

Optimization of the microstrip gas counter  

NASA Astrophysics Data System (ADS)

A study has been made to optimize the characteristics of the microstrip gas counter for use as a tracker at the LHC. In this framework we found that two of the most important design parameters of the detector are given by the choice of the counter gas and the width of the gas gap. In this report we deduce, using measurements done with a UV laser and a particle beam, two most suited mixtures which consist of xenon, di-methyl-ether and CO2. We also derive the optimum width of the gas gap. With these results an efficient event tagging will be possible at the LHC bunch frequency.

Geijsberts, M. H. J.; Hartjes, F. G.; Pannekoek, J. G.; Schmitz, J.; Udo, F.

1992-05-01

313

Modeling Xenon Purification Systems in a Laser Inertial Fusion Engine  

NASA Astrophysics Data System (ADS)

A Laser Inertial Fusion Engine (LIFE) is a proposed method to employ fusion energy to produce electricity for consumers. However, before it can be built and used as such, each aspect of a LIFE power plant must first be meticulously planned. We are in the process of developing and perfecting models for an exhaust processing and fuel recovery system. Such a system is especially essential because it must be able to recapture and purify expensive materials involved in the reaction so they may be reused. One such material is xenon, which is to be used as an intervention gas in the target chamber. Using Aspen HYSYS, we have modeled several subsystems for exhaust processing, including a subsystem for xenon recovery and purification. After removing hydrogen isotopes using lithium bubblers, we propose to use cryogenic distillation to purify the xenon from remaining contaminants. Aspen HYSYS allows us to analyze predicted flow rates, temperatures, pressures, and compositions within almost all areas of the xenon purification system. Through use of Aspen models, we hope to establish that we can use xenon in LIFE efficiently and in a practical manner.

Hopkins, Ann; Gentile, Charles

2011-11-01

314

Hugoniot measurements of double-shocked precompressed dense xenon plasmas.  

PubMed

The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ?6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures. PMID:23368058

Zheng, J; Chen, Q F; Gu, Y J; Chen, Z Y

2012-12-12

315

Hugoniot measurements of double-shocked precompressed dense xenon plasmas  

NASA Astrophysics Data System (ADS)

The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ˜6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

Zheng, J.; Chen, Q. F.; Gu, Y. J.; Chen, Z. Y.

2012-12-01

316

Imaging local cerebral blood flow by Xenon-enhanced computed tomography — Technical optimization procedures  

Microsoft Academic Search

Methods are described for non-invasive, computer-assisted serial scanning throghout the human brain during eight minutes of inhalation of 27%–30% Xenon gas in order to measure local cerebral blood flow (LCBF). Optimized Xenonenhanced computed tomography (XeCT) was achieved by 5-second scanning at one-minute intervals utilizing a state-of-the-art CT scanner and rapid delivery of Xenon gas via a face mask. Values for

J. S. Meyer; T. Shinohara; A. Imai; M. Kobari; F. Sakai; T. Hata; W. T. Oravez; G. M. Timpe; T. Deville; E. Solomon

1988-01-01

317

The Fate and Environmental Consequences of Reduced gas Mixtures Resulting from Magmatic Intrusion into Carbonaceous Rocks  

NASA Astrophysics Data System (ADS)

Recent developments on the impacts of Large Igneous Provinces on climate changes and extinction rates emphasize the fundamental role of country rocks in gas emissions. Contact metamorphism of country rocks intruded by sills and dikes of mafic melts can be particularly important due to their long exposure to high temperatures. When the host rocks are composed of carbonates, sulphates, salts, or organic-compounds such as bituminous shales or coals, their heating can inject into the atmosphere a quantity of volatiles that greatly exceeds the amount delivered by purely magmatic degassing. We focus here on the interaction between magma and carbonaceous rocks. Recent studies have estimated the gas released by contact metamorphism of bituminous shales in the Karoo Province; we calculate the composition of the volcanic gases which results on this interaction, taking into account the magmatic contribution too. We then present an evaluation of the fate of such gases during their diffusion in the atmosphere. The modelling of the composition of the modified volcanic gases is based on gas-melt thermodynamic calculations that take into account S-H-O-C gaseous species at temperatures and pressures in equilibrium with basaltic liquids. We simulate the incorporation into the gas-melt system of organic compounds as CH or CH2, depending on the maturity of the carbonaceous rocks (coal or oil). Addition of C and H has a dramatic effect on the amount and the redox state of the gas in equilibrium with the basalt. With the incorporation of only 0.2 wt% CH, the gas composition changes from CO2-H2O dominated (typical of basaltic gases on Earth), to CO-H2 dominated (a strongly reduced mixture, which resembles Martian volcanic gases). Addition of more than 0.2 wt% CH can trigger graphite saturation, such as reported in few locations where carbonaceous rocks have been ingested by basalts. In the famous Disko Island location, for example, we calculate that an incorporation of 1 wt% CH led to saturation in metal iron. These "modified" volcanic gases are injected into the atmosphere at a rate directly proportional to the eruption rates and then disseminated. Using a 3D atmospheric algorithm coupling convective dynamics and chemistry, we model the expansion of the gas at a continental scale. Our simulations show that, at reasonable gas emission rates, no significant oxidation of CO occurs because the OH-radical concentration is strongly reduced due to the large concentration of CO and H2. This allows the gas to propagate faraway from the emission centre. The lateral propagation of the gas is significant at the scale of a continent within 2 weeks, which might reveal a new mechanism for mass extinctions.

Iacono-Marziano, Giada; Marecal, Virginie; Pirre, Michel; Arndt, Nicolas; Ganino, Clément; Gaillard, Fabrice

2010-05-01

318

Development of a xenon detector for treaty verification. Final report  

SciTech Connect

The project objective was to determine the feasibility of the gas proportional scintillator detector (GPSD) technology to sensitively and selectively detect the decay products of the metastable xenon isotopes as a means of treaty verification for the CTBT. During the course of the project, the investigation involved both computer simulations and laboratory measurements with a GPSD. During the fourth quarter the authors have further investigated the dedicated GPSD response to x-rays and conversion electrons from {sup 109}Cd and {sup 57}Co radioactive sources, comparing simulated and experimental results. The response of a customized high pressure GPSC was also simulated to the higher energy conversion electrons from xenon radioisotopes. An alternative hybrid detector system is proposed showing excellent prospects for xenon radioisotope detection.

NONE

1998-07-21

319

Effect of xenon on the excited States of phototropic receptor flavin in corn seedlings.  

PubMed

The chemically inert, water-soluble heavy atom gas, xenon, at millimolar concentrations specifically quenches the triplet excited state of flavin in solution without quenching the flavin singlet excited state. The preferential quenching of the flavin triplet over the singlet excited state by Xe has been established by showing that the flavin triplet-sensitized photooxidation of NADH is inhibited while the fluorescence intensity and lifetime of flavin are not affected by Xe.The phototropic response of corn seedlings in an atmosphere of 90% Xe and 10% O(2) was compared with that in the 90% N(2) plus 10% O(2) mixture. No significant inhibition of phototropism and geotropism by Xe was observed, suggesting that a flavin singlet state is more likely involved than the triplet state in the primary photoprocess of phototropism in corn. PMID:16661808

Vierstra, R D; Poff, K L

1981-05-01

320

Effect of Xenon on the Excited States of Phototropic Receptor Flavin in Corn Seedlings 1  

PubMed Central

The chemically inert, water-soluble heavy atom gas, xenon, at millimolar concentrations specifically quenches the triplet excited state of flavin in solution without quenching the flavin singlet excited state. The preferential quenching of the flavin triplet over the singlet excited state by Xe has been established by showing that the flavin triplet-sensitized photooxidation of NADH is inhibited while the fluorescence intensity and lifetime of flavin are not affected by Xe. The phototropic response of corn seedlings in an atmosphere of 90% Xe and 10% O2 was compared with that in the 90% N2 plus 10% O2 mixture. No significant inhibition of phototropism and geotropism by Xe was observed, suggesting that a flavin singlet state is more likely involved than the triplet state in the primary photoprocess of phototropism in corn.

Vierstra, Richard D.; Poff, Kenneth L.; Walker, Edward B.; Song, Pill-Soon

1981-01-01

321

Improving Spectroscopic Performance of a Coplanar-Anode High-Pressure Xenon Gamma-Ray Spectrometer  

SciTech Connect

High-pressure xenon (HPXe) gas is a desirable radiation detection medium for homeland security applications because of its good inherent room-temperature energy resolution, potential for large, efficient devices, and stability over a broad temperature range. Past work in HPXe has produced large-diameter gridded ionization chambers with energy resolution at 662 keV between 3.5 and 4% FWHM. However, one major limitation of these detectors is resolution degradation due to Frisch grid microphonics. A coplanar-anode HPXe detector has been developed as an alternative to gridded chambers. An investigation of this detector’s energy resolution is reported in this submission. A simulation package is used to investigate the contributions of important physical processes to the measured photopeak broadening. Experimental data is presented for pure Xe and Xe+0.2%H2 mixtures, including an analysis of interaction location effects on the energy spectrum.

Kiff, Scott D.; He, Zhong; Tepper, Gary C.

2007-08-04

322

[Correction of the functional state of deck aviation pilots by the course of inhalation of therapeutic doses of xenon during long march].  

PubMed

The article deals with efficiency of the course of O2-Xe inhalation for correction of the functional state of deck aviation pilots in a long march. The course was shown to stabilize vagosympathetic balance in organism, to compensate functioning and to retain reserve of the cardiovascular system that resulted in significant psychoemotional animation attested by self-appreciation, amelioration and cheerfulness, and weakening of reactive anxiety. These observations point to applicability of xenon-based gas mixtures to correction of the pilot's functional state in the most intensive periods of service. Guidelines for broad adoption of the method by military medicine have been developed. PMID:21970037

Bubeev, Iu A; Kal'manov, A S; Kotrovskaia, T I

323

The fate of xenon-131 from iodine-131 absorbed on the silver zeolite samplers  

NASA Astrophysics Data System (ADS)

The purpose of this study was to investigate whether xenon-131, the decay daughter of I-131, was retained in or escaped from the silver zeolite cartridge after iodine-131 had been adsorbed in the cartridge. Currently, silver zeolite cartridges are used in the nuclear power industry to adsorb the radioactive iodine gas in sampling lines because of their high retention efficiency for gaseous iodine but not for noble gases. If xenon-131 is desorbed and escapes from the silver zeolite cartridge, the surfaces originally occupied by iodine-131 in the silver zeolite cartridge may be vacant and thus available to adsorb other iodine gas molecules. The reusability of silver zeolite cartridges may reduce the sampling cost and radioactive waste volume and also preserve the silver resource. A silver zeolite cartridge containing only iodine-131 of known activity in a cartridge holder was connected with a blank charcoal cartridge in another cartridge holder. The end of each cartridge holder was sealed so the diffusion of xenon was contained in a closed system. Radioactive xenon-131 m, the daughter of iodine-131, was used as an indicator for stable xenon-131. The absence or presence of xenon-131m on the charcoal cartridge was used to determine if xenon-131 was desorbed from the silver zeolite cartridge. A NaI scintillator was used to detect iodine-131 and a HPGe detector was used to detect xenon- 131 m. The desorption fraction of xenon-133 from the silver zeolite cartridge was found to be 0.66 +/- 4.3% and the retention fraction of xenon-133 in the charcoal cartridge was found to be 0.61 +/- 7.5%. Xenon-131m was frequently present in the charcoal cartridge. This showed that xenon131 was desorbed and escaped from the initial occupied sites in the silver zeolite cartridge after iodine-131 decayed. The amount of xenon-131m escaping from the silver zeolite cartridge fluctuated from day to day. This is thought to be due to what is known as the tunnel blocking effect. This effect has been described in the literature and involves the random location of xenon-131m atoms in the microscopic infrastructure of the silver zeolite.

Wang, Wei-Hsung

2000-09-01

324

[Effects of hyperoxic gas mixtures on the proliferative and migrative activities of cultivated endothelial cells of humans].  

PubMed

Proliferation and migration of endothelial cells of humans were studied in hyperoxic gas mixtures varying in percentage of oxygen and argon. Exposure to one or the other hyperoxic mixture was repeated, short (3 hrs) or long (18 hrs). The most significant inhibition of proliferation was observed after three long exposures in 100% O2 and the least signficant inhibition was caused by the gas mixture containing 89% of O2, 4.5% of Ar and 6.5% of N2 as an end-product of air separation with the short-cycle natural adsorption. Single 3-hr exposure to the hyperoxic mixture (5% Ar + 95% O2) activated EC migration, whereas repeated short exposure and single long exposure inhibited EC migration in vitro. PMID:17193968

Buravkova, L B; Grinakovskaia, O S; Merzlikina, N V

325

Calibration of gas pressure using the mercury melting curve in conjunction with eutectic ice-salt mixtures  

Microsoft Academic Search

Eutectic freezing mixtures of ice-KNO3, ice-KCl, ice-NH4Cl and ice-NaCl provide a convenient method of obtaining uniform temperatures close to -2.8, -10.6, -15.3 and -21.1 degrees C, respectively. Calibration to better than +or-0.1% is achievable for gas pressures between 344 and 701 MPa when these mixtures are used in conjunction with a mercury pressure cell and a resistance thermometer accurate to

J. Lusk

1990-01-01

326

Radioactive Plume from the Three Mile Island Accident: Xenon133 in Air at a Distance of 375 Kilometers  

Microsoft Academic Search

The transit of an air mass containing radioactive gas released from the Three Mile Island reactor was recorded in Albany, New York, by measuring xenon-133. These measurements provide an evaluation of Three Mile Island effluents to distances greater than 100 kilometers. Two independent techniques identified xenon-133 in ambient air at concentrations as high as 3900 picocuries per cubic meter. The

Martin Wahlen; Charles O. Kunz; John M. Matuszek; William E. Mahoney; Roger C. Thompson

1980-01-01

327

Production of H - ions with addition of cesium or xenon to a hydrogen discharge in a small multicusp ion source  

Microsoft Academic Search

The effect on H⁻ ion production by adding cesium or xenon to a hydrogen discharge, in a small magnetically filtered multicusp ion source, has been investigated. Addition of cesium vapor to the hydrogen discharge resulted in a factor of 16 increase in H⁻ output relative to the uncesiated discharge for the same operating parameters. Likewise, the addition of xenon gas

S. R. Walther; K. N. Leung; W. B. Kunkel

1988-01-01

328

Production of H? ions with addition of cesium or xenon to a hydrogen discharge in a small multicusp ion source  

Microsoft Academic Search

The effect on H? ion production by adding cesium or xenon to a hydrogen discharge, in a small magnetically filtered multicusp ion source, has been investigated. Addition of cesium vapor to the hydrogen discharge resulted in a factor of 16 increase in H? output relative to the uncesiated discharge for the same operating parameters. Likewise, the addition of xenon gas

S. R. Walther; K. N. Leung; W. B. Kunkel

1988-01-01

329

Effect Of Gas Mixture Composition On Tar Removal Process In A Pulsed Corona Discharge Reactor  

NASA Astrophysics Data System (ADS)

The simulation of naphthalene (C10H8) removal from several gas mixtures (pure nitrogen, mixtures containing N2 with CO2, CO, H2, H2O, and biogas - the product of biomass gasification), has been investigated. The modeling is based on the experimental data obtained in the reactor with a pulsed positive corona discharge. The problem of simulation of the cleaning process includes description of two stages. The first, fast stage is generation of primary active species during streamer propagation. The second, slow stage is the chain of chemical transformations triggered by these species. The input parameters for the modeling of the second stage are G-values for generation of primary active species, obtained under consideration of streamer dynamics. Simulation of the second stage of the removal process takes into account the processes of chemical kinetics and diffusion outside and inside of streamer traces during multi-pulsed treatment. Besides neutral active species, streamer discharges produce electrons and ions. Primary positive ions (N2+, CO+, CO2+, H2+, H2O+) in a chain of fast ion-molecule reactions transform into more stable positive ions. The ions recombine with electrons. Both ion-molecule reactions and electron-ion recombination process are additional (to dissociation of gas molecules by electron impact in the streamer head) sources of neutral active species. The relative contribution of these sources to the G-values for H, OH and O is rather large. In our modeling two approaches have been used. At the first approach the contribution of ion-molecule reactions is estimated approximately assuming that the dominating stable ion is N4+ (in pure N2 and its mixtures with H2) or CO2+ (in mixtures including CO2). Other way is the calculations with kinetic scheme including the molecular ions, aquated ions such as H3O(H2O)m+, NO2(H2O)-, NO2(H2O)+ and other. The comparison of results of two approaches is presented. Only full kinetic scheme allowed describing the experimental results for 82.5%N2+17.5%H2O mixture on C10H8 removal. Obtained dependencies of the remaining naphthalene fraction versus the specific energy input have been compared with the experimental data. The results agree rather well for considered mixtures. The best decomposition has been obtained in nitrogen with water vapor, a little better than that in pure nitrogen, both in experiments and in the simulation. It has been found that the reaction of naphthalene with excited nitrogen molecules N2(A3S) plays a key role in the removal process. Addition to N2 of such gases as CO, CO2 and H2 reduces the removal efficiency noticeably.

