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1

A Method for Calculating Viscosity and Thermal Conductivity of a Helium-Xenon Gas Mixture  

NASA Technical Reports Server (NTRS)

A method for calculating viscosity and thermal conductivity of a helium-xenon (He-Xe) gas mixture was employed, and results were compared to AiResearch (part of Honeywell) analytical data. The method of choice was that presented by Hirschfelder with Singh's third-order correction factor applied to thermal conductivity. Values for viscosity and thermal conductivity were calculated over a temperature range of 400 to 1200 K for He-Xe gas mixture molecular weights of 20.183, 39.94, and 83.8 kg/kmol. First-order values for both transport properties were in good agreement with AiResearch analytical data. Third-order-corrected thermal conductivity values were all greater than AiResearch data, but were considered to be a better approximation of thermal conductivity because higher-order effects of mass and temperature were taken into consideration. Viscosity, conductivity, and Prandtl number were then compared to experimental data presented by Taylor.

Johnson, Paul K.

2006-01-01

2

Energy disposal in the two-photon laser-assisted reaction in xenon and chlorine gas mixtures  

NASA Astrophysics Data System (ADS)

The two-photon laser assisted reaction (LAR) in low pressure xenon and chlorine gas mixtures has been studied over a broad range of excitation wavelengths in order to characterize the role of the entrance channel in determining the vibrational state distribution of the reaction products. We measure a high degree of vibrational excitation in the XeCl* product, confirming observations from previous studies of the LAR of Xe+Cl2 collision pairs [Ku et al., J. Phys. Chem. 87, 2989 (1983)], and in distinct contrast with the vibrationally cold excimer observed following laser excitation in molecular beam experiments [Boivineau et al., Chem. Phys. Lett. 128, 528 (1986)]. The mean vibrational energy in the XeCl excimer depends strongly on laser wavelength, increasing with decreasing wavelength. Moreover, an increasing fraction of the available energy from the reaction is observed as vibration in the XeCl* product as the laser is tuned toward shorter wavelengths. The reaction outcomes are interpreted in terms of a selectivity of initial conditions on the ionic potential surface that mediates the reactive collision.

Kohel, J.; Keto, J. W.

2000-12-01

3

Description and commissioning of NEXT-MM prototype: first results from operation in a Xenon-Trimethylamine gas mixture  

E-print Network

A technical description of NEXT-MM and its commissioning and first performance is reported. Having an active volume of ~35 cm drift $\\times$ 28 cm diameter, it constitutes the largest Micromegas-read TPC operated in Xenon ever constructed, made by a sectorial arrangement of the 4 largest single wafers manufactured with the Microbulk technique to date. It is equipped with a suitably pixelized readout and with a sufficiently large sensitive volume (~23 l) so as to contain long (~20 cm) electron tracks. First results obtained at 1 bar for Xenon and trimethylamine (Xe-(2 %)TMA) mixture are presented. The TPC can accurately reconstruct extended background tracks. An encouraging full-width half-maximum of 11.6 % was obtained for ~29 keV gammas without resorting to any data post-processing.

Álvarez, V; Borges, F I G M; Calvet, D; Cárcel, S; Castel, J; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Díaz, J; Druillole, F; Egorov, M; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Ferrer-Ribas, E; Freitas, E D C; Gehman, V M; Gil, A; Giomataris, I; Goldschmidt, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Coguie, A Le; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez, A; Martínez-Lema, G; Miller, T; Moiseenko, A; Mols, J P; Monrabal, F; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Palma, R; Pérez, J; Aparicio, J L Pérez; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, P; Santos, J M F dos; Segui, L; Serra, L; Shuman, D; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R C; White, J T; Yahlali, N

2013-01-01

4

Preliminary performance of a 4.97-inch radial turbine operating in a Brayton power system with a helium-xenon gas mixture  

NASA Technical Reports Server (NTRS)

The performance characteristics of the Brayton-rotating-unit's 4.97-inch radial turbine were investigated with the turbine part of a power conversion system. The following system parameters were varied: turbine inlet temperature from 1200 to 1600 F, compressor inlet temperature from 60 to 120 F, compressor outlet pressure from 20 to 45 psia, and shaft speed from 90-110 percent of rated speed (36000 rpm). The working fluid of the system was a gas mixture of helium-xenon with a nominal molecular weight of 83.8. Test results indicate that changes in system conditions have little effect on the turbine efficiency. At the design turbine inlet temperature of 1600 F and compressor inlet temperature of 80 F, an average turbine efficiency of 91 percent was obtained.

Leroy, M. J., Jr.; Ream, L. W.; Curreri, J. S.

1971-01-01

5

Scintillation luminescence for high-pressure xenon gas  

NASA Astrophysics Data System (ADS)

Scintillation and ionization yields in xenon gas for 5.49MeV alpha-particles were measured in the range of pressure from 0.35 to 3.7MPa and the electric field strength (E) over the number density of xenon atoms (N), E/N from 0 to 5×10-18Vcm2. When our data are normalized at the data point measured by Saito et al., the number of scintillation photons is 2.3×105 while the number of ionization electrons is 2.0×105 at 2.6MPa and at 3.7×10-18Vcm2. The scintillation and ionization yields of xenon doped with 0.2% hydrogen, High-Pressure Xenon gas[H2-0.2%], at 2.6MPa was also measured. Scintillation yield of the Xe-H2 mixture gas is 80% as high as that of pure xenon. It is found that the scintillation yield is luminous enough to generate a trigger pulse of the high-pressure xenon time projection chamber, which is expected as a promising MeV Compton gamma-ray camera.

Kobayashi, S.; Hasebe, N.; Igarashi, T.; Kobayashi, M.-N.; Miyachi, T.; Miyajima, M.; Okada, H.; Okudaira, O.; Tezuka, C.; Yokoyama, E.; Doke, T.; Shibamura, E.; Dmitrenko, V. V.; Ulin, S. E.; Vlasik, K. F.

2004-09-01

6

Gas mixtures for X-ray proportional counters  

NASA Technical Reports Server (NTRS)

Results are presented which detail the performance of proportional counters when filled with a wide variety of argon- and xenon-based gas mixtures. It is shown that alternative gas mixtures can offer considerable advantages in the counters. The mixtures of argon plus 10 percent propane and xenon plus 10 percent propylene look particularly attractive in terms of operating voltage and energy resolution. The quench gas CO2 returns the poorest results in all areas except aging.

Ramsey, B. D.; Agrawal, P. C.

1988-01-01

7

Xenon  

NASA Astrophysics Data System (ADS)

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 in dual (liquid/gas) phase, to detect simultaneously the ionization, through secondary scintillation in the gas, and primary scintillation in the liquid produced by low energy recoils. We review some of the results from the prototype XENON3 detector and briefly discuss about the status of current XENON10 at Gran Sasso Laboratory in Italy.

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

2007-11-01

8

RELAXATION PROCESSES OF Xe*(3P2) METASTABLE ATOMS IN ARGON-XENON MIXTURES  

E-print Network

L- 105 RELAXATION PROCESSES OF Xe*(3P2) METASTABLE ATOMS IN ARGON-XENON MIXTURES M. CHENEVIER, N*(3P2) by two-body collisions with argon k3, and by three-body collisions with an argon and a xenon Abstracts 34.50H - 82.20 Introduction. - Recently several types of xenon halide excimer laser have been

Paris-Sud XI, Université de

9

X-ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann (*) and C. Marti  

E-print Network

1527 X- ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann 1986) Résumé. 2014 En étudiant, par diffraction des rayons X, les mélanges xenon-krypton absorbés sur. Abstract 2014 Mixtures of xenon and krypton adsorbed on graphite at 45 K are studied by X ray diffraction

Boyer, Edmond

10

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

11

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

12

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

13

Penning gas mixtures for improving the energy resolution of proportional counters  

NASA Technical Reports Server (NTRS)

An experimental investigation of the Penning effect in both argon and xenon has been carried out with a variety of quench gases of different ionization potentials. Acetylene with argon and trimethylamine with xenon show the strongest true Penning effect, returning very high gas gains for a given voltage and improved energy resolution over more conventional mixtures. Data for these mixtures, as well as others exhibiting weaker metastable effects, nonmetastable Penning effects, and charge transfer through photoionization, are presented.

Agrawal, P. C.; Ramsey, B. D.

1989-01-01

14

Diffusion NMR methods applied to xenon gas for materials study  

NASA Technical Reports Server (NTRS)

We report initial NMR studies of (i) xenon gas diffusion in model heterogeneous porous media and (ii) continuous flow laser-polarized xenon gas. Both areas utilize the pulsed gradient spin-echo (PGSE) techniques in the gas phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients--a brief overview of this area is provided in the Introduction. The heterogeneous or multiple-length scale model porous media consisted of random packs of mixed glass beads of two different sizes. We focus on observing the approach of the time-dependent gas diffusion coefficient, D(t) (an indicator of mean squared displacement), to the long-time asymptote, with the aim of understanding the long-length scale structural information that may be derived from a heterogeneous porous system. We find that D(t) of imbibed xenon gas at short diffusion times is similar for the mixed bead pack and a pack of the smaller sized beads alone, hence reflecting the pore surface area to volume ratio of the smaller bead sample. The approach of D(t) to the long-time limit follows that of a pack of the larger sized beads alone, although the limiting D(t) for the mixed bead pack is lower, reflecting the lower porosity of the sample compared to that of a pack of mono-sized glass beads. The Pade approximation is used to interpolate D(t) data between the short- and long-time limits. Initial studies of continuous flow laser-polarized xenon gas demonstrate velocity-sensitive imaging of much higher flows than can generally be obtained with liquids (20-200 mm s-1). Gas velocity imaging is, however, found to be limited to a resolution of about 1 mm s-1 owing to the high diffusivity of gases compared with liquids. We also present the first gas-phase NMR scattering, or diffusive-diffraction, data, namely flow-enhanced structural features in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack. c2002 John Wiley & Sons, Ltd.

Mair, R. W.; Rosen, M. S.; Wang, R.; Cory, D. G.; Walsworth, R. L.

2002-01-01

15

Characteristic parameters of xenon near its liquid-gas critical point Yves Garrabos and Carole Lecoutre  

E-print Network

Characteristic parameters of xenon near its liquid-gas critical point Yves Garrabos and Carole the singular behaviors of the isothermal compressibility of xenon along the critical isochore in the homogeneous domain and the vapor-liquid coexisting densities of xenon in the nonhomogenous domain

Boyer, Edmond

16

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

17

Krypton assay in xenon at the ppq level using a gas chromatographic system and mass spectrometer  

NASA Astrophysics Data System (ADS)

We have developed a new method to measure krypton traces in xenon at unprecedented low concentrations. This is a mandatory task for many near-future low-background particle physics detectors. Our system separates krypton from xenon using cryogenic gas chromatography. The amount of krypton is then quantified using a mass spectrometer. We demonstrate that the system has achieved a detection limit of 8 ppq (parts per quadrillion) and present results of distilled xenon with krypton concentrations below 1 ppt.

Lindemann, Sebastian; Simgen, Hardy

2014-02-01

18

Characteristics of a high pressure gas proportional counter filled with xenon  

NASA Technical Reports Server (NTRS)

The characteristics of a conventional cylindrical geometry proportional counter filled with high pressure xenon gas up to 10 atm. were fundamentally investigated for use as a detector in hard X-ray astronomy. With a 2 percent methane gas mixture the energy resolutions at 10 atm. were 9.8 percent and 7.3 percent for 22 keV and 60 keV X-rays, respectively. From calculations of the Townsend ionization coefficient, it is shown that proportional counters at high pressure operate at weaker reduced electric field than low pressure counters. The characteristics of a parallel grid proportional counter at low pressure showed similar pressure dependence. It is suggested that this is the fundamental reason for the degradation of resolution observed with increasing pressure.

Sakurai, H.; Ramsey, B. D.

1991-01-01

19

Secondary avalanches in gas mixtures  

NASA Astrophysics Data System (ADS)

Avalanche development in gas-based detectors relies not only on direct ionisation but also on excitation of noble gas atoms. Some quencher molecules can be ionised when they collide with excited atoms, a process on which we reported earlier [1]. Alternatively, excited atoms can decay by photon emission. If these photons are insufficiently absorbed by the quencher, yet capable of ionising, then they may escape from the avalanche region and start secondary avalanches. This process, called photon feedback, leads to an over-exponential increase of the gas gain which limits the working range. In this paper, we derive photon feedback parameters from published gain measurements for several gas mixtures and fit these parameters in a model which describes their dependence on the quencher concentration and the pressure.

?ahin, Özkan; Tapan, ?lhan; Veenhof, Rob

2013-08-01

20

A technique for administering xenon gas anesthesia during surgical procedures in mice.  

PubMed

Carrying out invasive procedures in animals requires the administration of anesthesia. Xenon gas offers advantages as an anesthetic agent compared with other agents, such as its protection of the brain and heart from hypoxia-induced damage. The high cost of xenon gas has limited its use as an anesthetic in animal experiments, however. The authors designed and constructed simple boxes for the induction and maintenance of xenon gas and isoflurane anesthesia in small rodents in order to minimize the amount of xenon gas that is wasted. While using their anesthesia delivery system to anesthetize pregnant mice undergoing caesarean sections, they measured the respiratory rates of the anesthetized mice, the survival of the pups and the percentages of oxygen and carbon dioxide within the system to confirm the system's safety. PMID:25333593

Ruder, Arne Mathias; Schmidt, Michaela; Ludiro, Alessia; Riva, Marco A; Gass, Peter

2014-11-01

21

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

22

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

23

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

24

Tunable V.U.V. radiation generated by non-resonant phase matched odd harmonic generation in xenon gas  

E-print Network

in xenon gas Tran ba' Chu (1,*), A. Bouvier (1), A. J. Bouvier (1) and R. Fischer (2) (1) Laboratoire de.U.V. radiation has been generated by non-resonant fifth-harmonic generation in xenon in the domain 1135-1170 Ã?) of the xenon gas is of the order of 10-47 e.s.u. J. Phys. France 49 (1988) 1725-1729 OCTOBRE 1988

Boyer, Edmond

25

Cluster formation restricts dynamic nuclear polarization of xenon in solid mixtures  

PubMed Central

During dynamic nuclear polarization (DNP) at 1.5 K and 5 T, 129Xe nuclear magnetic resonance (NMR) spectra of a homogeneous xenon/1-propanol/trityl-radical solid mixture exhibit a single peak, broadened by 1H neighbors. A second peak appears upon annealing for several hours at 125 K. Its characteristic width and chemical shift indicate the presence of spontaneously formed pure Xe clusters. Microwave irradiation at the appropriate frequencies can bring both peaks to either positive or negative polarization. The peculiar time evolution of 129Xe polarization in pure Xe clusters during DNP can be modelled as an interplay of spin diffusion and T1 relaxation. Our simple spherical-cluster model offers a sensitive tool to evaluate major DNP parameters in situ, revealing a severe spin-diffusion bottleneck at the cluster boundaries and a significant sample overheating due to microwave irradiation. Subsequent DNP system modifications designed to reduce the overheating resulted in four-fold increase of 129Xe polarization, from 5.3% to 21%. PMID:22979875

Kuzma, N. N.; Pourfathi, M.; Kara, H.; Manasseh, P.; Ghosh, R. K.; Ardenkjaer-Larsen, J. H.; Kadlecek, S. J.; Rizi, R. R.

2012-01-01

26

PVT measurements for five natural gas mixtures  

E-print Network

Major Subject: Chemical Engineering PVT MEASUREMENTS FOR FIVE NATURAL GAS MIXTURES A Thesis by PHILIP PARAYIL SIMON Approved as to style and content by: James C. Holste (Chair of Committee) Kenneth N. Marsh (Member) Randolph C. Wilhoit (Member...) Raymond W. Flumerfelt (Head of Department) August 1991 ABSTRACT PVT Measurements for Five Natural Gas Mixtures (August 1991) Philip Parayil Simon, B. Tech. , Indian Institute of Technology, Madras Chair of Advisory Committee: Dr. James C. Holste...

Simon, Philip Parayil

1991-01-01

27

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

28

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

29

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

30

Physiological response of rats to delivery of helium and xenon: implications for hyperpolarized noble gas imaging  

NASA Technical Reports Server (NTRS)

The physiological effects of various hyperpolarized helium and xenon MRI-compatible breathing protocols were investigated in 17 Sprague-Dawley rats, by continuous monitoring of blood oxygen saturation, heart rate, EKG, temperature and endotracheal pressure. The protocols included alternating breaths of pure noble gas and oxygen, continuous breaths of pure noble gas, breath-holds of pure noble gas for varying durations, and helium breath-holds preceded by two helium rinses. Alternate-breath protocols up to 128 breaths caused a decrease in oxygen saturation level of less than 5% for either helium or xenon, whereas 16 continuous-breaths caused a 31.5% +/- 2.3% decrease in oxygen saturation for helium and a 30.7% +/- 1. 3% decrease for xenon. Breath-hold protocols up to 25 s did not cause the oxygen saturation to fall below 90% for either of the noble gases. Oxygen saturation values below 90% are considered pathological. At 30 s of breath-hold, the blood oxygen saturation dropped precipitously to 82% +/- 0.6% for helium, and to 76.5% +/- 7. 4% for xenon. Breath-holds longer than 10 s preceded by pre-rinses caused oxygen saturation to drop below 90%. These findings demonstrate the need for standardized noble gas inhalation procedures that have been carefully tested, and for continuous physiological monitoring to ensure the safety of the subject. We find short breath-hold and alternate-breath protocols to be safe procedures for use in hyperpolarized noble gas MRI experiments. Copyright 2000 John Wiley & Sons, Ltd.

Ramirez, M. P.; Sigaloff, K. C.; Kubatina, L. V.; Donahue, M. A.; Venkatesh, A. K.; Albert, M. S.; ALbert, M. S. (Principal Investigator)

2000-01-01

31

Diffusion in mercury-argon gas mixtures  

NASA Astrophysics Data System (ADS)

Ab initio quantum-mechanical calculations of potential of interactions U( R) are performed for Hg-Ar. Using equations from the molecular kinetic theory of rarefied gases, a new statistical correlation is found between data on the potential of interaction (molecular beams, molecular spectroscopy, and potential U( R)) and experimental data on the mutual diffusion coefficient (MDC) of mercury-argon gas mixtures. Calculated reference data on the MDC of mercury-argon gas mixtures in the temperature range of 300 to 600 K are offered as a possible standard for calibrating instruments that measure MDCs of liquid vapors and inert gases using the Stefan method.

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

2014-04-01

32

Xenon-nitrogen chemistry: gas-phase generation and theoretical investigation of the xenon-difluoronitrenium ion F2N-Xe+.  

PubMed

The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (?H and ?G) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions. PMID:21826753

Operti, Lorenza; Rabezzana, Roberto; Turco, Francesca; Borocci, Stefano; Giordani, Maria; Grandinetti, Felice

2011-09-12

33

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

34

Removal of COâ from gas mixtures  

Microsoft Academic Search

An improved, catalyzed process for the removal of COâ from gas mixtures is described using a solution containing 15-40% by weight of potassium carbonate in which the absorption efficiency is enhanced by the addition of sodium or potassium vanadate equivalent to 2 to 10% by weight of VâOâ and sodium or potassium borate equivalent to 1 to 10% by weight

Eickmeyer

1984-01-01

35

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas  

SciTech Connect

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

36

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

37

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

38

An improved measurement of electron-ion recombination in high-pressure xenon gas  

E-print Network

We report on results obtained with the NEXT-DEMO prototype of the NEXT-100 high-pressure xenon gas time projection chamber (TPC), exposed to an alpha decay calibration source. Compared to our previous measurements with alpha particles, an upgraded detector and improved analysis techniques have been used. We measure event-by-event correlated fluctuations between ionization and scintillation due to electron-ion recombination in the gas, with correlation coeffcients between -0.80 and -0.56 depending on the drift field conditions. By combining the two signals, we obtain a 2.8 % FWHM energy resolution for 5.49 MeV alpha particles and a measurement of the optical gain of the electroluminescent TPC. The improved energy resolution also allows us to measure the specific activity of the radon in the gas due to natural impurities. Finally, we measure the average ratio of excited to ionized atoms produced in the xenon gas by alpha particles to be $0.561\\pm 0.045$, translating into an average energy to produce a primary scintillation photon of $W_{\\rm ex}=(39.2\\pm 3.2)$ eV.

NEXT Collaboration; L. Serra; M. Sorel; V. Álvarez; F. I. G. Borges; M. Camargo; S. Cárcel; S. Cebrián; A. Cervera; C. A. N. Conde; T. Dafni; J. Díaz; R. Esteve; L. M. P. Fernandes; P. Ferrario; A. L. Ferreira; E. D. C. Freitas; V. M. Gehman; A. Goldschmidt; J. J. Gómez-Cadenas; D. González-Díaz; R. M. Gutiérrez; J. Hauptman; J. A. Hernando Morata; D. C. Herrera; I. G. Irastorza; L. Labarga; A. Laing; I. Liubarsky; N. Lopez-March; D. Lorca; M. Losada; G. Luzón; A. Marí; J. Martín-Albo; G. Martínez-Lema; A. Martínez; T. Miller; F. Monrabal; M. Monserrate; C. M. B. Monteiro; F. J. Mora; L. M. Moutinho; J. Muñoz Vidal; M. Nebot-Guinot; D. Nygren; C. A. B. Oliveira; J. Pérez; J. L. Pérez Aparicio; M. Querol; J. Renner; L. Ripoll; A. Rodríguez; J. Rodríguez; F. P. Santos; J. M. F. dos Santos; D. Shuman; A. Simón; C. Sofka; J. F. Toledo; J. Torrent; Z. Tsamalaidze; J. F. C. A. Veloso; J. A. Villar; R. Webb; J. T. White; N. Yahlali

2014-12-11

39

A novel 83mKr tracer method for characterizing xenon gas and cryogenic distillation systems  

NASA Astrophysics Data System (ADS)

The radioactive isomer 83mKr, has many properties that make it very useful for various applications. Its low energy decay products, like conversion, shake-off and Auger electrons as well as X- and ?-rays are used for calibration purposes in neutrino mass experiments and direct dark matter detection experiments. Thanks to the short half-life of 1.83 h and the decay to the ground state 83Kr, one does not risk contamination of any low-background experiment with long-lived radionuclides. In this paper, we present a new approach, using 83mKr as a radioactive tracer in noble gases. A method of doping 83mKr, into xenon gas and its detection, using special custom-made detectors, based on a photomultiplier tube, is described. Two applications of this method are presented: firstly, it can be used to characterize the particle flow inside of gas routing systems and determine the circulation speed of gas particles inside of a gas purification system for xenon. Secondly, it is used for rapid estimating of the separation performance of a distillation system.

Rosendahl, S.; Bokeloh, K.; Brown, E.; Cristescu, I.; Fieguth, A.; Huhmann, C.; Lebeda, O.; Levy, C.; Murra, M.; Schneider, S.; V'enos, D.; Weinheimer, C.

2014-10-01

40

An improved measurement of electron-ion recombination in high-pressure xenon gas  

E-print Network

We report on results obtained with the NEXT-DEMO prototype of the NEXT-100 high-pressure xenon gas time projection chamber (TPC), exposed to an alpha decay calibration source. Compared to our previous measurements with alpha particles, an upgraded detector and improved analysis techniques have been used. We measure event-by-event correlated fluctuations between ionization and scintillation due to electron-ion recombination in the gas, with correlation coeffcients between -0.80 and -0.56 depending on the drift field conditions. By combining the two signals, we obtain a 2.8 % FWHM energy resolution for 5.49 MeV alpha particles and a measurement of the optical gain of the electroluminescent TPC. The improved energy resolution also allows us to measure the specific activity of the radon in the gas due to natural impurities. Finally, we measure the average ratio of excited to ionized atoms produced in the xenon gas by alpha particles to be $0.561\\pm 0.045$, translating into an average energy to produce a primary s...

Serra, L; Álvarez, V; Borges, F I G; Camargo, M; Cárcel, S; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Díaz, J; Esteve, R; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gehman, V M; Goldschmidt, A; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Irastorza, I G; Labarga, L; Laing, A; Liubarsky, I; Lopez-March, N; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez-Lema, G; Martínez, A; Miller, T; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Pérez, J; Aparicio, J L Pérez; Querol, M; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Shuman, D; Simón, A; Sofka, C; Toledo, J F; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R; White, J T; Yahlali, N

2014-01-01

41

Wire Counters with a New Gas Mixture  

Microsoft Academic Search

A multiwire chamber using a gas mixture of argon, isobutane and ¿-trichlorethane-1, 1, 1 (CH3.CCl3) has been successfully operated. Although this chamber does not operate in the proportional mode (i.e., pulse height is not a linear function of the primary ionization) we feel it has a substantial advantage over conventional proportional chambers especially when it is used to detect high

M. Atac

1972-01-01

42

Shear viscosity of hadronic gas mixtures  

E-print Network

We investigate the effects of baryon chemical potential \\mu on the shear viscosity coefficient \\eta and the viscosity to entropy density ratio \\eta/s of a pion-nucleon gas mixture. We find that \\eta is an increasing function of T and \\mu, while the ratio \\eta/s turns to a decreasing function in a wide region of T-\\mu plane. In the kinematical region we studied, the smallest value of \\eta/s is about 0.3.

K. Itakura; O. Morimatsu; H. Otomo

2008-05-12

43

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

44

IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES  

SciTech Connect

This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

Jason M. Keith

2005-02-01

45

Dusty Plasma Structures in Gas Mixtures  

SciTech Connect

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

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

2008-09-07

46

HDT mixtures treatment strategies by gas chromatography  

SciTech Connect

Gas phase chromatographic processes are of interest for the separation of hydrogen isotopes from an HDT mixture. For a certain quantity, they are very competitive and present several benefits. Nevertheless no active packing material allows to have simultaneously good enrichment performances for tritium production and high decontamination capabilities for HD gases. The influence of the packing material is first described in this article. Then two specific processes (TCAP and Reverse Chromatography), each well adapted to perform one target, are presented. Finally, the problematic to propose an optimized treatment scheme associating these two processes is formulated. (authors)

Laquerbe, C.; Contreras, S.; Demoment, J. [Commissariat a l'Energie Atomique - CEA/Valduc, F-21121 Is sur Tille (France)

2008-07-15

47

Inhalation pressure distributions for medical gas mixtures calculated in an infant airway morphology model.  

PubMed

A numerical pressure loss model previously used for adult human airways has been modified to simulate the inhalation pressure distribution in a healthy 9-month-old infant lung morphology model. Pressure distributions are calculated for air as well as helium and xenon mixtures with oxygen to investigate the effects of gas density and viscosity variations for this age group. The results indicate that there are significant pressure losses in infant extrathoracic airways due to inertial effects leading to much higher pressures to drive nominal flows in the infant airway model than for an adult airway model. For example, the pressure drop through the nasopharynx model of the infant is much greater than that for the nasopharynx model of the adult; that is, for the adult-versus-child the pressure differences are 0.08 cm H2O versus 0.4 cm H2O, 0.16 cm H2O versus 1.9 cm H2O and 0.4 cm H2O versus 7.7 cm H2O, breathing helium-oxygen (78/22%), nitrogen-oxygen (78/22%) and xenon-oxygen (60/40%), respectively. Within the healthy lung, viscous losses are of the same order for the three gas mixtures, so the differences in pressure distribution are relatively small. PMID:24697250

Gouinaud, Laure; Katz, Ira; Martin, Andrew; Hazebroucq, Jean; Texereau, Joëlle; Caillibotte, Georges

2015-09-01

48

NEXT, high-pressure xenon gas experiments for ultimate sensitivity to Majorana neutrinos  

E-print Network

In this paper we describe an innovative type of Time Projection Chamber (TPC), which uses high-pressure xenon gas (HPXe) and electroluminescence amplification of the ionization charge as the basis of an apparatus capable of fully reconstructing the energy and topological signature of rare events. We will discuss a specific design of such HPXe TPC, the NEXT-100 detector, that will search for neutrinoless double beta decay events using 100-150 kg of xenon enriched in the isotope Xe-136. NEXT-100 is currently under construction, after completion of an accelerated and very successful R&D period. It will be installed at the Laboratorio Subterr\\'aneo de Canfranc (LSC), in Spain. The commissioning run is expected for late 2013 or early 2014. We will also present physics arguments that suggest that the HPXe technology can be extrapolated to the next-to-next generation (e.g, a fiducial mass of 1 ton of target), which will fully explore the Majorana nature of the neutrino if the mass hierarchy is inverse.

J. J. Gómez-Cadenas; J. Martín-Albo; F. Monrabal; for the NEXT Collaboration

2012-11-21

49

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

PubMed

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

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

2002-04-01

50

Development of Imaging High Pressure Xenon Gas Scintillation Drift Chambers for Use in Gamma Ray Burst Astronomy  

Microsoft Academic Search

This thesis describes the development of the Scintillation Imaging Gas-filled Hard X-ray Telescope (SIGHT), a balloon -borne instrument designed to make astronomical observations in the 35-300 keV energy range. The telescope utilizes a high pressure xenon gas scintillation drift chamber (GSDC) as the X-ray detector sitting behind a coded aperture mask. The GSDC offers ~2% FWHM energy resolution over the

Jeffrey Alan Wilkerson

1995-01-01

51

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

52

Is xenon eldest?  

NASA Technical Reports Server (NTRS)

It is well known that the solubility of noble gases in magmas decreases with increasing atomic weight. Xenon, the weightiest of the stable noble gases, is the least soluble atmospheric gas in magma. It is not unreasonable to suppose that the noble gases should have degassed from (or equilibrated with) a bubbling mantle in order of increasing solubility, such that xenon was the most rapidly degassed and helium the least. The apparent relative ages of the famous radiogenic noble gas isotopes agrees, at least qualitatively, with this premise. When atmospheric loss processes are assigned their proper place, several long-standing xenonological puzzles become added evidence for xenon's relative antiquity. Xenon being the afore-mentioned sense the oldest atmospheric gas, will have been most greatly subject to escape, be it impact-driven or EUV-driven. Nonradiogenic xenon's pronounced isotopic fractionation has already been attributed to escape; why it should be more fractionated than krypton would be assigned to xenon's greater atmospheric age. The small atmospheric inventory of xenon relative to the other nonradiogenic noblegases, known as the 'missing xenon' problem, could easily be explained by differential escape. The relatively tiny atmospheric inventories of the radiogenic daughter products of 129 Iodine and 244 Plutonium, both much smaller than would be expected from the inferred abundances of the parents in meteorites, offer a third and fourth data to support the hypothesis that Earth has lost most of its xenon.

Zahnle, K.

1994-01-01

53

Transport Properties of operational gas mixtures used at LHC  

E-print Network

This report summarizes some useful data on the transport characteristics of gas mixtures which are required for detection of charged particles in gas detectors. We try to replace Freon used for RPC detector in the CMS experiment with another gas while maintaining the good properties of the Freon gas mixture unchanged. We try to switch to freonless gas mixture because Freon is not a green gas, it is very expensive and its availability is decreasing. Noble gases like Ar, He, Ne and Xe (with some quenchers like carbon dioxide, methane, ethane and isobutene) are investigated. Transport parameters like drift velocity, diffusion, Townsend coefficient, attachment coefficient and Lorentz angle are computed using Garfield software for different gas mixtures and compared with experimental data.

Yasser Assran; Archana Sharma

2011-10-31

54

Electrical Breakdown in a Martian Gas Mixture  

NASA Technical Reports Server (NTRS)

The high probability for dust interactions during Martian dust storms and dust devils combined with the cold, dry climate of Mars most likely result in airborne dust that is highly charged. On Earth, potential gradients up to 5 kV/m have been recorded and in some cases resulted in lightning. Although the Martian atmosphere is not conducive to lightning generation, it is widely believed that electrical discharge in the form of a corona occurs. In order to understand the breakdown of gases, Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes. The minimum potential is plotted versus the pressure-distance value for electrodes of a given geometry. For most gases, the potential decreases as the pressure decreases. For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries. However, a very small amount (<0.1%) of mixing gases radically changes the curve, as noted by Leach. Here, we present the first experimental results of a Paschen curve for a Mars gas mixture compared with 100% pure CO2.

Buhler, C. R.; Calle, C. I.; Nelson, E.

2003-01-01

55

Development of a Custom CRDS-based Trace Gas Analyzer for Argon and Xenon  

NASA Astrophysics Data System (ADS)

Noble liquid-based dark matter detectors are sensitive to parts-per-billion (ppb) concentrations of impurities of O2, N2, and H2O, which reduce the scintillation light yield and disrupt the ionization signal. In order to achieve an optimal light yield and collection of the ionization signal, DARKSIDE is designing a cryogenic distillation unit to achieve large quantities of depleted argon with a purity at sub-ppb levels. Critical to the success of the depleted argon dark matter detector will be the development of a system capable of analyzing these impurities at the sub-ppb level. A trace gas analyzer based on cw-Cavity Ring-Down Spectroscopy (CRDS) technology is being built at Black Hills State University that exceeds the current limits of commercially available systems. CRDS involves measuring the decay rate of the intensity of monochromatic light transmitted at the mirrors enclosing a cavity filled with a sample of gas. By comparing the decay rates for light at a resonance frequency of the contaminant of interest with that of light slightly off-resonance, a direct measurement of the amount of absorbing material (the contaminant) is obtained. Designed to measure ultra-low levels of elemental impurities, the BHSU system will be critical to such experiments as DARKSIDE and other dark matter searches based on liquid argon and xenon.

Keeter, K. J.; Durben, D.; Zehfus, M.; Galbiati, C.; Mei, D.; Sun, Y.; Alton, A.

2010-03-01

56

Low-energy ion emission from a xenon gas-puff laser-plasma X-ray source  

NASA Astrophysics Data System (ADS)

We have measured low-energy ion emission from a gas-puff laser-plasma X-ray source. The ions may cause the degradation of the condenser mirror of the extreme ultra-violet projection lithography system. A 0.7 J in 8 ns Nd:YAG laser at 1.06 ?m was focused onto the xenon gas-puff target with an intensity of 1012 W/cm2. The silicon (111) plates, placed at a distance of 32 mm from the laser-interaction region, were exposed with the xenon ions. The average ion energy was measured to be less than 50 eV with a Faraday-cup detector placed close to the silicon plates. The xenon deposition occurred in the silicon plates with a depth of less than 40 nm. The deposition density was measured with a quadrupole secondary ion mass spectrometer to be 1021 /cm3 after 1500 laser shots. The energy-conversion efficiency from the laser energy into the ions is 0.1%/4 ?sr/shot. For the lithography system, if we can remove such ion bombardment completely using novel techniques such as electro-magnetic devices or gas flow curtain techniques, the lifetime of the condenser mirror will be extended significantly.

Daido, H.; Yamagami, S.; Suzuki, M.; Azuma, H.; Choi, I. W.; Fiedorowicz, H.

57

New approach in direct-simulation of gas mixtures  

NASA Technical Reports Server (NTRS)

Results are reported for an investigation of a new direct-simulation Monte Carlo method by which energy transfer and chemical reactions are calculated. The new method, which reduces to the variable cross-section hard sphere model as a special case, allows different viscosity-temperature exponents for each species in a gas mixture when combined with a modified Larsen-Borgnakke phenomenological model. This removes the most serious limitation of the usefulness of the model for engineering simulations. The necessary kinetic theory for the application of the new method to mixtures of monatomic or polyatomic gases is presented, including gas mixtures involving chemical reactions. Calculations are made for the relaxation of a diatomic gas mixture, a plane shock wave in a gas mixture, and a chemically reacting gas flow along the stagnation streamline in front of a hypersonic vehicle. Calculated results show that the introduction of different molecular interactions for each species in a gas mixture produces significant differences in comparison with a common molecular interaction for all species in the mixture. This effect should not be neglected for accurate DSMC simulations in an engineering context.

Chung, Chan-Hong; De Witt, Kenneth J.; Jeng, Duen-Ren

1991-01-01

58

Barium Ion Extraction and Identification from Laser Induced Fluorescence in Gas for the Enriched Xenon Observatory  

NASA Astrophysics Data System (ADS)

The scientific community is increasingly interested in neutrinoless double beta decay. A potential measurement of the decay rate would determine the neutrino mass and would be sensitive to some extensions of the Standard Model of particle physics. Unfortunately, the decay rate is very low and competes with natural and cosmogenic radioactivity. This thesis presents a technique that eliminates such background events. It is performed by observing the barium ion daughter from the double beta decay of xenon-136 using laser induced fluorescence. The technique is very complex and requires an excellent understanding of the barium ion spectroscopy and its chemistry in the vicinity of other molecules. Such a technique will become a unique advantage over other neutrinoless double beta decay experiments, especially if the neutrino mass is low. This thesis describes three main topics. The first one describes simulations of ionizing electrons in xenon to determine the size of a gas phase detector for a neutrinoless double beta decay measurement. It has been determined that a meter size detector would contain most electron tracks. Then, it describes the design of two barium ion sources, one relying on electric discharges across two electrodes and the other one using a high energy pulsed laser. From those sources, the spectroscopy of barium ions was studied. The branching ratio of the 62S1/2 -- ---6 2P1/2 transition was found to be 74 +/- 4%. By adding argon in the chamber, the lineshift of the transition due to collisions was found to be -132 MHz/torr while the broadening rate was 23 MHz/torr. Finally, the most interesting topic is the production of doubly charged barium ions using an electrospray source. From it, ions were extracted to vacuum in a mass spectrometer and charge conversion was achieved using triethylamine. The efficiency of the conversion of Ba+ to Ba ++ was almost 100%, with a cross-section between 1.69 x 10 -18 m2 and 2.21 x 10-18 m 2 without forming any molecules.

Rollin, Etienne

59

Optimal detectors for WIMP and 0–? ?? searches: Identical high-pressure xenon gas TPCs?  