Filimonova E.; Naidis, G.

2010-07-01

330

Fluorine Compounds of Xenon and Radon  

Microsoft Academic Search

Xenon and fluorine combine readily. Xenon tetrafluoride is a colorless crystalline material, stable at room temperature. The existence of at least one other fluoride and two oxyfluorides has been demonstrated. The heaviest \\

C. L. Chernick; H. H. Claassen; P. R. Fields; H. H. Hyman; J. G. Malm; W. M. Manning; M. S. Matheson; L. A. Quarterman; F. Schreiner; H. H. Selig; I. Sheft; S. Siegel; E. N. Sloth; L. Stein; M. H. Studier; M. H. Zirin

1962-01-01

331

Adsorption of binary gas mixtures in heterogeneous carbon predicted by density functional theory: on the formation of adsorption azeotropes.  

PubMed

Classical density functional theory (DFT) was used to predict the adsorption of nine different binary gas mixtures in a heterogeneous BPL activated carbon with a known pore size distribution (PSD) and in single, homogeneous, slit-shaped carbon pores of different sizes. By comparing the heterogeneous results with those obtained from the ideal adsorbed solution theory and with those obtained in the homogeneous carbon, it was determined that adsorption nonideality and adsorption azeotropes are caused by the coupled effects of differences in the molecular size of the components in a gas mixture and only slight differences in the pore sizes of a heterogeneous adsorbent. For many binary gas mixtures, selectivity was found to be a strong function of pore size. As the width of a homogeneous pore increases slightly, the selectivity for two different sized adsorbates may change from being greater than unity to less than unity. This change in selectivity can be accompanied by the formation of an adsorption azeotrope when this same binary mixture is adsorbed in a heterogeneous adsorbent with a PSD, like in BPL activated carbon. These results also showed that the selectivity exhibited by a heterogeneous adsorbent can be dominated by a small number of pores that are very selective toward one of the components in the gas mixture, leading to adsorption azeotrope formation in extreme cases. PMID:20712330

Ritter, James A; Pan, Huanhua; Balbuena, Perla B

2010-09-01

332

Process for the separation of air components, such as difficultly absorbable air impurities, out of air-gas mixtures  

SciTech Connect

The present invention provides an apparatus and process for separating and removing chemical impurities from air which impurities are difficult to absorb. The apparatus for carrying out the process of the present invention comprises a reaction tower (11, 15, 91) into which the air-gas mixture is fed, aperture means (35, 74, 96) in a wall (16, 60, 98) of the tower, at least one filter means (12, 52, 92) carried in the reaction tower, means for distributing (13, 58, 93) an absorbent medium onto the filter, collecting means (14, 54, 94) beneath the filter for collection of the absorbent medium passing through the filter, and fan means (15, 55, 95) provided in the aperture for creating a flow of air through the reaction tower for the separation of substantially all of the impurities therefrom. The process of the present invention for the separation of chemical air impurities from air-gas mixtures comprises the steps of distributing an absorbent medium over at least one pack of stratified filter mats carried in a reaction tower, introducing the air-gas mixture to the filter mats and, creating a flow of air through the tower whereby the air-gas mixture is drawn through the filter mats and exits from the tower substantially free of chemical impurities. Absorbent medium such as caustic soda, sodium hypochlorite, water, hydrogen peroxide and mixtures thereof is particularly useful.

Zakrzewski, E.

1984-07-17

333

The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.  

SciTech Connect

Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).

Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard

2005-07-01

334

Enhancing the observability of the Efimov effect in ultracold atomic gas mixtures  

SciTech Connect

We discuss the prospects for observing the characteristic features of the Efimov effect in a two-component ultracold atomic gas near an interspecies Feshbach resonance. In the ultracold regime, the Efimov effect is expected to be manifested in the three-body collision rates through the appearance of series of minima or maxima as a function of the two-body s-wave scattering length a. Here, we propose the observation of this Efimov physics through measurements of the inelastic three-body rate constants near a Feshbach resonance. Our analysis suggests that boson-fermion mixtures, where the bosons are much heavier than the fermions, are the most favorable system to observe such features.

D'Incao, J. P.; Esry, B. D. [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

2006-03-15

335

Unstructured Adaptive Grid Flow Simulations of Inert and Reactive Gas Mixtures  

NASA Astrophysics Data System (ADS)

Unstructured adaptive grid flow simulation is applied to the calculation of high-speed compressible flows of inert and reactive gas mixtures. In the present case, the flowfield is simulated using the 2-D Euler equations, which are discretized in a cell-centered finite volume procedure on unstructured triangular meshes. Interface fluxes are calculated by a Liou flux vector splitting scheme which has been adapted to an unstructured grid context by the authors. Physicochemical properties are functions of the local mixture composition, temperature, and pressure, which are computed using the CHEMKIN-II subroutines. Computational results are presented for the case of premixed hydrogen-air supersonic flow over a 2-D wedge. In such a configuration, combustion may be triggered behind the oblique shock wave and transition to an oblique detonation wave is eventually obtained. It is shown that the solution adaptive procedure implemented is able to correctly define the important wave fronts. A parametric analysis of the influence of the adaptation parameters on the computed solution is performed.

Figueira da Silva, L. F.; Azevedo, João L. F.; Korzenowski, Heidi

2000-05-01

336

Unstructured adaptive grid flow simulations of inert and reactive gas mixtures  

SciTech Connect

Unstructured adaptive grid flow simulation is applied to the calculation of high-speed compressible flows of inert and reactive gas mixtures. In the present case, the flowfield is simulated using the 2-D Euler equations, which are discretized in a cell-centered finite volume procedure on unstructured triangular meshes. Interface fluxes are calculated by a Liou flux vector splitting scheme which has been adapted to an unstructured grid context by the authors. Physicochemical properties are functions of the local mixture composition, temperature, and pressure, which are computed using the CHEMKIN-II subroutines. Computational results are presented for the case of premixed hydrogen-air supersonic flow over a 2-D wedge. In such a configuration, combustion may be triggered behind the oblique shock wave and transition to an oblique detonation wave is eventually obtained. It is shown that the solution adaptive procedure implemented is able to correctly define the important wave fronts. A parametric analysis of the influence of the adaptation parameters on the computed solution is performed.

Figueira da Silva, L.F.; Azevedo, J.L.F.; Korzenowski, H.

2000-05-20

337

Measurement of activity coefficients of mixtures by head-space gas chromatography: general procedure.  

PubMed

Head-space gas chromatography (HS-GC) is an applicable method to perform vapor-liquid equilibrium measurements and determine activity coefficients. However, the reproducibility of the data may be conditioned by the experimental procedure concerning to the automated pressure-balanced system. The study developed in this work shows that a minimum volume of liquid in the vial is necessary to ensure the reliability of the activity coefficients since it may become a parameter that influences the magnitude of the peak areas: the helium introduced during the pressurization step may produce significant variations of the results when too small volume of liquid is selected. The minimum volume required should thus be evaluated prior to obtain experimentally the concentration in the vapor phase and the activity coefficients. In this work, the mixture acetonitrile-toluene is taken as example, requiring a sample volume of more than 5mL (about more than 25% of the vial volume). The vapor-liquid equilibrium and activity coefficients of mixtures at different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 molar fraction) and four temperatures (35, 45, 55 and 70°C) have been determined. Relative standard deviations (RSD) lower than 5% have been obtained, indicating the good reproducibility of the method when a sample volume larger than 5mL is used. Finally, a general procedure to measure activity coefficients by means of pressure-balanced head-space gas chromatography is proposed. PMID:23809803

Luis, Patricia; Wouters, Christine; Van der Bruggen, Bart; Sandler, Stanley I

2013-06-14

338

Introducing Hyperpolarized Xenon-131 Directly Detected by NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

Previously, high-field NMR and MRI applications of hyperpolarized (hp) noble gasses focused on the isotopes helium-3 (spin I = 1/2), xenon-129 (spin I = 1/2) [1], and more recently krypton-83 (spin I = 9/2) [2]. In this contribution, hp xenon-131 (spin I = 3/2) was generated by spin-exchange optical pumping and separated from the rubidium vapor for high field NMR detection at 14.1 T field strength. Xenon-131 is of particular interest because of its quadrupolar nature that can be utilized for the study of surfaces [3] and for the investigation of high magnetic field effects on the electronic structure of the noble gas atom [4]. In addition, this isotope is a useful probe for quadrupolar processes during gas transfer and during NMR/MRI detection. Experiments with xenon-131, including multiple quantum filtered NMR spectroscopy [3], provides insights into similar processes present in krypton-83 and its more complicated spin system [5]. [1] D. Raftery Ann. Rep. NMR Spec., 57, 208 (2006). [2] G. Pavlovskaya, et al., Pro. Natl. Acad. Sci. U.S.A. 102, 18275 (2005). [3] T. Meersmann et al., Phys. Rev. Lett. 80, 1398 (1998). [4] T. Meersmann and M. Haake, Phys. Rev. Lett. 81, 1211 (1998). [5] Z. Cleveland, et al., J. Chem. Phys.124, 044312 (2006).

Stupic, Karl; Cleveland, Zackary; Pavlovskaya, Galina; Meersmann, Thomas

2007-03-01

339

Vapor–liquid equilibria of LNG and gas condensate mixtures by the Nasrifar–Moshfeghian equation of state  

Microsoft Academic Search

The Nasrifar–Moshfeghian (NM) equation of state (EOS) is used to predict vapor–liquid equilibria (VLE) of multi-component mixtures. The systems under study consist of liquefied natural gases (LNG), gas condensates, an asymmetric system, slightly polar systems and gas\\/water systems. van der Waals mixing rules are used and no pure component parameter is adjusted; however, the predictions compare well with experimental data,

Kh Nasrifar; M Moshfeghian

2002-01-01

340

Separation of gas mixtures by supported complexes. Final report, 1 October 1982-30 September 1984  

SciTech Connect

This final report covers research performed to identify and demonstrate advantageous procedures for the chemical separation of gases, such as CO, CO/sub 2/, and H/sub 2/, from medium-Btu gas mixtures by use of supported complexes. Three complexes were chosen for rapid gas uptake and selectivity at 25/sup 0/C from among a group of 22 coordination complexes synthesized during this program. The three complexes showed considerable selectivity toward individual gases. For instance, Pd/sub 2/(dpm)/sub 2/Cl/sub 2/ or bis-..mu..-(bisdiphenylphosphinomethane)-dichlorodipalladium (Pd-Pd), rapidly bound carbon monoxide from solution. This complex could be regenerated, with the carbon monoxide reversibly removed, by warming to 40/sup 0/C. The presence of other gases, such as carbon dioxide, oxygen, nitrogen, hydrogen, ethylene, or acetylene, had no effect upon the rapid uptake of carbon monoxide or its removal. Such selectivity was also noted with Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, biscarbonyltris(triphenylphosphine)ruthenium. Although this complex bound hydrogen, carbon monoxide, and oxygen in solution, the hydrogen was taken up twice as fast as carbon monoxide and seven times faster than oxygen. These gases could be removed from the complex with mild heat or decreased pressure. Crystalline Rh(OH)(CO)(PPh/sub 3/)/sub 2/, hydroxocarbonylbis(triphenylphosphine)rhodium, rapidly bound carbon dioxide; the complex was regenerated at 50/sup 0/C under reduced pressure. The rapid uptake of carbon dioxide by this complex was not changed in the presence of oxygen. In general the three selected crystalline or solvent dissolved complexes performed well in the absence of polymeric support. The stability and favorable kinetics of the three complexes suggest that they could be utilized in a solution system for gas separation (Conceptual Analyses and Preliminary Economics). Further, these complexes appear to be superb candidates as transport agents for facilitated-transport, membrane systems. 69 references, 21 figures.

Nelson, D.A.; Hallen, R.T.; Lilga, M.A.

1985-01-01

341

Revised and Extended Analysis of Six Times Ionized Xenon: Xe VII  

Microsoft Academic Search

The spectra of xenon were recorded in the 100-1250 Å region on a variety of vacuum spectrographs at the Antigonish, NIST and Troitsk laboratories. The source used at the Antigonish and the NIST laboratories was a xenon-gas-puff low inductance vacuum spark while at the Troitsk laboratory it was a 40 kV fast capillary discharge. On the basis of our new

S. S. Churilov; Y. N. Joshi

2002-01-01

342

Global characteristics of an ATON stationary plasma thruster operating with krypton and xenon  

Microsoft Academic Search

The global characteristics of an ATON stationary plasma thruster operating on xenon and krypton are investigated. It is shown\\u000a that, with krypton, the thrust at the same mass flow rate of the working gas is greater and the efficiency is somewhat lower\\u000a than those with xenon. An efficiency of ?60% was achieved with krypton for the specific impulse attaining 3000

A. I. Bugrova; A. S. Lipatov; A. I. Morozov; L. V. Solomatina

2002-01-01

343

Prevention of fog in the condensation of vapour from mixtures with inert gas, by a regenerative thermal process  

Microsoft Academic Search

In processing, vapours often have to be separated from mixtures mainly containing inert gas, as for example in the cleaning of exhaust air and the recovery of pollutant solvent vapours (volatile organic compounds, VOC). Whenever possible, condensation is applied for this task, since it is thermodynamically the most energy-efficient process. It can be carried out successfully, provided that the vapour

Stephan Kaufmann; Karl Hilfiker

1999-01-01

344

The effect of porous barriers on the molecular composition and total flux of a reactive gas mixture  

Microsoft Academic Search

When a gas mixture that is governed by a pressure dependent equilibrium is passed through a porous barrier, the exit molecular fluxes are functions of the equilibrium constant and the atomic concentrations at the exit face of the barrier rather than of the molecular weights and impingement pressures as has been tacitly assumed for Knudsen flow conditions. It is shown

Pirooz Mohazzabi; Alan W. Searcy

1976-01-01

345

Measurements of viscosity, velocity slip coefficients and tangential momentum accommodation coefficients for gas mixtures using a spinning rotor gauge  

NASA Astrophysics Data System (ADS)

A selection of experimental measurements for He-Ar, He-N2, and He-Ne binary gas mixtures which have been made with a spinning rotor gauge (SRG; MKS Instruments, Inc.) are reported. All of the experiments were conducted in the slip regime. Theoretical results are used to extract values of the viscosity and the velocity slip coefficient from the experimentally obtained data for each of the gas mixtures. Slip coefficients for binary gas mixtures have not previously been reported. An important issue here is whether or not the velocity slip coefficients for binary gas mixtures can be predicted accurately using separately measured tangential momentum accommodation coefficients. Calculation of slip coefficients from theory requires a knowledge of the accommodation coefficients of each constituent of the mixture. The dependence of these coefficients on the gas composition is not known and the simplest assumption is to regard them as being independent of the composition. The slip coefficients computed in conjunction with this work use this simple assumption in a theoretical expression for the slips. These computations led to reasonable agreement of the theoretical results with our data for the He-Ne mixture. Agreement in the cases of the He-Ar and He-N2 mixtures, however, was less than satisfactory. Also reported are a selection of experimental viscosity and slip measurements for He and Ar made with a modified spinning rotor gauge. Currently available SRGs operate in a horizontal mode where the axis of the tube containing the spherical rotor is orthogonal to the angular momentum vector of the rotor. The theory, however, specifies that the angular momentum vector of the rotor should lie along the cylinder axis. This alignment difference doesn't prohibit the desired measurements from being made but does require that existing SRGs be calibrated against a known standard gas to account for the geometric differences. The geometry factor in the theory is known explicitly, however, when the rotor angular momentum vector is aligned with the cylinder axis. The implication of this is that a properly designed and aligned system can be used to measure viscosities and slips directly without reference to a known standard gas. Measurements made with this modified version of the SRG are compared with previous experimental results from the standard SRG.