Microsoft Academic Search

A time projection chamber (TPC) filled with high-pressure gaseous xenon (HPXe)—instead of liquid xenon (LXe)—appears likely to offer both superior energy resolution for the 0–? ?? decay search in 136Xe and superior ?-background rejection in the search for WIMPs. An augmentation to maximize the primary scintillation detection efficiency of the 0–? ?? decay detector design will realize an optimum design

David Nygren

2007-01-01

60

Optimal detectors for WIMP and 0 nu betabeta searches: Identical high-pressure xenon gas TPCs?  

Microsoft Academic Search

A time projection chamber (TPC) filled with high-pressure gaseous xenon (HPXe)---instead of liquid xenon (LXe)---appears likely to offer both superior energy resolution for the 0 nu betabeta decay search in 136Xe and superior gamma-background rejection in the search for WIMPs. An augmentation to maximize the primary scintillation detection efficiency of the 0 nu betabeta decay detector design will realize an

David Nygren

2007-01-01

61

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

62

Composition for absorbing hydrogen from gas mixtures  

DOEpatents

A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

Heung, Leung K. (Aiken, SC); Wicks, George G. (Aiken, SC); Lee, Myung W. (Aiken, SC)

1999-01-01

63

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

64

A novel $^{83\\mathrm{m}}$Kr tracer method for characterizing xenon gas and cryogenic distillation systems  

E-print Network

The radioactive isomer $^{83\\mathrm{m}}$Kr has many properties that make it very useful for various applications. Its low energy decay products, like conversion, shake-off and Auger electrons as well as X- and $\\gamma$-rays are used for calibration purposes in neutrino mass experiments and direct dark matter detection experiments. Thanks to the short half-life of 1.83 h and the decay to the ground state $^{83}$Kr, one does not risk contamination of any low-background experiment with long- lived radionuclides. In this paper, we present two new applications of $^{83\\mathrm{m}}$Kr. It can be used as a radioactive tracer in noble gases to characterize the particle flow inside of gas routing systems. A method of doping $^{83\\mathrm{m}}$Kr into xenon gas and its detection, using special custom-made detectors, based on a photomultiplier tube, is described. This technique has been used to determine the circulation speed of gas particles inside of a gas purification system for xenon. Furthermore, 83m Kr can be used to...

Rosendahl, S; Brown, E; Cristescu, I; Fieguth, A; Huhmann, C; Lebeda, O; Levy, C; Murra, M; Schneider, S; Vénos, D; Weinheimer, C

2014-01-01

65

Reduced viscosity interpreted for fluid/gas mixtures  

NASA Technical Reports Server (NTRS)

Analysis predicts decrease in fluid viscosity by comparing pressure profile of fluid/gas mixture with that of power-law fluid. Fluid is taken to be viscous, non-Newtonian, and incompressible; the gas to be ideal; the flow to be inertia-free, isothermal, and one dimensional. Analysis assists in design of flow systems for petroleum, coal, polymers, and other materials.

Lewis, D. H.

1981-01-01

66

Free wave propagation in binary gas mixtures  

Microsoft Academic Search

The problem concerning the propagation of free waves in binary mixtures of monatomic ideal gases is analyzed by using a kinetic model of the Boltzmann equation which is compatible with the two-fluid hydrodynamic theory. Comparison of the theoretical results with available experimental data shows that the two-fluid model equation can be used to describe the wave-vector dependence of the free

A. S. Fernandes; W. Marques Jr

2005-01-01

67

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The sample cell at the heart of CVX-2 will sit inside a thermostat providing three layers of insulation. The cell itself comprises a copper body that conducts heat efficiently and smoothes out thermal variations that that would destroy the xenon's uniformity. Inside the cell, the oscillating screen viscometer element is supported between two pairs of electrodes that deflect the screen and then measure screen motion.

2001-01-01

68

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

2001-01-01

69

High severity pyrolysis of shale and petroleum gas oil mixtures  

Microsoft Academic Search

Light gas oil and heavy gas oil from Paraho shale oil and their mixtures with a petroleum light gas oil were pyrolyzed in the presence of steam at 880-900°C and contact times between 60 and 90 ms in a nonisothermal bench-scale pyrolysis reactor. Blending of petroleum LGO into the shale oil feeds provided product yields that were the weighted linear

Harry P. Leftin; David S. Newsome

1986-01-01

70

New RPC gas mixtures for large area apparatuses  

NASA Astrophysics Data System (ADS)

The working gas choise has always been a crucial topic for RPC. The optimization of the gas mixture, for different purposes, allowed the RPC detector to be successful in many experiments of today physics [1,2]. Both running and future experiments however could profit from new gases with low environmental impact, low cost and good behavior with respect to ageing and RPC performances. We present here the first results in the search for this new gas.

Cardarelli, R.; Di Stante, L.; Liberti, B.; Paolozzi, L.; Pastori, E.; Santonico, R.

2014-11-01

71

Antiapoptotic activity of argon and xenon  

PubMed Central

Although chemically non-reactive, inert noble gases may influence multiple physiological and pathological processes via hitherto uncharacterized physical effects. Here we report a cell-based detection system for assessing the effects of pre-defined gas mixtures on the induction of apoptotic cell death. In this setting, the conventional atmosphere for cell culture was substituted with gas combinations, including the same amount of oxygen (20%) and carbon dioxide (5%) but 75% helium, neon, argon, krypton, or xenon instead of nitrogen. The replacement of nitrogen with noble gases per se had no effects on the viability of cultured human osteosarcoma cells in vitro. Conversely, argon and xenon (but not helium, neon, and krypton) significantly limited cell loss induced by the broad-spectrum tyrosine kinase inhibitor staurosporine, the DNA-damaging agent mitoxantrone and several mitochondrial toxins. Such cytoprotective effects were coupled to the maintenance of mitochondrial integrity, as demonstrated by means of a mitochondrial transmembrane potential-sensitive dye and by assessing the release of cytochrome c into the cytosol. In line with this notion, argon and xenon inhibited the apoptotic activation of caspase-3, as determined by immunofluorescence microscopy coupled to automated image analysis. The antiapoptotic activity of argon and xenon may explain their clinically relevant cytoprotective effects. PMID:23907115

Spaggiari, Sabrina; Kepp, Oliver; Rello-Varona, Santiago; Chaba, Kariman; Adjemian, Sandy; Pype, Jan; Galluzzi, Lorenzo; Lemaire, Marc; Kroemer, Guido

2013-01-01

72

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

2001-01-01

73

The thermomagnetic torque in nitrogen helium gas mixtures  

E-print Network

TNT. The non-spherical spherical particle interaction was studied by varying the helium concentration in the mixture and measuring the change in the charac- teristic maximum magnetic field-pressure ratio, (-H) and the p max maximum torque t mes... ABSTRACT The Thermomagnetic Torque in Nitrogen Helium Gas Mixtures. (August 1977) Walter Balamy Aschenbeck, Jr. , B. S. , Texas A&N University Chairman of Advisory Committee: Dr. T. W. Adair, III The thermomagnetic torque (TNT) was measured in nitrogen...

Aschenbeck, Walter Balamy

1977-01-01

74

Gas sampling system for reactive gas-solid mixtures  

DOEpatents

An apparatus and method for sampling a gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extend in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

Daum, Edward D. (Alliance, OH); Downs, William (Alliance, OH); Jankura, Bryan J. (Mogadore, OH); McCoury, Jr., John M. (Mineral City, OH)

1989-01-01

75

Gas sampling system for reactive gas-solid mixtures  

DOEpatents

An apparatus and method for sampling gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extends in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

Daum, Edward D. (Alliance, OH); Downs, William (Alliance, OH); Jankura, Bryan J. (Mogadore, OH); McCoury, Jr., John M. (Mineral City, OH)

1990-01-01

76

Methods for certifying test gas mixtures  

Microsoft Academic Search

The most common colorimetric method of determining small concentrations of oxygen (from 0.001 to 1% by volume) is based on the conversion of monovalent copper ions into bivalent ions by oxidation with the oxygen contained in the analyzed gas. Bivalent copper ions form with ammonia a blue-colored compound. The intensity of coloring thus obtained is compared with the coloring of

É. M. Malkova; T. L. Radovskaya; M. P. Belozerova; Z. T. Berestneva

1963-01-01

77

In situ measurements of Krypton in Xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

E-print Network

A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of $330 \\pm 200$ ppt.

Ethan Brown; Stephan Rosendahl; Christian Huhmann; Christian Weinheimer; Hans Kettling

2012-12-20

78

In situ measurements of krypton in xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

NASA Astrophysics Data System (ADS)

A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of 330±200 ppt.

Brown, E.; Rosendahl, S.; Huhmann, C.; Weinheimer, C.; Kettling, H.

2013-02-01

79

The XENON Dark Matter Experiment  

E-print Network

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 a fiducial mass of 1000 kg of liquid xenon, a sufficiently low threshold of ~16 keV recoil energy and an un-rejected background rate of 10 events per year, XENON would be sensitive to a WIMP-nucleon interaction cross section of 10^(-46) cm^2, for WIMPs with masses above 50 GeV. The 1 tonne scale experiment (XENON1T) will be realized with an array of ten identical 100 kg detector modules (XENON100). The detectors are time projection chambers operated in dual (liquid/gas) phase, to detect simultaneously the ionization, through secondary scintillation in the gas, and primary scintillation in the liquid produced by low energy recoils. The distinct ratio of primary to secondary scintillation for nuclear recoils from WIMPs (or neutrons), and for electron recoils from background, is key to the event-by-event discrimination capability of XENON. A 3kg dual phase detector with light readout provided by an array of 7 photomultipliers is currently being tested, along with other prototypes dedicated to various measurements relevant to the XENON program. We present some of the results obtained to-date and briefly discuss the next step in the phased approach to the XENON experiment, i.e. the development and underground deployment of a 10 kg detector (XENON10) within 2005.

XENON Collaboration; Elena Aprile

2005-02-15

80

Novel sorbent development and evaluation for the capture of krypton and xenon from nuclear fuel reprocessing off-gas stream  

SciTech Connect

The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, Idaho National Laboratory sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up. (authors)

Garn, T.G.; Greenhalgh, M.R.; Law, J.D. [Idaho National Laboratory, 1625 N. Fremont Ave., Idaho Falls, ID 83415 (United States)

2013-07-01

81

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of liquid xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Resembling a tiny bit of window screen, the oscillator at the heart of CVX-2 will vibrate between two pairs of paddle-like electrodes. The slight bend in the shape of the mesh has no effect on the data. What counts are the mesh's displacement in the xenon fluid and the rate at which the displacement dampens. The unit shown here is encased in a small test cell and capped with a sapphire windown to contain the xenon at high pressure.

2001-01-01

82

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

83

The XENON100 Dark Matter Experiment  

NASA Astrophysics Data System (ADS)

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

2009-04-01

84

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

85

Single ion trapping in a buffer gas and liquid xenon energy resolution studies for the EXO experiment  

NASA Astrophysics Data System (ADS)

Recent neutrino oscillation results provide experimental proof that neutrinos are massive particles. These measurements, however, reveal information about neutrino mass differences, as opposed to the absolute mass values themselves. Observation of a rare nuclear transition called neutrinoless double beta decay (0nubetabeta) would constitute an absolute neutrino mass measurement. This decay requires that neutrinos are massive Majorana particles, and that lepton number conservation is violated. Observation of this decay will undoubtedly reveal physics beyond the current Standard Model of particle physics. Current limits on the half-life of 0nubetabeta are > 1025 yr, providing a formidable experimental challenge. The Enriched Xenon Observatory (EXO) is a double beta decay experiment poised to improve upon this limit, using 136Xe as both a source and detector of this decay. 0nubetabeta of 136Xe produces a detectable energy deposition, in addition to a single 136Ba ++ decay daughter which can be used to tag this rare process. This thesis deals with the details of energy deposition in liquid xenon, as well as the first observation of single Ba ions in a high pressure buffer-gas filled RF Paul trap.

Wodin, Jesse

86

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

87

Calibration and uncertainty assessment for certified reference gas mixtures.  

PubMed

The weighted least squares method to build an analysis function described in ISO 6143, Gas analysis--Comparison methods for determining and checking the composition of calibration gas mixtures, is modified to take into account the typically small number of instrumental readings that are obtained for each primary standard gas mixture used in calibration. The theoretical basis for this modification is explained, and its superior performance is illustrated in a simulation study built around a concrete example, using real data. The corresponding uncertainty assessment is obtained by application of a Monte Carlo method consistent with the guidance in the Supplement 1 to the Guide to the expression of uncertainty in measurement, which avoids the need for two successive applications of the linearizing approximation of the conventional method for uncertainty propagation. The three main steps that NIST currently uses to certify a reference gas mixture (homogeneity study, calibration, and assignment of value and uncertainty assessment), are described and illustrated using data pertaining to an actual standard reference material. PMID:21072506

Guenther, Franklin R; Possolo, Antonio

2011-01-01

88

30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Exemption of small low pressure gas cylinders containing nonflammable...1106-6 Exemption of small low pressure gas cylinders containing nonflammable...nonexplosive gas mixtures. Small low pressure gas cylinders containing...

2010-07-01

89

30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.  

...2014-07-01 false Exemption of small low pressure gas cylinders containing nonflammable...75.1106-6 Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. Small low pressure gas cylinders containing...

2014-07-01

90

Artificial neural networks and gas sensor arrays: quantification of individual components in a gas mixture  

Microsoft Academic Search

A very promising way of increasing the selectivity and sensitivity of gas sensors is to treat the signals from a number of different gas sensors with pattern recognition (PARC) methods. A gas sensor array with six metal-oxide-semiconductor field-effect-transistors (MOSFETs) operating at elevated temperatures was exposed to two types of multiple-component gas mixture, one containing 5-65 ppm of hydrogen, ammonia, ethanol

H. Sundgren; F. Winquist; I. Lukkari; I. Lundstrom

1991-01-01

91

Optimal detectors for WIMP and 0 ? ?? searches: Identical high-pressure xenon gas TPCs?  

NASA Astrophysics Data System (ADS)

A time projection chamber (TPC) filled with high-pressure gaseous xenon (HPXe)—instead of liquid xenon (LXe)—appears likely to offer both superior energy resolution for the 0-? ?? decay search in 136Xe and superior ?-background rejection in the search for WIMPs. An augmentation to maximize the primary scintillation detection efficiency of the 0-? ?? decay detector design will realize an optimum design for both purposes. In this scenario an attractive synergy exists: two identical HPXe TPCs differing only in isotopic content will provide significantly more robust evidence for the existence of either signal if present. A simple analysis of important factors that limit energy resolution leads to the conclusion that the optimal design for either next-generation search at the few hundred kg level is the same HPXe-based TPC. A careful measurement of the scintillation and ionization responses of HPXe to nuclear and electronic recoils is needed to test the claim of HPXe superiority to LXe for the combined goals.

Nygren, David

2007-11-01

92

Plasma polymerization of an ethylene-nitrogen gas mixture  

NASA Technical Reports Server (NTRS)

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

Hudis, M.; Wydeven, T.

1975-01-01

93

Gas Mixtures and Ozone Production in an Electrical Discharge  

Microsoft Academic Search

The quantitative production of ozone (O3) with N2, O2, and Ar gas mixtures in an atmospheric pressure corona discharge (CD) is investigated. A five-part model is presented that explores the discharge conditions needed for optimum ozone production. One part of the model is the well-known relationship that correlates the discharge's voltage, frequency, gap, dielectric material, etc with the generator's yield.

Thomas J. Manning; Jerry Hedden

2001-01-01

94

Predicting detection probabilities for gas mixtures over HSI backgrounds  

SciTech Connect

Detecting and identifying weak gaseous plumes using thermal image data acquired by airborne detectors is an area of ongoing research. This contribution investigates the relative detectability of gas mixtures over different backgrounds and a range of plume temperatures that are warmer and cooler than the ground. The focus of this analysis to support mission planning. When the mission is intended to collect evidence of particular chemicals, the analysis presented is this report can be used to determine conditions under which useful data can be acquired. Initial analyses can be used to determine whether LWIR is useful for the anticipated gas, temperature, and background combination.

Tardiff, Mark F.; Walsh, Stephen J.; Anderson, Kevin K.; Chilton, Lawrence

2009-12-29

95

Nuclear reactor excitation of XeF laser gas mixtures  

NASA Astrophysics Data System (ADS)

Kinetic studies of the XeF laser system and other laser media have been studied under low-power (several kW/cu cm), long-pulse (100-200 microsec) pumping conditions using fission-fragment pumping. Results include the measurement of fluorescence from excited states of KrF, N2(+), and XeF and optical gain near 351 nm in gas mixtures containing Xe, NF3, and a rare gas. Sandia's fast-pulse reactor facility (SPR III) was used for these experiments, in which a cell containing the gas mixtures is irradiated with thermalized neutrons. Energy deposition in the gas occurs through the interaction of energetic charged particles produced by neutron-induced fission events. Two pumping modes have been examined. One mode uses He-3 as the rare gas, where charged particles from the He-3 (n,p) H-3 reaction excite the medium. Another mode uses fission fragments from U-235, which is coated on thin ceramic substrates, as the source of excitation.

Rice, James K.; Hays, Gerald N.; Neal, Daniel R.; McArthur, David A.; Alford, William J.

96

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

Code of Federal Regulations, 2011 CFR

...fuel mixtures containing natural gas or petroleum. 503.38 Section 503.38 Energy...fuel mixtures containing natural gas or petroleum. (a) Eligibility. Section...proposes to use a mixture of natural gas or petroleum and an alternate fuel as a primary...

2011-01-01

97

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

Code of Federal Regulations, 2012 CFR

...fuel mixtures containing natural gas or petroleum. 503.38 Section 503.38 Energy...fuel mixtures containing natural gas or petroleum. (a) Eligibility. Section...proposes to use a mixture of natural gas or petroleum and an alternate fuel as a primary...

2012-01-01

98

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

...fuel mixtures containing natural gas or petroleum. 503.38 Section 503.38 Energy...fuel mixtures containing natural gas or petroleum. (a) Eligibility. Section...proposes to use a mixture of natural gas or petroleum and an alternate fuel as a primary...

2014-01-01

99

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

Code of Federal Regulations, 2010 CFR

...fuel mixtures containing natural gas or petroleum. 503.38 Section 503.38 Energy...fuel mixtures containing natural gas or petroleum. (a) Eligibility. Section...proposes to use a mixture of natural gas or petroleum and an alternate fuel as a primary...

2010-01-01

100

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

Code of Federal Regulations, 2013 CFR

...fuel mixtures containing natural gas or petroleum. 503.38 Section 503.38 Energy...fuel mixtures containing natural gas or petroleum. (a) Eligibility. Section...proposes to use a mixture of natural gas or petroleum and an alternate fuel as a primary...

2013-01-01

101

Modeling of non-thermal plasma in flammable gas mixtures  

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

102

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air  

NASA Astrophysics Data System (ADS)

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

2014-07-01

103

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air  

SciTech Connect

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308?nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Gulati, P., E-mail: pgulati1512@gmail.com [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India); Prakash, R.; Pal, U. N.; Kumar, M. [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Vyas, V. [Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India)

2014-07-07

104

Understanding the response behavior of potentiometric gas sensors for non-equilibrium gas mixtures  

SciTech Connect

Many applications of gas sensors require concentration measurements of reactive gases in mixtures that are out of thermodynamic equilibrium. These applications include: hydrogen and hydrocarbon fuel gas sensors operating in ambient air for explosion hazard detection, carbon monoxide detection in ambient air for health protection, combustion efficiency sensors for stoichiometry control, and nitric oxide sensors for air pollution monitoring. Many potentiometric and amperometric electrochemical sensor technologies have been developed for these applications. A class of the potentiometric sensors developed for gas mixtures are the non-Nerstian sensors. This presentation defines a categorization and theoretical analysis of three distinct electrochemical processes that can produce a non-Nernstian sensor response.

Garzon, F. H. (Fernando H.); Mukundan, R. (Rangachary); Brosha, E. L. (Eric L.)

2002-01-01

105

A Decade of Xenon Chemistry  

ERIC Educational Resources Information Center

Presents reactions for the formation of xenon compounds and compounds of the other inert gases. Provides bonding and structure theories for noble gas compounds and speculates on possible applications. (GS)

Moody, G. J.

1974-01-01

106

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2001 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure that is placed inside a pressure canister. A similar canister holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD. This is a detail view of MSFC 0100143.

2001-01-01

107

High-Calorific Gas Mixtures Produced from Biomass  

NASA Astrophysics Data System (ADS)

Investigations in the field of processing of different types of biomass into high calorific gas fuel are carried out in the Joint Institute for High Temperatures of RAS. Design of technology for effective processing of low-grade solid fuel to gas mixtures which can be used as fuel for power plants is rather actual problem both in the view of natural resources conservation and in the view of the development of autonomous energy unit for thermal and electric power supply. The experimental data on quantity and composition of the gaseous products formed in the process of peat pyrolysis are presented at various operating parameters of the process. It is shown that as a result of peat pyrolysis and the subsequent cracking of emanating products at temperature 1,000 °C it is possible to receive 1.4 m3 of gas with specific caloricity 11.7 MJ/m3 per 1 kg of original raw material.

Kosov, Valentin; Kosov, Vladimir; Sinelschikov, Vladimir; Zaichenko, Victor

108

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

109

Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media  

NASA Technical Reports Server (NTRS)

We have extended the utility of NMR as a technique to probe porous media structure over length scales of approximately 100-2000 microm by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t), of the xenon gas filling the pore space to study further the measurements of both the pore surface-area-to-volume ratio, S/V(p), and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of approximately 0.62-0.65D(0), that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D(0) at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D(0) was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D(0) and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D(0) from the S/V(p) relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) points lay above the interpolation line in the case of small beads, due to diffusion during the gradient pulse on the order of the pore size, it was also noted that the experimental D(t) data fell below the Pade line in the case of large beads, most likely due to finite size effects.

Mair, R. W.; Hurlimann, M. D.; Sen, P. N.; Schwartz, L. M.; Patz, S.; Walsworth, R. L.

2001-01-01

110

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

111

Preparation of neutron-activated xenon for liquid xenon detector calibration  

Microsoft Academic Search

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a 5-day activation of natural xenon gas with a 252Cf (4×105n\\/s) source, the activities of two gamma ray lines

K. Ni; R. Hasty; T. M. Wongjirad; L. Kastens; A. Manzur; D. N. McKinsey

2007-01-01

112

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

113

Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry  

PubMed Central

Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance. PMID:25325339

Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

2014-01-01

114

Critical Viscosity of Xenon investigators  

NASA Technical Reports Server (NTRS)

Dr. Dr. Robert F. Berg (right), principal investigator and Dr. Micheal R. Moldover (left), co-investigator, for the Critical Viscosity of Xenon (CVX/CVX-2) experiment. They are with the National Institutes of Standards and Technology, Gaithersburg, MD. The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of chemicals.

2001-01-01

115

Two fluid gas and dust mixtures in SPH  

NASA Astrophysics Data System (ADS)

One of the most challenging aspects of numerical simula3ons of dust and gas mixtures is the o6en enormous difference between gas and dust evolu3onary 3me scales. Whenever the dust stopping 3me becomes much smaller than the gas evolu3onary 3me scale, explicit/ implicit integra3on schemes require an excessively large number of 3me-steps, and none of the previous SPH schemes in the two fluid approach (Monaghan & Kocharyan 1995 and 1997; Maddison, Humble & Murray 2003; Rice et al. 2004; Barriere-Fouchet et al. 2005, Laibe & Price 2012) have addressed this problem. In the present work, a method to avoid the 3me integra3on of the small dusty grains evolu3on equa3ons, in the Smoothed Par3cle Hydrodynamics (SPH) two fluid approach is proposed. By assuming a very simple exponen3al decay model for the rela3ve velocity between the gas and dust components, all the effec3ve characteris3cs of the drag force can be reproduced. Taking as a reference the recent work of Laibe & Price (2011/12) a series of tests have been performed in order to compare the accuracy of the present method with a standard integra3on method.

Loren-Aguilar, Pablo; Bate, Matthew R.

2013-07-01

116

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

117

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

Code of Federal Regulations, 2010 CFR

...SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging...a mixture of compressed gas and other material. ...the liquefied compressed gas at 131 °F. plus any...Mixtures containing compressed gas or gases including...

2010-10-01

118

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

...Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying...Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying...powerplants, OFP may prohibit the use of petroleum or natural gas in such...

2014-01-01

119

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

Code of Federal Regulations, 2012 CFR

...Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying...Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying...powerplants, OFP may prohibit the use of petroleum or natural gas in such...

2012-01-01

120

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

Code of Federal Regulations, 2013 CFR

...Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying...Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying...powerplants, OFP may prohibit the use of petroleum or natural gas in such...

2013-01-01

121

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

Code of Federal Regulations, 2011 CFR

...Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying...Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying...powerplants, OFP may prohibit the use of petroleum or natural gas in such...

2011-01-01

122

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

Code of Federal Regulations, 2010 CFR

...Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying...Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying...powerplants, OFP may prohibit the use of petroleum or natural gas in such...

2010-01-01

123

The XENON1T Demonstrator  

NASA Astrophysics Data System (ADS)

We present the results from a facility called the XENON1T Demonstrator at Columbia University, that has been designed and built as a prototype for the XENON1T cryogenic system and TPC. Its primary goal is to demonstrate that the high LXe purity (<1 part per billion O2 equivalent) required for electrons to drift freely over a distance of 1 meter, as in the XENON1T TPC, can be achieved and on a time scale of weeks. The approach adopted in all XENON detectors thus far is that of gas purification with continuous circulation with a diaphragm pump through a heated getter. We show results for high speed recirculation, above 100 slpm, the development of a high voltage feedthrough which is radio pure and the design and application of a prototype TPC to test the purity.

Budnik, Ran; Aprile, Elena; Choi, Bin; Contreras, Hugo; Goetzke, Luke; Lim, Kyungeun; Lang, Rafael; Melgarejo, Antonio; Persiani, Rino; Plante, Guillaume; Rizzo, Alfio; Shagin, Peter

2012-03-01

124

The Search for Dark Matter with the XENON100 Experiment  

NASA Astrophysics Data System (ADS)

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

2008-11-01

125

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

126

Application of Two Phase (Liquid/Gas) Xenon Gamma-Camera for the Detection of Special Nuclear Material and PET Medical Imaging  

SciTech Connect

The McKinsey group at Yale has been awarded a grant from DTRA for the building of a Liquid Xenon Gamma Ray Color Camera (LXe-GRCC), which combines state-of-the-art detection of LXe scintillation light and time projection chamber (TPC) charge readout. The DTRA application requires a movable detector and hence only a single phase (liquid) xenon detector can be considered in this case. We propose to extend the DTRA project to applications that allow a two phase (liquid/gas) xenon TPC. This entails additional (yet minimal) hardware and extension of the research effort funded by DTRA. The two phase detector will have better energy and angular resolution. Such detectors will be useful for PET medical imaging and detection of special nuclear material in stationary applications (e.g. port of entry). The expertise of the UConn group in gas phase TPCs will enhance the capabilities of the Yale group and the synergy between the two groups will be very beneficial for this research project as well as the education and research projects of the two universities. The LXe technology to be used in this project has matured rapidly over the past few years, developed for use in detectors for nuclear physics and astrophysics. This technology may now be applied in a straightforward way to the imaging of gamma rays. According to detailed Monte Carlo simulations recently performed at Yale University, energy resolution of 1% and angular resolution of 3 degrees may be obtained for 1.0 MeV gamma rays, using existing technology. With further research and development, energy resolution of 0.5% and angular resolution of 1.3 degrees will be possible at 1.0 MeV. Because liquid xenon is a high density, high Z material, it is highly efficient for scattering and capturing gamma rays. In addition, this technology scales elegantly to large detector areas, with several square meter apertures possible. The Yale research group is highly experienced in the development and use of noble liquid detectors for astrophysics, most recently in the XENON10 experiment. The existing facilities at Yale are fully adequate for the completion of this project. The facilities of the UConn group at the LNS at Avery Point include a (clean) lab for detector development and this group recently delivered an Optical Readout TPC (O-TPC) for research in Nuclear Astrophysics at the TUNL in Duke University. The machine shop at UConn will be used (free of charge) for producing the extra hardware needed for this project including grids and frames.

McKinsey, Daniel Nicholas [Yale University] [Yale University

2013-08-27

127

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

128

Proportional chambers for very high counting rates based on gas mixtures of CF4 with hydrocarbons  

Microsoft Academic Search

Very fast multiwire proportional chambers of low mass for very high counting rates were developed. The anode signals have an effective duration of 8 ns after pulse shaping and a time jitter of only 4 ns fwhm. This performance was achieved with gas mixtures of CF4 and hydrocarbons at atmospheric pressure in MWPCs with small interelectrode distances. Gas mixtures with

J. Fischer; A. Hrisoho; V. Radeka; P. Rehak

1985-01-01

129

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

130

Gas-liquid nucleation of nonideal binary mixtures. I. A density functional study  

Microsoft Academic Search

The binary gas–liquid nucleation of model Lennard-Jones mixtures is studied using density functional methods. It is shown that the ordinary ‘‘Ar’’–‘‘Kr’’ mixture shows stronger nonclassical nucleation behavior than previously thought. A more nonideal mixture is defined by modifying the usual mixing rules of the Lennard-Jones parameters. This fluid exhibits significantly stronger surface activity than the ordinary mixture. As with water\\/alcohol

Ari Laaksonen; David W. Oxtoby

1995-01-01

131

Measuring electron lifetime and V0 in Liquid Xenon  

NASA Astrophysics Data System (ADS)

We present performances and results of the Purity Monitoring system developed at Gran Sasso National Laboratories for the XENON experiment. We tested two versions of this device in Liquid Xenon (LXe): one in dedicated chamber, cryostat and gas system, and a smaller one in the XENON3 prototype.

Ferella, A. D.

2007-03-01

132

Metastable sound speed in gas-liquid mixtures  

NASA Technical Reports Server (NTRS)

A new method of calculating speed of sound for two-phase flow is presented. The new equation assumes no phase change during the propagation of an acoustic disturbance and assumes that only the total entropy of the mixture remains constant during the process. The new equation predicts single-phase values for the speed of sound in the limit of all gas or all liquid and agrees with available two-phase, air-water sound speed data. Other expressions used in the two-phase flow literature for calculating two-phase, metastable sound speed are reviewed and discussed. Comparisons are made between the new expression and several of the previous expressions -- most notably a triply isentropic equation as used, a triply isentropic equation as used, among others, by Karplus and by Wallis. Appropriate differences are pointed out and a thermodynamic criterion is derived which must be satisfied in order for the triply isentropic expression to be thermodynamically consistent. This criterion is not satisfied for the cases examined, which included two-phase nitrogen, air-water, two-phase parahydrogen, and steam-water. Consequently, the new equation derived is found to be superior to the other equations reviewed.

Bursik, J. W.; Hall, R. M.

1979-01-01

133

Response of tomato plants to simulated landfill gas mixtures  

SciTech Connect

The roots of tomato plants were fumigated with simulated refuse-generated gas mixtures at levels of methane (CH/sub 4/), carbon dioxide (CO/sub 2/), and oxygen (O/sub 2/) previously measured in the atmospheres of landfill cover soils associated with poor growth or death of plants. A concentration of 18% CO/sub 2/ or greater, exceeded in almost 30% of thirty-two landfills examined throughout the US, caused reduced growth and visible symptoms on tomato after 1 wk, regardless of O/sub 2/ level. Doubling the CO/sub 2/ level to that encountered in a typical local site (Edgeboro Landfill) resulted in more severe symptom development and the subsequent death of plants. Methane, in concentrations of 20% and above, found in more than 25% of the landfills visited, while not observed to be toxic per se; was associated with drastic O/sub 2/ depletion in the soil atmosphere, which activity was believed to be the cause of the plant decline.

Arthur, J.J.; Leone, I.A.; Flower, F.B.

1985-01-01

134

Verification of a logarithmic model for estimation of gas concentrations in a mixture for a tin oxide gas sensor response  

Microsoft Academic Search

Changes in electrical conductivity due to a reaction occurring between the original adsorbents and the gases present in the surrounding atmosphere were measured for a tin dioxide-based gas sensor. In this study, a model of the gas sensor response using a relationship between the gas concentration in a mixture and the sensor resistance is proposed. The values of coefficients are

Shigeki Hirobayashi; Mohammed Afrose Kadir; Toshio Yoshizawa; Tatsuo Yamabuchi

2003-01-01

135

Magnetic resonance imaging of convection in laser-polarized xenon R. W. Mair,1  

E-print Network

Magnetic resonance imaging of convection in laser-polarized xenon R. W. Mair,1 C.-H. Tseng,1,2 G. P and diffusion of laser-polarized xenon (129 Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid

Walsworth, Ronald L.

136

Influence of Xenon on Protein Hydration as measured by a Microwave Absorption Technique  

Microsoft Academic Search

INVESTIGATIONS into the transport mechanisms of xenon during xenon anæsthesia1,2 showed that this noble gas associates reversibly with the blood proteins3. Standard (PVT) uptake measurements showed that for human hæmoglobin in aqueous solution (at 20° C; 1 atm. xenon pressure pH 7) 1.8 moles of xenon associate per mole of hæmoglobin4.

B. P. Schoenborn; R. M. Featherstone

1964-01-01

137

Two-dimensional simulation of the development of an inhomogeneous volume discharge in a Ne/Xe/HCl gas mixture  

SciTech Connect

The kinetic processes accompanying plasma column formation in an inhomogeneous discharge in a Ne/Xe/HCl gas mixture at a pressure of 4 atm were investigated by using a two-dimensional model. Two cathode spots spaced by 0.7 cm were initiated by distorting the cathode surface at local points, which resulted in an increase in the field strength in the cathode region. Three regimes differing in the charging voltage, electric circuit inductance, and electric field strength at the local cathode points were considered. The spatiotemporal distributions of the discharge current; the electron density; and the densities of excited xenon atoms, HCl(v = 0) molecules in the ground state, and HCl(v > 0) molecules in vibrational levels were calculated. The development of the discharge with increasing the electron density from 10{sup 4} to 10{sup 16} cm{sup -3} was analyzed, and three characteristic stages in the evolution of the current distribution were demonstrated. The width of the plasma column was found to depend on the energy deposited in the discharge. The width of the plasma column was found to decrease in inverse proportion to the deposited energy due to spatiotemporal variations in the rates of electron production and loss. The calculated dependences of the cross-sectional area of the plasma column on the energy deposited in the discharge agree with the experimental results.

Bychkov, Yu. I., E-mail: bych-yu@yandex.ru; Yampolskaya, S. A.; Yastremskii, A. G. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation)

2013-05-15

138

Separation of gas mixtures by transition-metal complexes  

Microsoft Academic Search

The selective separation or purification of gases, especially hydrogen and CO, is highly desirable in processes utilizing product gas from coal gasification. However, gas separation is a difficult and energy intensive process. The development of new and innovative methodologies to selectively and efficiently separate specific gas components from mixed-gas streams would significantly reduce the cost and complexity of product gas

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

1988-01-01

139

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

140

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

Code of Federal Regulations, 2011 CFR

... Prohibition against excessive use of petroleum or natural gas in mixtures-electing... Prohibition against excessive use of petroleum or natural gas in mixtures—electing...feasible for a unit to use a mixture of petroleum or natural gas and an alternate...

2011-01-01

141

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

Code of Federal Regulations, 2013 CFR

... Prohibition against excessive use of petroleum or natural gas in mixtures-electing... Prohibition against excessive use of petroleum or natural gas in mixtures—electing...feasible for a unit to use a mixture of petroleum or natural gas and an alternate...

2013-01-01

142

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

Code of Federal Regulations, 2012 CFR

... Prohibition against excessive use of petroleum or natural gas in mixtures-electing... Prohibition against excessive use of petroleum or natural gas in mixtures—electing...feasible for a unit to use a mixture of petroleum or natural gas and an alternate...

2012-01-01

143

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

... Prohibition against excessive use of petroleum or natural gas in mixtures-electing... Prohibition against excessive use of petroleum or natural gas in mixtures—electing...feasible for a unit to use a mixture of petroleum or natural gas and an alternate...

2014-01-01

144

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

Code of Federal Regulations, 2010 CFR

... Prohibition against excessive use of petroleum or natural gas in mixtures-electing... Prohibition against excessive use of petroleum or natural gas in mixtures—electing...feasible for a unit to use a mixture of petroleum or natural gas and an alternate...

2010-01-01

145

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography. The Vaporization Enthalpy of  

E-print Network

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography of correlation-gas chromatography to measure the vaporization enthalpy {l g Hm(298.15 K)} of complex mixtures obtained for the mixture. Correlation-gas chromatography is applicable in obtaining the vaporization

Chickos, James S.

146

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

Microsoft Academic Search

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

Larry G. Mastin; Mark S. Ghiorso

2001-01-01

147

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography. The  

E-print Network

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography April 21, 2005. Revised Manuscript Received June 2, 2005 The use of correlation-gas chromatography using gas chromatography. Some variance in composition with the literature values has been observed

Chickos, James S.

148

Liquid xenon excimer laser  

SciTech Connect

The characteristics of the first excimer laser and the history of its creation are presented. The threshold lasing conditions and the modern theory of active media are considered, and the prospects for the development of excimer lasers operating on condensed inert gases are discussed. It is shown that in experiments on pumping liquid xenon, lasing was obtained simultaneously on excimers of several types, including excimers in liquid and gas phases. (special issue devoted to the 80th anniversary of academician n g basov's birth)

Molchanov, Alexander G [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2003-01-31

149

Rayleigh-Brillouin Light Scattering from Noble Gas Mixtures. 2. Partial Structure Factors  

Microsoft Academic Search

We derive a relation between the static structure factor for a mixture and experimental quantities that can be extracted from a Rayleigh-Brillouin light scattering experiment: the Landau-Placzek ratio and Brillouin shift. Partial structure factors are related to the thermodynamic quantities that characterize a mixture in a similar way as the Kirkwood-Buff integrals. In a He + Xe noble gas mixture,

Arjen Bot; G. H. Wegdam

1991-01-01

150

Critical Viscosity of Xenon team  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

2001-01-01

151

Critical Viscosity of Xenon team  

NASA Technical Reports Server (NTRS)

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD.