Bentz, Julie A.

346

Biotreatment of a gas-phase volatile mixture from fibreglass and composite manufacturing industries.  

PubMed

Acetone, toluene and styrene (ATS) are representative air pollutants emanating during the production process in fibreglass and composite manufacturing industries. In this study, the performance of a steady-state biofilter inoculated with the fungus Sporothrix variecibatus was tested at different empty bed residence times (EBRTs), and at different inlet concentrations of ATS, corresponding to total pollutant loading rates ranging from 30 to 490 gm(-3)hour(-1). Styrene was somewhat better removed (47-100%) in the biofilter than acetone (34-100%) and toluene (42-100%), with maximum elimination capacities (EC(max)) of 108, 72 and 144 gm(-3)hour(-1), for ATS, respectively. Besides, it was observed that, although increasing the concentration of ATS decreased their removal, the presence of toluene also decreased the EC(max) of both acetone and toluene in the ternary mixture. During transient operations, the biofilter was subjected to intermittent shutdown and re-start operations where the gas-phase pollutant flow was stopped for either 5 or 16d. It was observed that, for longer shutdown periods (16d), the biofilter required nearly 8-10d to reach similar removal patterns to those observed before the shutdown phase. Batch biodegradation tests were conducted, using Sporothrix-like microorganisms present in the leachate of the biofilter, with a mixture of ATS as the sole carbon source. Complete removal of ATS was observed within the test period of 168 hours. Styrene was degraded faster, with a specific substrate utilization rate of 0.9 mg styrenemg biomass(-1)hour(-1), followed by toluene (0.6) and acetone (0.44). The effectiveness of the biofilter to reach high total EC (321.3 gm(-3)hour(-1)), and withstand transient operations shows the robustness of this fungal-bioreactor and its suitability to handle emissions from a fibreglass and composite manufacturing industry. PMID:21911090

Rene, Eldon R; Montes, María; Veiga, María C; Kennes, Christian

2011-09-03

347

Numerical study on xenon positive column discharges of mercury-free lamp  

SciTech Connect

In this paper, the numerical study has been performed on the xenon positive column discharges of mercury-free fluorescent lamp. The plasma discharge characteristics are analyzed by numerical simulation based on two-dimensional fluid model. The effects of cell geometry, such as the dielectric layer, the electrode width, the electrode gap, and the cell height, and the filling gas including the pressure and the xenon percentage are investigated in terms of discharge current and discharge efficiency. The results show that a long transient positive column will form in the xenon lamp when applying ac sinusoidal power and the lamp can operate in a large range of voltage and frequency. The front dielectric layer of the cell plays an important role in the xenon lamp while the back layer has little effect. The ratio of electrode gap to cell height should be large to achieve a long positive column xenon lamp and higher efficiency. Increase of pressure or xenon concentration results in an increase of discharge efficiency and voltage. The discussions will be helpful for the design of commercial xenon lamp cells.

Ouyang, Jiting; He, Feng; Miao, Jinsong; Wang, Jianqi; Hu, Wenbo [School of Science, Beijing Institute of Technology, P.O. Box 327, Beijing 100081 (China); Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China)

2007-02-15

348

10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.  

Code of Federal Regulations, 2010 CFR

...fuel as a primary energy source; ...input of the primary energy sources needed...used; and (4) Environmental impact analysis as required...regulations. (c) Solar mixtures. OFE...mixture of solar energy (including...

2009-01-01

349

10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.  

Code of Federal Regulations, 2010 CFR

...fuel as a primary energy source; ...input of the primary energy sources needed...used; and (4) Environmental impact analysis as required...regulations. (c) Solar mixtures. OFE...mixture of solar energy (including...

2010-01-01

350

Combustion of lean prevaporized fuel–air mixtures mixed with hot burned gas for low-NO x emissions over an extended range of fuel–air ratios  

Microsoft Academic Search

Reaction of lean to ultra-lean mixtures supported by high-temperature burned gas can resolve the dilemma between complete combustion versus ultra-low NOx emissions in lean premixed gas turbine combustors. The combustion characteristics and NOx emissions in “lean–lean” two-stage combustion were investigated for premixed–prevaporized kerosene–air mixtures using a co-axial flow configuration. Secondary prevaporized kerosene–air mixtures of lean to ultra-lean compositions were injected

Naoki Aida; Tomoki Nishijima; Shigeru Hayashi; Hideshi Yamada; Tadashige Kawakami

2005-01-01

351

Spectroscopic investigations of high-power laser-induced dielectric breakdown in gas mixtures containing carbon monoxide.  

PubMed

Large-scale plasma was created in gas mixtures containing carbon monoxide by high-power laser-induced dielectric breakdown (LIDB). The composition of the mixtures used corresponded to a cometary and/or meteoritic impact into the Earth's early atmosphere. A multiple-centimeter-sized fireball was created by focusing a single 85 J, 450 ps near-infrared laser pulse into the center of a 15 L gas cell. The excited reaction intermediates that formed in various stages of the LIDB plasma chemical evolution were investigated by optical emission spectroscopy (OES) with temporal resolution. Special attention was paid to any OES signs of molecular ions. However, carbon monoxide cations were registered only if their production was enhanced by Penning ionization, i.e., excess He was added to the CO. The chemical consequences of laser-produced plasma generation in a CO-N 2-H 2O mixture were investigated using high resolution Fourier-transform infrared absorption spectroscopy (FTIR) and gas chromatography (GC). Several simple inorganic and organic compounds were identified in the reaction mixture exposed to ten laser sparks. H 2 (18)O was used to avoid possible contamination. The large laser spark triggered more complex reactivity originating in carbon monoxide than expected, when taking into account the strong triple bond of carbon monoxide causing typically inefficient dissociation of this molecule in electrical discharges. PMID:18636696

Civis, Svatopluk; Babánková, Dagmar; Cihelka, Jaroslav; Sazama, Petr; Juha, Libor

2008-07-17

352

Deactivation of xenon atoms in the 6s resonant state in collisions with xenon and helium atoms  

SciTech Connect

The absorption probing method was used to investigate collisional deactivation of the 6s[3/2]{sub 1}{sup 0}({sup 3}P{sub 1}) state of the xenon atom in high-pressure He - Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the following plasma-chemical reactions: Xe* + Xe + He {yields} Xe{sub 2}* + He [(2.1 {+-} 0.2) x 10{sup -32} cm{sup 6}s{sup -1}], Xe* + 2He {yields} HeXe* + He (less than 10{sup -35} cm{sup 6}s{sup -1}), and Xe* + He {yields} products + He (less than 3 x 10{sup -15} cm{sup 3}s{sup -1}). (active media)

Zayarnyi, D A; Semenova, Ludmila V; Ustinovskii, N N; Kholin, I V; Chugunov, A Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1999-02-28

353

Deactivation of the xenon atom in the 6s metastable state in collisions with xenon and helium atoms  

SciTech Connect

The absorption probing method was used to investigate collisional deactivation of the metastable 6s[3/2]{sub 2}{sup 0}({sup 3}P{sub 2}) state of the xenon atom in high-pressure He - Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the plasma-chemical reactions Xe*+Xe+He {yields} Xe{sub 2}*+He [(1.7 {+-}0.2) x10{sup -32} cm{sup 6} s{sup -1}], Xe*+2He{yields} HeXe*+He (less than 3 x 10{sup -35} cm{sup 6} s{sup -1}), and Xe*+He{yields} products+He (less than 10{sup -15} cm{sup 3} s{sup -1}). (active media)

Zayarnyi, D A; Semenova, Ludmila V; Ustinovskii, N N; Kholin, I V; Chugunov, A Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1998-03-31

354

Spectral Characteristics of Deuterium-, Helium- and Gas-Mixture-Discharges within PF-1000 Facility  

SciTech Connect

The paper reports on spectroscopic studies of high-current plasma discharges performed at different gas fillings within the large PF-1000 facility. To study visible radiation (VR) the use was made of a MECHELLE registered 900-spectrometer equipped with the CCD readout. The observations of a PF pinch column were performed at an angle of about 65 deg. to the z-axis, and the viewing field was at a distance of 40-50 mm from the electrode ends. Optical measurements were carried out at 0.5-{mu}s exposition synchronized with a chosen period of the investigated discharge. Differences in the optical spectra, recorded at various deuterium-helium mixtures, were analyzed. Intensities of HeI lines were computed for an assumed electron temperature and compared with the experiment. Estimated plasma concentration in pure-deuterium discharges amounted to 8x1018 cm-3, while that in pure helium shots was (4-7)x1017 cm-3 only. Estimates of the electron temperature, from the ratio of intensities of the chosen spectral lines and the continuum, gave values ranging from 5 eV to 50 eV. The paper presents also some spectra from 'weak shots', which show distinct impurity lines caused by different reasons.

Tsarenko, A. [Institute of Plasma Physics, NSC KIPT, 61-108 Kharkov (Ukraine); Malinowski, K.; Skladnik-Sadowska, E. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Sadowski, M. J. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Institute of Plasma Physics and Laser Microfusion, 00-908 Warsaw (Poland); Scholz, M.; Paduch, M.; Tomaszewski, K. [Institute of Plasma Physics and Laser Microfusion, 00-908 Warsaw (Poland)

2006-01-15

355

Enhanced technique for measuring collisional quenching rate coefficients in rare-gas mixtures  

SciTech Connect

We set forth an improved technique for the investigation of collisional quenching in high-pressure rare-gas mixtures, which relies on the absorption probing measurements of the decay rates of the excited states of these gases in the afterglow of a fast electron beam discharge. We determined more precisely the rate coefficients of the plasmochemical reactions Xe* + Xe + Ar {yields} Xe{sub 2}* and Xe*+Ar {yields} products + Ar for the metastable (6s[3/2]{sub 2}{sup 0}) and resonance (6s[3/2]{sub 1}{sup 0}) levels of atomic Xe investigated in our earlier work. The rate coefficients for the reactions Xe(6s[3/2]{sub 2}{sup 0}) + 2Ar {yields} ArXe* + Ar((7.2{+-}1.4)x10{sup -36} cm{sup 6} s{sup -1}) and Xe(6s[3/2]{sub 1}{sup 0}) + 2Ar {yields} ArXe*((5.3{+-}2.4)x10{sup -36} cm{sup 6} s{sup -1}) were measured for the first time. (active media)

Zayarnyi, D A; L'dov, A Yu; Kholin, I V [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2011-02-28

356

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1995  

SciTech Connect

The contract objectives are: to design a catalytic material for the synthesis of isobutanol with a productivity of 200 g isoalcohols/g-cat-h and a molar isobutanol/methanol ratio near unity; and to develop structure-function rules for the design of catalysts for the selective conversion of synthesis gas to isoalcohols. Several catalyst samples have been prepared by controlled co-precipitation from aqueous mixtures of metal nitrates. The composition of these materials is based on reports of best available catalysts for methanol synthesis, for isobutanol synthesis, and for methanol coupling reactions. The mechanical construction and pressure testing of the microreactor system has been completed. The in-situ infrared spectrophotometer equipped with a nitrogen purge is fully operational. The temperature-programmed surface reaction (TPSR) unit has been designed; construction will begin during the third quarter FY`95. Air Products and Chemicals has provided us with a sample of a BASF isobutanol synthesis catalyst and with catalytic data obtained on this catalyst in a LaPorte test run. This catalyst will serve as a benchmark for the certification of our new microreactor system.

Iglesia, E.

1995-04-24

357

Studies of Helium Based Gas Mixtures Using a Small Cell Drift Chamber  

SciTech Connect

An international collaboration is currently working on the construction and design of an asymmetric B Factory at the Stanford Linear Accelerator Center that will be ready to collect data in 1999. The main physics motivation for such a facility is to test the description and mechanism of CP violation in the Standard Model of particle physics and provide insight into the question of why more matter than antimatter is observed in the universe today. In particular, this experiment will measure CP violation in the decay of B mesons. In the early stages of this effort, the Canadian contingent proposed to build the central tracking chamber for the BaBar detector. Presently, a prototype drift chamber is in operation and studies are being performed to test some of the unique features of drift chamber design dictated by the conditions of the experiment. Using cosmic muons, it is possible to study tracking and pattern recognition in the prototype chamber, and therefore calculate the efficiency and spatial resolution of the prototype chamber cells. These performance features will be used to test whether or not the helium-based gas mixtures proposed for the BaBar drift chamber are a viable alternative to the more traditional argon-based gases.

Heise, Jaret; /British Columbia U.

2006-07-07

358

Direct Prediction of Cricondentherm and Cricondenbar Coordinates of Natural Gas Mixtures using Cubic Equation of State  

NASA Astrophysics Data System (ADS)

A numerical algorithm is presented for direct calculation of the cricondenbar and cricondentherm coordinates of natural gas mixtures of known composition based on the Michelsen method. In the course of determination of these coordinates, the equilibrium mole fractions at these points are also calculated. In this algorithm, the property of the distance from the free energy surfaces to a tangent plane in equilibrium condition is added to saturation calculation as an additional criterion. An equation of state (EoS) was needed to calculate all required properties. Therefore, the algorithm was tested with Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), and modified Nasrifar-Moshfeghian (MNM) equations of state. For different EoSs, the impact of the binary interaction coefficient ( k ij) was studied. The impact of initial guesses for temperature and pressure was also studied. The convergence speed and the accuracy of the results of this new algorithm were compared with experimental data and the results obtained from other methods and simulation softwares such as Hysys, Aspen Plus, and EzThermo.

Taraf, R.; Behbahani, R.; Moshfeghian, Mahmood

2008-12-01

359

Pulse Shape in 2-Phase Xenon Detectors  

NASA Astrophysics Data System (ADS)

Understanding the shape and size of the primary (S1) and secondary (S2) scintillation pulses in noble elements is crucial for discriminating between different particle interactions. Monte Carlo results from NEST (the Noble Element Simulation Technique) will be presented which match the available data from liquid xenon on the dependence of the recombination time, which is a critical piece of the S1 pulse timing structure, on dE/dx, interaction type, and electric field magnitude. In addition, a model for the S2 pulse shape and the dependence of its width on the depth of an interaction in a detector will be presented which takes into account drift speed, the single/triplet time constants, diffusion, thermal electron trapping at a liquid-gas interface, and other effects.

Mock, Jeremy

2013-04-01

360

Recovery of methane from gas hydrates intercalated within natural sediments using CO(2) and a CO(2)/N(2) gas mixture.  