2001-01-01

152

Process for recovery of ammonia from an ammonia-containing gas mixture  

Microsoft Academic Search

This patent describes a process for separating ammonia from a gaseous mixture thereof with other gaseous components. It comprises: contacting the gaseous mixture with one side of a gas separation composite membrane comprising a porous support coated with a thin-layer of a cation exchange type polymer containing the sulfonic acid ion exchange group in a polymer molecule.

B. Bikson; J. K. Nelson; J. E. Perrin

1991-01-01

153

Transient flow in pipelines of high-pressure hydrogen–natural gas mixtures  

Microsoft Academic Search

The purpose of this study is the numerical modeling of high-pressure transient flow of hydrogen–natural gas mixtures in rigid pipelines. The governing equations for such flows are two coupled, non-linear, hyperbolic, partial differential equations. The fluid pressure and velocity are considered as two principal dependent variables. The fluid is a homogeneous hydrogen–natural gas mixture for which the density is defined

Sami Elaoud; Ezzeddine Hadj-Taïeb

2008-01-01

154

Gas gain limitation in low pressure proportional counters filled with TEG mixtures  

NASA Astrophysics Data System (ADS)

Proportional counters filled with tissue equivalent gas mixtures (TEPC) can be used to simulate interactions and energy transferred to small tissue volumes. One criteria which allows to use TEPC as the dose meter is that the particle ranges are larger compared to the gas volume. TEPC achieve this by operating at low gas pressures. Single ionization events dominate the distribution of low-LET radiation at low gas pressure and therefore their detection is of primary importance, a high gas gain is necessary. Therefore gas gain factor has been measured for Methane- and Propane-based tissue equivalent gas mixtures. The highest stable gas gains, second ionization Townsend coefficient and electron avalanche dimensions have been determined.

Kowalski, T. Z.

2014-12-01

155

Measurements of laminar burning velocities for natural gas-hydrogen-air mixtures  

SciTech Connect

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 (f from 0.6 to 1.4). The influence of stretch rate on flame was also analyzed. The results show that, for lean mixture combustion, the flame radius increases with time but the increasing rate decreases with flame expansion for natural gas and for mixtures with low hydrogen fractions, while at high hydrogen fractions, there exists a linear correlation between flame radius and time. For rich mixture combustion, the flame radius shows a slowly increasing rate at early stages of flame propagation and a quickly increasing rate at late stages of flame propagation for natural gas and for mixtures with low hydrogen fractions, and there also exists a linear correlation between flame radius and time for mixtures with high hydrogen fractions. Combustion at stoichiometric mixture demonstrates the linear relationship between flame radius and time for natural gas-air, hydrogen-air, and natural gas-hydrogen-air flames. Laminar burning velocities increase exponentially with the increase of hydrogen fraction in mixtures, while the Markstein length decreases and flame instability increases with the increase of hydrogen fractions in mixture. For a fixed hydrogen fraction, the Markstein number shows an increase and flame stability increases with the increase of equivalence ratios. Based on the experimental data, a formula for calculating the laminar burning velocities of natural gas-hydrogen-air flames is proposed. (author)

Huang, Zuohua; Zhang, Yong; Zeng, Ke; Liu, Bing; Wang, Qian; Jiang, Deming [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an (People's Republic of China)

2006-07-15

156

Xenon and Other Volatile Anesthetics Change Domain Structure in Model Lipid Raft Membranes  

PubMed Central

Inhalation anesthetics have been in clinical use for over 160 years, but the molecular mechanisms of action continue to be investigated. Direct interactions with ion channels received much attention after it was found that anesthetics do not change the structure of homogeneous model membranes. However, it was recently found that halothane, a prototypical anesthetic, changes domain structure of a binary lipid membrane. The noble gas xenon is an excellent anesthetic and provides a pivotal test of the generality of this finding, extended to ternary lipid raft mixtures. We report that xenon and conventional anesthetics change the domain equilibrium in two canonical ternary lipid raft mixtures. These findings demonstrate a membrane-mediated mechanism whereby inhalation anesthetics can affect the lipid environment of trans-membrane proteins. PMID:24299622

Weinrich, Michael; Worcester, David L.

2014-01-01

157

Theoretical prediction of stable noble-gas anions XeNO(2)(-) and XeNO(3)(-) with very short xenon-nitrogen bond lengths.  

PubMed

We have predicted a new type of noble-gas anions, XeNO(2)(-) and XeNO(3)(-) with very short Xe-N bond lengths ( approximately 1.8 A), using high-level electronic structure theory with extended atomic basis sets. The chemical bonding between xenon and nitrogen atoms could formally be assigned as triple bonds. The best estimates of the atomization energies of the two anions were found to be 50 and 101 kcal/mol, respectively, and the lowest unimolecular dissociation barriers were estimated to be approximately 42 kcal/mol. These anions were predicted to be kinetically stable at low temperature. The possible neutral "salts" formed between the lithium cation and these two anions were also discussed. PMID:20695437

Sun, Yi-Lun; Hong, Jie-Ting; Hu, Wei-Ping

2010-09-01

158

Adsorption of 85 Kr radioactive inert gas into hardening mixtures  

Microsoft Academic Search

Changes in volumetric activity of 85Kr radioactive inert gas take place in the atmosphere: it has increased by around 50% during the past 15 years. The main source\\u000a of such gas is the operation of nuclear power plants and spent nuclear fuel reprocessing plants. 85Kr as an inert gas spreads throughout the entire atmosphere and its ionizing radiation may result in

D. Butkus; J. Kleiza

2011-01-01

159

Hyperpolarized Xenon for NMR and MRI Applications  

PubMed Central

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2. Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode. PMID:22986346

Witte, Christopher; Kunth, Martin; Döpfert, Jörg; Rossella, Federica; Schröder, Leif

2012-01-01

160

Exploring interaction effects in two-component gas mixtures using orthogonal signal correction of ultrasound pulses  

NASA Astrophysics Data System (ADS)

Within Sweden and the EU, an increased use of biogas gas and natural gas is encouraged to decrease emission of carbon dioxide. To support more effective manufacturing, distribution, and consumption of energy gases, new methods for the measurement of the calorimetric value or the gas composition are needed. This paper presents a method to extract and visualize variations in ultrasound pulse shape, caused by interaction effects between the constituents of a two-component gas mixture. The method is based on a combination of principal component analysis and orthogonal signal correction. Pulse-echo ultrasound experiments on mixtures of oxygen and ethane in the concentration range from 20% to 80% ethane show that the extracted information could be correlated with the molar fraction of ethane in the mixture. .

Carlson, Johan E.; Martinsson, Pär-Erik

2005-05-01

161

Proportional chambers for very high counting rates based on gas mixtures of CF 4 with hydrocarbons  

NASA Astrophysics Data System (ADS)

Very fast multiwire proportional chambers of low mass for very high counting rates were developed. The anode signals have an effective duration of 8 ns after pulse shaping and a time jitter of only 4 ns fwhm. This performance was achieved with gas mixtures of CF 4 and hydrocarbons at atmospheric pressure in MWPCs with small interelectrode distances. Gas mixtures with high primary specific ionization density and low noise fast signal processing provide full efficiency at gas gains of a few times 10 4. At these conditions, the chambers can operate at rates of several times 10 7 s -1 cm -2. Various gas mixtures and chamber geometries were explored and test results are reported.

Fischer, J.; Hrisoho, A.; Radeka, V.; Rehak, P.

1985-08-01

162

Consistent Boundary Conditions for Multicomponent Real Gas Mixtures Based on Characteristic Waves  

NASA Astrophysics Data System (ADS)

Previously developed characteristic-wave-based boundary conditions for multicomponent perfect gas mixtures are here extended to real gas mixtures. The characteristic boundary conditions are derived from the one-dimensional wave decomposition of the Euler equations, and the wave amplitude variations are determined from the prescribed boundary conditions on the flow variables. The viscous conditions are applied separately. For multidimensional simulations, the boundary conditions for each coordinate direction are applied additively. These boundary conditions are tested on a representative two-dimensional problem-the propagation of an incompressible vortex by a supersonic flow with outflow conditions specified as nonreflecting-solved using a high-order finite-difference scheme. Simulations conducted for a heptane-nitrogen mixture flow with strong real gas effects display excellent, nonreflective wave behavior as the vortex leaves the computational domain, verifying the suitability of this method for the multidimensional multicomponent real gas flows computed.

Okong'o, Nora; Bellan, Josette

2002-03-01

163

Nanostructure synthesis from high velocity gas mixture flows  

NASA Astrophysics Data System (ADS)

The synthesis of nanostructures is an emerging field of science, modern physics and technologies. The gas dynamic methods have become the instrument of fundamental researches and new basis of vacuum technologies. The gas jet deposition has taken important place in surface modification: deposition of metal, semiconductor, polymer films. History of rarefied gas dynamics and space sciences gave birth to fundamental knowledge for the progress in vacuum nanoscience and nanotechnology. Diamond synthesis holds a special place using the chemical vapor deposition method, based on processes in low density gases. The science on nanostructure synthesis now is on the boundary of new breakthroughs.

Rebrov, Aleksey K.

2014-12-01

164

Laser Cooling of Dense Rubidium-Noble Gas Mixtures via Collisional Redistribution of Radiation  

E-print Network

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 D-line 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; Weitz, Martin; 10.1117/12.905897

2012-01-01

165

Some possibilities of using gas mixtures other than air in aerodynamic research  

NASA Technical Reports Server (NTRS)

A study is made of the advantages that can be realized in compressible-flow research by employing a substitute heavy gas in place of air. The present report is based on the idea that by properly mixing a heavy monatomic gas with a suitable heavy polyatomic gas, it is possible to obtain a heavy gas mixture which has the correct ratio of specific heats and which is nontoxic, nonflammable, thermally stable, chemically inert, and comprised of commercially available components. Calculations were made of wind-tunnel characteristics for 63 gas pairs comprising 21 different polyatomic gases properly mixed with each of three monatomic gases (argon, krypton, and zenon).

Chapman, Dean R

1956-01-01

166

Inflammable Gas Mixture Detection with a Single Catalytic Sensor Based on the Electric Field Effect  

PubMed Central

This paper introduces a new way to analyze mixtures of inflammable gases with a single catalytic sensor. The analysis technology was based on a new finding that an electric field on the catalytic sensor can change the output sensitivity of the sensor. The analysis of mixed inflammable gases results from processing the output signals obtained by adjusting the electric field parameter of the catalytic sensor. For the signal process, we designed a group of equations based on the heat balance of catalytic sensor expressing the relationship between the output signals and the concentration of gases. With these equations and the outputs of different electric fields, the gas concentration in a mixture could be calculated. In experiments, a mixture of methane, butane and ethane was analyzed by this new method, and the results showed that the concentration of each gas in the mixture could be detected with a single catalytic sensor, and the maximum relative error was less than 5%. PMID:24717635

Tong, Ziyuan; Tong, Min-Ming; Meng, Wen; Li, Meng

2014-01-01

167

Operation of limited streamer tubes with the gas mixture Ar + CO2 + n-pentane  

Microsoft Academic Search

The active detectors of the ALEPH hadron calorimeter at LEP consist of plastic streamer tubes developed in Frascati. The standard gas mixture for the operation of such devices is argon-isobutane (30\\/70). However, in underground experiments, for safety reasons, one has to reduce the hydrocarbon content. Therefore a study of the behaviour of streamer tubes operated with a Ar\\/CO2\\/n-pentane mixture has

G. Bagliesi; R. Baldini-Celio; G. Batignani; G. Bencivenni; G. G. Bologna; F. Bossi; U. Bottigli; C. Bradaschia; P. Campana; G. Capon; M. G. Catanesi; V. Chiarella; G. de Ninno; M. de Palma; B. D'Ettorre Piazzoli; M. Dreucci; G. Felici; L. Foà; A. Giassi; G. Iaselli; P. Laurelli; G. Maggi; G. Mannocchi; G. P. Murtas; G. Nicoletti; S. Nuzzo; P. Picchi; A. Ranieri; G. Raso; H. Rigoni; F. Romano; F. Ruggieri; S. Scapellato; G. Selvaggi; R. Tenchini; G. Zito

1988-01-01

168

Venus, Earth, Xenon  

NASA Astrophysics Data System (ADS)

Xenon has been regarded as an important goal of many proposed missions to Venus. This talk is intended to explain why. Despite its being the heaviest gas found in natural planetary atmospheres, there is more evidence that Xe escaped from Earth than for any element apart from helium: (i) Atmospheric Xe is very strongly mass fractionated (at about 4% per amu) from any known solar system source. This suggests fractionating escape that preferentially left the heavy Xe isotopes behind. (ii) Xe is underabundant compared to Kr, a lighter noble gas that is not strongly mass fractionated in air. (iii) Radiogenic Xe is strongly depleted by factors of several to ~100 compared to the quantities expected from radioactive decay of primordial solar system materials. In these respects Xe on Mars is similar to Xe on Earth, but with one key difference: Xe on Mars is readily explained by a simple process like hydrodynamic escape that acts on an initially solar or meteoritic Xe. This is not so for Earth. Earth's Xe cannot be derived by an uncontrived mass fractionating process acting on any known type of Solar System Xe. Earth is a stranger, made from different stuff than any known meteorite or Mars or even the Sun. Who else is in Earth's family? Comets? We know nothing. Father Zeus? Data from Jupiter are good enough to show that jovian Xe is not strongly mass-fractionated but not good enough to determine whether Jupiter resembles the Earth or the Sun. Sister Venus? Noble gas data from Venus are incomplete, with Kr uncertain and Xe unmeasured. Krypton was measured by several instruments on several spacecraft. The reported Kr abundances are discrepant and were once highly controversial. These discrepancies appear to have been not so much resolved as forgotten. Xenon was not detected on Venus. Upper limits were reported for the two most abundant xenon isotopes 129Xe and 132Xe. From the limited data it is not possible to tell whether Venus's affinities lie with the solar wind, or with the chondrites, with Earth, or with none of the above. Modern spacecraft mass spectrometers are at least 100-fold more sensitive to noble gases. Sending such an instrument to Venus may be the last best hope for decrypting what Earth's noble gases have been trying to tell us.

Zahnle, K. J.

2013-12-01

169

Computation of Hypersonic Shock Waves in Inert Gas Mixtures Using the Generalized Boltzmann Equation  

NASA Astrophysics Data System (ADS)

For numerical solution of the Generalized Boltzmann Equation (GBE) for simulating rarefied hypersonic flows in a gas mixture of multiple species, the GBE is formulated in the impulse space. The gas mixtures may consist of both monatomic gases and diatomic gases with arbitrary constituents, concentrations, and mass ratios. The conservative discrete ordinates method of Tcheremissine is applied to validate the solutions against the existing simulations for shock waves in an inert binary mixture of monatomic gases. The method is then exercised for various concentration ratios, mass ratios, and density ratios to evaluate its ability to simulate a wide range of binary gas mixtures. It is also applied to simulate two of the three primary constituents of air (N2, O2, Ar) in a binary mixture at 1:1 concentrations and at the relative concentrations found in air. These solutions can serve as validation test cases for other methods as well as an important building block in developing complex 3D simulations for shock waves in a mixture of multiple gases.

Wilson, Christopher D.; Agarwal, Ramesh K.; Tcheremissine, Felix G.

2011-05-01

170

Microwave-assisted generation of standard gas mixtures.  

PubMed

Microwave heating was employed for preparation of the standard gas of volatile organic compounds (VOCs) and semivolatile organic compounds (semi-VOCs) by using a 1000 W commercial domestic microwave oven and 1 L gas-sampling bulbs. The VOCs investigated were benzene, chloroform, 1,3-dichlorobenzene, tetrachloroethylene, toluene, and 1,1,2-trichloroethane, and the semi-VOCs used were the polychlorinated biphenyls (PCBs) PCB 1016 and PCB 1248. Since these weakly or nonpolar molecules are very poor absorbers of microwave energy, an appropriate amount of water was introduced to accept microwave radiation and act as the thermal source to accelerate their evaporation. The glass bulb may also contribute thermal energy to the VOCs/semi-VOCs by accepting microwave energy to a small degree. For 0.5 microL of liquid VOCs on 10 mg of glass wool, it was shown that 15 microL of H2O and 60 s of microwave heating yielded a very efficient evaporation [97.2-106.4%, compared with a classic method (Muller, L; Gorecki, T.; Pawliszyn, J. Fresenius' J. Anal. Chem. 1999, 364, 610-616)]. For 1 microL of PCB solution (1000 microg/mL in hexane), 15 microL of H2O and 90 s of microwave heating also provided a complete evaporation. The addition of water was particularly significant for microwave-assisted evaporation of PCBs because semi-VOCs are much more difficult to evaporate than VOCs. This developed microwave technique proved to be quite simple, powerful, rapid, accurate, and safe for the preparation of VOC/semi-VOC standard gas. Solid- phase microextraction combined with gas chromatography was used for the gas analysis. PMID:12038774

Xiong, Guohua; Pawliszyn, Janusz

2002-05-15

171

Steady-state temperature distribution within a Brayton rotating unit operating in a power conversion system using helium-xenon gas  

NASA Technical Reports Server (NTRS)

The Brayton rotating unit (BRU), consisting of a turbine, an alternator, and a compressor, was tested as part of a Brayton cycle power conversion system over a side range of steady state operating conditions. The working fluid in the system was a mixture of helium-xenon gases. Turbine inlet temperature was varied from 1200 to 1600 F, compressor inlet temperature from 60 to 120 F, compressor discharge pressure from 20 to 45 psia, rotative speed from 32 400 to 39 600 rpm, and alternator liquid-coolant flow rate from 0.01 to 0.27 pound per second. Test results indicated that the BRU internal temperatures were highly sensitive to alternator coolant flow below the design value of 0.12 pound per second but much less so at higher values. The armature winding temperature was not influenced significantly by turbine inlet temperature, but was sensitive, up to 20 F per kVA alternator output, to varying alternator output. When only the rotational speed was changed (+ or - 10% of rated value), the BRU internal temperatures varied directly with the speed.

Johnsen, R. L.; Namkoong, D.; Edkin, R. A.

1971-01-01

172

CO2 + N2O mixture gas hydrate formation kinetics and effect of soil minerals on mixture-gas hydrate formation process  

NASA Astrophysics Data System (ADS)

CO2 mitigation is one of the most pressing global scientific topics in last 30 years. Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by the Kyoto Protocol and its global warming potential (GWP) of one metric ton is equivalent to 310 metric tons of CO2. They have similar physical and chemical properties and therefore, mixture-gas (50% CO2 + 50% N2O) hydrate formation process was studied experimentally and computationally. There were no significant research to reduce N20 gas and we tried to make hydrate to mitigate N20 and CO2 in same time. Mixture gas hydrate formation periods were approximately two times faster than pure N2O hydrate formation kinetic in general. The fastest induction time of mixture-gas hydrate formation observed in Illite and Quartz among various soil mineral suspensions. It was also observed that hydrate formation kinetic was faster with clay mineral suspensions such as Nontronite, Sphalerite and Montmorillonite. Temperature and pressure change were not significant on hydrate formation kinetic; however, induction time can be significantly affected by various chemical species forming under the different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEQC, and used for the identification of hydrate formation characteristics in the suspensions. With the experimental limitations, a study on the molecular scale modeling has a great importance for the prediction of phase behavior of the gas hydrates. We have also performed molecular dynamics computer simulations on N2O and CO2 hydrate structures to estimate the residual free energy of two-phase (hydrate cage and guest molecule) at three different temperature ranges of 260K, 273K, and 280K. The calculation result implies that N2O hydrates are thermodynamically stable at real-world gas hydrate existing condition within given temperature and pressure. This phenomenon proves that mixture-gas could be efficiently applied to CO2 sequestration at potential sites and further investigations must be conducted to identify possible effects frequently found in natural geological environments and geo-environmental conditions at the site affecting the hydrate formation kinetics.

Enkh-Amgalan, T.; Kyung, D.; Lee, W.

2012-12-01

173

Xenon recirculation-purification with a heat exchanger  

Microsoft Academic Search

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-01-01

174

Effect of Gas Mixture on Plasma Jet Discharge Morphology  

Microsoft Academic Search

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

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

2011-01-01

175

Electron attachment, effective ionization coefficient, and electron drift velocity for CF 4 gas mixtures  

NASA Astrophysics Data System (ADS)

For tracking in a SSC experiment with wire chambers, CF 4 gas mixtures are very advantageous from the point of view of aging, drift velocity, and spatial resolution. However, they are also known to suffer from considerable electron attachment. This attachment can cause serious inefficiencies in the collection of electrons liberated near the anode wire, and causes broadening of the pulse-height spectrum for all ionization electrons. Two bench-top setups have been used to study electron attachment of CF 4 gas mixtures, and related properties such as the gas gain difference between single-electron avalanches and 55Fe X-ray initiated avalanches, the degradation of the energy resolution due to electron attachment, and the effective ionization coefficient overline?(? ? - ?) . A set of three prototype straw-tube modules each containing an 8 × 8 bundle of straws has been constructed and tested at a Fermilab test beam with various CF 4 gas mixtures. Some preliminary results on the drift velocity and drift time for these gas mixtures are reported.

Anderson, W. S.; Armitage, J. C.; Dunn, E.; Heinrich, J. G.; Lu, C.; McDonald, K. T.; Weckel, J.; Zhu, Y.

1992-12-01

176

On dynamics of imploding shock waves in a mixture of gas and dust particles  

E-print Network

In this paper, the generalized analytical solutions for one-dimensional adiabatic flow behind the imploding shock waves propagating in a dusty gas are obtained using the geometrical shock dynamics theory. The dusty gas is assumed to be a mixture of a perfect gas and spherically small solid particles, in which solid particles are continuously distributed. Shock jump relations given by Anand for a dusty gas are taken into consideration to explore the effects due to an increase in (i) the propagation distance from the centre of convergence, (ii) the mass fraction of solid particles in the mixture and (iii) the ratio of the density of solid particles to the initial density of the gas, on the shock velocity, pressure, temperature, density, velocity of mixture, speed of sound, adiabatic compressibility of mixture and the change-in-entropy across the shock front. The results provided a clear picture of whether and how the presence of solid particles influences the flow field behind the imploding shock front.

Anand, R K

2014-01-01

177

First Results from XENON100  

E-print Network

First Results from XENON100 For the XENON100 Collaboration Rafael F. Lang Columbia University rafael.lang@astro.columbia.edu #12;Rafael F. Lang (Columbia): First Results from XENON100 2 The XENON Università di Bologna Jiao Tong University Shanghai #12;Rafael F. Lang (Columbia): First Results from XENON

Weaver, Harold A. "Hal"

178

Variable-temperature cryogenic trap for the separation of gas mixtures  

NASA Technical Reports Server (NTRS)

The paper describes a continuous variable-temperature U-shaped cold trap which can both purify vacuum-line combustion products for subsequent stable isotopic analysis and isolate the methane and ethane constituents of natural gases. The canister containing the trap is submerged in liquid nitrogen, and, as the gas cools, the gas mixture components condense sequentially according to their relative vapor pressures. After the about 12 min required for the bottom of the trap to reach the liquid-nitrogen temperature, passage of electric current through the resistance wire wrapped around the tubing covering the U-trap permits distillation of successive gas components at optimal temperatures. Data on the separation achieved for two mixtures, the first being typical vacuum-line combustion products of geochemical samples such as rocks and the second being natural gas, are presented, and the thermal behavior and power consumption are reported.

Des Marais, D. J.

1978-01-01

179

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

180

Understanding and designing field asymmetric waveform ion mobility spectrometry separations in gas mixtures.  

PubMed

Field asymmetric waveform ion mobility spectrometry (FAIMS) has significant potential for post-ionization separations in conjunction with MS analyses. FAIMS fractionates ion mixtures by exploiting the fact that ion mobilities in gases depend on the electric field in a manner specific to each ion. Nearly all previous work has used pure gases, for which FAIMS fundamentals are understood reasonably well; however, unexpected phenomena observed in some gas mixtures (e.g., N(2)/CO(2)) but not in others (N(2)/O(2)) remain unexplained. Here, we introduce and experimentally test a universal model for FAIMS separations in mixtures, derived from formalisms that determine high-field mobilities in heteromolecular gases. Overall, the theoretical findings are consistent with data for N(2)/CO(2) (although quantitative discrepancies remain), while results for N(2)/O(2) fit Blanc's law, in agreement with measurements. Calculations for He/N(2) and He/CO(2) are also consistent with observations and suggest why adding He to the working gas generally enhances FAIMS performance. As predicted, mixtures of gases with extremely disparate molecular masses and collision cross sections, such as He/SF(6), exhibit spectacular non-Blanc effects, which greatly improve the resolution and peak capacity of technique. Understanding FAIMS operation in gas mixtures is expected to enable the rational design of media for both targeted and global analyses. PMID:15595881

Shvartsburg, Alexandre A; Tang, Keqi; Smith, Richard D

2004-12-15

181

Recovering Residual Xenon Propellant for an Ion Propulsion System  

NASA Technical Reports Server (NTRS)

Future nuclear-powered Ion-Propulsion- System-propelled spacecraft such as Jupiter Icy Moon Orbiter (JIMO) will carry more than 10,000 kg of xenon propellant. Typically, a small percentage of this propellant cannot be used towards the end of the mission because of the pressure drop requirements for maintaining flow. For large missions such as JIMO, this could easily translate to over 250 kg of unusable xenon. A proposed system, the Xenon Recovery System (XRS), for recovering almost all of the xenon remaining in the tank, would include a cryopump in the form of a condenser/evaporator that would be alternatively cooled by a radiator, then heated electrically. When the pressure of the xenon in the tank falls below 0.7 MPa (100 psia), the previously isolated XRS will be brought online and the gas from the tank would enter the cryopump that is initially cooled to a temperature below saturation temperature of xenon. This causes xenon liquefaction and further cryopumping from the tank till the cryopump is full of liquid xenon. At this point, the cryopump is heated electrically by small heaters (70 to 80 W) to evaporate the liquid that is collected as high-pressure gas (<7 MPa; 1,000 psia) in an intermediate accumulator. Check valves between the tank and the XRS prevent the reverse flow of xenon during the heating cycle. The accumulator serves as the high-pressure source of xenon gas to the Xenon Feed System (XFS) downstream of the XRS. This cycle is repeated till almost all the xenon is recovered. Currently, this system is being baselined for JIMO.

Ganapathi, Gani; Skakkottai, P.; wu, Jiunn Jeng

2006-01-01

182

Separation of gas mixtures using Co(II) carborane-based porous coordination polymersw  

E-print Network

Separation of gas mixtures using Co(II) carborane-based porous coordination polymersw Youn-Sang Bae adsorption.1 Porous coordination polymers (PCPs), also referred to as metal­organic frameworks (MOFs collapse under harsh conditions.4 To this end, we recently introduced an example of Co(II) carborane-based

183

EVALUATION OF THE EFFICIENCY OF INDUSTRIAL FLARES: H2S GAS MIXTURES AND PILOT ASSISTED FLARES  

EPA Science Inventory

The report is the fourth in a series on a research program which will result in quantification of emissions from, and efficiencies of, industrial flares. The report gives test data on the combustion efficiency and destruction efficiency of (1) gas mixtures containing H2S, and (2)...

184

A FORTRAN program for the determination of nozzle contours for rotational, non-homentropic gas mixtures  

NASA Technical Reports Server (NTRS)

A program was written which generates a nozzle contour and the complete flow field for two dimensional or axisymetric flows designed to exit parallel to the axis at uniform pressure. The flow is that of a rotational, non-homentropic gas mixture where viscous effects were neglected and the chemistry is assumed frozen. A description of the numerical program developed, is also described.

Kalben, P.

1977-01-01

185

Recent developments in parallel-grid, gas-scintillation proportional counters  

NASA Technical Reports Server (NTRS)

The problems of developing large-area, gas-scintillation proportional counters with high resolution are considered. It is found that simple large-area, parallel-grid proportional counters suffer from a variation in gain over the counter window. Some success has been achieved in overcoming this problem by focusing the charge cloud as it drifts into the multiplication region. Measurements are reported for various mixtures of argon and xenon as well as pure xenon.

Anderson, D. F.; Ku, W.; Mitchell, D. D.; Novick, R.; Wolff, R. S.

1977-01-01

186

Hovering performance of hummingbirds in hyperoxic gas mixtures.  

PubMed

Hummingbirds evolved during a period of decline in atmospheric oxygen concentration and currently encounter varying levels of oxygen availability along their elevational distribution. We tested the hypothesis that inspiration of hyperoxic gas increases hummingbird hovering performance when birds are simultaneously challenged aerodynamically. We measured the maximum duration of hovering flight while simultaneously monitoring the rate of oxygen consumption of ruby-throated hummingbirds (Archilochus colubris) in low-density heliox that was either normoxic (21% O2) or hyperoxic (35% O2). As air density decreased below 0.85 kg x m(-3), hummingbirds hovered significantly longer in hyperoxia than in normoxia, but the air density at which the birds could no longer sustain hovering flight was independent of oxygen concentration. At low air densities in hyperoxia flight trials, hummingbirds appeared to increase their rate of oxygen consumption relative to flight sequences at equivalent densities in normoxia trials, but these differences were not significant. We tested the hypothesis that hummingbirds can discriminate between environments that differ in oxygen concentration. In another density-reduction experiment, hummingbirds were allowed to choose between artificial feeders infused with either normoxic or hyperoxic gases. The hypothesis was not supported because birds failed to associate oxygen concentration with a particular feeder independently of air density. Supplemental oxygen thus yields increased hovering duration at intermediate air densities, but the minimum density at which birds can fly is limited exclusively by aerodynamic considerations. PMID:11441043

Altshuler, D L; Chai, P; Chen, J S

2001-06-01

187

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

188

Electron-beam sustained discharge in oxygen gas mixtures: singlet delta oxygen production for oxygen-iodine laser  

Microsoft Academic Search

Electric properties and spectroscopy of an e-beam sustained discharge (EBSD) in oxygen and oxygen gas mixtures at gas pressure up to 100 Torr were experimentally studied. The pulsed discharge in pure oxygen and its mixtures with noble gases was shown to be very unstable and characterized by low input energy. When adding small amount of carbon monoxide or hydrogen, the

Mikhail P. Frolov; Gordon D. Hager; Andrei A. Ionin; Yurii M. Klimachev; Igor V. Kochetov; Andrei A. Kotkov; John K. McIver; Anatolii P. Napartovich; Yurii P. Podmar'kov; Leonid V. Seleznev; Dmitrii V. Sinitsyn; Nikolai P. Vagin; Nikolay N. Yuryshev

2004-01-01

189

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.

1988-06-28

190

EUV Radiation of Xenon Plasma Streams Generated by Magnetoplasma I.E. Garkusha1  

E-print Network

EUV Radiation of Xenon Plasma Streams Generated by Magnetoplasma Compressor I.E. Garkusha1 , V generation lithography. In both approaches xenon has advantage to be used as working gas due to considerably. This paper presents the investigations xenon plasma streams generated by magnetoplasma compressor (MPC

Harilal, S. S.

191

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

192

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

193

The structure of variable property, compressible mixing layers in binary gas mixtures  

NASA Technical Reports Server (NTRS)

We present the results of a study of the structure of a parallel compressible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H2), helium (He), nitrogen (N2), oxygen (02), neon (Ne) and argon (Ar). Profiles of the variation of the Lewis and Prandtl numbers across the mixing layer for all thirty combinations of gases are given. It is shown that the Lewis number can vary by as much as a factor of eight and the Prandtl number by a factor of two across the mixing layer. Thus assuming constant values for the Lewis and Prandtl numbers of a binary gas mixture in the shear layer, as is done in many theoretical studies, is a poor approximation. We also present profiles of the velocity, mass fraction, temperature and density for representative binary gas mixtures at zero and supersonic Mach numbers. We show that the shape of these profiles is strongly dependent on which gases are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream.

Kozusko, F.; Grosch, C. E.; Jackson, T. L.; Kennedy, Christipher A.; Gatski, Thomas B.

1996-01-01

194

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

195

Mass spectrometer calibration over wide concentration ranges in multicomponent gas mixtures  

NASA Astrophysics Data System (ADS)

A quadrupole mass spectrometer (QMS) is used to measure the mixture composition of gas samples gathered in a novel burner configuration used to generate unstretched diffusion flames. The large variations of species concentration in the mixtures found in the burning chamber lead to accuracy problems due to the nonlinearities inherent to the instrument mode of operation. To obtain precise and real-time measurements, the sensitivity of the instrument is mapped to account for important changes in the sample composition. The implemented calibration procedure accounts for the concentration of the various species of interest in the burner (H2, He, H2O, CH4, O2, Ar, CO2) in mixtures containing up to five constituents, using up to one hundred reference mixtures. When necessary, calibration adjustments are performed using a small set of measurements to account for the effect of the drift of instrument sensitivity resulting from instrument wear or fouling. This procedure allows us to keep the relative error on the concentration of every species of interest below 5% for most of the mixtures while a classical calibration based on a limited number of reference mixtures often resulted in relative errors in excess of 50%.

Robert, Etienne

2010-02-01

196

A new apparatus for the measurement of physical adsorption of gas mixtures at elevated pressures  

NASA Astrophysics Data System (ADS)

The new apparatus described enables making simultaneously absolute measurements of physisorption, bulk density, and adsorption kinetics of multicomponent gas mixtures as a function of pressure up to 30 MPa. The method which combines the dynamic and the gravimetric methods is self-sufficient because it does not require complementary data. An in-line high-pressure chromatographic device directly measures the time evolution of the effluent flow composition (breakthrough curves). Results of adsorption, density, and adsorption kinetics at high pressures of the equimolar Ar-CH4 mixture on activated carbon are reported.

Malbrunot, P.; Vidal, D.; Vermesse, J.

1993-07-01

197

Characteristic of a PDP-based radiation detector in Xe-He mixture gas  

NASA Astrophysics Data System (ADS)

In this study, we have investigated a 2-dimensional gas detector based on plasma display technology as a candidate for the flat-panel radiation detector. Using the Geant4 and Garfield codes, that simulate the passage of particles through matter, we examined the dependence of X-ray absorption and multiplication factors on the Xe-He gas mixture. Prototype detectors, with four different gas mixtures, were designed and fabricated based on the results from the simulations. The performance of four detectors was evaluated by measuring the collected charge density, dark current density and sensitivity. The maximum collected charge occurred when the Xe 80%-He 20% gas mixture was 1.216 ?C/cm2 at -1800 V. The dark current of this detector varied between 0.124 and 0.321 nA/cm2 in the bias range of -300 to -1800 V, which is approximately one-third of the dark current density of an a-Se based detector, in this range. The sensitivity of Xe 80%-He 20% detector was 0.246 nC/mRcm2 at 0.61 V/?m. It is about a tenth lower than that of an a-Se based detector at 10 V/?m.

Eom, S.; Kang, J.; Lee, H.; Lee, K.

2013-04-01

198

Intermolecular polarizabilities in H2-rare-gas mixtures (H2-He, Ne, Ar, Kr, Xe): insight from collisional isotropic spectral properties.  

PubMed

The report presents results of theoretical and numerical analysis of the electrical properties related to the isotropic part of the polarizability induced by interactions within compounds built up of a hydrogen H2 molecule and a set of noble gas atoms, Rg, ranging from the least massive helium up to the heaviest xenon perturber. The Cartesian components of the collisional polarizabilities of the H2-Rg systems are found by means of the quantum chemistry methods and their dependence on the intermolecular distance is determined. On the basis of these data, the spherical, symmetry adapted components of the trace polarizability are derived in order to provide data sets that are convenient for evaluating collisional spectral profiles of the isotropic polarized part of light scattered by the H2-Rg mixtures. Three independent methods of numerical computing of the spectral intensities are applied at room temperature (295 K). The properties of the roto-translational profiles obtained are discussed in order to determine the role played by contributions corresponding to each of the symmetry adapted parts of the trace polarizability. By spreading the analysis over the collection of the H2-Rg systems, evolution of the spectral properties with the growing masses of the supermolecular compounds can be observed. PMID:25149794

G?az, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Maroulis, George; Haskopoulos, Anastasios

2014-08-21

199

Intermolecular polarizabilities in H2-rare-gas mixtures (H2-He, Ne, Ar, Kr, Xe): Insight from collisional isotropic spectral properties  

NASA Astrophysics Data System (ADS)

The report presents results of theoretical and numerical analysis of the electrical properties related to the isotropic part of the polarizability induced by interactions within compounds built up of a hydrogen H2 molecule and a set of noble gas atoms, Rg, ranging from the least massive helium up to the heaviest xenon perturber. The Cartesian components of the collisional polarizabilities of the H2-Rg systems are found by means of the quantum chemistry methods and their dependence on the intermolecular distance is determined. On the basis of these data, the spherical, symmetry adapted components of the trace polarizability are derived in order to provide data sets that are convenient for evaluating collisional spectral profiles of the isotropic polarized part of light scattered by the H2-Rg mixtures. Three independent methods of numerical computing of the spectral intensities are applied at room temperature (295 K). The properties of the roto-translational profiles obtained are discussed in order to determine the role played by contributions corresponding to each of the symmetry adapted parts of the trace polarizability. By spreading the analysis over the collection of the H2-Rg systems, evolution of the spectral properties with the growing masses of the supermolecular compounds can be observed.

G?az, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Maroulis, George; Haskopoulos, Anastasios

2014-08-01

200

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

201

Effects of xenon gas on generation and propagation of shock waves in the cavity of excimer laser  

Microsoft Academic Search

High repetition rate excimer lasers are expected for wide industrial application. The power of excimer laser, however, decreases rapidly in a higher repetition rate operation. Shock or acoustic waves, which are caused by the periodic pulse discharge, may limit the repetition rate of an excimer laser up to 2.5 kHz. Such waves cause inhomogeneity of gas density in the discharge

Shinichiroh Kosugi; Kazuo Maeno; Hiroki Honma

1993-01-01

202

Amplification and Scintillation Properties of Oxygen-Rich Gas Mixtures for Optical-TPC Applications  

E-print Network

We studied electron amplification and light emission from avalanches in oxygen-containing gas mixtures. The mixtures investigated in this work included, among others, CO2 and N2O mixed with Triethylamine (TEA) or N2. Double-Step Parallel Gap (DSPG) multipliers and THick Gas Electron Multipliers (THGEM) were investigated. High light yields were measured from CO2+N2 and CO2+TEA, though with different emission spectra. We observed the characteristic wave-length emission of N2 and of TEA and used a polymer wave-length shifter to convert TEA UV-light into the visible spectrum. The results of these measurements indicate the applicability of optical recording of ionizing tracks in a TPC target-detector designed to study the cross section of the 16O(g,a)12C reaction, a central problem in nuclear astrophysics.

L. Weissman; M. Gai; A. Breskin; R. Chechik; V. Dangendorf; K. Tittelmeier; H. R. Weller

2006-02-27

203

Preparation of neutron-activated xenon for liquid xenon detector calibration  

NASA Astrophysics Data System (ADS)

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a 5-day activation of natural xenon gas with a 252Cf (4×10n/s) source, the activities of two gamma ray lines at 164 and 236 keV, from 131mXe and 129mXe metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35, 100 and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

Ni, K.; Hasty, R.; Wongjirad, T. M.; Kastens, L.; Manzur, A.; McKinsey, D. N.

2007-11-01

204

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration  

E-print Network

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

Ni, K; Wongjirad, T M; Kastens, L; Manzur, A; McKinsey, D N

2007-01-01

205

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration  

E-print Network

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

K. Ni; R. Hasty; T. M. Wongjirad; L. Kastens; A. Manzur; D. N. McKinsey

2007-09-27

206

Gas viscosities of azeotropic mixtures of the halogenated hydrocarbons R500, R502, and R503  

Microsoft Academic Search

Gas viscosities of azeotropic mixtures R500 (dichlorodifluoromethane (R12)-1, 1-difluoroethane (R152a)), R 502 (chlorodifluoromethane (R22)-chloropentafluoroethane (R115)), and R503 (chlorotrifluoromethane (R13)-trifluoromethane (R23)) were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa. Two empirical equations for the viscosities were obtained; one is for the atmospheric viscosities as a function of temperature, and the other

Mitsuo Takahashi; Chiaki Yokoyama; Shinji Takahashi

1988-01-01

207

Emission analysis of a compressed natural gas directinjection engine with a homogenous mixture  

Microsoft Academic Search

In an era in which environmental pollution and depletion of world oil reserves are of major concern, emissions produced by\\u000a automotive vehicles need to be controlled and reduced. An ideal solution is to switch to a cleaner fuel such as natural gas,\\u000a which generates cleaner emissions. In addition, control over the in-cylinder air-fuel mixture can be best achieved through\\u000a a

S. Abdullah; W. H. Kurniawan; M. Khamas; Y. Ali

2011-01-01

208

Life cycle greenhouse emissions of compressed natural gas–hydrogen mixtures for transportation in Argentina  

Microsoft Academic Search

We have developed a model to assess the life cycle greenhouse emissions of compressed natural gas–hydrogen (CNG–H2) mixtures used for transportation in Argentina. The overall fuel life cycle is assessed through a well-to-wheel (WTW) analysis for different hydrogen generation and distribution options. The combustion stage in road vehicles is modeled using the COPERT IV model. Hydrogen generation options include classical

P. Martínez; L. Dawidowski; D. Gómez; D. Pasquevich

2010-01-01

209

Electron Density Measurements in UV-Preionized XeCl and CO2 Laser Gas Mixtures  

Microsoft Academic Search

A Langmuir probe technique has been used to measure electron densities and temperatures in UV-preionized XeCl excimer and CO2 laser gas mixtures in a laser tube. For this experiment, only pin electrodes (preionization sparks) were operated with no discharge between the main electrodes. The measured electron densities were about 108 cm-3 in both the excimer and CO2 laser gases, compared

Shigeyuki Takagi; Saburo Sato; Tatsumi Goto

1989-01-01

210

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

211

Limits to flight energetics of hummingbirds hovering in hypodense and hypoxic gas mixtures.  

PubMed

Hovering hummingbirds offer a model locomotor system for which analyses of both metabolism and flight mechanics are experimentally tractable. Because hummingbirds exhibit the highest mass-specific metabolic rates among vertebrates, maximum performance of hovering flight represents the upper limit of aerobic locomotion in vertebrates. This study evaluates the potential constraints of flight mechanics and oxygen availability on maximum flight performance. Hummingbird flight performance was manipulated non-invasively using air and gas mixtures which influenced metabolism via variable oxygen partial pressure and/or altered flight mechanics via variable air densities. Limits to the locomotor capacity of hovering ruby-throated hummingbirds (Archilochus colubris) were unequivocally indicated by aerodynamic failure in either air/helium or air/heliox mixtures. Air/helium mixtures are hypodense and hypoxic; failure to sustain hovering flight occurred at 63% of the density of sea-level air and at an oxygen concentration of 12%. Air/heliox mixtures are hypodense but normoxic; failure in hovering occurred at 47% of sea-level air density. Thus, hummingbirds demonstrated considerable power reserves in hovering flight as well as hypoxic tolerance. In air/helium mixtures, hovering was limited by oxygen supply and not by flight mechanics. Birds hovering in air/helium mixtures increased their mechanical power output but not their rate of oxygen consumption. By contrast, birds hovering in air/heliox mixtures increased both mechanical performance and metabolic expenditure. Under hypoxia, hovering hummingbirds demonstrated non-negligible, but still limited, capacities for anaerobic metabolism and/or oxygen storage. Depending on the physical context, hummingbird flight performance can therefore be limited by oxygen availability or by flight aerodynamics. PMID:8896366

Chai, P; Dudley, R

1996-10-01

212

A general stagnation-point convective heating equation for arbitrary gas mixtures  

NASA Technical Reports Server (NTRS)

The stagnation-point convective heat transfer to an axisymmetric blunt body for arbitrary gases in chemical equilibrium was investigated. The gases considered were base gases of nitrogen, oxygen, hydrogen, helium, neon, argon, carbon dioxide, ammonia, and methane and 22 gas mixtures composed of the base gases. Enthalpies ranged from 2.3 to 116.2 MJ/kg, pressures ranged from 0.001 to 100 atmospheres, and the wall temperatures were 300 and 1111 K. A general equation for the stagnation-point convective heat transfer in base gases and gas mixtures was derived and is a function of the mass fraction, the molecular weight, and a transport parameter of the base gases. The relation compares well with present boundary-layer computer results and with other analytical and experimental results. In addition, the analysis verified that the convective heat transfer in gas mixtures can be determined from a summation relation involving the heat transfer coefficients of the base gases. The basic technique developed for the prediction of stagnation-point convective heating to an axisymmetric blunt body could be applied to other heat transfer problems.

Sutton, K.; Graves, R. A., Jr.

1971-01-01

213

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

DOEpatents

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.; Bourcier, William L.

2014-08-19

214

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

DOEpatents

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

215

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

NASA Astrophysics Data System (ADS)

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 that the J-T cycle is an efficient application of mixed gas working fluids, being very similar to a vapor-compression cycle utilized in household refrigerants. The simplicity and viability of a J-T design and the associated minimal heat losses compensate for theoretical efficiency ratio of Stirling-type machines. Simultaneously, the J-T machines are never restricted in terms of output power and contain no moving parts in the cold zone resulting in minimal vibration during operation. The effective cooling of these systems allows parallel cooling of multiple objects. Finally in long-life system designs these cryocooler systems are feasibly coupled with phase-transition thermal storage accumulators. The application of such J-T systems is especially efficient under space conditions, due to the fact that there is an option to use at low temperatures a radiation release unit for the outlet of compression heat and for preliminary cooling of the system. This is not possible for terrestrial applications. Particularly, obtaining the -10 to 100 (C temperature range is feasible through the use of low As/(( - coefficient coatings; shade screens; or radiator unit orientations. Computational and experimental research has provided us high efficiency gas-mixture J-T cryocooler results between 60 to 100K cooling temperatures. We have actual space systems which were tested and operated for 80-90 K with efficiencies of 20 to 25 W/W. The authors of this research have studied various gas mixtures as candidates for use with simple J-T single contour J-T systems. We have seen resultant reduction of energy consumption by 2-3 times and decreases in temperatures from the 30-60( C range to -10 to 10( C range. We have also seen a dramatic reduction in the working pressure and the P/P pressure ratios within the cycle. We have gradually evolved into the application of simpler and more reliable working mixtures and employed more reliable single-stage compressors. In addition, the use of J-T contour gas mixtures for pre-cooling down to 35-40 K temperatures results in higher efficiency 2-stage J-T cryocoolers with similar overall results to the single stage systems.

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

216

The promising gas-dynamic schemes of vacuum deposition from the supersonic gas mixture flows  

Microsoft Academic Search

Gas jet deposition (GJD) becomes promising method of thin film and nanoparticle deposition. This paper is focused on elaboration of new methods of GJD based on different gas dynamic schemes of flow formation and interaction with substrate. Using direct statistical simulation method, the analysis was performed for: a) interaction of the jet from the sonic nozzle with a substrate; b)

R. V. Maltsev; A. K. Rebrov

2008-01-01

217

Methodology of gas adsorption process design. Separation of propane\\/propylene and n\\/iso-paraffins mixtures  

Microsoft Academic Search

The general guidelines for developing a gas separation process based on adsorption are reviewed. Two important industrial cases based on adsorption processes are selected: the separation of propane\\/propylene mixtures and n\\/iso-paraffins mixtures. The 13X zeolite and Ag+-Amberlyst were used as adsorbent for propane\\/propylene mixture taking into account information from the open literature. The 5A zeolite was selected for n\\/iso-paraffins system;

José A. C. Silva; F. Avelino da Silva; Alirio E. Rodrigues

1999-01-01

218

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

219

Perceptual Characterization and Analysis of Aroma Mixtures Using Gas Chromatography Recomposition-Olfactometry  

PubMed Central

This paper describes the design of a new instrumental technique, Gas Chromatography Recomposition-Olfactometry (GC-R), that adapts the reconstitution technique used in flavor chemistry studies by extracting volatiles from a sample by headspace solid-phase microextraction (SPME), separating the extract on a capillary GC column, and recombining individual compounds selectively as they elute off of the column into a mixture for sensory analysis (Figure 1). Using the chromatogram of a mixture as a map, the GC-R instrument allows the operator to “cut apart" and recombine the components of the mixture at will, selecting compounds, peaks, or sections based on retention time to include or exclude in a reconstitution for sensory analysis. Selective recombination is accomplished with the installation of a Deans Switch directly in-line with the column, which directs compounds either to waste or to a cryotrap at the operator's discretion. This enables the creation of, for example, aroma reconstitutions incorporating all of the volatiles in a sample, including instrumentally undetectable compounds as well those present at concentrations below sensory thresholds, thus correcting for the “reconstitution discrepancy" sometimes noted in flavor chemistry studies. Using only flowering lavender (Lavandula angustifola ‘Hidcote Blue’) as a source for volatiles, we used the instrument to build mixtures of subsets of lavender volatiles in-instrument and characterized their aroma qualities with a sensory panel. We showed evidence of additive, masking, and synergistic effects in these mixtures and of “lavender' aroma character as an emergent property of specific mixtures. This was accomplished without the need for chemical standards, reductive aroma models, or calculation of Odor Activity Values, and is broadly applicable to any aroma or flavor. PMID:22912722

Johnson, Arielle J.; Hirson, Gregory D.; Ebeler, Susan E.

2012-01-01

220

Using an 80% CF4+20% CO2 gas mixture to recover aged anode wires in proportional chambers  

NASA Astrophysics Data System (ADS)

A technique to recover a gas proportional counter with an aged anode wire using a glow discharge in an 80%CF4+20%CO2 gas mixture, has been developed and tested. Studies of aging effects were carried out under sustained irradiation by an intense 90Sr ?-source of straw proportional counters operated with a 60%Ar+30%CO2+10%CF4 gas mixture. Special attention was paid to the aging mechanism of the anode wires. Our experience showed that using a given gas mixture the swelling of the anode wires is a typical mode of aging that leads to degradation of the gas gain. The proposed method restores the gas gain and the signal amplitude in the damaged zone of the wire. SEM/XEM analysis confirmed that the tungsten oxide deposits have been removed.

Gavrilov, G. E.; Aksenov, D. A.; Conti, R.; Fetisov, A. A.; Krivchitch, A. G.; Maysuzenko, D. A.; Shvecova, N. Yu.; Vakhtel, V. M.

2012-12-01

221

Effect of carbon isotopic variations on measured CO2 abundances in reference gas mixtures  

NASA Astrophysics Data System (ADS)

Changes in the Earth's climate caused by global warming are a looming problem that poses serious challenges not only for our generation but for future generations. An accurate determination of CO2 gas plays a critical role in this field of research. The measurement of greenhouse gases is pivotal to understanding the changes in Earth's climate and needs to be carried out with a high degree of accuracy. Precision measurements on a 0.1 ?mol/mol scale may provide research data for precisely monitoring the continuing changes that the planet is undergoing. The World Meteorological Organization (WMO) has recommended that carbon dioxide concentrations in air can be measured by comparing these with national reference gases using a nondispersive infrared (NDIR) analyzer to standardize international data. The CO2 molecules absorb the distinctive resonant frequencies in IR spectrometers. The NDIR analyzers usually use narrow band path filter to determine 12CO2 in all carbon dioxide molecules, which can possibly ignore the measurement of 13CO2 partially or totally. However, if the carbon isotopic abundances of CO2 samples deviate from those in standard CO2 gas, the NDIR measurement will not be exact. For accurate measurements, producers of reference gas mixtures either must use gas with natural isotopic abundances, or report the isotopic abundances of CO2. In order to document shifts based on isotopic variability, we prepared artificial air as CO2 reference gas mixtures gravimetrically with CO2 having different carbon isotopic signatures to study the resulting isotopic variations. We used different ?13C values of two CO2 source gases, A and B, corresponding to -41.97‰ and -14.88‰, respectively, which were measured using an isotope ratio mass spectrometer. One set of reference gas mixtures (A1 to A5) was prepared from the CO2 source of ?13C = -41.97‰, and the other set of reference gas mixtures (B1, B2) was prepared from that of ?13C = -14.88‰. The CO2 abundances of the two sets of mixtures were compared by using NDIR. The reproducibility test for the set A showed that the data are consistent within uncertainty (calibration line was obtained by the best secondary polynomial least squares fit). The uncertainty of CO2 concentration in the reference gas mixtures are 0.06 ?mol/mol with a 95% confidence level. The reproducibility of the NDIR measurement is 0.012 ?mol/mol (standard deviation). The difference between the set A (A1 to A5) and set B (B1, B2) was found to be 0.17 ± 0.01 ?mol/mol, which is in excellent agreement with the theoretically predicted value of 0.17 ?mol/mol.

Lee, Jee-Yon; Yoo, Hee-Soo; Marti, Kurt; Moon, Dong Min; Lee, Jin Bok; Kim, Jin Seog

2006-03-01

222

Separation of Fischer-Tropsch catalyst/wax mixtures using dense gas extraction  

SciTech Connect

The separation of a Fischer-Tropsch catalyst from wax products is an important issue when the synthesis is conducted in a slurry bubble column reactor. This paper describes a new technique based on dense gas extraction of the soluble hydrocarbon components from the insoluble catalyst particles using light hydrocarbons as propane, butane, and pentane as the solvent. The extractions were conducted in a continuous unit operated near the critical point of the extraction gas on a catalyst/wax mixture containing about 4.91 wt% catalyst. The catalyst-free wax was collected in the second stage collector while the catalyst and some insoluble wax components were collected in the first stage collector. The yield of catalyst-free wax was about 60 wt% of the feed mixture. The catalyst content of the catalyst/wax mixture in the first stage was about 14.8 wt%. The catalyst content in the second stage collector was less than 1 part in 100,000.

Eyring, M.W.; Rohar, P.C.; Hickey, R.F. [Dept. of Energy, Pittsburgh, PA (United States)] [and others

1995-12-01

223

Separation of Fischer-Tropsch catalyst/wax mixtures using dense gas extraction  

SciTech Connect

The separation of a Fischer-Tropsch catalyst from wax products is an important issue when the synthesis is conducted in a slurry bubble column reactor. This paper describes a new technique based on dense gas extraction of the soluble hydrocarbon components from the insoluble catalyst particles using light hydrocarbons as propane, butane, and pentane an the solvent. The extractions were conducted in a continuous unit operated near the critical point of the extraction gas on a catalyst/wax mixture containing about 4.91 wt% catalyst. The catalyst-free wax was collected in the second stage collector while the catalyst and some insoluble wax components were collected in the first stage collector. The yield of catalyst-free wax was about 60 wt% of the food mixture. The catalyst content of the catalyst/wax mixture in the first stage was about 14.8 wt%. The catalyst content in the second stage collector was less than 1 part in 100,000.

Eyring, M.W.; Rohar, P.C.; Hickey, R.F.; White, C.M. [PETC, Pittsburgh, PA (United States); Quiring, M.S. [Kerr-McGee Technical Center, Oklahoma City, OK (United States)

1995-12-31

224

Low-temperature electrical discharge through solid xenon  

NASA Astrophysics Data System (ADS)

A uniform self-sustained electrical discharge through solid xenon is realized and studied. The multiplication of electrons proceeds in the noble gas above the xenon crystal interface, whereas a positive feedback is realized on account of multiple exciton formation by excess electrons drifting through the crystal: molecular excitons emit VUV photons which knock out secondary electrons from photosensitive cathode. The discharge is stimulated by a short electrical spark along the sample axes. The electrical properties of the discharge and the electroluminescence spectra of solid xenon in the UV and visible are studied. Electrical discharge in solid xenon proves to be an effective source of UV radiation and a convenient tool for studying processes involving excitons and electrons in solid xenon at high pressures.

Gordon, E. B.; Matyushenko, V. I.; Sizov, V. D.; Smirnov, B. M.

2008-11-01

225

Acoustic waves in multifractional gas mixture with the inclusion of different materials and dimensions without Phase Transformations  

NASA Astrophysics Data System (ADS)

The propagation of acoustic waves in mixtures of gas and particle fractions of different materials and sizes is studied. A mathematical model is presented, the dispersion equation is obtained, dispersion curves are calculated. The influence of the particle size and the parameters of the dispersed phase for multifractional gas mixture with ice particles, aluminum and sand on dissipation and dispersion of sound waves is analyzed. A comparison with experiment is conducted.

Gubaidullin, D. A.; Teregulova, E. A.

2014-11-01

226

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

2009-10-01

227

Discrete velocity computations with stochastic variance reduction of the Boltzmann equation for gas mixtures  

NASA Astrophysics Data System (ADS)

We extend a variance reduced discrete velocity method developed at UT Austin [1, 2] to gas mixtures with large mass ratios and flows with trace species. The mixture is stored as a collection of independent velocity distribution functions, each with a unique grid in velocity space. Different collision types (A-A, A-B, B-B, etc.) are treated independently, and the variance reduction scheme is formulated with different equilibrium functions for each separate collision type. The individual treatment of species enables increased focus on species important to the physics of the flow, even if the important species are present in trace amounts. The method is verified through comparisons to Direct Simulation Monte Carlo computations and the computational workload per time step is investigated for the variance reduced method.

Clarke, Peter; Varghese, Philip; Goldstein, David

2014-12-01

228

High-accuracy P-p-T measurements of pure gas and natural gas like mixtures using a compact magnetic suspension densimeter  

E-print Network

Control SNG3 Synthetic natural gas mixture SNG5 Synthetic natural gas mixture SSR Solid State Relay T Tee fitting Ta Tantalum Ti Titanium TLP Tension Leg Platform V Valve ZP Zero Point Greek letters ? Temperature...-based composite material consisting of a large variety of organic and inorganic compounds including alumina, silica, ferric oxides, magnesium oxides etc. It is a porous material with polymeric character consisting of aromatic and hydro-aromatic units connected...

Ejaz, Saquib

2007-09-17

229

Evaluation of the age of landfill gas methane in landfill gas-natural gas mixtures using co-occurring constituents.  

PubMed

At a municipal solid waste landfill in southern California (USA) overlying a natural gas reservoir, methane was detected at concentrations of up to 40% (by volume) in perimeter soil gas probes. Stable isotope and (14)C values of methane together with gas composition (major components and volatile organic compounds) data were evaluated to assess the relative contributions of landfill gas and natural gas to the measured methane concentrations. The data was further used to estimate the residence time of the landfill gas in the probes. Results showed that up to 37% of the measured methane was derived from landfill gas. In addition, the landfill gas in the probe samples has undergone extensive alteration due to dissolution of carbon dioxide in pore water. Data further indicates that the measured methane was released from the waste approximately 1.2 to 9.4 years ago, rather than representing evidence of an ongoing release. PMID:23660592

Kerfoot, Henry B; Hagedorn, Benjamin; Verwiel, Mark

2013-06-01

230

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

2013-07-01

231

Precision measurement of timing RPC gas mixtures with laser-beam induced electrons  

NASA Astrophysics Data System (ADS)

The main goals of a new test facility at Helmholtz-Zentrum Dresden-Rossendorf are precision measurements of the electron drift velocity and the Townsend coefficient of gases at atmospheric pressure in the strongest ever used homogenous electrical fields and the search for new RPC gas mixtures to substitute the climate harmful Freon. Picosecond UV laser pulses were focused into a sub-millimeter gas gap to initialize a defined tiny charge. These gaps are formed by electrodes of low-resistive ceramics or high-resistive float glass. The charge multiplication occurs in a strong homogeneous electric field of up to 100 kV/cm. Electron-ion pairs were generated in a cylindrical micro-volume by multi-photon ionization. The laser-pulse repetition rate ranges from 1 Hz to a few kHz. The RPC time resolution has been measured for different gases. First results of the Townsend coefficient at 100 kV/cm show a strong disagreement between the present measurement and Magboltz simulations for the typical timing RPC gas mixture C2F4H2/SF6/i-C4H10, while the measured electron drift velocities are in a good agreement with the model predictions.

Naumann, L.; Siebold, M.; Kaspar, M.; Kämpfer, B.; Kotte, R.; Laso Garcia, A.; Löser, M.; Schramm, U.; Wüstenfeld, J.

2014-10-01

232

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

233

"Liquid Xenon R&D for Future Large-Scale Dark-Matter Detectors" , D B Cline1  

E-print Network

1 "Liquid Xenon R&D for Future Large-Scale Dark-Matter Detectors" M Atac1 , D B Cline1 , K T Mc in the direct observation of nuclear recoils. The ZEPLIN-II detector (with 35-kg of liquid xenon medium), which. These tests will include: 1. photon amplification in liquid and gas xenon using a CsI internal photo

McDonald, Kirk

234

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b  

E-print Network

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b , Luxi Li a,b , C. M ionization measurements of various high-n molecular Rydberg states doped into argon, krypton and xenon, krypton and xenon from the dilute gas up to the density of the triple point liquid, on both critical

Findley, Gary L.

235

A computer program for calculation of spectral radiative properties of gas mixtures  

NASA Technical Reports Server (NTRS)

A computer code is described whereby calculations of radiative properties of gas mixtures may be made. The program is arranged so that distinct radiative processes for each species are computed in individual subroutines. Provision is made for calculating radiative properties in nonequilibrium situations - separate rotational, vibrational, and electronic temperatures may be used. These features should provide a flexibility not currently available in such programs. The basic equations and the program listing in FORTRAN 4 language are presented. Sample calculations are given for high temperature air and carbon dioxide and are compared to calculations made with previously developed programs.

Nealy, J. E.

1975-01-01

236

Asymptotic modelling of the axisymmetric flow of a binary gas mixture in a circular microchannel  

NASA Astrophysics Data System (ADS)

In order to decrease the computation time, the development of asymptotic models describing gas flows in microchannels is an interesting alternative to DSMC simulations. In this contribution, our purpose is to model the axisymmetric flow of a mixture of two compressible gases in circular microchannels. The flow is in the slip regime that is at low Mach numbers and at low to moderate Knudsen numbers. The model is derived from Navier-Stokes equations and provides explicitly the longitudinal velocities in term of the pressures that are computed from a first order set of differential equations. The results are in good agreement with DSMC simulations.

Croizet, C.; Gatignol, R.

2014-12-01

237

Gas viscosities of azeotropic mixtures of the halogenated hydrocarbons R500, R502, and R503  

SciTech Connect

Gas viscosities of azeotropic mixtures R500 (dichlorodifluoromethane (R12)-1, 1-difluoroethane (R152a)), R 502 (chlorodifluoromethane (R22)-chloropentafluoroethane (R115)), and R503 (chlorotrifluoromethane (R13)-trifluoromethane (R23)) were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa. Two empirical equations for the viscosities were obtained; one is for the atmospheric viscosities as a function of temperature, and the other is for the viscosities in the whole range of the present measurement as a function of temperature and density.

Takahashi, M.; Yokoyama, C.; Takahashi, S.

1988-07-01

238

Quenching of Particle-Gas Combustible Mixtures Using Electric Particulate Suspension (EPS) and Dispersion Methods  

NASA Technical Reports Server (NTRS)

A cooperative study is being carried out between Iowa State University and McGill University. The new study concerns wall and particle quenching effects in particle-gas mixtures. The primary objective is to measure and interpret flame quenching distances, flammability limits, and burning velocities in particulate suspensions. A secondary objective is to measure particle slip velocities and particle velocity distribution as these influence flame propagation. Two suspension techniques will be utilized and compared: (1) electric particle suspension/EPS; and (2) flow dispersion. Microgravity tests will permit testing of larger particles and higher and more uniform dust concentrations than is possible in normal gravity.

Colver, Gerald M.; Goroshin, Samuel; Lee, John H. S.

2001-01-01

239

Effects of temperature on the carbonation of flue gas desulphurization gypsum using a CO2/N2 gas mixture.  

PubMed

The carbonation of flue gas desulphurization (FGD) gypsum using a CO2/N2 gas mixture was investigated to study the feasibility of using the flue gas directly in the gypsum carbonation. The effect of the reaction temperature on the carbonation reaction and the carbonation conversion efficiency of the samples were considered. In this study, the carbonation conversion efficiency was calculated using a new method for decreasing the error range from a sample containing unreacted gypsum. The carbonation reaction at 40°C was nearly twice as fast as the reaction at room temperature. In addition, the carbonation conversion efficiency at 40°C (96%) was nearly the same as that at room temperature. However, the efficiency decreased significantly with temperature, especially above 60°C. It can, therefore, be concluded that the direct use of flue gas in gypsum carbonation is most feasible at 40°C. The temperature of carbonation strongly affected the CaCO3 polymorphs and the morphological characteristics. Calcite with various shapes was the dominant (40-90%) phase at all temperatures. At temperatures below 40°C, spherical-shaped vaterite was pronounced, while needle-flower-shaped aragonite was dominant at temperatures above 80°C. PMID:25409589

Lee, Myung Gyu; Ryu, Kyung Won; Chae, Soo Chun; Jang, Young Nam

2015-01-01

240

Richtmyer-Meshkov instability in dilute gas-particle mixtures with re-shock  

NASA Astrophysics Data System (ADS)

The Richtmyer-Meshkov instability (RMI) is investigated in a dilute gas-particle mixture using three-dimensional numerical simulations. This work extends an earlier two-dimensional study [S. Ukai, K. Balakrishnan, and S. Menon, "On Richtmyer-Meshkov instability in dilute gas-particle mixtures," Phys. Fluids 22, 104103 (2010)] to a larger parameter space consisting of variations in the mass loading and the particle size as well as considering both single-mode and multi-mode interface initializations. In addition, the effect of the presence of particles on re-shock RMI is also investigated. Single-phase numerical predictions of the mixing layer growth-rate are shown to compare well to both experimental and theoretical results. In a dilute gas-particle mixture, the initial growth-rate of RMI shows similar trends compared to previous work; however, the current numerical predictions show that there is an observable increase, not previously predicted, in the growth of the mixing layer at higher mass loadings. For the range of cases considered, an increase as much as 56% is observed. This increase is attributed to additional vorticity production in the mixing layer resulting from inter-phase momentum coupling. Moreover, the presence of particles introduces a continuous drag on the gas-phase resulting in a delay in the time at which re-shock occurs. This delay, which is observed to be as much as 6%, is largest for higher initial mass loadings and smaller particle radii and has a corresponding effect on both the growth-rate of the mixing-layer after re-shock and the final width of the mixing layer. A new semi-analytical correlation is developed and verified against the numerical data to predict the re-shocked RMI growth-rate in dilute gas-particle flows. The correlation shows that the re-shock RMI growth-rate is linearly proportional to the velocity jump at re-shock, the molecular mixing fraction, and the multi-phase Atwood number. Depending on the initial mass loading and particle radii, the re-shock RMI growth-rates were observed to be reduced by as much as 48% in some cases with variations of around 26% in the width of the mixing layer after re-shock.

Schulz, J. C.; Gottiparthi, K. C.; Menon, S.

2013-11-01

241

Comparison of the optoacoustic and Hg tracer methods for the study of energy-transfer processes in gas mixtures  

Microsoft Academic Search

Rates of energy transfer from vibrationally excited SFâ and pentafluorobenzene to argon in the gas phase have been studied by using the Hg tracer technique and time-resolved optoacoustics. These two techniques which rely on fundamentally different physical principles were found to give equivalent results. The implications for the study of energy-transfer processes in gas mixtures are discussed.

Timothy J. Wallington; Walter Braun; Kenneth M. Beck; Robert J. Gordon

1988-01-01

242

The McCormack model for gas mixtures: Heat transfer in a plane channel R. D. M. Garcia  

E-print Network

-gas mix- ture described by the McCormack model, and so some of our introductory material here is repeatedThe McCormack model for gas mixtures: Heat transfer in a plane channel R. D. M. Garcia HSHCormack kinetic model. The solution yields for the general (specular-diffuse) case of Maxwell boundary conditions

Siewert, Charles E.

243

Transport Properties of He-N{sub 2} Binary Gas Mixtures for CBC Space Applications  

SciTech Connect

In order to reduce the size and mass of the single-shaft turbo-machines, with little impact on the size of the heat transfer components in the CBC loop, He-Xe binary mixture with a molecular weight of 40 g/mole has been the working fluid of choice in space nuclear reactor power systems with Close Brayton Cycle (CBC) for energy conversion. This working fluid is also a suitable coolant for the fission reactors heat source designed with fast neutron energy spectra. For space nuclear reactors with thermal neutron energy spectra, however, the high capture neutron cross-section of Xe will reduce the beginning-of-life excess reactivity of the reactor, decreasing its effective operation lifetime. In addition, the neutron activation of Xe in the reactor will introduce a radioactivity source term in the CBC loop. Alternative working fluids with no activation concerns and comparable performance are N{sub 2} and the binary mixtures of He-N{sub 2}. This paper calculates the transport properties of these working fluids and compares their values to those of noble gas binary mixtures at the temperatures and pressures expected in CBC space reactor power system applications. Also investigated is the impact of using these working fluids on the pressure losses, heat transfer coefficient, and the aerodynamic loading of the blades in the CBC turbo-machines.

Tournier, Jean-Michel P.; El-Genk, Mohamed S. [Institute for Space and Nuclear Power Studies and Chemical and Nuclear Engineering Department, University of New Mexico, Albuquerque, NM 87131 (United States)

2008-01-21

244

Gas energy meter for inferential determination of thermophysical properties of a gas mixture at multiple states of the gas  

DOEpatents

A gas energy meter that acquires the data and performs the processing for an inferential determination of one or more gas properties, such as heating value, molecular weight, or density. The meter has a sensor module that acquires temperature, pressure, CO2, and speed of sound data. Data is acquired at two different states of the gas, which eliminates the need to determine the concentration of nitrogen in the gas. A processing module receives this data and uses it to perform a "two-state" inferential algorithm.

Morrow, Thomas B. (San Antonio, TX); Kelner, Eric (San Antonio, TX); Owen, Thomas E. (Helotes, TX)

2008-07-08

245

The XENON100 Dark Matter Experiment: Initial Performance and Projected Sensitivity  

NASA Astrophysics Data System (ADS)

The XENON Dark Matter Project aims at the direct detection of WIMPs (Weakly Interacting Massive Particles) with dual phase (liquid/gas) xenon time projection chambers (LXeTPCs). 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 150 kg of xenon. The detector, mounted in the same passive shield used for XENON10 at the Gran Sasso Underground Laboratory, is currently undergoing gamma calibration. Based on a similar design as XENON10, XENON100 features an increase in fiducial target mass of a factor of 10, with an overall background rate about 100 times lower. We report on the status of this development and discuss the projected sensitivity reach for dark matter detection.

Aprile, Elena

2008-04-01

246

A Xenon Condenser with a Remote Liquid Storage Vessel  

E-print Network

We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. We find that an external xenon gas pump is useful for increasing the rate at which cooling power is delivered to the vessel, and we present measurements of the power and efficiency of the apparatus.

S. Slutsky; Y. -R. Yen; H. Breuer; A. Dobi; C. Hall; T. Langford; D. S. Leonard; L. J. Kaufman; V. Strickland; N. Voskanian

2009-07-25

247

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope $\\alpha$-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

J. Renner; V. M. Gehman; A. Goldschmidt; H. S. Matis; T. Miller; Y. Nakajima; D. Nygren; C. A. B. Oliveira; D. Shuman; V. Álvarez; F. I. G. Borges; S. Cárcel; J. Castel; S. Cebrián; A. Cervera; C. A. N. Conde; T. Dafni; T. H. V. T. Dias; J. Díaz; R. Esteve; P. Evtoukhovitch; L. M. P. Fernandes; P. Ferrario; A. L. Ferreira; E. D. C. Freitas; A. Gil; H. Gómez; J. J. Gómez-Cadenas; D. González-Díaz; R. M. Gutiérrez; J. Hauptman; J. A. Hernando Morata; D. C. Herrera; F. J. Iguaz; I. G. Irastorza; M. A. Jinete; L. Labarga; A. Laing; I. Liubarsky; J. A. M. Lopes; D. Lorca; M. Losada; G. Luzón; A. Marí; J. Martín-Albo; A. Martínez; A. Moiseenko; F. Monrabal; M. Monserrate; C. M. B. Monteiro; F. J. Mora; L. M. Moutinho; J. Muñoz Vidal; H. Natal da Luz; G. Navarro; M. Nebot-Guinot; R. Palma; J. Pérez; J. L. Pérez Aparicio; L. Ripoll; A. Rodríguez; J. Rodríguez; F. P. Santos; J. M. F. dos Santos; L. Seguí; L. Serra; A. Simón; C. Sofka; M. Sorel; J. F. Toledo; A. Tomás; J. Torrent; Z. Tsamalaidze; J. F. C. A. Veloso; J. A. Villar; R. C. Webb; J. White; N. Yahlali

2014-09-09

248

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope $\\alpha$-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

Renner, J; Goldschmidt, A; Matis, H S; Miller, T; Nakajima, Y; Nygren, D; Oliveira, C A B; Shuman, D; Álvarez, V; Borges, F I G; Cárcel, S; Castel, J; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Díaz, J; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gil, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez, A; Moiseenko, A; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Palma, R; Pérez, J; Aparicio, J L Pérez; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Seguí, L; Serra, L; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R C; White, J; Yahlali, N

2014-01-01

249

The XENON dark matter experiment  

Microsoft Academic Search

The XENON experiment aims at the direct detection of dark matter in the form\\u000aof WIMPs (Weakly Interacting Massive Particles) via their elastic scattering\\u000aoff Xenon nuclei. With a fiducial mass of 1000 kg of liquid xenon, a\\u000asufficiently low threshold of ~16 keV recoil energy and an un-rejected\\u000abackground rate of 10 events per year, XENON would be sensitive

T. Shutt; E. Aprile; E. Baltz; K. Giboni; P. Majewski; M. Yamashita; K. Ni; U. Oberlack; J. Kwong; K. McDonald; M. Niemack; R. Gaitskell; P. Sorensen; L. Deviveiros; W. Craig

2005-01-01

250

Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage  

NASA Astrophysics Data System (ADS)

Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

251

Effect of moisture adsorption\\/desorption on external cylinder surfaces: influence on gravimetric preparation of reference gas mixtures  

Microsoft Academic Search

There are many error sources in the preparation of primary reference gas mixtures by the gravimetric method. One of the error\\u000a sources is the adsorption\\/desorption of moisture on the external gas cylinder surface. Variation of relative humidity in atomospheric\\u000a air around the cylinder during the preparation process may cause an error in the mass measurement of the gas cylinder. Effect

Nobuhiro Matsumoto; Takuro Watanabe; Kenji Kato

2005-01-01

252

The XENON100 Detector  

E-print Network

XENON100 is a liquid xenon (LXe) time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles (WIMPs). Operated in a low-background shield at the Gran Sasso underground laboratory in Italy, XENON100 has reached the unprecedented background level of $<$0.15 events/day/\\kevr in the energy range below 100 \\kevr in 30 kg of target mass, before electronic/nuclear recoil discrimination. It found no evidence for WIMPs during a dark matter run lasting for 100.9 live days in 2010, excluding with 90% confidence scalar WIMP-nucleon cross sections above 7x10$^{-45}$ cm$^{2}$ at a WIMP mass of 50 GeV/c$^{2}$. A new run started in March 2011, and more than 200 live days of WIMP-search data have been acquired. Results of this second run are expected to be released in summer 2012.