PubMed

The direct recovery of methane from massive methane hydrates (MHs), artificial MH-bearing clays, and natural MH-bearing sediments is demonstrated, using either CO(2) or a CO(2)/N(2) gas mixture (20 mol % of CO(2) and 80 mol % of N(2), reproducing flue gas from a power plant) for methane replacement in complex marine systems. Natural gas hydrates (NGHs) can be converted into CO(2) hydrate by a swapping mechanism. The overall process serves a dual purpose: it is a means of sustainable energy-source exploitation and greenhouse-gas sequestration. In particular, scant attention has been paid to the natural sediment clay portion in deep-sea gas hydrates, which is capable of storing a tremendous amount of NGH. The clay interlayer provides a unique chemical-physical environment for gas hydrates. Herein, for the first time, we pull out methane from intercalated methane hydrates in a clay interlayer using CO(2) and a CO(2)/N(2) gas mixture. The results of this study are expected to provide an essential physicochemical background required for large-scale NGH production under the seabed. PMID:22730158

Koh, Dong-Yeun; Kang, Hyery; Kim, Dae-Ok; Park, Juwoon; Cha, Minjun; Lee, Huen

2012-06-22

361

Working process study of a novel scroll type multiphase pump for the transportation of gas-liquid mixtures  

NASA Astrophysics Data System (ADS)

A novel scroll type multiphase pump was proposed to transport gas-liquid two-phase mixture. There is a pressure unloading gap from compression chambers to the discharge port by constructing scroll wrap profile with variational meshing clearance in this scroll multiphase pump. In the working process when the volume of working chamber decreases, the pressure of gas-liquid mixtures increases gradually, at the same time small amounts of gas-liquid mixture are pushed to the discharge port from compression chambers through the pressure unloading gap. Therefore, this multiphase pump has an advantage of unloading pressure method automatically, and the frequently problem of liquid impacting in volume multiphase pump is solved. The safety and reliability of volumetric multiphase pump are improved, and the scope of multiphase pump of the gas-liquid ratio is expanded. The working process and the performance characteristics of scroll multiphase pump were analyzed too, and the generation method of scroll wrap profile with variational meshing clearance was investigated. The equations of the profile were obtained, and the changing principle of the working volume and the meshing clearance were analyzed. The geometric theory of scroll multiphase pump was formed. All of that lay the theoretical foundation for engineering design of this novel scroll.

Wang, J.; Zha, H. B.; Zhang, X. H.; Zhang, D. H.

2012-11-01

362

Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model  

SciTech Connect

The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO{sub 2} sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO{sub 2} on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO{sub 2} on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties.

Fitzgerald, J.E.; Robinson, R.L.; Gasem, K.A.M. [Oklahoma State University, Stillwater, OK (United States). School of Chemical Engineering

2006-11-07

363

Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model.  

PubMed

The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO2 sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO2 on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO2 on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties. PMID:17073487

Fitzgerald, James E; Robinson, Robert L; Gasem, Khaled A M

2006-11-01

364

Study of pulsed neon-xenon VUV radiating low pressure plasmas for mercury free fluorescent sign optimization  

NASA Astrophysics Data System (ADS)

This work deals with the study and optimization of mercury free fluorescent discharge tubes for publicity lighting applications. The experimental set-up allows for time resolved spectroscopy from 110 up to 900 nm, photometric characterization in a large volume integrating sphere and the current and voltage measurement of microsecond duration signals delivered by lab-developed pulsed drivers. The glow and afterglow radiative process analysis indicates that the best performance measured with the pulsed excitation of rare gas plasma, in comparison with the conventional ac excitation, essentially originates from the efficient plasma relaxation during the afterglow at the benefit of the vacuum ultraviolet (VUV) resonance line radiated at 146.9 nm for xenon. The fit of the VUV time resolved experimental measurements, with the results issued from a simplified kinetic model of neon-xenon plasmas, evidences the crucial role of production of molecular ions during the glow phase and of their radiative recombination during the afterglow. The pulse duration and the gas mixture pressure appear as two experimental parameters whose influence, studied over an extended range, has been demonstrated to bring about a significant sign performance enhancement. There exists an optimum pulse duration range, which results in the appearance of limited stepwise excitation and ionization processes, favourable for an intense afterglow VUV production. The pressure dependence study shows that the best performance for pulsed excitation is obtained in Ne/Xe (100/1) mixtures around 50 mbar, at the difference of an ac driven Ne/Xe plasma for which the best conditions were reported to be of a few millibars. This pressure increase results both in the VUV and sign light output enhancement and the successful continuous operation of pulsed mercury free signs for time as long as 4000 h with neither electrode erosion, nor glass or phosphor degradation nor chromatic coordinate variation. For the green phosphor covered, 65 cm long and 13 mm inner diameter signs, the efficiency of a pulsed neon-xenon discharge likely to be operated for a few thousand hours reaches 50% of that of the same tube filled with mercury based mixtures.

Robert, E.; Point, S.; Dozias, S.; Viladrosa, R.; Pouvesle, J. M.

2010-04-01

365

Oxide and oxide fluorides of xenon(IV) and new developments in xenon(II), and krypton(II) chemistry  

Microsoft Academic Search

This Thesis extends the fundamental chemistry of the noble-gas elements, namely, xenon and krypton. More specifically, the chemistry of Xe(IV) has been extended by the synthesis and characterization of Xe(IV) oxide and oxide fluoride derivatives. The syntheses of XeOF2, F2OXeN?CCH 3, and XeOF2 ˙nHF and their structural characterizations are described. All three compounds are endothermic and explosive at temperatures approaching

David S Brock

2011-01-01

366

The importance of thermal mass diffusion effects in solution of Navier-Stokes equations for some gas mixture problems  

NASA Astrophysics Data System (ADS)

A computer code has been developed for numerical computation of compressible turbulent Navier-Stokes equations in general curvilinear coordinates, to solve binary perfect gas mixture flows. The prepared algorithm and the computer code are capable of modeling mixture effects in different fluid flows including viscous and mass diffusion effects. The Roe's numerical scheme is used to discretize the convective terms of governing fluid flow equations and simple upwinding method is used to discretize the equation of continuity of species. A complete model for mass diffusion which consists of ordinary, thermal and pressure terms is employed. The goal of this study is to investigate effects of viscosity, mass diffusion and especially thermal diffusion, on flow fields consisting of different mixtures. It is shown that the thermal mass diffusion can have profound effect on some flow fields, especially when the temperature gradient is not small. However, pressure mass diffusion can be negligible in the most of conventional problems.

Kamali, Reza; Emdad, Homayoon; Alishahi, Mohammad M.

2005-09-01

367

The XENON dark matter experiment: status of the XENON10 phase  

NASA Astrophysics Data System (ADS)

The XENON experiment searches for Weakly Interacting Massive Particles (WIMPs) with liquid Xenon as the active target. The proposed XENON1T detector is designed to achieve a sensitivity more than a factor of thousand beyond current limits. The collaboration is now testing the 10 kg target: the XENON10 detector was recently installed at the Gran Sasso Underground Laboratory and the first phase of data taking is underway.

the XENON Collaboration; Monzani, Maria Elena

2011-12-01

368

Isotopes of tellurium, xenon and krypton in Allende meteorite retain record of nucleosynthesis  

Microsoft Academic Search

Various mixtures of r-, p- and s-nucleosynthesis products have been observed in the isotopes of tellurium, xenon and krypton extracted from mineral separates of the Allende meteorite. The presence of several isotopically distinct components in these high Z elements and the close association of isotopically normal low Z elements with particular isotopes of the high Z elements suggest that our

R. V. Ballad; L. L. Oliver; R. G. Downing; O. K. Manuel

1979-01-01

369

Mass spectrometric measurement of end-tidal xenon concentration for clinical stable xenon/computerized tomography cerebral blood flow studies.  

PubMed

We have demonstrated the feasibility of using a compact dedicated mass spectrometer to monitor end-tidal xenon concentration in human subjects during stable xenon computerized tomography measurements of regional cerebral blood flow. End-tidal carbon dioxide concentration is monitored simultaneously and noninvasively without degrading the dynamic response to xenon. For clinical regional cerebral blood flow studies we employed a Nuclide 3-60-G Sectorr mass spectrometer with a 3 in radius, 60 degrees magnetic sector and a variable (0-5000 V) ion accelerating potential. The required high vacuum (10(-7) Torr) was achieved and maintained by means of a turbomolecular pump. A needlemetering valve was incorporated into an anesthesia mask connector, and exhaled gases were transported to the mass spectrometer via a 6 ft length of Teflon tubing (1/16 in i.d.). Molecular flow conditions between the sample and analysis chambers were provided by use of a gold foil leak (0.0005 in. hole). At an inlet pressure of 400 m Torr (achieved by means of the needle valve), the inlet system was characterized by a gas transport lag-time of 1.3 s and a rise-time constant of 85 ms. Xenon (doubly charged ion: m/z 68) and carbon dioxide (doubly charged ion: m/z 22) were monitored alternately at 75 ms intervals. Our experience with mass spectrometry has demonstrated the feasibility of using a compact dedicated instrument for accurately and non-invasively monitoring end-tidal xenon concentration in a clinical setting. PMID:6809066

Dhawan, V; Goldiner, P; Ray, C; Conti, J; Rottenberg, D A

1982-06-01

370

Deposition of diamond-like films from a high-velocity flow of a rarefied gas mixture  

NASA Astrophysics Data System (ADS)

In contrast to the widespread deposition method of carbon films with the activation of gas mixtures on a hot wire, activation (dissociation of hydrogen and methane) is performed in a high-temperature channel formed by a tungsten coil in this study. From this channel, the gas is expanded to the substrate where deposition occurs. A film containing diamond crystals and hexagonal crystals having characteristic features of lonsdaleite is deposited at the channel temperature of 2100°C and the surrounding pressure of 20 mmHg. The diamond-like film is deposited from a high-velocity high-temperature un-ionized flow for the first time.

Rebrov, A. K.; Emel'yanov, A. A.; Yudin, I. B.

2013-05-01

371

A Study on Coaxial Type DBD Decomposing NO\\/N2 Mixture Gas by Optical Emission Spectrum  

Microsoft Academic Search

Through establishing a test system of coaxial dielectric barrier discharge type non-thermal plasma reactor, using Q-V Lissajous figure method to measure its electrical parameters, optical emission spectrum of NO\\/N2 mixed gas system was analyzed, and the effects of the applied voltage peak-peak value(VP-P) on the optical emission spectrum intensity of NO, N2 excited state species were studied when NO\\/N2 mixture

Liu Zhinan; Cai Yixi; Wang Jun; Sun Chuanhong; Han Wenhe

2010-01-01

372

A particle-to-particle heat transfer model for dense gas–solid fluidized bed of binary mixture  

Microsoft Academic Search

A particle-to-particle collisional heat transfer model in the frame of Eulerian–Eulerian approach was proposed in this paper. By incorporating it into the multi-fluid model to close the enthalpy equations, the heat transfer between different particle classes in a gas bubbling fluidized bed of binary mixture was investigated, based on the CFD simulations of particle mixing in literature (Cooper and Coronella,

Jian Chang; Shuqing Yang; Kai Zhang

2011-01-01

373

High-temperature linear kinetics of FeS formation and reduction in COS-CO-CO 2 gas mixtures  

Microsoft Academic Search

The linear kinetics of the monosulfide scale formation and reduction according to the overall reaction Fe(s) + COS(g) = FeS(s) + CO(g) in COS-CO-CO2 gas mixtures was studied in the temperature range 750–910† C by a thermogravimetric technique. The validity of the linear rate law is limited to short times of exposure and relatively low partial pressures of COS. A

Steinar Haugen; Aasmund Sterten

1971-01-01

374

Modeling of a photolytically excited HF chemical laser based on a NF3\\/H2 gas mixture  

Microsoft Academic Search

A numerical code has been developed to simulate the characteristics of HF chemical laser based on non-chain reaction pumped by a planar sliding discharge radiation. The model considers transport of VUV pump radiation through the nonlinear absorptive active medium containing NF3\\/H2\\/N2\\/Ar gas mixture coupled with chemical and lasing kinetics describing the temporal and spatial evolution of particle species concentration and

M. P. Sabonnadiere; V. I. Tcheremiskine; Marc L. Sentis; L. D. Mikheev; Philippe C. Delaporte

1998-01-01

375

Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture  

DOEpatents

A method of and an apparatus for detecting and accurately measuring the mean concentrations of .sup.222 Rn and .sup.220 Tn in a gas mixture, such as the ambient atmosphere in a mine, is provided. The apparatus includes an alpha target member which defines at least one operative target surface and which is preferably fabricated from a single piece of an alpha particle sensitive material. At least one portion of the operative target surface is covered with an alpha particle filter. The uncovered and filter covered operative surface is exposed to the gas mixture containing the .sup.222 Rn and .sup.220 Tn. In the radioactive decay series of these isotopes the maximum kinetic energy emitted by the alpha decay of .sup.222 Rn is about 1.1 MeV less than the maximum kinetic energy emitted by the alpha decay of a .sup.220 Tn. The alpha particle filter has a predetermined mass per unit area of the covered portion of the operative target surface that prevents penetration of alpha particles which originate from .sup.222 Rn decay, but which allows passage therethrough of the maximum kinetic energy alpha particles from .sup.220 Tn decay. Thus, a count of the alpha particle tracks in the uncovered portion of the target member is proportional to the mean concentration of sum of .sup.222 Rn and .sup.220 Tn in the gas mixture, while the count of alpha tracks in the target member under the filter is proportional to the concentration of only the .sup.220 Tn in the gas mixture.

Lucas, Henry (P.O. Box 1454, Sedona, AZ 86336)

1990-01-01

376

Characterisation of the coke formed during metal dusting of iron in CO–H 2–H 2O gas mixtures  

Microsoft Academic Search

Carbon deposits formed on the surface of iron samples during carburisation at 700 °C in a gas mixture of 75%CO–24.81%H2–0.19%H2O were characterised by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Mössbauer spectroscopy and transmission electron microscopy (TEM). Cross-section observation of the iron sample by light optical microscopy revealed the formation of cementite after only 10 min reaction, together with

J Zhang; A Schneider; G Inden

2003-01-01

377

EFFECT OF DEGREE OF REACTION ON CRITICAL CONDITIONS AND TIMES TO IGNITION OF A GAS MIXTURE EXPLOSION  

Microsoft Academic Search

The effect of degree of reaction on critical conditions and times to ignition of a gas-mixture explosion is theoretically examined in detail. The Arrhenius form of the chemical kinetic rate and the Frank-Kamenetskii approximation for that form is considered. The study offers analytical and numerical solutions of the problem in pressure-time, temperature-time, and temperature-pressure planes. The analytical solution presented analytical

SAAD A. EL-SAYED

2006-01-01

378

Xenon porometry: a novel method for the derivation of pore size distributions.  

PubMed

Xenon porometry is a novel method used for characterizing porous materials by the (129)Xe nuclear magnetic resonance of xenon gas. With the method, the diffusion of gas is slowed down by immersing the material in a medium, which can be in liquid or solid state during measurements. Because of slow diffusion, the signal of a xenon atom is characteristic of the properties of only one pore, and the composite signal of all atoms represents the distribution of properties. The method is especially applicable for determining pore size distribution because the chemical shifts of two different xenon signals (one from liquid and the other from gas pockets in solid) are dependent on pore size. Therefore, the shapes of these signals represent pore size distribution function. In addition, the porosity of the material can be determined by comparing the intensities of two signals. This article focuses on describing xenon signals observed from gas pockets in a solid medium, which has turned out to be most convenient for pore size determination. PMID:17466763

Telkki, Ville-Veikko; Lounila, Juhani; Jokisaari, Jukka

2007-01-16

379

Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas  

NASA Astrophysics Data System (ADS)

The focusing characteristics of a ruthenium-coated cylindrical mirror were investigated on the basis of its ability to collect and focus broadband 5-17-nm soft X-rays emitted from a laser-produced plasma. Based on the plasmas spectral intensity distribution and the reflectivity function of the mirror, we defined the optimum position of the integrated cylindrical mirror at which the X-ray energy flux transported and focused through the mirror was maximum. A minimum spot diameter of 22 mm at a distance of approximately 200 mm from a soft X-ray source was confirmed. The maximum intensity of the collected soft X-rays was 1.3 mJ/cm2 at the center of the irradiation zone. Thus, the irradiation intensity was improved by approximately 27 times when compared to that of 47 ?J/cm2 without the mirror. The debris sputtering rate on the reflection surface of the mirror can be reduced to 1/110 by argon gas at 11 Pa, while the attenuation rate of the soft X-rays due to absorption by the buffer gas can be suppressed to less than 10% at the focal point. The focusing property of the mirror is expected to be maintained for 3000 h or longer without significant degradation for a 100 W/320 pps laser shot if the ruthenium layer is thicker than 10 ?m. These results suggest that a stand-alone broadband soft X-ray processing system can be realized by using laser-produced plasma soft X-rays.

Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro

2012-12-01

380

Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas  

SciTech Connect

The focusing characteristics of a ruthenium-coated cylindrical mirror were investigated on the basis of its ability to collect and focus broadband 5-17-nm soft X-rays emitted from a laser-produced plasma. Based on the plasmas spectral intensity distribution and the reflectivity function of the mirror, we defined the optimum position of the integrated cylindrical mirror at which the X-ray energy flux transported and focused through the mirror was maximum. A minimum spot diameter of 22 mm at a distance of approximately 200 mm from a soft X-ray source was confirmed. The maximum intensity of the collected soft X-rays was 1.3 mJ/cm{sup 2} at the center of the irradiation zone. Thus, the irradiation intensity was improved by approximately 27 times when compared to that of 47 {mu}J/cm{sup 2} without the mirror. The debris sputtering rate on the reflection surface of the mirror can be reduced to 1/110 by argon gas at 11 Pa, while the attenuation rate of the soft X-rays due to absorption by the buffer gas can be suppressed to less than 10% at the focal point. The focusing property of the mirror is expected to be maintained for 3000 h or longer without significant degradation for a 100 W/320 pps laser shot if the ruthenium layer is thicker than 10 {mu}m. These results suggest that a stand-alone broadband soft X-ray processing system can be realized by using laser-produced plasma soft X-rays.

Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Ako-gun, Hyogo 678-1205 (Japan)

2012-12-15

381

Global atmospheric change: Potential health effects of acid aerosol and oxidant gas mixtures  

Microsoft Academic Search

Inhalation toxicology experiments in whole animals have demonstrated a remarkable lack of toxicity of sulfuric acid in the form of respirable aerosols, especially in rats and nonhuman primates. Thus, much of the current experimental emphasis has shifted to the evaluation of the potential health effects of acid aerosols as components of mixtures. Rats have been concurrently exposed to mixtures of

1991-01-01

382

XXI. The formation of molecular aggregates in radon-gas mixtures containing polar molecules  

Microsoft Academic Search

By various methods gaseous mixtures containing radon and its decay products have been investigated for the presence of molecular aggregates. Since in every case studied aggregates were obtained when the mixture contained polar molecules, and since in no case were aggregates detected when only non-polar molecules were present, it would appear that polar molecules definitely favour and are possibly essential

E. L. Harrington; O. A. Gratias

1931-01-01

383

Effects of N2--O2 Gas Mixture Ratio on Microorganism Inactivation in Low-Pressure Surface Wave Plasma  

NASA Astrophysics Data System (ADS)

In this study, the effect of N2/O2 gas mixture ratio on low-pressure surface wave plasma inactivation of spore-forming bacteria was investigated. It was experimentally confirmed from the quadrupole mass spectrometry measurements that the spores were etched by atomic oxygen via converting the hydrogen atoms constituting microorganisms into H2O and the carbon into CO2. On the basis of results of plasma diagnostics by optical emission spectroscopy and the results of inactivation efficiency by colony-forming units and scanning electron microscope, we found that although there is the highest ultraviolet (UV) emission intensity in pure N2 plasma and the highest etching efficiency in 90% O2/10% N2 plasma, the inactivation rate of microorganisms was not so efficient. The best inactivation result was obtained in 30--80% O2 gas mixture ratios after 60 s plasma irradiation. The present results indicated that more efficient inactivation is achieved by the synergetic effects between atomic oxygen etching and the vacuum ultraviolet (VUV)/UV emission by combining both effects via optimizing N2/O2 gas mixture ratio.

Zhao, Ying; Ogino, Akihisa; Nagatsu, Masaaki

2011-08-01

384

Single-Well-Gas-Sparging Tests for Assessing the Feasibility of In-situ Aerobic Treatment of CAH Mixtures  

NASA Astrophysics Data System (ADS)

Single-well-gas-sparge tests were performed to assess the feasibility of in-situ aerobic cometabolism of chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethylene (TCE) and cis-1,2-dichloroethylene (c-DCE), using propane and methane as growth substrates. The tests were performed in the saturate zone at the McClellan Air Force Base, CA. The effectiveness of gas sparging to stimulate indigenous propane-utilizers or methane-utilizers was evaluated in standard monitoring wells. Transport characteristics of dissolved solutes [sulfur hexafluoride (SF6 or bromide (tracer), propane or methane (growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and dissolved oxygen], were evaluated by push-pull transport tests. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and SF6. The transport tests demonstrated that bromide and SF6 could be used as conservative tracers for biological activity tests and that little loss of the dissolved gaseous substrates prior to biostimulation occurred. The dissolved gases were also conservatively transported indicating negligible trapped gas was present in the aquifer prior to sparging. A series of gas-sparging biostimulation tests were performed by sparging propane-(or methane)-oxygen-argon-SF6 gas mixture at specific depth intervals using a "straddle" packer. Temporal groundwater samples were obtained from the injection well under natural gradient "drift" conditions. Biostimulation was demonstrated with repeated gas sparging tests where the time to deplete methane and propane concentrations decreased compared to SF6. Gas sparging activity tests were performed using the same procedures as the gas-sparging biostimulation tests, except that ethylene and propylene were included in the sparging gas mixtures. Propane (or methane) utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane- and methane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide as cometabolic by-products. The results confirmed the biostimulation of indigenous microorganisms with cometabolism ability. When acetylene was included in the sparge gas mixture, propane and methane utilization and ethylene and propylene transformation were effectively blocked, indicating monooxygenase enzymes were involved

Kim, Y.; Istok, J.; Semprini, L.

2002-12-01

385

A portable gamma-ray spectrometer using compressed xenon  

SciTech Connect

An ionization chamber using compressed xenon has been designed and built for gamma-ray spectrometry. The device is based on signal measurement from a parallel plate detector, with the gas enclosure constructed specifically for packaging into a portable instrument; thus, appropriate engineering practices comprises two small containers that can be setup for operation in just a few minutes. Its sensitivity is 100 keV to over 1 MeV, with a resolution at 662 keV of 2.5% FWHM for uniform irradiation, and 2% FWHM for collimated irradiation, comparable to the best ever with compressed xenon. It also exhibits greater specificity that most scintillators, such as NaI. The device is insensitive to neutron damage and has a low power requirement.

Mahler, G.J.; Yu, B.; Smith, G.C.; Kane, W.R.; Lemley, J.R.

1997-10-01

386

Xenon NMR measurements of permeability and tortuosity in reservoir rocks.  

PubMed

In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores. PMID:15833638

Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

2005-02-01

387

ANALYTICAL METHOD FOR MEASURING TOTAL PROTIUM AND TOTAL DEUTERIUM IN A GAS MIXTURE CONTAINING H2, D2,AND HD VIA GAS CHAROMATOGRAPHY  

SciTech Connect

The most common analytical method of identifying and quantifying non-radioactive isotopic species of hydrogen is mass spectrometry. A low mass, high resolution mass spectrometer with adequate sensitivity and stability to identify and quantify hydrogen isotopes in the low ppm range is an expensive, complex instrument. A new analytical technique has been developed that measures both total protium (H) and total deuterium (D) in a gas mixture containing H{sub 2}, D{sub 2}, and HD using an inexpensive micro gas chromatograph (GC) with two molecular sieve columns. One column uses D{sub 2} as the carrier gas and the other uses H{sub 2} as the carrier gas. Laboratory tests have shown that when used in this configuration the GC can measure both total protium and total deuterium each with a detection and quantification limit of less than 20 ppm.

Sessions, H

2007-08-07

388

Preliminary Results for Capture of Negative Muons and Antiprotons by Noble-Gas Atoms  

Microsoft Academic Search

Cross sections for capture of negative muons (??) and antiprotons (\\u000a $${\\\\bar p}$$\\u000a ) by helium, neon, argon, krypton, and xenon atoms (incomplete for the two heaviest noble-gas atoms) are calculated using\\u000a the fermion molecular dynamics (FMD) method. These cross sections are used to estimate the capture ratios in mixtures, but\\u000a these ratios are not precise since the total energy-loss

James S. Cohen

2001-01-01

389

Preliminary Results for Capture of Negative Muons and Antiprotons by Noble-Gas Atoms  

NASA Astrophysics Data System (ADS)

Cross sections for capture of negative muons (?-) and antiprotons ({bar p}) by helium, neon, argon, krypton, and xenon atoms (incomplete for the two heaviest noble-gas atoms) are calculated using the fermion molecular dynamics (FMD) method. These cross sections are used to estimate the capture ratios in mixtures, but these ratios are not precise since the total energy-loss cross sections have not yet been determined.

Cohen, James S.

2001-12-01

390

Probing the effects of surfactant monolayers on gas- liquid collisions: Scattering studies of argon and xenon atoms striking dilute bismuth:gallium alloys  

NASA Astrophysics Data System (ADS)

Atomic beam scattering experiments are used to determine the ways in which surfactant Bi atoms alter energy transfer and scattering direction in collisions between Ar and Xe atoms and two dilute Bi:Ga alloys (0.02 and 0.2 atom% Bi in Ga). The Bi surface coverage of the dilute Bi:Ga solutions is measured with Auger Electron Spectroscopy (AES) and ranges from <1% at 673 K (0.02% Bi:Ga) to 98% at 313 K (0.2% Bi:Ga) of a Bi monolayer. The atomic beam scattering experiments show that surface Bi atoms reduce gas-liquid energy transfer between 92 kJ/mol Ar and 190 kJ/mol Xe atoms and the dilute alloys. The energy transfers take on pure Bi-like values at high Bi surface coverages, pure Ga-like values at low Bi surface coverages, and increase smoothly between the extremes of Bi-rich and Ga-rich surfaces. Surface Bi atoms are less effective at inhibiting Ar and Xe energy transfer when the incident energies of the gases are lowered (at incident energies of <30 kJ/mol for Ar and <75 kJ/mol for Xe). The effect of surface Bi atoms on the atomic-scale corrugation of the Bi, Ga, and Bi:Ga surfaces is investigated by measuring the Ar and Xe scattering intensity at ?inc = ? fin = 55° as a function of liquid temperature. The scattering intensities suggest that pure Ga presents a smoother liquid surface than either pure Bi or the low temperature (monolayer covered) alloy and that raising the temperature of the pure liquids increases surface roughness. The Ar and Xe intensities from the dilute Bi:Ga alloys suggest that the alloy surface is initially roughened as the temperature is increased but then becomes smoother at higher temperatures as surface Bi atoms are replaced with Ga atoms.

Morgan, Jason Aaron

391

Development of Partial Pressure Gauge for Silane-Hydrogen Gas Mixtures Used for Production of Thin Film Silicon Solar Cell Materials  

NASA Astrophysics Data System (ADS)

A partial pressure gauge was developed with a quartz sensor to measure partial pressures of silane and hydrogen gases in gas mixtures, which are used as the sources of thin film silicon solar cells. The partial pressures were derived from the dependencies on viscosity and molecular weight of these mixtures, which can be measured using the quartz sensor. The partial pressure gauge developed based on this principle measured partial pressures of silane and hydrogen in gas mixtures for 133-1,333 Pa and 0, 20, 40, 60, 80, and 100vol.% silane with resolution of 0.01vol.% for gas mixtures including over 20% silane partial pressures, which are typical preparation conditions for thin film silicon solar cell materials. This pressure gauge can be used in practical application to measure the partial pressures of silane and hydrogen in mixtures.

Suzuki, Atsushi; Kurokawa, Akira; Nagai, Takehiko; Matsui, Takuya; Kondo, Michio

392

Role of chemical kinetics on the detonation properties of hydrogen \\/natural gas\\/air mixtures  

Microsoft Academic Search

The first part of the present work is to validate a detailed kinetic mechanism for the oxidation of hydrogen–methane–air mixtures in detonation waves. A series of experiments on auto-ignition delay times have been performed by shock tube technique coupled with emission spectrometry for H2\\/CH4\\/O2 mixtures highly diluted in argon. The CH4\\/H2 ratio was varied from 0 to 4 and the

N. Chaumeix; S. Pichon; F. Lafosse; C.-E. Paillard

2007-01-01

393

Stability conditions of argon and helium gas mixtures in an atmospheric pressure plasma jet  

Microsoft Academic Search

Non-equilibrium plasmas can be generated by atmospheric pressure glow discharges, amongst others by atmospheric pressure plasma jets (APPJ), which feature a capacitive radio-frequency discharge between bare metallic electrodes.We investigated the stability conditions for discharges in an APPJ operated with helium–argon mixtures. Uniform ?-discharges can be sustained in mixtures ranging from pure helium to pure argon. The ignition voltage increases drastically

S. Haslinger; J. Laimer; H. Störi

2007-01-01

394

Isotopic fractionation during subsurface xenon transport after a below ground nuclear test  

NASA Astrophysics Data System (ADS)

Xenon transport through porous systems is critical to predicting how this gas will enter the atmosphere after a below ground nuclear weapons test. The ratio of specific xenon isotopes is used as a marker for determining whether test a has been conducted. It has generally been assumed that time is the only factor affecting the isotopic rations. Using a barometric cycling model, we show that gas transport itself can affect the ratios and cause them to drift outside the bounds that are used to establish whether a test has taken place.

Deinert, M. R.

2011-12-01

395

Negative pion capture in HD gas and in H2+D2 gas mixtures: Resolution of the isotope puzzle  

NASA Astrophysics Data System (ADS)

The cross sections, initial quantum numbers, and kinetic energies for pionic atoms formed by negative pion capture in mixtures of isotopic hydrogen molecules are calculated using the fermion-molecular-dynamics (FMD) method. With these cross sections, the reduced capture ratio for a H2+D2 mixture is found to be (P(H2+D2)p/P(H2+D2)d)/(cp/cd)=1.204, and the capture ratio for HD is found to be P(HD)p/P(HD)d=0.875. In light of these results, the p-to-d pion transfer probabilities Q are reevaluated using prior experimental data and determined to be larger than previously thought: Q=0.28 at deuterium fraction cd=0.5 and Q=0.42 as cd-->1. The puzzling relationship of the experimental data for HD to that for H2+D2 mixtures is explained.

Cohen, James S.

1999-06-01

396

Weird muonium diffusion in solid xenon  

Microsoft Academic Search

Muon and muonium spin rotation and relaxation parameters were studied in liquid and solid xenon. The small diamagnetic fraction (~10%) observed in condensed xenon is believed to be Xemu+. The muonium hyperfine frequency was measured for the first time in liquid Xe and was found to be in agreement with the vacuum value. A nonmonotonic temperature dependence of the muonium

V. G. Storchak; B. F. Kirillov; A. V. Pirogov; V. A. Duginov; V. G. Grebinnik; T. N. Mamedov; V. G. Ol'Shevsky; V. A. Xhukov; J. H. Brewer; G. D. Morris

1992-01-01

397

Xenon and Krypton in the Bruderheim Meteorite  

Microsoft Academic Search

In a series of heating experiments, xenon, radiogenic XeR, and krypton con- tents, and the xenon and krypton isotopic composition of the Bruderheim meteorite were studied for the separated minerals feldspar, pyroxene, olivine, and trollire and for numerous chondrule fractions. Important differences among the individual minerals and between min- erals and chondrules were observed, and the following conclusions were reached:

Craig Merrihue

1966-01-01

398

Results from the XENON1T Demonstrator  

NASA Astrophysics Data System (ADS)

The current stage of the XENON Dark Matter Search project, XENON100, constitutes one of the best performing dark matter experiments in the world, setting the best upper limit on the cross section for spin independent WIMP-nucleus scattering. The next generation detector within the program, XENON1T, is at the end of its design phase and construction will start in the present year. XENON1T is a liquid xenon dual-phase time projection chamber with a 1 Ton fiducial mass, and it will improve the present XENON100 limit by 2 orders of magnitude. However, the increase in mass in the new detector presents several technological challenges. In order to address the required improvements, a fully operational prototype of the detector, the XENON1T Demonstrator, has been built at Columbia University. In this talk we will present the main results of the XENON1T Demonstrator R&D program, comprising high-speed recirculation on a full-scale cryogenic system, the observation of electron drift over 30 cm, and the operation of the detector with a cathode high voltage exceeding 30kV and preliminary results of the new 60 and 100 cm setups.