Scovell, P R

2012-01-01

253

The XENON100 Detector  

E-print Network

XENON100 is a liquid xenon (LXe) time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles (WIMPs). Operated in a low-background shield at the Gran Sasso underground laboratory in Italy, XENON100 has reached the unprecedented background level of $<$0.15 events/day/\\kevr in the energy range below 100 \\kevr in 30 kg of target mass, before electronic/nuclear recoil discrimination. It found no evidence for WIMPs during a dark matter run lasting for 100.9 live days in 2010, excluding with 90% confidence scalar WIMP-nucleon cross sections above 7x10$^{-45}$ cm$^{2}$ at a WIMP mass of 50 GeV/c$^{2}$. A new run started in March 2011, and more than 200 live days of WIMP-search data have been acquired. Results of this second run are expected to be released in summer 2012.

P. R. Scovell; XENON100 Collaboration

2012-06-28

254

Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization  

SciTech Connect

The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

Shneider, Mikhail N.; Miles, Richard B. [Applied Physics Group, MAE Department, Princeton University, Princeton, New Jersey 08544 (United States)

2012-08-15

255

ENHANCED SELECTIVE EXTRACTION OF HEXANE FROM HEXANE/SOYBEAN OIL MIXTURE USING BINARY GAS MIXTURES OF CARBON DIOXIDE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Both supercritical carbon dioxide (SC-CO2) and liquid carbon dioxide (L-CO2) have been shown to effectively separate the solvent hexane from the mixture of soybean oil (SBO) and hexane resulting from the hexane extraction of soybean flakes. However, there is a slight carry-over (ca. 2 wt%) of SBO c...

256

Analysis of an activated-carbon sorption compressor operating with gas mixtures  

NASA Astrophysics Data System (ADS)

Sorption compressors elevate the pressure of gases and can provide a more or less continuous mass flow. Unlike mechanical compressors, sorption compressors have no moving parts, and therefore do not emit vibrations and are highly reliable. There exist different sorption compressors for different operating conditions and various gases. However, there are no published reports of sorption compressors for mixed gases. Such compressors, among other applications, may drive mixed-refrigerant Joule-Thomson cryocoolers. The adsorption of mixed gases is usually investigated under steady conditions, mainly for storage and separation processes. However, the sorption process in a compressor goes through varying states and mass changes; therefore, it differs from the common mixed gases adsorption applications. In this research a numerical analysis for mixed gas sorption compressors is developed, based on pure gas adsorption characteristics and the ideal adsorbed solution theory. Two pure gas adsorption models are used for calculating the conditions of the adsorbed phase: Langmuir and Sips; and the Peng-Robinson equation of state is used to calculate the conditions of the vapor phase. Two mixtures are investigated; nitrogen-methane and nitrogen-ethane. Finally, the analysis is verified against experimental results. This research provides initiatory observation for mixed gases sorption compressor in which each component is differently adsorbed.

Tzabar, N.; Grossman, G.

2012-10-01

257

XENON100 Dark Matter Search: Scintillation Response of Liquid Xenon to Electronic Recoils  

NASA Astrophysics Data System (ADS)

Dark matter is one of the missing pieces necessary to complete the puzzle of the universe. Numerous astrophysical observations at all scales suggest that 23 % of the universe is made of nonluminous, cold, collisionless, nonbaryonic, yet undiscovered dark matter. Weakly Interacting Massive Particles (WIMPs) are the most well-motivated dark matter candidates and significant efforts have been made to search for WIMPs. The XENON100 dark matter experiment is currently the most sensitive experiment in the global race for the first direct detection of WIMP dark matter. XENON100 is a dual-phase (liquid-gas) time projection chamber containing a total of 161 kg of liquid xenon (LXe) with a 62kg WIMP target mass. It has been built with radiopure materials to achieve an ultra-low electromagnetic background and operated at the Laboratori Nazionali del Gran Sasso in Italy. WIMPs are expected to scatter off xenon nuclei in the target volume. Simultaneous measurement of ionization and scintillation produced by nuclear recoils allows for the detection of WIMPs in XENON100. Data from the XENON100 experiment have resulted in the most stringent limits on the spin-independent elastic WIMP-nucleon scattering cross sections for most of the significant WIMP masses. As the experimental precision increases, a better understanding of the scintillation and ionization response of LXe to low energy (< 10 keV) particles is crucial for the interpretation of data from LXe based WIMP searches. A setup has been built and operated at Columbia University to measure the scintillation response of LXe to both electronic and nuclear recoils down to energies of a few keV, in particular for the XENON100 experiment. In this thesis, I present the research carried out in the context of the XENON100 dark matter search experiment. For the theoretical foundation of the XENON100 experiment, the first two chapters are dedicated to the motivation for and detection medium choice of the XENON100 experiment, respectively. A general review about dark matter focusing on WIMPs and their direct detection with liquid noble gas detectors is presented in Chap. 1. LXe as an attractive WIMP detection medium is explained in Chap. 2. The XENON100 detector design, the detector, and its subsystems are detailed in Chap. 3. The calibration of the detector and the characterized detector response used for the discrimination of a WIMP-like signal against background are explained in Chap. 4. In an effort to understand the background, anomalous electronic recoils were studied extensively and are described in Chap. 5. In order to obtain a better understanding of the electronic recoil background of XENON100, including an estimation of the electronic recoil background contribution, as well as to interpret dark matter results such as annual modulation, measurement of the scintillation yield of low-energy electrons in LXe was performed in 2011, with the dedicated setup mentioned above. The results from this measurement are discussed in Chap. 6. Finally, the results for the latest science data from XENON100 to search for WIMPs, comprising 225 live-days taken over 13 months during 2011 and 2012 are explained in Chap. 7.

Lim, Kyungeun Elizabeth

258

The XENON100 Dark Matter Experiment  

E-print Network

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to measure Xe 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 Xe gas. The LXe target and veto are contained in a low-radioactivity stainless steel vessel, embedded in a passive radiation shield. The experiment is installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy and 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 \\sigma = 2x10^-45 c...

Aprile, E; 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; Undagoitia, T Marrodan; Mei, Y; Fernandez, A J Melgarejo; Ni, K; Oberlack, U; Orrigo, S E A; Pantic, E; Plante, G; Ribeiro, A C C; Santorelli, R; Santos, J M F dos; Schumann, M; Shagin, P; Teymourian, A; Tziaferi, E; Wang, H; Yamashita, M

2011-01-01

259

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

260

Supersonic Flow of Chemically Reacting Gas-Particle Mixtures. Volume 2: RAMP - A Computer Code for Analysis of Chemically Reacting Gas-Particle Flows  

NASA Technical Reports Server (NTRS)

A computer program written in conjunction with the numerical solution of the flow of chemically reacting gas-particle mixtures was documented. The solution to the set of governing equations was obtained by utilizing the method of characteristics. The equations cast in characteristic form were shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The characteristic directions for the gas-particle system are found to be the conventional gas Mach lines, the gas streamlines and the particle streamlines. The basic mesh construction for the flow solution is along streamlines and normals to the streamlines for axisymmetric or two-dimensional flow. The analysis gives detailed information of the supersonic flow and provides for a continuous solution of the nozzle and exhaust plume flow fields. Boundary conditions for the flow solution are either the nozzle wall or the exhaust plume boundary.

Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

1976-01-01

261

Requirements for Xenon International  

SciTech Connect

This document defines the requirements for the new Xenon International radioxenon system. The output of this project will be a Pacific Northwest National Laboratory (PNNL) developed prototype and a manufacturer-developed production prototype. The two prototypes are intended to be as close to matching as possible; this will be facilitated by overlapping development cycles and open communication between PNNL and the manufacturer.

Hayes, James C.; Ely, James H.; Haas, Derek A.; Harper, Warren W.; Heimbigner, Tom R.; Hubbard, Charles W.; Humble, Paul H.; Madison, Jill C.; Morris, Scott J.; Panisko, Mark E.; Ripplinger, Mike D.; Stewart, Timothy L.

2013-09-26

262

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

263

Multiproperty empirical isotropic interatomic potentials for CH4–inert gas mixtures  

PubMed Central

An approximate empirical isotropic interatomic potentials for CH4–inert gas mixtures are developed by simultaneously fitting the Exponential-Spline-Morse-Spline-van der Waals (ESMSV) potential form to viscosity, thermal conductivity, thermal diffusion factors, diffusion coefficient, interaction second pressure virial coefficient and scattering cross-section data. Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures for CH4–He and at T = 87 K for CH4–Ar are computed using theoretical values for overlap, octopole and hexadecapole mechanisms and interaction potential as input. Also, the quantum mechanical lineshapes of collision-induced light scattering (CILS) for the mixtures CH4–Ar and CH4–Xe at room temperature are calculated. The spectra of scattering consist essentially of an intense, purely translational component which includes scattering due to free pairs and bound dimers, and the other is due to the induced rotational scattering. These spectra have been interpreted by means of pair-polarizability terms, which arise from a long-range dipole-induced-dipole (DID) with small dispersion corrections and a short-range interaction mechanism involving higher-order dipole–quadrupole A and dipole–octopole E multipole polarizabilities. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when the models of potential, interaction-induced dipole and polarizability components are used.

El-Kader, M.S.A.

2012-01-01

264

Methodology for Predicting Flammable Gas Mixtures in Double Contained Receiver Tanks [SEC 1 THRU SEC 3  

SciTech Connect

This methodology document provides an estimate of the maximum concentrations of flammable gases (ammonia, hydrogen, and methane) which could exist in the vapor space of a double-contained receiver tank (DCRT) from the simultaneous saltwell pumping of one or more single-shell tanks (SSTs). This document expands Calculation Note 118 (Hedengren et a1 1997) and removes some of the conservatism from it, especially in vapor phase ammonia predictions. The methodologies of Calculation Note 118 (Hedengren et a1 1997) are essentially identical for predicting flammable gas mixtures in DCRTs from saltwell pumping for low DCRT ventilation rates, 1e, < 1 cfm. The hydrogen generation model has also been updated in the methodology of this document.

HEDENGREN, D.C.

2000-01-31

265

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

266

Development of proton-conducting membranes for separating hydrogen from gas mixtures  

SciTech Connect

Dense ceramic membranes made from mixed protonic/electronic conductors are permeable only to hydrogen, and in principle, provide a simple efficient means of separating hydrogen from gas mixtures. At a time when world demand for hydrogen is growing, such proton- conducting membranes have the potential to significantly alter the economics of hydrogen separation and purification processes and thus improve the economic viability of processes that utilize hydrogen, such as some refinery operations and direct and indirect coal liquefaction. This paper describes a recently initiated program to develop materials and fabrication processes to separate hydrogen with dense ceramic membranes in a non-Galvanic mode of operation (i.e., without electrodes or external power supply).

Dorris, S.E.; Balachandran

1996-06-01

267

Corona inception voltage in statorettes with various gas-solid dielectric systems  

NASA Technical Reports Server (NTRS)

Corona inception voltage was calculated and measured for three statorettes in several gases and gas mixtures at pressures from 50.8 to 1270 torr. In helium the corona inception voltage was lowest, and in air it was highest. In argon and mixtures of helium and xenon the corona inception voltage was between that of air and helium. Correlation between experimental and calculated data was good.

Bollenbacher, G.; Kempke, E. E., Jr.

1972-01-01

268

On Richtmyer-Meshkov instability in dilute gas-particle mixtures  

NASA Astrophysics Data System (ADS)

Richtmyer-Meshkov instability (RMI) in gas-particle mixtures is investigated both numerically and analytically. The linear amplitude growth rate for a RMI in a two-phase mixture is derived by using a dusty gas formulation for small Stokes number (St ?1.0), and it is shown that the problem can be characterized by mass loading and St. The model predictions are compared with numerical results under two conditions, i.e., a shock wave hitting (1) a perturbed species interface of air and SF6 surrounded by uniformly distributed particles, and (2) a perturbed shape particle cloud in uniform air. In the first case, the interaction between the instability of the species perturbation and the particles is investigated. The multiphase growth model accurately predicts the growth rates when St ?1.0, and the amplitude growth normalized by the two-phase RMI velocity shows good agreement with the single-phase RMI growth rate as well. It is also shown that the two-phase model results are in accordance with the growth rates obtained from the simulations even for cases corresponding to St ?10. However, for St ?10, particles do not follow the RMI motion, and the RMI growth rate agrees with the original Richtmyer's model [R. D. Richtmyer, "Taylor instability in shock acceleration of compressible fluids," Commun. Pure Appl. Math. 13, 297 (1960)]. Preferential concentration of particles are observed around the RMI roll-ups at late times when St is of order unity, whereas when St ?1.0, the particles respond rapidly to the flow, causing them to distribute within the roll-ups. In the second problem, the two-phase RMI growth model is extended to study whether a perturbed dusty gas front shows RMI-like growth due to the impact of a shock wave. When St ?1.0, good agreement with the multiphase model is again seen. Moreover, the normalized growth rates are very close to the single-phase RMI growth rates even at late times, which suggest that the two-phase growth model is applicable to this type of perturbed shape particle clouds as well. However, when St is close to unity or larger (St >1.0), the particles do not experience impulsive acceleration but rather a continuous one, which results in exponential growth rates as seen in a Rayleigh-Taylor instability.

Ukai, Satoshi; Balakrishnan, Kaushik; Menon, Suresh

2010-10-01

269

Calibrating the Xenon10 Detector with Activated Xenon  

Microsoft Academic Search

Xenon10 is a 15-kg liquid xenon (LXe) detector for the search of dark matter in the form of weakly interacting massive particles (WIMPs). The high scintillation yield of LXe and high light collection efficiency in Xenon10 allow the detection of low-energy nuclear recoils, e.g. from WIMPs elastic scattering, down to 10 keV. The energy calibration is usually performed by using

Kaixuan Ni

2007-01-01

270

Photoionization detector for the detection of xenon light  

Microsoft Academic Search

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.

1980-01-01

271

Automation of gas chromatography instruments. Part I. Automated peak identification in the chromatograms of standard test mixtures  

Microsoft Academic Search

The evaluation of the chromatogram recorded during the gas chromatographic analysis of a standard test mixture is of importance in the assessment of the performance of the underlying GC system. Automated evaluation is essential in the development of software that can be used in systems that can perform totally automated analysis. In this study, an algorithm for automated peak identification

Hai Du; Martin J. Stillman

1997-01-01

272

Breathing Gas Mixtures Different from Air: An Adaptation for Survival under the Ice of a Facultative Air-Breathing Fish  

Microsoft Academic Search

Gaseous respiration by central mudminnows (Umbra limi), particularly their use of bubbles composed of gas mixtures other than air, may have evolved as an adaptation to the oxygen-depleted, carbon dioxide--rich water of winterkill lakes. Under simulated winterkill conditions, mudminnows frequently engulfed gaseous bubbles. Use of bubbles was not related to varying methane or nitrogen content (0 to 80 percent) when

John J. Magnuson; John W. Keller; Annamarie L. Beckel; George W. Gallepp

1983-01-01

273

Theory and Calculation of the Condensation Growth of a Droplet in Pure Vapor and in a Vapor–Gas Mixture  

Microsoft Academic Search

Consideration is given to the theory of condensation as applied to the liquefaction of gases. Numerical calculations of the growth of a droplet using methane as an example revealed the decisive role of heat removal from its surface to the ambient medium in condensation from both a pure vapor and a vapor–gas mixture. It is shown that for very low

K. M. Aref'ev; Yu. G. Belostotskii; A. M. Koshelev

2001-01-01

274

Calibration of a Two Phase Liquid Xenon Time Projection Chamber with Kr-83m  

E-print Network

We report the testing of a charcoal based Kr-83m source for use in calibrating a low-background two-phase liquid xenon detector. Kr-83m atoms produced through the decay of Rb-83 are introduced into a xenon detector by flowing xenon gas past the Rb-83 source. 9.4 keV and 32.1 keV conversion electrons from decaying Kr-83m nuclei are detected through liquid xenon scintillation and ionization. Introduction of Kr-83m allows for quick, periodic calibration of low background noble liquid detectors at low energy.

Kastens, L W; Cahn, S B; Manzur, A; McKinsey, D N

2009-01-01

275

Xenon-Ion Drilling of Tungsten Films  

NASA Technical Reports Server (NTRS)

High-velocity xenon ions used to drill holes of controlled size and distribution through tungsten layer that sheaths surface of controlled-porosity dispenser cathode of traveling wave-tube electron emitter. Controlled-porosity dispenser cathode employs barium/calcium/ aluminum oxide mixture that migrates through pores in cathode surface, thus coating it and reducing its work function. Rapid, precise drilling technique applied to films of other metals and used in other applications where micron-scale holes required. Method requires only few hours, as opposed to tens of hours by prior methods.

Garner, C. E.

1986-01-01

276

FAST TRACK COMMUNICATION: Effects of reducing interferers in a binary gas mixture on NO2 gas adsorption using carbon nanotube networked films based chemiresistors  

NASA Astrophysics Data System (ADS)

Analysis of binary gas mixtures using chemiresistors based on carbon nanotubes (CNTs) networked films has been performed for chemical detection up to a sub-ppm level. The effects of individual interfering analytes of reducing H2S and NH3 gases on oxidizing NO2 gas adsorption in CNTs tangled films are considered. The CNTs are grown by plasma-enhanced chemical vapour deposition technology onto inexpensive alumina substrates, coated by cobalt nanosized catalyst. Charge transfer between adsorbed gas molecules and CNT networks, characterized by a semiconducting p-type electrical transport, occurs depending on opposite trend in the sensor response to the electron-donating interfering gases (H2S, NH3) and target electron-withdrawing NO2 gas causing a compensation of the charge transport, upon given working conditions. This compensated exchange of electrical charge affects the limit of detection of the targeted NO2 gas sensed in different real-world binary gas mixtures of reducing interferers of H2S and NH3. In addition, the functionalization of the CNT films with Au nanoclusters enhanced the sensitivity of the chemiresistor and tuned the compensation of electrical charge crossover in the selected binary oxido-reducing mixtures.

Penza, M.; Rossi, R.; Alvisi, M.; Signore, M. A.; Serra, E.

2009-04-01

277

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

278

Supersonic flow of chemically reacting gas-particle mixtures. Volume 1: A theoretical analysis and development of the numerical solution  

NASA Technical Reports Server (NTRS)

A numerical solution for chemically reacting supersonic gas-particle flows in rocket nozzles and exhaust plumes was described. The gas-particle flow solution is fully coupled in that the effects of particle drag and heat transfer between the gas and particle phases are treated. Gas and particles exchange momentum via the drag exerted on the gas by the particles. Energy is exchanged between the phases via heat transfer (convection and/or radiation). Thermochemistry calculations (chemical equilibrium, frozen or chemical kinetics) were shown to be uncoupled from the flow solution and, as such, can be solved separately. The solution to the set of governing equations is obtained by utilizing the method of characteristics. The equations cast in characteristic form are shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The particle distribution is represented in the numerical solution by a finite distribution of particle sizes.

Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

1976-01-01

279

Precise Attitude Control of All-Electric GEO Spacecraft using Xenon Microthrusters  

E-print Network

Precise Attitude Control of All-Electric GEO Spacecraft using Xenon Microthrusters IEPC-2013- form. The attitude control system is based on cold gas and electrothermal Xenon mi- crothrusters scientific organizations have suffered from budget limitations. As a consequence, commercial platforms

Giannitrapani, Antonello

280

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...

281

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

282

A logarithmic multi-parameter model using gas sensor main and cross sensitivities to estimate gas concentrations in a gas mixture for SnO 2 gas sensors  

Microsoft Academic Search

In a metal-oxide semiconductor gas sensor, the sensitivity of the metal-oxide resistance to concentrations of reducing gases in the surrounding atmosphere is known to be related to adsorption and desorption of gas on the redox reactions between the gas and oxygen. Changes in the electric conductance due to these reactions were measured for tin dioxide semiconductor gas sensors. In this

A. Chaiyboun; R. Traute; T. Haas; O. Kiesewetter; T. Doll

2007-01-01

283

Experimental Investigation on High-pressure, High-temperature Viscosity of Gas Mixtures  

E-print Network

was used to measure the viscosity of mixtures of nitrogen and methane, and mixtures of CO2 and methane at a pressure range of 5,000 to 25,000 psi, and a temperature range of 100 to 360 degrees F. The viscosity of mixtures of nitrogen and methane...

Davani, Ehsan

2012-02-14

284

Effect of two gas mixtures on growth of the domestic fowl embryo from days 14 through 17 of incubation.  

PubMed

Eggs weighing 62.5 +/- 0.5 gm when fresh were incubated in air in a forced-draft incubator for 13 days during which time their shell conductance to water vapor (GH2O) was determined. Eggs whose shells represented the entire range of GH2O values present in the population were then incubated for a further 4 days in either air or an experimental gas mixture. Embryo dry weights were determined after a total of 408 hr of incubation to assess the affect of the experimental gas mixture on embryonic development. Embryo growth was found to be stimulated for all eggshell conductances by 4 days incubation in a 50% oxygen/50% nitrogen mixture. This suggests that the decrease in oxygen within the egg that occurs during development normally limits embryonic growth. Growth of the embryo was unaffected by 4 days incubation in a mixture of 17% oxygen/83% helium. This mixture reduced the carbon dioxide tension in the airspace but did not affect the oxygen tension relative to eggs incubated in air. It is suggested, therefore, that the carbon dioxide that builds up within eggs during incubation does not limit embryo growth. PMID:3598503

Tullett, S G; Burton, F G

1987-01-01

285

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. PMID:22146153

2011-01-01

286

WIMP Searches with Liquid Xenon: the XENON10 Experiment  

Microsoft Academic Search

The XENON experiment searches for Weakly Interacting Massive Particles (WIMPs) with liquid xenon (LXe) as the active target. The detector is a 3-D position sensitive Time Projection Cham- ber optimized to simultaneously measure the ionization and scintillation produced by a recoil event down to energies of 16 keV. The distinct ratio of the two signals for nuclear recoils arising from

Laura Baudis

2005-01-01

287

The XENON dark matter search: status of XENON10  

NASA Astrophysics Data System (ADS)

The XENON experiment searches for dark matter particles called WIMPs using liquid xenon (LXe) as the active target. The detector is a 3D position sensitive Time Projection Chamber optimized to simultaneously measure the ionization and scintillation produced by a recoil event of energy as low as 16 keV. The distinct ratio of the two signals for nuclear recoils arising from WIMPs and neutrons and for electron recoils from the dominant gamma-ray background determines its event-by-event discrimination. 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. A phased program will test a 10 kg detector (XENON10) followed by a 100 kg (XENON100) one as unit module for the XENON1T scale experiment. We review the progress of the XENON R & D phase before presenting the status of XENON10. The experiment will be based at the Gran Sasso Underground Laboratory and is expected to start data taking in early 2006.

Aprile, E.; Giboni, K. L.; Kamat, S.; Ni, K.; Singh, B. K.; Yamashita, M.; Gaitskell, R. J.; Sorensen, P.; de Viveiros, L.; Gomez, R.; Oberlack, U.; Shagin, P.; Bolozdynya, A.; Dahl, E.; Kwong, J.; Shutt, T.; Angle, J.; Baudis, L.; Manalaysay, A.; Orboeck, J.; Hasty, R.; Manzur, A.; McKinsey, D.; Bernstein, A.; Madden, N.; Winant, C.; Arneodo, F.; Ferella, A.; Matias Lopes, J. A.; Santos, J.

2006-05-01

288

The XENON dark matter search: status of XENON10  

Microsoft Academic Search

The XENON experiment searches for dark matter particles called WIMPs using liquid xenon (LXe) as the active target. The detector is a 3D position sensitive Time Projection Chamber optimized to simultaneously measure the ionization and scintillation produced by a recoil event of energy as low as 16 keV. The distinct ratio of the two signals for nuclear recoils arising from

E. Aprile; K. L. Giboni; S. Kamat; K. Ni; B. K. Singh; M. Yamashita; R. J. Gaitskell; P. Sorensen; L. de Viveiros; R. Gomez; U. Oberlack; P. Shagin; A. Bolozdynya; E. Dahl; J. Kwong; T. Shutt; J. Angle; L. Baudis; A. Manalaysay; J. Orboeck; R. Hasty; A. Manzur; D. McKinsey; A. Bernstein; N. Madden; C. Winant; F. Arneodo; A. Ferella; J. A. Matias Lopes; J. Santos

2006-01-01

289

Dynamic Characteristics of SF6-N2-CO2 Gas Mixtures in DC Discharge Process  

NASA Astrophysics Data System (ADS)

Dynamic characteristics of discharge particles are described within the framework of a two-dimensional photoionization-hydrodynamic numerical model for the discharge process of SF6-N2-CO2 gas mixtures at atmospheric pressure, under a uniform DC applied field. The finite difference—flux corrected transport (FD-FCT) algorithm is used in the numerical implementation for improving the accuracy and efficiency. Then the tempo-spatial distributions of the gap—space electric field and electron velocity are calculated from the microscopic mechanism, and the dynamic behaviors of charged particles are obtained in detail. Meanwhile, the tempo—spatial critical point of the avalanche-to-streamer in this model is discovered, and several microscopic parameters are also investigated. The results showed that the entire gap discharge process can be divided into two phases of avalanche and streamer according to Raether-Meek criterion; the electron density within the discharge channel is lower compared to that of positive and negative ions; space charge effect is a dominant factor for the distortion of spatial electric field, making the discharge channel expand toward both electrodes faster; photoionization provides seed electrons for a secondary electron avalanche, promoting the formation and development speed of the streamer.

Zheng, Dianchun; Wang, Jia; Chen, Chuntian; Zhao, Dawei; Zhang, Chunxi; Yang, Jiaxiang

2014-09-01

290

Effect of focal size on the laser ignition of compressed natural gas-air mixture  

NASA Astrophysics Data System (ADS)

Laser ignition of compressed natural gas-air mixtures was investigated in a constant volume combustion chamber (CVCC) as well as in a single cylinder engine. Laser ignition has several potential advantages over conventional spark ignition system. Laser ignition relies on the fact that optical breakdown (plasma generation) in gases occurs at high intensities of ?1011 W/cm2. Such high intensities can be achieved by focusing a pulsed laser beam to small focal sizes. The focal spot size depends on several parameters such as laser wavelength, beam diameter at the converging lens, beam quality and focal length. In this investigation, the focal length of the converging lens and the beam quality were varied and the corresponding effects on minimum ignition energy as well as pressure rise were recorded. The flame kernel was visualized and correlated with the rate of pressure rise inside the combustion chamber. This investigation will be helpful in the optimization of laser and optics parameters in laser ignition. It was found that beam quality factor and focal length of focusing lens have a strong impact on the minimum ignition energy required for combustion. Combustion duration depends on the energy density at the focal spot and size of the flame kernel.

Srivastava, Dhananjay Kumar; Wintner, Ernst; Agarwal, Avinash Kumar

2014-07-01

291

Nitridation behavior of sapphire using a carbon-saturated N2-CO gas mixture  

NASA Astrophysics Data System (ADS)

The authors previously developed a sapphire nitridation method using carbon-saturated N2-CO gas mixture to form a high-quality AlN film for III-nitride-based optoelectronic devices. In this study, the nitridation behavior of (0001) (c) plane and (112¯0) (a) plane sapphire was studied to elucidate and optimize the process at temperatures of 1823 and 1873 K. The AlN film thickness, surface morphology, crystal quality, and interfacial phenomena were investigated as functions of nitridation time and temperature. Fundamentally, the AlN film grows as a result of the diffusion process that occurs in the AlN film. The voids found at the AlN/sapphire interface indicate that the Al2O3 dissociates into Al3+ and O2- ions, and that the ions diffuse in the AlN film. However, the growth rate of AlN film does not obey the simple diffusion model. The AlN film thickness has a maximum and decreases slightly with time, which indicates that the thermal decomposition of AlN film must be considered when comprehensively describing the nitridation process.

Fukuyama, Hiroyuki; Nakamura, Katsuhito; Aikawa, Toshiaki; Kobatake, Hidekazu; Hakomori, Akira; Takada, Kazuya; Hiraga, Kenji

2010-02-01

292

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

293

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

294

Fusion reactions in a plasma focus operated with He3-D-2 and He4-D-2 gas mixtures  

Microsoft Academic Search

A 3 kJ plasma focus (PF) device was operated with two different gas\\u000a mixtures: He-3-D-2 and He-4-D-2, both having He\\/D atomic ratios of 1 :\\u000a 1. For the He-3-D-2 mixture, the fusion reactions D(He-3,p)He-4 and\\u000a D(d,p)H-3 were measured simultaneously using CR-39 nuclear track\\u000a detectors located inside a pinhole camera positioned on the forward PF\\u000a axis. A double-layer arrangement of two

S. V. Springham; T. H. Sim; P. Lee; A. Patran; R. S. Rawat; P. M. E. Shutler; T. L. Tan; S. Lee

2006-01-01

295

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid, forces it to evaporate, and thus cools it down. We show that this temperature difference can be used for an efficient heat exchange process. We investigate the use of a commercial parallel plate heat exchanger with a small liquid xenon detector. Although we expected to be limited by the available cooling power to flow rates of about 2 SLPM, rates in excess of 12 SLPM can easily be sustained, limited only by the pump speed and the impedance of the flow loop. The heat exchanger operates with an efficiency of (96.8 +/- 0.5)%. This opens the possibility for fast xenon gas recirculation in large-scale experiments, while minimizing thermal losses.

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-03-04

296

The XENON Dark Matter Experiment  

Microsoft Academic Search

The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to measure Xe 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.

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

2011-01-01

297

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

298

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

299

Shear Thinning in Xenon  

NASA Technical Reports Server (NTRS)

We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

2009-01-01

300

Carcase and meat quality in ducks killed with either gas mixtures or an electric current under commercial processing conditions.  

PubMed

1. The feasibility of killing 7-week old Peking ducks with gas mixtures and their effects on carcase and meat quality were evaluated and compared with killing in electrical waterbath under commercial conditions. 2. The prevalence of carcase appearance defects and broken bones in the carcases and haemorrhaging, pH, colour, cooking loss and texture of breast muscles were determined. 3. Ducks can be killed within 3 min by exposure to either 90% argon in air or a mixture of 30% carbon dioxide and 60% argon in air. 4. Gas or controlled-atmosphere killing of ducks, whilst they are still in their transport containers, would eliminate some of the welfare concerns associated with the conventional electrical waterbath stunning systems, without adversely affecting carcase and meat quality. PMID:9693822

Raj, A B; Richardson, R I; Wilkins, L J; Wotton, S B

1998-07-01

301

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

302

Dry etching of CdTe/GaAs epilayers using CH{sub 4}H{sub 2} gas mixtures  

SciTech Connect

A CH{sub 4}/H{sub 2} gas mixture has been used for the dry etching of (100) and (111) oriented CdTe epilayers in a barrel reactor. The effects of various process parameters on etch rate and surface morphology were studied with special attention paid to the gas composition and the total chamber pressure as well as the crystallographic orientation of the sample. Clear evidence is found for both isotropic and preferential etching along crystalolographic planes depending on the set of etch parameters used. 14 refs., 7 figs.

Neswal, M.; Gresslehner, K.H.; Lischka, K. [Johannes Kepler Universitaet Linz (Austria)] [and others] [Johannes Kepler Universitaet Linz (Austria); and others

1993-05-01

303

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

304

Rayleigh-Benard convection in binary-gas mixtures: Thermophysical properties and the onset of convection  

E-print Network

, and thermal-conductivity measurements. All six mixtures have positive separa- tion ratios . The Lewis number L the ratio of the mass to the thermal diffusivity is of O(1), in contrast to liquid mixtures where L O(10 2 the effective thermal conductivity and from the contrast of shadowgraph images as a function of T. The results

Ahlers, Guenter

305

Rayleigh-Brillouin Light Scattering from Noble Gas Mixtures. 1. The Landau-Placzek Ratio  

Microsoft Academic Search

We present the Rayleigh-Brillouin light scattering data for He + Xe mixtures of various compositions and pressures between 2 and 10 MPa. We compare our experimental data to calculations for a mixture that behaves according to the van der Waals equation of state. Our analysis shows that the contribution of concentration fluctuations to the Landau-Placzek ratio is very important. Furthermore,

Arjen Bot; H. M. Schaink; R. P. C. Schram; G. H. Wegdam

1991-01-01

306

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

307

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

308

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

309

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid...

Giboni, K L; Choi, B; Haruyama, T; Lang, R F; Lim, K E; Melgarejo, A J; Plante, G; 10.1088/1748-0221/6/03/P03002

2011-01-01

310

Separating Mixtures  

NSDL National Science Digital Library

Students learn how to classify materials as mixtures, elements or compounds and identify the properties of each type. The concept of separation of mixtures is also introduced since nearly every element or compound is found naturally in an impure state such as a mixture of two or more substances, and it is common that chemical engineers use separation techniques to separate mixtures into their individual components. For example, the separation of crude oil into purified hydrocarbons such as natural gas, gasoline, diesel, jet fuel and/or lubricants.

2014-09-18

311

Gas emissions and engine behavior when gasoline-alcohol mixtures are used.  

PubMed

This paper deals with the use of gasoline-methanol and gasoline-ethanol mixtures in a small four-stroke engine of internal combustion that is used for the movement of a small alternative generator. It was observed that CO and HC emissions decrease compared to gasoline when the percentage of methanol, ethanol in the fuel was increased, under different load conditions (without load conditions and under full electrical load conditions). The use of gasoline-methanol mixtures showed a higher decrease of emissions. When the mixtures of gasoline-70%methanol and gasoline-90%ethanol and 100%ethanol for which the engine malfunctioned, the rpm of the engine were not constant and the emissions were increased. It is also important that (with the existing regulation of the fuel/air ratio that refers to gasoline) the engine functioned for the case of gasoline-methanol mixtures up to a concentration of -70%methanol mixture, while for the case of gasoline-ethanol mixtures until the use of 100%ethanol. Furthermore, during the use of the mixtures of gasoline-methanol and gasoline-ethanol there was a small increase of fuel consumption when the percentage of the methanol or ethanol in the fuel was increased. PMID:14599140

Arapatsakos, C I; Karkanis, A N; Sparis, P D

2003-09-01

312

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

313

Electron-beam sustained discharge in oxygen gas mixtures: singlet delta oxygen production for oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Electric properties and spectroscopy of an e-beam sustained discharge (EBSD) in oxygen and oxygen gas mixtures at gas pressure up to 100 Torr were experimentally studied. The pulsed discharge in pure oxygen and its mixtures with noble gases was shown to be very unstable and characterized by low input energy. When adding small amount of carbon monoxide or hydrogen, the electric stability of the discharge increases, specific input energy (SIE) per molecular component being more than order of magnitude higher and coming up to 6.5 kJ/(l atm) for gas mixture O2:Ar:CO = 1:1:0.1. The results of experiments on spectroscopy of the singlet delta oxygen O2(a1?g)(SDO) and O2(b1?g+) states in the EBSD are presented. The calibration of the optical scheme for measuring the SDO absolute concentration and yield using the detection of luminescence of the SDO going from a chemical SDO generator was done. The preliminary measurement of the SDO yield demonstrated that it was ~3% for the SIE of ~1 kJ/(l atm), which is close to the results of theoretical calculations for such a SIE. Theoretical calculations demonstrated that for the SIE of 6.5 kJ/(l atm) the SDO yield may reach ~20% exceeding its threshold value needed for oxygen-iodine laser operation at room temperature, although a part of the energy loaded into the EBSD goes into the vibrational energy of the molecular admixture, (which was experimentally demonstrated by launching a CO laser operating on an oxygen-rich mixture O2:Ar:CO = 1:1:0.1 and measuring its small-signal gain).

Frolov, Mikhail P.; Hager, Gordon D.; Ionin, Andrei A.; Klimachev, Yurii M.; Kochetov, Igor V.; Kotkov, Andrei A.; McIver, John K.; Napartovich, Anatolii P.; Podmar'kov, Yurii P.; Seleznev, Leonid V.; Sinitsyn, Dmitrii V.; Vagin, Nikolai P.; Yuryshev, Nikolay N.

2004-09-01

314

Standardization of xenon-127 and measurement of photon emission intensities.  

PubMed

Xenon-127 was standardized by internal gas counting using three proportional counters in a differential arrangement to eliminate edge effects. The detection efficiency of the proportional counters was calculated by considering the cascade of events following the electron capture and associated gamma transitions. Activity per unit volume was measured with 0.7% relative standard uncertainty. Gamma-ray spectrometry was performed and absolute photon emission intensities were derived. This study shows that (127)Xe could be a surrogate for (133)Xe for the calibration of remote radio-xenon monitoring stations. PMID:24360861

Rodrigues, M; Lépy, M-C; Cassette, P; Mougeot, X; Bé, M M

2014-05-01

315

Carcase and meat quality in broilers either killed with a gas mixture or stunned with an electric current under commercial processing conditions  

Microsoft Academic Search

1. Carcase and meat quality were evaluated under commercial conditions in 400 broilers either killed with a mixture of 30% carbon dioxide and 60% argon in air or stunned with a 50 Hz AC with clipped sine wave.2. Compared with electrical stunning, killing broilers with the gas mixture eliminated or substantially reduced the prevalence of carcase and meat quality defects.3.

A. B. M. Raj; L. J. Wilkins; R. I. Richardson; S. P. Johnson; S. B. Wotton

1997-01-01

316

A photochemical answer to the 'xenon paradox'  

NASA Astrophysics Data System (ADS)

Xenon is depleted by one order of magnitude relative to other volatile elements when normalized to the chondritic composition. Furthermore, atmospheric xenon is far more enriched in the heavy isotopes relatively to chondritic and solar compositions (3-4%.amu-1) than atmospheric krypton (< 1%.amu-1). This discrepancy, known as the 'xenon paradox', has led to sophisticated models of atmospheric evolution coupled with mantle geodynamics (Pepin, 1991; Tolstikhin and Marty, 1998) and cometary contributions (Dauphas, 2003; Owen et al., 1992) that could explain terrestrial noble gas patterns under ad hoc conditions during the building stages of the Earth, no more than ~200 Ma following the beginning of solar system formation. Yet, xenon having an isotopic composition intermediate between the atmospheric and the chondritic ones has been recently documented in Archean (?3 Ga-old) sedimentary rocks (Pujol et al., 2011), suggesting that isotopic fractionation of Xe occurred over a much longer period of time than previously thought, during the Hadean and the Archean eons. In that case, assuming a Rayleigh type isotope evolution for atmospheric Xe requires an enrichment fractionation factor of 1.3% in heavy isotopes for Xe remaining in the atmosphere. This is clearly within the range of values observed in laboratory experiments aimed at trapping and fractionating Xe isotopes in solids, which is only effective upon ionization (Marrocchi et al., 2011; Kuga et al., 2012). We report here a possibility for explaining the 'xenon paradox' through interaction of the Hadean/Archean atmosphere with EUV light from the young Sun. By using a new photochemical model, we have found out that atmospheric Xe depletion and enrichment in heavy Xe isotopes could be achieved by EUV photoionization deep enough in the atmosphere to allow the preferential implantation of the heavier Xe isotopes in organic aerosols, the formation of which is itself triggered by UV photochemistry. Most of the ionized Xe would have escaped from the atmosphere into space by hydrodynamic escape (Zahnle, 2011). We have established that this mechanism specifically affected Xe and was particularly effective during the Hadean/Archean times, since the irradiation flux was expected to be orders of magnitude higher than today (Ribas et al., 2010). Dauphas (2003), Icarus 165, 326-339. Kuga et al. (2012), #2347 Goldschmidt 2012 Marrocchi et al. (2011), GCA 75, 6255-6266. Owen et al. (1992), Nature 358, 43-46. Pepin (1991), Icarus 92, 1-79. Pujol et al. (2011), Earth Planet. Sci. Lett. 308, 298-306. Ribas et al. (2010), Astrophys. J. 714, 384-395. Srinivasan, (1976), Earth Planet. Sci. Lett. 31, 129-141. Tolstikhin and Marty (1998), Chem. Geol. 147, 27-52. Zahnle (2011), #2241 Goldschmidt 2011

Hébrard; Marty, B.

2012-12-01

317

High-pressure xenon detector development at Constellation Technology Corporation  

NASA Astrophysics Data System (ADS)

Xenon-filled ionization detectors, due to their high atomic number fill gas (Z=54), moderate densities (~0.3 g/cm 3-0.5 g/cm 3) and good energy resolution (2%-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and Germanium detectors. Until recently, difficulties with obtaining sufficient Xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990's, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Here we will discuss our development of a mobile, large area, spectroscopic array.

Austin, Robert A.; Bastian, Lloyd F.

2006-08-01

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

Calibration of the XENON100 Time Projection Chamber  

NASA Astrophysics Data System (ADS)

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. Following the successful performance of the XENON10, we have designed and built a new detector with a total Xe mass of 170 kg, and with 100 times less background. The XENON100 detector is currently undergoing commissioning at the Gran Sasso Underground Laboratory. The calibration of the detector with gamma sources and with low energy neutrons is essential to determine the response to electron and nuclear recoils, and their discrimination based on the ratio of ionization to scintillation, as well as on event positioning and scattering-multiplicity within the active liquid volume. External gamma sources used for the XENON100 calibration include Cs-137, Co-57 and Co-60. An external Am-Be source is used for irradiation by neutrons. Additionally, we have been testing mixing Kr-83m (tau=12.6 hr, 18 and 32 keV electrons and 13 keV x-rays) into the LXe target, as internal source of low energy electron recoils. We discuss how different detector performance parameters such as light yield and electron lifetime can be inferred from these calibrations and show how the spatial dependence of some other parameters (light collection efficiency for example) can be obtained. We also present comparisons of results from calibrations with Monte Carlo simulations.

Lim, Kyungeun

2009-05-01

320

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

321

Xenon-related analgesia: a new target for pain treatment.  

PubMed

The noble gas xenon has been known for >50 years in the field of anesthesia with an emerging series of favorable features; several clinical and preclinical studies performed over the last years reveal a renewed interest because they substantially agree on attributing relevant analgesic properties to xenon. The main mechanism of action is the inhibition of N-methyl-D-aspartate receptors of glutamate; it involves the blocking of painful stimuli transmissions from peripheral tissues to the brain and it also avoids the development of pain hypersensitivity. Therefore, this mechanism is responsible for the inhibition of pain transmission at spinal and supraspinal levels, as well as the cortical level. In all these levels of pain pathways, as the development of hyperalgesia is possible, xenon efficacy can also be based on the blocking of these processes. Several forms of pain share such mechanisms in their maintenance, and xenon can be successfully used at low dosages, which have no effects on vital parameters. The literature shows that analgesic features could also emerge outside the field of anesthesia; thus, this could permit xenon to have a larger usage according to local availability. PMID:23328329

Giacalone, Marilù; Abramo, Antonio; Giunta, Francesco; Forfori, Francesco

2013-07-01

322

High-pressure autoignition of natural gas/air mixtures and the problem of engine knock. Topical report  

SciTech Connect

Although increases in compression ratio can improve the efficiency of most internal combustion engines, including those fueled by natural gas, the onset of engine knock provides an upper limit to the compression ratio at which the engine can be operated. The chemical factors involved in autoignition and knock in these engines are reviewed in the report and those operating parameters which have the greatest influence on the knocking tendency are identified and quantified. The fuel composition (the relative proportions of methane, ethane, and higher hydrocarbons) and the gas-mixture temperature are found to be most important in determining the rate of autoignition, while the equivalence ratio, initial pressure, amount of exhaust gas recirculation, and amount of antiknock additive are of somewhat lesser importance.

Westbrook, C.K.; Pitz, W.J.

1987-09-01

323

Observation and applications of single-electron charge signals in the XENON100 experiment  

NASA Astrophysics Data System (ADS)

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter weakly interacting massive particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

Aprile, E.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Balan, C.; Baudis, L.; Bauermeister, B.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Cardoso, J. M. R.; Chen, W.-T.; Choi, B.; Colijn, A. P.; Contreras, H.; Cussonneau, J. P.; Decowski, M. P.; Duchovni, E.; Fattori, S.; Ferella, A. D.; Fulgione, W.; Gao, F.; Garbini, M.; Ghag, C.; Giboni, K.-L.; Goetzke, L. W.; Grignon, C.; Gross, E.; Hampel, W.; Itay, R.; Kaether, F.; Kessler, G.; Kish, A.; Lamblin, J.; Landsman, H.; Lang, R. F.; Le Calloch, M.; Levy, C.; Lim, K. E.; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Lung, K.; Marrodán Undagoitia, T.; Massoli, F. V.; Melgarejo Fernandez, A. J.; Meng, Y.; Messina, M.; Molinario, A.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Persiani, R.; Piastra, F.; Plante, G.; Priel, N.; Rizzo, A.; Rosendahl, S.; dos Santos, J. M. F.; Sartorelli, G.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.

2014-03-01

324

Observation and applications of single-electron charge signals in the XENON100 experiment  

E-print Network

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

E. Aprile; M. Alfonsi; K. Arisaka; F. Arneodo; C. Balan; L. Baudis; B. Bauermeister; A. Behrens; P. Beltrame; K. Bokeloh; A. Brown; E. Brown; S. Bruenner; G. Bruno; R. Budnik; J. M. R. Cardoso; W. -T. Chen; B. Choi; A. P. Colijn; H. Contreras; J. P. Cussonneau; M. P. Decowski; E. Duchovni; S. Fattori; A. D. Ferella; W. Fulgione; F. Gao; M. Garbini; C. Ghag; K. -L. Giboni; L. W. Goetzke; C. Grignon; E. Gross; W. Hampel; R. Itay; F. Kaether; G. Kessler; A. Kish; J. Lamblin; H. Landsman; R. F. Lang; M. Le Calloch; C. Levy; K. E. Lim; Q. Lin; S. Lindemann; M. Lindner; J. A. M. Lopes; K. Lung; T. Marrodan Undagoitia; F. V. Massoli; A. J. Melgarejo Fernandez; Y. Meng; M. Messina; A. Molinario; J. Naganoma; K. Ni; U. Oberlack; S. E. A. Orrigo; E. Pantic; R. Persiani; F. Piastra; G. Plante; N. Priel; A. Rizzo; S. Rosendahl; J. M. F. dos Santos; G. Sartorelli; J. Schreiner; M. Schumann; L. Scotto Lavina; M. Selvi; P. Shagin; H. Simgen; A. Teymourian; D. Thers; O. Vitells; H. Wang; M. Weber; C. Weinheimer

2013-11-05

325

Observation and applications of single-electron charge signals in the XENON100 experiment  

E-print Network

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

Aprile, E; Arisaka, K; Arneodo, F; Balan, C; Baudis, L; Bauermeister, B; Behrens, A; Beltrame, P; Bokeloh, K; Brown, A; Brown, E; Bruenner, S; Bruno, G; Budnik, R; Cardoso, J M R; Chen, W -T; Choi, B; Colijn, A P; Contreras, H; Cussonneau, J P; Decowski, M P; Duchovni, E; Fattori, S; Ferella, A D; Fulgione, W; Gao, F; Garbini, M; Ghag, C; Giboni, K -L; Goetzke, L W; Grignon, C; Gross, E; Hampel, W; Itay, R; Kaether, F; Kessler, G; Kish, A; Lamblin, J; Landsman, H; Lang, R F; Calloch, M Le; Levy, C; Lim, K E; Lin, Q; Lindemann, S; Lindner, M; Lopes, J A M; Lung, K; Undagoitia, T Marrodan; Massoli, F V; Fernandez, A J Melgarejo; Meng, Y; Messina, M; Molinario, A; Naganoma, J; Ni, K; Oberlack, U; Orrigo, S E A; Pantic, E; Persiani, R; Piastra, F; Plante, G; Priel, N; Rizzo, A; Rosendahl, S; Santos, J M F dos; Sartorelli, G; Schreiner, J; Schumann, M; Lavina, L Scotto; Selvi, M; Shagin, P; Simgen, H; Teymourian, A; Thers, D; Vitells, O; Wang, H; Weber, M; Weinheimer, C

2014-01-01

326

Effect of hydrogen ratio on plasma parameters of N{sub 2}-H{sub 2} gas mixture glow discharge  

SciTech Connect

A dc plane glow discharge in a nitrogen-hydrogen (N{sub 2}-H{sub 2}) gas mixture has been operated at discharge currents of 10 and 20 mA. The electron energy distribution function (EEDF) at different hydrogen concentrations is measured. A Maxwellian EEDF is found in the positive column region, while in both cathode fall and negative glow regions, a non-Maxwellian one is observed. Langmuir electric probes are used at different axial positions, gas pressures, and hydrogen concentrations to measure the electron temperature and plasma density. The electron temperature is found to increase with increasing H{sub 2} concentration and decrease with increasing both the axial distance from the cathode and the mixture pressure. At first, with increasing distance from the cathode, the ion density decreases, while the electron density increases; then, as the anode is further approached, they remain nearly constant. At different H{sub 2} concentrations, the electron and ion densities decrease with increasing the mixture pressure. Both the electron and ion densities slightly decrease with increasing H{sub 2} concentration.

El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A. [Benha University, Physics Department, Faculty of Science (Egypt); Rashed, U. M. [Alazhar University, Physics Department, Faculty of Science (Egypt); Hassouba, M. A. [Benha University, Physics Department, Faculty of Science (Egypt)

2012-05-15

327

Effects of NH3 and N2 additions to hot filament activated CH4/H2 gas mixtures  

NASA Astrophysics Data System (ADS)

Resonance enhanced multiphoton ionization and cavity ring down spectroscopies have been used to provide spatially resolved measurements of relative H atom and CH3 radical number densities, and NH column densities, in a hot filament (HF) reactor designed for diamond chemical vapor deposition and here operating with a 1% CH4/n/H2 gas mixture—where n represents defined additions of N2 or NH3. Three-dimensional modeling of the H/C/N chemistry prevailing in such HF activated gas mixtures allows the relative number density measurements to be placed on an absolute scale. Experiment and theory both indicate that N2 is largely unreactive under the prevailing experimental conditions, but NH3 additions are shown to have a major effect on the gas phase chemistry and composition. Specifically, NH3 additions introduce an additional series of "H-shift" reactions of the form NHx+H?NHx-1+H2 which result in the formation of N atoms with calculated steady state number densities >1013 cm-3 in the case of 1% NH3 additions in the hotter regions of the reactor. These react, irreversibly, with C1 hydrocarbon species forming HCN products, thereby reducing the concentration of free hydrocarbon species (notably CH3) available to participate in diamond growth. The deduced reduction in CH3 number density due to competing gas phase chemistry is shown to be compounded by NH3 induced modifications to the hot filament surface, which reduce its efficiency as a catalyst for H2 dissociation, thus lowering the steady state gas phase H atom concentrations and the extent and efficiency of all subsequent gas phase transformations.

Smith, James A.; Wills, Jonathan B.; Moores, Helen S.; Orr-Ewing, Andrew J.; Ashfold, Michael N. R.; Mankelevich, Yuri A.; Suetin, Nikolay V.

2002-07-01

328

Influence of inert gas additive to xenon on the efficiency of luminescence output of Xe 2 * molecules with electron beam excitation  

Microsoft Academic Search

surements were conducted corresponded to the second continuum of Xe2( I timewise resolution of the recording system (a type ELU-F7 photomultiplier with a window coated with yellow lumogen, and a type Ci-ll oscilloscope) was ~4 nsec. The vacuum UV radiation energy was determined by graphical integration of the oscillogram pulses. Figure 1 shows typical oscillograms of radiation pulses from mixtures

Yu. I. Dymshits; V. A. Korobitsyn

1986-01-01

329

Recognizing indoor formaldehyde in binary gas mixtures with a micro gas sensor array and a neural network  

Microsoft Academic Search

Low-concentration formaldehyde (HCHO) together with ethanol\\/toluene\\/acetone\\/alpha-pinene (as an interference gas of HCHO) is detected with a micro gas sensor array, composed of eight tin oxide (SnO2) thin film gas sensors with Au, Cu, Pt or Pd metal catalysts. The characteristics of the multi-dimensional signals from the eight sensors are evaluated. A multilayer neural network with an error backpropagation (BP) learning

Pin Lv; Zhenan Tang; Guangfen Wei; Jun Yu; Zhengxing Huang

2007-01-01

330

Improved Resolution of Hydrocarbon Structures and Constitutional Isomers in Complex Mixtures Using Gas Chromatography-Vacuum  

E-print Network

Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry Gabriel Isaacman,*, Kevin R. Wilson, Arthur W, a variety of liquid and gas chromatography (LC and GC) techniques have been used with great success be confidently identified using traditional gas chromatography/mass spectrometry (GC/MS) techniques. This work

Cohen, Ronald C.

331

Effect of flow velocity and temperature on ignition characteristics in laser ignition of natural gas and air mixtures  

NASA Astrophysics Data System (ADS)

Laser induced spark ignition offers the potential for greater reliability and consistency in ignition of lean air/fuel mixtures. This increased reliability is essential for the application of gas turbines as primary or secondary reserve energy sources in smart grid systems, enabling the integration of renewable energy sources whose output is prone to fluctuation over time. This work details a study into the effect of flow velocity and temperature on minimum ignition energies in laser-induced spark ignition in an atmospheric combustion test rig, representative of a sub 15 MW industrial gas turbine (Siemens Industrial Turbomachinery Ltd., Lincoln, UK). Determination of minimum ignition energies required for a range of temperatures and flow velocities is essential for establishing an operating window in which laser-induced spark ignition can operate under realistic, engine-like start conditions. Ignition of a natural gas and air mixture at atmospheric pressure was conducted using a laser ignition system utilizing a Q-switched Nd:YAG laser source operating at 532 nm wavelength and 4 ns pulse length. Analysis of the influence of flow velocity and temperature on ignition characteristics is presented in terms of required photon flux density, a useful parameter to consider during the development laser ignition systems.

Griffiths, J.; Riley, M. J. W.; Borman, A.; Dowding, C.; Kirk, A.; Bickerton, R.

2015-03-01

332

On the mechanism of H atom production in hot filament activated H2 and CH4/H2 gas mixtures.  

PubMed

This article reports systematic measurements of the power utilization by Ta (and Re) hot filaments (HFs) operating in a poor vacuum, in pure He, N(2), and H(2), and in CH(4)/H(2) gas mixtures of relevance to diamond growth by HF chemical vapor deposition, as functions of filament temperature T(fil) (in the range of 1800-2700 K) and gas pressure p (in the range of 10(-2)-100 Torr). In the cases of H(2) and the CH(4)/H(2) gas mixtures, the power consumption studies are complemented by in situ measurements of the relative H atom densities [H] near the HF--which are seen to maximize at p approximately 10-20 Torr and thereafter to remain constant or, at the highest T(fil), to decline at higher p. These (and many previous) findings are rationalized by a companion theoretical analysis, which reduces the complex array of chemisorption and desorption processes that must contribute to the HF-surface mediated dissociation of H(2) to a two-step mechanism involving H atom formation by dissociative adsorption at bare (S(*)) sites and by desorption at hydrogenated (SH) sites on the HF surface. PMID:19655886

Comerford, Dane W; Smith, James A; Ashfold, Michael N R; Mankelevich, Yuri A

2009-07-28

333

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.

2010-01-01

334

Laboratory measurements and modeling of microwave absorption by ammonia in gas mixtures applicable to giant planet atmospheres  

NASA Technical Reports Server (NTRS)

Accurate knowledge of the microwave absorption behavior of ammonia is critical to the correct interpretation of radio astronomical and radio occultation data from the giant planets. New cavity resonator techniques developed at the Stanford Center for Radar Astronomy have allowed accurate laboratory measurements of the microwave absorptivity and refractivity spectra of gas mixtures containing trace amounts of ammonia. A parameterized version of the modified Ben-Reuven formalism of Berge and Bulkis was optimized to fit the new data. The new formalism produced by this method predicts ammonia absorptivity much more accurately than previous formalism over a significant range of conditions.

Spilker, T. R.

1990-01-01

335

A preliminary investigation into a simple method for the determination of the mean ionisation energy of gas mixtures used in the NPL primary gas counting system.  

PubMed

The activity concentration of gaseous beta-emitting radionuclides such as (3)H, (85)Kr and, more recently, (11)C, is measured at NPL using a set of length-compensated proportional counters. The active gas is mixed with argon-methane (P-10) and passed to the counters. Adding gases to P-10 changes the mean ionisation energy, W, of the gas mixture. Estimation of the counting losses using the Monte Carlo model requires a knowledge of W. Unfortunately, only a limited amount of published data is available. This paper describes the initial experimental studies performed to enable the extension of the MC model based loss correction method to gases other than carbon dioxide in P-10. Preliminary measurements have been made to determine the W value for a gas mixture containing (85)Kr in nitrogen and P-10. The DC current through the counters is measured; the counters are also operated in the normal way with pulse amplifiers, discriminators and scalers. The value of W is derived from a knowledge of activity, counter current and mean beta energy. PMID:22609128

Phillips, H C; Sephton, J P; Johansson, L C; Dean, J C J

2012-09-01

336

Development of a functionalized Xenon biosensor  

SciTech Connect

NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of remote amplified detection. Here we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of functionalized xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

Spence, Megan M.; Ruiz, E. Janette; Rubin, Seth M.; Lowery, Thomas J.; Winssinger, Nicolas; Schultz, Peter G.; Wemmer, David E.; Pines, Alexander

2004-03-25

337

[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

1987-01-01

338

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

339

Relation of breathing oxygen-argon gas mixtures to altitude decompression sickness.  

PubMed

A 95% oxygen-5% argon breathing mixture produced by a molecular sieve generator was shown to be similar to a 95% O2-5% N2 mixture for breathing during 1-h exposures at 7,620 m (25,000 ft) or 10,972 m (35,000 ft), as determined by the detection of proportionate numbers of intravascular bubbles in the pulmonary artery of dogs. Comparable results were obtained with 95% O2-5% He or 100% O2. The partial pressures of a 5% mixture at 7,620 and 10,972 m were 14.1 and 8.6 torr, respectively, and were apparently low enough so that the nonmetabolizable gases did not result in differences in the incidence of intravascular bubble formation or decompression sickness. Argon at the 10% level showed a nonsignificant trend to produce more bubbles. Individual susceptibility or resistance to form bubbles was observed with the different gases. Denitrogenation with either 5 or 10% mixtures of the inert gases was quite effective, as shown by a reduction in the number of intravascular bubbles detected. PMID:7417112

Cooke, J P; Ikels, K G; Adams, J D; Miller, R L

1980-06-01

340

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

341

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

342

Decomposition products from negative and 50 Hz ac corona discharges in compressed SF6 and SF6\\/N2 (10:90) mixtures. Effect of water vapour added to the gas  

Microsoft Academic Search

SF6\\/N2 mixtures with a majority of nitrogen are currently highly recommended, at the international level, in gas insulated transmission lines as an alternative to pure SF6; indeed, these mixtures are much more friendly to the atmosphere and particularly cheap. Among the areas of investigation of such gas mixtures, their electrical decomposition as a function of impurity content and type of

L. Vial; A. M. Casanovas; I. Coll; J. Casanovas

1999-01-01

343

Reduced xenon diffusion for quantitative lung study--the role of SF(6)  

NASA Technical Reports Server (NTRS)

The large diffusion coefficients of gases result in significant spin motion during the application of gradient pulses that typically last a few milliseconds in most NMR experiments. In restricted environments, such as the lung, this rapid gas diffusion can lead to violations of the narrow pulse approximation, a basic assumption of the standard Stejskal-Tanner NMR method of diffusion measurement. We therefore investigated the effect of a common, biologically inert buffer gas, sulfur hexafluoride (SF(6)), on (129)Xe NMR and diffusion. We found that the contribution of SF(6) to (129)Xe T(1) relaxation in a 1:1 xenon/oxygen mixture is negligible up to 2 bar of SF(6) at standard temperature. We also measured the contribution of SF(6) gas to (129)Xe T(2) relaxation, and found it to scale inversely with pressure, with this contribution approximately equal to 1 s for 1 bar SF(6) pressure and standard temperature. Finally, we found the coefficient of (129)Xe diffusion through SF(6) to be approximately 4.6 x 10(-6) m(2)s(-1) for 1 bar pressure of SF(6) and standard temperature, which is only 1.2 times smaller than the (129)Xe self diffusion coefficient for 1 bar (129)Xe pressure and standard temperature. From these measurements we conclude that SF(6) will not sufficiently reduce (129)Xe diffusion to allow accurate surface-area/volume ratio measurements in human alveoli using time-dependent gas diffusion NMR.

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

2000-01-01

344

Column Calibration Factor to Study the Composition Dependence of the Thermal Diffusion Factors of Inert Gas Mixtures  

NASA Astrophysics Data System (ADS)

The experimental thermal diffusion factors ?T of He4-Ar40 and Ne20-Xe132 gas mixtures at different compositions of the lighter components and an isotopic natural mixture of Ne20-Ne22 are estimated at the mean temperature \\bar{T}{=}340 K by the column calibration factor method from the available values of ln qe(qe being the equilibrium separation factor) for those mixtures at different pressures in atmosphere for each composition, measured by J. M. Saviron et al. in a thermal diffusion column with the column calibration factor Fs{=}3.946, the value (at \\bar{T}{=}340 K) derived from the formula Fs{=}68.94796-0.3174514 \\bar{T}+3.71383× 10-4T2 as obtained by S. Acharyya et al. It is shown that the experimental ?T’s, thus estimated with the help of Fs and ln qmax, agree excellently with those due to the existing methods using molecular models as well as with those due to Slieher’s model-independent method, so far as their magnitudes and the trends of their variation with the mole fraction of the lighter components are concerned. This suggests that the present method is a unique one which can safely be used to study the composition dependence of ?T in both the isotopic and nonisotopic cases.

Datta, A. K.; Dasgupta, G.; Acharyya, S.

1990-10-01

345

Use of a solid mixture containing diethylenetriamine/nitric oxide (DETANO) to liberate nitric oxide gas in the presence of horticultural produce to extend postharvest life.  

PubMed

Postharvest treatment of fruit and vegetables with a low concentration of nitric oxide gas can extend postharvest life but application of nitric oxide by release from a gas cylinder is not feasible for many horticultural situations. This paper reports on development of a solid mixture to generate nitric oxide gas in the presence of horticultural produce. The solid NO-donor compound, diethylenetriamine/nitric oxide (DETANO) was found to quantitatively liberate nitric oxide in the presence of a range of acidic substances including citric acid. A solid mixture of DETANO and citric acid with wheat starch added as a filler and moisture absorbent in the ratio of 1:10:20 was found to be stable for at least six months when stored in dry air. However, in humid air, absorption of moisture from the atmosphere led to reaction of DETANO with citric acid and the evolution of nitric oxide gas. When the dry mixture was placed in a container with strawberry and mushroom, the moisture given off by produce activated the mixture and resulted in a similar extension in postharvest life as achieved by direct fumigation with nitric oxide gas. Commercial use of such a solid mixture could be through tablets or sachets which are more manageable in a farm or packing house than gas fumigation. PMID:17604663

Wills, R B H; Soegiarto, L; Bowyer, M C

2007-08-01

346

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

347

Experimental and simulation studies of iron oxides for geochemical fixation of CO2-SO2 gas mixtures  

USGS Publications Warehouse

Iron-bearing minerals are reactive phases of the subsurface environment and could potentially trap CO2-SO2 gas mixtures derived from fossil fuel combustion processes by their conversion to siderite (FeCO 3) and dissolved sulfate. Changes in fluid and mineral compositions resulting from reactions, involving the co-injection of SO2 with CO2 were observed both theoretically and experimentally. Experiments were conducted with a natural hematite (??-Fe2O3) sample. A high pressure-high temperature apparatus was used to simulate conditions in geologic formations deeper than 800 m, where CO2 is in the supercritical state. Solid samples were allowed to react with a NaCl-NaOH brine and SO2-bearing CO2-dominated gas mixtures. The predicted equilibrium mineral assemblage at 100??C and 250 bar became hematite, dawsonite (NaAl(OH)2CO3), siderite (FeCO 3) and quartz (SiO2). Experimentally, siderite and dawsonite, derived from the presence of kaolinite (Al2Si 2O5(OH)4) in the parent material, were present in residual solids at longer reaction time intervals, which agreed well with results from the modelling work. ?? 2011 Published by Elsevier Ltd.

Garcia, S.; Rosenbauer, R.J.; Palandri, J.; Maroto-Valer, M. M.

2011-01-01

348

[Application of least square support vector machine based on particle swarm optimization in quantitative analysis of gas mixture].  

PubMed

According to the difficulty in selecting parameter of least square support vector machine (LS-SVM) when modeling on the gas mixture, and the high computational complexity of the infrared spectrum data, LS-SVM optimized by particle swarm optimization (PSO) algorithm was proposed to build an infrared spectrum quantitative analysis model with feature extracted by principal component analysis (PCA). Firstly, seven feature variables were extracted by PCA as the input of the model from 550 infrared spectrum data of the main absorption apex field, so the computational complexity was reduced. This model aimed at three components of gas mixture, in which methane, ethane and propane gases are included. The concentration of each component ranged from 0.1% to 1%, 0.1% to 1% and 0.1% to 1.5% respectively. Each component quantitative analysis model was built by LS-SVM and the parameters were optimized by PSO algorithm, then the regression model would be reconstructed according to the optimal parameters. This method replaced the traditional ergodic optimization. The experiment results show that the time of offline modeling by PSO was reduced to one fortieth of that of ergodic optimizing. The precision of the model was corresponsive. It can meet the requirement of the measure. PSO algorithm has more superior performance on global optimization and convergence speed. So it is feasible to combine PSO algorithm with LS-SVM to create the infrared spectrum quantitative analysis model. It has definite practice significance and application value. PMID:20496707

Li, Yu-Jun; Tang, Xiao-Jun; Liu, Jun-Hua

2010-03-01

349

Detection of brown adipose tissue and thermogenic activity in mice by hyperpolarized xenon MRI.  

PubMed

The study of brown adipose tissue (BAT) in human weight regulation has been constrained by the lack of a noninvasive tool for measuring this tissue and its function in vivo. Existing imaging modalities are nonspecific and intrinsically insensitive to the less active, lipid-rich BAT of obese subjects, the target population for BAT studies. We demonstrate noninvasive imaging of BAT in mice by hyperpolarized xenon gas MRI. We detect a greater than 15-fold increase in xenon uptake by BAT during stimulation of BAT thermogenesis, which enables us to acquire background-free maps of the tissue in both lean and obese mouse phenotypes. We also demonstrate in vivo MR thermometry of BAT by hyperpolarized xenon gas. Finally, we use the linear temperature dependence of the chemical shift of xenon dissolved in adipose tissue to directly measure BAT temperature and to track thermogenic activity in vivo. PMID:25453088

Branca, Rosa Tamara; He, Ting; Zhang, Le; Floyd, Carlos S; Freeman, Matthew; White, Christian; Burant, Alex

2014-12-16

350

Generation of microwave-induced plasmas in automotive exhaust gas mixtures using pulsed microwave energy.  

PubMed

Microwave energy at 2.45 GHz was applied to a mixture of exhaust gases from a petrol engine at atmospheric pressure. It was found that by pulsing the microwave energy with a 50% duty cycle, the average power required to sustain a microwave-induced plasma discharge was decreased by about 40%. The ratio of absorbed to incident power was unaffected. These findings were confirmed for pulse frequencies from 10 to 300 Hz. PMID:15007864

Destefani, Carlos A; Siores, Elias; Murphy, Anthony B

2003-01-01

351

Design of Solid Form Xenon124 Target for Producing I-123 Radioisotope Using Computer Simulation Techniques  

Microsoft Academic Search

Recently in Cyclotron and Nuclear Medicine Department of NRCAM, at Atomic Energy organization of Iran (AEOI), a system for producing 1-123 via Xe-124 gas target technology, has been constructed and installed. One of the major problems in this system is the highly expensive cost of the enriched Xenon-124 gas. Therefore, saving this gas inside the system is very important. Unfortunately,

K. Kamali Moghaddam; M. Sadeghi; T. Kakavand; S. Shokri Bonab

2006-01-01

352

The XENON dark matter experiment , E. Aprileb  

E-print Network

The XENON dark matter experiment T. Shutta , E. Aprileb , E. Baltzb , K. Gibonib , P. Majewskib , M Laboratory, Livermore, CA 94550 We report on progress of the XENON collaboration, which is developing a liquid xenon time projection chamber technology for use in a very-large-mass dark matter experiment

McDonald, Kirk

353

Effect of Non-condensable gas on Solutal Marangoni Condensation Heat Transfer Characteristics for Water-Ethanol Vapor Mixture  

NASA Astrophysics Data System (ADS)

The condensation heat transfer characteristic curves for ternary vapor mixture of water, ethanol and air (or nitrogen) under the ethanol mass fraction of 0.01, 0.07, 0.25, 0.45 and relatively low concentrations of air (or nitrogen) were measured.The effect of air (or nitrogen) as a non-condensable gas on several different domains in the Marangoni condensation characteristic curves was discussed. It was shown that the effect of non-condensable gas in the domains controlled by the diffusion resistance and the filmwise condensation was not notable but in the domain dominated by the condensate resistance of dropwise mode was remarkable. Moreover, the variations of the several characteristic points representing the characteristic curves caused by the change in non-condensable gas concentration were discussed. The deteriorations of the maximum heat transfer coefficient and the maximum heat flux for low ethanol concentration and low concentration of non-condensable gas, in which the excellent heat transfer characteristics were exhibited, were more remarkable.

Wang, Shixue; Utaka, Yoshio

354

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

355

Non-equilibrium Thermodynamics approach to Transport Processes in Gas Mixtures  

E-print Network

The thermodynamic approach to non-equilibrium dynamics describes the state of macroscopic systems by means of a collection of intensities or intensive variables. The latter are by definition the differentials of the entropy with respect to the set of extensive constraints. The environment is directly involved in controlling the intensities. The isolation paradigm is negated. The general principles substanciating the approach are restated and expanded to multi-component systems. The procedure is applied to the prediction of transport processes (viscosity and thermal conductivity) of mixtures of atomic gases. Theoretical results are compared with published experimental data.

Z. Hens; X. de Hemptinne

1996-04-16

356

CONTROL OF LASER RADIATION PARAMETERS: Short pulse formation in a TEA CO2 laser using a CO2 — N2 — H2 gas mixture  

NASA Astrophysics Data System (ADS)

The use of an optimal CO2 — N2 — H2 gas mixture with a high concentration of hydrogen (30% — 40%) was shown to allow the formation of high-power TEA CO2-laser pulses with a base duration of ~ 200 ns whose energy and peak power significantly exceed the parameters of pulses obtained in binary CO2 — H2 mixtures. Considering all the parameters, the helium-free 56% CO2 — 14% N2 — 30% H2 gas mixture at a pressure of 0.7 atm is optimal for the generation of short high-power pulses in the TEA CO2 laser. A small addition of nitrogen ([CO2]/[N2] ~ 10 — 12) to the binary CO2 — H2 mixture not only substantially increases the pulse energy and peak power (by a factor of 3 — 3.5) but also shortens their duration at half-maximum with retention of the total (base) duration.

Ivashchenko, M. V.; Karapuzikov, A. I.; Sherstov, I. V.

2001-11-01

357

Calibrating the Xenon10 Detector with Activated Xenon  

NASA Astrophysics Data System (ADS)

Xenon10 is a 15-kg liquid xenon (LXe) detector for the search of dark matter in the form of weakly interacting massive particles (WIMPs). The high scintillation yield of LXe and high light collection efficiency in Xenon10 allow the detection of low-energy nuclear recoils, e.g. from WIMPs elastic scattering, down to 10 keV. The energy calibration is usually performed by using external gamma ray sources, such as Co-57 and Cs-137. However, external low-energy gamma rays are not very useful to calibrate the central part of the detector due to their small interaction length (˜mm) in LXe. Calibrations from external high-energy gamma rays are also not accurate due to gamma-ray's non-uniform distributions in the target and non-linearity of LXe scintillation yield for different energies. Here we introduce a new calibration method by using neutron-activated xenon, which emits 164 keV and 236 keV gamma rays uniformly in the target and provides precise energy calibration in every part of the detector. The method also allows the study of position-dependence of the signals, further improving the detector's energy resolution and background rejection capability.

Ni, Kaixuan

2007-04-01

358

Featuring Of Odor By Metal Oxide Sensor Response To Varying Gas Mixture  

NASA Astrophysics Data System (ADS)

In this report the responses of metal oxide sensors to varying amount of gas in air are used for multiparameter featuring of volatile compounds. The composition of the atmosphere is varied by time dependent release of gas from a SPME fiber into flow of synthetic air. Sensor outputs are described by sets of parameters related to the characteristics of gas injection and the sensor response kinetics. The sets of sensor parameters are processed by explorative data analysis (EDA) software comprising customizable feature, correlation and principal component analysis (PCA). This method is applied for distinguishing between four volatile compounds acetone, acetic acid, acetaldehyde and butyric acid, and is aimed at recognition of compounds emitted from infected wounds that is the subject of the WOUNDMONITOR project. The amounts of the target compounds can be evaluated by the EDA analysis if the magnitudes of signals are processed. Analysis of pure dynamic parameters results in separation between the types of the volatile compounds.

Šetkus, Arunas; Olekas, Andrius; Senulien?, Daiva; Falasconi, Matteo; Pardo, Matteo; Sberveglieri, Giorgio

2009-05-01

359

Device for two-dimensional gas-phase separation and characterization of ion mixtures  

DOEpatents

The present invention relates to a device for separation and characterization of gas-phase ions. The device incorporates an ion source, a field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer, an ion mobility spectrometry (IMS) drift tube, and an ion detector. In one aspect of the invention, FAIMS operating voltages are electrically floated on top of the IMS drift voltage. In the other aspect, the FAIMS/IMS interface is implemented employing an electrodynamic ion funnel, including in particular an hourglass ion funnel. The present invention improves the efficiency (peak capacity) and sensitivity of gas-phase separations; the online FAIMS/IMS coupling creates a fundamentally novel two-dimensional gas-phase separation technology with high peak capacity, specificity, and exceptional throughput.

Tang, Keqi (Richland, WA); Shvartsburg, Alexandre A. (Richland, WA); Smith, Richard D. (Richland, WA)

2006-12-12

360

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

361

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

362

Collisional 3He and 129Xe frequency shifts in Rb-noble-gas mixtures.  

PubMed

The Fermi-contact interaction that characterizes collisional spin exchange of a noble gas with an alkali-metal vapor also gives rise to NMR and EPR frequency shifts of the noble-gas nucleus and the alkali-metal atom, respectively. We have measured the enhancement factor ?0 that characterizes these shifts for Rb-129Xe to be 493±31, making use of the previously measured value of ?0 for Rb-3He. This result allows accurate 129Xe polarimetry with no need to reference a thermal-equilibrium NMR signal. PMID:21668151

Ma, Z L; Sorte, E G; Saam, B

2011-05-13

363

Collisional {sup 3}He and {sup 129}Xe Frequency Shifts in Rb-Noble-Gas Mixtures  

SciTech Connect

The Fermi-contact interaction that characterizes collisional spin exchange of a noble gas with an alkali-metal vapor also gives rise to NMR and EPR frequency shifts of the noble-gas nucleus and the alkali-metal atom, respectively. We have measured the enhancement factor {kappa}{sub 0} that characterizes these shifts for Rb-{sup 129}Xe to be 493{+-}31, making use of the previously measured value of {kappa}{sub 0} for Rb-{sup 3}He. This result allows accurate {sup 129}Xe polarimetry with no need to reference a thermal-equilibrium NMR signal.