Contreras, Hugo; Aprile, Elena; Budnik, Ranny; Goetzke, Luke; Plante, Guillaume; Messina, Marcello; Rizzo, Alfio; Melgarejo, Antonio; Naganoma, Junji; Chaguine, Petr

2013-04-01

399

Removal of particle matter from dust-vapor-gas mixture in condenser with inclined tubes  

NASA Astrophysics Data System (ADS)

The article presents results of the research of particulate matter and droplets removal on inclined tubes of the flue gas cleaning condenser in the process of vapor condensation of vapor-and-gas emissions from kraft pulp production.

Romanova, L. V.; Gogonin, I. I.

2012-03-01

400

Hydraulic Jet Flow of an Ideal Liquid and Gas-Liquid Mixtures.  

National Technical Information Service (NTIS)

The report contains articles on the performance of a reaction engine with an ejector shroud, the numerical solution to the problem of cooling a hot gas bubble in liquid, and the theory of gas-hydraulic propulsion engines.

G. V. Logvinovich V. M. Ivchenko I. M. Chernyi

1972-01-01

401

Release of Gas from Heated Oil Shale and from Mixtures of Dolomite and Quartz.  

National Technical Information Service (NTIS)

Experiments and calculations were performed to determine the amount of gas released from heated oil shale. It is known that kerogen, a component of oil shale, releases gas when heated. When the temperature is increased, the kerogen yields not only gas but...

R. W. Taylor

1976-01-01

402

On the analysis of CO 2 , H 2 - and CO, H 2 -mixtures by water-gas potentiometry with solid electrolyte cells  

Microsoft Academic Search

The potentiometric analysis of CO2, H2 and CO, H2O-mixtures using oxide ion-conducting solid electrolytes requires the adjustment of the water-gas equilibrium without side\\u000a reactions in the high-temperature galvanic cell. Conventional cell designs suitable for the analysis of H2, H2O and CO, CO2-mixtures are not applicable due to the insufficient gas residence times in the cells and the insufficient catalytical activity

Reinhold Hartung

1996-01-01

403

Corrosion behavior of Fe20Cr and Ni20Cr alloys in Ar-H[sub 2]O-HBr gas mixtures at 1000 K  

Microsoft Academic Search

Discontinuous mass-change measurements and corrosion-product analyses were made for Fe-20Cr and Ni-20Cr alloys after exposing them to Ar-H[sub 2]O-HBr gas mixtures at 1000 K for 24 hours. Predominantly chromia scales formed on both alloys. Upon cooling, the scales remained adherent to the Fe-20Cr alloy but spalled extensively from Ni-20Cr samples. After tests in HBr-rich gas mixtures, bromine-rich corrosion products were

B. Oenay; Yasutoshi Saito

1993-01-01

404

Corrosion behavior of Fe20Cr and Ni20Cr alloys in Ar-H 2 O-HBr gas mixtures at 1000 K  

Microsoft Academic Search

Discontinuous mass-change measurements and corrosion-product analyses were made for Fe-20Cr and Ni-20Cr alloys after exposing them to Ar-H2O-HBr gas mixtures at 1000 K for 24 hours. Predominantly chromia scales formed on both alloys. Upon cooling, the scales remained adherent to the Fe-20Cr alloy but spalled extensively from Ni-20Cr samples. After tests in HBr-rich gas mixtures, bromine-rich corrosion products were found

Bülent Önay; Yasutoshi Saito

1993-01-01

405

Determination of the average ionization and thermodynamic regimes of xenon plasmas with an application to the characterization of blast waves launched in xenon clusters  

NASA Astrophysics Data System (ADS)

Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shock propagates. In this work the average ionization and the thermodynamic regimes of xenon plasmas are determined as functions of the matter density and temperature in a wide range of plasma conditions. The results obtained will be applied to characterize blast waves launched in xenon clusters.

Rodriguez, R.; Gil, J. M.; Florido, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

2011-06-01

406

Extended photoionization calculations for xenon  

NASA Astrophysics Data System (ADS)

Partial photoionization cross sections and angular distribution asymmetry parameters for atomic xenon have been calculated in the relativistic random-phase approximation for 26 jj-coupled channels over a wide range of energies (0-1 keV). The effects of relaxation on the 4d and 3d cross sections are examined by using a modification of the relativistic random-phase approximation that calculates excited-state orbitals in the potential of the relaxed ion. Results are compared with Hartree-Fock theory, with the nonrelativistic random-phase approximation, and with recent photoemission experiments.

Kutzner, M.; Radojevi?, V.; Kelly, H. P.

1989-11-01

407

Optimization of the microstrip gas counter  

NASA Astrophysics Data System (ADS)

A study to optimize the characteristics of the microstrip gas counter for use as a tracker at the Large Hadron Collider was made. It was found that two of the most important design parameters of the detector are given by the choice of the counter gas and the width of the gas gap. Using measurements with an ultraviolet laser and a particle beam, two most suited mixtures for the counter gas were found, which consist of xenon, dimethylether and CO2. The optimum width of the gas gap was derived. It was found that when a high drift field is chosen in combination with a narrow gas gap, a reliable event tagging can be expected while the resolution still remains at a high level.

Geijberts, M. H. J.; Hartjes, F. G.; Pannekoek, J. G.; Schmitz, J.; Udo, F.

1991-08-01

408

Gas dynamic aspects of silicon thin layers deposition using excitation of a free jet of the working gas mixture by an electron beam  

SciTech Connect

A film of microcrystalline silicon ({mu}c-Si:H) deposited at low temperature is a promising material for thin-film silicon solar cells with high efficiency and high stability. To deposit silicon thin films with high deposition rate and high quality, a novel gas-jet deposition method has been developed. The paper is devoted to experimental and numerical study of the method from the gas dynamic point of view. A numerical model of the flow field of the working gas mixture in the device was developed that provides predictions of the film thickness distribution over the substrate surface and was found to describe the measured data satisfactory. The model may be used to optimize the operating parameters of the device.

Skovorodko, P. A.; Sharafutdinov, R. G.; Shchukin, V. G.; Konstantinov, V. O. [CJSC Institute of Plasma Chemical Technologies, 630090, Novosibirsk (Russian Federation) and Kutateladze Institute of Thermophysics, 630090, Novosibirsk (Russian Federation)

2012-11-27

409

Analysis of the insulation characteristics of c-C4F8 and N2 gas mixtures by Boltzmann equation method  

NASA Astrophysics Data System (ADS)

The present paper concerns itself with the insulation characteristics of c-C4F8/N2 gas mixtures and studies the possibility of applying in the gas insulation of power equipments. We aim to use the theoretical framework of the Boltzmann equation to calculate the density-normalized effective ionization coefficients (?-?)/N and transport parameters of c-C4F8/N2 gas mixtures for E/N values from 180 to 550 Td (1 Td = 10-17 V cm2) in the condition of steady-state Townsend (SST) experiment. From the variation curve of (?-?)/N with the c-C4F8 mixture ratio k, the limiting field strength (E/N)lim of the gas mixtures at different gas content is determined. In order to confirm the validity of the results obtained, comparisons with Monte Carlo simulation and experimental data have been performed. It is found that the insulation properties of c-C4F8 and N2 gas mixtures are much better than those of SF6 and N2 mixtures for applying in the high voltage apparatus as an insulation medium, especially if we take the global warming potential into account.

Deng, Y. K.; Xiao, D. M.

2012-02-01

410

Laser flash-photolysis and gas discharge in N2O-containing mixture: kinetic mechanism  

NASA Astrophysics Data System (ADS)

The paper is devoted to further experimental and theoretical analysis of ignition by ArF laser flash-photolysis and nanosecond discharge in N2O-containing mixture has been done. Additional experiments have been made to assure that laser emission is distributed uniformly throughout the cross-section. The series of experiments was proposed and carried out to check validity of O(^1D) determination in experiments on plasma assisted ignition initiated by flash-photolysis. In these experiments, ozone density in the given mixture (mixture composition and kinetics has been preliminary analyzed) was measured using UV light absorption in Hartley band. Good coincidence between experimental data and results of calculations have been obtained Temporal behavior of energy input, electric field and electric current has been measured and analyzed. These data are considered as initial conditions for numerical modeling of the discharge in O2:N2O:H2:Ar = 0.3:1:3:5 mixture. Ion-molecular reactions and reactions of active species production in Ar:H2:O2:N2O mixture were analyzed. The set of reactions to describe chemical transformation in the system due to the discharge action has been selected.

Kosarev, Ilya; Popov, Nikolay; Starikovskaia, Svetlana; Starikovskiy, Andrey

2011-11-01

411

Surface tension, coexistence curve, and vapor pressure of binary liquid-gas mixtures  

SciTech Connect

The objective of this paper is to present measurements of the vapor pressure, capillary coefficient, and refractive index of four binary mixtures, CO/sub 2/-SF/sub 6/, R14-SF/sub 6/, SF/sub 6/-R13B1, and SF/sub 6/-R22, at liquid-vapor equilibrium at different average concentrations. The measuring temperature range covered the entire liquid-vapor region from the triple line up to the critical point. The capillary coefficient was determined by means of the capillary rise method; the refractive index, by measuring the angle of refraction of a light beam passing through a prism and the sample. In order to obtain the liquid-vapor densities of pure substances the Lorentz-Lorenz relation can be used. However, in applying this relation to calculate the liquid-vapor densities of a mixture, one may need the concentrations of both the liquid and the vapor phase, which are, for the most part, quite different from the average concentration of the mixture. Calculating the concentrations of both fluid phases with the aid of an equation of state and comparing with measurements, we could show that the molar refraction coefficient of the mixtures can be simply determined from the average concentration and the molar refraction coefficients of their pure components. The surface tension of the mixtures could then be calculated from the measured capillary coefficient and the refractive index with the aid of the Lorentz-Lorenz relation.

Do, V.T.; Straob, J.; Hanley, H.J.M.; Cezairliyan, A.

1986-01-01

412

Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons  

SciTech Connect

Phase equilibrium in mixtures of water + light gases and water + heavy hydrocarbons has been investigated with the development of new local composition theory, new equations of state, and new experimental data. The preferential segregation and orientation of molecules due to different energies of molecular interaction has been simulated with square well molecules. Extensive simulation has been made for pure square well fluids and mixtures to find the local composition at wide ranges of states. A theory of local composition has been developed and an equation of state has been obtained for square well fluids. The new local composition theory has been embedded in several equations of state. The pressure of water is decoupled into a polar pressure and non-polar pressure according to the molecular model of water of Jorgensen et al. The polar pressure of water is combined with the BACK equation for the general description of polar fluids and their mixtures. Being derived from the steam table, the Augmented BACK equation is particularly suited for mixtures of water + non-polar substances such as the hydrocarbons. The hydrophobic character of the hydrocarbons had made their mixtures with water a special challenge. A new group contribution equation of state is developed to describe phase equilibrium and volumetric behavior of fluids while requiring only to know the molecular structure of the components. 15 refs., 1 fig.

Chao, K.C.

1990-01-01

413

Selective Adsorption of CO2 from Light Gas Mixtures Using a Structurally Dynamic Porous Coordination Polymer**  

SciTech Connect

The selective adsorption of CO{sub 2} from mixtures with N{sub 2}, CH{sub 4}, and N{sub 2}O in a dynamic porous coordination polymer (see monomer structure) was evaluated by ATR-FTIR spectroscopy, GC, and SANS. All three techniques indicate highly selective adsorption of CO{sub 2} from CO{sub 2}/CH{sub 4} and CO{sub 2}/N{sub 2} mixtures at 30 C, with no selectivity observed for the CO{sub 2}/N{sub 2}O system.

Kristi L. Kauffman, Jeffrey T. Culp, Andrew J. Allen, Laura Espinal, Winnie Wong-Ng, Thomas D. Brown, Angela Goodman, Mark P. Bernardo, Russel J. Pancoast, Danielle Chirdon, Christopher Matranga*

2010-01-01

414

Calculation of the thermodynamic properties of gas and liquid solutions - Multicomponent mixtures  

NASA Astrophysics Data System (ADS)

A method for calculating thermodynamic properties using a unified equation of state for gases and liquids in combination with an effective intermolecular potential is extended to multicomponent systems. A comparison with experimental data indicates that, for a sufficiently large number of components, the properties of mixtures can be calculated from data on the pure components only. Results of calculations for several mixtures, including Ar-N2, Ar-CH4, N2-CH4, Ar-N2-CH4, and H2-N2-CO2-CO-CH4, are presented and compared with experimental data.

Kessel'Man, P. M.; Tkachenko, V. V.; Ugol'Nikov, A. P.

1989-08-01

415

Velocity slip and temperature jump coefficients for gaseous mixtures. I. Viscous slip coefficient  

Microsoft Academic Search

The viscous slip coefficient was calculated for binary gaseous mixtures on the basis of the McCormack kinetic model of the Boltzmann equation, which was solved by the discrete velocity method. The calculations were carried out for the three mixtures of noble gases: neon-argon, helium-argon, and helium-xenon. It was showed that for the mixture of helium and xenon, which has a

Felix Sharipov; Denize Kalempa

2003-01-01

416

Viscoelastiticy and shear thinning near the critical point of xenon  

NASA Astrophysics Data System (ADS)

The critical point is the exact combination of pressure and temperature at which a fluid is balanced between the states of liquid and gas. Everyday experience gives no hint of the unusual nature of the critical point because familiar fluids such as air and water are far from their critical temperatures. Understanding the critical point is essential for an understanding of fluids in general because the near-critical behavior is universal. Properly scaled, fluids as dissimilar as air and water have near-critical thermodynamic properties (e.g. heat capacity) and transport properties (e.g. viscosity) that are similar. Sufficiently close to the critical point, theory predicts the similarities to be exact. This talk will describe two measurements of the viscosity of xenon that were made very close (<1 mK) to xenon's critical point (289 K, 5.8 MPa). The first experiment measured the viscosity increase caused by near-critical conditions. It revealed that, close to the critical point, xenon is partly elastic: It can stretch as well as flow. The second experiment, planned for July 2002, will look for the shear-rate-induced viscosity decrease predicted by theory. Such "viscoelasticity" and "shear-thinning" are ordinarily seen only in much more complicated fluids such as polymer solutions. Slowly relaxing fluctuations cause both phenomena. The first experiment found that the time scale for viscoelasticity was 2.0 times slower than predicted. Preliminary results for shear thinning from the second experiment will be reported. Both experiments were designed to operate in the microgravity provided by the Space Shuttle. We required microgravity because Earth's gravity compresses any fluid near its critical point. Near its critical point, a layer of xenon as thin as 1 mm collapses under its own weight until the density at the bottom is 8% greater than at the top. The density difference distorts the data. Conducting the experiments on the Space Shuttle reduces the density difference by a factor of 100.

Berg, R.; Yao, M.; Moldover, M.; Zimmerli, G.

417

Xenon Gamma Detector Project Support  

SciTech Connect

This project provided funding of $48,500 for part of one year to support the development of compressed xenon spectrometers at BNL. This report describes upgrades that were made to the existing detector system electronics during that period, as well as subsequent testing with check sources and Special Nuclear Materials. Previous testing of the equipment extended only up to the energy of 1.3 MeV, and did not include a spectrum of Pu-239. The new electronics allowed one-button activation of the high voltage ramp that was previously controlled by manual adjustments. Mechanical relays of the charging circuit were replaced by a tera-ohm resistor chain and an optical switch. The preamplifier and shaping amplifier were replaced by more modern custom designs. We found that the xenon purity had not been degraded since the chamber was filled 10 years earlier. The resulting spectra showed significantly better resolution than sodium iodide spectra, and could be analyzed quite effectively by methods using peak area templates.

Vanier,P.E.; Forman, L.

2008-04-01

418

High pressure xenon ionization detector  

DOEpatents

A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs.

Markey, J.K.

1989-11-14

419

Thermodynamic and molecular properties of gas hydrates from mixtures containing methane, argon, and krypton  

Microsoft Academic Search

Because hydrate formation in pipelines, processing operations, and reservoirs is generally undesirable, studies of gas-hydrate thermodynamics, particularly examinations of conditions where a second hydrate phase or a hydrocarbon-rich phase exists in addition to the water, hydrate, and gas phases, are important to the natural gas industry. In this study, analysts used experimental methane-krypton and methane-argon hydrate data to generate chemical-potential,

G. D. Holder; G. Corbin; K. D. Papadopoulos

1980-01-01

420

Sound waves in monodisperse gas-particle or vapour-droplet mixtures  

Microsoft Academic Search

A brief review of the relevant papers and an examination of the current status of research in the field of the acoustics of gas-particle suspensions are given. Nonstationary momentum, mass and energy transfer processes between a gas (vapor) and dispersed particles (droplets) under high-frequency acoustic perturbations are considered. A comparative evaluation of characteristic times and temperature differences for gas-particle and

N. A. Gumerov; A. I. Ivandaev; R. I. Nigmatulin

1988-01-01

421

High-rate reactive ion etching of barium hexaferrite films using optimal CHF3/SF6 gas mixtures  

NASA Astrophysics Data System (ADS)

The high-rate reactive ion etching of c-axis oriented quasi-single-crystal barium hexaferrite (BaM) films, deposited on 6-H silicon carbide (0001) substrates, has been demonstrated. Arrays of BaM columns, having diameters of 1-4 ?m and sharp vertical walls, were etched from BaM films at rates as high as 75 nm/min using an optimized sulfur hexafluoride and methyl trifluoride (SF6:CHF3, 3:1) gas mixture. Lateral features as small as 43 nm were fabricated and imaged.

Chen, Zhaohui; Yang, Aria; Xie, Changqing; Yang, Qinghua; Vittoria, C.; Harris, V. G.

2009-03-01

422

Modeling of a photolytically excited HF chemical laser based on a NF3/H2 gas mixture  

NASA Astrophysics Data System (ADS)

A numerical code has been developed to simulate the characteristics of HF chemical laser based on non-chain reaction pumped by a planar sliding discharge radiation. The model considers transport of VUV pump radiation through the nonlinear absorptive active medium containing NF3/H2/N2/Ar gas mixture coupled with chemical and lasing kinetics describing the temporal and spatial evolution of particle species concentration and intracavity lasing photons density. The relative importance of various kinetic processes is evaluated and a 3.2 J/l laser output specific energy is calculated along the laser axis.

Sabonnadiere, M. P.; Tcheremiskine, V. I.; Sentis, Marc L.; Mikheev, L. D.; Delaporte, Philippe C.

1998-12-01

423

On the Equipartition of Kinetic Energy in an Ideal Gas Mixture  

ERIC Educational Resources Information Center

|A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)|

Peliti, L.

2007-01-01

424

MEASUREMENT AND CORRELATION OF GAS-LIQUID EQUILIBRIA IN MIXTURES OF LIGHT GASES AND HEAVY HYDROCARBONS  

Microsoft Academic Search

Because of increased interest in coal conversion processes there is a growing need for basic information on the vapor-liquid equilibria of mixtures containing light non-condensable gases and heavy aromatic hydrocarbons found in coal derived liquids. These phase equilibrium data are required at the elevated temperatures and pressures at which most coal conversion processes will be run.^ In this work we

HERBERT M SEBASTIAN

1980-01-01

425

[Thermodynamics of the state of a multicomponent CO2-CO-H2O-H2-N2 gas mixture in an electrolyzer with a solid electrolyte].  

PubMed

The thermodynamic state of the gas mixture CO2 = CO = H2O = H2 = N2 in the cathode space of the electrolyzer containing a solid electrolyte is investigated. Calculation of the thermodynamic state makes it possible to determine the theoretical voltage of decomposition and concentration of individual components of this mixture at the outlet of the electrolyzer or each electrolytic cell as applied to various modes of operation. Knowledge of these parameters is important to build a technological scheme of a gas mixture regeneration system. Equations of four independent reactions are used to describe thermodynamic equilibrium reactions are used to describe thermodynamic equilibrium of the gas mixture. Particular cases that occur, when one, two or more conditions of the technological process are not satisfied, are considered. PMID:3104662

Grishaenkov, B G; Zorina, N G

426

Inert Gas Purification and Measuring Oxygen Partial Pressure in Gas Mixtures with EMF Method Based on Solid Electrolyte Cell.  

National Technical Information Service (NTIS)

Inert atmospheres are often needed in metallurgical and chemical high-temperature experiments to prevent the sample from undesired reactions such as oxidation. Argon gas is readily available and thus the most commonly used medium for this purpose, so the ...

I. Isomaeki

1994-01-01

427

Polymer coated quartz crystal microbalance sensors for detection of volatile organic compounds in gas mixtures  

Microsoft Academic Search

By coating different conducting polymers of thiophene and its derivatives on quartz crystal microbalance (QCM) sensor surfaces, new novel QCM gas sensors have been produced in two simple ways, which could classify testing gas samples of volatile organic compounds (VOCs) gases. Principle components analysis (PCA) has been performed based on the QCM measurement results, which shows that our QCM sensors

Pengchao Si; John Mortensen; Alexei Komolov; Jens Denborg; Preben Juul Møller

2007-01-01

428

Separation of Carbon Dioxide from Natural Gas Mixtures through Polymeric Membranes—A Review  

Microsoft Academic Search

Various technologies are now available to design engineers to condition raw natural gas to pipeline quality. Conditioning of natural gas involves the removal of acid gases like CO2 and H2S, besides water vapor. Among different separation methods available, membrane technology has emerged to be a viable and valuable option over conventional techniques like amine absorption, in view of its advantages

S. Sridhar; B. Smitha; T. M. Aminabhavi

2007-01-01

429

Particle-initiated breakdown with spacer involvement in compressed gas and its mixtures  

Microsoft Academic Search

The use of compressed gas as the insulating medium has made it possible to use compact equipment compared to that with air insulation. However, the compact construction increases the operating field intensity. Sulphur hexafluoride (SF6) gas insulation is extremely sensitive to local increases in electric field, which results from protrusion on electrode, triple junction (the region where the electrode, insulator

M. M. Morcos; S. A. Ward; H. Anis

1999-01-01

430

A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits  

USGS Publications Warehouse

This report presents a model that calculates flow properties (pressure, vesicularity, and some 35 other parameters) as a function of vertical position within a volcanic conduit during a steady-state eruption. The model idealizes the magma-gas mixture as a single homogeneousfluid and calculates gas exsolution under the assumption of equilibrium conditions. These are the same assumptions on which classic conduit models (e.g. Wilson and Head, 1981) have been based. They are most appropriate when applied to eruptions of rapidly ascending magma (basaltic lava-fountain eruptions, and Plinian or sub-Plinian eruptions of intermediate or silicic magmas) that contains abundant nucleation sites (microlites, for example) for bubble growth. -- Mastin and Ghiorso, 2000

Mastin, L. G.; Ghiorso, M. S.

2000-01-01

431

Measurement of Binary Diffusion Coefficients for Neon-Argon Gas Mixtures Using a Loschmidt Cell Combined with Holographic Interferometry  

NASA Astrophysics Data System (ADS)

The paper reports on experimental binary diffusion coefficient data of neon-argon gas mixtures. Measurements were performed in the temperature range between 293.15 K and 333.15 K and for pressures between 1 bar and 10 bar over almost the whole composition range using a Loschmidt diffusion cell combined with holographic interferometry. The thermostated Loschmidt cell is divided into two half-cells, which can be separated and connected by a sliding plate. Prior to the measurements, two different pure gases are filled into the two half-cells. After starting the diffusion process, the temporal change of the partial molar densities, or rather of the refractive index of the gases, is detected in both half-cells using two holographic interferometers. With this apparatus, the temperature, pressure, and concentration dependence of the binary diffusion coefficient can be determined. The relative uncertainty of a diffusion measurement is between 0.4 % and 1.4 % depending on the pressure. The experimental data are compared with data from the literature and with new theoretical data based on quantum-mechanical ab initio calculations combined with the kinetic theory of gases. Due to a systematic error, the concentration dependence determined in the upper half-cell shows deviations from the theoretical values and from most of the literature data. The concentration, temperature, and pressure dependence obtained from the data from the lower half-cell, however, are in very good agreement with available data. The product of the binary gas diffusion coefficient and the molar density of the gas mixture shows no significant dependence on pressure for the studied neon-argon noble gas system.

Kugler, T.; Jäger, B.; Bich, E.; Rausch, M. H.; Fröba, A. P.

2013-01-01

432

RELAX-1, A Refrigerator Enhanced Laser Analyzer for Xenon  

NASA Astrophysics Data System (ADS)

A time-of-flight mass spectrometer with a resonance ionization source [1,2] and a cryogenic sample concentrator [3,4] which increases the efficiency of the spectrometer by two orders of magnitude, has been constructed for the isotopic analysis of xenon. In the two-photon excitation, one-photon ionization scheme employed, a wavelength of 249.6 nm excites the 2P(sub)3/26p[1/2](sub)0 level of xenon. A pulsed laser operating at 10 Hz, with a pulse duration of 8 ns and energy of 1.5 mJ is used. The sample concentrator consists of a localised cold spot (<90 K) onto which the xenon sample is condensed. The spot is heated by a Nd:YAG laser (25 mJ, 6 ns), evaporating the condensed sample gas into the ionizing region 1 us (chosen for optimum sensitivity) before the ionizing laser is fired. The mean return time to the cold spot is about 10 seconds in the 450-ml spectrometer and corresponds to an effective spot diameter of 1 mm. With each laser shot, 1% of the atoms released by the heating laser are ionized and, between shots, 1% of the sample recondenses onto the cold spot. Thus at 10 Hz, 1000 atoms produce a signal of 1 cps, which compares with a typical sensitivity of around 15,000 atoms/cps for conventional instruments. Since all isotopes are detected simultaneously, the effective sensitivity is more than two orders of magnitude greater than a single collector conventional instrument. Furthermore the background count rate due to multiplier dark current at a given mass is negligible (1 count per week) and the sole limitation on ultimate sample size is adsorbed xenon on the sample and the spectrometer walls. The velocity distribution of atoms leaving the cold finger has been determined by varying the delay between heating and ionizing lasers, and is Maxwellian with an angular dependence of the form cos^n(q) (n>5) and a characteristic temperature of 350 K. For sampled atoms of velocity v and characteristic temperature T, the theoretical instrumental discrimination [3] is 3/2m-1.66 x 10^27 v^2/2kT per mil per amu and is confirmed by experiment. Nonresonant ionization of hydrocarbons may occur at the high power densities necessary to saturate the two-photon transition of xenon (about 10^-9 Wcm^-2). Residual hydrocarbon effects in the spectrometer are monitored by detuning the wavelength of the ionizing laser away from resonance and are negligible. One side effect of the sample concentrator is that hydrocarbons tend to condense on parts of the cold spot the heating laser does not reach. Moreover most of the hydrocarbons that are evaporated leave the surface with velocities different from those of xenon and do not see the ionising laser beam. The spectrometer is currently being used to analyse xenon in meteorite residues and cosmogenic xenon in terrestrial barite. References 1. C H Chen, G S Hurst, M G Payne (1980) Chem. Phys. Lett. 75, 473-477. 2. J D Gilmour, S M Hewett, I C Lyon, M Stringer, G Turner (1991) Meas. Sci. Technol. 2, 589-595. 3. J D Gilmour, S M Hewett, I C Lyon, I Perera, G Turner, in prep. 4. G S Hurst, M G Payne, R C Phillips, J W T Dabbs, B E Lehmann (1984) J. Appl. Phys. 55, 1278-1284.

Gilmour, J. D.; Johnston, W. A.; Lyon, I. C.; Turner, G.

1992-07-01

433

The mechanism and kinetics of energy transfer processes in the Xe-CCl4-M (M=CH4, C2H2, C2H4, C2H6 C3H6 and C3H8) mixtures irradiated by xenon resonance light  

NASA Astrophysics Data System (ADS)

The mechanism and kinetics of energy transfer from Xe(6s[3/2]1) resonance state (E=8.44 eV) to selected hydrocarbon molecules have been investigated by XeCl(B-X) (?max=308 nm) fluorescence intensity measurements at stationary conditions in Xe-CCl4-M systems. Steady-state analysis of the fluorescence intensity dependence on the xenon and M pressure at constant CCl4 concentration shows that these process occur in the two- and three-body reactions: Xe(6s[3/2]10)+M-->products, Xe(6s[3/2]10+M+Xe-->products. The two- and three-body rate constants for these reactions have been found (see Table 1 ). It has been shown that the third order reaction is a very effective channel of energy transfer from xenon excited atoms to hydrocarbons at xenon pressures above 50 Torr in all investigated systems.

Wojciechowski, K.

1999-01-01

434

High energy low divergence electron beams generated with gas mixtures in sub-milimeter length gas cells  

NASA Astrophysics Data System (ADS)

Laser wakefield acceleration in underdense plasma has been an area of intense study as a source of high energy monoenergetic electron beams. In this work, we report on the acceleration of electrons with energies on the order of 100 MeV using sub millimeter gas cells with comparable lengths to the source's dephasing length. The gas cell design, used mainly to overcome the density inhomogeneity associated with gas jets, yielded low density homogeneous sub-millimeter length plasmas. A 50 fs, ˜10 TW Ti:Sapphire laser was focused with an OAP onto gas cells 300 ?m long. Helium was used as the target gas with N2 impurities added in order to induce ionization trapping of plasma electrons as previously reported [1]. The observed electron beams had divergences as low as 1.9 mrad and an unnormalized emittance as low as 3.7 x10-3 mm mrad. These results are to be presented and techniques to reduce energy spread to be explored.[4pt] [1] Pak, A., et. al. PRL, 104, 025003.

Shaw, Jessica; Vafaei-Najafabadi, Navid; Marsh, Ken; Joshi, Chan

2011-11-01

435

Composition of hydrofullerene mixtures produced by C(60) reaction with hydrogen gas revealed by high-resolution mass spectrometry.  