Ma, Z. L.; Sorte, E. G.; Saam, B. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah, 84112-0830 (United States)

2011-05-13

364

[Hypoxic gas mixture delivery due to a defective vaporiser manifold: case report, review of the literature and suggested emergency management algorithm].  

PubMed

A case of delivery of a hypoxic gas mixture to a patient during total intravenous anesthesia is described. A progressive fall in inspiratory oxygen concentration followed by a drop in oxygen saturation below 90?% occurred during the advanced stages of a hitherto uneventful general anesthesia of a female patient undergoing anterior cervical fusion surgery. A malfunctioning defective rubber seal of a vaporizer manifold was identified as the cause of the gas leak. The leak had not been detected during the preanesthesia leak test. The problem of hypoxic gas mixtures and uncommon leaks in modern anesthesia equipment is discussed. The importance of locating a leak in the high or low pressure circuits is explained. An algorithm for the management of an unexpected decrease of inspiratory oxygen concentration or any other manifestation of a gas leak along with a systematic approach to locating the source of a gas leak is presented. PMID:24584839

Berlet, T

2014-04-01

365

Influence of CO2-Ar Mixtures as Shielding Gas on Laser Welding of Al-Mg Alloys  

NASA Astrophysics Data System (ADS)

In this study, AA5083 samples were butt welded under a conduction regime with high-power diode laser (HPDL). Various mixtures composed of Ar and CO2 were used as a shielding gas. The influence of the shielding gas composition on the microstructure and on the properties of laser welds was analyzed. The weld beads were deeply characterized by metallographic/microstructural studies, X-ray diffraction (XRD), X-ray energy dispersive spectrometry (X-EDS) chemical analyses, X-ray photoelectron spectra (XPS), microhardness, and tensile strength. The corrosion resistance of laser-remelted surfaces with different CO2/Ar ratios was also estimated by means of electrochemical tests. The addition of CO2 to the shielding gas results in a better weld penetration and oxidizes the weld pool surface. This addition also promotes the migration of Mg toward the surface of weld beads and induces the formation of magnesium aluminates spinel on the welds. The best corrosion resistance result is achieved with 20 pct CO2. The overall results indicate that the addition of small percentage of CO2 to Ar leads to improvements of the mechanical and corrosion properties of the aluminum welds.

Boukha, Zouhair; Sánchez-Amaya, José María; González-Rovira, Leandro; Rio, Eloy Del; Blanco, Ginesa; Botana, Javier

2013-12-01

366

A program for calculating expansion-tube flow quantities for real-gas mixtures and comparison with experimental results  

NASA Technical Reports Server (NTRS)

A computer program written in FORTRAN 4 language is presented which determines expansion-tube flow quantities for real test gases CO2 N2, O2, Ar, He, and H2, or mixtures of these gases, in thermochemical equilibrium. The effects of dissociation and first and second ionization are included. Flow quantities behind the incident shock into the quiescent test gas are determined from the pressure and temperature of the quiescent test gas in conjunction with: (1) incident-shock velocity, (2) static pressure immediately behind the incident shock, or (3) pressure and temperature of the driver gas (imperfect hydrogen or helium). The effect of the possible existence of a shock reflection at the secondary diaphragm of the expansion tube is included. Expansion-tube test-section flow conditions are obtained by performing an isentropic unsteady expansion from the conditions behind the incident shock or reflected shock to either the test-region velocity or the static pressure. Both a thermochemical-equilibrium expansion and a frozen expansion are included. Flow conditions immediately behind the bow shock of a model positioned at the test section are also determined. Results from the program are compared with preliminary experimental data obtained in the Langley 6-inch expansion tube.

Miller, C. G., III

1972-01-01

367

Carcase and meat quality in broilers either killed with a gas mixture or stunned with an electric current under commercial processing conditions.  

PubMed

1. Carcase and meat quality were evaluated under commercial conditions in 400 broilers either killed with a mixture of 30% carbon dioxide and 60% argon in air or stunned with a 50 Hz AC with clipped sine wave. 2. Compared with electrical stunning, killing broilers with the gas mixture eliminated or substantially reduced the prevalence of carcase and meat quality defects. 3. The results also showed that killing broilers with a mixture of 30% carbon dioxide and 60% argon would enable filleting (deboning) to be performed at 4 h post mortem without adversely affecting the cook loss or texture of breast meat. PMID:9158892

Raj, A B; Wilkins, L J; Richardson, R I; Johnson, S P; Wotton, S B

1997-05-01

368

Luminescence characteristics of Xe2Cl excimer molecules under pumping the dense Xe—CCl4 gas mixtures with a pulsed electron beam  

NASA Astrophysics Data System (ADS)

Temporal and spectral characteristics of the luminescence of dense Xe—CCl4 gas mixtures of different composition, excited by a 5-ns pulsed electron beam, were measured. The energy of the electrons amounted to 150 keV and the electron beam current pulse amplitude was 5 A. The gas mixtures were used containing Xe (38-700 Torr) and CCl4 (0.03-0.3 Torr). The studies were performed within the wavelength range 200-1200 nm using a MAYA-2000Pro diffraction grating spectrometer and a RIGOL DS 5022 ME fast digital oscilloscope. The luminescence lifetimes of the excimer molecules XeCl* (band with ?max = 308 nm) and Xe2Cl* (band with ?max = 486 nm) were measured, as well as the constants of quenching by the components of the gas mixture for Xe2Cl* molecules. A model of plasma-chemical processes for dense Xe—CCl4 gas mixtures with a very low content of the CCl4 donor is proposed. It is shown that in such 'poor' mixtures Xe2Cl* molecules are mainly produced as a result of recombination of the Xe2+ and Cl- ions.

Mis'kevich, A. I.; Jinbo, Guo

2013-05-01

369

Luminescence characteristics of Xe{sub 2}Cl excimer molecules under pumping the dense Xe-CCl{sub 4} gas mixtures with a pulsed electron beam  

SciTech Connect

Temporal and spectral characteristics of the luminescence of dense Xe-CCl{sub 4} gas mixtures of different composition, excited by a 5-ns pulsed electron beam, were measured. The energy of the electrons amounted to 150 keV and the electron beam current pulse amplitude was 5 A. The gas mixtures were used containing Xe (38-700 Torr) and CCl{sub 4} (0.03-0.3 Torr). The studies were performed within the wavelength range 200-1200 nm using a MAYA-2000Pro diffraction grating spectrometer and a RIGOL DS 5022 ME fast digital oscilloscope. The luminescence lifetimes of the excimer molecules XeCl* (band with {lambda}{sub max} = 308 nm) and Xe{sub 2}Cl* (band with {lambda}{sub max} = 486 nm) were measured, as well as the constants of quenching by the components of the gas mixture for Xe{sub 2}Cl* molecules. A model of plasma-chemical processes for dense Xe-CCl{sub 4} gas mixtures with a very low content of the CCl{sub 4} donor is proposed. It is shown that in such 'poor' mixtures Xe{sub 2}Cl* molecules are mainly produced as a result of recombination of the Xe{sub 2}{sup +} and Cl{sup -} ions. (active media)

Mis'kevich, A I; Jinbo, Guo [National Research Nuclear University 'Moscow Engineering Physics Institute', Moscow (Russian Federation)] [National Research Nuclear University 'Moscow Engineering Physics Institute', Moscow (Russian Federation)

2013-05-31

370

Analysis of the insulation characteristics of CF3I gas mixtures with Ar, Xe, He, N2, and CO2 using Boltzmann equation method  

NASA Astrophysics Data System (ADS)

The present study is devoted to the calculation of electron swarm parameters, including the reduced effective ionization coefficient, electron mean energy, and electron drift velocity, for the gas mixtures of CF3I with Ar, Xe, He, N2, and CO2. These data are computed by employing the Boltzmann equation method with two-term approximation in the condition of steady-state Townsend (SST) discharge. For the purpose of evaluating the insulation strength of CF3I gas mixtures, values of the limiting field strength (E/N)lim for which the ionization exactly balances the electron attachment are determined from the variation curves of (? - ?)/N. The results indicate that mixtures of CF3I-N2 present the greatest insulation strength among all the combinations for CF3I content varied from 20 to 90%. Furthermore, the gas mixture with 70% CF3I can achieve a very similar dielectric strength to that of SF6. The concerned liquefaction issues are also taken into account to fully assess the possibility of applying CF3I gas mixtures in power equipment as an insulation medium.

Deng, Yunkun; Xiao, Dengming

2014-09-01

371

Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow  

NASA Technical Reports Server (NTRS)

Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

Srinivasan, G.; Smith, J. A.

1976-01-01

372

Evidence for double incoherent Raman scattering in binary gas mixtures: SF{sub 6}-N{sub 2}  

SciTech Connect

We report a collision-induced Raman band by room temperature gas mixtures of sulfur hexafluoride and nitrogen. The band is centered at the sum of the frequencies of the symmetric-stretching nu{sub 1} transition of SF{sub 6} and the fundamental transition of N{sub 2}, and its intensity scales as the product of the partial densities of the gases. The observed process is evidence of double incoherent Raman scattering (DRS) by SF{sub 6}-N{sub 2}, in which both molecules simultaneously undergo two Raman-allowed transitions. The band was found to be almost fully depolarized, in agreement with previous observations in other systems and with theoretical predictions. Its integrated intensity is about one-third higher than the total area predicted by the leading-order dipole-induced dipole model. This discrepancy suggests that DRS is a practical means of assessing the quality of intermolecular potential models, which, in the case of SF{sub 6}-N{sub 2}, is still believed to be not good enough. Our work is expected to open the door to a multitude of studies involving complicated processes encountered in nonpolar gases and their mixtures, which are of direct relevance to atmospheric research.

Verzhbitskiy, I. A.; Chrysos, M.; Rachet, F.; Kouzov, A. P. [Laboratoire des Proprietes Optiques des Materiaux et Applications, UMR CNRS 6136, Universite d'Angers, 2 boulevard Lavoisier, F-49045 Angers (France); Institute of Physics, Saint Petersburg State University, Ulyanovskaya str. 1, Peterhof, Saint Petersburg 198504 (Russian Federation)

2010-01-15

373

Gas-phase positive and negative ion/molecule reactions in diborane and silane/diborane mixtures  

NASA Astrophysics Data System (ADS)

The gas phase ion chemistry of diborane and of silane/diborane mixtures was studied by ion trap mass spectrometry (ITMS), in both positive and negative ionization mode. Positive ion/molecule reactions in diborane mainly proceed through H2 or BH3 loss and lead to formation of B hydride clusters containing up to six B atoms, while in negative ionization clustering reactions proceed to a higher degree with formation of B8Hn- ions. In the silane/diborane system, the main ion/molecule reactions leading to ions containing both silicon and boron atoms were identified and rate constants of the main processes were determined for positive ions. In positive ionization, Si/B ions are mainly formed in reactions of few diborane ions with silane, while reactions of silane ions with B2H6 yield B2H5+ as the main product. Negative ionization of the same mixture produces a much larger amount of Si/B ionic species, due to several reactions of silane anions with diborane, resulting in BH3 or H2 neutral losses. These results indicate that negative ions may play an important role in formation of Si/B ion clusters in plasma chemical vapour deposition processes for production of semiconductor and photovoltaic materials.

Operti, Lorenza; Rabezzana, Roberto; Turco, Francesca; Vaglio, Gian Angelo

2007-06-01

374

Reactive Ion Etching Texturing for Multicrystalline Silicon Solar Cells Using a SF6/O2/Cl2 Gas Mixture  

NASA Astrophysics Data System (ADS)

Maskless random reactive ion etching (RIE) texturing employing a SF6/O2/Cl2 gas mixture was investigated in order to achieve higher efficiencies in multicrystalline silicon (mc-Si) solar cells. Triangular pyramid structures with an aspect ratio of 1 were formed and, when the RIE power increased, the average reflectance was reduced by about 1.46% per 10 W. This was due to the increased density of the surface features. The performances of all of the RIE-textured mc-Si solar cells were improved compared with that of the reference cell. Among them, the 110 W cell, which had a 0.6% higher efficiency than the reference cell, had the highest efficiency of 16.82%. An impedance analysis was carried out to determine series resistance (Rs), shunt resistance (Rsh), and junction capacitance (Cj). Interestingly, the cell with higher efficiencies and higher structure densities had higher linear reverse currents.

Mook Park, Kwang; Bok Lee, Myoung; Jeon, Kyeong Su; Choi, Sie Young

2013-03-01

375

Breathing gas mixtures different from air: an adaptation for survival under the ice of a facultative air-breathing fish.  

PubMed

Gaseous respiration by central mudminnows (Umbra limi), particularly their use of bubbles composed of gas mixtures other than air, may have evolved as an adaptation to the oxygen-depleted, carbon dioxide-rich water of winterkill lakes. Under simulated winterkill conditions, mudminnows frequently engulfed gaseous bubbles. Use of bubbles was not related to varying methane or nitrogen content (0 to 80 percent) when all bubbles contained 20 percent oxygen. When the oxygen content of bubbles varied (0 to 20 percent), fish visited bubbles randomly but remained longer and took fewer "breaths" at bubbles with high oxygen content. High temperature (16 degrees to 34 degrees C) and low pH (6.8 to 4.5) did not stimulate increased air-breathing when dissolved oxygen was sufficient. PMID:17732920

Magnuson, J J; Keller, J W; Beckel, A L; Gallepp, G W

1983-04-15

376

Low-pressure plasma-etching of bulk polymer materials using gas mixture of CF4 and O2  

NASA Astrophysics Data System (ADS)

In this study, we have proposed a low-pressure reactive ion etching of bulk polymer materials with a gas mixture of CF4 and O2, and have achieved precise fabrication of poly(methyl methacrylate) (PMMA) and perfluoroalkoxy (PFA) bulk polymer plates with high-aspect-ratio and narrow gap array structures, such as, pillar, frustum, or cone, on a nano/micro scale. The effects of the etching conditions on the shape and size of each pillar were evaluated by changing etching duration and the size/material of etching mask. The fabricated PMMA array structures indicate possibilities of optical waveguide and nanofiber array. PFA cone array structures showed super-hydrophobicity without any chemical treatments. Also, polystyrene-coated silica spheres were used as an etching mask for the pillar array structure formation to control the gap between pillars.

Nabesawa, Hirofumi; Hiruma, Takaharu; Hitobo, Takeshi; Wakabayashi, Suguru; Asaji, Toyohisa; Abe, Takashi; Seki, Minoru

2013-11-01

377

Quench gases for xenon- (and krypton-) filled proportional counters  

NASA Technical Reports Server (NTRS)

Xenon-filled proportional counters are used extensively in astronomy, particularly in the hard X-ray region. The choice of quench gas can have a significant effect on the operating characteristics of the instrument although the data necessary to make the choice are not easily obtainable. Results which detail the performance obtained from both cylindrical and parallel field geometries for a wide variety of readily available, ultrahigh or research grade purity, quench gases are presented.

Ramsey, B. D.; Agrawal, P. C.

1988-01-01

378

The adsorption of argon, krypton and xenon on activated charcoal  

SciTech Connect

Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs.

Underhill, D.W. [Univ. of South Carolina, Columbia, SC (United States)

1996-08-01

379

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

380

Modeling Pulse Characteristics in Xenon with NEST  

E-print Network

A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, effects such as the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, parameters such as ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

Mock, Jeremy; Kazkaz, Kareem; Szydagis, Matthew; Tripathi, Mani; Uvarov, Sergey; Woods, Michael; Walsh, Nicholas

2013-01-01

381

Two-fluid dust and gas mixtures in smoothed particle hydrodynamics: a semi-implicit approach  

NASA Astrophysics Data System (ADS)

A method to avoid the explicit time integration of small dust grains in the two-fluid gas/dust smoothed particle hydrodynamics (SPH) approach is proposed. By assuming a very simple exponential decay model for the relative velocity between the gas and dust components, all the effective characteristics of the drag force can be reproduced. A series of tests has been performed to compare the accuracy of the method with analytical and explicit integration results. We find that the method performs well on a wide range of tests, and can provide large speed-ups over explicit integration when the dust stopping time is small. We have also found that the method is much less dissipative than conventional explicit or implicit two-fluid SPH approaches when modelling dusty shocks.

Lorén-Aguilar, Pablo; Bate, Matthew R.

2014-09-01

382

Catalytic combustion of low heating value gas mixtures: comparison between laboratory and pilot scale tests  

Microsoft Academic Search

Catalytic combustion of low heating value fuels is a promising method for electricity production combining the use of a renewable fuel with ultra-low emissions. In the present work, catalytic combustion of a low heating value gas has been studied over monolithic catalysts in an atmospheric 30kW pilot catalytic combustor connected to a wood pellet gasifier. The results have been compared

Magnus Berg; E Magnus Johansson; Sven G Järås

2000-01-01

383

Results from the XENON10 Dark Matter search experiment at Gran Sasso Laboratories  

SciTech Connect

One of the most appealing questions in astroparticle physics concerns the nature of the Dark Matter (DM) particles and their possible interaction with ordinary matter. In order to find a solution to such problem, a double phase liquid-gas Xenon Time Projection Chamber has been proposed and built as a suitable detector for the direct detection of DM in the form of Weakly Interacting Massive Particles (WIMPs). The possibility of simultaneously measuring the scintillation and the ionization signals, and a 3D event localization feature, represent a powerful background discrimination method. During the Autumn-Winter 2006-2007 a prototype of 15 kg sensitive mass of Liquid Xenon (XENON10) has been successfully run at the Gran Sasso Underground Laboratory. The technique and the results of the XENON10 detector are presented.

Ferella, Alfredo Davide [RWTH Aachen University, Physics Department, Sommerfeldstr. 14, 52074 Aachen (Germany)

2007-11-20

384

Ultrapyrolytic upgrading of plastic wastes and plastics/heavy oil mixtures to valuable light gas products  

SciTech Connect

Viable operating conditions were identified experimentally for maximizing the production of high-value products such as ethylene, propylene, styrene, and benzene, from the ultrapyrolysis of waste plastics. Using both a batch microreactor and a pilot-plant-sized reactor, the key operating variables considered were pyrolysis temperature, product reaction time, and quench time. In the microreactor experiments, polystyrene (PS), a significant component of waste plastics, was pyrolyzed at temperatures ranging from 800 to 965 C, with total reaction times ranging from 500 to 1,000 ms. At a temperature of 965 C and 500 ms, the yields of styrene plus benzene were greater than 95 wt %. In the pilot-plant experiments, the recently patented internally circulating fluidized bed (ICFB) reactor (Milne et al., US Patent Number 5,370,789, 1994b) was used to ultrapyrolyze low-density polyethylene (LDPE) in addition to LDPE (5% by weight)/heavy oil mixtures at a residence time of 600 ms. Both experiments produced light olefin yields greater than 55 wt % at temperatures above 830 C.

Lovett, S.; Berruti, F.; Behie, L.A. [Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering] [Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering

1997-11-01

385

Thermal analysis of magnesium reactions with nitrogen/oxygen gas mixtures.  

PubMed

The thermal behavior and kinetic parameters of magnesium powder subjected to a nitrogen-rich atmosphere was investigated in thermogravimetric (TG) and differential scanning calorimeter (DSC) experiments with oxygen/nitrogen mixtures heated at rates of 5, 10, 15, and 20 °C/min. At higher temperature increase rates, the observed oxidation or nitridation steps shifted toward higher temperatures. The comparison of mass gain and heat of reaction in different nitrogen concentrations is helpful in interpreting the inerting effect of nitrogen on magnesium powder explosion in closed vessels. Activation energies for oxidation in air calculated by the Kissinger-Akahira-Sunose (KAS) method are generally consistent with previously published reports, but the method was not successful for the entire nitridation process. The change of activation energy with temperature was related to protective properties of the corresponding coating layer at particle surfaces. Two main coating layer growth processes were found in magnesium oxidation and nitridation using a modified Dreizin method which was also employed to determine activation energy for both magnesium oxidation and nitridation. For magnesium powder oxidation, activation energy calculated by the Dreizin method was close to that by KAS. Variation in activation energies was a function of different mechanisms inherent in the two methods. PMID:23846120

Chunmiao, Yuan; Lifu, Yu; Chang, Li; Gang, Li; Shengjun, Zhong

2013-09-15

386

Fission Xenon on Mars  

NASA Technical Reports Server (NTRS)

Fission Xe components due to Pu-244 decay in the early history of Mars have been identified in nakhlites; as in the case of ALH84001 and Chassigny the fission gas was assimilated into indigenous solar-type Xe. Additional information is contained in the original extended abstract.

Mathew, K. J.; Marti, K.; Marty, B.

2002-01-01

387

Multi-quantum excitation in optically pumped alkali atom: rare gas mixtures  

NASA Astrophysics Data System (ADS)

Diode-pumped alkali laser (DPAL) technology offers a means of achieving high-energy gas laser output through optical pumping of the D-lines of Cs, Rb, and K. The exciplex effect, based on weak attractive forces between alkali atoms and polarizable rare gas atoms (Ar, Kr, Xe), provides an alternative approach via broadband excitation of exciplex precursors (XPAL). In XPAL configurations, we have observed multi-quantum excitation within the alkali manifolds which result in infrared emission lines between 1 and 4 ?m. The observed excited states include the 42FJ states of both Cs and Rb, which are well above the two-photon energy of the excitation laser in each case. We have observed fluorescence from multi-quantum states for excitation wavelengths throughout the exciplex absorption bands of Cs-Ar, Cs-Kr, and Cs-Xe. The intensity scaling is roughly first-order or less in both pump power and alkali concentration, suggesting a collisional energy pooling excitation mechanism. Collisional up-pumping appears to present a parasitic loss term for optically pumped atomic systems at high intensities, however there may also be excitation of other lasing transitions at infrared wavelengths.

Galbally-Kinney, K. L.; Rawlins, W. T.; Davis, S. J.

2014-03-01

388

Combustion of ultrafine coal/water mixtures and their application in gas turbines: Final report  

SciTech Connect

The feasibility of using coal-water fuels (CWF) in gas turbine combustors has been demonstrated in recent pilot plant experiments. The demands of burning coal-water fuels with high flame stability, complete combustion, low NO/sub x/ emission and a resulting fly ash particle size that will not erode turbine blades represent a significant challenge to combustion scientists and engineers. The satisfactory solution of these problems requires that the variation of the structure of CWF flames, i.e., the fields of flow, temperature and chemical species concentration in the flame, with operating conditions is known. Detailed in-flame measurements are difficult at elevated pressures and it has been proposed to carry out such experiments at atmospheric pressure and interpret the data by means of models for gas turbine combustor conditions. The research was carried out in five sequential tasks: cold flow studies; studies of conventional fine-grind CWF; combustion studies with ultrafine CWF fuel; reduction of NO/sub x/ emission by staged combustion; and data interpretation-ignition and radiation aspects. 37 refs., 61 figs., 9 tabs.

Toqan, M.A.; Srinivasachar, S.; Staudt, J.; Varela, F.; Beer, J.M.

1987-10-01

389

Reduced xenon diffusion for quantitative lung studythe role of SF6  

E-print Network

, sulfur hexafluoride (SF6), on 129 Xe NMR and diffusion. We found that the contribution of SF6 to 129 Xe T measurements in human alveoli using time-dependent gas diffusion NMR. KEYWORDS: xenon; diffusion; sulfur hexafluoride; restricted diffusion; pulsed gradient spin echo, PGSE; gas- diffusion NMR INTRODUCTION Following

Walsworth, Ronald L.

390

Determination of percent composition of a mixture analyzed by gas chromatography. Comparison of a helium pulsed-discharge photoionization detector with a flame ionization detector.  

PubMed

We present the results of a study of percent composition for a mixture which has been separated by gas chromatography and analyzed using helium pulsed-discharge photoionization detection (He-PDPID) and flame ionization detection (FID). FID has long been the means by which the percent composition of a hydrocarbon mixture has been determined since it has been previously established as a "carbon counting device". However, in this study we present results which show that He-PDPID is more accurate in determining the percent composition of a hydrocarbon mixture and, because it is a universal detection method and can detect compounds that FID cannot, it is also more effective for determining the percent composition of mixtures containing organic compounds with a variety of other functional groups. PMID:11403470

Dojahn, J G; Wentworth, W E; Deming, S N; Stearns, S D

2001-05-11

391

NATURE OF UNRESOLVED COMPLEX MIXTURE IN SIZE-DISTRIBUTED EMISSIONS FROM RESIDENTIAL WOOD COMBUSTION AS MEASURED BY THERMAL DESORPTION-GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

In this study, the unresolved complex mixture (UCM) in size resolved fine aerosol emissions from residential wood combustion (RWC) is examined. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorbtion/gas chroma...

392

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

E-print Network

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

Bristol, University of

393

Linear-to-Volcanic Response in a Self-Organizing Driven Fluid Mixture by an Interacting Lattice Gas Computer Simulation  

NASA Astrophysics Data System (ADS)

A computer simulation model is used to study the transport, flow, and self-organizing morphology in a multi-component fluid mixture. We consider a mixture of two immiscible components (A, B) driven by a hydrostatic pressure bias from a source (reservoir) at the bottom on a cubic lattice. Mobile particles (A, B - representing heavier gas hydrate/sediment particles and fluid) in equal number are distributed randomly on half of the lattice sites initially where a site cannot be occupied by more than one particle. The empty (pore) sites can act as a component of an effective medium. A set of interactions among these constituents is considered in addition to excluded volume hard-core interaction. The hydrostatic pressure bias (H) is implemented probabilistically to drive particles (A, B) against gravity. We use the Metropolis algorithm to move these particles stochastically. Periodic boundary conditions are used along the transverse directions while the longitudinal ends (top and bottom) are open. Thus, particles can escape from the top or bottom; however, they can enter the lattice only from the source at the bottom in this model. The probability of release of constituents (A, B) depend on their current relative concentrations in the lattice. Particles flow, re-distribute, and their concentrations change as the simulation proceeds. The flux rate of particle flow becomes constant and the morphology become stable in the long time steady-state limit. We observe a variety of self-organized structures, which exhibit dense phase at the bottom and dilute (gaseous) phase on the top with a bi-continuous phase in between. The flux rate (j) shows linear response at low hydrostatic bias but is different for constituents (A, B) with different molecular weight. The response becomes non-linear in high-bias regime; there it diverges (essentially erupts) for higher molecular weight components while it decreases for the lighter component.

Pandey, R. B.; Gettrust, J. F.

2005-05-01

394

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, July 1--September 30, 1995  

SciTech Connect

Mechanistic and kinetic studies of methanol and ethanol coupling reactions on Cs/Cu/ZnO and Cu/ZnO/MnO catalysts using isotopically-labeled compounds have confirmed that coupling reactions proceed via intermediate dehydrogenation of alcohols to aldehydes. Ethanol coupling reactions are much faster than those of methanol because ethanol forms a more thermodynamically favored intermediate (acetaldehyde), with aldol condensation pathways kinetically available for chain growth. Cs decreases the rate of formation of aldehydes in alcohol dehydrogenation reaction and inhibits the undesired conversion of methanol and ethanol to synthesis gas (CO/H{sub 2}). Construction and start-up of the Catalytic Microreactor Unit (CMRU) for high pressure isobutanol synthesis studies have been completed. Initial certification runs have reproduced catalytic CO conversion rates on a standard APCI material (Cs/Cu/ZnO/Al{sub 2}O{sub 3}). Condensation of higher alcohols in the transfer lines appears to be responsible for the observed low apparent selectivity to higher alcohols. The design and construction of the Temperature-Programmed Surface Reaction (TPSR) Unit for the study of the adsorption and reaction properties of alcohols and other oxygenates on isobutanol, synthesis catalysts and components is complete. The reduction of CuO powder and of a Cs/Cu/ZnO catalyst were used to certify the apparatus before proceeding with alcohol adsorption and reaction studies.

Eglesia, E.

1995-10-24

395

Discrete model of gas-free spin combustion of a powder mixture  

NASA Astrophysics Data System (ADS)

We propose a discrete model of gas-free combustion of a cylindrical sample which reproduces in detail a spin combustion mode. It is shown that a spin combustion, in its classical sense as a continuous spiral motion of heat release zones on the surface of the sample, does not exist. Such a concept has arisen due to the misinterpretation of the experimental data. This study shows that in fact a spinlike combustion is realized, at which two energy release zones appear on the lateral surface of the sample and propagate circumferentially in the opposite directions. After some time two new heat release zones are formed on the next layer of the cylinder surface and make the same counter-circular motion. This process continues periodically and from a certain angle it looks like a spiral movement of the luminous zone along the lateral surface of the sample. The model shows that on approaching the combustion limit the process becomes more complicated and the spinlike combustion mode shifts to a more complex mode with multiple zones of heat release moving in different directions along the lateral surface. It is shown that the spin combustion mode appears due to asymmetry of initial conditions and always transforms into a layer-by-layer combustion mode with time.

Klimenok, Kirill L.; Rashkovskiy, Sergey A.

2015-01-01

396

Theoretical study of xenon adsorption in UO2 nanoporous matrices.  

PubMed

We present a theoretical study of xenon incorporation in UO2 nanocavities, by means of Grand Canonical Monte Carlo calculations based on semi-empirical potentials. We first characterize the reconstruction of the matrix around an empty cavity which leads to a stoechiometry change from UO2 to UO in this region. Then, we determine xenon adsorption isotherms which exhibit an abrupt transition from a dilute phase to a dense one and an increase in the density of the latter phase as a function of temperature. This last result is attributed to a vibrational entropy effect by means of a mean field analysis. Finally, the pressure calculation inside the bubble proves the limitations of the usual mesoscopic models based on gas state behaviour. PMID:25388362

Colbert, Mehdi; Tréglia, Guy; Ribeiro, Fabienne

2014-12-01

397

Theoretical study of xenon adsorption in UO2 nanoporous matrices  

NASA Astrophysics Data System (ADS)

We present a theoretical study of xenon incorporation in UO2 nanocavities, by means of Grand Canonical Monte Carlo calculations based on semi-empirical potentials. We first characterize the reconstruction of the matrix around an empty cavity which leads to a stoechiometry change from UO2 to UO in this region. Then, we determine xenon adsorption isotherms which exhibit an abrupt transition from a dilute phase to a dense one and an increase in the density of the latter phase as a function of temperature. This last result is attributed to a vibrational entropy effect by means of a mean field analysis. Finally, the pressure calculation inside the bubble proves the limitations of the usual mesoscopic models based on gas state behaviour.

Colbert, Mehdi; Tréglia, Guy; Ribeiro, Fabienne

2014-12-01

398

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

399

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

400

An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in xenon dark matter detectors  

NASA Astrophysics Data System (ADS)

The XENON dark matter experiment aims to detect hypothetical weakly interacting massive particles (WIMPs) scattering off nuclei within its liquid xenon (LXe) target. The trace 85Kr in the xenon target undergoes beta-decay with a 687 keV end point and 10.8 year halflife, which contributes background events and limits the sensitivity of the experiment. In order to achieve the desired sensitivity, the contamination by krypton is reduced to the part per trillion (ppt) level by cryogenic distillation. The conventional methods are not well suited for measuring the krypton contamination at such a low level. In this work, we have developed an atom trap trace analysis (ATTA) device to detect the ultra-low krypton concentration in the xenon target. This project was proposed to the National Science Foundation (NSF) as a Major Research Instrumentation (MRI) development [Aprile and Zelevinsky, 2009] and is funded by NSF and Columbia University. The ATTA method, originally developed at Argonne National Laboratory, uses standard laser cooling and trapping techniques, and counts single trapped atoms. Since the isotopic abundance of 85Kr in nature is 1.5 x 10-11, the 85Kr/Xe level is expected to be ˜10-23, which is beyond the capability of our method. Thus we detect the most abundant (57%) isotope 84Kr, and infer the 85Kr contamination from their known abundances. To avoid contamination by krypton, the setup is tested and optimized with 40 Ar which has a similar cooling wavelength to 84Kr. Two main challenges in this experiment are to obtain a trapping efficiency high enough to detect krypton impurities at the ppt level, and to achieve the resolution to discriminate single atoms. The device is specially designed and adjusted to meet these challenges. After achieving these criteria with argon gas, we precisely characterize the efficiency of the system using Kr-Xe mixtures with known ratios, and find that ˜90 minutes are required to trap one 84Kr atom at the 1-ppt Kr/Xe contamination. This thesis describes the design, construction, and experimental results of the ATTA project at Columbia University.

Yoon, Tae Hyun

401

Inference and analysis of xenon outflow curves under multi-pulse injection in two-dimensional chromatography.  

PubMed

Multidimensional gas chromatography is widely applied to atmospheric xenon monitoring for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). To improve the capability for xenon sampling from the atmosphere, sampling techniques have been investigated in detail. The sampling techniques are designed by xenon outflow curves which are influenced by many factors, and the injecting condition is one of the key factors that could influence the xenon outflow curves. In this paper, the xenon outflow curves of single-pulse injection in two-dimensional gas chromatography has been tested and fitted as a function of exponential modified Gaussian distribution. An inference formula of the xenon outflow curve for six-pulse injection is derived, and the inference formula is also tested to compare with its fitting formula of the xenon outflow curve. As a result, the curves of both the one-pulse and six-pulse injections obey the exponential modified Gaussian distribution when the temperature of the activated carbon column's temperature is 26°C and the flow rate of the carrier gas is 35.6mLmin(-1). The retention time of the xenon peak for one-pulse injection is 215min, and the peak width is 138min. For the six-pulse injection, however, the retention time is delayed to 255min, and the peak width broadens to 222min. According to the inferred formula of the xenon outflow curve for the six-pulse injection, the inferred retention time is 243min, the relative deviation of the retention time is 4.7%, and the inferred peak width is 225min, with a relative deviation of 1.3%. PMID:24007686

Shu-Jiang, Liu; Zhan-Ying, Chen; Yin-Zhong, Chang; Shi-Lian, Wang; Qi, Li; Yuan-Qing, Fan

2013-10-11

402

A new method for sustained generation of ultra-pure nitric oxide-containing gas mixtures via controlled UVA-photolysis of nitrite solutions.  

PubMed

Exogenous gaseous nitric oxide (gNO) is an FDA approved drug for treatment of a variety of human pathologies like Persistent Pulmonary Hypertension in neonates and premature babies, skin lesions and fungal dermatophyte infections. Substantial disadvantages of current gNO-based therapies are the high therapy costs, high storage costs of the gas cylinders, and the rapid contamination of compressed NO gases with various decomposition products. Here we describe a new, very simple, and inexpensive photolytic generator of uncontaminated NO-containing gas mixtures at therapeutic concentrations. The new method bases on UVA-induced and redox-assisted decomposition of nitrite ions in aqueous solutions. NO formation via UVA-induced photolysis of nitrite is accompanied by an OH radical-dependent production of NO(2) that beside its toxic character additionally strongly reduces the NO yield by consuming NO in its reaction to N(2)O(3). During the UVA-induced photodecomposition process both, inhibition of NO(2) formation or NO(2) depletion by antioxidants hinders the NO-consuming reaction with NO(2) and ensured a maximal purity and maximal yield of NO-containing gas mixtures. Therefore, NO-containing gas mixtures generated by the described method are suitable for medical applications like inhalation or gassing of chronic non-healing wounds. Control of temperature, UVA intensity and composition of the reaction mixture allows facile control over the final NO level in the carrier gas over a wide concentration range. We demonstrate the sustained and stable release of NO over a wide dynamic range (10-5000 ppm NO) for many hours. The method avoids contamination-prone long time storage of NO gas. As such, it appears particularly relevant for applications involving the additional presence of oxygen (e.g. inhalation). PMID:20713167

Opländer, Christian; Baschin, Marcel; van Faassen, Ernst E; Born, Matthias; Möller, Manfred; Pallua, Norbert; Suschek, Christoph V

2010-12-15

403

Aqueous solubility calculation for petroleum mixtures in soil using comprehensive two-dimensional gas chromatography analysis data.  

PubMed

An assessment of aqueous solubility (leaching potential) of soil contaminations with petroleum hydrocarbons (TPH) is important in the context of the evaluation of (migration) risks and soil/groundwater remediation. Field measurements using monitoring wells often overestimate real TPH concentrations in case of presence of pure oil in the screened interval of the well. This paper presents a method to calculate TPH equilibrium concentrations in groundwater using soil analysis by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography (HPLC-GCXGC). The oil in the soil sample is divided into 79 defined hydrocarbon fractions on two GCXGC color plots. To each of these fractions a representative water solubility is assigned. Overall equilibrium water solubility of the non-aqueous phase liquid (NAPL) present in the sample and the water phase's chemical composition (in terms of the 79 fractions defined) are then calculated using Raoult's law. The calculation method was validated using soil spiked with 13 different TPH mixtures and 1 field-contaminated soil. Measured water solubilities using a column recirculation equilibration experiment agreed well to calculated equilibrium concentrations and water phase TPH composition. PMID:18775542

Mao, Debin; Lookman, Richard; Van De Weghe, Hendrik; Vanermen, Guido; De Brucker, Nicole; Diels, Ludo

2009-04-01

404

Greenhouse gas production in mixtures of soil with composted and noncomposted biochars is governed by char-associated organic compounds.  

PubMed

Biochar application to soil has the potential to increase soil productivity while reducing anthropogenic greenhouse gas (GHG) emissions to the atmosphere. However, techniques for conditioning this material for maximizing its effects as a soil amendment require elucidation. We examined changes of organic matter associated with two biochars after 175 d of composting and the resulting effects on GHG emissions during a 150-d incubation period. Composting decreased the amount of organic compounds that could be thermally released from the biochars and affected their molecular nature. These thermally desorbable organic compounds from initial biochars likely stimulated the oxidation of CH and inhibited the production of NO in soil-biochar mixtures. However, these reductions of GHG emissions disappeared together with thermally desorbable organic compounds after the composting of chars. Instead, addition of composted gasification coke and charcoal stimulated the formation of CH and increased NO emissions by 45 to 56%. Nitrous oxide emissions equaled 20% of the total amount of N added with composted biochars, suggesting that organic compounds and N sorbed by the chars during composting fueled GHG production. The transient nature of the suppression of CH and NO production challenges the long-term GHG mitigation potential of biochar in soil. PMID:25602826

Borchard, Nils; Spokas, Kurt; Prost, Katharina; Siemens, Jan

2014-05-01

405

Understanding the amorphous-to-microcrystalline silicon transition in SiF4/H2/Ar gas mixtures  

NASA Astrophysics Data System (ADS)

We report on the growth of microcrystalline silicon films from the dissociation of SiF4/H2/Ar gas mixtures. For this growth chemistry, the formation of HF molecules provides a clear signature of the amorphous to microcrystalline growth transition. Depositing films from silicon tetrafluoride requires the removal of F produced by SiF4 dissociation, and this removal is promoted by the addition of H2 which strongly reacts with F to form HF molecules. At low H2 flow rates, the films grow amorphous as all the available hydrogen is consumed to form HF. Above a critical flow rate, corresponding to the full removal of F, microcrystalline films are produced as there is an excess of atomic hydrogen in the plasma. A simple yet accurate phenomenological model is proposed to explain the SiF4/H2 plasma chemistry in accordance with experimental data. This model provides some rules of thumb to achieve high deposition rates for microcrystalline silicon, namely, that increased RF power must be balanced by an increased H2 flow rate.

Dornstetter, Jean-Christophe; Bruneau, Bastien; Bulkin, Pavel; Johnson, Erik V.; Roca i Cabarrocas, Pere

2014-06-01

406

Understanding the amorphous-to-microcrystalline silicon transition in SiF4/H2/Ar gas mixtures.  

PubMed

We report on the growth of microcrystalline silicon films from the dissociation of SiF4/H2/Ar gas mixtures. For this growth chemistry, the formation of HF molecules provides a clear signature of the amorphous to microcrystalline growth transition. Depositing films from silicon tetrafluoride requires the removal of F produced by SiF4 dissociation, and this removal is promoted by the addition of H2 which strongly reacts with F to form HF molecules. At low H2 flow rates, the films grow amorphous as all the available hydrogen is consumed to form HF. Above a critical flow rate, corresponding to the full removal of F, microcrystalline films are produced as there is an excess of atomic hydrogen in the plasma. A simple yet accurate phenomenological model is proposed to explain the SiF4/H2 plasma chemistry in accordance with experimental data. This model provides some rules of thumb to achieve high deposition rates for microcrystalline silicon, namely, that increased RF power must be balanced by an increased H2 flow rate. PMID:24952559

Dornstetter, Jean-Christophe; Bruneau, Bastien; Bulkin, Pavel; Johnson, Erik V; Roca i Cabarrocas, Pere

2014-06-21

407

Time stability of liquid xenon photoionization detectors  

Microsoft Academic Search

We measured the collected charges, the energy resolution and their time stability using an ionization chamber filled with liquid xenon doped with trimethylamine (TMA) as photoionization molecules. When liquid xenon was doped with a low concentration of TMA purified at ?110°C, the chamber was operated stably at ?110°C for about 50 h.

H. Okada; T. Doke; K. Hasuike; J. Kikuchi; K. Masuda; M. Shinoda; T. Takahashi; K. Terasawa

1996-01-01

408

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

409

Prospects for Barium Tagging in Gaseous Xenon  

SciTech Connect

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. It is clear from this study that electrospray is a convenient mechanism for producing Ba++ is gas at atmospheric pressure. It is likely that the source will perform just as effectively at higher pressures. Even though the source region has water vapour and methanol vapour at the 0.3% level, there is no evidence for molecular formation. The use of TEA offers an effective method to achieve the charge state conversion. The overall design of the ion extraction from high pressure to vacuum is very similar to the scheme proposed for the final detector and this appears to work well although the efficiency is not yet determined.

Sinclair, D.; /Carleton U. /TRIUMF; Rollin, E.; /Carleton U.; Smith, J.; /Carleton U.; Mommers, A.; /Ottawa U.; Ackerman, N.; /SLAC; Aharmim, B.; /Laurentian U.; Auger, M.; /Bern U., LHEP; Barbeau, P.S.; /Stanford U., Phys. Dept.; Benitez-Medina, C.; /Colorado State U.; Breidenbach, M.; /SLAC; Burenkov, A.; /Moscow, ITEP; Cook, S.; /SLAC; Coppens, A.; /Carleton U.; Daniels, T.; /Massachusetts U., Amherst; DeVoe, R.; /Stanford U., Phys. Dept.; Dobi, A.; /Maryland U.; Dolinski, M.J.; Donato, K.; /Stanford U., Phys. Dept.; Fairbank, W., Jr.; /Colorado State U.; Farine, J.; /Laurentian U.; Giroux, G.; /Bern U., LHEP /Carleton U. /Stanford U., Phys. Dept. /Carleton U. /Laurentian U. /Carleton U. /SLAC /Indiana U. /Indiana U., CEEM /Korea U. /Stanford U., Phys. Dept. /SLAC /Alabama U. /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Stanford U., Phys. Dept. /Alabama U. /Massachusetts U., Amherst /SLAC /Alabama U. /SLAC /Maryland U. /Moscow, ITEP /Stanford U., Phys. Dept. /Maryland U. /Bern U., LHEP /Laurentian U. /SLAC /Maryland U.

2012-05-03

410

A new developed velocity of sound measurement device for characterization of multi-component gas mixtures under elevated temperatures and pressures  

NASA Astrophysics Data System (ADS)

Inline process control by measurement of velocity of sound of fluids is a direct and comprehensive technique [J. D. N. Cheeke and Z. Wang, "Acoustic wave gas sensors," Sens. Actuators B 59, 146-153 (1999); J. W. Grate, S. J. Martin, and R. M. White, "Acoustic wave microsensors," Anal. Chem. 65, 1868 (1993)]. Depending on the varying conditions of measuring fluid(s), temperatures and pressures, it is a challenging task to find the best possible acoustic setup. Taking this background into account, a velocity of sound measurement device for temperatures up to 475 K and pressures up to 24 MPa was designed and assembled that is to be used for testing different resonator types. Two bulk acoustic wave resonators out of the commonly used lead zirconatetitanate compound (PZT) were tested at different test fluids under temperatures up to 423.15 K and pressures up to 24 MPa [S. Gebhardt, L. Seffner, F. Schlenkirch, and A. Schönecker, "PZT thick films for sensor and actuator applications," J. Eur. Ceram. Soc. 27, 4177-4180 (2007)]. Initially the pure gases methane, ethane, carbon dioxide, nitrogen, and helium were measured, followed by multi-component gas mixtures. Beside methane-based binary and ternary gas mixtures, a quaternary gas mixture comprising methane, ethane, carbon dioxide, and helium was analyzed. Results for all measurement fluids in a broad temperature and pressure range show a relative deviation to theoretical values derived from GERG-2008 smaller than 0.5%.

Seibel, C.; Suedmeyer, J.; Fieback, T. M.

2014-07-01

411

Performance of a cryogenic system prototype for the XENON1T detector  

NASA Astrophysics Data System (ADS)

We have developed an efficient cryogenic system with heat exchange and associated gas purification system as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 tons of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in series, a heat exchange efficiency better than 96% has been measured.

Aprile, E.; Budnik, R.; Choi, B.; Contreras, H. A.; Giboni, K. L.; Goetzke, L. W.; Lang, R. F.; Lim, K. E.; Melgarejo, A. J.; Plante, G.; Rizzo, A.; Shagin, P.

2012-10-01

412

Performance of a cryogenic system prototype for the XENON1T Detector  

E-print Network

We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured.

Aprile, Elena; Choi, Bin; Contreras, Hugo; Giboni, Karl; Goetzke, Luke; Lang, Rafael; Lim, Kyungeun; melgarejo, Antonio; Shagin, Petr

2012-01-01

413

Extreme confinement of xenon by cryptophane-111 in the solid state.  

PubMed

Solids that sorb, capture and/or store the heavier noble gases are of interest because of their potential for transformative rare gas separation/production, storage, or recovery technologies. Herein, we report the isolation, crystal structures, and thermal stabilities of a series of xenon and krypton clathrates of (±)-cryptophane-111 (111). One trigonal crystal form, Xe@111?y(solvent), is exceptionally stable, retaining xenon at temperatures of up to about 300?°C. The high kinetic stability is attributable not only to the high xenon affinity and cage-like nature of the host, but also to the crystal packing of the clathrate, wherein each window of the molecular container is blocked by the bridges of adjacent containers, effectively imprisoning the noble gas in the solid state. The results highlight the potential of discrete molecule materials exhibiting intrinsic microcavities or zero-dimensional pores. PMID:25504739

Joseph, Akil I; Lapidus, Saul H; Kane, Christopher M; Holman, K Travis

2015-01-26

414

Performance of a cryogenic system prototype for the XENON1T Detector  

E-print Network

We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured.

Elena Aprile; Ran Budnik; Bin Choi; Hugo Contreras; Karl Giboni; Luke Goetzke; Rafael Lang; Kyungeun Lim; Antonio melgarejo; Petr Shagin

2012-08-29

415

Coupled gas flow/solid dynamics model for predicting the formation of fracture patterns in gas well simulation experiments. [Propellant mixture used instead of explosives to fracture rock surrounding borehole  

SciTech Connect

A two-dimensional finite element model for predicting fracture patterns obtained in high energy gas fracture experiments is presented. In these experiments, a mixture of propellants is used instead of explosives to fracture the rock surrounding the borehole. The propellant mixture is chosen to tailor the pressure pulse so that multiple fractures emanate from the borehole. The model allows the fracture pattern and pressure pulse to be calculated for different combinations of propellant mixture, in situ stress conditions, and rock properties. The model calculates the amount of gas generated by the burning propellants using a burn rate given by a power law in pressure. By assuming that the gas behaves as a perfect gas and that the flow down the fractures is isothermal, the loss of gas from the borehole due to flow down the cracks is accounted for. The flow of gas down the cracks is included in an approximate manner by assuming self-similar pressure profiles along the fractures. Numerical examples are presented and compared to three different full-scale experiments. Results show a good correlation with the experimental data over a wide variety of test parameters. 9 reference, 10 figures, 3 tables.

Taylor, L.M.; Swenson, D.V.; Cooper, P.W.

1984-07-01

416

Kinetic boundary layers in gas mixtures: Systems described by nonlinearly coupled kinetic and hydrodynamic equations and applications to droplet condensation and evaporation  

SciTech Connect

The authors consider a mixture of heavy vapor molecules and a light carrier gas surrounding a liquid droplet. The vapor is described by a variant of the Klein-Kramers equation; the gas is described by the Navier-Stokes equations; the droplet acts as a heat source due to the released heat of condensation. The exchange of momentum and energy between the constituents of the mixture is taken into account by force terms in the kinetic equation and source terms in the Navier-Stokes equations. These are chosen to obtain maximal agreement with the irreversible thermodynamics of a gas mixture. The structure of the kinetic boundary layer around the sphere is determined from the self-consistent solution of this set of coupled equations with appropriate boundary conditions at the surface of the sphere. The kinetic equation is rewritten as a set of coupled moment equations. A complete set of solutions of these moment equations is constructed by numerical integration inward from the region far away from the droplet, where the background inhomogeneities are small. A technique developed earlier is used to deal with the numerical instability of the moment equations. The solutions obtained for given temperature and pressure profiles in the gas are then combined linearly such that they obey the boundary conditions at the droplet surface; from this solution source terms for the Navier-Stokes equation of the gas are constructed and used to determine improved temperature and pressure profiles for the background gas. For not too large temperature differneces between the droplet and the gas at infinity, self-consistency is reached after a few iterations. The method is applied to the condensation of droplets from a supersaturated vapor as well as to strong evaporation of droplets under the influence of an external heat source, where corrections of up to 40% are obtained.

Widder, M.E.; Titulaer, U.M. (Johannes-Kepler-Universitaet Linz (Austria))

1993-03-01

417

Gamma background studies for the XENON experiment using a High Purity Germanium Detector  

NASA Astrophysics Data System (ADS)

The XENON Dark Matter Experiment, deployed at the Gran Sasso National Laboratory in Italy on March 2006, is a liquid noble gas detector designed to directly detect dark matter. The detector uses a dual-phase (gas/liquid) Xenon target to search for nuclear recoils associated with nucleus-WIMP interactions. Due to the high sensitivity needed in such an experiment, it is vital to not only reduce the background but to also understand the remaining background so as to aid in the understanding of the data as well as to facilitate upgrades beyond the early Research and Development phases. Many of the components of the XENON10 detector have been screened using a High Purity Germanium Detector known as the GATOR detector. Full analysis of the screening data requires Monte Carlo simulations of the GATOR detector and the sample. Results from this screening will be presented. Using the information obtained from the screening operation, Monte Carlo simulations of the XENON10 electron recoil background will be examined and compared to the actual detector data. The success of this simulation to data comparison indicates that we have a good understanding of the XENON10 gamma background and will be able to make more informed decisions regarding the next stage of detector development. This type of analysis has aided in the selection and design of many of the materials and components being incorporated into the new XENON100 detector, the next generation detector which will be capable of improving the limit set by XENON10 by at least an order of magnitude. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http:/ /www.uflib.ufl.edu/etd.html)

Angle, Jesse Isaac

418

Magnetization transfer from laser-polarized xenon to protons located in the hydrophobic cavity of the wheat nonspecific lipid transfer protein  

PubMed Central

Nonspecific lipid transfer protein from wheat is studied by liquid-state NMR in the presence of xenon. The gas–protein interaction is indicated by the dependence of the protein proton chemical shifts on the xenon pressure and formally confirmed by the first observation of magnetization transfer from laser-polarized xenon to the protein protons. Twenty-six heteronuclear nOes have allowed the characterization of four interaction sites inside the wheat ns-LTP cavity. Their locations are in agreement with the variations of the chemical shifts under xenon pressure and with solvation simulations. The richness of the information obtained by the noble gas with a nuclear polarization multiplied by ?12,000 makes this approach based on dipolar cross-relaxation with laser-polarized xenon promising for probing protein hydrophobic pockets at ambient pressure. PMID:11274467

Landon, Céline; Berthault, Patrick; Vovelle, Françoise; Desvaux, Hervé

2001-01-01

419

Viscosity and pVT-Second Virial Coefficient of Binary Noble-Globular Gas and Globular-Globular Gas Mixtures Calculated by Means of an Isotropic Temperature-Dependent Potential  

NASA Astrophysics Data System (ADS)

This work presents results of an extension of our earlier studies of the transport and equilibrium properties of pure heavy globular gases. It demonstrates a simple and reliable procedure for estimating the equilibrium and transport properties of their mixtures using the pure gas potentials of interaction when there are no available experimental data. Here we consider binary gas mixtures of globular gases between themselves and with the noble gases as well. The gases involved are: BF3, CH4, CF4, SiF4, SiCl4, CCl4, SF6, MoF6, WF6, UF6, C(CH3)4, Si(CH3)4, Ar, Kr, and Xe. The calculations were performed by means of the so called isotropic temperature-dependent potential (ITDP) introduced by us earlier and applied to some binary mixtures (CH4-CF4, CH4-SF6, CF4-SF6). The CH4-CH4 and noble gases potentials of interactions have been determined in a (n-6) Lennard-Jones shape in the temperature range 200-1000 K by fitting a large number of viscosity and pVT-second virial coefficient data measured by different authors with different experimental techniques. The ITDP parameters of molecular gases were taken from the tables we have determined and published earlier [L. Zarkova and U. Hohm, J. Phys. Chem. Ref. Data 31, 183 (2002)]. Simple combination rules allow us to take into account the influence of the temperature on the thermophysical properties of the binary gas mixtures containing heavy globular molecules. Tables with potential parameters of equal and unequal particles and properties of the equimolar mixtures are given for all mixtures in the temperature range 200-900 (1000) K. The deviations between experimental and calculated viscosity and second virial coefficient data of some more examined mixtures permit to evaluate the quality of the proposed approach.

Zarkova, L.; Hohm, U.; Damyanova, M.

2003-12-01

420

High-pressure xenon detector development at Constellation Technology Corporation  

NASA Astrophysics Data System (ADS)

Xenon-filled ionization detectors, due to their high atomic number fill gas ( Z=54), moderate densities (˜0.3-0.5 g/cm 3) and good energy resolution (2-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and germanium detectors. Until recently, difficulties with obtaining sufficient xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990s, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Current applications for Constellation's detectors are principally in the area of defense (Unmanned Aerial Vehicles and Advanced Spectroscopic Portals), but as awareness of this technology grows, it will surely find applications in a much expanded range of fields.

Austin, Robert A.

2007-08-01

421

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield  

NASA Astrophysics Data System (ADS)

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume (~18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts (~1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving ~6.5 kJ L-1 atm-1 per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O2 : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O2(a1?g) and O2(b1?g+), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O2(a1?g) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value ~3% for W ~ 1.0 kJ L-1 atm-1 is in agreement with the theoretical estimate. Theoretical calculations performed for W ~ 6.5 kJ L-1 atm-1 at a fixed temperature show that the singlet-oxygen yield may be ~20%, which is higher than the value required to achieve the lasing threshold in an oxygen—iodine laser at room temperature.

Vagin, Nikolai P.; Ionin, Andrei A.; Klimachev, Yu M.; Kotkov, A. A.; Kochetov, Igor'V.; Napartovich, A. P.; Podmar'kov, Yu P.; Seleznev, L. V.; Sinitsyn, D. V.; Frolov, M. P.; Hager, G. D.; Yuryshev, Nikolai N.

2004-09-01

422

Development of a coulometric method for assessing the concentration of ambient levels of CO2/air in compressed-gas mixtures  

SciTech Connect

The understanding of global 'greenhouse' issues as they relate to CO2 in the atmosphere is a current environmental concern. At the National Institute of Standards and Technology there is a continuous search for methods of analysis that yield results that are traceable to fundamental quantities. The coulometric method presented here is a reliable method for the direct analysis of CO2/air cylinder gas mixtures. It is based on Faraday's laws of electrolysis and therefore no external standardization is required. A series of CO2/air cylinder gas mixtures ranging in concentration from 300 to 375 micromol/mol (ppm) were analyzed and the results compared to those results obtained by non-dispersive infrared (NDIR) analysis with traceability to gravimetric standards. The coulometric method is rapid, sensitive, precise, and with the proper experimental controls, will yield accurate results.

Mitchell, G.D.; Bell, A.A.

1991-01-01

423

Plasma etching of sputtered Mo and MoSi2 thin films in NF3 gas mixtures  

NASA Astrophysics Data System (ADS)

Plasma etching characteristics of sputtered molybdenum and MoSi2 thin films using various NF3 gas mixtures in a planar reactor are presented. Anisotropic (vertical-to-lateral etch ratio of ˜3) edge profiles were obtained. The etch rates of Mo, MoSi2, doped poly-Si, and SiO2 were determined as a function of rf current, reactor pressure, and NF3 concentration. At 1 A and 100 mTorr in 100% NF3, etch rates of 2490, 3440, 14000, and 670 Å/min were measured for Mo, MoSi2, doped poly-Si, and SiO2, respectively. Also, the etch rate ratios of Mo, MoSi2, doped poly- Si over SiO2 were 1.5-4, 4-8, and 12-24, respectively. Diluting the NF3 plasmas with argon or helium decreased the etch rates for all the materials studied here. At 200 mTorr and 1 A, the Mo etch rate dropped from 1800 Å/min in 100% NF3 to 540 Å/min in 20% NF3/80% Ar, while the corresponding silicide etch rate decreased from 7850 to 1130 Å/min. Auger spectroscopy measurements inferred that the desorption of molybdenum products, but not the silicon ones, may be the rate-limiting step in the etching process. Furthermore, dc voltage measurements on the rf electrode indicated a higher degree of ion bombardment at low pressures (<150 mTorr) and in NF3 plasmas diluted with inert gases.

Chow, T. P.; Steckl, A. J.

1982-08-01

424

Optical and Electron Spin Resonance Studies of Xenon-Nitrogen-Helium Condensates Containing Nitrogen and Oxygen Atoms.  

PubMed

We present the first observations of excimer XeO* molecules in molecular nitrogen films surrounding xenon cores of nanoclusters. Multishell nanoclusters form upon the fast cooling of a helium jet containing small admixtures of nitrogen and xenon by cold helium vapor (T = 1.5 K). Such nanoclusters injected into superfluid helium aggregate into porous impurity-helium condensates. Passage of helium gas with admixtures through a radio frequency discharge allows the storage of high densities of radicals stabilized in impurity-helium condensates. Intense recombination of the radicals occurs during destruction of such condensates and generates excited species observable because of optical emission. Rich spectra of xenon-oxygen complexes have been detected upon destruction of xenon-nitrogen-helium condensates. A xenon environment quenches metastable N((2)D) atoms but has a much weaker effect on the luminescence of N((2)P) atoms. Electron spin resonance spectra of N((4)S) atoms trapped in xenon-nitrogen-helium condensates have been studied. High local concentrations of nitrogen atoms (up to 10(21) cm(-3)) stabilized in xenon-nitrogen nanoclusters have been revealed. PMID:25353614

Boltnev, Roman E; Bykhalo, Igor B; Krushinskaya, Irina N; Pelmenev, Alexander A; Khmelenko, Vladimir V; Mao, Shun; Meraki, Adil; Wilde, Scott C; McColgan, Patrick T; Lee, David M

2014-11-11

425

Instability of mechanical equilibrium during diffusion in a three-component gas mixture in a vertical cylinder with a circular cross section  

NASA Astrophysics Data System (ADS)

The problem of the emergence of instability of mechanical equilibrium of a three-component gas mixture during diffusion in a vertical channel with the wall impenetrable for the mass flux is considered in the case when the channel has a circular cross section. The critical Rayleigh numbers are determined, and the neutral stability lines are found in analytic form. The results are compared with experimental data.

Kosov, V. N.; Fedorenko, O. V.; Zhavrin, Yu. I.; Mukamedenkyzy, V.

2014-04-01

426

Contribution of Stark broadening to the Balmer Halpha line profile observed from barrier discharges in Ar\\/H2 gas mixtures  

Microsoft Academic Search

Results of line profile studies of the Balmer Halpha transition emitted from barrier discharges with a plane-parallel electrode configuration in an Ar\\/H2 gas mixture (90% Ar, 10% H2) at a pressure of 4 kPa are reported. Polarization and phase sensitive emission measurements are performed for various plasma layers, i.e. for different distances from dielectric surfaces limiting the discharge gap. It

H. W. Janus

2007-01-01

427

Contribution of Stark broadening to the Balmer H? line profile observed from barrier discharges in Ar\\/H2 gas mixtures  

Microsoft Academic Search

Results of line profile studies of the Balmer H? transition emitted from barrier discharges with a plane-parallel electrode configuration in an Ar\\/H2 gas mixture (90% Ar, 10% H2) at a pressure of 4 kPa are reported. Polarization and phase sensitive emission measurements are performed for various plasma layers, i.e. for different distances from dielectric surfaces limiting the discharge gap. It

H W Janus

2007-01-01

428

Fusion reactions in a plasma focus operated with 3He-D2 and 4He-D2 gas mixtures  

NASA Astrophysics Data System (ADS)

A 3 kJ plasma focus (PF) device was operated with two different gas mixtures: 3He-D2 and 4He-D2, both having He/D atomic ratios of 1 : 1. For the 3He-D2 mixture, the fusion reactions D(3He,p)4He and D(d,p)3H were measured simultaneously using CR-39 nuclear track detectors located inside a pinhole camera positioned on the forward PF axis. A double-layer arrangement of two 1000 ?m thick CR-39 detectors permitted the separate registration of protons from the D(3He,p)4He and D(d,p)3H reactions. For the 4He-D2 mixture, the D(d,p)3H protons were registered by a single CR-39 layer. Radial track density distributions were obtained for each series of experiments. For the 3He-D2 mixture, it was found that D(3He,p)4He and D(d,p)3H fusion yields were of similar magnitude, but the D(3He,p)4He fusion is concentrated close to the pinch column, whereas the D(d,p)3H fusion occurred relatively far from the pinch. The results for D(d,p)3H fusion in the 4He-D2 mixture enabled an informative comparison to bemade with the corresponding 3He-D2 data.

Springham, S. V.; Sim, T. H.; Lee, P.; Patran, A.; Rawat, R. S.; Shutler, P. M. E.; Tan, T. L.; Lee, S.

2006-04-01

429

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.degree. to 30.degree. C.

Markey, John K. (New Haven, CT)

1989-01-01

430

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

431

Effect of N{sub 2} + H{sub 2} gas mixtures in plasma nitriding on tribological properties of duplex surface treated steels  

SciTech Connect

Thermo-reactive diffusion chromizing followed by pulsed plasma nitriding were carried out on AISI 52100 and 8620 bearing steels. The chromized samples were pulse-plasma nitrided for 5 h at 500 deg. C in various N{sub 2}-H{sub 2} gas mixtures. The coated steels were characterized using scanning electron microscopy, X-ray diffraction and microhardness testing. The unlubricated wear behaviors of only chromized and duplex treated steels were investigated in ball-on-disc system tests at room temperature. X-ray diffraction patterns of the duplex treated samples containing H{sub 2} indicated the formation of dominant CrN and Cr{sub 2}N nitrides as well as the formation of Cr{sub 3}C{sub 2} and Cr{sub 7}C{sub 3} carbides. Gas mixtures in the plasma nitriding, which was performed after chromizing, have a significant influence on the wear rate of the duplex treated steels. The wear and friction tests showed that the lowest friction coefficient and wear rates were observed for the samples duplex treated in a 50%N{sub 2} +50%H{sub 2} plasma. Conversely, the lowest wear resistance was observed on the samples duplex treated in a gas mixture of 75%N{sub 2} + 25%H{sub 2}, probably due to formation of a hard and brittle layer.

Taktak, Sukru [Afyon Kocatepe University, Technical Education Faculty, Department of Metal Education, Afyonkarahisar (Turkey)], E-mail: taktak@aku.edu.tr; Gunes, Ibrahim; Ulker, Sukru; Yalcin, Yilmaz [Afyon Kocatepe University, Technical Education Faculty, Department of Metal Education, Afyonkarahisar (Turkey)

2008-12-15

432

Results from the XENON100 Dark Matter Search Experiment  

E-print Network

XENON100 is a liquid xenon time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles (WIMPs), which are candidates for the dark matter in our universe, with xenon atoms. Operated in a low-background shield at the Gran Sasso Underground Laboratory in Italy, XENON100 has reached the unprecedented background level of XENON1T detector in Hall B of the Gran Sasso Laboratory will start in late 2012.

Laura Baudis; for the XENON Collaboration

2012-03-07

433

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

434

Measurement of Xenon Viscosity as a Function of Low Temperature and Pressure  

NASA Technical Reports Server (NTRS)

The measurement of xenon gas viscosity at low temperatures (175-298 K) and low pressures (350 torr-760 torr) has been performed in support of Hall Thruster testing at NASA Lewis Research Center. The measurements were taken using the capillary flow technique. Viscosity measurements were repeatable to within 3%. The results in this paper are in agreement with data from Hanley and Childs and suggest that the data from Clarke and Smith is approximately 2% low. There are no noticeable pressure effects on xenon absolute viscosity for the pressure range from 350 torr to 760 torr.

Grisnik, Stanley P.

1998-01-01

435

Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) enables high-resolution non-invasive observation of the anatomy and function of intact organisms. However, previous MRI reporters of key biological processes tied to gene expression have been limited by the inherently low molecular sensitivity of conventional 1H MRI. This limitation could be overcome through the use of hyperpolarized nuclei, such as in the noble gas xenon, but previous reporters acting on such nuclei have been synthetic. Here, we introduce the first genetically encoded reporters for hyperpolarized 129Xe MRI. These expressible reporters are based on gas vesicles (GVs), gas-binding protein nanostructures expressed by certain buoyant microorganisms. We show that GVs are capable of chemical exchange saturation transfer interactions with xenon, which enables chemically amplified GV detection at picomolar concentrations (a 100- to 10,000-fold improvement over comparable constructs for 1H MRI). We demonstrate the use of GVs as heterologously expressed indicators of gene expression and chemically targeted exogenous labels in MRI experiments performed on living cells.

Shapiro, Mikhail G.; Ramirez, R. Matthew; Sperling, Lindsay J.; Sun, George; Sun, Jinny; Pines, Alexander; Schaffer, David V.; Bajaj, Vikram S.

2014-07-01

436

The MEG Liquid Xenon calorimeter  

NASA Astrophysics Data System (ADS)

The MEG experiment at PSI is searching for the lepton-flavour violating decay of the muon into an electron-gamma pair. It is expected to take physics data during the years 2008-2011. From the first three months of data at the end of 2008, we got an upper limit BR(?+ ? e+ + ?) ? 3.0 × 10-11 (90% C.L.). The core of the MEG experiment is an innovative gamma-ray detector, this is a large acceptance and large mass (roughly 2.2 Tons) liquid xenon volume read by photo-multiplier tubes, which is used to measure the photon energy and the position and time of its first conversion. The operation of the detector during the 2008 run will be presented together with several calibration techniques developed to monitor its stability and behaviour during experimental data taking.

Gallucci, G.

2010-04-01

437

First Results from the XENON10 Dark Matter Experiment the Gran Sasso Underground Lab  

NASA Astrophysics Data System (ADS)

We report the first results from a search for Weakly Interacting Massive Particles (WIMPs) with the XENON10 experiment operating underground at the Gran Sasso Laboratory. XENON10 is the first dual phase xenon time projection chamber (XeTPC) module realized within the XENON program. The 3D-postion sensitive detector has an active mass of 15 kg of liquid xenon, viewed by two arrays of compact photomultipliers, to measure simultaneously the scintillation and the ionization, via proportional scintillation in the gas. Background rejection on an event-by-event basis is achieved through this measurement and 3D event localization. The detector was deployed underground in Spring 2006 and mounted in its shield in Summer 2006. The experiment has been operating continuously for the past five months, with a high degree of stability and very good performance. The energy threshold is <10 keV and the background rate is <1evt/kg/keV/day. In-situ gamma and neutron calibrations have been carried out to define event selection and energy threshold for nuclear recoil candidates. Data taking continues as of this writing. A blind analysis on the latest months of data is currently being performed using only calibration data. WIMP search results are expected by early Spring 2007.

Aprile, Elena

2007-04-01

438

Electric-discharge xenon laser with weak ionization by an external source  

NASA Astrophysics Data System (ADS)

The development and testing of a laser at the IR transitions in xenon operating in the emission field of a stationary nuclear reactor are reported. Maximum energy characteristics (energy output, 0.1 J/l; efficiency - 0.1-0.2 percent of the energy input) were obtained with a mixture of Ar:Xe=100:1 at a pressure of 2 atm, with ionization by U-235 fission fragments. Laser operation at temperatures up to 650 C has been demonstrated.

Batyrbekov, G. A.; Batyrbekov, E. G.; Danilychev, V. A.; Tleuzhanov, A. B.; Khasenov, M. U.

1989-11-01

439

Cooling molten salt reactors using "gas-lift"  

NASA Astrophysics Data System (ADS)

This study briefly describes the selection of a type of two-phase flow, suitable for intensifying the natural flow of nuclear reactors with liquid fuel - cooling mixture molten salts and the description of a "Two-phase flow demonstrator" (TFD) used for experimental study of the "gas-lift" system and its influence on the support of natural convection. The measuring device and the application of the TDF device is described. The work serves as a model system for "gas-lift" (replacing the classic pump in the primary circuit) for high temperature MSR planned for hydrogen production. An experimental facility was proposed on the basis of which is currently being built an experimental loop containing the generator, separator bubbles and necessary accessories. This loop will model the removal of gaseous fission products and tritium. The cleaning of the fuel mixture of fluoride salts eliminates problems from Xenon poisoning in classical reactors.

Zitek, Pavel; Valenta, Vaclav; Klimko, Marek

2014-08-01

440

Plasma-Assisted Chemical Vapor Deposition of Titanium Oxide Films by Dielectric Barrier Discharge in TiCl4/O2/N2 Gas Mixtures  

NASA Astrophysics Data System (ADS)

Low-pressure dielectric barrier discharge (DBD) TiCl4/O2 and N2 plasmas have been used to deposit titanium oxide films at different power supply driving frequencies. A homemade large area low pressure DBD reactor was applied, characterized by the simplicity of the experimental set-up and a low consumption of feed gas and electric power, as well as being easy to operate. Atomic force microscopy, scanning electron microscopy, energy dispersive spectroscopy, and contact angle measurements have been used to characterize the deposited films. Experimental results show all deposited films are uniform and hydrophilic with a contact angle of about 15°. Compared to titanium oxide films deposited in TiCl4/O2 gas mixtures, those in TiCl4/O2/N2 gas mixtures are much more stable. The contact angle of titanium oxide films in TiCl4/O2/N2 gas mixtures with the addition of 50% N2 and 20% TiCl4 is still smaller than 20°, while that of undoped titanium oxide films is larger than 64° when they are measured after one week. The low-pressure TiCl4/O2 plasmas consist of pulsed glow-like discharges with peak widths of several microseconds, which leads to the uniform deposition of titanium oxide films. Increasing a film thickness over several hundreds of nm leads to the film's fragmentation due to the over-high film stress. Optical emission spectra (OES) of TiCl4/O2 DBD plasmas at various power supply driving frequencies are presented.

Niu, Jinhai; Zhang, Zhihui; Fan, Hongyu; Yang, Qi; Liu, Dongping; Qiu, Jieshan

2014-07-01

441

Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique.  

PubMed

In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium. PMID:25049496

Seresinhe, T; Madushika, S A C; Seresinhe, Y; Lal, P K; Orskov, E R

2012-10-01

442

Effects of Tropical High Tannin Non Legume and Low Tannin Legume Browse Mixtures on Fermentation Parameters and Methanogenesis Using Gas Production Technique  

PubMed Central

In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it’s highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium. PMID:25049496

Seresinhe, T.; Madushika, S. A. C.; Seresinhe, Y.; Lal, P. K.; Ørskov, E. R.

2012-01-01

443

Gas-chromatographic fatty-acid fingerprints and partial least squares modeling as a basis for the simultaneous determination of edible oil mixtures.  

PubMed

Partial least squares modeling and gas-chromatographic fatty-acid fingerprints are reported as a method for the simultaneous determination of cottonseed, olive, soybean and sunflower edible oil mixtures. In this work, two sets of three- and four-component combinations of oils were prepared, hydrolyzed and the obtained free fatty acids analyzed by gas chromatography (GC) without any further derivatization. The normalized percentages of the myristic (14:0), palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linoleic (18:2) and linolenic (18:3) acids were chromatographically measured in samples and used for constructing calibration matrix. The cross-validation method was used to select the number of factors and the proposed methods were validated by using two sets of synthetic oil mixture samples. The relative standard error for each oil in mixture samples was less than 10%. This approach allows determining possible adulteration in each of the four edible oils. PMID:18970097

Hajimahmoodi, M; Vander Heyden, Y; Sadeghi, N; Jannat, B; Oveisi, M R; Shahbazian, S

2005-06-15

444

Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info)  

SciTech Connect

Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.

Aerosol Dynamics Inc.,; Aerodyne Research, Inc.,; Tofwerk AG, Thun, Switzerland; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H.; Worton, David R.; Kimmel, Joel R.; Nah, Theodora; Hohaus, Thorsten; Gonin, Marc; Kroll, Jesse H.; Worsnop, Doug R.; Goldstein, Allen H.

2011-09-05

445

Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS)  

SciTech Connect

Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.

Aerosol Dynamics Inc; Aerodyne Research, Inc.,; Tofwerk AG, Thun; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H.; Worton, David R.; Kimmel, Joel R.; Nah, Theodora; Hohaus, Thorsten; Gonin, Marc; Kroll, Jesse H.; Worsnop, Doug R.; Goldstein, Allen H.

2011-09-13

446

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

447

Ventilator-driven xenon ventilation studies  

SciTech Connect

A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-07-01

448

Ventilator-driven xenon ventilation studies  

SciTech Connect

A modification of a common commerical Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilator rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-07-01

449

The XENON100 Dark Matter Experiment  

SciTech Connect

The XENON100 experiment is searching for WIMPs, which are particles that may consist dark matter. It is located in the underground laboratory of Gran Sasso (LNGS) in Italy at a depth of {approx}3600 m.w.e.. The experiment description, its performance and the expected background based on Monte Carlo simulations and material screening along with the projected sensitivities of the experiment are presented. In addition, a brief description of the upgrade XENON100 detector is given.

Tziaferi, E. [Physics Institute, University of Zuerich, Winterthurerstr. 190, Zuerich (Switzerland)

2010-06-23

450

Stirring Up an Elastic Fluid: Critical Viscosity of Xenon-2 (CVX-2)  

NASA Technical Reports Server (NTRS)

Whipped cream stays in place even when turned upside down. Yet it readily flows through the nozzle of a spray can to reach the dessert plate. This demonstrates the phenomenon of shear thinning that is important to many industrial and physical processes. Paints, film emulsions, and other complex solutions that are highly viscous under normal conditions but become thin and flow easily under shear forces. A simple fluid, such as water, does not exhibit shear thinning under normal conditions. Very close to the liquid-vapor critical point, where the distinction between liquid and vapor disappears, the fluid becomes more complex and is predicted to display shear thinning. At the critical point, xenon atoms interact over long distances in a classical model of cooperative phenom