PubMed

Complex solid hydrofulleride mixtures were synthesized by prolonged hydrogenation of C(60) at 120 bar hydrogen pressure, 673 K temperature, and different reaction periods. The high degree of hydrogenation was confirmed by infrared spectroscopy and X-ray diffraction. The identity of hydrogenation products was determined by high-resolution field desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry. Despite partial gas-phase fragmentation of hydrofullerene ions during mass analysis, the data suggest that the synthesized mixtures consist of mostly C(58-60)H(x) hydrofullerenes. Increasing the duration of hydrogenation results in synthesis of C(59)H(x) and C(58)H(x) as major products. Possible hydrofullerene fragmentation pathways during both material synthesis and mass spectrometric analysis are discussed. Gas-phase fragmentation in the mass spectrometer arises from hydrofullerene ions C(60)H(x)(+) with x > 40 and C(59)H(44)(+) with drastically decreased molecular stability relative to the known C(60)H(36). PMID:16852579

Talyzin, Alexander V; Tsybin, Yury O; Schaub, Tanner M; Mauron, Philippe; Shulga, Yury M; Züttel, Andreas; Sundqvist, Bertil; Marshall, Alan G

2005-07-01

436

Gas Dynamic Features of Self Ignition of Non Diluted Fuel\\/Air Mixtures at High Pressure  

Microsoft Academic Search

– The self ignition of several non diluted fuel\\/air mixtures at high pressureis studied. Hydrogen,rsc-ocrane and n-heptane have been used as fuels. Experimentshave been performedusing the shock tube technique. Various observation methods, such as recording of pressure and of light band emission and shadow cinematography have been applied. The type of self ignition 35 well as the ignition delay times

R. BLUMENTHAL; K. FIEWEGER; K. H. KOMP; G. ADOMEIT

1997-01-01

437

Gas Dynamic Features of Self Ignition of Non Diluted Fuel\\/Air Mixtures at High Pressure  

Microsoft Academic Search

The self ignition of several non diluted fuel\\/air mixtures at high pressure is studied. Hydrogen, iso-octane and n-heptane have been used as fuels. Experiments have been performed using the shock tube technique. Various observation methods, such as recording of pressure and of light band emission and shadow cinematography have been applied. The type of self ignition as well as the

R. BLUMENTHAL; K. FIEWEGER; K. H. KOMP; G. ADOMEIT

1996-01-01

438

PILOT STUDY: International comparison CCQM-P41 Greenhouse gases. 2. Direct comparison of primary standard gas mixtures  

NASA Astrophysics Data System (ADS)

In this second part of this study, primary standard gas mixtures (PSMs) as used for calibrations for the greenhouse gases carbon dioxide and methane have been compared. The nominal amount-of-substance fraction levels were 365 µmol/mol for carbon dioxide and 1.8 µmol/mol for methane. The matrix was synthetic air, simulated by a mixture of nitrogen, oxygen (209 mmol/mol) and argon (9.3 mmol/mol). The measurements took place in the spring of 2003. In the protocol, it was foreseen to have the PSMs produced for this study in a small range, enabling regression analysis on the data to assess the consistency of the gas mixtures. The direct comparison of the PSMs shows agreement for carbon dioxide at 365 µmol/mol nominal within 0.52 µmol/mol (0.14% relative) standard uncertainty. One cylinder lies between the 95% and 99% boundaries of the regression line, and after removing this cylinder from the dataset the standard deviation of the x-residuals reduces to 0.18 µmol/mol (0.05% relative). This value for the standard deviation is substantially greater than the stated standard uncertainties for several cylinders. The standard deviation of the x-residuals for methane at 1.8 µmol/mol nominal is 0.011 µmol/mol. Main text. To reach the main text of this paper, click on Final Report. The final report has been peer-reviewed and approved for publication by the CCQM.

van der Veen, Adriaan M. H.; Brinkmann, Freek N. C.; Arnautovic, Mile; Besley, Laurie; Heine, Hans-Joachim; Lopez Esteban, Teresa; Sega, Michela; Kato, Kenji; Seog Kim, Jin; Perez Castorena, Alejandro; Rakowska, Agata; Milton, Martin J. T.; Guenther, Frank R.; Francey, R.; Dlugokencky, E.

2007-01-01

439

Direct simulation scheme derived from the Boltzmann equation. I - Monocomponent gases. II - Multicomponent gas mixtures. III - Rough sphere gases  

NASA Astrophysics Data System (ADS)

The stochastic expression which specifies the velocities of simulated molecules after a small time increment was derived from the Boltzmann equation. The molecule velocity determines the collision probability of the molecule without specifying its collision partner; if the molecule is accepted as a colliding entity, its collision partner is sampled from this probability distribution. The probability density provides the postcollision velocity of the molecule. An expression was also derived for the collision process in a simulation cell for a multicomponent gas mixture; the expression based on the Boltzmann equation is similar to that for a monocomponent gas. Computations indicate that this simulation model agrees with the exact solutions of the Boltzmann moment equations. An expression was also derived for collisions in a gas of rough sphere molecules for a spatially uniform gas: the expression determines the collision probability of a molecule, the probability distribution which prescribes the collision partner, the probability density which specifies the direction of the line-of-centers of the collision pair, and the postcollision values of the velocity of a molecule.

Nanbu, K.

1980-11-01

440

Comprehensive Two-Dimensional Gas Chromatography and Chemometrics for the Analysis of Complex Mixtures.  

National Technical Information Service (NTIS)

The main goal of this dissertation is to enhance the analysis capabilities of comprehensive two-dimensional (2-D) gas chromatography (GC x GC) by applying chemometrics to extract component signals in the presence of significant interference, noise, or bot...

C. G. Fraga

2000-01-01

441

Magic Numbers for Sphere Packings: Experimental Verification in Free Xenon Clusters  

Microsoft Academic Search

The existence of magic numbers for atomic microclusters has been found experimentally for the first time. The magic numbers n* manifest themselves in the mass spectra of free xenon clusters, nucleated in the gas phase. The observed numbers n*=13, 55, and 147 coincide with the numbers of spheres required for complete-shell icosahedra. The appearance of further magic numbers (19, 25,

O. Echt; K. Sattler; E. Recknagel

1981-01-01

442

Xenon-129 NMR study of the microporous structure of clays and pillared clays.  

National Technical Information Service (NTIS)

(sup 129)Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diam...

C. Tsiao K. A. Carrado

1990-01-01

443

Mechanism for transient migration of xenon in UO2  

NASA Astrophysics Data System (ADS)

In this letter, we report recent work on atomistic modeling of diffusion migration events of the fission gas product xenon in UO2 nuclear fuel. Under nonequilibrium conditions, Xe atoms can occupy the octahedral interstitial site, in contrast to the thermodynamically most stable uranium substitutional site. A transient migration mechanism involving Xe and two oxygen atoms is identified using basin constrained molecular dynamics employing a Buckingham type interatomic potential. This mechanism is then validated using density functional theory calculations using the nudged elastic band method. An overall reduction in the migration barrier of 1.6-2.7 eV is obtained compared to vacancy-mediated diffusion on the uranium sublattice.

Liu, X.-Y.; Uberuaga, B. P.; Andersson, D. A.; Stanek, C. R.; Sickafus, K. E.

2011-04-01

444

Microdischarges of xenon sustained by microwaves: Determination of scaling laws  

SciTech Connect

The threshold conditions to maintain millimeter and submillimeter-size discharges of xenon with microwaves are experimentally determined. The threshold electric field required to sustain the plasma is reported as a function of gas pressure. The influence of the size of the dielectric cell in which the discharge is produced is also shown. The scaling laws are deduced from the threshold electric field measurements, assuming a few additional simplifying assumptions. The results are compared with data obtained with argon discharges sustained by surface waves in capillary tubes and the hypotheses assumed for the calculations are discussed.

Lacoste, A.; Maulat, O.; Latrasse, L.; Arnal, Y.; Pelletier, J. [Laboratoire Elaboration par Procedes Magnetiques (EPM), UPR CNRS 9033 ENSHMG, BP 95, 38402 Saint Martin d'Heres Cedex (France)

2005-04-04

445

Xenon ion beam characterization in a helicon double layer thruster  

SciTech Connect

A current-free electric double layer is created in a helicon double layer thruster operating with xenon and compared to a recently developed theory. The Xe{sup +} ion beam formed by acceleration through the potential drop of the double layer is characterized radially using an electrostatic ion energy analyzer. For operating conditions of 500 W rf power, 0.07 mTorr gas pressure, and a maximum magnetic field of 125 G, the measured beam velocity is about 6 km s{sup -1}, the beam area is about 150 cm{sup 2}, and the measured beam divergence is less than 6 deg.

Charles, C.; Boswell, R. W.; Lieberman, M. A. [Space Plasma, Power, and Propulsion Group, Research School of Physical Sciences and Engineering, Australian National University, Australian Capital Territory 0200 (Australia)

2006-12-25

446

Measurements of laminar burning velocities for natural gas–hydrogen–air mixtures  

Microsoft Academic Search

Laminar flame characteristics of natural gas–hydrogen–air flames were studied in a constant-volume bomb at normal temperature and pressure. Laminar burning velocities and Markstein lengths were obtained at various ratios of hydrogen to natural gas (volume fraction from 0 to 100%) and equivalence ratios (? from 0.6 to 1.4). The influence of stretch rate on flame was also analyzed. The results

Zuohua Huang; Yong Zhang; Ke Zeng; Bing Liu; Qian Wang; Deming Jiang

2006-01-01

447

Heat capacity and thermal expansion of cryocystalline xenon at elevated temperatures  

NASA Astrophysics Data System (ADS)

The behavior of the heat capacity and thermal expansion of solid xenon (crystals of a rare gas) is studied in the range of elevated temperatures. It is found that the relative width of the premelting zone for xenon exceeds that for other solids. The Xe premelting parameters are estimated using the single-vacancy model. The results of this study explain the known difficulties encountered in the description of thermodynamic properties of solid inert gases using simple model potentials of the interatomic interaction of the Lennard-Jones type by the fact that premelting effects are not taken into account correctly.

Bodryakov, V. Yu.

2013-05-01

448

SAFE OPERATION OF NATURAL GAS APPLIANCES FUELED WITH HYDROGEN\\/NATURAL GAS MIXTURES (PROGRESS OBTAINED IN THE NATURALHY-PROJECT)  

Microsoft Academic Search

Considering the transition towards the hydrogen economy, dependent on hydrogen penetration scenario, the cost of a new hydrogen pipeline infrastructure in Europe may amount to several thousands of billions of EURO's. Therefore, the examination of the potential contribution of the existing natural gas assets is a practical and logical first step. As the physical and chemical properties of hydrogen differ

De Vries; O. Florisson; G. C. Tiekstra

449

Xenon worth calculations for plant operations  

SciTech Connect

Estimates of xenon worth for nonequilibrium operating histories based on calculations using a point model can be inaccurate due to the spatial distributions of the xenon and neutron flux. The magnitude of the misprediction can be as high as 700 pcm. This misprediction can lead to incorrect reactivity balance calculations for SDM surveillance and ECP calculations. The PC1D program uses a one-dimensional, two-group neutron diffusion model with a variable radial buckling correlation to accurately calculate xenon worth. Accuracy within 10 ppm can be expected for xenon worth calculations using the PC1D program. This will result in improved ECP and SDM surveillance calculations and in most cases will translate into reduced boron processing costs for the utility.

Leach, D.S.; Alsop, B.A..; Kapil, S.K.

1988-01-01

450

Analytical investigation of electrical breakdown properties in a nitrogen-SF{sub 6} mixture gas  

SciTech Connect

The electrical breakdown properties in nitrogen gas mixed with SF{sub 6} are analytically investigated in this article by making use of the ionization and attachment coefficients of the mixed gas. The ionization coefficients of nitrogen and SF{sub 6} gas are obtained in terms of the electron temperature T{sub e} by assuming a Maxwellian distribution of the electron energy. The attachment coefficient of SF{sub 6} gas is also obtained in terms of the gas temperature T{sub e}. An algebraic equation is obtained, relating explicitly the electron breakdown temperature T{sub b} in terms of the SF{sub 6} mole fraction {chi}. It was found from this equation that the breakdown temperature T{sub b} increases from approximately 2 to 5.3 eV as the mole fraction {chi} increases from zero to unity. The breakdown temperature T{sub b} of the electrons increases very rapidly from a small value and then approaches 5.3 eV slowly as the SF{sub 6} mole fraction increases from zero to unity. This indicates that even a small mole fraction of SF{sub 6} in the gas dominates the electron behavior in the breakdown system. The breakdown electric field E{sub b} derived is almost linearly proportional to the breakdown electron temperature T{sub b}. The experimental data agree remarkably well with the theoretical results. Therefore, it is concluded that even a small fraction of SF{sub 6} gas dominates nitrogen in determining the breakdown field. In this context, nearly 25% of the SF{sub 6} mole fraction provides a reasonable enhancement of the breakdown field for practical applications.

Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1, Wolgye-Dong, Nowon-Gu, Seoul 137-701 (Korea, Republic of); Byeon, Yong S.; Song, Ki B.; Choi, Eun H. [Department of Electrophysics, Kwangwoon University, 447-1, Wolgye-Dong, Nowon-Gu, Seoul 137-701 (Korea, Republic of); Ryu, Han-Yong; Lee, Jaimin [Agency for Defense Development, 462 Jochiwongil, Yuseong, Daejeon 305-605 (Korea, Republic of)

2010-11-15

451

Resolving the Unresolved Complex Mixtures of Hydrothermal Petroleum Using Comprehensive Two-Dimensional Gas Chromatography - Time of Flight Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Within hydrothermal systems sedimentary organic matter can be altered by high temperature fluids resulting in the generation of petroleum. These hydrothermal petroleums are compositionally similar to conventional, basin- formed petroleum, with the exception that they often contain substantial mixtures of coeluting organic compounds, which are difficult to resolve by traditional gas chromatographic methods. The coelution of these compounds produces a rapidly rising baseline in gas chromatogram that is referred to as an unresolved complex mixture (UCM). Little is known about these UCMs or why and how they form. In this study we analyzed the apolar fractions of four hydrothermal petroleum samples from the Middle Valley, Juan de Fuca Ridge and Escanaba Trough, Gorda Ridge in the NE Pacific Ocean and the Guaymus Basin, Gulf of California using comprehensive two-dimensional gas chromatography-Time of Flight Mass Spectrometry (GC×GC-ToFMS). The GC×GC-ToFMS chromatograms of these samples elucidate two hydrocarbon subsets. The first subset consists of commonly defined hydrocarbon series such as n-alkanes, alkylcyclohexanes, alkylbenzenes, naphthalenes, tricylic terpanes, steranes, and hopanes. The second subset is dominated by compounds forming the UCM. These compounds form a continuous series of configurational isomers that become increasingly aromatic at higher molecular weights. The UCMs of the hydrothermal petroleum samples vary as a function of the relative intensity, number, and molecular weight range of the contributing configurational isomers. The subset appears to represent areas of mass gain that overprint the first subset in the GC×GC-ToFMS chromatogram. This gain likely reflects an exogenous input or the accumulation of primary organic matter that underwent extensive dehydrogenation and dealkylation. Variation between the second hydrocarbon sample subsets is likely caused by different thermal gradients within the pyrolytic regimes, gaseous solubilization, hydrodynamic alteration from multi-component fluids, and post-depositional alteration from biodegradation and water-washing.

Ventura, G. T.; Reddy, C. M.; Simoneit, B. R.; Nelson, R. K.

2007-12-01

452

Material screening and selection for XENON100  

NASA Astrophysics Data System (ADS)

Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This dark matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples. Detailed tables with the radioactive contaminations of all screened samples are presented, together with the implications for XENON100.

Aprile, E.; Arisaka, K.; Arneodo, F.; Askin, A.; Baudis, L.; Behrens, A.; Bokeloh, K.; Brown, E.; Cardoso, J. M. R.; Choi, B.; Cline, D.; Fattori, S.; Ferella, A. D.; Giboni, K. L.; Kish, A.; Lam, C. W.; Lamblin, J.; Lang, R. F.; Lim, K. E.; Lopes, J. A. M.; Marrodán Undagoitia, T.; Mei, Y.; Melgarejo Fernandez, A. J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Plante, G.; Ribeiro, A. C. C.; Santorelli, R.; dos Santos, J. M. F.; Schumann, M.; Shagin, P.; Teymourian, A.; Thers, D.; Tziaferi, E.; Wang, H.; Weinheimer, C.; Laubenstein, M.; Nisi, S.

2011-09-01

453

Transportable Xenon Laboratory (TXL-1) Operations Manual  

SciTech Connect

The Transportable Xenon Laboratory Operations Manual is a guide to set up and shut down TXL, a fully contained laboratory made up of instruments to identify and measure concentrations of the radioactive isotopes of xenon by taking air samples and analyzing them. The TXL is housed in a standard-sized shipping container. TXL can be shipped to and function in any country in the world.

Thompson, Robert C.; Stewart, Timothy L.; Willett, Jesse A.; Woods, Vincent T.

2011-03-07

454

Solubility of cholesterol in supercritical ethane and binary gas mixtures containing ethane  

SciTech Connect

The solubility of cholesterol in supercritical ethane at 313.1, 323.1, and 333.1 K and 70--190 bar is presented as well as the solubility in ethane with 3.5 and 14 mol% propane and ethane with 3.5, 14, 50, and 96.5 mol% carbon dioxide at temperatures from 308.1 to 338.1 K and 85--220 bar. The results are compared with pr